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Title: ANALYSIS AND CONTROL OF COMPRESSION-IGNITION AND SPARK-IGNITED ENGINES OPERATING WITH DUAL-FUEL COMBUSTION STRATEGY
Creator: Kassa, Mateos
Date: 2017, 2017-07
Description: In recent years, the implementation of a dual-fuel combustion strategy has been explored as a means to improve the thermal efficiencies of...
Show moreIn recent years, the implementation of a dual-fuel combustion strategy has been explored as a means to improve the thermal efficiencies of internal combustion engines while simultaneously reducing their emissions. The dual-fuel combustion strategy was introduced in compression ignition engines to control the combustion phasing by varying the proportion of two simultaneously injected fuels, and altering the combustion timing. The dual-fuel injection strategy also allowed to extend the load limitation of advanced combustion engines, since the two injected fuel ignite in succession reducing the high peak pressures that generally act as a limiting factor. In spark-ignited (SI) engine, the implementation of a dual-fuel combustion strategy serves as an alternative approach to avoid knock (the inadvertent auto-ignition of the fuel mixture). Although conventional engines rely on delaying spark timing to avoid knocking cycles (which significantly reduces the thermal efficiency), the dual-fuel SI engine rely on the simultaneous injection of a low knock resistance and high knock resistance fuel to dynamically adjust the fuel resistance to knock as required. The dual-fuel SI engine thereby successfully suppresses knock without compromising the engine efficiency. Despite the benefits of the dual-fuel combustion strategy, several challenges arise in its implementation, especially when it is implemented along with other advanced combustion strategy leveraging variable valve timing, exhaust gas recirculation, turbocharging, and so forth. This study explores some of these challenges and addresses them from a control standpoint. Cylinder-to-cylinder variations is identified as one of the main challenges. An in-cylinder oxygen estimation strategy and modification to the conventional fueling strategy are proposed as approaches to reduce the combustion variations. In SI engines, the valve dynamics in transient operations are shown to negatively impact the dual-fuel control strategy. The effect of the valve timing on knock propensity and the resulting effect on the fueling strategy is investigated. Finally, the dual-fuel SI engine relies on measurements of the combustion intensity to adjust the fuel split between the low RON and high RON fuel. The implementation of a conventional knock control is shown to be counterintuitive for dual-fuel SI engines due to the highly reactive nature of the controller and the deterministic approach that assumes cycle-to-cycle correlation of the combustion intensity. Statistical investigation of the combustion intensity metric is conducted to identify key properties that can be leveraged for more effective control strategy.
Ph.D. in Mechanical, Material and Aerospace Engineering
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Title: POWDER CHARACTERIZATION AND PROCESS OPTIMIZATION FOR COLD COMPACTION AND SINTER APPLICATIONS OF COMMERCIALLY PURE TITANIUM POWDERS
Creator: Araci, Kerem
Date: 2011-08, 2011-07
Description: Near net shape manufacturing using powder metallurgy (P/M) technology and processes can significantly reduce material waste and cost during...
Show moreNear net shape manufacturing using powder metallurgy (P/M) technology and processes can significantly reduce material waste and cost during component fabrication. This study includes all the efforts to evaluate near net shape consolidation processes utilizing several different commercially pure titanium (CP-Ti) powders, focusing on the one produced by Armstrong Process® technology. Powder characteristics were studied in terms of morphology, particle size distribution, apparent and tap densities, and chemistry. Desired particle size distributions and higher powder densities were observed for HDH powders, while unique coral-like morphology was examined for the Armstrong Process® powder. Ball milling of the Armstrong Process® powder was systematically investigated by evaluating the impact on the particle size distribution, powder density and chemistry. Cold-uniaxial compaction of the milled powders was also evaluated in terms of theoretical density and green strength as a function of compaction pressure and lubrication techniques. Green densities were varied from 79 % to 91% for different powder compacts in different compaction conditions. Excellent green compaction of 145 MPa was approached by green compacts of Armstrong Process® powder. Sinter processing of the green compacts was investigated to approach relatively advanced tensile and flexural properties as a function of process temperature, time and heating rate. Near net-shape components which were fabricated by pressing and sintering were shown to achieve near-full densification with up to 97% of the theoretical density. Properties of P/M materials after the consolidation process were characterized and compared to those of conventionally produced materials.
M.S. in Materials Science and Engineering, July 2011
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Title: CLOSED-LOOP CONTROL GUST SUPPRESSION AT OF LIFT FOR LONGITUDINAL LOW REYNOLDS NUN4BERS
Creator: Kerstens, Wesley
Date: 2011-07-26, 2011-07
Description: Experiments are conducted to investigate the ability of variable pressure, pulsed-blowing actuators and zero-net-mass-flux actuators to...
Show moreExperiments are conducted to investigate the ability of variable pressure, pulsed-blowing actuators and zero-net-mass-flux actuators to maintain a constant lift force on a low aspect ratio, semi-circular wing in a longitudinally gusting flow. Dynamic models of the lift response to actuation and the lift response to longitudinal gusting are obtained through modern black-box system identification methods. Robust, H∞, closed-loop controllers are synthesized using a mixed sensitivity, loopshaping approach. An additional feed-forward disturbance compensator is designed based on a model of the unsteady aerodynamics. The controllers show suppression of lift fluctuations at low gust frequencies, f < 1Hz (reduced frequency, k < 0.09). At higher frequencies, the control performance degrades due to limitations related to the time for a disturbance, created by the actuators, to convect over the wing and establish the flow field that leads to enhanced lift on the wing. Similar limitations are observed for both wings even though the bandwidth of the zero-net-mass-flux actuators is an order of magnitude higher than that of the pulsed-blowing actuators.
M.S. in Mechanical and Aerospace Engineering, July 2011
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Title: Converter steel foundry practice
Creator: Mouat, Harry G.
Date: 2009, 1920
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/convertersteelfo00moua
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaf 78

Title: Construction and comparative test of a four cycle gasoline engine arranged to operate with and without an augmented charge of air
Creator: Stump, Dan Monroe
Date: 2009, 1913
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/constructioncomp00stum
Thesis (B.S.)--Armour Institute of Technology

Title: Effect on entrapped air on the action of wet pipe alarm valves
Creator: Ahern, A. J., Mckarahan, E. V., Oberfelder, W. S., Tregay, Jno
Date: 2009, 1909
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectonentrappe00aher
Thesis (B.S.)--Armour Institute of Technology

Title: Effect of varying speed upon the gas consumption of the westinghouse gas engine
Creator: Glos, H. V, Latta, S. H, Pahlman, P. J
Date: 2009, 1908
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofvaryings00glos
Thesis (B.S.)--Armour Institute of Technology, 1908 B.S. in Mechanical Engineering, 1908

Title: The effect of throttling suction on a three-inch Dayton centrifugal pump
Creator: Mcauley, B.f., Spitzglass, J. M.
Date: 2009, 1909
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofthrottli00mcau
Thesis (B.S.)--Armour Institute of Technology

Title: An effect of the stratification of gases in a gas engine
Creator: Schmieman, Oscar George, Spencer, Charles Henry, Jr
Date: 2009, 1913
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofstratifi00schm
Thesis (B.S.)--Armour Institute of Technology

Title: Effect of varying compression on the efficiency of a Fairbanks-Morse horizontal gas engine
Creator: Bergbom, A. S, Hoffman, R. J.
Date: 2009, 1910
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofvaryingc00berg
Thesis (B.S.)--Armour Institute of Technology, 1910 B.S. in Mechanical Engineering, 1910

Title: Effect of the variation of initial and back pressure on the economy of a simple, high speed, automatic steam engine
Creator: Boehmer, Alexander Henry, Wells, John Barnard
Date: 2009, 1907
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofvariatio00boeh
Thesis (B.S.)--Armour Institute of Technology

Title: The effect of variation of compression on the efficiency and economy of a gas engine
Creator: Grassby, G. A., Jr, Hall, A. G.
Date: 2009, 1909
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/effectofvariatio00gras
Thesis (B.S.)--Armour Institute of Technology

Title: Flow of heat through pipe covering
Creator: Schwartz, Frank H., Zemke, Arthur W.
Date: 2009, 1920
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/flowofheatthroug00schw
Thesis (B.S.)--Armour Institute of Technology

Title: The floor distribution of water from automatic sprinkler heads
Creator: Goppelsroeder, Roy A. C., Peterson, Leonard A, Grasse, C. A.
Date: 2009, 1916
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/floordistributio00gopp
Thesis (B.S.)--Armour Institute of Technology

Title: Floor distribution of standard automatic sprinkler heads
Creator: Kula, J. S., Foschinbaur, L. A., Schreiner, R. F.
Date: 2009, 1917
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/floordistributio00kula
Thesis (B.S.)--Armour Institute of Technology

Title: CYCLIC THERMAL TREATMENT
Creator: Gu, Sijie
Date: 2015, 2015-12
Description: Cyclic thermal treatment has the potential to improve energy efficiency of thermal processing. It has been shown that in some cases, the...
Show moreCyclic thermal treatment has the potential to improve energy efficiency of thermal processing. It has been shown that in some cases, the productivity was enhanced by the cyclic thermal treatment operation. In order to investigate the cyclic thermal treatment effect, Copper-Nickel interdiffusion couples were investigated. When the Cu-Ni interdiffusion couple showed positive results, the cyclic thermal treatment was applied to pack carburization and gas carburization of steel. The Cu-Ni interdiffusion couples were annealed with different time-temperature profiles for 5 days. There are three types of time-temperature profile; isothermal, symmetric, and asymmetric cyclic thermal treatment. After thermal treatment, concentration-distance profiles were. Based on the concentration-distance profile, the interdiffusion coefficients of different time-temperature profiles were calculated. The interdiffusion coefficient of the diffusion couple with a ramp rate of 1°C/min had a higher diffusion coefficient than that of the diffusion couple annealed isothermally at the equivalent temperature, 863°C, which means that cyclic thermal treatment has the effect of accelerating diffusion. When the ramp rate was 5ºC/min interdiffusion coefficients were higher than that of the diffusion couple annealed isothermally at the maximum temperature. However, when the ramp rate was increased to 10°C/min, the diffusion coefficient decreased to almost the same as the interdiffusion coefficient of the diffusion couple at the equivalent temperature. After achieving a promising result for the Cu-Ni diffusion couples, we expanded the cyclic thermal treatment to carburizing. The temperature range for cyclic pack carburization was 850° to 950°C. Increasing the cyclic ramp rate resulted in an increase in the case depth. Due to the setup of the pack carburization, the maximum cooling rate achievable is 5°C/min. In order to reach a higher ramp rate, an induction heating gas carburization system was setup. The temperature range for the cyclic induction heat gas carburization was 850°C to 950°C. For the cyclic induction heat gas carburization with increase in ramp rate, the case depth increased. The sample induction gas carburized at a ramp rate of 20°C/min had a deeper case depth than the sample induction gas carburized isothermally at 904.4°C, the equivalent temperature. The first test showed the sample induction gas carburized with a ramp rate of 20°C/min had a deeper case depth than the sample induction gas carburized isothermally at 950° C. With this we draw the conclusion that the cyclic induction gas carburization can achieve a deeper case depth than the isothermal at equivalent temperature induction gas carburization.
Ph.D. in Materials Science and Engineering, December 2015
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Title: Grinnell variable pressure alarm valve
Creator: Eyers, Walter, Thomson, F. L.
Date: 2009, 1908
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/grinnellvariable00eyer
Thesis (B.S.)--Armour Institute of Technology, 1908 B.S. in Fire Protection Engineering,...
Show morehttp://www.archive.org/details/grinnellvariable00eyer
Thesis (B.S.)--Armour Institute of Technology, 1908 B.S. in Fire Protection Engineering, 1908
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Title: Humidifying air in living rooms by attachments to the steam radiator
Creator: Andre, G. L.
Date: 2009, 1918
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/humidifyingairin00andr
Thesis (B.S.)--Armour Institute of Technology; Biblography: leaf 60

Title: A NANO-STRUCTURED CERAMIC/POLYMER COMPOSITE FILM FOR ELECTRONIC INTERCONNECTIONS
Creator: Harwath, Frank
Date: 2016, 2016-05
Description: Separable electrical interconnections are a ubiquitous part of modern life and for technical reasons are currently based on the use of gold....
Show moreSeparable electrical interconnections are a ubiquitous part of modern life and for technical reasons are currently based on the use of gold. Since gold is a commodity and subject to significant price fluctuations there is a need for separable interconnects not based on gold. Polymer/ceramic films were produced from various polymer precursors with loadings of multi-wall nanotubes (MWNT) and inert fillers. A variety of applications means were employed with the best success being achieved by means of a modified doctor blade. Pyrolysis was conducted in an inert atmosphere at 1 bar at a range of temperatures in a tube furnace. Pyrolysis was also conducted using a fiber laser. The modulus of the film is estimated to be 71.8 MPa with an ultimate tensile strength of 179 MPa based on hardness tests and anisotropic crack dimensions which developed as a result of uniaxial stress induced during application of the precursor. Uniaxial stress improved film adhesion regardless of filler type or level. Modification of film characteristics after pyrolysis was attempted using spark plasma sintering (SPS). Electrical testing displayed a percolation threshold above loadings of 1% (wt) of MWNTs where there is a significant drop in electrical resistivity. Further reductions in contact resistance were demonstrated up to 2% loading of MWNTs. The level of contact resistance achieved (<10) for a separable contact, in conjunction with a gold plated contact representative of most electronic connectors, indicates that an acceptable level of contact resistance may be achieved using these materials. Characterization of the film using attenuated total reflectance (ATR), xray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy point to a morphology which is dominated by crystallites joined by regions of aliphatic carbon chains. Work function measurements were consistent with highly ordered pyrolytic graphite. (HOPG)
Ph.D. in Materials Science and Engineering, May 2016
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Title: High speed tool steel on lathe work
Creator: Hayes, C. E., Wilson, F. N.
Date: 2009, 1906
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/highspeedtoolste00haye
Thesis (B.S.)--Armour Institute of Technology

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