Ast\ue9rismes et constellations

Peer reviewed: NoNRC publication: Ye

Patterns of the stars

Peer reviewed: NoNRC publication: Ye

An old, far-flung rock

Peer reviewed: NoNRC publication: Ye

Laser-additive repair of cast Ni\u2013Al\u2013bronze components

To emulate the refurbishment of service-damaged cast nickel aluminum bronze (NAB) components, a laser-additive repair process using NAB powder feed was developed. Process parameters were first optimized using Taguchi experimental design based on the lowest dilution ratio criterion. The dilution ratio was obtained from single weld beads deposited on flat substrates. Using the optimum process window developed on the flat substrates, the process parameters were further modified to deposit multiple weld beads in a grooved substrate, which was used to emulate remanufacturing of a service-damaged surface condition. Using the optimum laser-additive repair process developed, sound deposits with no cracks but some micropores at acceptable levels for the application, were successfully manufactured. The microstructure and microindentation hardness of the deposited specimen were evaluated in the as-deposited condition.Peer reviewed: YesNRC publication: N

Elastomers and plastics for resisting erosion attack of abrasive/erosive slurries

Elastomers and plastics are widely used as the materials for handling abrasive/erosive slurries because of their wear resistance, toughness, corrosion resistance and light weight. In this study, slurry jet erosion, Coriolis slurry scouring erosion and large particle slurry erosion are used to characterize the erosion resistance of selected elastomers and plastics, including two natural rubbers, a neoprene rubber, a polyurethane and three types of polyethylene, at different test conditions. The wear rates and wear modes of the tested materials are presented and the relationships between the erosion resistance of these materials and their mechanical properties are discussed. Suitable applications of these materials in slurry transport are also recommended.Peer reviewed: YesNRC publication: Ye

EuroGames16: evaluating change detection in online conversation

We introduce the challenging task of detecting changes from an online conversation. Our goal is to detect significant changes in, for example, sentiment or topic in a stream of messages that are part of an ongoing conversation. Our approach relies on first applying linguistic preprocessing or collecting simple statistics on the messages in the conversation in order to build a time series. Change point detection algorithms are then applied to identify the location of significant changes in the distribution of the underlying time series. We present a collection of sport events on which we can evaluate the performance of our change detection method. Our experiments, using several change point detection algorithms and several types of time series, show that it is possible to detect salient changes in an on-line conversation with relatively high accuracy.Peer reviewed: YesNRC publication: Ye

Application of direct analysis in real time to the study of chemical vapor generation mechanisms: identification of intermediate hydrolysis products of amine-boranes

In order to elucidate controversial results emerging in chemical vapor generation (CVG) for trace element determination, we conducted a series of experiments devoted to the identification of intermediates formed by acid hydrolysis of amine-boranes. For the first time, direct analysis in real time coupled with high-resolution mass spectrometry (DART-Orbitrap) was applied for detection of this class of compounds. Mass spectra of both solid amine-boranes and their aqueous solutions (pH ~\u20098, no hydrolysis) were acquired for understanding their ionization pathway. Mass spectra of aqueous solutions of t-BuNH2\ub7BH3 and Me2NH\ub7BH3 were acquired under conditions that are employed in CVG (0.017\u20134.0 mol L 121 HCl, 0.167\u20130.2 mol L 121 borane reagent). The results disclose a reactivity driven by pH of amine-boranes undergoing hydrolysis. At low acidity, the hydrolysis proceeds according to the currently accepted displacement mechanisms (i.e., R3N\ub7BH3 + H3O+ \u2192 R3NH+ + H2OBH3). At higher acidity, N-tert-butyl, cyclotriborazane, and bis(dimethylamino)boronium were identified, for the first time, during the hydrolysis of t-BuNH2\ub7BH3 and Me2NH\ub7BH3, respectively. Formation of these intermediates was ascribed to a hydrolysis pathway starting with the ionization of the amine-borane, (i.e., R3N\ub7BH3 + H3O+ \u2192 [(H2O)R3NBH2] + + H2). The new evidence explains the anomalous behavior observed in CVG by amine-borane derivatization, and updates the currently accepted mechanisms for the acid hydrolysis of amine-boranes.Peer reviewed: YesNRC publication: Ye

Live long and praise TOR: a role for TOR signaling in every stage of plant life

From scientific advances in medical research to the plethora of anti-aging products available, our obsession with slowing the aging process and increasing lifespan is indisputable. A large research effort has been levied towards this perpetual search for the fountain of youth, yet the molecular mechanisms governing an organism\u2019s lifespan and the causes of aging are only beginning to emerge in animals and remain largely unanswered in plants. One central pathway in eukaryotes controlling cell growth, development and metabolism, the target of rapamycin (TOR), plays an evolutionarily conserved role in aging and the determination of lifespan. The modulation of TOR pathway components in a wide range of species, including the model plant Arabidopsisthaliana have effects on lifespan. However, the mechanisms enabling some of the longest living species to endure, including trees that can live for millennia, have not been defined. Here, we introduce key TOR research from plant systems and discuss its implications in the plant life cycle and the broader field of lifespan research. TOR pathway functions in plant life cycle progression and lifespan determination are discussed, noting key differences from yeast and animal systems and the importance of \u2018omics\u2019 research for the continued progression of TOR signaling research.yesPeer reviewed: YesNRC publication: Ye

Model-based and data-driven anomaly detection for heating and cooling demands in office buildings

A considerable portion of total energy loss within the built environment originates from operational errors during the actual lifespan of a building. With the rise of fully automated commercial buildings, a large amount of sensory data is becoming available that can be leveraged to detect and predict such errors. However, processing these data on-site requires significant knowledge and effort by building operators. In this work, a combination of model-based and data-driven approaches are employed to facilitate the analysis of historical energy demand data. Using change-point models and symbolic quantisation techniques, a large dataset of heating and cooling demand profiles collected from several office buildings are transformed into a format that is easily interpreted by the building operator and is suitable for actionable anomaly detection. Further quantification of anomalies and calculation of potential savings are drawn from the results.Peer reviewed: YesNRC publication: Ye

Nitrogen- and phosphorus-starved Triticum aestivum show distinct belowground microbiome profiles

Many plants have natural partnerships with microbes that can boost their nitrogen (N) and/or phosphorus (P) acquisition. To assess whether wheat may have undiscovered associations of these types, we tested if N/P-starved Triticum aestivum show microbiome profiles that are simultaneously different from those of N/P-amended plants and those of their own bulk soils. The bacterial and fungal communities of root, rhizosphere, and bulk soil samples from the Historical Dryland Plots (Lethbridge, Canada), which hold T. aestivum that is grown both under N/P fertilization and in conditions of extreme N/P-starvation, were taxonomically described and compared (bacterial 16S rRNA genes and fungal Internal Transcribed Spacers\u2014ITS). As the list may include novel N- and/or P-providing wheat partners, we then identified all the operational taxonomic units (OTUs) that were proportionally enriched in one or more of the nutrient starvation- and plant-specific communities. These analyses revealed: a) distinct N-starvation root and rhizosphere bacterial communities that were proportionally enriched, among others, in OTUs belonging to families Enterobacteriaceae, Chitinophagaceae, Comamonadaceae, Caulobacteraceae, Cytophagaceae, Streptomycetaceae, b) distinct N-starvation root fungal communities that were proportionally enriched in OTUs belonging to taxa Lulworthia, Sordariomycetes, Apodus, Conocybe, Ascomycota, Crocicreas, c) a distinct P-starvation rhizosphere bacterial community that was proportionally enriched in an OTU belonging to genus Agrobacterium, and d) a distinct P-starvation root fungal community that was proportionally enriched in OTUs belonging to genera Parastagonospora and Phaeosphaeriopsis. Our study might have exposed wheat-microbe connections that can form the basis of novel complementary yield-boosting tools.Peer reviewed: YesNRC publication: Ye