Xu T.,Consulting Inc. |
Lien F.-S.,University of Waterloo |
Ji H.,Consulting Inc. |
Zhang F.,DRDC Suffield
Shock Waves | Year: 2013
A dense, solid particle flow is numerically studied at a mesoscale level for a cylindrical shock tube problem. The shock tube consists of a central high pressure gas driver section and an annular solid powder bed with air in void regions as a driven section with its far end adjacent to ambient air. Simulations are conducted to explore the fundamental phenomena, causing clustering of particles and formation of coherent particle jet structures in such a dense solid flow. The influence of a range of parameters is investigated, including driver pressure, particle morphology, particle distribution and powder bed configuration. The results indicate that the physical mechanism responsible for this phenomenon is twofold: the driver gas jet flow induced by the shock wave as it passes through the initial gaps between the particles in the innermost layer of the powder bed, and the chaining of solid particles by inelastic collision. The particle jet forming time is determined as the time when the motion of the outermost particle layer of the powder bed is first detected. The maximum number of particle jets is bounded by the total number of particles in the innermost layer of the powder bed. The number of particle jets is mainly a function of the number of particles in the innermost layer and the mass ratio of the powder bed to the gas in the driver section, or the ratio of powder bed mass (in dimensionless form) to the pressure ratio between the driver and driven sections. © 2013 Her Majesty the Queen in Right of Canada.
Lien F.-S.,University of Waterloo |
Xu T.,University of Waterloo |
Zhang F.,DRDC Suffield
AIP Conference Proceedings | Year: 2012
The mechanism of the instability in heterogeneous post-detonation flows, which contain dense solid particles, is yet to be determined due to its physical complexity. Since both strain rate and vorticity are found to play an important role in the particle agglomeration processes, a new criterion is established to represent the tendency of particle agglomeration, either based on divergence of particle velocity related to the difference between strain-rate and vorticity invariants or time derivative of particle volume fraction. The particle jetting phenomenon observed in a heterogeneous explosion is simulated and investigated at mesoscales based on the same numerical platform, which paves the way to investigate the role of vorticity, strain-rate and turbulence in the formation of macroscopic particle jetting. © 2012 American Institute of Physics.
News Article | January 6, 2016
A recurring Alberta theme the past decade, in some circles, albeit for the most part seen as little more than a public relations exercise, has been the oil sands as revenue stream for Canada’s transition from petrostate to “green energy superpower”. For example, in his 2009 book Green Oil: Clean Energy for the 21st Century?, author Satya Das suggested revenue from $15-trillion worth of oil sands could be used to finance a green Canadian future. Unfortunately, in today’s world, that $15 trillion looks like a mirage even as the prospects for a green future and the need to finance that future becomes increasingly certain. As Albert’s Environment Minister, Shannon Phillips, recently pointed out, “We are entering a world that is going to be constrained with respect to carbon.” The extent of that constraint however is probably far greater than most Canadian, particularly Alberta, politicians would care to admit. At the recently concluded Paris climate talks Canada’s Environment Minister, Catherine McKenna, endorsed a call to hold global warming to no more than 1.5 degrees Celsius above pre-industrial levels and that call was heeded with the concluded agreement to keep “well below” 2 degrees. Even keeping to 2 degrees, a study lead by Christophe McGlade of University College London suggests, would require foregoing the burning of a third of the world’s oil reserves, half of its gas reserves and keeping over 80 per cent of the coal remaining in the ground and of the burnable oil virtually none would come from the Alberta oil sands due to the high cost and high emissions associated with their recovery. Instead of having trillions to spend to develop renewable energy and fulfill their Paris commitments to the environment, here and here, the Alberta government projects a budget deficit of $6.1 billion for fiscal 2015-16 and $18 billion in total over the next 4 years and the newly elected federal Liberal government of Canada says the $2.3-billion surplus projected by the previous Conservative government for this year is more likely to be a $3-billion deficit on top of the $10 billion deficits they promised during the election campaign to run each of the next three years to kick-start the Canadian economy through infrastructure spending. A large part of the revenue shortfall of both governments has come about as a result of the slump in oil prices from about $60 US per barrel a year ago to less than $40 today. Canada is the 5th greatest producer of oil and has the 3rd largest reserves but that doesn’t mean much to the Canadian taxpayer or the provincial owners of the resource when the cost of production is higher than the market value of the oil and when the 2nd largest, and lowest cost oil producer, is set on undercutting the competition to ensure it has nothing left in the ground once the environmental limits to burning fossil fuels has been reached. Alberta and Canada as a whole are essentially petrostates absent the benefits of state control of the resource, the price it can demand for that resource or the revenue derived from its sale. The Alberta Heritage Savings Trust Fund is essentially a sovereign wealth fund; the only one in the country, but of the close to $200 billion in non-renewable resource revenue that has been generated since its inception in 1976 the value of the fund, as of March 31, 2014, was only $17.5 billion, less than the projected accumulated deficits for the province the next 4 years. Both the provincial and federal governments have pledged to reduce carbon emissions but their most vital concern is the advancement of the well-being of their citizens. For too long they have financed that advancement on the back of uncertain petroleum revenues that are now drying up and there is no immediate, recognized, replacement. Salvation, at least in the short run, would emerge in the form of technology that produces bitumen at no cost, without carbon emissions and that could generate sufficient revenue that the country and province could affordably transition away from the boom and bust cycle of the oil industry to a sustainable future. In the absence of such a miracle it is hard to see how the environmental undertakings of Canadian politicians can be financed. Australia, like Canada, depends heavily on resource extraction to finance its economy and both countries are confronted by similar economic realities. Former Australian Prime Minister Bob Hawke suggests that beyond the obvious alternatives of reducing expenditures, increasing taxes or some combination of the two, in the face of the new reality, there is another alternative; a new source of revenue, which for Australia he suggests should be taking the world’s nuclear waste. In other words he is prepared to be innovative in the face of stark reality. There are vast, remote and dry regions of Australia, which is a stable democracy thus it is an ideal location for storing spent nuclear fuel; a service for which a global clientele appears to be willing to pay in the vicinity of $100 billion dollars (about double the projected deficits of Canada and Alberta over the next 4 years). Canada is also a stable democracy. Rather than being dry however it has large tracts of bitumen, a recognized sealant for underground repositories, into which the world’s waste can be placed, for a fee. Over the long term the heat and ionization radiation of that waste would cause the highly viscous bitumen to flow to a producing well and split some of the low grade bitumen molecules into more valuable fractions. Further information regarding the nuclear assisted hydrocarbon production method is available here and here. It is likely such an effort would have to be federally controlled and there is a precedent, the Suffield Experimental Station. DRDC Suffield was a research facility established in 1941 as a joint British/Canadian biological and chemical defence facility. It is a 2690 square kilometer block of land in southeastern Alberta that by the end of the Second World War housed 584 personnel trained in chemistry, physics, meteorology, mathematics, pharmacology, pathology, bacteriology, physiology, entomology, veterinary science, mechanical and chemical engineering. This land was expropriated by the Province of Alberta on behalf of the Canadian Federal Government to which it was leased for ninety-nine years at a cost of one dollar per year to support the war effort. Suffield is an area within which efforts were undertaken that would today be seen as no less controversial or dangerous than the disposal of nuclear waste. After the war the block was transferred from the province to the federal government in exchange for a large number of army and air camps and buildings from the Dominion Government and it has subsequently been used for large, experimental, chemical and explosive efforts and training. In 1974 the federal and provincial governments signed a surface access agreement for the purpose of developing petroleum reserves in the area and subsequently 14,000 oil and gas wells have been drilled on the site, mostly by the Alberta Energy Company (AEC) which was formed at the height of the OPEC oil embargo, with provincial government support. The province held 50 percent of the initial shares in an effort intended to try and lessen dependence on foreign oil. Today that same oil is undercutting the oil sands and many see climate change as no less a threat than was faced in the middle of the twentieth century. Subsequently the province divested its interest in AEC, which became one of Canada’s largest private-sector independent oil and gas exploration and production companies prior to merging with PanCanadian Energy Corporation in 2002 to form Encana. There is every reason to suspect nuclear waste disposal and bitumen recovery from using the heat of spent nuclear fuel, on expropriated lands, can today be every bit as lucrative a proposition. The private sector aren’t about to take on such an effort, at least not initially and it doubtful there will be any major, new, oil sands efforts in any event as things currently stand. Besides a private initiative isn’t likely to turn around and funnel revenues into an energy source that can actually unrealized the radiative imbalance created by global warming by moving surface heat through a heat engine into the ocean abyss; an effort that can unwind the damage caused by the burning of fossil fuels (see here and here) and fulfill the commitment to a 1.5 degree temperature increase. The Alberta and Canadian governments have every opportunity to live up to their commitments. All that is required is the expenditure of a little political capital and some initiative. It would be far better that we pay are way into the future we want for our children rather than finance that future with debt for which our children will ultimately be responsible.
Diakowski P.M.,University of Western Ontario |
Xiao Y.,University of Western Ontario |
Petryk M.W.P.,DRDC Suffield |
Kraatz H.-B.,University of Western Ontario
Analytical Chemistry | Year: 2010
A recognition layer formed by multiwalled carbon nanotubes (MWCNTs) covalently modified with a ferrocene?lysine conjugate deposited on the indium tin oxide (ITO) was investigated as a sensor for chemical warfare agent (CWA) mimics. Electrochemical impedance spectroscopy measurements showed that upon addition of CWA mimic dramatic changes occurred in the electrical properties of the recognition layer. These changes allowed the detection of nerve agent analogues at the micromolar level, and a limited sensitivity was observed toward a sulfur mustard mimic. Experimental parameters were optimized so as to allow the detection of CWAs at single frequency, thereby significantly reducing acquisition time and simplifying data treatment. A proposed method of detection represents a significant step toward the design of an affordable and "fieldable" electrochemical CWA sensor. © 2010 American Chemical Society.
Collier J.,DRDC Suffield |
Se S.,MDA Systems Ltd. |
Kotamraju V.,MDA Systems Ltd.
Proceedings - 2013 International Conference on Computer and Robot Vision, CRV 2013 | Year: 2013
This paper describes a multi-sensor appearance-based place recognition system suitable for robotic mapping. Unlike systems that extract features from visual imagery only, here we apply the well known Bag-of-Words approach to features extracted from both visual and range sensors. By applying this technique to both sensor streams simultaneously we can overcome the deficiencies of each individual sensor. We show that lidar-based place recognition using a generative model learnt from Variable Dimensional Local Shape Descriptors can be used to perform place recognition regardless of lighting conditions or large changes in orientation, including traversing loops backward. Likewise, we are still able to exploit the feature rich place recognition that visual systems provide. Using a pose verification system we are able to effectively discard false positive loop detections. We present experimental results that highlight the strength of our approach and investigate alternative techniques for combining the results from the individual sensor streams. The multi-sensor approach enables the two sensors to complement each other well in large urban and rural environments under variable lighting conditions. © 2013 IEEE.
Scherbatiuk K.,DRDC Suffield |
Rattanawangcharoen N.,University of Manitoba
International Journal of Impact Engineering | Year: 2010
This study is aimed to provide an efficient analytical model to calculate a time history of response for a free-standing soil-filled HESCO Bastion concertainer® wall subjected to air blast loading. The model is formulated based on the observations of the wall response to air blast loading in the experiments and on the deformation of a finite element model. This hybrid rigid body rotation model combines both a reverse Winkler foundation to model the distribution of pressure at the base of the wall and perfectly plastic shear resistance to model the shear deformation at the corner. The time histories of horizontal and vertical displacements calculated from the proposed analytical model are validated with displacements from both full-scale blast testing of free-standing simple straight walls and calculations using a finite element model. © 2009 Elsevier Ltd.
Scherbatiuk K.,DRDC Suffield |
Rattanawangcharoen N.,University of Manitoba
International Journal of Impact Engineering | Year: 2011
The objective of this study is to provide an efficient analytical model to calculate a time history of impulsive response for a free-standing soil-filled HESCO Bastian concertainer® wall subjected to a known air blast loading, and to improve upon the formulation of a hybrid rigid-body rotation model previously published. The earlier model did not take into account sliding, which occurs for HB walls filled with cohesive soils. Any lateral movement along the base of the wall was assumed to result entirely from shear deformation. In this paper, the sliding effect is derived and incorporated into the model. The formulation of this proposed hybrid rigid-body rotation model with sliding is presented in detail. The time histories of horizontal and vertical displacements calculated from the proposed analytical model are validated with results from full-scale blast testing of free-standing simple straight walls and calculations using a finite element model for both cohesive and cohesionless soil properties. A sensitivity study was conducted to test the model's response to different soil parameters by comparing the finite element model and proposed analytical model. The proposed analytical model predicts changes in displacement-time histories of similar magnitudes compared with those predicted by the finite element model, showing that the proposed analytical model's response correctly considers changes in response occurring from differing soil parameters. Height-to-width ratios are presented for its range of validity. © 2011 Published by Elsevier Ltd. All rights reserved.
Christopher M.E.,DRDC Suffield |
Wong J.P.,DRDC Suffield
Anti-Inflammatory and Anti-Allergy Agents in Medicinal Chemistry | Year: 2011
Respiratory RNA viruses are constantly evolving, thus requiring development of additional prophylactic and therapeutic strategies. Harnessing the innate immune system to non-specifically respond to viral infection has the advantage of being able to circumvent viral mutations that render the virus resistant to a particular therapeutic agent. Viruses are recognized by various cellular receptors, including Toll-like receptor (TLR) 3 which recognizes doublestranded (ds)RNA produced during the viral replication cycle. TLR3 agonists include synthetic dsRNA such as poly (IC), poly (ICLC) and poly (AU). These agents have been evaluated and found to be effective against a number of viral agents. One major limitation has been the toxicity associated with administration of these drugs. Significant time and effort have been spent to develop alternatives/modifications that will minimize these adverse effects. This review will focus on the TLR3 agonist, poly (IC)/(ICLC) with respect to its use in treatment/prevention of respiratory viral infections. © 2011 Bentham Science Publishers.
D'Agostino P.A.,DRDC Suffield
NATO Science for Peace and Security Series A: Chemistry and Biology | Year: 2011
Solid phase microextraction (SPME) fibers were used to headspace-sample chemical warfare agents and their hydrolysis products from glass vials and glass vials containing spiked media, including Dacron swabs, office carpet, paper and fabric. The interface of the Z-spray source was modified to permit safe introduction of the SPME fibers for desorption electrospray ionization mass spectrometric (DESI-MS) analysis. A "dip and shoot" method was also developed for the rapid sampling and DESI-MS analysis of chemical warfare agents and their hydrolysis products in liquid samples. Sampling was performed by simply dipping fused silica, stainless steel or SPME tips into the organic or aqueous samples. Replicate analyses were completed within several minutes under ambient conditions with no sample pre-treatment, resulting in a significant increase in sample throughput. The developed sample handling and analysis method was applied to the determination of chemical warfare agent content in samples containing unknown chemical and/or biological warfare agents. Ottawa sand was spiked with sulfur mustard, extracted with water and autoclaved to ensure sterility. Sulfur mustard was completely hydrolysed during the extraction/autoclave step and thiodiglycol was identified by DESI-MS, with analyses generally being completed within 1 min using the "dip and shoot" method. © 2011 Springer Science+Business Media B.V.
D'Agostino P.A.,DRDC Suffield |
Chenier C.L.,DRDC Suffield
Rapid Communications in Mass Spectrometry | Year: 2010
Desorption electrospray ionization mass spectrometry (DESI-MS) has been applied to the direct analysis of sample media for target chemicals, including chemical warfare agents (CWA), without the need for additional sample handling. During the present study, solid-phase microextraction (SPME) fibers were used to sample the headspace above five organophosphorus CWA, O-isopropyl methyl- phosphonofluoridate (sarin, GB), O-pinacolyl methylphosphonofluoridate (soman, GD), O-ethyl N,N-dimethyl phosphoramidocyanidate (tabun, GA), O-cyclohexyl methylphosphonofluoridate (cyclohexyl sarin, GF) and O-ethyl S-2-diisopropylaminoethyl methyl phosphonothiolate (VX) spiked into glass headspace sampling vials. Following sampling, the SPME fibers were introduced directly into a modified ESI source, enabling rapid and safe DESI of the toxic compounds. A SYNAPT HDMS™ instrument was used to acquire time-aligned parallel (TAP) fragmentation data, which provided both ion mobility and MSn (n = 2 or 3) data useful for the confirmation of CWA. Unique ion mobility profiles were acquired for each compound and characteristic product ions of the ion mobility separated ions were produced in the Triwave™ transfer collision region. Up to six full scanning MSn spectra, containing the [M+H]+ ion and up to seven diagnostic product ions, were acquired for each CWA during SPME fiber analysis. A rapid screening approach, based on the developed methodology, was applied to several typical forensic media, including Dacron sampling swabs spiked with 5μg of CWA. Background interference was minimal and the spiked CWA were readily identified within one minute on the basis of the acquired ion mobility and mass spectrometric data. © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.