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.
Tao Y.,ETH Zurich |
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2015
This paper presents a 10-bit single-ended SAR ADC suitable for multi-channel neural recording. The proposed ADC introduces several power saving techniques to boost the energy efficiency. The ADC is built with on-chip common-mode buffer for input tracking, which is reused as the pre-amplifier of a current-mode comparator during conversion. A small capacitor is inserted between the amplifier and the capacitive DAC array in order to reduce the capacitive load on the amplifier. A split capacitor array with dual thermometer decoders is proposed to reduce the switching energy. Implemented in 0.13-μm CMOS technology, the ADC achieved a maximum differential nonlinearity (DNL) of -0.33/+0.56 LSB, maximum integral nonlinearity (INL) of -0.61/+0.55 LSB, effective number-of-bits (ENOB) of 8.8, and a power consumption of 9-μW. © 2014 IEEE.
News Article | April 5, 2016
Another causation theory for the melting of Greenland's ice sheet might have been ascertained by a new study carried out by a team of researchers from Denmark and Canada's York University. Over and beyond the blazing rays of the sun, warm and moist air might also be immensely responsible for the melting of the ice sheet. There were two major ice melts that occurred in 2012, according to the study. One took place from July 8 to July 11, and the other happened later that very month, from July 27 to July 28. Based on the automatic weather station data from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) and observations made, during these specific melt incidents, unusual amounts of warm and moist air impacted the surfaces of the ice sheet. By analyzing data from 12 different sites, researchers evaluated the varied energy sources responsible for the exceptional ice melt rates that occurred in 2012. They particularly found that the energy originating from warm air containing moisture content, not the sun's own radiant energy, could be held more accountable for the drastic ice melts. Incredibly, the melt that happened during those six days in July alone accounted for 14 percent of the overall melt that happened during the melting season. The record-high melt rate of 28 centimeters (11 inches) per day was observed during this period. Analysis of the data helped researchers arrive at the supposition that warm and moist air might be one of the key contributing forces toward the causation of the ice melts. "Glaciological instrumentation capable of automatically recording the daily rate of melting in exceptional melt circumstances, where the ice surface lowers by close to 10 [meters] [approximately 33 feet] in a few months, has only emerged in the last decade or so, thanks to PROMICE," said study co-author William Colgan of the Lassonde School of Engineering at York University. "The detail of PROMICE observations is permitting new insights on brief, but consequential, exceptional melt events." PROMICE was initiated in 2007 by the Danish Energy Agency's Danish Cooperation for Environment in the Arctic (DANCEA) program as an ongoing effort to assess changes in the Greenland ice sheet. The PROMICE automatic weather station data was used to estimate the varied impacts energy origination from the sun and atmosphere had on the ice melts. Greenland is the world's largest island and is host to the second largest ice mass on the planet, which covers a whopping 82 percent of the island. The details of the study have been published in the journal Geophysical Research Letters.
Lam J.C.W.,Queens University |
Lam J.C.W.,Lassonde |
Jain P.K.,Queens 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.
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.