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Title: NOVEL FAULT DIAGNOSTIC TECHNIQUE AND UNIVERSAL SENSOR FOR PERMANENT MAGNET ELECTRIC MACHINES USING SEARCH COILS
Creator: Da, Yao
Date: 2012-04-23, 2012-05
Description: Over the past decade, permanent magnet synchronous machines (PMSMs) have gained significant popularity in industry, such as wind turbines and...
Show moreOver the past decade, permanent magnet synchronous machines (PMSMs) have gained significant popularity in industry, such as wind turbines and electric vehicles, owing to their high efficiency, high output power to volume ratio, and high torque to current ratio. In these mission critical applications, an unexpected fault or failure of the machine could lead to very high repair or replacement cost, or even catastrophic system failure. Therefore a robust and reliable health monitoring and fault diagnostic approach is desired, which could help in scheduling preventive maintenance to lengthen their lifespan and avoid machine failure. This dissertation presents a novel multi-faults diagnostic approach using search coils. These search coils are wound around armature teeth, so they typically need to be installed during manufacturing. But its immunity to high frequency harmonics makes it suitable for inverter/rectifier fed motors or generators, such as wind turbines and automotive systems. In addition, this method does not require the knowledge of proprietary constructional details of the machine. Since the electromagnetic flux is directly measured in this method, it provides much more information than any other scheme: the direction of eccentricity and the location of shorted windings. Furthermore, this method is also capable of evaluating the severity of each fault, which is of significant importance in mission critical applications such as automotive, aerospace and military applications. In addition to these uses, the search coils can be used as a universal sensor to estimate phase current or rotor position, which are critical information in a PMSM close-loop control, which allow it to work as a backup sensor for fault tolerant operation. The proposed fault detection scheme and universal sensor concept have been tested under several scenarios with Finite Element Analysis and experimentally validated.
Ph.D. in Electrical Engineering, May 2012
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Title: CELL-MATRIX INTERACTIONS IN ADIPOSE TISSUE FUNCTION
Creator: Vaicik, Marcella K.
Date: 2015, 2015-07
Description: The overall goal of this work is to apply in vivo and in vitro models to study the basement membrane protein laminin α4 (lama4) in adipocyte...
Show moreThe overall goal of this work is to apply in vivo and in vitro models to study the basement membrane protein laminin α4 (lama4) in adipocyte function. Adipose tissue accumulation, lipogenesis, and structure were examined in mice with a null mutation of the lama4 gene (Lama4−/−) and compared to wild-type animals (Lama4+/+). The Lama4−/−mice phenotype was investigated to evaluate if the differences were due specifically to the adipose tissue function. Physical activity and food intake does not differ between Lama4+/+ and Lama4−/− mice. However, Lama4−/− mice have a significantly increased metabolic rate at 25°C and 16°C compared to Lama4+/+ mice. In contrast, in thermoneutral conditions at 30°C both Lama4+/+ and Lama4−/− mice exhibit equivalent metabolic rates. Interestingly, when room temperature housed mice fat pads were evaluated with immunohistochemistry, Lama4−/− mice exhibit significantly increased UCP-1 expression in subcutaneous adipose. These results suggest that beiging, white to brown adipocytes, in subcutaneous adipose tissue in Lama4−/− mice may lead to decreased adipose tissue accumulation and improved metabolic function. While animal models indicate the absence of lama4 results in more beiging in subcutaneous adipose tissue, an in vitro tissue engineered model was developed to study the adipocyte function in a controlled microenvironment. Primary cell spheroids developed from Lama4+/+ and Lama4−/− were incorporated into synthetic poly(ethylene glycol) (PEG) hydrogels within a range of stiffnesses. When the cells were given the same chemical cues their functions differed depending upon microenvironment stiffness. Beige function in adipocyte cells in 3D can be influenced by matrix stiffness. In conclusion, the laminin alpha 4 basement membrane protein absence in adipose tissue results in adipocyte functional changes in vivo. The Lama4−/− mice have resistance to diet induced weight gain and increased metabolic rate at room temperature and when cold challenged. The Lama4−/− mice had increased beiging in the subcutaneous depot. Additionally, a tissue engineered model was developed to further study cell-ECM interactions first identified in an animal model. These in vivo findings and the engineered model of adipose tissue have great potential for studying obesity and other adipose related diseases. Future work will require continued interdisciplinary collaboration towards the successful identification and screening of novel therapeutics using engineered tissue models.
Ph.D. in Biomedical Engineering, July 2015
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Title: Financial Incubators, India: panel copy
Creator: Shah, Shruti
Date: 2010-05-01, 2010-05

Title: A system of multiplex telephony by the use of vacuum tubes
Creator: Arnold, E. H., Throop, A. R.
Date: 2009, 1919
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/systemofmultiple00arno
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaves 44-45

Title: RECEIVER AUTONOMOUS INTEGRITY MONITORING AGAINST ORBIT EPHEMERIS FAULTS IN CARRIER PHASE DIFFERENTIAL GPS
Creator: Stevanovic, Stefan
Date: 2013-04-18, 2013-05
Description: This work investigates the potential of the Global Positioning System (GPS) to enable a safe approach for rendezvous applications including...
Show moreThis work investigates the potential of the Global Positioning System (GPS) to enable a safe approach for rendezvous applications including shipboard landing of military aircraft. GPS has been shown to have the necessary accuracy for such an operation, and could potentially replace the existing radar or laser based systems. [Kha08][WPF08]1 However, to ensure safe operation, GPS must also be able to avoid hazardous situations. Shipboard aircraft approach navigation is an example rendezvous application requiring both high accuracy and high integrity. In this work, GPS measurement error models and orbit ephemeris fault (OEF) detection algorithms are developed for rendezvous applications, and performance is analyzed for the aircraft shipboard landing application. Both reference station and user based monitors can be used for orbit ephemeris fault detection. The available reference monitors either require a stationary reference receiver, or cannot protect against all types of orbit ephemeris faults. As an alternative, this work develops and investigates the use of receiver autonomous integrity monitoring (RAIM), which is user-based. Two contrasting algorithms, differential RAIM (DRAIM) and relative RAIM (RRAIM) are derived and analyzed for a realistic shipboard landing application. DRAIM is most effective when the aircraft first begins the approach. On the other hand, RRAIM performs best near the end of the approach. Assessing integrity risk is shown to be a major challenge for the RRAIM algorithm. Thus, a new unified RAIM (URAIM) concept is introduced. It seamlessly integrates DRAIM and RRAIM into a single detection algorithm, and also facilitates integrity risk evaluation. This is because the URAIM measurement equation can be used for both position estimation as well as fault detection. 1Corresponding to references in the Bibliography. xii Since high accuracy is desired, fixing integer cycle ambiguities is required. The Enforced Position-Domain Integrity-Risk Cycle Resolution Algorithm (EPIC) method of integrity risk bounding is used along with the URAIM fault detection algorithm in what we call the EPIC-URAIM algorithm. In general, the OEF will interfere with the cycle resolution process. In this work, the EPIC integrity risk bound formula is modified to account for the presence of an OEF. The EPIC-URAIM algorithm is simulated for 1507 sea-based locations around the globe. An average global availability of accuracy and integrity of 98.6% is achieved. This work illustrates the feasibility of detecting orbit ephemeris faults with integrity, while simultaneously meeting stringent accuracy requirements for real-time rendezvous navigation applications.
M.S. in Mechanical and Aerospace Engineering, May 2013
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Title: FABRICATION, CHARACTERIZATION AND RELEASE STUDIES OF LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES
Creator: Zhao, Ziqian
Date: 2015, 2015-07
Description: Nanocomposites exhibit enhanced physical properties including mechanical strength, thermal stability, and gas barrier properties. The...
Show moreNanocomposites exhibit enhanced physical properties including mechanical strength, thermal stability, and gas barrier properties. The development of nanocomposites has led to applications in food industry, mostly in food packaging. The application of nanocomposites in food packaging may extend the shelf life of a food, thus increasing the market value for manufactures. However, there is limited data and research to assess the risk of exposure of nanomaterials to consumers. This project aims at evaluating the factors that can influence the release of nanomateirals in low density polyethylene/clay nanocomposites films. Nanocomposites based on low density polyethylene (LDPE), containing 1, 3, 5 and 7 wt.% of Cloisite 20A and maleic anhydride-grafted polyethylene (MAPE) as a compatibilizer were prepared by melt compounding and characterized in this thesis project. Cloisite 20A is mostly composed of montmorillonite (MMT), which is commonly used as a nanoscale size filler. LDPE/Clay nanocomposite films containing MMT and three mass equivalents of MAPE were successfully extruded into thin films with good optical clarity. The materials were characterized by using transmission electron microscope (TEM), thermogravimetric analysis (TGA), oxygen permeation analysis and a material testing machine. Important properties such as tensile modulus, oxygen transmission rate, thermal resistance and glass transition temperature were measured. Nanocomposite films were immersed in three kinds of food simulants (absolute ethanol, 3% acetic acid and deionized water). Storage time, storage temperature and percent fill of clay were evaluated as the factors that can influence the release of nanomaterials. The content of released of Al, Mg, and Si was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Mg, Al and Si were continuously released from nanocomposite films in duration of 30 days. Fastest releasing speed was found in 3% aqueous acid at 75 °C, and lower temperature can largely decrease the release of nanoparticles. This project is an initial attempt to assess the risks from the use of nanocomposites as food packaging.
M.S. in Food Safety and Technology, July 2015
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Title: BOUNDING ESTIMATION INTEGRITY RISK FOR LINEAR SYSTEMS WITH STRUCTURED STOCHASTIC MODELING UNCERTAINTY
Creator: Langel, Steven Edward
Date: 2014, 2014-05
Description: Safety critical estimation applications require quantification of integrity risk, which is the probability of the state estimate error...
Show moreSafety critical estimation applications require quantification of integrity risk, which is the probability of the state estimate error exceeding predefined bounds of acceptability. Integrity risk can only be evaluated when the state estimate error probability density function is precisely known, necessitating stochastic models that exactly describe measurement noise and disturbance inputs. Uncertainty in these models directly results in inaccurate assessments of integrity risk. This dissertation develops the first implementable methods to upper bound integrity risk when the autocorrelation functions of stochastic inputs reside between upper and lower bounding functions. The first part of this work considers real-valued estimation applications that use the Kalman filter or batch weighted least squares estimator. Explicit relations are developed between the estimate error variance and autocorrelation functions using a new generalized covariance matrix derived in this dissertation. From these expressions, two methods are provided to upper bound integrity risk. The first method enables fast computation of a conservative bound, and the second method produces the minimum upper bound via semi-definite optimization. Mixed real/integer estimation applications utilizing integer bootstrapping are the focus of the second part of this work. The integrity risk bound is formally defined as the global solution to a non-convex optimization problem over a polytope. Determination of the polytopic region is difficult, and two bounding approaches are initially developed for a circumscribing hyper-rectangular feasible region. Using an innovative method to define the polytope together with linear programming, a third method is derived to upper bound integrity risk over the true polytopic feasible region.
PH.D in Mechanical and Aerospace Engineering, May 2014
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Title: PA 508 Student Computer Usage Survey: PA508 Student Survey 2010 Results
Creator: Ahrens, Aric G.
Date: 2010-01-19, 2010-01-19
Description: Included are a survey, and the results in graphic form. The survey was designed to find out how and where the Chinese contingent of Master of...
Show moreIncluded are a survey, and the results in graphic form. The survey was designed to find out how and where the Chinese contingent of Master of Public Administration students used computers. The focus was to determine whether they preferred to use computers on the Downtown Campus, where classes were taught, or on Main Campus, where most of the students lived.
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Title: SURVIVAL OF SALMONELLA ON CHAMOMILE, PEPPERMINT AND GREEN TEA DURING STORAGE RELATED TO TEMPERATURE AND HUMIDITY
Creator: Chen, Zhengzai
Date: 2013-04-24, 2013-05
Description: Botanical/herbal teas may contain antimicrobial compounds that will affect the survival and persistence of the native as well as contaminant...
Show moreBotanical/herbal teas may contain antimicrobial compounds that will affect the survival and persistence of the native as well as contaminant microflora. Although Salmonella are known for their ability to survive in low water activity environments, their survival on dry botanical/herbal teas has not been examined. The purpose of this work is to determine the survival of Salmonella on three types of teas, chamomile peppermint, and green tea under different storage conditions. In addition, the ability of Salmonella to grow in tea brewed with contaminated product was examined. A cocktail of four Salmonella serovars was inoculated onto 1 g samples of chamomile, peppermint, and green tea to give a starting cell population of approximately 10 log cfu/g. The inoculum was allowed to dry prior to storage at 25 °C and 35 °C and at low (<30% RH) and high (> 90% RH) humidity levels. At different time intervals up to 6 months, triplicate samples at each condition were evaluated for surviving Salmonella populations. In addition, samples were used to produce a low-temperature (sun) brewed tea and inoculated. Growth was assessed after 24 hr. Under the four storage conditions tested, survival followed the order 25°C/low RH > 35°C/low RH > 25°C/high RH > 35°C/high RH. Salmonella losses at 25°C/low RH occurred primarily during drying, after which populations showed little declines over 6 months. In contrast Salmonella decreased below detection after 45 days at 35°C and high RH in all teas tested. All teas tested supported the growth of Salmonella after brewing. Storage conditions significantly impact the survival of Salmonella in dried herbal teas. If Salmonella survives after storage, it may also survive and grow after a home brewing process.
M.S. in Food Safety and Technology, May 2013
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Title: IN VITRO STUDIES OF VIRULENCE SUPPRESSION ON P. AERUGINOSA BY PHOSPHATE / POLYPHOSPHATE-LOADED NANOPARTICLES
Creator: Yin, Yushu
Date: 2015, 2015-07
Description: Critically ill patients harbor multi-drug resistant pathogens that can activate their virulence in the response to low nutrient conditions and...
Show moreCritically ill patients harbor multi-drug resistant pathogens that can activate their virulence in the response to low nutrient conditions and host stress derived factors. It was recently shown that the oversupply of inorganic phosphate to bacterial environment can profoundly suppress the virulence of pathogens. Here we hypothesized that phosphateand/ or polyphosphate-loaded nanoparticles can present a tool to deliver and slowly release phosphate in pathogen-rich niche, thereby suppressing bacterial virulence. In this work, a designed study on effect of different phosphate levels (including the phosphate released from hydrogel nanoparticles) on virulence of P. aeruginosa is addressed. In this work, we developed formulations for preparing hexametaphosphate-loaded nanoparticles on the basis of that for phosphate loaded nanoparticles. We utilized inverse miniemulsion polymerization in the synthesis of these nanoparticles. Polyethylene glycol diacrylate (PEGDA, moleculat weight of 575 Da) and N-vinyl pyrrolidone (molecular weight: 111.14 Da ) were chosen to be the initial monomers because the main crosslinker, polyethylene glycol is a kind of biocompatible material that has been approved by the U.S. Food and Drug Administration (FDA). Several parameter could be adjusted among the experiment. We selected the monomer mole fraction of PEGDA-575 as our parameter. After the synthesis, a nanoparticle size distribution between 110 nm and 150 nm was obtained. And these nanoparticles were proved to be able to release phosphate and hexametaphosphate as drug molecules. Although there were release bursts in the test of release kinetics, the crosslink density could be adjusted in following researches. The second part of this study is to test the virulence suppression effect of the nanoparticles in in vitro experiment on a kind of opportunistic pathogen, P. aeruginosa. This kind of gram-negative bacteria is one of the common intestinal microbial communities. We presented the strategy of suppressing virulence while containing rather than killing the bacteria. As a result, polyphosphate loaded nanoparticles showed to be the most effective one among several experiment groups. This result gave this study a promising future in further research in several aspects, such as in vivo test in biomedical and biomedical engineering.
M.S. in Chemical Engineering, July 2015
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Title: Transients on transmission lines and modern protective devices
Creator: Muelleman, Joseph P., Smely, James
Date: 2009, 1920
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/transientsontran00muel
Thesis (B.S.)--Armour Institute of Technology

Title: EBSD CHARACTERIZATION OF LOW TEMPERATURE DEFORMATION MECHANISMS IN MODERN ALLOYS
Creator: Kozmel, Thomas S Ii
Date: 2015, 2015-05
Description: For structural applications, grain re nement has been shown to enhance mechanical properties such as strength, fatigue resistance, and...
Show moreFor structural applications, grain re nement has been shown to enhance mechanical properties such as strength, fatigue resistance, and fracture toughness. Through control of the thermo-mechanical processing parameters, dynamic recrystallization mechanisms were used to produce microstructures consisting of sub-micron grains in 9310 steel, 4140 steel, and Ti-6Al-4V. In both 9310 and 4140 steel, the distribution of carbides throughout the microstructure a ected the ability of the material to dynamically recrystallize and determined the size of the dynamically recrystallized grains. Processing the materials at lower temperatures and higher strain rates resulted in ner dynamically recrystallized grains. Microstructural process models that can be used to estimate the resulting microstructure based on the processing parameters were developed for both 9310 and 4140 steel. Heat treatment studies performed on 9310 steel showed that the sub-micron grain size obtained during deformation could not be retained due to the low equilibrium volume fraction of carbides. Commercially available aluminum alloys were investigated to explain their high strain rate deformation behavior. Alloys such as 2139, 2519, 5083, and 7039 exhibit strain softening after an ultimate strength is reached, followed by a rapid degradation of mechanical properties after a critical strain level has been reached. Microstructural analysis showed that the formation of shear bands typically preceded this rapid degradation in properties. Shear band boundary misorientations increased as a function of equivalent strain in all cases. Precipitation behavior was found to greatly in uence the microstructural response of the alloys. Additionally, precipitation strengthened alloys were found to exhibit similar ow stress behavior, whereas solid solution strengthened alloys exhibited lower ow stresses but higher ductility during dynamic loading. Schmid factor maps demonstrated that shear band formation behavior was in uenced by texturing in these alloys.
Ph.D. in Materials Science and Engineering, May 2015
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Title: PHASE EQUILIBRIA AND THERMODYNAMIC MEASUREMENTS OF SOME HEUSLER COMPOUNDS
Creator: Chen, Song
Date: 2012-08-14, 2012-07
Description: Heusler alloys are compounds based on the original Heusler phase Cu2MnAl which are ternary intermetallics with a particular chemical...
Show moreHeusler alloys are compounds based on the original Heusler phase Cu2MnAl which are ternary intermetallics with a particular chemical stoichiometric formula X2YZ and face-centered cubic structure. Heusler alloys are of interest because of a range of physical phenomena which may occur in them that can be applied in mechanical or electronic devices, including shape memory property and disorder/order phenomenon. In this work, a high temperature drop calorimeters and Setaram calorimeters were used to obtain the enthalpy of formation and heat capacity of compounds in the Mn-based Heusler compounds (X2MnZ). Lattice parameters of these compounds were determined with XRD, and phase equilibria in these alloy system were studied in this work. Phase transformations were studied with DSC and dilatometry. The work is aimed at populating databases for computational thermodynamics, developing an understanding of alloying and clarifying phase equilibria.
M.S. in Material Science and Engineering, July 2012
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Title: THERMODYNAMIC PROPERTIES AND PHASE EQUILIBRIA OF SELECTED HEUSLER COMPOUNDS
Creator: Yin, Ming
Date: 2015, 2015-12
Description: Heusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A...
Show moreHeusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A better understanding of their thermodynamic properties facilitates future design and development. Therefore, standard enthalpies of formation and heat capacities from room temperature to 1500 K of selected Heusler compounds X2YZ (X = Co, Fe, Ni, Pd, Rh, Ru; Y = Co, Cu, Fe, Hf, Mn, Ni, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) and half-Heusler compounds XYSn (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh; Y = Hf, Mn, Ti, Zr) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation were compared with those predicted from ab initio calculations and the extended semiempirical Miedema's model. Trends in standard enthalpy of formation with respect to the periodic classification of elements were discussed. The effect of a fourth element (Co, Cu, Fe, Pd; Ti, V; Al, Ga, In, Si, Ge) on the standard enthalpy of formation of Ni2MnSn was also investigated. Lattice parameters of the compounds with an L21 structure were determined using X-ray powder diffraction analysis. Differential scanning calorimetry was used to determine melting points and phase transformation temperatures. Phase relationships were investigated using scanning electron microscopy with an energy dispersive spectrometer. The isothermal section of the Fe-Sn-Ti ternary system at 873 K was established using equilibrated alloys. Three ternary compounds including the Heusler compound Fe2SnTi were observed. A new ternary compound Fe5Sn9Ti6 was reported and the crystal structure of FeSnTi2 was determined for the first time.
Ph.D. in Mechanical, Materials and Aerospace Engineering
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Title: DEVELOPMENT OF A HIGH ANGULAR RESOLUTION DIFFUSION IMAGING TEMPLATE AND PROBABILISTIC CONNECTIVITY-BASED ATLAS OF THE HUMAN BRAIN
Creator: Varentsova, Anna
Date: 2016, 2016-05
Description: Digital human brain atlases consisting of MRI-based templates and semantic labels delineating different brain regions serve a critical role in...
Show moreDigital human brain atlases consisting of MRI-based templates and semantic labels delineating different brain regions serve a critical role in neuroimaging, mainly facilitating spatial normalization and automated segmentation for the purposes of voxel-wise, region-of-interest, and network analyses. Diffusion MRI templates contain rich information about the microstructure of the brain, however the accuracy of templates constructed based on the diffusion tensor imaging (DTI) model is limited in regions with complex neuronal microarchitecture. High angular resolution diffusion imaging (HARDI) overcomes limitations of the DTI model and is capable of resolving intravoxel heterogeneity. In this work a method to develop artifact-free HARDI template of the human brain from low angular resolution data is presented. Existing white matter (WM) atlases have been generated either based on anatomical landmarks, thus mixing tracts with substantially different roles, or using DTI tractography, which fails in regions with crossing fibers. Connectivity-based atlases developed using HARDI templates and probabilistic tractography have potential to identify functionally distinct subregions of the brain. This work presents connectivity-based atlas of human brain WM created using HARDI template in ICBM-152 space and a set of FreeSurfer grey matter labels.
Ph.D. in Physics, May 2016
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Title: Screech Tones of Supersonic Jets from Bevelled Rectangular Nozzles
Creator: Tam, Ckw, Shen, H., Raman, G.
Date: 1997-07
Publisher: American Inst Aeronaut Astronaut
Description: It is known experimentally that an imperfectly expanded rectangular jet from a thin-lip convergent nozzle emits only a single dominant screech...
Show moreIt is known experimentally that an imperfectly expanded rectangular jet from a thin-lip convergent nozzle emits only a single dominant screech tone. The frequency of the screech tone decreases continuously with an increase in jet Mach number. However, for a supersonic jet issued from a bevelled nozzle or a convergent-divergent nozzle with straight side walls, the shock cell structure and the screech frequency pattern are fairly complicated and have not been predicted before. It is shown that the shock cell structures of these jets can be decomposed into waveguide modes of the jet flow. The screech frequencies are related to the higher-order waveguide modes following the weakest link screech tone theory. The measured screech frequencies are found to compare web with the predicted screech frequency curves.
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Title: EXPERIMENTAL STUDY, TIME-RESOLVED OBSERVATION, AND ANALYSIS OF NANOSECOND LASER ABLATION AND LASER-INDUCED PLASMA
Creator: Zhou, Yun
Date: 2013, 2013-05
Description: For lasers, there exist many current and potential competitive applications in the areas of manufacturing, materials processing, and so on....
Show moreFor lasers, there exist many current and potential competitive applications in the areas of manufacturing, materials processing, and so on. Nanosecond (ns)-pulsed lasers are often seen in these applications. This dissertation presents the experimental study, time-resolved observation and analysis of nanosecond laser ablation and laser-induced plasma due to ablation, and the analysis is based on physics-based numerical models. Specifically, the following topics have been studied: (1). Plasma induced by ablation using long-duration nanosecond laser pulse Plasma is often produced in laser-material interactions, and may play an important role in many laser-based or laser-assisted technologies, such as laser shock peening (LSP), laser micromachining (through the laser ablation process), laser-induced breakdown spectroscopy (LIBS), and laser propulsion, etc. However, despite the previous work in the literature, the study is still limited for the plasma induced by the ablation process using long nanosecond laser pulses (with durations on the order of ~100 ns). In this dissertation, investigations have been performed on this kind of plasma through fast photography (imaging) and emission spectroscopy techniques, and the experimental results have been analyzed using physics-based computational models. Based on the investigations, the following major interesting findings have been obtained under the investigated conditions: (i) Two high radiation intensity regions are observed in the plasma, and one of them disappears soon after laser pulse ends. The research work shows that this phenomenon is related to the vaporization process from the target surface and the confinement effect of the ambient air. (ii) Laser-induced plasma xvii backward growth phenomenon occurs for target ablation using 100-ns laser pulses, but not for that using 200-ns pulses. The investigation shows that the underlying mechanism is the backward growth of the boundary of the high temperature region without actual backward motion of vapor material. (iii) Under the studied conditions, the core region of the plasma (~100 μm above the laser-ablated target) has relatively low temperatures as compared to some other regions of the plasma, which contradicts the common intuition. (2). Semiconductor ablation utilizing infrared (IR) nanosecond laser pulses Semiconductor micromachining through laser ablation may have the advantages of high spatial resolution, high processing efficiency, good flexibility, and no tool wear. However, most of the prior investigations in the literature on ns laser ablation of semiconductors often employ lasers at the ultraviolet (UV) or visible wavelength. The work using IR ns lasers is limited, but IR ns lasers may often have lower cost and require less external energy consumption to produce the same average laser power output. In this dissertation, the ablation of semiconductors using IR ns lasers has been studied through time-resolved observations (fast photography) and the results have been analyzed utilizing physics-based numerical models. The research work shows that the ablation mechanism under the studied conditions is the surface vaporization process during the early stage followed by the subsequent liquid ejection process that occurs at a later time. The research work and analysis shows that the underlying mechanism for the observed liquid ejection should be due to the spatial gradient of the pressure exerted on the target surface, instead of phase explosion. (3). Laser-induced backside ablation (LIBA) of sapphire with IR ns laser pulses xviii LIBA may potentially provide a good solution for high-quality and highefficiency micromachining of wide-band-gap dielectrics (WBGD). However, the prior work on LIBA of sapphire (which is a very important WBGD material) using low-cost IR ns lasers has been rarely reported. This kind of work has been carried out in this dissertation, and the investigation shows that under the studied conditions LIBA can produce very high material removal efficiency and reasonably good quality of machining without obvious chemical contamination coming from the employed backing layer. The ablation rate and damage threshold are measured under different laser parameters, and the research work may provide useful information for the applications of LIBA in practical areas using IR ns lasers that may often have relatively lower cost than UV or visible ns lasers.
PH.D in Mechanical and Aerospace Engineering, May 2013
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Title: The yield of acetic acid as influenced by temperature in wood distillation
Creator: Marx, Walter L.
Date: 2009, 1913
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/yieldofaceticaci00marx
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaf 22

Title: FIELD AND PHOTO-EMISSION IN A SHORT-PULSE, HIGH-CHARGE CESIUM TELLURIDE RF PHOTOINJECTOR
Creator: Wisniewski, Eric E.
Date: 2014, 2014-05
Description: A new high-charge RF gun is now operating at the Argonne Wakefield Accelerator (AWA) facility at Argonne National Laboratory (ANL). The 1.5...
Show moreA new high-charge RF gun is now operating at the Argonne Wakefield Accelerator (AWA) facility at Argonne National Laboratory (ANL). The 1.5 cell 1.3 GHz gun uses a Cesium telluride photocathode driven with a 248 nm laser to provide short-pulse, high charge electron beams for the new 75 MeV drive beamline. The high-gradient RF gun (peak field on the cathode > 80MV/m) is a key piece of the facility upgrade. The large Cs2Te photocathode (diameter > 30 mm) was fabricated in-house. The photo-injector will be used to generate high-charge, short pulse, single bunches (Q > 100 nC) and bunch-trains (Q>1000 nC) for wakefield experiments, typically involving dielectric-loaded accelerating structures. Details of the photocathode fabrication process and the results of associated diagnostic measurements are presented, including QE measurements and work function measurements performed with a Kelvin probe. Field-emitted dark current from the Cs2Te cathode was measured during RF conditioning and characterized. Fowler-Nordheim plots of the data are presented and compared to similar measurements made using a copper cathode in the initial phase of conditioning. The results for cesium telluride exhibited non-linear regions within the Fowler-Nordheim plots similar to previous experimental results for other p-type semiconductors. Results of quantum efficiency (QE) studies are presented with the cathode operating in both single and bunch-train modes. QE uniformity and lifetime studies are presented. During commissioning, the cesium telluride photocathode produced bunch-charge of 100 nC, breaking the previous record. No evidence of bunch-train position-dependence of QE was found when generating four-bunch trains with total charge up to 200 nC.
PH.D in Physics, May 2014
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Title: SAFETY TRAINING IN CONSTRUCTION
Creator: Demirkesen, Sevilay
Date: 2011-11-29, 2011-12
Description: The construction industry is one of the most hazardous industries. Therefore, the ways to reduce the number of risks have been a concern for...
Show moreThe construction industry is one of the most hazardous industries. Therefore, the ways to reduce the number of risks have been a concern for construction companies. Safety training is considered as one of the most efficient ways of improving safety record. Therefore, this study aimed to describe the best safety training methods and the most efficient organization in safety training. The study also aimed to show how to take best safety measures to protect construction workers. In this thesis study, a questionnaire was conducted in order to investigate the achievement of safety learning, challenges in a safety training program and the methods of improving safety record. Thus, the questionnaire was e-mailed to 400 contractors in US. The data collected also indicated the importance of safety training in companies’ success in the industry. Additionally, this study presents recommendations on how companies could improve their safety record.
M.S. in Civil Engineering, December 2011
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