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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

An Experimental Investigation of Dual-Injection Strategies on Diesel-Methane Dual-Fuel Low Temperature Combustion in a Single Cylinder Research Engine

Sohail, Aamir 14 August 2015 (has links)
The present manuscript discusses the performance and emission benefits due to two diesel injections in diesel-ignited methane dual fuel Low Temperature Combustion (LTC). A Single Cylinder Research Engine (SCRE) adapted for diesel-ignited methane dual fuelling was operated at 1500 rev/min and 5 bar BMEP with 1.5 bar intake manifold pressure. The first injection was fixed at 310 CAD. A 2nd injection sweep timing was performed to determine the best 2nd injection timing (as 375 CAD) at a fixed Percentage Energy Substitution (PES 75%). The motivation to use a second late injection ATDC was to oxidize Unburnt Hydrocarbons (HC) generated from the dual fuel combustion of first injection. Finally, an injection pressure sweep (550-1300 bar) helped achieve simultaneous reduction of HC (56%) and CO (43%) emissions accompanied with increased IFCE (10%) and combustion efficiency (12%) w.r.t. the baseline single injection (at 310 CAD) of dual fuel LTC.
202

Morpho-Physiological Characterization of Cotton Chromosome Substitution Lines for Abiotic Stresses

Awasthi, Akansha 09 December 2016 (has links)
The chromosome substitution (CS) lines constitute an important genetic and breeding resources, increasing the genetic diversity of Upland cotton from other alien tetraploid species. Two experiments were conducted to quantify low temperature and drought stress effects during early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22°C) and low (22/14°C) temperatures under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water and drought conditions. Above- and below-ground growth parameters including several root traits were assessed at 25 days after seeding. CS-lines varied significantly varied for many traits measured. Combined low temperature and drought response indices, derived from all measured parameters, showed CS-T04 and CSB08sh showed significantly higher and lower tolerance to low temperature, respectively, while CS-T04 and CS-B22sh showed significantly higher and lower tolerance to drought condition compared to TM-1.
203

Partial Nitration/anammox process in the moving bed biofilm reactor operated at low temperatures

Sultana, Razia January 2014 (has links)
<p>QC 20140527</p>
204

Cellulose liquefaction under mild conditions

Sabade, Sanjiv B. (Sanjiv Balwant) January 1983 (has links)
No description available.
205

Effects of low temperature applied at early growth stages on pepper development and anatomy (Capsicum annuum L. cv Lady Bell)

Clavijo, Claret Michelangeli de January 1990 (has links)
No description available.
206

A comparison of different heating and cooling energy delivery systems and the Integrated Community Energy and Harvesting system in heating dominant communities

Sullivan, Brendan January 2020 (has links)
The building sector is one of the largest consumers of energy and producers of greenhouse gas emissions in Ontario, representing 13% of the province’s emissions. Recently, countries have been looking to decrease their emissions in response to climate change. The electrification of space heating and domestic hot water preparation has gained traction in reducing emissions in countries with low emission electricity grids. This thesis proposes a novel energy delivery system called the Integrated Community Energy and Harvesting (ICE-Harvest) system. The ICE-Harvest system is a modified 5th Generation District Heating and Cooling (5GDHC) system. An ICE-Harvest system, much like a 5GDHC system, is a district energy system that incorporates heat pumps to couple the thermal and electrical energy demands of buildings. The ICE-Harvest system uses heat pumps to supply both heating and cooling from a one pipe thermal distribution network. The ICE-Harvest system has unidirectional mass flow in a ring arrangement with branches at each building. Bidirectional energy flow between the network and buildings is permitted, meaning that heat rejection from cooling processes can be recovered in the network to reduce the total system heating load. This concept is referred to as energy sharing. The energy needs of the network, and thus the buildings, are serviced through a centralized generation station referred to as the Energy Management Center (EMC). The EMC regulates the supply temperature of the network to the controlled setpoint. Within the EMC, the primary generation source is a Combined Heat and Power (CHP) unit. The purpose of this CHP is to offset the existing centralized natural gas generators on the Ontario electrical grid. These gas generators operate intermittently and inefficiently as a form of dispatchable generation to stabilize the provincial electrical grid. In this research, it is proposed that ICE-Harvest systems with on-site CHPs could replace these gas generators while providing the same support to the electrical grid at a much higher energy utilization ratio. For an accurate comparison, the CHP is constrained to only turn on according to the electricity system operator's gas generator dispatching schedule. An auxiliary boiler is included in the EMC to provide heat when the CHP is not permitted to operate. However, the possibility for Thermal Energy Storage (TES) to replace this boiler is also explored. An ICE-Harvest system's ideal design depends on the market conditions, building energy demands, and available waste energy sources. This research presents an ICE-Harvest system in a heating demand dominated community located in Ontario, Canada. The community consists of five buildings. The ICE-Harvest system is compared to conventional and alternative building energy systems using the energy consumption data of these buildings. The systems are compared according to their energy consumption, emissions produced, and impact on the electrical grid at both the distribution and transmission levels. The topic of using thermal energy storage in ICE-Harvest systems is also discussed, and a parameter sweep is performed on the thermal energy storage capacity. The results show that the ICE-Harvest system offers demand management opportunities to electricity system operators, substantially reduces annual emissions, and offers improved energy utilization compared to conventional systems. / Thesis / Master of Applied Science (MASc)
207

Developing Simple Lab Test To Evaluate HMA Resistance To Moisture, Rutting, Thermal Cracking Distress

Zhu, Feng 12 May 2008 (has links)
No description available.
208

The Effect of Low Temperature on the Physico-Chemical Treatment of Domestic Wastewater

Maqsood, Rashid 12 1900 (has links)
<p> The effect of low temperature on the physico-chemical treatment (PCT) of domestic wastewater is examined with special emphasis placed on activated carbon adsorption. PCT is a recent processing scheme, wherein wastewater goes through sedimentation, precipitation, deep bed filtration and adsorption. In PCT, activated carbon adsorption takes the place of conventional biological treatment for organic removal.</p> <p> Both batch studies using powdered activated carbon (PAC) and continuous flow studies with granular activated carbon (GAC) on a pure compound, sodium dodecyl sulfate (SDS) and domestic wastewater from the Dundas, Ontario Water Pollution Control Plant were investigated.</p> <p> Theoretical analysis and batch feasibility studies indicate that the effect of low temperature on coagulation, flocculation and sedimentation were quite easily handled within established design parameters. Batch studies on PAC treatment show that the carbon floc is easily separable from wastewater with the aid of a small dosage of polyelectrolyte and high effluent quality is obtainable at temperatures ranging from 2° - 25°C.</p> <p> Granular activated carbon was evaluated first on a pure compound, SDS. Batch isotherms and kinetics were also conducted at the same time to determine parameters needed for continuous flow modelling. Results derived from this phase of the study indicate that the activation energy from column studies is quite low (approximately 3.0 kcal/mole). Close match is obtained between the theoretical model (a modification of Thomas' reaction kinetics) and experimental data.</p> <p> Finally PCT pilot plant studies on domestic wastewater were carried out, at 5°C and 25°C. Soluble organic carbon removal was in excess of that predicted by purely adsorption type phenomenon. This is attributed to microbial activity inside the carbon columns. Greater soluble organic removal was seen at 25°C than at 5°C. Denitrification inside the carbon columns was found to be quite significant, again with stronger denitrifying activity at 25°C than at 5°C. Microbiological investigation of the carbon from the exhausted columns revealed over 10^9 cells/cm^3) of GAC bed volume from the lead column at 25°C. Denitrifiers were also detected in the carbon. Iodine numbers were determined on used carbon, which indicated the exhaustion of activated carbon capacity. Organic removal, however, continued undiminished, due to bacterial activity.</p> <p> The study culminated with the development of a theoretical model incorporating bacterial activity. The results of column effluent profile, however, indicated great discrepancy between theoretical predictions and experimental observations. This was attributed to simplistic assumptions utilized in solving the fixed bed problem.</p> / Thesis / Master of Engineering (MEngr)
209

The Northwest Extension of the West Cycladic Detachment System, Attica, Greece

Coleman, Mark 10 January 2024 (has links)
In the central Aegean of Greece, metamorphic rocks have been brought to the surface along multiple detachment faults producing a series of core complexes. The detachment faults have been grouped into several detachment systems including the North and West Cycladic Detachment Systems. The timing and magnitude of displacement along individual detachment faults is variable, the faults exhumed footwall rocks with a range of metamorphic grades from different crustal depths. Geochronology (zircon (U-Th)/He and white mica ⁴⁰Ar/³⁹Ar analyses) was conducted to investigate the timing of activity along a paired detachment system exposed in the bedrock of Mt. Hymittos, Attic Peninsula, Greece. Taken together the geochronometers indicate the detachments of Hymittos were active from the late Oligocene to the late Miocene with both faults active during the middle Miocene. The ductile-to-brittle deformation of the structures, top-SSW kinematics, morphology of the massif, and metamorphic grade indicate that these detachments are extensions of the West Cycladic Detachment System. Additionally, the overlap in timing between the structures indicates that paired detachment systems can be coeval. Coeval displacement along separate detachment branches has important implications for strain partitioning within the crust and the development of detachment systems. Detrital zircon U-Pb geochronology was conducted on samples from exposures of the West Cycladic Detachment System on the Attic Peninsula. The results are compared to unpublished data from the Attic Peninsula and the Western Cyclades including Santorini. The analyses confirm the correlation of the footwall rocks of Hymittos to the Cycladic Blueschist Unit as well as evaluate several paleogeographic correlations for the Cycladic Blueschist Unit. The samples herein record significant recycling of Variscan zircon from the Cycladic Basement, strongly suggesting the proto-Cycladic Blueschist Unit was deposited atop the Cycladic Basement. The Pindos Zone of the Hellenides is the most likely paleogeographic equivalent to the Cycladic Blueschist Unit. Strengthening this correlation gives additional insight into the position of the proto-Cycladic Blueschist Unit which is important for understanding both the movement of Hellenic terranes through time, and the pre-subduction relationship(s) between the terranes that today comprise the Attic-Cycladic Complex. Finally, electron backscatter diffraction analysis was utilized to examine the mechanisms of deformation in a suite of calcitic and dolomitic marble mylonites from the detachments of Hymittos. This was used to shed light on the conditions under which these ductile-then-brittle structures deformed suggesting that dolomite deformed under lower to sub-greenschist facies conditions may be surprisingly weak when deforming by grain size sensitive processes. Dolomite is a major rock forming mineral and comprises significant parts of carbonate dominated terranes and (meta)sedimentary successions. The apparent weakness of dolomite reported herein suggests that under greenschist and sub-greenschist facies conditions dolomite may accommodate significant strain not predicted by experiments or commonly reported from the field. Together this thesis provides insight into detachment fault architecture, deformation processes and the pre-subduction dynamics and structural position of the geologic units exposed within the Attic-Cycladic Complex.
210

Tuning electrolyte-electrode interphases for low-temperature Li-ion batteries

Xu, Robin January 2023 (has links)
Lithium ion batteries (LIBs) are crucial for modern electronics and electric vehicles (EV). However,their electrochemical performance is facing challenges at low temperatures (e.g ≤ 0 °C) due to reducedLi+ kinetics and increased charge-transfer resistance. Given the growing dependence on LIBs for bothelectronics and EVs, especially in cold environments, it is imperative to address the low-temperaturelimitations. Thus, improving the low-temperature performance of LIBs is essential for the broaderadoption and further advancement of LIBs. To address these challenges, this thesis demonstrates thatsignificant improvement of electrochemical performance at low temperatures can be achieved by in-corporating Lithium difluoro(oxalato)borate (LiDFOB) as an additive into the baseline electrolyte forthe Li(Ni0.8Mn0.1Co0.1)O2(NMC811)∥Li cell.At a low temperature of -20 °C, the NMC811∥Li cell with the electrolyte containing 4 wt% LiDFOBexhibited an impressive discharge capacity of 125 mAh/g at 0.1C (1C = 2.0 mAh cm−2), representingabout 61.6% of the capacity delivered at 20 °C. In contrast, the cell with the baseline electrolyte de-livered negligible discharge capacity under the same conditions. This result emphasizes the functionsof LiDFOB as an electrolyte additive in enhancing the low-temperature performance of NMC811∥Licells. This work reveals the kinetics bottleneck of Li+ transport during charge/discharge processes atlow temperatures can be mitigated by tuning cathode-electrolyte interphase (CEI) through introducingadditive into the baseline electrolyte.To substantiate these findings, Electrochemical Impedance Spectroscopy (EIS) was employed to re-veal the significant decrease of interface resistance resulting from the addition of LiDFOB into thebase electrolyte. X-ray Photoelectron Spectroscopy (XPS) further confirmed the benefits of LiDFOB,indicating that a B-rich, more conductive and thinner CEI formed on the NMC811 cathode induced byLiDFOB. The results indicate that the inclusion of LiDFOB in the baseline electrolyte is advantageousin tuning CEI at the cathode for reducing charge-transfer resistance and enhancing electrochemicalperformance.In conclusion, the tuned CEI induced by LiDFOB additive plays an important role in improving thelow-temperature performance of the NMC811∥Li cells. This improvement in the capacity delivery at-20 °C can be attributed to the formation of a highly conductive and uniform and thinner CEI layer,which in turn facilitates reduced charge-transfer resistance at low temperatures. This work sheds newlight on the electrolyte design with additives to develop high-performance LIBs operating at extremeconditions.2

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