National Research Council Canada Research Articles

Annoyance evaluation of impact sounds on lightweight, concrete and cross-laminated timber floors - A comparative study

For people living in multi-unit residential buildings, neighbor noise and especially impact noise from neighbors, such as dropping objects or footsteps, can affect the quality of living of those who hear the noise. In order to support the inclusion of limits for impact noise in a future edition of the National Building Code of Canada, a project at the National Research Council of Canada has focused on the perceived annoyance from different types of impact sounds for various timber floor-ceiling assemblies. The results from listening experiments showed poor correlation between subjective ratings and objective single number metrics for impact noise due to persons walking without shoes. To extend this evaluation to a wider variety of floor-ceiling assembly types and to validate previous results, another listening experiment was conducted at the National Research Council. Annoyance ratings for ball drops, hammer impacts and footsteps on different lightweight, concrete and cross-laminated timber floor-ceiling assemblies were compared.

Evaluating the measurement of the velocity level difference for building constructions which combine Type A and Type B elements

As part of an ongoing research project in the new four-room flanking facility at the National Research Council Canada, the velocity level differences between cross-laminated timber floors/ceilings and lightweight timber framed walls have been measured according to the standard, ISO 10848-1. The apparent sound reduction indices between the pairs of rooms have also been measured according to ISO 10848-1. The measured apparent sound reduction indices are compared to those predicted according to the standard, ISO 12354-1 based on the measured velocity level differences, the resonant transmission losses and the dimensions of the elements of the flanking paths between the room pairs.

On the acceptance limits for short-term level fluctuation of sound calibrators

To ensure noise measurement accuracy, sound calibrators are used to check the sound level meter accuracy before and after any such measurements, as required by most noise regulations. The sound calibrator itself needs to be calibrated routinely and traceable to national standards. The International Standard IEC 60942, Electroacoustics - Sound calibrators, specifies performance requirements for the sound pressure level, short-term level fluctuation, frequency, and distortion and associated test methods. However, the acceptance limits for short-term level fluctuation specified in IEC 60942 is problematic. The short-term level fluctuation acceptance limits specified in Table 2 of IEC 60942 for the level variations inherited by a stable sinusoid at low frequencies are either underestimated or overestimated. In this paper, a detailed theoretical analysis is presented addressing this particular issue. Closed-form solutions are obtained for typical sinusoidal sound signals. Two experimental setups and measurement results for the validation of the theoretical analysis are also presented. One uses a commercial sound level meter and the other uses a precision sound pressure measurement system developed recently at the National Research Council Canada. A revised table for the acceptance limits is then proposed for the future revision of Table 2 of IEC 60942.

Measured and predicted sound transmission through a laboratory concrete floor

The direct sound transmission through a simple, massive, homogeneous building element with and without lining is investigated experimentally and compared with analytical and empirical models from the literature. A 150 mm thick concrete floor and a 100 mm thick floating floor were measured in the floor transmission facility of the National Research Council Canada, i.e. without flanking sound transmission. In addition to the sound reduction index and the normalized impact sound pressure level, loss factors, radiation efficiencies, and mean squared velocities were recorded in the laboratory. The measured data is compared to established models of sound transmission. A focus is placed on the calculation model of ISO 12354-1 (Appendix B), which uses calculated radiation efficiencies and loss factors to predict the sound reduction index of heavy, homogeneous building elements. Some difficulties with the calculation model and the examples in the standard are discussed. In principle, the results in this study show that the calculation model of ISO 12354-1 gives good estimates when the correct input parameters are used. However, deviations between the calculated and the measured loss factors and radiation efficiencies have large effects on the accuracy of the estimates, particularly in the region around the coincidence frequency.

Primary realization of spectral responsivity in the near infrared using a laser-driven light source

Abstract The National Research Council (NRC) Canada has realized the spectral responsivity scale from 900 nm to 1600 nm using a Xe-based laser driven light source, double subtractive monochromator system, and an absolute cryogenic radiometer. An NRC-designed InGaAs sphere transfer standard radiometer was calibrated with combined relative standard uncertainties below 0.135 % (k=1). The scale realization was also performed with a 100 W tungsten lamp, as previously done at NRC. Calibration results and uncertainties in spectral responsivity measurements with each broadband light source are compared and presented.

An Interactive Vision-Based 3D Augmented Reality System for In-Home Physical Rehabilitation: A Qualitative Inquiry to Inform System Development.

Postoperative physical rehabilitation is crucial after total joint replacement (TJR). However, completing the recommended levels of postoperative physical exercise is challenging for many older adults with TJR. Lack of adequate postoperative physical exercise has negative consequences on rehabilitation outcomes. Innovative rehabilitation tools for postoperative physical exercises are needed to ensure successful rehabilitation outcomes among older adults with TJR. The aim of this study is to explore key knowledge users' perspectives about how to design an interactive vision-based three-dimensional augmented reality system (3D ARS) to support in-home postoperative physical rehabilitation for older adults with TJR. We conducted a qualitative descriptive study involving 11 semi-structured interviews and six focus groups with 42 older adults with TJR and four unrelated family caregivers. Data were analysed using thematic analysis. Participant insights were grouped into two main themes: (1) dreaming up possibilities and (2) being pragmatic. The first theme captured participants' reflections on the potential utility of a 3D ARS for postoperative physical rehabilitation and features that could be embedded in the 3D ARS to support successful postoperative physical rehabilitation. The second theme captured participants' reflections on practical issues and considerations that could impact access and usage of the 3D ARS. These findings provide researchers, rehabilitation providers and system developers with the foundations for designing, implementing and evaluating innovative augmented reality tools that support effective in-home physical rehabilitation among older adults with TJR. Research users (i.e., individuals and organisations invested in and using the research findings) were actively engaged throughout this work. Specifically, a meeting was held between the research team and representatives of an Expert by Experience team (individuals with lived experience), which was established to support the National Research Council's (organisation) Aging in Place programme. During this meeting, the idea to develop and evaluate an ARS for postoperative physical rehabilitation of older adults with TJR was supported. Research users had the opportunity to review the current study protocol and provide feedback on the study design, offering direction to maximize the relevance and usefulness of our findings to the National Research Council Canada's Aging in Place programme. Research users contributed to participant recruitment efforts and the development of the interview guide. Two Experts by Experience also agreed to be on the Advisory Panel for this multi-phased study, supporting active engagement and centring the voice of research users in knowledge creation and implementation. These experts reviewed a brief report of the current study findings, and continue to guide how the study findings are used to inform the next phase of this multi-phased research.

Development of a 4-in-1 Device to Measure Component Properties of Gas Diffusion Layer/Porous Transport Layer for Both Proton Exchange Membrane Fuel Cell and Water Electrolyzer

This work aims at developing a 4-in-1 device to simultaneously measure parameters under compression (UC), including thickness (TUC), resistivity (RUC, through-plane), and in-plane permeability (IPP-UC), and to separately measure through-plane permeability (TPP). The simultaneous measurement of TUC/RUC/IPP-UC is accomplished through an annulus sample by measuring the flow rate–pressure relationship in a radial flow [1]. By adding a two-piece adaptor, TPP can also be measured using a disk sample. Typical TUC/RUC/IPP-UC/TPP curves of a gas diffusion layer (GDL) are shown in Figure 1. Upon the design requirements, the TUC/RUC/IPP-UC/TPP tester is calibrated and validated.The 4-in-1 device was originally designed for the characterization of the GDL, a key component of the membrane electrode assembly (MEA) for a proton exchange membrane (PEM) fuel cell. The GDL properties are greatly associated with the cell performance, especially under compression. To ensure the quality of GDLs, it is of great importance to characterize GDL properties with respect to the component standardization and specification. The application of the 4-in-1 device was later extended for the characterization of the porous transport layer (PTL), a crucial component for the anode of PEM water electrolyzer in responding to the increased research and efforts made in the development of, mostly, Ti-based PTLs for PEM water electrolysis [2]-[4] , as commercially available PTLs are basically materials borrowed from other applications, e.g., filtration.The developed TUC/RUC/IPP-UC/TPP device has been proven to be a useful tool for the quality control (QC) of GDLs and PTLs, facilitating the component development, complementing the component supply chain, contributing to cell reliability, and thus reduction of cost, for both the PEM fuel cell and PEM water electrolysis technologies. Acknowledgements This work is financially supported by the Office of Energy Research and Development (OERD) and the Advanced Clean Energy (ACE) Program of the National Research Council Canada (project #NRC-23-140).

Parametric investigation of aerodynamic performance degradation due to icing on a symmetrical airfoil

Ice accretion on lifting surfaces induces an aerodynamic penalty in lift and drag on an aircraft. This performance degradation depends on the geometric features, type, and surface characteristics of the accreted ice on the airfoil. In the present work, we propose a set of two-parameter, low-order models to represent some of the typical ice topologies: glaze, rime, and horn. The parametric space is swept for all types of ice to isolate the aerodynamic changes causing performance degradation on a canonical symmetrical airfoil, which is the representative airfoil used by the National Research Council of Canada's platform for ice accretion and coatings tests with ultrasonic readings platform for in-flight icing tests. The three ice topologies show a self-similar trend between the stall angle of attack and the ice thickness, with the horn-type of ice imparting the greatest drag and lift penalty due to strong boundary layer separation. The relative effect of ice roughness plays a secondary role in performance degradation, and in some cases, the roughness causes a thicker and more resilient boundary layer, which can, under very specific icing conditions, enhance the aerodynamic performance.

Transient Three-Dimensional Measurement of Ice Crystal Accretion Using a Plenoptic Camera

Monitoring the three-dimensional formation of ice layers on airfoils during icing wind tunnel experiments is extremely challenging. For the first time, this paper demonstrates the use of a single plenoptic camera to perform transient, nonintrusive in situ measurements of ice crystal accretion. Experiments have been conducted in the Altitude Icing Wind Tunnel at the National Research Council of Canada under different icing conditions to assess the potential of the new technique. Using the camera in a close-up configuration, the results show the evolution of the three-dimensional shape of the accreted ice in high spatial and temporal resolution and in absolute metric units. The computed surface meshes allow for a detailed analysis in terms of ice shape, surface area, and ice volume. Posttest shapes are compared to measurements taken using a commercial laser scanner. Although not rated for ice surfaces, this device is used as a reference to compare the detailed surface structure after registering the data sets. The results of the two methods are in good agreement and show a mean relative deviation of the plenoptic camera of about 0.15 mm.

Characterization of biotinylated human ACE2 and SARS-CoV-2 Omicron BA.4/5 spike protein reference materials

Accurate diagnostic and serology assays are required for the continued management of the COVID-19 pandemic yet spike protein mutations and intellectual property concerns with antigens and antibodies used in various test kits render comparability assessments difficult. As the use of common, well-characterized reagents can help address this lack of standardization, the National Research Council Canada has produced two protein reference materials (RMs) for use in SARS-CoV-2 serology assays: biotinylated human angiotensin-converting enzyme 2 RM, ACE2-1, and SARS-CoV-2 Omicron BA.4/5 spike protein RM, OMIC-1. Reference values were assigned through a combination of amino acid analysis via isotope dilution liquid chromatography tandem mass spectrometry following acid hydrolysis, and ultraviolet–visible (UV–Vis) spectrophotometry at 280 nm. Vial-to-vial homogeneity was established using UV–Vis measurements, and protein oligomeric status, monitored by size exclusion liquid chromatography (LC-SEC), was used to evaluate transportation, storage, and freeze–thaw stabilities. The molar protein concentration in ACE2-1 was 25.3 ± 1.7 µmol L−1 (k = 2, 95% CI) and consisted almost exclusively (98%) of monomeric ACE2, while OMIC-1 contained 5.4 ± 0.5 µmol L−1 (k = 2) spike protein in a mostly (82%) trimeric form. Glycoprotein molar mass determination by LC-SEC with multi-angle light scattering detection facilitated calculation of corresponding mass concentrations. To confirm protein functionality, the binding of OMIC-1 to immobilized ACE2-1 was investigated with surface plasmon resonance and the resulting dissociation constant, KD ~ 4.4 nM, was consistent with literature values.Graphical

Seismic Performance Assessment of Conventional Construction and Ductile Concrete Moment Frames Using Performance-Based Unified Procedure

A Performance-Based Unified (PBU) procedure has recently been proposed by the National Research Council Canada (NRC) to systematically evaluate seismic design requirements available in the National Building Codes (NBC) of Canada. Conventional Construction reinforced Concrete Moment-resisting Frame (CC-CMF) and Ductile reinforced Concrete Moment-Resisting Frame (D-CMF) systems were used in this paper to first assess the proposed PBU procedure and second determine the adequacy of the basis for seismic design requirements in NBC and see its performance margin against different structural performance levels. Results indicate that the detailed screening in the PBU procedure efficiently reduces the number of Incremental Dynamic Analyses (IDA) by more than 60% for CC-CMF while providing remarkable accuracy. It was also found that the CC-CMF system designed for the Normal importance category can provide an adequate margin against Life Safety (LS) performance level objectives, while the D-CMF system designed for the same importance category passes the Collapse Prevention (CP) performance level criteria.

Investigation of differential diffusion in lean, premixed, hydrogen-enriched swirl flames

Hydrogen combustion is a promising alternative to fossil fuel combustion in an effort to reduce our carbon footprint. However, hydrogen combustion is prone to thermodiffusive instabilities largely dependent on differential diffusion, a phenomenon that can lead to higher probabilities of flashback in industrial burners, given hydrogen’s high reactivity and diffusivity. This paper evaluates low-swirl flames of methane and air enriched with hydrogen to highlight the onset of differential diffusion. Testing was conducted in a fully controllable swirl burner, where bulk velocity Uav = 13 m/s and swirl number S = 0.6 were kept constant for each hydrogen–methane blend to isolate increases in flame surface area from increases in turbulence intensity. Furthermore, each fuel blend of hydrogen and methane is evaluated at the same laminar flame speed of SLo = 0.267 m/s to isolate flame stretch effects on the turbulent burning rate. Combined hydroxyl (OH) PLIF and stereoscopic PIV at the National Research Council of Canada were used to analyze the OH fluorescence in a 2D-3C velocity field for each flame condition. High-speed PIV at McGill University was used to resolve local flame phenomena, such as local flame displacement velocity and flame stretch rate. Using these techniques, it can be observed that the flame displaces axially in response to turbulent flame speed while exhibiting increases in flamefront wrinkling. This increased corrugation due to flame stretch is highlighted in the PDFs of local curvature and κSf and is further evidenced by a shift towards positive curvatures (κ> 0) for increasing H2 volume fraction. This trend suggests that there is a strong correlation with increases in turbulent burning rate and positive curvature as a result of differential diffusion, but it is not necessarily a control mechanism of the most forward propagating points proposed by the theory of leading points.

LOW-CRESTED AND EMERGENT BREAKWATERS WITH ECO-FRIENDLY ARMOUR UNITS

Artificial coastal defense systems (such as concrete armour units) frequently host less diverse aquatic populations than natural environments and feature higher concentrations of invasive species (Dafforn et al., 2009). Therefore, coastal structures need to be designed or refitted to achieve sustainable goals through the application of ecological engineering solutions applied to coastal defence structures and for the ecosystem, marine habitat, and biodiversity improvement. Ecological engineering, which integrates ecosystems with engineering principles to construct coastal structures that benefit both humans and the ecosystem, is growing as a means of reducing the adverse ecological impacts of coastal infrastructure (Mitsch & Jorgensen, 2003). Thus, creating new eco-friendly breakwater design guidelines is critical and will benefit from the multidisciplinary involvement of marine biologists and ecologists. The purpose of this experimental modelling study was to provide data on the hydraulic performance and stability of low-crested and emergent rubble mound breakwaters (RMBW) constructed using ecologically friendly armour units under various wave conditions. The University of Ottawa, the National Research Council of Canada (NRC), and ECOncrete collaborated to develop and conduct the physical testing program. Several breakwater models were tested to evaluate their performance, as the idea of an eco-friendly breakwater is still a new area of research. Thus, this experimental program is essential to promote environmentally-friendly armour units in the design of new coastal structures (such as Baker et al., 2018), as well as ecological retrofitting of existing coastal structures. The physical tests were conducted between June 2023 and August 2023 in the Large Wave Flume of NRC’s Ocean, Coastal, and River Engineering Research Center in Ottawa, Canada. ECOncrete's Coastalock armour units were tested in various configurations at a 1/15 scale using two-dimensional low-crested and emergent RMBW models. The hydraulic performance and failure mechanisms of these environmentally-friendly breakwater models were tested under severe wave conditions.

Large-Scale Experimental Model Of Edge Treatments For Constructed Salt Marshes

Large stretches of Canada’s coastlines are lined with legacy dykes (or levees) to provide protection against coastal flooding and erosion. However, future sea-level rise presents a risk to these structures, which may result in the dykes being under designed when exposed to future water levels and wave conditions. Under certain conditions, these dykes can be augmented with a coastal saltmarsh to create a living dyke, which allows for the existing dyke to be more resilient against sea level rise without the need to retrofit the dyke with a higher crest elevation or larger armour stone. The coastal saltmarsh is able to attenuate storm waves, resulting in lower wave energy at the dyke, while also attracting and retaining sediment to combat coastal erosion. The Living Dyke project in Boundary Bay, Canada is a pilot project being used to test the living dyke concept by placing sediment and planting salt marsh vegetation in the foreshore combined with upgrades to the existing dyke. Kerr Wood Leidal Associates Ltd. prepared a preliminary design which incorporated four different edge treatment features that are to be installed at the offshore edge of a newly constructed salt marsh platform in order to attenuate wave energy and retain the placed sediment before the planted vegetation can be established. The proposed edge treatment features included a natural sand edge, a rounded gravel berm, an oyster-shell filled bag berm, and a brushwood dam. Large scale (full scale for all edge treatment feature tests except for the brushwood dam which was conducted at half-scale) physical model experiments were carried out by the National Research Council of Canada’s Ocean, Coastal and River Engineering Research Centre in their Large Wave-Current Flume to investigate the performance, including stability of the edge treatment features, wave attenuation ability, and stability of the salt marsh platform, of these edge treatment features under varying water level and wave conditions that are present at Boundary Bay.

Numerical Icing Simulations of Cylindrical Geometry and Comparisons to Flight Test Results

There is growing interest in government and industry to use numerical simulations for the Certification by Analysis of aircraft ice protection systems as a cheaper and more sustainable alternative to wind-tunnel and flight testing. The ice accretion on a cylindrical test article mounted under the wing of the National Research Council of Canada’s Convair-580 research aircraft during a flight test in Appendix O icing conditions was simulated using Ansys FENSAP-ICE™. A multishot simulation with input parameters averaged over the full icing period led to an increased level of liquid catch and ice accretion (by mass), and a broader ice profile when compared to a simulation with shot-averaged input parameters. An additional simulation using Ansys’ proprietary “extended icing data with vapor solution” method for calculating heat fluxes at the icing surface resulted in a broader ice profile in comparison to the classical technique, which produced a similar amount of accretion by mass. No combination of simulation settings, input parameters, and multishot methods tested in this study generated the same level of surface detail observed during flight testing, however, the amount of ice accretion, general location of ice features, and formation processes were in good agreement with the experimental results.

Tony F. W. Embleton in the Acoustics Section, Physics Division, of the National Research Council of Canada (NRCC)

Tony completed his PhD in three years at Imperial College (London) studying under Dr. R.W.B. Stephens. He then joined George Thiessen and Edgar Shaw at NRCC to form the core of what became arguably the most influential and productive research group in acoustics in Canada from the 1960s to the 1980s. An important activity was service to industry, a role Tony embraced by collaborating with industry associations, participating in committees and directing his research activities. Working with George Thiessen, he succeeded in reducing the noise of couch rolls, a major source of noise in paper making, by randomizing the pattern of holes through which air was sucked to dry the paper. Other successful noise control projects included staggered stator blades for gas turbine engines and mufflers for rock drills. Tony made seminal contributions to outdoor sound propagation and refined condenser microphone calibration. In addition to his research and outreach, he found time for professional service to the ASA and CAA, including serving as founding editor of what is now Canadian Acoustics, and to develop standards and mentor younger scientists, He is remembered for his cheerfulness and willingness to provide advice and engage in conversation on any and all topics.

Tony Embleton—Distinguished researcher, successful manager, consummate acoustician

Tony F. W. Embleton was a distinguished researcher in acoustics. His early career focused on practical noise control projects and experimental non-linear acoustics. Later, Tony made important contributions to the understanding of sound propagation outdoors. Tony spent much of his career at the National Research Council of Canada (NRCC). His professional homes were the ASA and the CAA. Tony received numerous awards from the ASA for his work, including the R. Bruce Lindsay Award in 1964, the ASA Silver Medal in Noise in 1986, and the ASA Gold Medal in 2002 “For fundamental contributions to understanding outdoor sound propagation and noise control and for leadership in the Society.” Tony recognized the value of professional organizations and served the ASA as Vice-President (1977–78) and President (1980–81). He also understood the importance of practical applications in acoustics serving as ASA Standards Director (1993–97), navigating the organization through a tough period, and growing the program toward a solid future. Most importantly, Tony was known for his kind and generous spirit, and his outreach and inspiration to newer colleagues. Many of us are the grateful beneficiaries of his gentle enthusiasm.

Residential outdoor-to-indoor acoustic conditions: Method and pilot data

Health and well-being of people is directly influenced by the indoor environmental quality of the buildings they occupy. Noise exposure, for example, is not only a cause of annoyance but it is established as a risk factor for the development of cardiovascular diseases and it is a cause of sleep disturbance. As part of a broader research project focused on establishing guidance for suitable interior conditions for adults as they age, the National Research Council of Canada is developing a field study to measure, among other environmental conditions, outdoor-to-indoor noise conditions at homes. Objective parameters such as sound pressure levels will be monitored for a period of time and compared to residents’ health and well-being assessments through sensors and surveys. The methodology and instrumentation used for the acoustic measurements will be presented as well as the early results from pilot tests. The future outcomes of this study will contribute to guidance for both new-build and retrofit scenarios of dwellings for aging in place.

The Impact Guide: Adapting ISO 12354-2 for calculating impact sound transmission to the North American context

To support a potential introduction of an impact sound requirement into one of the next editions of the National Building Code of Canada, the National Research Council of Canada has initiated several research projects. For one of these projects, an industry-sponsored consortium has been formed with the goal of providing supporting documents and online tools to help building designers incorporate impact sound requirements into their work. The main guide document, following the model of research report RR-331 for airborne sound, provides guidance and explanations on how to calculate and combine direct and flanking sound transmission, in this case for impact sound. The guide uses the method given in ISO 12354-2, adapted to the relevant ASTM standards used in North America. This contribution provides an overview of the work to create the impact sound guide document, how the implementation of ISO 12354-2 is achieved using ASTM standards and presents several example calculations highlighting the need to consider flanking sound transmission for impact sound.

Evaluating the perceived annoyance from impact sounds: Validation of previous experiments with an expanded set of recordings

Impact noise from neighbors in multi-unit residential buildings is commonly seen as an annoyance that may reduce the quality of life of building occupants. A project at the National Research Council of Canada has been evaluating the perceived annoyance from different types of impact sound, through the implementation of listening experiments in Canada, Korea, and Germany. A comparison among the countries revealed that test participants agreed on the relative annoyance of different impact sources, but the absolute levels of the annoyance were different between participants from the three countries. To explain the differences between the participants from the three countries, moderating factors, such as the test participants’ housing situation and noise sensitivity, were taken into account. In order to validate the previous findings, the results from a further listening experiment conducted at the National Research Council using the same methodology but with a new set of impact sounds recorded on a wider variety of floor-ceiling assembly types will be presented.