A Case Study in Estimating Avionics Availability from Field Reliability Data

Under incentivized contractual mechanisms such as availability‐based contracts, the support service provider and its customer must share a common understanding of equipment reliability baselines. Emphasis is typically placed on the information technology‐related solutions for capturing, processing and sharing vast amounts of data. In the case of repairable fielded items, scant attention is paid to the pitfalls within the modelling assumptions that are often endorsed uncritically and seldom made explicit during field reliability data analysis. This paper presents a case study in which good practices in reliability data analysis are identified and applied to real‐world data with the aim of supporting the effective execution of a defence avionics availability‐based contract. The work provides practical guidance on how to make a reasoned choice between available models and methods based on the intelligent exploration of the data available in practical industrial applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Plasma-CVD-coated glass beads as photocatalyst for water decontamination

Amorphous TiO₂ films were deposited on glass microbeads using a specially designed circulating fluidized bed plasma-CVD reactor. The film thickness was varied between 7 and 120 nm. While only little carbon impurity was found, XPS analysis revealed the presence of silicon, sodium and alkaline earth elements in the titania coating. Reduced amounts of these substrate-originating impurities were observed in the thicker films. By ToF-SIMS imaging, cross-sectional TEM and time-resolved dissolution, the titania coatings were proven to be uniform, both per particle and in terms of the film thickness distribution.

The photocatalytic performance of the composite particles was evaluated in a fully irradiated fluidized-bed photoreactor. The thinnest films had some photocatalytic activity in the as-deposited state, possibly induced by the high specific power of the microwave plasma or silicon doping. The thicker films needed a post-deposition calcination at 723 K to achieve catalytic activity. Both the degree of anatase crystallization and the activity were improved by applying thicker films and after UV irradiation-plus-calcining. All films showed good adhesion and abrasion resistance during the photocatalytic tests. The best plasma-CVD films were about 70% as efficient (per unit reactor volume) as the reference material, P-25 immobilized on quartz sand.     

Robust determination of optical path difference: fringe tracking at the infrared optical telescope array interferometer

We describe the fringe-packet tracking system used to equalize the optical path lengths at the Infrared Optical Telescope Array interferometer. The measurement of closure phases requires obtaining fringes on three baselines simultaneously. This is accomplished by use of an algorithm based on double Fourier interferometry for obtaining the wavelength-dependent phase of the fringes and a group-delay tracking algorithm for determining the position of the fringe packet. A comparison of data acquired with and without the fringe-packet tracker shows a factor of approximately 3 reduction of the error in the closure-phase measurement. The fringe-packet tracker has been able so far to track fringes with signal-to-noise ratios as low as 1.8 for stars as faint as mH = 7.0.     

Measuring and predicting environmental concentrations of pesticides in air after application to paddy water systems

In this study, the volatilization of five pesticides applied to an artificial flooded paddy field was assessed using the theoretical profile shape (TPS) and the integrate horizontal flux (IHF) techniques. The dataset derived was utilized to improve the volatilization routine of the rice water quality (RICEWQ) model. The masses of pesticides ethoprophos, procymidone, metalaxyl, chlorpyrifos, and chlorpyrifos methyl volatilized from paddy water and their concentrations in paddy water were determined for a period of 6 d after application. The highest and lowest volatilization losses were observed for chlorpyrifos and metalaxyl, respectively, accounting for 3.3% and 0.03% of their initially applied amount. A rapid pesticide dissipation was evident in paddy water during the study period. The RICEWQ model was used to simulate the fate of pesticides in the artificial paddy system. The Kvolat, an empiric coefficient used by the model as an input parameter, was calculated for all pesticides through model calibration. RICEWQ simulated well the fate of pesticides in paddy water. A significant regression correlation between Henry's law constant (Hk) and Kvolat of the studied compounds was established which could facilitate the parametrization of the model for describing pesticide volatilization.     

Mass spectrometric analysis of illicit drugs in wastewater and surface water

Residues of illicit drugs have been recently found in urban wastewater and surface water. Their levels reflect the amount of drugs collectively excreted by consumers and can therefore be used to estimate drug abuse. An overview of the most widely used illicit drugs and of the analytical methods used for their detection in wastewater and surface water is presented here. Solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry are the techniques that have been used for these investigations. Instrumental conditions and fragmentation patterns of illicit drugs and their metabolites are described.     

PIGA (N,N-Di-n-butyl-5-chloro-2-(4-chlorophenyl)indol-3-ylglyoxylamide), a new mitochondrial benzodiazepine-receptor ligand, induces apoptosis in C6 glioma cells

Mitochondrial benzodiazepine-receptor (mBzR) ligands constitute a heterogeneous class of compounds that show a pleiotropic spectrum of effects within the cells, including the modulation of apoptosis. In this paper, a novel synthetic 2-phenylindol-3-ylglyoxylamide derivative, N,N-di-n-butyl-5-chloro-2-(4-chlorophenyl)indol-3-ylglyoxylamide (PIGA), which shows high affinity and selectivity for the mBzR, is demonstrated to induce apoptosis in rat C6 glioma cells. PIGA was able to dissipate mitochondrial transmembrane potential (DeltaPsim) and to cause a significant cytosolic accumulation of cytochrome c. Moreover, typical features of apoptotic cell death, such as caspase-3 activation and DNA fragmentation, were also detected in PIGA-treated cells. Our data expand the knowledge on mBzR ligand-mediated apoptosis and suggest PIGA as a novel proapoptotic compound with therapeutic potential against glial tumours, in which apoptosis resistance has been reported to be involved in carcinogenesis.     

Immunohistochemical and immunochemical characterization of the distribution of leptin-like proteins in the gastroenteric tract of two teleosts (Dicentrarchus labrax and Carassius auratus L.) with different feeding habits

Leptin is a modulator of food intake and energy homeostasis both in mammals and in some species of nonmammals vertebrates. In this study, we reported for the first time, using an immunohistochemical and immunochemical approach, the presence and distribution of immunoreactivity to leptin-like protein in the gastroenteric tract of Dicentrarchus labrax (bass) and Carassius auratus (goldfish), two teleostean species with different feeding and different adaptative morphological organization of the gastroenteric tract. Bass stomach showed intense immunoreactivity to leptin-like protein in all regions, with immunoreactive cells located at the base of the mucosal plicae and at the apical margin of the gastric crypts. Immunoreactive fibers and neuronal cells were observed close to vascular structures in the pyloric region. In bass and goldfish intestine, rare immunoreactive cells were observed along the mucosal epithelium mostly at the base or the apex of intestinal folds in the proximal and medium intestine; numerous immunoreactive nerve fibers in the circular and longitudinal layers of the tunica muscolaris as well as in the myenteric plexus were observed. Western blot analysis recognized a ～15 kDa signal with a similar expression pattern for goldfish and sea bass. Our results could contribute to confirm the evolutive conservation of leptin-like proteins and their probably precocious functional diversification in fish.     

Sky Region Obstacle Detection and Tracking for Vision-Based UAS Sense and Avoid

A customized detection and tracking algorithm for vision-based non cooperative UAS sense and avoid aimed at obstacles approaching from above the horizon is presented in this paper. The proposed approach comprises two main steps. Specifically, the first processing step is relevant to obstacle detection and tentative tracking for track confirmation and is based on top-hat and bottom-hat morphological filtering, local image analysis for a limited set of regions of interest, and multi-frame processing in stabilized coordinates. Once firm tracking is achieved, template matching and state estimation based on Kalman filtering are used to track the intruder aircraft and estimate its angular position and velocity. An extensive experimental analysis is presented which is based on a large set of flight data gathered in realistic near collision scenarios, in different operating conditions in terms of weather and illumination, and adopting different navigation units onboard the ownship. In particular, the focus is set on flight segments at a range between 3 km and 1.3 km, since the major interest is in understanding algorithm potential for relatively large time to collision. System performance is evaluated in terms of declaration range, probability of correct declaration, average number of false positives, tracking accuracy (angles and angular rates in a stabilized North-East-Down reference frame) and robustness with respect to track loss phenomena. Promising results are achieved regarding the trade-off between declaration range and false alarm probability, while the onboard navigation unit is found to heavily impact tracking accuracy.     

Diarylheterocycle core ring features effect in selective COX-1 inhibition

The COX-1 isoenzyme plays a significant role in a variety of diseases, as it catalyzes the bioprocesses behind many health problems. Among the diarylheterocycle class of COX inhibitors, the isoxazole ring has been widely used as a central heterocycle for the preparation of potent and selective COX-1 inhibitors such as P6 [3-(5-chlorofuran-2-yl)-5-methyl-4-phenylisoxazole]. The role of the isoxazole nucleus in COX-1 inhibitor selectivity has been clarified by preparing a set of new diarylheterocycles with various heterocycle cores. Replacement of isoxazole with isothiazole or pyrazole gave a drastic decrease in COX-1 inhibitory activity, whereas the introduction of an electron-donating group (EDG) on the N-aryl pyrazole allowed recovery of COX-1 inhibitory activity and selectivity. The EDG-equipped 5-(furan-2-yl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (17) selectively inhibits COX-1 activity (IC(50) =3.4 μM; 28% COX-2 inhibition at 50 μM), in contrast to its inactive analogue, 3-(furan-2-yl)-1-phenyl-5-(trifluoromethyl)-1H-pyrazole, which does not bear the methoxy EDG. Molecular docking studies of compound 17 into the binding site of COX-1 shed light on its binding mode.     

Bayesian Estimation of Thermal Conductivity and Temperature Profile in a Homogeneous Mass

International standards propose several methods for measuring thermal conductivity; however, they often require expensive experimental layouts and marginally consider the uncertainty in the estimation procedure. In this article, we propose a temperature transient method and a Bayesian procedure to estimate the thermal conductivity of a homogeneous mass, and to reproduce the entire temperature profile evolution over time by means of latent temperature data. To validate the approach, experiments are conducted giving heating and cooling cycles to a polymethyl methacrylate (PMMA) specimen. Results show the applicability of the proposed approach and good estimations.