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Burcham, Megan Noel. « Multiscale structure-property relationships of ultra-high performance concrete ». Thesis, Mississippi State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10141618.
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The structure-property relationships of Ultra-High Performance Concrete (UHPC) were quantified using imaging techniques to characterize the multiscale hierarchical heterogeneities and the mechanical properties. Through image analysis the average size, percent area, nearest neighbor distance, and relative number density of each inclusion type was determined and then used to create Representative Volume Element (RVE) cubes for use in Finite Element (FE) analysis. Three different size scale RVEs at the mesoscale were found to best represent the material: the largest length scale (35 mm side length) included steel fibers, the middle length scale (0.54 mm side length) included large voids and silica sand grains, and the smallest length scale (0.04 mm side length) included small voids and unhydrated cement grains. By using three length scales of mesoscale FE modeling, the bridge of information to the macroscale cementitious material model is more physically based.
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Hu, Jiazhi. « UNDERSTANDING THE STRUCTURE-PROPERTY-PERFORMANCE RELATIONSHIP OF SILICON NEGATIVE ELECTRODES ». UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/109.
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Rechargeable lithium ion batteries (LIBs) have long been used to power not only portable devices, e.g., mobile phones and laptops, but also large scale systems, e.g., electrical grid and electric vehicles. To meet the ever increasing demand for renewable energy storage, tremendous efforts have been devoted to improving the energy/power density of LIBs. Known for its high theoretical capacity (4200 mAh/g), silicon has been considered as one of the most promising negative electrode materials for high-energy-density LIBs. However, diffusion-induced stresses can cause fracture and, consequently, rapid degradation in the electrochemical performance of Si-based negative electrodes. To mitigate the detrimental effects of the large volume change, several strategies have been proposed. This dissertation focuses on two promising approaches to make high performance and durable Si electrodes for high capacity LIBs.
First, the effect of polymeric binders on the performance of Si-based electrodes is investigated. By studying two types of polymeric binders, polyvinylidene fluoride (PVDF) and sodium alginate (SA) using peel tests, SEM, XPS, and FTIR, I show that the high cohesive strength at the binder-silicon interface is responsible for the superior cell performance of the Si electrodes with SA as a binder. Hydrogen bonds formed between SA and Si is the main reason for the high cohesive strength since neither PVDF nor SA bonds covalently with Si.
Second, the fabrication of high performance Si/polyacrylonitrile (PAN) composite electrode via oxidative pyrolysis is investigated. We show that high performance Si/polyacrylonitrile (PAN) composite negative electrodes can be fabricated by a robust heat treatment in air at a temperature between 250 and 400oC. Using Raman, SEM, XPS, TEM, TGA, and nanoindention, we established that oxidation, dehydration, aromatization, and intermolecular crosslinking take place in PAN during the heat treatment, resulting in a stable cyclized structure which functions as both a binder and a conductive agent in the Si/PAN composite electrodes. With a Si mass loading of 1 mg/cm2, a discharge capacity of ~1600 mAh/g at the 100th cycle is observed in the 400oC treated Si/PAN composite electrode when cycled at a rate of C/3.
These studies on the structure-property-performance relations of Si based negative electrode may benefit the LIB community by providing (1) a guide for the design and optimization of binder materials for Si electrodes and (2) a facile method of synthesizing Si-based composite negative electrodes that can potentially be applied to other Si/polymer systems for further increasing the power/energy density and lower the cost of LIBs for electric vehicle applications and beyond.
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Park, Conrad. « Mechanical Performance and Structure-Property Relations in6061B Aluminum Metal Matrix Composites ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1547842396716777.
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Zhang, Ronghui. « Ownership, property rights structure and economic performance in developed and transitional countries ». Berlin Logos-Verl, 2008. http://d-nb.info/988919591/04.
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Waletzko, Ryan Scott. « Determining soft segment structure-property effects in the enhancement of segmented polyurethane performance ». Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46671.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.Includes bibliographical references.
Liquid Crystalline Elastomer (LCE)-inspired segmented polyurethane elastomers possessing widely different extents of ordering were created to mimic the hierarchical structure of the continuous matrix and superior mechanical performance of spider silk fibers. The silk's remarkable toughness originates from a fiber morphology that possesses [beta]-pleated crystalline sheets within an amorphous matrix. In the polyurethane materials, various extents of poly(ethylene oxide) (PEO) soft segment ordering were implemented within continuous soft domains that were connected by hexamethylene diisocyanate-butanediol (HDI-BDO) hard segments. Soft segment crystallinity studies revealed the need to optimize the extent of continuous soft domain ordering. Highly crystalline PEO soft segments, while they display good microphase segregation properties, sacrifice extensibility due to their high melting transition temperature. Moderately crystalline PEO soft segments, meanwhile, possess less defined phase segregation but enhanced mechanical properties from their reversible dispersed crystalline soft segment domains. Non-crystalline Pluronic copolymer systems had good mechanical properties that resulted from both a strong hard segment incompatibility and a highly mobile soft segment matrix. Hydrogen-bonded hard domain shearing during in-situ tensile deformation yields oriented hard blocks that align at a preferred tilt angle of ±60° from the strain direction. Extensive alignment and orientation of the moderately-ordered PEO soft segments occurred during deformation, which was consistent with its observed mechanical behavior. Pluronic-containing segmented polyurethanes formed an ordered mesophase in the continuous soft matrix during deformation. A series of cyclic, aliphatic polyurethanes with dicyclohexyl methane diisocyanate (HMDI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments was synthesized to study compositional effects on the extent of soft segment mixing, and how these effects translated to both mechanical and barrier performance. Shorter soft segment chain systems displayed a greater hard segment compatibility, which resulted in materials that were both more rigid mechanically and provided better barrier characteristics.
(cont.) Longer soft segments in the continuous polymer matrix displayed a more phase segregated structure, which enhanced their mechanical properties but sacrificed barrier effectiveness. Incorporation of dimethyl propane diol (DMPD), a branched chain extender, created a completely amorphous polyurethane matrix. Polyurethane/Laponite nanocomposites were also created using particles that were capable of preferentially associating with hard or soft segments. HMDI-BDO-PTMO polyurethane/Laponite nanocomposites demonstrated drastically reduced mechanical performance (~13-fold decrease in toughness and ~10-fold decrease in extensibility). The deteriorated mechanical performance was attributed to the formation of an interconnected hard segment continuous morphology that significantly reduced matrix extensibility. HMDI-DMPDPTMO polyurethane/Laponite composites, on the other hand, only experienced modest reductions in extensibility (-70% of total initial extensibility) while maintaining toughess and increasing initial modulus 10-fold. Mechanical behavior resulted from well-dispersed Laponite clay platelets that reinforced the amorphous polymer matrix while imposing modest chain segmental mobility restrictions.
by Ryan Scott Waletzko.
Ph.D.
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Nikkhah, Hamdam. « Enhancing the Performance of Si Photonics : Structure-Property Relations and Engineered Dispersion Relations ». Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37144.
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The widespread adoption of photonic circuits requires the economics of volume manufacturing offered by integration technology. A Complementary Metal-Oxide Semiconductor compatible silicon material platform is particularly attractive because it leverages the huge investment that has been made in silicon electronics and its high index contrast enables tight confinement of light which decreases component footprint and energy consumption. Nevertheless, there remain challenges to the development of photonic integrated circuits. Although the density of integration is advancing steady and the integration of the principal components – waveguides, optical sources and amplifiers, modulators, and photodetectors – have all been demonstrated, the integration density is low and the device library far from complete. The integration density is low primarily because of the difficulty of confining light in structures small compared to the wavelength which measured in micrometers. The device library is incomplete because of the immaturity of hybridisation on silicon of other materials required by active devices such as III-V semiconductor alloys and ferroelectric oxides and the difficulty of controlling the coupling of light between disparate material platforms. Metamaterials are nanocomposite materials which have optical properties not readily found in Nature that are defined as much by their geometry as their constituent materials. This offers the prospect of the engineering of materials to achieve integrated components with enhanced functionality. Metamaterials are a class of photonic crystals includes subwavelength grating waveguides, which have already provided breakthroughs in component performance yet require a simpler fabrication process compatible with current minimum feature size limitations.
The research reported in this PhD thesis advances our understanding of the structure-property relations of key planar light circuit components and the metamaterial engineering of these properties. The analysis and simulation of components featuring structures that are only just subwavelength is complicated and consumes large computer resources especially when a three dimensional analysis of components structured over a scale larger than the wavelength is desired. This obstructs the iterative design-simulate cycle. An abstraction is required that summarises the properties of the metamaterial pertinent to the larger scale while neglecting the microscopic detail. That abstraction is known as homogenisation. It is possible to extend homogenisation from the long-wavelength limit up to the Bragg resonance (band edge). It is found that a metamaterial waveguide is accurately modeled as a continuous medium waveguide provided proper account is taken of the emergent properties of the homogenised metamaterial. A homogenised subwavelength grating waveguide structure behaves as a strongly anisotropic and spatially dispersive material with a c-axis normal to the layers of a one dimensional multi-layer structure (Kronig-Penney) or along the axis of uniformity for a two dimensional photonic crystal in three dimensional structure. Issues with boundary effects in the near Bragg resonance subwavelength are avoided either by ensuring the averaging is over an extensive path parallel to boundary or the sharp boundary is removed by graded structures. A procedure is described that enables the local homogenised index of a graded structure to be determined. These finding are confirmed by simulations and experiments on test circuits composed of Mach-Zehnder interferometers and individual components composed of regular nanostructured waveguide segments with different lengths and widths; and graded adiabatic waveguide tapers. The test chip included Lüneburg micro-lenses, which have application to Fourier optics on a chip. The measured loss of each lens is 0.72 dB.
Photonic integrated circuits featuring a network of waveguides, modulators and couplers are important to applications in RF photonics, optical communications and quantum optics. Modal phase error is one of the significant limitations to the scaling of multimode interference coupler port dimension. Multimode interference couplers rely on the Talbot effect and offer the best in-class performance. Anisotropy helps reduce the Talbot length but temporal and spatial dispersion is necessary to control the modal phase error and wavelength dependence of the Talbot length. The Talbot effect in a Kronig-Penny metamaterial is analysed. It is shown that the metamaterial may be engineered to provide a close approximation to the parabolic dispersion relation required by the Talbot effect for perfect imaging. These findings are then applied to the multimode region and access waveguide tapers of a multi-slotted waveguide multimode interference coupler with slots either in the transverse direction or longitudinal direction. A novel polarisation beam splitter exploiting the anisotropy provided by a longitudinally slotted structure is demonstrated by simulation.
The thesis describes the design, verification by simulation and layout of a photonic integrated circuit containing metamaterial waveguide test structures. The test and measurement of the fabricated chip and the analysis of the data is described in detail. The experimental results show good agreement with the theory, with the expected errors due to fabrication process limitations. From the Scanning Electron Microscope images and the measurements, it is clear that at the boundary of the minimum feature size limit, the error increases but still the devices can function.
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Lee, Yong-Joon. « Structure-property behavior of novel high performance thermoplastic and thermoset structural adhesives and composite matrix resins ». Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-162715/.
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Morrell, Guy D. « Portfolio construction in the UK property market : an investigation of the relative importance of fund structure and stock selection in explaining performance ». Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250718.
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Selli, Daniele. « Structure Property and Prediction of Novel Materials using Advanced Molecular Dynamics Techniques : Novel Carbons, Germaniums and High-Performance Thermoelectrics ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-150244.
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By means of advanced molecular dynamic techniques, we predict the stability of novel materials based on carbon, germanium and PbSe. This topological solutions have been studied and characterised at a DFT/DFTB level of theory and interesting optical, mechanical, electronic and heat transport properties have been pointed out.
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Gardner, Slade Havelock II. « An Investigation of the Structure-Property Relationships for High Performance Thermoplastic Matrix, Carbon Fiber Composites with a Tailored Polyimide Interphase ». Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30757.
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The aqueous suspension prepregging technique was used to fabricate PEEK and PPS matrix composites with polyimide interphases of tailored properties. The structure-property relationships of Ultem-type polyimide and BisP-BTDA polyimide which were made from various water soluble polyamic acid salts were studied. The molecular weight of the polyimides was shown to be dependant upon the selection of the base used for making the polyamic acid salt. The development of an Ultem-type polyimide with controlled molecular weight and properties similar to commercial Ultem 1000 was accomplished with the Ultem-type TPA+ polyamic acid salt. Both the Ultem-type polyimides and the BisP-BTDA polyimides derived from the NH4+ salt and the TMA+ salt were shown to crosslink at elevated temperatures.
Blends of Ultem-type polyimide with PEEK and BisP-BTDA polyimide with PEEK were prepared to study the structure-property relationships of model composite matrices. Since both polyimides are miscible with PEEK, interdiffusion of the polyimides with PEEK is expected, however, the interdiffusion behavior is complicated by the crosslinking mechanism of the polyimides.
Ultem-type polyimide interphase, PEEK matrix composites and BisP-BTDA polyimide interphase, PEEK matrix composites were fabricated using the aqueous suspension prepregging technique and evaluated to determine the effects of the interphase properties on the bulk composite performance and durability. Three different Ultem-type polyimides from the NH4+, TMA+ and TPA+ polyamic acid salts were used and two different BisP-BTDA polyimides from the NH4+ and TMA+ polyamic acid salts were used. The transverse flexure strength was used to qualitatively rank the composites by level of interfacial shear strength. The longitudinal tensile strength of the composites was shown to vary with relative interfacial shear strength. The trend of these data qualitatively support the existence of a maximum longitudinal tensile strength at an optimum interfacial shear strength. Notched fatigue testing of the Ultem-type polyimide interphase, PEEK matrix composites showed that the initial split growth rate increased with decreasing relative interfacial shear strength.
Ultem-type polyimide interphase, PPS matrix composites were fabricated using the aqueous suspension prepregging technique and evaluated to determine the effects of the interphase properties on the bulk composite performance. Three different Ultem-type polyimides from the NH4+, TMA+ and TPA+ polyamic acid salts were used. The transverse flexure strength was used to qualitatively rank the composites by level of interfacial shear strength. The longitudinal tensile strength of the composites was shown to vary with relative interfacial shear strength. The trend of these data qualitatively support the existence of a maximum longitudinal tensile strength at an optimum interfacial shear strength.Ph. D.
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Ojala, Antti [Verfasser], et Frank [Akademischer Betreuer] Würthner. « Merocyanine Dyes as Donor Materials in Vacuum-Deposited Organic Solar Cells : Insights into Structure-Property-Performance Relationships / Antti Ojala. Betreuer : Frank Würthner ». Würzburg : Universitätsbibliothek der Universität Würzburg, 2013. http://d-nb.info/1033751901/34.
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Selli, Daniele [Verfasser], et Gotthard [Akademischer Betreuer] Seifert. « Structure Property and Prediction of Novel Materials using Advanced Molecular Dynamics Techniques : Novel Carbons, Germaniums and High-Performance Thermoelectrics / Daniele Selli. Gutachter : Gotthard Seifert ». Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://d-nb.info/1068447990/34.
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Jovic, Kristina Julia. « New pathways to polymethacrylimide (PMI) foams ». Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/203746/1/Kristina_Jovic_Thesis.pdf.
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High-performance polymer foams such as polymethacrylimides are used to alleviate greenhouse gas emissions by decreasing the overall weight of vehicles. While these non-toxic, lightweight polymethacrylimide foams are time-proven products, their current production process faces several challenges, including toxic and expensive starting materials, insufficient knowledge into their formation mechanism as well as the requirement of high processing temperatures. The current PhD thesis addresses these problems by extending the base of suitable starting materials, developing advanced synthetic routes and establishing an in-depth understanding of the imidization mechanism to tune the thermal and mechanical properties of these versatile materials.
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Liu, Jia. « STRUCTURE PORPERTY RELATIONSHIPS OF HIGH PERFORMANCE POLYBENZOXAZINES ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1407514371.
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Gong, Yun. « Structure-property relationships of dyes as applied to dye-sensitized solar cells ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275007.
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This work investigates the correlation of structural and photovoltaic properties of dyes used in dye-sensitized solar cells. Experimental methods, including ultraviolet-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy are employed to study optical and electrochemical properties of dye molecules. Computational methods, including density functional theory and time-dependent density functional theory, are used to validate and predict the optical and electronic properties of dye molecules, in their isolated state and once embedded into a working electrode device environment that comprises a dye...TiO2 interface. The results chapters begin with the presentation of a series of quinodimethene dyes that are experimentally validated for their photovoltaic application, and associated computational studies reveal that an inner structural factor - a phenyl ring rotation occurring during the optical excitation process - leads to the competitive photovoltaic device performance of these dyes. Carbazole-based dyes are then systematically studied by computation, especially considering charge transfer paths and binding modes of these dyes on a titania surface. The theoretical models for the basic building block of this chemical family of dyes, known as MK-44, successfully support and explain structural discoveries from X-ray diffraction and reflectometry that impact of their function. A benzothiadiazole-based dye, RK-1, is then systematically studied by both experimental and computational methods, and the results show that the π-bridge composed of thiophene, benzothiadiazole and benzene rings leads to excellent charge separation; and the rotation of these rings during the optical excitation process may well be consistent with the fluorescence spectrum. Finally, the well-known ruthenium-based dyes are theoretically studied to determine the properties of different ligands connected to the metal core of the complex. Conformations with different NCS ligands are calculated in terms of energy and explain well the corresponding results from X-ray diffraction. Acid-base properties of carboxyl groups connected to pyridine ligands in N3 and N749 are theoretically calculated based on thermodynamics and density functional theory. Implicit and explicit models are both adopted to predict these acid dissociative constant values, which are generally in a good agreement with the reported experimental data. The thesis concludes with conclusions and a future outlook.
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Burgos, Suarez Gabriel Dario. « The Impact of Ownership Structure on the Financial Performance of Airlines in the International Context ». Walsh University Honors Theses / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=walshhonors1411569757.
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Leindahl, Johan, et Victor Dahlén. « Kapitalstrukturens inverkan på företags lönsamhet och värde : En empirisk studie över svenska börsnoterade fastighetsbolag ». Thesis, Södertörns högskola, Institutionen för samhällsvetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-24117.
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How capital structure influences corporate performance and value has been in the interest of researchers and scholars for more than half a century, but an answer is yet to be found. The main objective of the present paper is to contribute with data for this cause and hopefully help to clarify this mystery. The method that was used was by analyzing the impact of debt on profitability and market valuation through linear regression. The study examined 17 Swedish property companies listed on Nasdaq OMX Large Mid and Small Cap over a 6 year period (2007-2012). The authors found a slightly negative relationship between debt-to-equity and profitability measured by return on equity (ROE) as well as by return on assets (ROA). However, significance was only found in terms of return on assets. The authors found no relationship between debt-to-equity and market valuation measured by price-to-earnings (P/E) nor price-to-book (P/B).
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Divoux, Gilles Michel Marc. « Properties and Performance of Polymeric Materials Used in Fuel Cell Applications ». Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26374.
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Over the past three decades, the steady decrease in fossil energy resources, combined with a sustained increase in the demand for clean energy, has led the scientific community to develop new ways to produce energy. As is well known, one of the main challenges to overcome with fossil fuel-based energy sources is the reduction or even elimination of pollutant gases in the atmosphere. Although some advances have helped to slow the emission of greenhouse gases into the atmosphere (e.g., electric cars and more fuel-efficient gas-burning automobiles), most experts agree that it is not enough.
Proton Exchange Membrane (PEM) fuel cells have been widely recognized as a potentially viable alternative for portable and stationary power generation, as well as for transportation. However, the widespread commercialization Proton Exchange Membrane Fuel Cells (PEMFCs) involves a thorough understanding of complex scientific and technological issues. This study investigated the various structure-property relationships and materials durability parameters associated with PEMFC development.
First, the correlation between perfluorinated ionomer membranes and processing/performance issues in fuel cell systems was investigated. As confirmed by small-angle X-ray scattering data, impedance analysis, and dynamic mechanical analysis, solution processing with mixed organic-inorganic counterions was found to be effective in producing highly arranged perfluorinated sulfonic acid ionomer (PFSI) membranes with more favorable organization of the ionic domain. Moreover, thermal annealing was shown to enhance the proton
mobility, thereby facilitating reorganization of the polymer backbone and the hydrophilic region for improved crystallinity and proton transport properties. This research also confirmed an increase in water uptake in the solution-processed membranes under investigation, which correlated to an increase in proton conductivity. Thus, annealing and solution-processing techniques were shown to be viable ways for controlling morphology and modulating the properties/performance of PFSI membranes.
Second, this study investigated the role of the morphology on water and proton transport in perfluorinated ionomers. When annealed at high temperatures, a significant decrease in water uptake and an increase in crystallinity were observed, both of which are detrimental to fuel cell performance. Additionally, controlling the drying process was found to be crucial for optimizing the properties and performance of these membranes, since drying at temperatures close or above the α-relaxation temperature causes a major reorganization within the ionic domains.
Third, although many investigations have looked at key PEMFC components, (e.g., the membrane, the catalyst, and the bipolar plates), there have been few studies of more â minorâ componentsâ namely, the performance and durability of seals, sealants, and adhesives, which are also exposed to harsh environmental conditions. When seals degrade or fail, reactant gases leak or are mixed, it can degrade the membrane electrode assembly (MEA), leading to a performance decrease in fuel cell stack performance. This portion of the research used degradation studies of certain proprietary elastomeric materials used as seals to investigate their overall stability and performance in fuel cell environments with applied mechanical stresses. Additionally, characterization of the mechanical and viscoelastic properties of these materials was conducted in order to predict the durability based on accelerated aging simulations as well. Continuous stress relaxation (CSR) characterization was performed on molded seals over a wide range of aging conditions using a customized CSR fixture. The effects of temperature, stress, and environmental conditions are reported in terms of changes in momentary and stress relaxations, chain scission and secondary crosslink formation. Aging studies provided insights on how anti-degradants or additives affect the performance and properties of sealing materials, as well as how a variety of environmental considerations might be improved to extend the lifetime of these elastomers.Ph. D.
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Senate, University of Arizona Faculty. « Faculty Senate Minutes November 6, 2017 ». University of Arizona Faculty Senate (Tucson, AZ), 2017. http://hdl.handle.net/10150/626195.
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Wu, Jun. « Greener Surface Active Reagents : Structure, Property and Performance Relationships ». Thesis, 2013. https://doi.org/10.7916/D8NP22CB.
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Surfactants are used in many industrial applications, such as flotation, flocculation, water treatment, enhanced oil recovery, emulsification, drug delivery, personal care, detergency, chemical mechanical polishing, etc. The design, development, and characterization of greener surfactants in their applications are required to meet the increasing requirements for environmental protection and an escalating demand from the society for sustainable development. It is a challenge currently to develop structure-property-performance relationships for surfactant mixtures containing greener reagents to obtain maximum efficiency with minimum environmental damages. Even though conventional surfactants and their mixtures are well studied, the fundamental studies of the structure, property and performance relationships for greener surfactants when used individually or in combination with others are just started as more and more attentions are focusing on this area. In this work, solution behaviors of surfactant systems containing several amino acid based greener surfactants have been systematically investigated using various techniques, including surface tensiometry, fluorescence spectroscopy, analytical ultracentrifugation, viscometry and computer simulation to obtain information of the structures of the aggregates formed by greener surfactants or their mixtures with conventional ones in solutions. This comprehensive study helps to elucidate the mechanism of micellization behaviors of the greener surfactant mixtures and understand the roles of molecular structures and interactions in determination of system properties and performance. The colloidal and interfacial properties of a series of lipopeptides synthesized by chemo-enzymatic reactions were studied. They were found very surface active, especially C12/oligo(L-Glu). The effects of chain length of hydrophobic moiety, composition of oligopeptide as well as aqueous chemical conditions, such as pH, on the interfacial properties of the lipopeptides were studied. Results showed the mechanism of how the interfacial and colloidal properties of amino acid based surfactants can be fine tuned by adjusting structures of the molecules. Two new surfactants, Surfactin and FA-Glu, synthesized by genetically engineered bacteria were also evaluated. Both of them showed exceptional surface activity. Genetic engineering also showed its advantages when it was found that Surfactin was limited by its solubility. Quick modifications were made in the bacteria and better option FA-Glu was produced with improved structure for better solubility. The results provide fundamental knowledge of those greener surfactants on their structure-property relationships. A number of amino acid based greener surfactants with systematic structural variations, including sodium lauroyl glutamate (C12Glu), sodium lauroyl alaninate (C12Ala), sodium lauroyl sarcosinate (C12Sar), and sodium lauroyl glycinate (C12Gly), were tested as triblend mixtures with dodecyl glucoside (C12G1) and lauramidoproply betaine (LAPB) to evaluate their performance as a function of their molecular structures. The C12Gly/C13G1/LAPB system was confirmed to have very high viscosity compared to the other systems. It was found the following micellar evolution processes happened in this system that delivered the high viscosity: small spherical micelles evolved into elongated rod-like micelles in the low concentration range, and networks of worm-like micelles formed in the high concentration range. The unique properties achieved by this system were attributed to the packing of the surfactant molecules in the system. Further results confirmed that C12Gly has a desired structure with a packing parameter of 0.4 which favors formation of worm-like micelles. Foaming performance of the selected greener surfactant was also evaluated to compare with commercial benchmark system. Even though sodium dodecyl glycinate itself is not a good foaming agent as the petroleum based non-green surfactant sodium lauryl ether sulfate, when it is mixed with the other two ingredients, significant improvement can be achieved for both foamability and foam stability due to strong synergistic interactions among them. The mixture of sodium dodecyl glycinate, dodecyl glucoside and lauramidopropyl betaine actually can deliver equal viscosity, foamability and foam stability as the benchmark system, which makes this system a leading option for the future formulations in personal care industry. Computer simulation as a powerful tool was used to understand the mechanism how greener surfactant molecules interacted with each other and how they aggregated into micelles from molecular level. Simulation found that when different surfactant molecules were mixed together, the synergistic interaction reduced the electrostatic repulsion between molecules, which led to reduction of the effective space occupied by head groups making the two head groups overlapping on each other partially. The overlapping led to a close packing of molecules. The results suggest that geometry of molecules and the interactions among them play equally important roles in determining the packing of surfactants and in turn the packing controls properties and performance of the whole system. Thus a new formula for effective packing parameter of surfactant mixtures was proposed, in which not only the geometries of molecules but also the interactions among them were included to calculate the effective packing parameter for surfactant mixtures for better predictions of the properties and performance of surfactant mixture systems. The fundamental and systematical work accomplished through this work will have a profound impact on the understanding of greener surfactant mixture systems, as structure, property and performance relationships developed herein will in turn direct the use of greener surfactants in future applications for efficiency and low chemical footprint
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ZHANG, JIAN-CHENG, et 張建成. « Processing-structure-property relationships of a high-performance epoxy system ». Thesis, 1992. http://ndltd.ncl.edu.tw/handle/66297819669597437849.
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Wang, Hsin-Ju, et 王欣如. « Structure, Conduct, and Performance of the Taiwan Property Insurance Industry ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58966747863749668037.
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碩士立德大學
國際企業管理研究所
98
The home produces the dangerous company emphatically in factors and so on managed capacity, market size, investment ability, demonstrated after in 1994 the comprehensive opening produced the danger industry, the market long-term excessive competition, produced the dangerous company's management question often to discuss, our country manufacturer started emphatically in the managerial effectiveness improvement, produced the dangerous company really in the foreign merchant, but regarding the city occupying rate maintenance and the growth was still the value very. This research is produces the danger industry take Taiwan area as a sample, discusses Taiwan area to produce the danger industry market mechanism, the behavior and the achievements relatedness, therefore uses in the industrial economics “the market mechanism - behavior - achievements” the basic idea and the construction, the establishment contains Taiwan area to produce the danger industry market concentration degree, the manufacturer competition behavior and the market achievements analysis pattern carries on the empirical analysis, understood that produces the danger industry “the market mechanism - behavior - achievements” between relations. Strategy behavior which “the structure - behavior - achievements” the theory discussion manufacturer adopts by the industrial economics, then discusses the market mechanism, the behavior and achievements three correlational. Findings demonstration (1). the staff population many does not profits the occupying rate enhancement. (2). the multiple-angle degree and enters (capital) to be higher, this expression produces the dangerous company to belong to the high capital denseness to produce, then must penetrate the multiple-angle strategy, expands its enterprise domain. (3). Taiwan produces the danger industry profit margin to be higher, then city occupying rate is higher, therefore, produces the danger industry to expand its enterprise percentage to probably carry on the profit rate promotion extremely. (4). the company multiple-angle degree recovers Gao Shiqi to produce dangerous the achievements to be better, but is higher time, its achievements instead decline. In view of the findings, according to the literature discussion proposed that the concrete proposal gives entrepreneur of the management property insurance to refer
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萬信宏. « The Physical Property and Structure of High Performance Carbon Paper ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/72013953053063453105.
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Stringer, Craig J. « Structure-property-performance relationships of new high temperature relaxors for capacitor applications ». 2006. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1609/index.html.
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Rao, YuanQiao. « The property and structure evolution with external stimuli in high performance fibers ». 2000. https://scholarworks.umass.edu/dissertations/AAI9978541.
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This dissertation presents an investigation on the long-term behavior and the structure-property relation in high performance polymeric fibers. These fibers have wide applications in structural cable and ropes and reinforced composites. Therefore, the understanding of their structure-property relation and their behavior under external mechanical stress is very important. The fatigue and creep behavior were studied. A general lifetime equation was derived to correlate the material lifetime with the applied stress level. The failure criterion of “critical strain” was identified. The failure mechanism was shown to be a deformation route. The fatigue lifetime was predicted from known material constants. Several material parameters were defined to characterize the fatigue and creep properties. The fatigue property is characterized by the fatigue strength and fatigue strength index; while the creep property is characterized by the creep strength and creep strength index. The fatigue strength index was used to show that fiber with a rigid chain structure, such as Kevlar®, Techanora ® and Vectran®, generally have better fatigue resistance than a flexible chain fiber, such as Spectra®. Twisting was found to influence yarn properties. A model based on composite theory was developed to predict the change in the yarn modulus with the degree of twist. The desire for nondestructive prediction of the residual lifetime of a used material initiated the efforts to find a signature of the stress and thermal history in Kevlar® fibers. To achieve this, a new testing methodology has been developed. An iso-strain force-temperature test (IFTT) was shown to yield quantitative information on the stress and thermal history as well as the information of relaxation and transitions in many materials. The IFTT behavior of a Kevlar® fiber maps well with its structure examined by X-ray diffraction. The IFTT was also used to screen the processing for property enhancement via post-treatment. Different post-treatment routes have been investigated for Kevlar ® fiber. Tension, heat, hydrostatic pressure, and different media of water, mercury and silicon oil have been utilized to alter the materials. The evolution of its property and structure have been carefully examined. It is shown that the modulus of PPTA is determined by two structure parameters: misorientation and a paracrystalline parameter.
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ISLAM, EHTESHAMUL ISLAM. « BENCHMARKING STUDY OF VARIOUS COMMERCIAL POLYPROPYLENE RAFFIA GRADES AVAILABLE IN INDIAN MARKET ». Thesis, 2012. http://dspace.dtu.ac.in:8080/jspui/handle/repository/13907.
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M.TECHUnder this research work ten different commercially available polypropylene homopolymer Raffia grades were taken. The main objective of this study was to establish „Structure-Property-Performance‟ relationship. “Performance” refers to their processability and runnability at higher line speed (Extrusion Tape Line). Therefore, trial runs were conducted on these PP raffia grades in order to analyze their performances. It was found that some grades, namely, PP/R/R-036 & PP/R/H-031 run very well at higher line speeds of 415mt/min and 365mt/min respectively, when compared to other grades, namely, PP/R/I-071, PP/R/I-075 and PP/R/I-027. The major problems found with PP/R/I-071, PP/R/I-075 and PP/R/I-027 grades during the trial run were the tape breakage, higher power consumption, higher water carry-over etc. Therefore, to ascertain the root cause of the inferior performance of PP/R/I-071, PP/R/I-075 and PP/R/I-027 a detailed “Benchmarking” study on these PP-raffia grades, were undertaken. Each grade was characterized in detailed using MFI & MFR, Capillary Rheometer, Differential Scanning Calorimetry, Oxygen Index Test, Dynamic Mechanical Analyzer, Dynamic Rotational Rheometer and HT-GPC techniques. On comparing the characteristics of these grades it was found that the PP/R/R-036 and PP/R/I-089 grades were having the good combination of higher modulus; low melt viscosity, higher melt elasticity and high crystallinity, than other grades, mainly due to the differences in various aspects such as high molecular weight tail, high and low molecular weight fractions at very low concentration, molecular weight distribution. Polypropylene raffia grades such as PP/R/R-036 and PP/R/I-089 have very limited high molecular weight tail with moderately broad molecular weight distribution. It is worth mentioning here that PP/R/I-075, PP/R/I-071 and PP/R/I-027 comparatively have very high molecular weight tail. These long molecular weight fractions will reduce the overall crystallinity by reducing the enthalpy. In addition to that, grades with comparatively broad molecular weight distribution have shown better processability and flowability. The presence of high molecular weight fractions at low concentration also play detrimental role during the orientation and annealing process, as in the case of PP/R/R-036 and PP/R/I-089 in the tape extrusion process.
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Hu, Yu Ning, et 胡育寧. « Merger and Acquisition, Market Structure and Performance in Property-Liability Insurance : Evidence from Taiwan Market ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/41842838343742150408.
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碩士國立政治大學
風險管理與保險研究所
96
This thesis analyzes concentration effects of merger and acquisition measured by Herfindahl index in Taiwan property-liability insurance industry. The relationships between market structure and underwriting performance are also analyzed for the time period 2000 to 2006 by testing two hypotheses: structure-conduct-performance (SCP) hypothesis which developed by Mason (1939), Bain (1956), and Scherer (1970) and relative market power (RMP) hypothesis which proposed by Rhoades (1985). The SCP hypothesis proposed that concentration is positively related to performance while the RMP hypothesis asserts that market share is positively related to performance. Implications of study results are: (1) Concentration level experiences increase from 0.0800 in 2000 to 0.0913 in 2006. Bonding & credit, fire, automobile, engineering, liability and marine cargo insurances trends to increase in concentration over the time period, whereas accident, fishing vessel, others, marine hull and aviation insurances trends to decrease; (2) The SCP hypothesis is supported. Concentration level is positively related to underwriting performance with p-value of 0.004. Higher concentration level and positive concentration-performance relationship infer that merger and acquisition activities would have positive effects upon firm performance.
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Lu, Chun-Chan, et 盧坤泉. « A Study on the Relation Between Market Structure and Performance of Property Insurance Industry in Taiwan ». Thesis, 1998. http://ndltd.ncl.edu.tw/handle/80407620815961309882.
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Chen, Shu-Hui, et 陳淑惠. « The Study of The Interrelationships Between Organizational Structure and Performance In The Property-Liability Insurance Companies ». Thesis, 1998. http://ndltd.ncl.edu.tw/handle/91753777186955708141.
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Ojala, Antti. « Merocyanine Dyes as Donor Materials in Vacuum-Deposited Organic Solar Cells : Insights into Structure-Property-Performance Relationships ». Doctoral thesis, 2012. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-70073.
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In this study, a double-donor concept is used to improve the performance of thermally evaporated merocyanine(s)/C60 bulk heterojunction (BHJ) solar cells. It is shown that the co-evaporation of two merocyanine dyes with absorption bands at ~ 500 nm (SW dye) and ~ 650 nm (LW dye), respectively, together with C60 fullerene results in an improvement of open-circuit voltage (VOC), short-circuit current (JSC) as well as total power conversion efficiency (PCE) compared to the best single-donor cell. The enhancement of JSC is attributed to a higher photon harvesting efficiency of the mixed-donor devices due to a better spectral coverageIm Rahmen dieser Arbeit wurden Struktur-Eigenschafts-Beziehungen zwischen der Festkörpermorphologie und der Leistung organischer Solarzellen auf der Basis von Merocyanin-Farbstoffen untersucht. Verschiedene analytische Methoden, vor allem optische Untersuchungen und Röntgenbeugung, wurden verwendet, um die Einkristall bzw. Dünnschichtstruktur der Merocyanine aufzuklären. Zusammenhänge zwischen der Festkörperstruktur der Farbstoffe und deren Leistung in Solarzellen wurden eindeutig nachgewiesen. In Kapitel 2 werden die Grundlagen der organischen Photovoltaik erläutert und ein Überblick über den Stand der Forschung auf dem Gebiet der durch Vakuumabscheidung von kleinen Molekülen hergestellten Solarzellen gegeben. Die Technologie der Vakuumverdampfung kleiner Moleküle hat sich in den letzten Jahren rasch weiterentwickelt und steht inzwischen an der Schwelle zur Kommerzialisierung erster Produkte. Vakuumabgeschiedene Solarzellen lassen sich mit hoher Reproduzierbarkeit herstellen und weisen gute Stabilitäten auf. Aus wissenschaftlicher Sicht ist vor allem die gute Verfügbarkeit zahlreicher Donoren und die einfache und exakte Realisierung verschiedenster Bauteilarchitekturen von Interesse. Im Kapitel 3 werden die in dieser Arbeit benutzten Architekturen für die Herstellung und Charakterisierung der Solarzellen vorgestellt und diskutiert. Kapitel 4 präsentiert eine umfassende Studie über die Kristallpackungen der dipolaren Merocyanin-Farbstoffe. Hier wurde vor allem die Wirkung der Dipol-Dipol-Wechselwirkungen auf die gefundenen Strukturmotive in den Kristallstrukturen der Merocyanin-Farbstoffe analysiert. Die statistischen Auswertung zeigt, dass bei einem hohen molekularen Dipolmoment (> 8 D) die Wahrscheinlichkeit für die Anordnung der Moleküle in einer zentrosymmetrischen Raumgruppen erhöht wird. Dimere mit einer antiparallelen Orientierung der Dipolmomente wurden häufig gefunden (Abbildung 1a). Eine detaillierte Untersuchung der Kristallstrukturen zahlreicher Merocyanine, in denen Fischerbase als Donor-Baustein in Kombination mit
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Selli, Daniele. « Structure Property and Prediction of Novel Materials using Advanced Molecular Dynamics Techniques : Novel Carbons, Germaniums and High-Performance Thermoelectrics ». Doctoral thesis, 2013. https://tud.qucosa.de/id/qucosa%3A28234.
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By means of advanced molecular dynamic techniques, we predict the stability of novel materials based on carbon, germanium and PbSe. This topological solutions have been studied and characterised at a DFT/DFTB level of theory and interesting optical, mechanical, electronic and heat transport properties have been pointed out.
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Gabriel, Brian M. Wolfe Douglas E. « Synthesis-structure-property-performance relationships of tin, CrN, and nanolayer (Ti,Cr)N coatings deposited by cathodic arc evaporation for hard particle erosion resistance ». 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-3477/index.html.
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Ho, Thanh Thuy. « The impact of taxation reforms and other factors on the capital structure of real estate enterprises ». Thesis, 2008. https://vuir.vu.edu.au/15510/.
Texte intégralRésumé :
This study investigates the impact of the New Tax System and other factors on the capital structure of the Australian listed real estate property enterprises. Hypotheses utilising Static Trade-off, Pecking Order and Market Timing theories are empirically examined using a series of the taxes variables (i.e., effective tax rate and non-debt tax shields); firm characteristics (such as size, asset structure, profitability, growth and business operation risk); and the market timing theory-related determinants such as interest rate and Market Performance Index.
The empirical tests comparing the three examined periods namely NTS, Post-NTS1 and Post-NTS2 produced a mixed result. The positive relationships were found between the leverage and the tax factors, asset structure, size, profitability and market performance in the NTS period. Negative relationships were found between the leverage and effective tax rate, growth opportunity and business operation risk. The results in the Post-NTS1 and Post-NTS2 are almost opposite to the findings in the NTS period. The most important finding in this period is the significant impact of the interest rate. The relationship between leverage and the interest rate is positive and significant, reflecting the debt-relying policy of the real estate property enterprises. In general, the findings suggest that changes resulting from the introduction of the New Tax System are positively related to the capital structure decisions of real estate property enterprises in the 1998-2002 and 2001-2003 periods. The changes in the capital structure of the sampled enterprises in the 2004-2006 period were impacted mainly by the low interest rate. The findings generally support the static Trade-off, Pecking Order, Agency Costs and Market Timing theories of capital structure.