57949 research outputs found
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Galvanic corrosion risk assessment of bolt materials in contact with ASTM A1010 steel bridges
No full textThis study has evaluated the galvanic coupling corrosion risk between connection bolt materials with ASTM A1010 structural steel, which has recently emerged for the construction of more corrosion-resistant bridges than weathering steel bridges. Use of A1010 steels containing 10.5% Cr is intended to extend the service life of steel bridges without frequent maintenance requirements caused by corrosion, particularly in regions under severe chloride exposures such as due to heavy use of de-icing salts and in marine environments. The greater corrosion resistance of A1010 steel with a more positive corrosion potential does, however, impose a risk of galvanic corrosion with the connection bolts in direct electrical contact. Here, the galvanic corrosion between A1010 steel and galvanized ASTM A325 Type I bolt was compared to that between weathering steel and galvanized ASTM A325 Type I bolt, as well as that between A1010 steel and ASTM A320 B8 class 2 and A193 B6 stainless steel bolts. A comprehensive experimental investigation measured galvanic coupling current and potential for samples in cells of aerated salt solution, and the galvanic corrosion risk ranking was validated by visual examinations of bolted steel plates exposed to a salt spray testing chamber. The galvanic corrosion risk of using B8 class 2 bolts with A1010 steel was found to be much lower than using galvanized A325 bolts, but B6 bolt material itself experienced severe crevice and pitting corrosion in both simulated salt solution and salt spray testing.Peer reviewed: YesNRC publication: Ye
MeioCapture: an efficient method for staging and isolation of meiocytes in the prophase I sub-stages of meiosis in wheat
No full textBackground: Molecular analysis of meiosis has been hindered by difficulties in isolating high purity subpopulations of sporogenous cells representing the succeeding stages of meiosis. Isolation of purified male meiocytes from defined meiotic stages is crucial in discovering meiosis specific genes and associated regulatory networks. Results: We describe an optimized method termed MeioCapture for simultaneous isolation of uncontaminated male meiocytes from wheat (Triticum spp.), specifically from the pre-meiotic G2 and the five sub-stages of meiotic prophase I. The MeioCapture protocol builds on the traditional anther squash technique and the capillary collection method, and involves extrusion of intact sporogenous archesporial columns (SACs) containing meiocytes. This improved method exploits the natural meiotic synchrony between anthers of the same floret, the correlation between the length of anthers and meiotic stage, and the occurrence of meiocytes in intact SACs largely free of somatic cells. The main advantage of MeioCapture, compared to previous methods, is that it allows simultaneous collection of meiocytes from different sub-stages of prophase I at a very high level of purity, through correlation of stages with anther sizes. A detailed description is provided for all steps, including the collection of tissue, isolation and size sorting of anthers, extrusion of intact SACs, and staging of meiocytes. Precautions for individual steps throughout the procedure are also provided to facilitate efficient isolation of pure meiocytes. The proof-of-concept was successfully established in wheat, and a light microscopic atlas of meiosis, encompassing all stages from pre-meiosis to telophase II, was developed. Conclusion: The MeioCapture method provides an essential technique to study the molecular basis of chromosome pairing and exchange of genetic information in wheat, leading to strategies for manipulating meiotic recombination frequencies. The method also provides a foundation for similar studies in other crop species.Erratum published in volume 19, article 178, May 2, 2019. DOI: 10.1186/s12870-019-1780-4Peer reviewed: YesNRC publication: Ye
Influence of the Femtosecond Laser Induced Loss on the Type II Phase-Shifted FBG Passband
No full textDuring the inscription of Type II Bragg gratings a certain amount of optical loss is induced in the fiber. For Type II phase-shifted gratings, this broadband loss imposes strong restrictions on the grating passband.Peer reviewed: YesNRC publication: Ye
Machine learning-based sensor data modeling methods for power transformer PHM
No full textAn emerging prognostic and health management (PHM) technology has recently attracted a great deal of attention from academies, industries, and governments. The need for higher equipment availability and lower maintenance cost is driving the development and integration of prognostic and health management systems. PHM models depend on the smart sensors and data generated from sensors. This paper proposed a machine learning-based methods for developing PHM models from sensor data to perform fault diagnostic for transformer systems in a smart grid. In particular, we apply the Cuckoo Search (CS) algorithm to optimize the Back-propagation (BP) neural network in order to build high performance fault diagnostics models. The models were developed using sensor data called dissolved gas data in oil of the power transformer. We validated the models using real sensor data collected from power transformers in China. The results demonstrate that the developed meta heuristic algorithm for optimizing the parameters of the neural network is effective and useful; and machine learning-based models significantly improved the performance and accuracy of fault diagnosis/detection for power transformer PHM.Peer reviewed: YesNRC publication: Ye
Monitor and control for the SKA1 CSP Mid.CBF utilizing the Stratix-10 FPGA equipped with HPS
No full textWe present design considerations and a prototyping progress report for a low-level monitor and control communication system designed to operate on the Stratix-10 System on a Chip (SoC) Field Programmable Gate Array (FPGA) equipped with a Hard Processor System (HPS). The goal of this activity is to allow remote clients to use high level communication protocols (ie. TANGO) to access IP blocks within a Stratix-10 FPGA chip by taking advantage of very low latency communication between HPS and the FPGA fabric, eliminating the need to implement Ethernet protocols within the FPGA logic.Peer reviewed: YesNRC publication: Ye
Multisite multivariate disaggregation of climate parameters using multiplicative random cascades
No full textThe Multiplicative Random Cascade (MRC) disaggregation model has been extensively used to disaggregate precipitation in many regions across the globe. In this study, it is adapted to disaggregate a range of climate variables (CV) relevant for hygrothermal modelling of building envelopes. This generalized MRC-G model is further improved by explicitly modelling the cross-correlation structure between CVs in the MRC-G-CV model. A thorough evaluation of MRC, MRC-G, and MRC-G-CV models is performed for five Canadian cities: Ottawa, Vancouver, Calgary, St. Johns, and Winnipeg. Results indicate that the MRC model is able to simulate grid-level statistics with >90% accuracy. Grid-level extreme magnitudes and spatial cross-correlation structures are also well simulated. Error magnitudes associated with hourly predictions indicate superior performance of the models in respect to thermal variables, followed by wind variables, and then moisture related variables. Finally, the performance of MRC-G model towards modelling cross-correlation among CVs is found to improve by >50% in terms of energy distance by explicitly modelling these relationships in the MRC-G-CV model. Results indicate that the MRC model variants demonstrated in this study have the potential to facilitate effective hygrothermal performance evaluation of building envelopes at locations where observational sub-daily climate records are unavailable.Peer reviewed: YesNRC publication: Ye
Neutralization of Clostridium difficile toxin B with VHH-Fc fusions targeting the delivery and CROPs domains
No full textAn increasing number of antibody-based therapies are being considered for controlling bacterial infections, including Clostridium difficile by targeting toxins A and B. In an effort to develop novel C. difficile immunotherapeutics, we previously isolated several single-domain antibodies (VHHs) capable of toxin A neutralization through recognition of the extreme C-terminal combined repetitive oligopeptides (CROPs) domain, but failed at identifying neutralizing VHHs that bound a similar region on toxin B. Here we report the isolation of a panel of 29 VHHs targeting at least seven unique epitopes on a toxin B immunogen composed of a portion of the central delivery domain and the entire CROPs domain. Despite monovalent affinities as high as KD = 70 pM, none of the VHHs tested were capable of toxin B neutralization; however, modest toxin B inhibition was observed with VHH-VHH dimers and to a much greater extent with VHH-Fc fusions, reaching the neutralizing potency of the recently approved anti-toxin B monoclonal antibody bezlotoxumab in in vitro assays. Epitope binning revealed that several VHH-Fcs bound toxin B at sites distinct from the region recognized by bezlotoxumab, while other VHH-Fcs partially competed with bezlotoxumab for toxin binding. Therefore, the VHHs described here are effective at toxin B neutralization when formatted as bivalent VHH-Fc fusions by targeting toxin B at regions both similar and distinct from the bezlotoxumab binding site.Peer reviewed: YesNRC publication: Ye
Source substitution method for obtaining the power transmission from vibrating sources in buildings
No full textThis paper describes a method analogous to the airborne sound source substitution method, to estimate the vibrational power injected by a structure-borne sound source into the supporting building element. The injected vibrational power is required for prediction of the structure-borne sound pressure from vibrating equipment in buildings. The paper focuses on high-mobility sources connected to low-mobility receivers, a situation which is commonly encountered in heavyweight construction. The mobility mismatch simplifies the transformation of laboratory measurement data to prediction of transmitted power in-situ. Three case studies were performed. In the first study, the power injected by a simple test source into a resiliently supported aluminium plate was determined using direct and indirect methods. Source substitution was investigated with different calibration options: steady-state excitation, transient excitation, and spatial averaging. The source power could be determined within 4\u202fdB, compared with direct measurements of the injected power. In the second study, the power injected by a second source into a concrete transmission suite floor was determined. The third study was of a combined heating and power unit on a masonry wall. In this study, a reference sound pressure level in a receiver room was calculated and compared with a criterion curve for the assessment of low-frequency noise complaints. The case studies demonstrate that structure-borne sound source substitution is a promising development of the reception plate method. While the latter can be used if a free reception plate is available, the former circumvents problems of determining the transmitted power into coupled plates and therefore has application to real building conditions. The use of the instrumented hammer for the calibration and the use of spatial averaging significantly simplify the method.Peer reviewed: YesNRC publication: Ye
SPIRou @CFHT: integration and performance of the cryogenic near infra-red spectrograph unit
No full textSPIRou is an innovative near infra-red echelle spectropolarimeter and a high-precision velocimeter for the 3.6 m Canada-France-Hawaii Telescope (CFHT \u2013 Mauna Kea, Hawaii). This new generation instrument aims at detecting planetary worlds and Earth-like planets of nearby red dwarfs, in habitable zone, and studying the role of the stellar magnetic field during the process of low-mass stars / planets formation. The cryogenic spectrograph unit, cooled down at 80 K, is a fiber fed double-pass cross dispersed echelle spectrograph which works in the 0.98-2.40 \u3bcm wavelength range, allowing the coverage of the YJHK bands in a single exposure. Among the key parameters, a long-term thermal stability better than 2 mK, a relative radial velocity better than 1 m.s -1 and a spectral resolution of 70K are required. After ~ 1 year of assembly, integration and tests at IRAP/OMP (Toulouse, France) during 2016/2017, SPIRou was then shipped to Hawaii and completely re-integrated at CFHT during February 2018. A full instrument first light was performed on 24th of April 2018. The technical commissioning / science validation phase is in progress until June 2018, before opening to the science community. In this paper, we describe the work performed on integration and test of the opto-mechanical assemblies composing the spectrograph unit, firstly in-lab, in Toulouse and then on site, at CFHT. A review of the performances obtained in-lab (in 2017) and during the first on-sky results (in 2018) is also presented.Peer reviewed: YesNRC publication: Ye
Suppression of dry-band arcing erosion by silica filler in silicone rubber composites
No full textThe following topics are dealt with: electric breakdown; permittivity; filled polymers; partial discharges; space charge; transformer oil; ageing; power cable insulation; nanocomposites; power transformer insulation.Peer reviewed: YesNRC publication: Ye