Chan J.L.,University of Western Ontario |
Experimental Brain Research | Year: 2013
Everyday life requires the ability to flexibly switch between tasks. Often, task switching is accompanied by concurrent cognitive activities that compete for limited attentional resources. This study aimed to characterize the effects of attentional load on task switching. In experiment 1, participants performed an interleaved pro-saccade and anti-saccade task. In experiment 2, participants performed an interleaved pro-saccade and anti-saccade task simultaneously with a rapid serial visual presentation task that has been shown to create an attentional load. Error rates and reaction times of pro-saccades and anti-saccades were analysed for both experiments separately and together. Overall, error rates and reaction times increased with attentional load. With attentional load, switches to pro-saccades were associated with increased error rates and reaction times, whereas switches to anti-saccades were only associated with increased error rates. We propose that attentional load interferes with neural task-set representation and that the resulting executive control is different for the dominant and non-dominant task. © 2013 Springer-Verlag Berlin Heidelberg.
Pardalopoulos S.I.,University of Nicosia |
Earthquake Engineering and Structural Dynamics | Year: 2017
Historical constructions are part of the world heritage, and their survival is an important priority. Comprising mostly unreinforced, load-bearing masonry, heritage buildings may date anywhere from antiquity to the 19th and early 20th century. Being exposed to the elements over the years, they are in various states of disrepair and material degradation. Based on postearthquake reconnaissance reports, these structures occasionally behave rather poorly, even in moderate seismic events, undergoing catastrophic damage and collapse, whereas retrofitting is governed by international conventions regarding noninvasiveness and reversibility of the intervention. The complexity of their structural systems (continuous structural components, lack of diaphragm action, material brittleness, and variability) challenges the established methods of condition assessment of preretrofitted and postretrofitted heritage constructions. The most advanced state of the art in materials and analysis tools is required, far more complex than with conventional buildings. Thus, an assessment procedure specifically geared to this class of structures is urgently needed, in order to assist engineers in this endeavor. The objective of this paper is the development of a performance-based assessment framework that is palatable to practitioners and quite accurate in seismic assessment of unreinforced masonry buildings with no diaphragm action. The underlying theoretical background of the method is illustrated with reference to first principles: global demand is obtained from the design earthquake scenario for the region, using empirical estimates for the prevailing translational period of the system; deformation demands are localized using an approximation to the translational 3-D shape of lateral response, estimated using a uniform gravitational field in the direction of action of the earthquake; acceptance criteria are specified in terms of relative drift ratios, referring to the in-plane and the out-of-plane action of the masonry piers. The quantitative accuracy of the introduced procedure is evaluated through comparison with detailed time-history dynamic analysis results, using a real life example case study. Qualitative relevance of the results is evaluated through comparison of the location and extent of anticipated damage estimated from the proposed assessment procedure, with reported records of the building damages that occurred during a significant past earthquake event. © 2017 John Wiley & Sons, Ltd.
Lam J.C.W.,Queen's University |
Lam J.C.W.,Lassonde |
Jain P.K.,Queen's University
IEEE Transactions on Power Electronics | Year: 2014
Light emitting diode (LED) lamps with ac-input (50 or 60 Hz) usually require an electrolytic capacitor as the dc-link capacitor in the driver circuit to: 1) balance the energy between the input and output power, and 2) to minimize the low-frequency component of the output ripple across the LEDs. The lifetime of this capacitor, however, is much shorter than that of a LED. To maximize the potential lifetime of the LED lighting system, a new pulsating current driving LED driver that does not require any electrolytic capacitors or complicated control circuits to minimize the low-frequency (i.e., 100 or 120 Hz) output ripple is proposed in this paper. The proposed circuit is simple and a single-switch topology is designed to simplify the controller design. The proposed circuit is able to reduce the energy storage capacitance to a few microfarads range, so that film capacitor can be used to replace the unreliable electrolytic capacitor. The circuit operating principles and its theoretical analysis are provided in this paper. Simulation and experimental results are given on a 9-W LED lamp to highlight the merits of the proposed circuit. © 2014 IEEE.
Waghmare P.R.,University of Alberta |
Gunda N.S.K.,Lassonde |
Scientific Reports | Year: 2014
Recent surge in the development of superhydrophobic/superoleophobic surfaces has been motivated by surfaces like fish scales that have hierarchical structures, which are believed to promote water or oil repellency. In this work, we show that the under-water oil repellency of fish scales is entirely due to the mucus layer formation as part of its defense mechanism, which produces unprecedented contact angle close to 180°.We have identified the distinct chemical signatures that are responsible for such large contact angle, thereby making fish scale behave highly superoleophobic inside the water medium. In absence of the mucus layer, it is found that the contact angle decreases quite dramatically to around 150°, making it less oleophobic, the degree of such oleophobicity can then be contributed to its inherent hierarchical structures. Hence, through this systematic study, for the first time we have conclusively shown the role of the fish's mucus layer to generate superoleophobicity and negate the common notion that hierarchical structure is the only reason for such intrinsic behavior of the fish scales.
Hamidi F.,Lassonde |
Conference on Human Factors in Computing Systems - Proceedings | Year: 2014
Digital media can engage children in therapeutic and learning activities. Incorporating living media in these designs can create feelings of empathy and caring in users. We present, Rafigh, a living media interface designed to motivate children with speech disorders to use their speech to care for a living mushroom colony. The mushrooms' growth is used to communicate how much speech is used during interaction. The main focus of the interface is to motivate children to use their speech as part of interaction.
Reddy S.N.,Lassonde |
Nanda S.,Lassonde |
Dalai A.K.,University of Saskatchewan |
International Journal of Hydrogen Energy | Year: 2014
Hydrogen from waste biomass is considered to be a clean gaseous fuel and efficient for heat and power generation due to its high energy content. Supercritical water gasification is found promising in hydrogen production by avoiding biomass drying and allowing maximum conversion. Waste biomass contains cellulose, hemicellulose and lignin; hence it is essential to understand their degradation mechanisms to engineer hydrogen production in high-pressure systems. Process conditions higher than 374 °C and 22.1 MPa are required for biomass conversion to gases. Reaction temperature, pressure, feed concentration, residence time and catalyst have prominent roles in gasification. This review focuses on the degradation routes of biomass model compounds such as cellulose and lignin at near and supercritical conditions. Some homogenous and heterogeneous catalysts leading to water-gas shift, methanation and other sub-reactions during supercritical water gasification are highlighted. The parametric impacts along with some reactor configurations for maximum hydrogen production and technical challenges encountered during hydrothermal gasification processes are also discussed. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Sensors (Basel, Switzerland) | Year: 2015
Recent advances in integrated biosensors, wireless communication and power harvesting techniques are enticing researchers into spawning a new breed of point-of-care (POC) diagnostic devices that have attracted significant interest from industry. Among these, it is the ones equipped with wireless capabilities that drew our attention in this review paper. Indeed, wireless POC devices offer a great advantage, that of the possibility of exerting continuous monitoring of biologically relevant parameters, metabolites and other bio-molecules, relevant to the management of various morbid diseases such as diabetes, brain cancer, ischemia, and Alzheimer's. In this review paper, we examine three major categories of miniaturized integrated devices, namely; the implantable Wireless Bio-Sensors (WBSs), the wearable WBSs and the handheld WBSs. In practice, despite the aforesaid progress made in developing wireless platforms, early detection of health imbalances remains a grand challenge from both the technological and the medical points of view. This paper addresses such challenges and reports the state-of-the-art in this interdisciplinary field.
Pratt D.Y.,University of Saskatchewan |
Wilson L.D.,University of Saskatchewan |
Journal of Colloid and Interface Science | Year: 2013
Chitosan-glutaraldehyde copolymer sorbents were synthesized by reacting variable weight ratios (low, medium, and high) of glutaraldehyde with fixed amounts of chitosan. Two commercially available chitosan polymers with low (L) and high (H) relative molecular weights were investigated. The chitosan-glutaraldehyde (Chi-Glu) copolymer sorbents are denoted as CPL-X or CPH-X where X denotes the incremental level (X=-1, -2, -3) of glutaraldehyde. The copolymers were characterized using FT-IR spectroscopy and TGA. The solid-solution sorption isotherms in alkaline aqueous solution for the copolymers were characterized using absorbance and emission based spectroscopic methods for p-nitrophenol (PNP) and the arsenate oxoanion HAsO42- species, respectively. The Sips isotherm model was utilized to obtain sorption parameters at pH 8.5 and 295K (i.e. sorbent surface area, sorption capacity and removal efficiency) for each copolymer sorbent. The sorbent surface areas for the low molecular weight chitosan copolymers are listed in parentheses (m2g-1), as follows: CPL-1 (124), CPL-2 (46.7) and CPL-3 (31.6). The high molecular weight chitosan copolymers are as follows: CPH-1 (79.8), CPH-2 (64.7) and CPH-3 (96.3). The removal efficiencies depend on the pH, temperature, and the relative amounts of sorbate and sorbent. The sorbent removal efficiencies for p-nitrophenol ranged between 7.1% and 49%, and the values for H2AsO42- ranged between 31% to 93% for the low and high molecular weight copolymers. © 2012 Elsevier Inc..
Bastani A.,Concordia University at Montréal |
Haghighat F.,Concordia University at Montréal |
Renewable and Sustainable Energy Reviews | Year: 2014
While space conditioning load contributes largely in grid critical peak, shifting a part or full to the off-peak period could have significant economic effects on both energy supply and demand sides. This shifting technique is accomplished by storing energy during off-peak periods to be utilized during peak periods. The wallboard enhanced with PCM can provide latent heat thermal energy storage (TES) distributed in the whole surface area of the building envelope and evade the enhanced thermal mass in light weight buildings. Identifying the best design parameters of the PCM wallboard is the main key to apply this latent heat TES efficiently. The effective dimensionless numbers on the thermal dynamics of a PCM wallboard were identified. Moreover, the impact of the change of those numbers on the time required for the wallboard to become fully charged was evaluated. This parametric study provided a tool to characterize the required thickness of a PCM wallboard which needs to be charged during the off-peak. The tool presents the Fourier number as a correlation of Biot number and Stefan number. Moreover, the impact of melting range on the charging time of a PCM wallboard was investigated. © 2014 Elsevier Ltd.