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(121 - 140 of 2,716)
Pages
- Title
- Tests on the gravity cell
- Creator
- Evans, P. W., Linderberg, W. A.
- Date
- 2009, 1912
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/testsongravityce00evan
Thesis (B.S.)--Armour Institute of Technology
- Title
- ECONOMIC BASED CONTROL SYSTEM DESIGN
- Creator
- Omell, Benjamin Peter
- Date
- 2013, 2013-12
- Description
-
EMPC differs from traditional MPC by directly utilizing a profit based function as the objective as opposed to a quadratic function that...
Show moreEMPC differs from traditional MPC by directly utilizing a profit based function as the objective as opposed to a quadratic function that minimizes the distance from a set point that is predetermined. However, implementation of EMPC can result in unexpected and at times pathological closed-loop behavior, including inventory creep, bang-bang actuation and instability. To address these issues, an infinite-horizon version of EMPC is developed and shown to avoid many of the performance issues observed in the finite-horizon version. First, modifications to the EMPC problem will be used for the conceptual development of the Economic Linear Optimal Controller (ELOC), which is a statistically constrained linear feedback controller. Then, pointwise- in-time constraints can be reintroduced using one of two methods; Constrained ELOC or Infinite-Horizon EMPC (IH-EMPC). We also investigate the impact of problem formulation modifications on the ELOC. The first issue is that of disturbance modeling and the second is the impact of controller sample-time. The third topic concerns incorporation of computational delay in the feedback-loop, using both full and partial state information structures. Finally an illustration of the impact of plant-model mismatch is presented. The Constrained ELOC formulation is further modified to allow for market responsive smart grid applications. In particular an Integrated Gasification Combined Cycle (IGCC) process with hydrogen storage will be used to demonstrate the Constrained ELOC for such applications. The ELOC will be used as a vehicle to exploit dispatch capabilities by pursuing directly the objective of maximizing revenue. The idea being that process modifications to enable dispatch capabilities will allow for a time-shift of power production away from periods of low energy value to periods of high value. An in depth discussion is provided on how energy value forecasts are incorporated into the design of the constrained ELOC. Finally, an extension of the ix ELOC to the controller embedded equipment design is provided. The work concludes with a discussion of the computational aspects of solving the ELOC problem. In particular, the impact of reverse-convex constraints inherent to the ELOC problem are discussed along with existing solution methods. The main contribution of this final chapter is a novel application of the Generalized Bender’s Decomposition (GBD) algorithm to the ELOC problem. This new approach is shown to retain global optimality, reduce computational effort (by orders of magnitude) and expand the class of problems one can solve.
PH.D in Chemical Engineering, December 2013
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- Title
- POWER OPTIMIZATION IN DEEP SUBMICRON VLSI CIRCUITS: FROM SYSTEM LEVEL TO CIRCUIT LEVEL
- Creator
- Tong, Qiang
- Date
- 2017, 2017-07
- Description
-
As VLSI technology advances to deep sub-micron regime, power consumption has become a critical concern in VLSI circuits. Therefore, power...
Show moreAs VLSI technology advances to deep sub-micron regime, power consumption has become a critical concern in VLSI circuits. Therefore, power optimization becomes mandatory in VLSI design nowadays. To reduce the power consumption, many techniques have been proposed at various levels of VLSI circuits design: system level, register-transfer level(RTL), and circuit/transistor level. This dissertation starts with a review of system level power optimization techniques. Experiments on a computer architecture simulation system have been conducted to compare the impact of different programming styles at system level on power consumption. The results could be used as an intuitive guidance for programmers with intention for implementing power-aware system. The second topic in this dissertation is a clustering based clock gating technique, targeting power reduction at RT-Level. Clock gating is an effective and popular method to reduce dynamic power in VLSI circuits, it can be applied at both RT-level and gate level. The basic idea of clock gating is to disable the clock of one or more sequential logics (majorly flip-flops) when the input data of the logic cells do not change. In this dissertation, a clustering based clock gating technique is proposed, the technique exploits activity information of each flip-flop, and clusters them into groups according to their activity correlations. As the leakage power has become a major concern in VLSI design, the proposed As the leakage power has become a major concern in VLSI design, the proposed clustering method is extended down to gate level and a clustering based hybrid clock gating and power gating technique is proposed. The technique can reduce both the dynamic power and leakage power in VLSI circuits. As process technology scaling down to deep submicron regime, bulk CMOS technology has encountered many challenges due to short channel effect (SCE), which degrades the reliability and feasibility of MOSFET devices. New technologies such as FinFET and carbon nanotube FET (CNFET) are two promising substitute solutions in the following decade to address SCE issue. Part of this dissertation presents circuit design using these new process technologies for low power VLSI circuits. More specifically, two SRAM cell designs using FinFET and CNFET devices are proposed. The new designs can improve performance while reduce power consumption.
Ph.D. in Electrical Engineering, July 2017
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- Title
- NATURAL AGING EFFECT ON DOUBLE AGED ALUMINUM ALLOY AA7075
- Creator
- Kara, Baris
- Date
- 2012-04-27, 2012-05
- Description
-
The effect of natural aging (NA) on mechanical properties in double aged aluminum alloys, AA7075, was studied by means of hardness tests,...
Show moreThe effect of natural aging (NA) on mechanical properties in double aged aluminum alloys, AA7075, was studied by means of hardness tests, tensile tests and stress corrosion cracking (SCC) tests. Natural aging can strengthen AA7075 alloys after solution heat treatment, and reaching the stable condition can take years for the alloy. Double aging (DA) is very beneficial method in terms of energy savings and productivity because this method provides the peak hardness in a much shorter time compared to single aging, and DA treatment produces hardness, yield stress and tensile stress which are comparable with those produced by SA. In this study, the alloys were naturally aged for different times before double aging treatment, and the relationship between double aging treatment and natural aging treatment was observed. The results show that different natural aging times do not significantly affect the final mechanical properties of double aged alloys. Consequently, the loading time to aging furnace after solution heat treatment does not play an important role in the double aging treatment of AA7075 alloys.
M.S. in Materials Science and Engineering, May 2012
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- Title
- FLEXIBLE COGNITIVE STYLE MODERATES THE RELATIONSHIP BETWEEN RUMINATION AND AFFECT
- Creator
- Smetter, Joseph B.
- Date
- 2014, 2014-12
- Description
-
Prospective and longitudinal studies have demonstrated that rumination has a negative effect on mood and depression outcomes. The present...
Show moreProspective and longitudinal studies have demonstrated that rumination has a negative effect on mood and depression outcomes. The present study examined whether the type of flexible cognitive style needed to reevaluate maladaptive thoughts and interpretations (i.e. cognitive flexibility) acts as a buffer against the negative relationship between rumination and affect. Participants (N = 100) completed anonymous online surveys containing two measures of cognitive flexibility, including the Beck Cognitive Insight Scale (BCIS; Beck et al., 2008) and the Cognitive Flexibility Inventory (CFI; Dennis & Vander Wal, 2010), as well as measures of depressive rumination and trait affect. Multiple regression-based moderation analyses showed that the tendency to be more objective, reflective, and open to feedback moderated the relationship between rumination and positive affect (PA), such that the negative relationship between rumination and PA was attenuated for individuals who were more self-reflective. We discuss the implications of this buffering effect for theories of rumination and research on protective factors, as well as its relevance to psychotherapy. A comparison of the cognitive flexibility questionnaires revealed differences in how flexible reinterpretation is measured and identified selective relationships to positive and negative affect. Based on these findings, we provide recommendations for future research on cognitive styles that promote flexible reinterpretation.
M.S. in Psychology, December 2014
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- Title
- SYSTEM DESIGN AND HARDWARE VERIFICATION OF A S-MFCW RADAR
- Creator
- Nadkarni, Satwik
- Date
- 2014, 2014-05
- Description
-
Low cost imaging radar systems are an emerging field today with very useful applications in automotive, healthcare and entertainment...
Show moreLow cost imaging radar systems are an emerging field today with very useful applications in automotive, healthcare and entertainment industries. The aim is to realize an effective and reliable radar system that has a good resolution and at the same time a low cost and complexity. The S-MFCW radar technique has been shown to achieve comparable resolution with the FMCW technique while at the same time maintaining the advantages of reduced hardware complexity and low power consumption. This makes the S-MFCW technique very useful in low cost and low complexity user end devices. The aim of this thesis is to develop a S-MFCW radar system that is capable of measuring distance of an object as well as its velocity. The radar system was implemented using two different approaches – a modular approach and an integrated approach. Both the implementations were tested and the results were found to be in line with expectations from previous research work.
M.S. in Electrical Engineering, May 2014
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- Title
- THE CORRELATION BETWEEN FATIGUE PROPERTY AND PORE MORPHOLOGY OF POWDER METALLURGY TI6AL4V
- Creator
- Yan, Yingjie
- Date
- 2012-12-12, 2012-12
- Description
-
The microstructure and fatigue properties of sintered Ti-6Al-4V were investi- gated as a function of sintered density and pore morphology. A...
Show moreThe microstructure and fatigue properties of sintered Ti-6Al-4V were investi- gated as a function of sintered density and pore morphology. A quantitative analysis of microstructure was conducted to correlate with tensile and fatigue properties to understand the in uence of sintering density and pore morphology. Low cycle fatigue (LCF) using constant strain control was conducted at room temperature, R=-1 and sine waveform. High cycle fatigue (HCF) using constant stress control was conducted at room temperature, R=0.1 and sine waveform. It was found that there was no signi cant di erence in tensile strength but the fatigue endurance limit was increased by 20% when the sintering density was increased from 95% to 99%. Moreover, fatigue endurance limit was increased when the shape factor increased among three di er- ent sintering conditions(1010 -60min-690MPa, 1130 -90min-410MPa, 1250 -30min- 550MPa). Fracture surface analysis indicated that the fatigue crack initiated from the cluster of pore either at surface or at the sub-surface. The implication of pore morphology and porosity on mechanical behaviour and fatigue fracture of P/M Ti- 6Al-4V were discussed. It was estimated that the shape factor was 0.05 for A-50 and 0.07 for A-100, respectively. A polynomial relationship was found between the fatigue endurance limit and shape factor among three sintering con gurations. It was found that the PM parts with a higher shape factor had a higher fatigue endurance limit.
M.S. in Materials Science and Engineering, December 2012
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- Title
- BIOPHYSICAL AND BIOCHEMICAL STUDY OF NATIVE AND EDITED DYSTROPHIN ROD REGION
- Creator
- Mangat, Khushdeep
- Date
- 2014, 2014-12
- Description
-
Duchenne Muscular Dystrophy (DMD) is a severe X-linked recessive disease affecting 1 in 3500 boys that is characterized by the degeneration of...
Show moreDuchenne Muscular Dystrophy (DMD) is a severe X-linked recessive disease affecting 1 in 3500 boys that is characterized by the degeneration of muscle function and strength. The cause of this disease lies in gene defects that eliminate expression of the protein dystrophin. Becker Muscular Dystrophy, BMD is a milder form of disease that has a later onset and much longer survival (up to the 7th decade of life, compared to median survival of 25 years for DMD patients) because of the presence of low levels of modified dystrophin protein. BMD is very heterogeneous, however, and many cases are nearly as severe as DMD. A major therapy for DMD involves exon skipping, which produces modified forms of dystrophin that are very similar to BMD. However, how these edits impact the function of dystrophin, and how they are linked to the severity of BMD or the BMD-like state produced in DMD exon skip therapy is unknown. We investigated this in two specific cases involving a specific panel of BMD defects linked to a major cause of death, dilated cardiomyopathy (DCM). We also investigated the contribution of various exons to interaction with a signaling partner of dystrophin, neuronal nitric oxide synthetase (nNOS).
Ph.D. in Biological and Chemical Sciences, December 2014
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- Title
- PHYSICS-PRESERVING FINITE DIFFERENCE SCHEMES FOR THE POISSON-NERNST-PLANCK EQUATIONS
- Creator
- Flavell, Allen
- Date
- 2014, 2014-07
- Description
-
The Poisson-Nernst-Planck equations are a system of nonlinear di erential equations that describe ow of charged particles in solution. This...
Show moreThe Poisson-Nernst-Planck equations are a system of nonlinear di erential equations that describe ow of charged particles in solution. This dissertation is about the design of numerical schemes to solve this system which preserves global properties exhibited by the system. There are two major advances presented. The rst is the design of schemes that conserve mass globally when the system is coupled with no- ux boundary conditions. Most notably, a scheme using central di erencing and TR-BDF2 achieves second order accuracy in both space and time, while also conserving global mass is presented. The second is the design of a more general scheme that preserves the time-varying properties of the free energy of the system. One such a scheme uses central di erencing in space and trapezoidal integration in time to achieve second order accuracy in both space and time, while also preserving the energy dynamics, but at the cost of requiring positivity of the solution. There is also a discussion of solution methods: the classic Newton iteration scheme is compared with a modi ed Gummel iteration scheme for the purpose of solving the transient equations. The intended application of this work is the modeling of ion channels, and many of the simulations presented use parameters consistent with models of ion channels.
Ph.D. in Applied Mathematics, July 2014
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- Title
- DEVELOPMENT AND VALIDATION OF A HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR SIMULTANEOUS DETERMINATION OF VITAMINS A AND D IN FLUID MILK PRODUCTS
- Creator
- Li, Wenjing
- Date
- 2013, 2013-12
- Description
-
Measurement of fortification levels for vitamins A and D in fluid milk products is required by the U.S. Food and Drug Administration (FDA)...
Show moreMeasurement of fortification levels for vitamins A and D in fluid milk products is required by the U.S. Food and Drug Administration (FDA) according to Pasteurized Milk Ordinance. In the current study, a high performance liquid chromatographic (HPLC) method was developed for simultaneous determination of retinyl palmitate (vitamin A) and cholecalciferol (vitamin D3) in fortified milk, which will enhance the efficiency of routine monitoring of fortification for processors as well as laboratories. Saponification conditions and extraction solution compositions were studies for best recovery and simplification of the extraction procedures. Saponification conditions studied included temperature (20, 40 and 60℃), time (0.5 to 16 hour) and concentration of KOH (20, 30, 40 and 50%). The variables studied for extraction included solvent compositions (hexane, diethyl ether, ethyl acetate and dichloromethane) and corresponding polarities (0.1, 0.25, 0.5 and 0.75), and number of extractions (once, twice and three times). Freezing and centrifuging steps were also investigated to compare to SPE clean-up, as an alternative method to clean-up before injection. The optimum parameters found were: saponification conditions at 60℃ for 2 hours with 40% (w/v) KOH liquid-liquid extraction with hexane: diethyl ether (80:20, v:v). Vitamins A and D3 were quantitated using an HPLC system with fluorescence detector (FLD) and diode array detector (DAD) respectively within the same injection. Spike recoveries from three different fat levels (skim, 2% and whole) of commercial pasteurized milk samples were in the range of 94 to 110% for both vitamins A and D3 at three spike concentration levels. In addition, at National Institute of Standards and Technology (NIST) Standard Reference Material (SRM 1849a) was used xii for method accuracy evaluation. With eight replicates, the average vitamin A (expressed as retinol equivalents) concentration was 7.52 ± 0.23 μg/g, vitamin D3 concentration was 0.114 ± 0.0062 μg/g, an excellent agreement with the certified value of 7.68 ± 0.23 μg/g for vitamin A and 0.11 ± 0.017 μg/g for vitamin D3. In summary, an HPLC method for simultaneous determination of vitamins A and D3 in fluid milk products has been developed. The method showed high efficiency and accuracy of analysis during a single laboratory validation.
M.S. in Food Safety and Technology, December 2013
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- Title
- OPTIMAL MATERIAL SELECTION MODEL FOR LEED CERTIFICATION USING GENETIC ALGORITHMS
- Creator
- Kim, Taehyoung
- Date
- 2012-12-16, 2012-12
- Description
-
Material selection is an important part of building design because it has great impact on the environment, as buildings during/after...
Show moreMaterial selection is an important part of building design because it has great impact on the environment, as buildings during/after construction are responsible for a large portion of carbon emissions and use many resources and considerable energy. Selecting green materials is an emergent issue in both design firms and construction companies. Green building certification such as LEED systems originated from the desire to improve environmental, economic, financial, and social benefits. The current approach to material selection for sustainability is based only on the designer’s past experiences. An arbitrary approach based on subjective opinions causes unnecessary expense, longer construction duration, and failure to meet desired environmental goals. In order to help decision-makers with the selection of the right materials, this study proposes a model that uses Genetic Algorithms in MATLAB and that optimizes the desired points in LEED Certification within budget constraints. This model can be applied to any project that is pursuing LEED Certification. If the user specifies the desired LEED points, the system recommends the least expensive combination of materials extracted from a database containing detailed information about a large member of materials. The modified model uses multi-objective genetic algorithms to establish trade-off between budget constraints and LEED points. The proposed system is expected to be a useful tool for inexperienced designers and a valuable guideline for designers with extensive experience.
M.S. in Civil Engineering, December 2012
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- Title
- Test of a delco lighting plant
- Creator
- Porges, Edward D., Given, Louis E
- Date
- 2009, 1917
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/testofdelcolight00porg
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaf 88
- Title
- Study of the production of resorcin
- Creator
- Cable, D. E., Prest, J. I.
- Date
- 2009, 1918
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/studyofproductio00cabl
Thesis (B.S.)--Armour Institute of Technology
- Title
- INTEGRATION OF TANGENTIAL FLOW FILTRATION AND IMMUNOMAGNETIC SEPARATION FOR RAPID DETECTION OF ESCHERICHIA COLI 0157:H7 IN PRODUCE WASH WATER
- Creator
- Ren, Yan
- Date
- 2011-12-12, 2011-12
- Description
-
Escherichia coli O157:H7 is one of the most commonly reported pathogens associated with microbial contamination of leafy greens. Since washing...
Show moreEscherichia coli O157:H7 is one of the most commonly reported pathogens associated with microbial contamination of leafy greens. Since washing is a major postharvest processing step, microbial testing of spent wash water has been suggested as a good marker to determine the contamination status of the products. In this study, the efficiency of four commercial rapid methods (BAX®, IQ-Check, Reveal® and mini-VIDAS®) for detection of E.coli O157:H7 in lettuce wash water was evaluated in comparison with the FDA BAM method. The improvement of the detection sensitivity of these tests by immunomagnetic separation (IMS) technology and sample pre-concentration by Tangential Flow Filtration (TFF) was determined. Twenty-five ml of lab prepared lettuce wash water samples were spiked with 0, 1, 10, 100 CFU of E.coli O157:H7, and subjected to enrichment protocols recommended by each of the methods. The presence of E.coli O157:H7 in the enriched samples were then assayed by the test kits, either directly or after IMS (IMS-Pathatrix ™ or IMS-Dynabeads™) treatments. All four test kits and BAM were able to detect E.coli O157:H7 at levels as low as 1 CFU/25ml of wash water. IMS treatments did not lead to further improvement in detection sensitivity. Experiments were also performed to determine the feasibility of incorporating IMS and sample pre-concentration to achieve culture-free detection. Fifty ml of wash water samples were inoculated with E.coli O157:H7 at levels of 0 to 107 CFU and analyzed by the test kits either directly or after IMS-Pathatrix™ treatment. Additionally, 10 L of wash water either prepared in the lab or collected from a commercial fresh-cut processing facility were inoculated with 0 – 106 CFU of the pathogen and subjected to TFF concentration prior to IMS or test kit analyses. IQ-Check showed the highest sensitivity with a detection limit as low as 103 CFU/50ml, and, with IMS, achieved a sensitivity of 100 CFU/50ml. Combining TFF concentration and IMS, 10 L of lab prepared wash water can be tested with IQ-Check and achieve a detection limit of approx. 100 CFU/10 L within 6 hours. For 10L of industry spent wash water, IQ-check also showed the highest sensitivity but the results lacked consistency and required additional evaluations.
M.S. in Food Safety and Technology, December 2011
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- Title
- RECONFIGURABLE ANALOG FRONT-END SYSTEM FOR ULTRASONIC IMAGING APPLICATIONS
- Creator
- Vasudevan, Vidya
- Date
- 2014, 2014-12
- Description
-
Ultrasonic systems, applied in the field of Medical Imaging and Non-Destructive Testing, have evolved from the trolley-based units to more...
Show moreUltrasonic systems, applied in the field of Medical Imaging and Non-Destructive Testing, have evolved from the trolley-based units to more portable, hand-held devices. These systems are built to suit a specific application or aim at specific target material. In order to make these systems portable and adaptable to the testing environment, a flexible and programmable hardware is built. A fully configurable Analog Front-End (AFE) is presented, which possesses the capability for dynamic re-configuration by using ARM processing core for real-time control, data acquisition and signal analysis in a Linux environment. This system supports up to 8 ultrasonic sensors. The flexibility built into the AFE allows for various beamforming and signal conditioning requirements. This reconfigurable system enables ultrasonic researchers to efficiently prototype different experiments and to incorporate high performance ultrasonic signal and image processing algorithms. This system provides real-time signal processing for nondestructive evaluation (NDE) and imaging applications using ultrasonic sensors ranging from 60 KHz to 15 MHz operating frequencies. A dynamically reconfigurable sensor interface is presented for ultrasonic pulse-echo measurements targeting flaw detection and parametric echo classification applications. For real-time implementation, a SoC-based system is developed on an ARM platform. For a working system, a BCM2835 SoC on a Raspberry Pi hardware system is explored with a further upgrade to Xilinx Zynq 7020 SoC in order to achieve a higher throughput.
M.S. in Electrical Engineering, December 2014
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- Title
- HYBRID TO SOCIAL CONDENSER: COMPETING APPROACHES TO MIXED-USE DEVELOPMENT
- Creator
- Zagow, Maged
- Date
- 2016, 2016-12
- Description
-
In the last two decades, mixed use has taken center stage in urban planning development in the United States. The research frequently cites...
Show moreIn the last two decades, mixed use has taken center stage in urban planning development in the United States. The research frequently cites this development as a model that can address a variety of socioeconomic problems. Also, it has enjoyed a recent surge in popularity in redeveloping cities by providing more affordable housing opportunities, ensuring safety, reducing auto-dependency, and for providing a sense of place and community. However, its affordability, physical design, and outcomes are highly variable. This study is particularly interested in whether and how mixed use affects the socioeconomics configuration of the built environment. This study uses multilevel data from the county level to the zip code level that represents all US neighborhoods. I use different implementation methods of mixed-use development and different cultural and historical backgrounds to examine the data. The study adopts six mixed-use models that present different methodological interactions between socioeconomic spatial metrics and urban forms. These models represent the realistic constraints of urban geometry and of the socioeconomic structure that comprises the charateristics of race, income, accessibility, safety, adjacency, accessibility, environment, and density. This study finds that the built environment produces a rich landscape of information that appears to guide the opportunities for facilities. The analysis shows that mixed-use development may have certain effects on the number of facilities, housing, income, diversity, crime rate, employment, health, and environment. The analysis of this research works in two dimensions. First, urban models (Hybrid and Social Condenser in general and under two categories Metropolis and Neighborhood Community). The second dimension is the urban characteristics (zoning programming, land use mix, streets fabric), socioeconomics variables (Population density, occupied housing, median age, diversity of race, income, and employment rates), and location variation (states, and cities). The results confirm that mixing the facilities in hybrid communities create more jobs opportunities but limit the affordability of housing, social cohesion and the race diversity. But in Social Condenser models, there are more race diversity safety and healthy environment. These results reflect complexity demands more than mixed-use developments, beyond Jane Jacobs' requirements, and beyond the designation of selected mixed-use zones. This study contributes to the study of how mixed-use development models shift because of various social and economic conditions. The findings from this study can inform architects, investors, policymakers, economists, and planners about factors that sustain mixed-use neighborhoods in the United States and beyond. Urban designers will be able to inform how the seemingly necessary act of laying out mixed-use development can affect the socioeconomic structure of a city. Thus, this study is a useful source for more accurate planning ideas than generic abstract theories or slogans.
Ph.D. in Architecture, December 2016
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- Title
- STUDIES ON SYNTHETIC APPLICATIONS OF STEREOSELECTIVE AND REGIOSELECTIVE RING OPENING REACTIONS OF AZIRIDINIUM IONS
- Creator
- Chen, Yunwei
- Date
- 2014, 2014-12
- Description
-
Aziridinium ions are valuable reactive intermediates in organic synthesis. Regioselective and stereoselective ring opening reactions of...
Show moreAziridinium ions are valuable reactive intermediates in organic synthesis. Regioselective and stereoselective ring opening reactions of aziridinium ions can provide various useful building blocks including optically active vincinal amines, amino alcohols and amino esters. Aziridinium ions are also involved in the biological process of anti-cancer agents. However, aziridinium ions are under-utilized in organic synthesis. In this thesis, we utilize stereoselective and regioselective ring opening reactions of aziridinium ions for synthesis of enantiomerically enriched compounds. Ring opening reactions of aziridinium ions were utilized in intramolecular Friedel-Crafts (FC) reactions for stereoselective and regioselective synthesis of 4-substituted tetrahydroisoquinoline. A series of β-haloamine were prepared as precuresors of aziridinium ions. The reaction conditions for ring opening of aziridinium ions for the FC reactions including temperature, catalysts, and solvents were optimized. Further, the reaction mechanism was studied to prove that the aziridinium ions were formed as the key intermediates during the intramolecular FC reaction. Intermolecular nucleophilic ring opening reaction of aziridinium ions was studied as a convenient method of carbon-carbon formation. Regioselective and stereoselective nucleophilic substitution reactions of aziridinium ions with indole analogues were carried out for the synthesis of optically active tryptamine analogues. The reactions proceeded smoothly to provide the tryptamine analogues in high yield in the presence of halo-sequestering agents, while the reaction provided the tryptamine products in significantly low yield in the absence of halo-sequestering agents. Ring opening reactions of aziridinium ions with malonic esters and Grignard reagents were carried out for the respective synthesis of optically active tryptamine analogues, γ-aminobuyric acid (GABA), and α-amine derivatives. The regiospecific ring opening reactions of aziridinium ions was directly applied for the synthesis of bifunctional ligands which have a potential use in targeted therapy and imaging of cancers. The novel bifunctional chelates with a shorter alkyl spacer C-NETA and 2E-C-NETA as well as the chelates with a longer alkyl spacer 5p-C-NETA were prepared. 5p-C-NETA was conjugated to a cyclic peptide c(RGDyK) as a targeting moiety for use in targeted radiation therapy. In addition, 2E-C-NETA was conjugated to a fluorescent dye Cy5.5 for theranostic applications. The experimental results indicated that the new bifunctional ligands have promising applications in the biomedical field. In summary, stereoselective and regioselective ring opening reactions of aziridinium ions have been successfully applied for the synthesis of optically active compounds such as 4-substituted tetrahydroisoquinolines, tryptamines, γ-aminobuyric acid, α-amine derivatives and the bifunctional chelators. We demonstrated that ring opening of versatile aziridinium intermediates is a strightforward and convenient method for the synthesis of various optically active compounds.
Ph.D. in Chemistry, December 2014
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- Title
- Test of slender wooden struts for aeroplanes
- Creator
- Smith, M. A,, Kellener, W. A., Stevens, W. A.
- Date
- 2009, 1910
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/testofslenderwoo00smit
Thesis (B.S.)--Armour Institute of Technology
- Title
- A CONCEPTUAL SOLAR CHIMNEY PLANT AND FLORAL FARM USING ETFE AND BAMBOO
- Creator
- De Vita, Niels
- Date
- 2012-11-20, 2012-12
- Description
-
Motivated by a desire to create an architectural response to the environmental and social challenges of today, the following thesis project...
Show moreMotivated by a desire to create an architectural response to the environmental and social challenges of today, the following thesis project attempts to offer new paths for the future development of the solar chimney energy plant concept originally developed by the German engineer Jӧrg Schlaich in the early 1980s. The starting point of this thesis was to analyze the solar chimney prototype completed in the Manzanares desert in 1982 in order to understand the parameters guiding the design. The analysis allowed me to better understand the potential of the concept and to recognize the opportunity that existed to push the technological boundaries to craft a new design that reflects the current socio-political, economical and environmental context we live in. In the following pages, I attempt to demonstrate that the concept could be made even more appealing through the use of technology and locally available resources. By doing this, I seek to reinvigorate the idea, opening paths for a new conversation about the potential of the project as a social agent for progress. Throughout this thesis, I remain respectful and aware of the accomplishments of the pioneers before me, simply taking cues from their work to suggest new alternatives and solutions to a problem that has been made even more pressing due to the world’s energy crisis and economic uncertainty.
M.S. in Architecture, December 2012
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- Title
- THE CHANGE OF KURTOSIS IN IMPORTANCE SAMPLING FOR MONTE CARLO
- Creator
- Zhang, Xiaodong
- Date
- 2013, 2013-12
- Description
-
The Mont e Carlo (II IC) Method is commonly used to approximat e mult ivariat e integrals, which can be interpreted as means of random variab...
Show moreThe Mont e Carlo (II IC) Method is commonly used to approximat e mult ivariat e integrals, which can be interpreted as means of random variab les. The IIIC method uses th e sample mean to estimate the tr ue mean. In this thesis, we focus on minimizing th e sample size in MC simulat ion needed to sat isfy the specified error tolerance. Based on t he algorithm proposed by [5], we explain that t he cost of reliable IIIe est imat ion depends not only on variance but also on kurtosis. T herefore, when we try to improve th e efficiency of MC simulation by reducing variance, such as with Importance Sampling (IS), we need also look into the change of kurtosis. We analyze the change of cost in terms of the change of kur tosis and the change of variance. For a special case of IS we explore how to find th e optimal density in order to reduce variance.
M.S. in Applied Mathematics, December 2013
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