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Polarization and wavelength agnostic nanophotonic beam splitter
No full textHigh-performance optical beam splitters are of fundamental importance for the development of advanced silicon photonics integrated circuits. However, due to the high refractive index contrast of the silicon-on-insulator platform, state of the art Si splitters are hampered by trade-offs in bandwidth, polarization dependence and sensitivity to fabrication errors. Here, we present a new strategy that exploits modal engineering in slotted waveguides to overcome these limitations, enabling ultra-wideband polarization-insensitive optical power splitters, with relaxed fabrication tolerances. The proposed splitter relies on a single-mode slot waveguide which is transformed into two strip waveguides by a symmetric taper, yielding equal power splitting. Based on this concept, we experimentally demonstrate -3\ub1 0.5 dB polarization-independent transmission in an unprecedented 390 nm bandwidth (1260 - 1650 nm), even in the presence of waveguide width deviations as large as \ub1 25 nm.Peer reviewed: NoNRC publication: Ye
Determination of aluminium phosphide (AlP) in fumigants by ICP OES
No full textA method for determination of aluminium phosphide (AlP) in fumigants by inductively coupled plasma optical emission spectrometry (ICP OES) is presented. An 8 hour hydrolysis in water achieved complete decomposition of AlP with the released PH3 being absorbed in a medium of KMnO4/H2SO4. The solution was treated with NH2OH.HCl to reduce the excess MnO4- and the PO4-3 so formed was quantitated as P by ICP OES based on external calibration using the P(I) 213.618 nm emission line. A detection limit (3s, n=10) of 0.26 g/100 g AlP and LOQ (10s, n=10) of 0.85 g/100g AlP were realized. Ten commercial samples of fumigants were analysed, providing results in agreement with specifications of ~ 55-60 g/100g and concordant with values generated by the spectrophotometric method, as evidenced by a paired t-test (95% confidence limit).This simple procedure has been adopted by the Institute of Technology of Paran\ue1 - TECPAR (Curitiba, Brazil).Peer reviewed: YesNRC publication: Ye
Expected observing efficiency of the Maunakea Spectroscopic Explorer (MSE)
No full textThe Maunakea Spectroscopic Explorer (MSE) will obtain millions of spectra each year in the optical to near-infrared, at low (R 43 3; 000) to high (R 43 40; 000) spectral resolution by observing <4,000 spectra per pointing via a highly multiplexed fiber-fed system. Key science programs for MSE include black hole reverberation mapping, stellar population analysis of faint galaxies at high redshift, and sub-km/s velocity accuracy for stellar astrophysics. One key metric of the success of MSE will be its survey speed, i.e. how many spectra of good signal-to-noise ratio will MSE be able to obtain every night and every year. This is defined at the higher level by the observing efficiency of the observatory and should be at least 80%, as indicated in the Science Requirements. In this paper we present the observing efficiency budget developed for MSE based on historical data at the Canada-France-Hawaii Telescope and other Maunakea Observatories. We describe the typical sequence of events at night to help us compute the observing efficiency and how we envision to optimize it to meet the science requirements.Peer reviewed: YesNRC publication: Ye
A preliminary study on text mining operator logbooks to develop a fault-frequency model
No full textTextual data in operator logbooks represent an untapped opportunity to retrieve information about the maintenance routines of HVAC equipment and control infrastructure. This paper presents a case study in which seven years' worth of work order logs from 44 buildings on a university campus were analyzed. After extracting HVAC-related terms such as fan, AHU, VAV, stuck, and leak from custom operator descriptions, the apriori algorithm was used to derive association rules that define the coexistence tendencies of the terms in a work order (e.g., coexistence of the terms radiator and leak). Based on this analysis, a preliminary HVAC work order frequency model was put forward. The results indicate that the annual work order intensity per 1000 m2 (10,764 ft2) was about 4. More than 70% of the HVAC-related work orders were issued to address zone-level problems. Among the AHU-level work orders issued for a physical subcomponent, more than 90% were related to fans. Future work is planned to analyze the HVAC-related work order patterns with numeric data from automation and controls networks.Peer reviewed: YesNRC publication: Ye
Numerical modelling of complex parison and sheet formation in blow molding processes using BlowView Software
No full textBlowView is an engineering 2.5D finite element simulation software, developed at NRC, dedicated to simulate conventional extrusion blow molding, twin-sheet extrusion blow molding, stretch blow molding and thermoforming processes. This versatile blow molding simulation software is highly automated, flexible and user-friendly, yet allows users in-depth analysis capabilities for a wide range of materials, including optimization and permeability. Extrusion blow molding, and twin-sheet extrusion blow molding, are extensively used in manufacturing automotive plastic fuel tanks (PFT). These processes consist of three main phases: parison/sheet formation, inflation and part cooling and solidification. The parison/sheet formation is the most critical stage, as the final dimensions and mechanical performance of the PFT is directly related to the initial extrudate shape, which often requires the use of advanced die shaping technologies such as: Vertical Wall Distribution System (VWDS), Partial Wall Distribution System (PWDS), Die Slide Motion (DSM), and/or a combination of all three. These technologies are all available in the BlowView software, and can be handled simultaniously and synchronized with the machine programming points. In order to predict the extrusion with sag and swell, BlowView uses a hybrid approach that couples fluid mechanics to represent the die flow, with solid mechanics to represent the parison/sheet behavior outside the die, and a phenomenological swell model to capture the die geometry effect. This approach permits avoiding instability issues encountered by traditional fluid mechanics, especially at high Weissenberg numbers. After extrusion, the parison/sheet inflation is predicted tacking into account all mold components and their respective position and displacements. The modelling capabilities of NRC\u2019s BlowView software will be presented based on using an industrial case study of a PFT. Permeability and optimization results will be also illustrated.Peer reviewed: YesNRC publication: Ye
Demand control of baseboard heaters: lessons learned from 50-home pilot study
No full textThis paper presents results from a pilot study in 50 occupied homes in Fredericton, New Brunswick, Canada to evaluate a demand response (DR) strategy applied to residential electric baseboard heating loads. The underlying principle is based on storing electricity as thermal energy in the building envelope and household contents before the grid peak demand period, and then discharging that stored energy to maintain conditions for thermal comfort during the peak period. During January and February 2016, a total of 13 DR interventions were executed. This field test showed that a load shift up to a maximum of 3.4 kW, with an average of 1.4 kW, per household was possible for the first hour, depending on the outdoor temperature. We observed a large variation in load shift between homes, partly depending on the thermostat set-point profiles, building and occupant characteristics. The approach holds significant potential for shifting peak loads in locations where electricity is a major source of energy for space heating.Peer reviewed: YesNRC publication: Ye
Development of a phenomenological equation to predict tool wear in friction stir welding by steel grades in Al/Steel lap joining
No full textSince its introduction in the industry, the amount of structures being joined by friction stir welding (FSW) are in progression. Even if low-melting point materials such as aluminium or magnesium represents the highest number of applications, this method can also successfully join materials with different melting point as in the case of aluminium to steel. As lightweigthing structures gained ground in the last few years and will still continue to grow, joining processes combining aluminium to steel effectively need to be developed further. When it comes down to join aluminium to steel, the most common configuration is lap joint which the FSW pin enters into the bottom sheet substrate, thus the steel material. In order to have a FSW tool that lasts a sufficient amount of time, the material needs to sustain high stresses and temperatures and still be affordable, such as WC-based tools. The wear rate of the tool used during the process needs to be known and understood as it dictates the applicability of the FSW method depending of the application. As an example, the sub-frame assembly of the Honda Accord 2013 is joined using aluminium to steel FSW lap joining. Be able to predict when the tool reaches a point where it is no longer effective to produce a sound weld can certainly help to evaluate tool life. Actually, a few papers have produced a series of equations or processes that can predict material losses but they are constraints at the application designed for and will be presented further. This study will assess FSW tool life prediction upon different material configurations, mainly steel grades as it impacts greatly the wear behavior of the tool.Peer reviewed: YesNRC publication: Ye
Effect of hardening heat treatment on the mechanical properties of a 17-4PH stainless steel foam
No full textThis paper presents the results of a study on the impact of a precipitation hardening treatment on the mechanical properties of 17-4PH stainless steel open-cell foams produced using a powder-metallurgy-based process patented by the National Research Council Canada (NRC). Pre-alloyed powder was used to manufacture stainless steel (SS) foams with either medium or high porosity by changing the nature of the organic binder used to process the porous materials. Some of these were kept in the as-sintered state, while others were submitted to the H900 precipitation hardening treatment frequently prescribed for 17-4PH stainless steels. Metallurgical and physical characterization was carried out on the resulting materials, along with mechanical testing at the micro (indentation testing) and macro (compressive testing) scales. It was found that the Medium-Porosity Foams (MPF) and High-Porosity Foams (HPF) had very different morphologies, the HPFs having a delicate porous structure featuring thin sintered walls with many openings (a.k.a. windows) between the main cells, while the MPFs exhibited much thicker walls with few windows connecting the larger pores. As expected from these foam morphologies, the mechanical properties of MPFs were much higher than those of the more porous and delicate HPF materials. For both foam types, the average mechanical properties were improved by the H900 treatment. A comparison with compressive properties of 17-4PH foams taken from the literature resulted in reasonable agreement. However, the large scatter observed on the average compressive properties of the NRC foams and the slightly different structure/composition of the literature materials mean that any comparison between these porous alloys must be interpreted with caution.Peer reviewed: YesNRC publication: Ye