Dissertations / Theses on the topic 'Isothermal conditions'
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Phusunti, Neeranuch. "Pryolytic and kinetic study of Chlorella vulgaris under isothermal and non-isothermal conditions." Thesis, Aston University, 2013. http://publications.aston.ac.uk/19227/.
Full textAshraf, Muhammad. "Dynamics of soil water under non-isothermal conditions." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336299.
Full textLin, Rongjau. "Experimental and numerical analysis of RTM and SRIM processes in non-isothermal conditions /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu148769470278441.
Full textSchaffer, Joseph F. "Verification and Adaptation of an Infiltration Model for Water at Various Isothermal Temperature Conditions." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1061.
Full textEsmele, Myles. "A model for deformation of continuous fiber composites under isothermal creep and thermal cycling conditions." Monterey, Calif. : Naval Postgraduate School, 1997. http://handle.dtic.mil/100.2/ADA363934.
Full textVeltzke, Thomas [Verfasser], Jorg [Akademischer Betreuer] Thöming, and Michael [Akademischer Betreuer] Schlüter. "On gaseous microflows under isothermal conditions / Thomas Veltzke. Gutachter: Jorg Thöming ; Michael Schlüter. Betreuer: Jorg Thöming." Bremen : Staats- und Universitätsbibliothek Bremen, 2013. http://d-nb.info/1072047489/34.
Full textBartolotta, Paul Anthony. "Fatigue behavior and life prediction of a silicon carbide/titanium-24aluminum-11niobium composite under isothermal conditions." Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055531339.
Full textChen, Guang. "An investigation into nano-particulates reinforced SAC305-based composite solders under electro- and thermo-migration conditions." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27576.
Full textBen, Haj Slama Meriem. "Étude multi-échelle et in situ des évolutions microstructurales en conditions isothermes d’aciers bainitiques en lattes." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0042/document.
Full textBainitic steels are widely used in industry thanks to their good combinations of strength, toughness and ductility. Meanwhile, after obtaining the targeted microstructure, the steel can undergo additional isothermal holdings (either during manufacturing and/or during usage) prone to degrade its properties. The thesis work aims at understanding the microstructural origins of this degradation. To achieve this, we applied controlled heat treatments on model FeNiC and FeNiMnC steel grades. A first set of heat treatments allowed us to obtain different microstructures; upper and lower bainites, martensite and mixed concepts. These transformation products were characterized and analyzed in detail, particularly by EBSD with improved angular resolution. Data was operated to reconstruct prior austenitic grains and to distinguish the different transformation products according to their crystallographic variant spatial organization. A second set of heat treatments consisted in aging these microstructures by extended isothermal holdings. We show that lath-like bainitic microstructures are not stable under certain isothermal conditions. In the most advanced cases, we observed a « granularization » process of the lath microstructure, associated with high misoriented variant disappearance and carbides ripening. These phenomena were observed for the studied model alloys, even within short holding times (<1h) and at low temperatures (300°C). These highlighted evolutions as well as their kinetics were investigated at different scales, coupling SEM observations, EBSD, TEM and in situ XRD High Energy on large instruments. The initial microstructure and the steel chemical composition affect significantly the « granularization » kinetics. But we have above all put the light on the major role of the presence of an upper bainite fraction (even a residual one) in the initial microstructure, to start the granularization phenomenon, independently of aging temperature. All of these results allow discussing possible mechanisms with their respective driving forces and opening larger discussion about bainite classification
Mathison, Randall Melson. "Experimental and Computational Investigation of Inlet Temperature Profile and Cooling Effects on a One and One-Half Stage High-Pressure Turbine Operating at Design-Corrected Conditions." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250281163.
Full textГараненко, Тетяна Романівна. "Розробка процесу формоутворення порожнистої лопатки з титанових сплавів для газотурбінних двигунів." Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/40560.
Full textDelgado, Cano Beatriz. "Caractérisation des matériaux commerciaux et synthétisés destinés à adsorber le méthane et l’oxyde nitreux présents dans des émissions gazeuses et modélisation de l’adsorption." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1073.
Full textHuman activities contributed with a significant increase in GHG concentrations over the past 150 years and they are related to environmental issues, such as global warming and climate change. The agricultural sector contributes 8 to 10% of total GHG emissions to the atmosphere, being carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) the main GHGs emitted. The control and quantification of these emissions requires technologies which can capture and or degrade these GHG, for example by adsorption. The objective of this project is to characterize adsorbents and to describe their adsorption kinetics in order to select the most suitable for the adsorption of CH4 and N2O at low concentration and at ambient temperature. For CH4 adsorption, commercial and synthesized adsorbents were tested. The selected adsorbents were commercial zeolites, laboratory conditioned biochar and synthesized ZIF ("Zeolitic imidazolate framework"). ZIF was also used for N2O adsorption. The adsorption capacity of CH4 and N2O for each adsorbent was evaluated by dynamic adsorption tests of the gas under atmospheric conditions. These materials were physically and chemically characterized in order to correlate its properties with its CH4 and/or N2O adsorption capacity. The experimental data of gas adsorption were fitted by equilibrium isotherms. Among the different materials used for CH4 adsorption at 30 ºC and partial pressures lower than 0.40 kPa, biocharbons presented the highest adsorption capacity, followed by ZIF- 8 and commercial zeolites
Edström, Emelie. "Solvent adsorption in SFC : Adsorption of methanol under supercritical conditions." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-35185.
Full textMuller, Laëtitia. "Etude expérimentale de l'interaction flamme-paroi instationnaire dans des conditions initiales non isothermes." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. http://tel.archives-ouvertes.fr/tel-00743578.
Full textDjikaev, Yuri. "Cinétique de la nucléation binaire non-isotherme et de la condensation binaire aux conditions dynamiques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0028/NQ48764.pdf.
Full textGiraud, Stephen. "Croissance de couches minces de silicium pour applications photovoltaïques par epitaxie en phase liquide par évaporation du solvant." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI057/document.
Full textCrystalline Si thin films on low-cost substrates are expected to be alternatives to bulk Si materials for PV applications. Liquid Phase Epitaxy (LPE) is one of the most suitable techniques for the growth of high quality Si layers since LPE is performed under almost equilibrium conditions. We investigated a growth technology which allows growing Si epitaxial thin films in steady temperature conditions through the control of solvent evaporation from a metallic melt saturated with silicon: Liquid Phase Epitaxy by Solvent Evaporation (LPESE). We studied the main requirements regarding selection of solvent, crucible and growth ambient, and a first experimental set up is designed. An analytical model is described and discussed, aiming to predict solvent evaporation and Si crystallization rate. Growth experiments are implemented with a vertical dipping system. Growth procedure is presented and the influence, on Si growth, of melt convection, temperature gradient in the melt and Si-M reactivity with the material crucible are discussed. Solutions are proposed to improve and optimise the growth conditions. Experimentally, Si thin films were grown from Sn-Si and In-Si solution at temperatures between 900 and 1200°C under high vacuum. We are able to achieve epitaxial layers of several micrometers thickness (20-40µm). The predicted solvent evaporation rate and Si growth rate are in agreement with the experimental measurements. Regarding the structural quality, it is comparable to the crystal quality of layers grown by LPE. With In and In(Ga) melts, we can obtain P-type epitaxial layers with doping level in the range 1017 at.cm3, which is of great interest for the fabrication of solar cells. Finally, the growth of Si thin films on multicrystalline Si substrates by LPESE is discussed to assess the potential application of this technique
Kadoun, Abd-Ed-Daim. "Optimisation des conditions du recuit rapide isotherme sur substrats InP encapsulés InGaAs pour application aux composants avancés." Lyon, INSA, 1994. http://www.theses.fr/1994ISAL0036.
Full textWe started this work by are research on the optimised annealing conditions in a quartz chamber lamp furnace (Addax R1000) using a sandwich or a SiC-coated graphite cell configuration, in order to minimise the degradation due to phosphorus loss. We show that an MBE-epitaxial InGaAs layer grown onto InP substrate is an efficient protection against material thermal degradation. Capacitance-voltage measurements C(V) deep level transient spectroscopy (DLTS) and photo-induced current spectroscopy (PICTS) analysis were implemented for the purpose of investigating the residual degradation in non intentionally doped (n-type) and semi-insulating De-doped substrates. The most prominent result of this study is the appearance in the undoped material of a depletion surface region which is not observed in a virgin substrate and whose thickness depends on teh process sequencies underwent by the annealed substrate. An uniform carrier compensation is observed after MBE growth. Those effects are quite correlated to the appearance in a high concentration of an Ec-0,63eV deep level, classically identified with the Fe3+/Fe2+ acceptor level which is due to the Fe on In sites in InP. This correlation is confirmed by optical spectroscopy measurements (DLOS) and secondary ion mass spectrometry analysis (SIMS). Finally, the InGaAs encapsulation was applied to the post-implantation annealing in MISFET technologies. An Fe redistribution correlated to the profiles of the implanted species is observed
Bhouri, Naoufel. "Comportement thermodynamique et dimensionnel des matériaux textiles soumis à des variations des conditions climatiques." Thesis, Nancy 1, 2009. http://www.theses.fr/2009NAN10120/document.
Full textThe 2D deformation of bleached plain weave and Jersey cotton ready to wear clothing was measured during adsorption and desorption cycles. The strain along warp and weft directions and the shear deformation were evaluated by image correlation process. The dimensional variations are explained by geometrical consideration of the structure at microscopic (fibers scale) and macroscopic levels (yarns scale). Indeed, the reaction between water vapor molecules and material enlightens two steps. At first, the swelling fibers fill the micro pores inside the yarns. Then, the yarns swell and push on their neighbors to fill up the macro pores and cause the macroscopic swelling of the overall structure. During the desorption phase, the fibers shrink to create a free space inside the plain weave structure that will be relaxed to find its initial state. The shear deformation is related to the cohesion by twist between cotton fibers. The ironing generates flattened yarns and increases their friction which amplifies the deformation during the first adsorption cycle. However, this effect is cancelled at the end of the first adsorption / desorption cycle with no memory effect of the ironing process. These results are confirmed by comparison between sorption isotherms of ironed and not ironed plain weave samples. A comparison between the sorption capacity of Jersey and yarn made of the same structure shows that the geometric form decreases the sorption capacity of jersey especially at high humidity. Then knitting infects the swelling of yarns and decreases their sorption capacity
Saidi, Fouad. "Sur quelques problèmes de lubrification par des fluides newtoniens non isothermes avec des conditions aux bords non linéaires. Etude mathématique et numérique." Phd thesis, Université Jean Monnet - Saint-Etienne, 2004. http://tel.archives-ouvertes.fr/tel-00008745.
Full textSaidi, Fouad. "Sur quelques problèmes de lubrification par des fluides newtoniens non isothermes et incompressibles avec des conditions aux bords non linéaires : étude mathématique et numérique." Saint-Etienne, 2004. http://www.theses.fr/2004STET4013.
Full textWe recall the basic principles of the continuous media its mechanics from which we deduce the equations modelling the nonisothermal flow of an incompressible newtonian fluid. We consider the stationary case in a thin domain ?e with nonlinear boundary conditions. We deduce the corresponding variational problem which is strongly coupled, composed by a variational inequality and an equality, whose unknowns are the velocity field of the fluid, its pressure and its temperature. The principal difficulty is the presence in the variational equality of the square of the deformation rate tensor, which does not make possible to give sense to the variational problem, if we search the velocity in h1 -convex. To overcome this difficulty, we search the h2 -regularity of the velocity, which requires the c0 ,1-regularity of the temperature, which is in the coefficients of the variational inequality. By using the Banach fixed point theorem, we show the existence, uniqueness and regularity of weak solution. So, we established the e-estimates of the h2 -norm for the velocity and temperature, and of the h1 -norm for the pressure. This enables us to obtain the strong limits. We then obtain the limit problem, the generalized Reynolds equation and we prove the uniqueness of solutions to this limit problem. We present also an approximation of the limit problem by the finite elements methods, we study the convergence of the approximate solutions and we give the error estimates of the approximation. Finally, we replace in preceding study the Tresca's boundary condition by Coulomb's and we obtain the similar results
Maghsoodi, Soheib. "Thermo-mechanical behavior of soil-structure interface under monotonic and cyclic loads in the context of energy geostructures." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0031.
Full textIncorporation of heat exchangers in conventional geostructures like piles can extract the heat from the soil for heating purposes and inject it to the soil for cooling purposes. In recent years, research has been conducted at full and laboratory scale to investigate the effect of temperature on the geotechnical behavior of these energy geostructures as well as on the surrounding soil. Indeed, these energy geostructures can be subjected to cyclic mechanical loads and thermal variations throughout their lifetime. The aim of this study was to deepen the understanding regarding the behavior of sand/clay-structure contact under complex thermo-mechanical loads. A temperature-controlled direct shear device to perform monotonic and cyclic constant normal load or constant normal stiffness tests was developed. The response of the interface to the thermal effects on the mechanical behaviour of soils and soil-structure interface was investigated. Fontainebleau sand and kaolin clay were used as proxies for sandy and clayey soils. The results showed that the applied thermal variations have a negligible effect on the shear strength of the sand and sand-structure interface. In clay samples the temperature increase, increased the cohesion and consequently the shear strength, due to thermal contraction during heating. The adhesion of the clay-structure interface, was less than the cohesion of the clay samples. To investigate the mechanical cyclic load effects on the clay-structure interface at different temperatures, monotonic and cyclic constant-volume equivalent-undrained direct shear tests were performed on clay-clay and clay-structure interface at different temperatures. The results showed that, the number of cycles to failure for the clay-structure interface test was lower than that for the clay-clay case in the same range of cyclic and average shear stress ratios. Increasing the temperature, decreased the rate of strain accumulation and the number of cycles to failure increased by 2-3 times. The rate of degradation (degradation parameter, t) decreased by 16% with heating from 22 to 60oC for the different cyclic stress ratios tested. A non-isothermal soil-structure interface model based on critical state theory was then developed. The non-isothermal model takes into account the effect of temperature on the void ratio of interface prior to shearing. The model is capable to capture the effect of temperature on soil-structure interface under constant normal load and constant normal stiffness conditions for both sandy and clayey interfaces. The additional parameters have physical meanings and can be determined from classical laboratory tests. The formulation is in good agreement with the experimental results and the main trends are properly reproduced
Ewart, Timothée. "Etude des écoulements gazeux isothermes en microconduit : du régime hydrodynamique au proche régime moléculaire libre." Phd thesis, Université de Provence - Aix-Marseille I, 2007. http://tel.archives-ouvertes.fr/tel-00396378.
Full textHamraoui, Mohamed. "Stabilisation des systèmes non-linéaires par retour d'état estimé. Applications aux réseaux de cinétique chimique et au traitement des eaux usées." Rouen, 1996. http://www.theses.fr/1996ROUES043.
Full textAyad, Djamel. "Etude du comportement viscoélastique linéaire du polyfluorure de vinylidène : corrélation avec sa microstructure et son aptitude à l'étirage en phase fondue." Saint-Etienne, 1996. http://www.theses.fr/1996STET4007.
Full textEl, Mir Rachid. "Etude mathématique et analyse asymptotique de quelques problèmes de lubrification par des fluides incompressibles essentiellement non-Newtoniens avec des conditions de non adhérence aux bords." Phd thesis, Université Jean Monnet - Saint-Etienne, 2005. http://tel.archives-ouvertes.fr/tel-00011638.
Full textBeaude, Laurence. "Simulation numérique d'écoulements diphasiques compositionnels thermiques en milieux poreux et ses applications à la géothermie haute énergie." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4107/document.
Full textThe study of the subsurface flows is important for various applications such as energy or nuclear waste storage. This thesis, performed in collaboration with the French Geological Survey (BRGM), is dedicated to the simulation of non-isothermal compositional two-phase flows in porous media and its applications to high-energy geothermal fields and more precisely to the Bouillante field (Guadeloupe, French West Indies). First of all, two persistent variable formulations are compared in terms of implementation and numerical convergence. In these two formulations, the choice of the principal variables is based on with the extension of the phase molar fractions by the one at thermodynamic equilibrium with the present phase. It results that the set of principal variables and equations does not depend on the set of present phases. It also has the advantage to express the thermodynamic equilibrium as complementarity constraints, which allows the use of semi-smooth Newton methods to solve the non-linear systems. Moreover, this thesis presents a new methodology to combine a node-centered discretization (the Vertex Approximate Gradient scheme - VAG) and a face-centered discretization (the Hybrid Finite Volume scheme - HFV) on arbitrary subsets of cells or faces in order to choose the best-suited scheme in different parts of the mesh. Indeed, hybrid meshes composed of different types of cells are best suited to discretize the geology and geometry of the different parts of the geothermal system. Then, the scheme is adapted locally to the type of mesh/ cells and to petrophysical properties. The convergence analysis is performed in the gradient discretization framework over second order diffusion problems and the convergence is checked numerically on various types of hybrid three-dimensional meshes. Then, the VAG-HFV discretization is extended to non-isothermal compositional liquid-gas Darcy flows and is applied on the two dimensional cross-section of the Bouillante high temperature geothermal reservoir. Another important aspect of the geothermal flows modelling consists in considering the interactions between the porous medium and the atmosphere. Since the coupling between the porous medium and the 2D surface of 3D atmospheric flows is not computationally realistic at the space and time scales of a geothermal flow, the soil-atmosphere interaction is modelled using an advanced boundary condition accounting for the matter (mole) and energy balance at the interface. The model considers an atmospheric boundary layer with convective molar and energy transfers (assuming the vaporization of the liquid phase in the atmosphere), a liquid outflow condition at seepage surfaces, as well as the heat radiation and the precipitation influx. This boundary condition is assessed using a reference solution coupling the Darcy flow to a full-dimensional gas free flow. Then, it is studied numerically in terms of solution and convergence of the Newton-min non-linear solvers on several geothermal test cases including two-dimensional simulations of the Bouillante geothermal field. In addition is presented the collaborative project which took place during the CEMRACS summer school 2016. The project consisted in adding a multibranch thermal well model into the ComPASS code, a new geothermal simulator based on unstructured meshes and adapted to parallel distributed architectures with the ability to represent fractures
Edström, Lena. "Adsorption Studies with Liquid Chromatography : Experimental Preparations for Thorough Determination of Adsorption Data." Doctoral thesis, Uppsala universitet, Analytisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-216235.
Full textGonnet, Jean-Marc. "Contrôle en ligne du moulage par injection des thermoplastiques semi-cristallins par spectroscopie diélectrique." Saint-Etienne, 2000. http://www.theses.fr/2000STET4003.
Full textCanon, Eric. "Etude mathématique de deux modèles de colonne à distiller : modèle discret à étages théoriques, modèle continu hyperbolique." Saint-Etienne, 1990. http://www.theses.fr/1990STET4004.
Full textLiao, Guo-Ting, and 廖國廷. "Thermal Decomposition Kinetics of Polyimide Polymer for Non-isothermal Conditions." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/vx389n.
Full text大同大學
化學工程學系(所)
95
Studies of non-isothermal decomposition of a new diamine monomer led to a series of novel polyimide polymer (a)-(f) when reacted with six dianhydrides were measured by thermogravimetric analysis (TGA) at a heating rate of 20℃/min in nitrogen and air atmospheres. Three single heating-rate integral methods by Coats-Redfern, Horowitz-Metzger and Van Krevelen that were analysed using the non-isothermal data with different expressions of solid state reactions, i.e., g(a) would be used to estimate the activation energy (E), pre-exponential factor (A), and order of reaction (n). The F1 and R2 models were selected as the best mechanisms for solid-state reactions to fit experimental TG curves in nitrogen and air atmospheres, individually. Mathematical verification of using different integral methods shows that the Coats-Redfern method is more precise than the Horowitz-Metzger and Van Krevelen methods since the other two methods are dependent on the arbitrary selection of the reference temperatures. From the molecular structure point of view, the order of the activation energy of polyimide under nitrogen is PI-e(DSDA) =PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-b(BPDA) >PI-c(BTDA); however, under air it is PI-f(6FDA) >PI-a(PMDA) >PI-d(ODPA) =PI-c(BTDA) >PI-b (BPDA) =PI-e(DSDA). In this study, it is found that the activation energy and pre-exponential factor show the same trend, i.e., both values increase with increasing the order of reaction for each sample, i.e., polyimide (a)-(f). On the other hand, the parameter values in air are lower than those in N2. It can be attributed to that not only the molecular structure but also combustion of oxygen would affect the value of activation energy.
王志榮. "Optimal Disigns in HDM Fixed Bed Reactor under Non-isothermal operating conditions." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/72085504530792546615.
Full textChen, Chun Hung, and 陳俊宏. "Optimal Disigns in HDS Fixed Bed Reactor under Non-isothermal Op- erating Conditions." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/52714722301878323273.
Full text國立成功大學
化學工程研究所
82
Most of the researches in the hydrodesulfurization (HDS) of the residual oil were focused on a single catalyst pellet with an uniform activ ity , or on studing the optimal initial pore size under the isothermal conditions . However the operations of HDS in the industry in practice us- ually fix the reactor outlet con centration of the sulfur-contai- ning molecules and stop the operation when the upper limiting te- mperature is reached . In this study the non-uniform activity pr- ofile of the HDS catalysts was incorporated into the restricted diffusion model proposed by Rajagoplan and Luss to examine the t- emperature- rising profile of the fixed bed reactor , and to pred- ict the optimal design of the reactor from the total amount of desulf urization under the nonisothermal operating conditions . The optimal design of the reactor includes the optimal pore size the catalysts and their corresponding optimal design in one -stage and two-stage arrangement respectively . The reaction product of the metal sulfide will accumulate on the pore surface of the catalysts during the reaction , and ther- eby reduce the HDS reaction rate . Because of this , the hydrode- metallation (HDM) reaction the residual oil was considered simul- taneously with the HDS reaction . In this study , 1st- order reac- tion for HDM and 2nd-order reaction for HDS were adopted . The numerical results have shown that the life-time and the total mass of desulfarization with the nonuniform activity catal- ysts were higher than those of the uniform activity catalysts . Although the initial temperature of the former is greater th- an that of the uniform activity catalyst , but their temperature- rising prifile is flatter than that of the uniform activity cata- lyst , and their interior activity surface can be more efficient- ly utilized to improve the catalyst life and mass of desulfuriza- tion .
Sweeney, John, Philip D. Caton-Rose, and Philip D. Coates. "Modelling the large strain constitutive behaviour of polycarbonate under isothermal and anisothermal conditions." 2005. http://hdl.handle.net/10454/750.
Full textWe have studied the tensile behaviour of polycarbonate at large strains below the glass transition temperature. Experiments have been carried out at a series of constant temperatures and also under conditions of falling temperature. The specimens neck with a natural draw ratio of ~2, and the study focuses mainly on the necked material. Isothermal experiments reveal an elastic mechanism that initiates beyond the natural draw ratio. A model consisting of an Eyring process and two Gaussian elastic mechanisms is shown to be applicable to both the isothermal and anisothermal stress relaxation and stress-strain results. The same model also produces reasonable estimates of the stresses generated during the necking process. In addition, a simple relationship between isothermal and anisothermal stress relaxation is demonstrated.
Liu, Shuo-Chi, and 劉碩琦. "Transport properties of poly(3-hydroxybutyrate-co-3 hydroxyvalerate) membranes via various isothermal crystallization conditions." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60184248073605316711.
Full text元智大學
化學工程與材料科學學系
98
The water transport properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) membranes prepared via melt- and cold-crystallization procedures were investigated. The thermal properties and crystalline structure were determined by DSC, WAXD and SAXS, the free volume properties were obtained by positron annihilation lifetime spectroscopy (PALS) and the sorption isotherm and diffusivity of water in the membranes were measured by the gravimetrical method with a recording microbalance. The results showed that the crystallinity of melt-crystallized PHBV membranes was higher than that of the cold-crystallized ones with the same crystallization temperature. The sorption data evidenced that water molecules could form clusters in the polymer matrix. The water clustering phenomenon would decrease the diffusivity of water in melt- and cold-crystallized PHBV membranes at higher activities. The water diffusivity was successfully correlated with the relative fractional free-volume (FFV) and the crystallinity using the modified free-volume theory. The sorption relaxation behavior that the sorption amount could reach a maximum and then reduced again during the sorption process was observed in this study. The changes of the crystalline structure of PHBV membranes during water desorption were analyzed. Water molecules may interact with PHBV chains and reduced the lattice parameters and size of lamellar thickness in crystalline structure.
Cheng, Wen-Seng, and 鄭文笙. "Conformation and Crystallization of Ethylene glycol/1,3-Propanediol/Dimethyl Terephthalate copolyesters Under Isothermal Crystallization Conditions." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/20302292370498704056.
Full text逢甲大學
紡織工程所
97
This study focused on conformation, crystallization, and melting behaviors of a series of (ethylene glycol/1,3-propanediol/dimethyl terephthalate) random copolyesters under isothermal crystallization conditions. The conformation and arrangement were investigated using an In-situ Fourier transform infrared spectrometer (In-situ FTIR). The crystallization and melting behaviors were studied using a differential scanning calorimeter (DSC). The crystallization kinetics was calculated as well. The structure and crystallinity were studied and measured using a wide angle x-ray diffractometer (WAXD). Based on the In-situ FTIR, DSC, and WAXD studies, it can be seen that the major constitutional repeating unit of copolyesters conducted the arrangement of molecular conformation. In ET30-ET70 (EG content: 15.0-52.7 %) copolyesters, the molecular chain arranged mainly as a gauche conformation. In ET80-ET90 (EG content: 65.9-81.6 %) copolyesters, the molecular chain arranged mainly as a trans conformation. Cold-crystallization was much faster than melt-crystallization in crystallization rate under isothermal crystallization conditions. The crystallinity of ET70 (EG content: 52.7 %) and ET80 (EG content: 65.9 %) were 20.27 % and 10.53 %, respectively. The minimum cold-crystallization melting temperature, the equilibrium melting temperature, and the crystallization rate occurred in ET70. The characteristic bands of PET trans conformation and PTT gauche conformation were observed in ET80 (EG content: 65.9 %). It was suggested that the crystal structure was difficult to form in ET80. The minimum crystallinity therefore occurred in ET80.
Tung, Chia-Hsin, and 董佳欣. "Structures of Poly(ethylene/trimethylene terephthalate) and Poly(ethylene/butylene terephthalate) Copolyesters Under Isothermal Crystallization Conditions." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14269927851373312210.
Full text逢甲大學
紡織工程所
95
This study focused on the crystal structure, morphology and melting behaviors of a series of copolyesters, which were synthesized using dimethyl terephthalate / ethylene glycol / 1,3-propanediol and dimethyl terephthalate / ethylene glycol / 1,4-butanediol with varying copolymerization ratios. The isothermal crystallization structure and crystallinity was studied using a wide angle x-ray diffractometer (WAXD). The morphological structure was probed using a small angle x-ray scattering (SAXS). Melting enthalpy and melting point temperature were measured using a differential scanning calorimeter (DSC). The WAXD deconvolution results showed that the major constitutional repeating unit in the molecular chain dominates the crystal structure as a host crystal. After isothermal crystallization, it was noted that the number and the intensity of crystal reflection peaks were both increased, especially more in ET70 and EB70. The minimum crystallinity occurred in ET80 (EG/PDO:66.6/33.5) and EB80 (EG/BDO:65.7/34.3). The small angle x-ray scattering profiles of deconvolution showed that the minimum crystal lamellar thickness and linear crystallinity for ET and EB copolyesters correspond to ET70 and EB80, respectively. Multiple melting behaviors in DSC heating trace were found. The minimum melting enthalpy values were found in ET80 and EB80. The minimum melting point temperature occurred in ET70 and EB70.
Pandey, Vijai B. "Adsorption column studies to predict the flow of nutrients through heterogenous porous media under equilibrium and isothermal conditions." 2012. https://scholarworks.umass.edu/dissertations/AAI3536052.
Full textLi, Hsien-Yi, and 李峴禕. "Simulation of two-phase metallurgical flows in isothermal condition." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/36885647717516255102.
Full text中原大學
土木工程研究所
100
This research studied the two-phase flow models to investigate the metallurgical flows phenomena in isothermal condition. The least-square finite element method (LSFEM) is adopted for the numerical simulation of the three-dimensional incompressible fluid represented by conservation form of mass and momentum equations. For a complete description of the free-surface motion, a volume of fluid (VOF) method with fixed Euler inertia coordinate is adopted. “Color function” is expressed by a continuous function to express the interface of two-phase fluid. This paper simulates the metallurgical flows in isothermal condition of four different setups. First the simulation of tapping phenomena in ferro-alloy furnaces and is compared with numerical simulation of Johansen (2002) in 2-D phenomena, next the three-dimensional dam break the metallurgical flows in isothermal condition will be compared with experimental data of Martin J. C. and Moyce W. J. (1952) also with numerical simulation of water dam break. The same as above setup, the third case is about a long cylindrical body set in the channel to observe the metallurgical flows, free surface variations after the collision of flow on the cylinder. Simulation of three-dimensional spherical liquid drop deformation under the influence of gravity is the last case, changes in wave position in front of the metallurgical droplet at different times is presented by assuming that the bottom of the model with free slip or no slip boundary conditions, respectively. From these cases, we can apply the three-dimensional model in the simulation of metallurgical flows.
Wu, Wen-Jui, and 吳文瑞. "Stress Analysis and Design Optimization of Angled Circular Pressurized Tube Under a Non-Isothermal Condition." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89817395045366612585.
Full text大葉大學
機械工程研究所碩士在職專班
97
Pressure tubes are used in various industries to transport high temperature steam, gas, liquid, and other fluids. Some components are usually required in pressurized tubing systems to relieve the high stress due to thermal expansion. Among them, U-tube is a kind which plays an important role. It is mainly serves as reinforcement and connection usage. In this study, the structural behavior of a non-isothermal U-tube under its simulated operating condition is investigated based on finite element analysis in conjunction with heat transfer and fluid mechanics theories. The investigation includes the structural stress analysis, temperature distribution analysis, the modal analysis, as well as the design optimization. A program based on the use of ANSYS is then provided for the users to select the optimal thickness of a U-tube under a safe operating condition.
Hsu, Jen-Che, and 許人哲. "Crystallization Behavior and Morphological Structure of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) - Poly(ε-caprolactone) Block Copolymers Under Isothermal Condition." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/56977828281621170815.
Full text逢甲大學
纖維與複合材料學系
100
This study focused on the morphology and melting behaviors of copolyester, which were synthesized from Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(ε-caprolactone) with 60 weight percent of PCL. The melting behaviors were studied by a differential scanning calorimeter (DSC). The conformation were investigated by In-situ Fourier transform infrared spectrometer (In-situ FTIR) The crystal morphology were observed by using hot stage polarizing microscope (HSPM). The morphological structure were probed by small angle x-ray scattering (SAXS). DSC showed that the melting enthalpy of PCL block decreased with the increase of temperature under isothermal conditions. When the temperature was over 45 ℃, the melting peak disappeared. FTIR showed that PHBV crystallized first at 60 ℃ and PCL crystals happened later at 36 °C from the melt. It could be concluded that PHBV crystallized at higher temperature and PCL crystallized at lower temperature. Based on HSPM and SAXS results, It showed that PCL block might exist in the confinement of PHBV lamellae at 35 ℃. When the temperature increased to 80 ℃, the long period increased with the interlamellae of melted PCL. The structure formed a lamellar morphology with crystalline and amorphous layers.
Barnette, Anna Lorraine Kim Seong H. "Adsorption isotherm and average orientation of adsorbed alcohol and water layers on SiO2 in ambient conditions." 2008. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-2971/index.html.
Full textAguilar, Patrícia Pereira. "Understanding the interaction between pDNA and anion exchange supports under linear and overloaded chromatographic conditions." Master's thesis, 2014. http://hdl.handle.net/10400.6/5553.
Full textThe potential of plasmid DNA as a therapeutic molecule in the cure of several diseases has been sustained by innumerous studies. The use of pDNA in therapies (DNA Vaccines and Gene Therapy) requires its production at the gram scale, with high purity levels and in an economic way, always taking into account the guidelines from the regulatory agencies. Anion-exchange chromatography have been successfully used in pDNA purification. Nevertheless, the mechanism of pDNA separation using this technique is still not completely understood. Additionally, due to economic reasons, it may be interesting to run the chromatographic processes in the overloaded mode. However, the overloaded mode is considerably more complex than linear chromatography, and suitable models do not exist. Thus, the prediction of separation behavior is generally unreliable, being a major impediment in the design and implementation of scaled-up units. Therefore, a better understanding of the mechanisms underlying non-linear chromatography of biomolecules has considerable practical interest. Flow Microcalorimetry (FMC) has proven its ability to provide an improved understanding of the driving forces, mechanisms and kinetics involved in the adsorption process of biomolecules onto several chromatographic systems. Thus, using FMC as a central technique, this study aims to understand the adsorption mechanism of pDNA (pVAX1-LacZ) onto the anion-exchange support Fast Flow Q-sepharose, considering linear and overloaded conditions and showing the role of nonspecific effects at the adsorptive process. Static binding capacity, Isothermal Titration Microcalorimetry (ITM) and fast performance chromatography were also accomplished to obtain a better understanding of the adsorption mechanism. Static binding capacity studies revealed that the mechanism of pDNA adsorption onto Q-sepharose follows a Langmuir-type isotherm profile. FMC experiments were performed in the linear, transition and overloaded zones of the isotherm, through a pulse injection or a continuous feed. All obtained thermograms comprised a first endothermic peak followed by an exothermic peak which, in some cases (volume overloading), resulted from overlapped peaks. Endothermic heat major contributor was suggested to be the desolvation process. Exothermic heats were related to the interaction between pDNA and Q-sepharose primary and secondary adsorption. Furthermore, FMC revealed that the overall adsorption process is exothermic, as expected for an anion-exchange interaction. Nevertheless, there are evidences of the presence of nonspecific effects, such as reorientation and electrostatic repulsive forces.