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Thermal-wave resonant cavity signal processing
No full textThe thermal-wave resonant cavity (TWRC) technique has been used for thermal diffusivity measurements by many researchers. This study aims to reduce the uncertainty associated with TWRC signal processing (curve fitting) by means of numerical simulation and experimental verification. Simulations show that the plot of signal amplitude versus cavity length can be fitted to a simplified model reported previously when the initial fitting position is at least twice the thermal-wave diffusion length (2 \u3bcg), and that the uncertainty caused by different end positions is negligible in the range of 6\u201310 \u3bcg. Upon consideration of the simulation results, signal-to-noise ratio, and clearly defined amplitude curve shape, fitting ranges of about 2.2\u20138.0 \u3bcg and 2.2\u20138.7 \u3bcg were chosen for the experimental data. Thermal diffusivity values (1.438 \ub1 0.001)
7 10 127 and (1.436 \ub1 0.001)
7 10 127 m2 s 121, respectively, were obtained for distilled water, in excellent agreement with the accepted literature value. The ratio of standard deviation to the mean value is smaller than 0.07%, one order of magnitude lower than typical results reported in the literature. Similar simulation results were obtained for air and methanol as intra-cavity samples.Peer reviewed: YesNRC publication: Ye
Atlantic Canadian Cyanobacterial Workshop 2018: workshop final report
No full textThe last few summers have seen an unprecedented rise in the occurrence and impact of cyanobacterial blooms in the lakes and rivers of Atlantic Canada. These have already affected recreational waters, harmed pets and will cause ongoing issues as they reoccur in the region over the coming years.
The main goal of the Atlantic Canadian Cyanobacterial Workshop (ACCW) was to bring together the diverse group of stakeholders involved in monitoring, managing or studying cyanobacteria and their toxins in Atlantic Canada so as to build awareness of emerging needs and existing expertise in the region. By increasing awareness of common challenges and existing capabilities a foundation can be developed for ongoing discussion and collaboration that will be needed to effectively manage the issue going forward.Peer reviewed: NoNRC publication: Ye
Design of a broadband polarization splitter based on anisotropy-engineered tilted subwavelength gratings
No full textPolarization management is of paramount importance in integrated optics, particularly for highly birefringent photonic platforms such as silicon-on-insulator. In this work, we present a polarization beam splitter based on a multimode interference coupler incorporating tilted subwavelength gratings. The tilt provides accurate control of the structural anisotropy and enables independent selection of the beat length for two orthogonal polarization states. As a result, device length is reduced to less than 100 \u3bcm while simultaneously achieving broadband operation through subwavelength grating dispersion engineering. Insertion losses below 1 dB and an extinction ratio higher than 20 dB are demonstrated through 3D FDTD simulation in a 131-nm bandwidth.Peer reviewed: YesNRC publication: Ye
A probabilistic high-pressure zone model for local and global loads during ice-structure interactions
No full textFor temperate ice regions, guidance provided by current design codes regarding ice load estimation for thin ice is unclear, particularly for local pressure estimation. This is in part due to the broader issue of having different recommended approaches for estimating local, global, and dynamic ice loads during level ice interactions with a given structure based on region, scenario type, and a variety of other conditions. It is essential from a design perspective that these three scenarios each be evaluated using appropriate definitions for local design areas, global interaction area, and other structural details. However, the need for use of different modeling approaches for ice loads associated with each of these scenarios is not based on ice mechanics but rather has largely evolved as a result of complexities in developing physics-based models of ice failure in combination with the need to achieve safe designs in the face of limited full-scale data and the need for implementation in a probabilistic framework that can be used for risk-based design assessments. During a given interaction, the ice is the same regardless of the design task at hand. In this paper, a new approach is proposed based on a probabilistic framework for modeling loads from individual high-pressure zones acting on local and global areas. The analysis presented herein considers the case of thin, first-year sea ice interacting with a bottom-founded structure based on an empirical high-pressure zone model derived from field measurements. Initial results indicate that this approach is promising for modeling local and global pressures.Peer reviewed: YesNRC publication: Ye
Detection and interpretation of anomalies in building energy use through inverse modeling
No full textThis article presents a study in which three inverse modeling techniques were applied to hourly heating and cooling load data extracted from 35 office buildings in Ottawa, Canada. These modeling techniques were three-parameter change point models, regression trees, and artificial neural networks. The change point models were trained with outdoor temperature data, whereas the other two models were trained with four regressors: outdoor temperature, wind speed, horizontal solar irradiance, and a binary work hours indicator. The correlations among the change point model parameters of individual buildings were analyzed. The sensitivity of heating and cooling load intensities to the four regressors was examined. The models were used to identify several types of energy use anomalies. The anomalies detected by different modeling techniques were generally in agreement. The results indicate that nearly half of the buildings did not have effective after-hours schedules to save energy. In all but three buildings, the cooling change point temperature was lower than the heating change point temperature\u2014indicating a simultaneous heating and cooling problem. Moreover, a few buildings with anomalies potentially related to high air infiltration or overventilation, high thermal conductance, and high solar heat gains during summer were identified.Peer reviewed: YesNRC publication: Ye
An investigation of the influence of close-proximity traffic on the aerodynamic drag experienced by tractor-trailer combinations
No full textRecent research to investigate the aerodynamic-drag reduction associated with truck platooning systems has begun to reveal that surrounding traffic has a measurable impact on the aerodynamic performance of heavy trucks. A 1/15-scale wind-tunnel study was undertaken to measure changes to the aerodynamic drag experienced by heavy trucks in the presence of upstream traffic. The results, which are based on traffic conditions with up to 5 surrounding vehicles in a 2-lane configuration and consisting of 3 vehicle shapes (compact sedans, SUVs, and a medium-duty truck), show drag reductions of 1% to 16% for the heavy truck model, with the largest reductions of the same order as those experienced in a truck-platooning scenario. The data also reveal that the performance of drag-reduction technologies applied to the heavy-truck model (trailer side-skirts and a boat-tail) demonstrate different performance when applied to an isolated vehicle than to conditions with surrounding traffic. The results suggest that vehicle shape optimization strategies may differ if the influence of wake effects from surrounding traffic is included in product development cycles. Additionally, truck-platooning benefits should be taken in the context of typical traffic scenarios for which trucks are already experiencing a background-platooning effect and therefore may not be expected to attain the benefits relative to isolate-vehicle conditions.Peer reviewed: YesNRC publication: Ye
Llama\ua0peripheral B-cell populations producing conventional and heavy chain-only IgG subtypes are phenotypically indistinguishable but immunogenetically distinct
No full textCamelid ungulates produce homodimeric heavy chain-only antibodies (HCAbs) in addition to conventional antibodies consisting of paired heavy and light chains. In the llama, HCAbs are made up by at least two subclasses (long-hinge IgG2b and short-hinge IgG2c HCAbs vs. conventional heterotetrameric IgG1s). Here, we generated murine monoclonal antibodies (mAbs) specific for the hinge-CH2 boundary of llama IgG2b (mAb 1C10) and the Fc of llama IgG2c HCAbs (mAb 5E4). Flow cytometric analysis of llama peripheral blood lymphocytes revealed that IgG1+, IgG2b+ and IgG2c+ B cells could be distinguished using mAbs 1C10/5E4 but had equivalent expression of three other cell-surface markers. MiSeq sequencing of the peripheral B cell repertoires of three llamas showed that (i) IgG2b and IgG2c HCAbs were present in similar proportions in the repertoire, (ii) a subset of IgG2b and IgG2c HCAbs, but not IgG1s, entirely lacked a hinge exon and showed direct VHH-CH2 splicing; these \u201chingeless\u201d HCAbs were clonally expanded, somatically mutated and derived from hinged HCAb precursors, (iii) substantial repertoire overlap existed between IgG subclasses, especially between IgG2b and IgG2c HCAbs, (iv) the complementarity-determining region (CDR)-H3 length distributions of IgG2b and IgG2c HCAbs were broader and biased towards longer lengths compared with IgG1s due to increased N-nucleotide addition, (v) IgG2b and IgG2c HCAbs used a more restricted set of IGHV genes compared with IgG1s, and (vi) IgG2b and IgG2c HCAbs had elevated somatic mutations rates of both CDRs and framework regions (FRs) compared with IgG1s, especially of CDR-H1 and FR3. The distinct molecular features of llama IgG1, IgG2b and IgG2c antibodies imply that these subclasses may have divergent immunological functions and suggest that specific mechanisms operate to diversify HCAb repertoires in the absence of a light chain.Peer reviewed: YesNRC publication: Ye
Mesophilic, thermophilic and hyperthermophilic acidogenic fermentation of food waste in batch: effect of inoculum source
No full textDistinctions in hydrolysis and acidogenesis were examined for a series of anaerobic batch reactors inoculated with three different anaerobic mixed cultures (mesophilic, thermophilic and hyperthermophilic anaerobic sludge) and operated at the temperature of inoculum\u2019s origin and additionally at 70\u202f\ub0C. Hyperthermophilic temperatures led to increased hydrolysis rates during the start-up stage but a rapid drop in pH limited the overall hydrolysis efficiency, indicating the importance of pH control to sustain the high reaction rates at higher temperatures. No significant difference (P\u202f>\u202f0.05) was observed among hydrolysis efficiencies obtained for different reactors which ranged between 27\u202f\ub1\u202f3% and 40\u202f\ub1\u202f14%. The highest fermentation yield of 0.44\u202fg COD of fermentation products/g VSS-CODadded was obtained under thermophilic conditions, followed by mesophilic (0.33\u202fg COD ferm. prod./g VSS-CODadded) and hyperthermophilic conditions (0.05\u20130.08\u202fg COD ferm. prod./g VSS-CODadded). Fermentative performance was better at mesophilic and thermophilic conditions as indicated by improved production of volatile fatty acids (VFA). VFAs accounted for 60\u201371% of the solubilised matter at thermophilic and mesophilic conditions. Acetic acid formed the primary VFA (70%) at mesophilic temperatures, while butyric acid was the major VFA at thermophilic (60%) conditions. Hyperthermophilic conditions led to increased production of lactic acid, which comprised up to 32% of the solubilised matter. Overall, the results indicate that different operating temperatures may not significantly affect the substrate degradation efficiency but clearly influence the biotransformation pathways.Peer reviewed: YesNRC publication: Ye
Parameters affecting the accuracy of nanoparticle shape and size measurement in 3D
No full textWhile electron tomography can be used to visualize objects at nanoscale, it is difficult to perform reproducible quantitative measurements. Here we measure the shape and size of nanoparticles (NPs) in three dimensions (3D) using electron tomography. We evaluated the accuracy of maximum Feret diameter (Feretmax), minimum Feret diameter (Feretmini) and volume of NPs measurements from reconstructed 3D images which were obtained from data acquired with varied electron dose. We perform both simulations and experiment to clarify what factors effect on the accuracy of the NP shape measurement. Based on the results, suitable reconstruction methods and threshold for binarization were evaluated. We also report comparison results obtained on exactly the same samples in two different laboratories.Peer reviewed: YesNRC publication: Ye