LFC is cementatious material integrated with mechanically entrained foam in the mortar slurry which can produce a variety of densities ranging from 400 to 1600 kg/m3. The application of LFC has been primarily as a filler material in civil engineering works. This research explores the potential of using LFC in building construction, as non-load-bearing partitions of lightweight load-bearing structural members. Experimental and analytical studies will be undertaken to develop quantification models to obtain thermal and mechanical properties of LFC at ambient and elevated temperatures. In order to develop thermal property model, LFC is treated as a porous material and the effects of radiant heat transfer within the pores are included. The thermal conductivity model results are in very good agreement with the experimental results obtained from the guarded hot plate tests and with inverse analysis of LFC slabs heated from one side. Extensive compression and bending tests at elevated temperatures were performed for LFC densities of 650 and 1000 kg/m3 to obtain the mechanical properties of unstressed LFC. The test results indicate that the porosity of LFC is mainly a function of density and changes little at different temperatures. The reduction in strength and stiffness of LFC at high temperatures can be predicted using the mechanical property models for normal weight concrete provided that the LFC is based on ordinary Portland cement. Although LFC mechanical properties are low in comparison to normal weight concrete, LFC may be used as partition or light load-bearing walls in a low rise residential construction. To confirm this, structural tests were performed on a composite walling system consisting of two outer skins of profiled thin-walled steel sheeting with LFC core under axial compression, for steel sheeting thicknesses of 0.4mm and 0.8mm correspondingly. Using these test results, analytical models are developed to calculate the maximum load-bearing capacity of the composite walling, taking into consideration the local buckling effect of the steel sheeting and profiled shape of the LFC core. The results of a preliminary feasibility study indicate that LFC can achieve very good thermal insulation performance for fire resistance. A single layer of 650 kg/m3 density LFC panel of about 21 mm would be able to attain 30 minutes of standard fire resistance rating, which is comparable to gypsum plasterboard. The results of a feasibility study on structural performance of a composite walling system indicates that the proposed panel system, using 100mm LFC core and 0.4mm steel sheeting, has sufficient load carrying capacity to be used in low-rise residential construction up to four-storeys.

The high temperature, high pressure electrochemical behavior of A516 Gr. 70 carbon steel in aqueous alkaline sulfide solutions was studied by means of polarization tests and cyclic volt-ammetry. The effects of variation of temperature (90-150°C), sulfide concentration (0-3 m), scan rate (1-50 mV/s) and scan range, and the effects of stirring and polarization at the switching potentials between scans were investigated. Passivation was consistent with formation of a protective Fe₂O₃ film. An understanding of the electrochemical behavior of iron in the alkaline sulfide solutions was facilitated by the construction of E-pH diagrams for S-H₂0 and Fe-S-H₂O systems at 25, 100 and 150°C. Sulfide, S²-, currently considered to be stable only at extremely high pH, was excluded from the E-pH diagrams. Reference electrodes, compatible with sulfide solution, were designed for use with an autoclave. The response of the Ag/Ag₂S electrode (SSSE) to variation of temperature, sulfide and hydroxide concentration, and chloride addition was studied. Liquid junction potential and thermal liquid junction potential corrections were applied. The SSSE was not reliably predictable thermodynamically, but was stable and was proven effective in the polarization study. The electrochemical potentials of inert metal reference electrodes, Hg and Pt, were found to be consistent with the mixed potential between polysulfide Sײ⁻, and thiosulfate, S₂O₃²⁻. The Tafel slopes from anodic polarization curves of Pt in alkaline sulfide solutions were consistent with oxidation of HS⁻ to S₂0₃²⁻ at the mixed potential. At more noble potentials, oxidation to polysulfide occurred. Reaction path mechanisms were proposed. Understanding of sulfide oxidation aided in interpretation of the electrochemical behavior of steel in the alkaline sulfide solutions. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

Five formula methods and three numerical general methods for determining thermal process lethality were compared with a reference method to demonstrate their applicability to conduction heating foods in cylindrical containers. Hypothetical centerpoint temperature history curves for cans with height to diameter (H/D) ratios of 0.1 to 3.0 were generated for a range of processing conditions using computer simulation. A finite-difference model based on Teixeira et al. (1969b) was used as the basis of the simulation program. The delivered lethality to an organism characterized by Z=10C° was evaluated using each of the methods and compared to the lethality calculated using the reference method. For each of the test methods, simulation data were provided for one minute intervals, but for the reference method, data were provided for intervals of 0.05 min. Each of the selected formula methods was adapted to allow calculations to be done by computer without operator intervention. The most significant part of this adaptation was the development of a system that enabled the computer to select the linear portion of the heat penetration curve to facilitate calculation of the parameters f and j which are required by all of the formula methods. A method for handling large tables was also developed for use with some of the formula methods. For the general methods, the deviations from the reference method were greatest when the heating rate index (fh) and H/D were small and the unaccomplished temperature difference (g) was large. Whereas the the value of fh was the most significant factor affecting the accuracy of calculations done using the general method, it did not greatly affect the performance of the formula methods. The factors that most significantly influenced deviations between the formula methods and the reference method were H/D and g. The largest deviations in all cases occurred when g was large and H/D was close to unity. These errors were mostly on the "safe" side, but the energy use implications could be significant, especially for high retort temperature processes. / Land and Food Systems, Faculty of / Graduate

The sample used for evaporative cooling system is Fabric defender 750 with Shelltite finish. From the experimental data and equations we have diffusion coefficient of 20.9 ± 3.71 x 10-6 m2/s for fabric with one layer with 17%-20% fluctuations from the theory, 27.8 ± 4.5 x 10-6 m2/s for fabric with two layers with 6%-14% fluctuations from the theory and 24.9 ± 4.1 x 10-6 m2/s for fabric with three layers with 13%-16% fluctuations from the theory. Since the thickness of the fabric increases so the mass transport rate decreases so the mass transport resistance should be increases. The intrinsic mass resistances of Fabri-1L, Fabri-2L and Fabri-3L are respectively 104 ± 10.2 s/m, 154 ± 23 s/m and 206 ± 26 s/m from the experiment.

Melting of elemental solids can be identified and appreciated as a particularly simple example of discontinuous phase transitions involving condensed phases. Motivated, on the one hand, by the need to improve the microstructural quality of laser-crystallized columnar-grained polycrystalline Si films for manufacturing advanced AMOLED displays and, on the other hand, to investigate the fundamental details associated with phase transformations transpiring in condensed systems, this thesis examines the initiation and evolution of melting in polycrystalline thin films. Distilling the essence of the classical nucleation theory and extending its description to address more general cases of phase initiation and evolution, a general thermodynamic method based on capillarity effect is developed and applied to determine the shape of solid/liquid interfaces that are in mechanical equilibrium. We first explicitly identify and build our analysis based on how the shape of solid/liquid interfaces must comply with the contact angle conditions at the junctions and also the property of constant mean curvature. Bi-crystal and tri-crystal models are presented to capture the microstructural features such as junctions and vertices of interfaces in polycrystalline thin films. At each of the potential melt initiating sites, the parameter space of contact angles is divided into domains depending on the shape of the solid/liquid interface that can be established in mechanical equilibrium. Melting initiation mechanisms are subsequently determined based on the permissible shape for each domain. This analysis is further extended to the edges and corners of embedded cubic crystals (with nonidentical contact angles at different faces). Secondly, in order to facilitate the thermodynamic analysis of the melting initiation and interface propagation, we extend our curvature-evolution-centric method to identify and develop what we consider as the central function for discontinuous phase transitions. Specifically, starting with a local governing condition, identifies and builds on two curvatures: ρ^E (𝑉) and ρ* (𝑇). ρ^E (𝑉) captures the evolution of the mean curvature of the solid/liquid interface as a function of liquid volume for the case in which the mechanical equilibrium condition is satisfied, whereas ρ* (𝑇) incorporates the temperature effect on the difference between the volumetric free energy of solid and liquid phases using the corresponding equilibrium mean curvature. We define and identify the interface driving stress function ƒ(𝑉,𝑇)=∂𝐺/∂𝑉=σ(ρ^E (𝑉)-ρ* (𝑇)) of the phase transition as being an important fundamental quantity, which can be directly derived by taking the difference of the two curvature terms. In contrast to the conventional analysis that requires integration of volumetric and interfacial free energy terms over various geometric domains to derive the total free energy as a function of volume for a given temperature, this formation completely disentangles geometry from the thermodynamic aspects of the phase transition and allows them to be treated separately. In addition to providing essentially all relevant thermodynamic information about the phase initiation and evolution, the above method readily permits the use of powerful general-purpose numerical tools to calculate the potentially complex geometry of the solid/liquid and other interfaces and obtain ρ^E (𝑉) directly as the output. Plotting the ρ^E (𝑉) function together with the temperature-dependent iso-curvature line, ρ* (𝑇), unveils the critical thermodynamic information regarding the melting transition at the temperature, such as whether equilibrium points exist, the number of equilibrium points, their stability, and their corresponding volumes. The change of free energy as a function of liquid volume can be derived through integration of the interface driving stress function. The velocity of the solid/liquid interface is simply proportional to the interface driving stress function. The application of this method is demonstrated in both shape-preserving (which we term as isomorphic) and shape-changing (which we term as non-isomorphic) examples. The analysis and findings presented in this thesis are relevant and useful for understanding discontinuous phase transitions, in general, and can be particularly so for small, confined, and embedded systems that are increasingly being utilized in modern technologies.

The purpose of this thesis is to investigate the correlated effects of temperature and frequency on the viscoelastic behavior of magnetic tapes, using a custom, ultra-low frequency, dynamic mechanical analyzer. The long-term mechanical and thermal properties of magnetic tapes can be simulated using high temperature and low frequency dynamic mechanical analysis (DMA) experiments. These experiments investigate how the viscoelastic characteristics of tape samples influence the extent to which the tape deforms. The experiments and analyses implemented in this paper examine the influence of the molecular structure on the viscoelasticity of magnetic tapes. Experiments were performed on a variety of magnetic tapes, including poly( ethylene terephthalatc) (PET), poly( ethylene naphthalate) (PEN), metallized poly( ethylene terephthalate) (MPET), and metallized Spaltan (M-SPA). To determine characteristic relating to the magnetic tape substrates, additional experiments examined PEN and PET substrates by removing the front and back magnetic layers from the tape sample. Due to the viscoelastic behavior of the tapes, a time delay was present between the strain and stress signals, which was determined using a Fourier transform program. The elastic modulus (E), storage modulus (E'), loss modulus (E"), and loss tangent (tan 8) were obtained from the time delay for each of the DMA experiments

III-nitride nanostructures have generated tremendous scientific and technological interests in studying and engineering their low dimensional physics phenomena. Among these, 2D planar, free standing III-nitride nanomembranes are unrivalled in their scalability for high yield manufacture and can be mechanically manipulated. Due to the increase in their surface to volume ratio and the manifestation of quantum phenomena, these nanomembranes acquire unique physical properties. Furthermore, III-nitride membranes are chemically stable and biocompatible. Finally, nanomembranes are highly flexible and can follow curvilinear surfaces present in biological systems. However, being free-standing, requires especially new techniques for handling nanometers or micrometers thick membrane devices. Furthermore, effectively transferring these membrane devices to other substrates is not a direct process which requires the use of photoresists, solvents and/or elastomers. Finally, as the membranes are transferred, they need to be properly attached for subsequent device fabrications, which often includes spin coating and rinsing steps. These engineering complications have impeded the development of novel devices based on III-nitride membranes. In this thesis, we demonstrate the versatility of III-nitride membranes where we develop a thermal bio-sensor nanomembrane and solar energy photo-anode membrane. First, we present a novel preparation technique of nanomembranes with new characteristics; having no threading dislocation cores. We then perform optical characterization to reveal changes in their defect densities compared to the bulk crystal. We also study their mechanical properties where we successfully modulate their bandgap emission by 55 meV through various external compressive and tensile strain fields. Furthermore, we characterize the effect of phonon-boundary scattering on their thermal properties where we report a reduction of thermal conductivity from 130 to 9 W/mK. We employ these modifications to develop a thermal biosensor, which conformally gets attached to cells to measure their thermal properties. We also assess the statistical significance of our measurements to differentiate between different cell lines based on their measured thermal properties. Finally, we demonstrate the application of nanomembranes in solar-based water-splitting by merging them with nanowires to form nanowire membranes which are used to fabricate membrane photo-anodes. Finally, through optical, chemical and electrochemical measurements, we demonstrate their superior operations compared to typical fabrication techniques.

Thesis. 1976. Nucl.E.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / Microfiche copy available in Archives and Science. / Includes bibliographical references. / by Pablo Moreno. / Nucl.E.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13102号 / 論農博第2848号 / 新制||農||1051(附属図書館) / 学位論文||H29||N5034(農学部図書室) / (主査)教授 矢野 浩之, 教授 金山 公三, 教授 辻井 敬亘 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

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