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1
Forbes, Graeme Alexander. "The practical application of an enhanced conveyance calculation in flood prediction." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/3319/.
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An enhanced one-dimensional mathematical model for simulating flood levels and calculating stage-discharge relationships is presented. Enhanced conveyance subroutines have been developed and incorporated into the commercially available river modelling software ISIS. The newly developed software has been verified using experimental and field data. When a river overtops its banks there is a vigorous interaction between slow moving flood plain flow and faster moving main channel flow. This interaction mechanism has been the focus of intense research over the past forty years. A selective review of this research is detailed with particular attention to the case of meandering channels. The Ackers Method and the James and Wark Method are two discharge capacity methods that have emanated from this recent research and are considered to be the most practically suitable methods and are indeed recommended by the Environment Agency of England and Wales. The methods account for interaction effects when flow is overbank in a straight and meandering channel respectively. It is these methods that have been incorporated into the commercially available and industry leading one-dimensional river model ISIS to enable an enhanced conveyance calculation. The newly developed software has been tested against the Flood Channel Facility Series A and B experiments to a satisfactory level of accuracy. The testing included predicted of stage discharge relationships and water level prediction. In addition it has been applied to the River Dane in Cheshire which is highly meandering and suited to the James and Wark methodology. This was intended to give practical advice concerning the use of the James and Wark Method and the degree of accuracy in estimating the 'channel parameters' which are required by this method. The results of this work showed that a significant rise in water level prediction is obtained when using the enhanced code. Also, it was clear that a high degree of accuracy was not required in estimating the 'channel parameters' with the possible exception of the sinuosity term.
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Locuniak, Maria N. "Early predictors of calculation fluency in second grade." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 177 p, 2010. http://proquest.umi.com/pqdweb?did=1992513281&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Soufflet, Yves. "Improvement of runback water film calculation and its impact on ice prediction." Thesis, Cranfield University, 2008. http://hdl.handle.net/1826/3786.
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Over the past few decades, aircraft icing has been the subject of numerous studies. Ice
accretion on an aircraft can damage its aerodynamic performance. It can also have a devastating
affect on structures such as high voltage pylons. The simulation of ice accretion
represents an important technological breakthrough in the understanding of ice behaviour
as well as an alternative to expensive experiments. Although numerical models will probably
never replace wind tunnel experiments, they continuously progress and benefit from
the latest advances in computing techniques. ICECREMO2 is a new generation model
and uses an unstructured grid approach. Unstructured meshes offer real advantages in
the generation of complex grid structures but also provide support for grid adaptivity.
Adaptivity consists in improving the resolution only in some aspects of the solution. It
offers the benefits of the high resolution without the computational overhead of classical
structured methods. Adaptive methods are usually more difficult to implement and the
application to the equation coupling water film and ice growth has never been investigated
before this work.
The mathematical model used in ICECREMO describes both the water film
flow and the
ice growth. This allows us to better predict glaze ice accretion when a runback water
film is present. The equation describing the thin film water
flow is a complex non-linear
fourth-order degenerate partial differential equation. To resolve complex features such
as a moving front, high resolution numerical methods are necessary. Such a numerical
scheme has been developed for this equation in a previous study on structured grid, and
has proven to be reliable. In this work Sweby's scheme has been reformulated in a finite
volume framework, an error estimator has been de ned for our adaptive mesh refinement
method and a grid refinement strategy has been implemented which follows the water film
front and keeps it under high resolution.
Finally, the impact of the improved resolution of the water film on the glaze ice growth
is investigated. Results obtained with first-order and high resolution methods have been
compared on different model problems under various conditions. At the end an extension
of the refinement strategy is proposed by defining error estimators with respect to the ice
layer and by combining it with a multi-step procedure.
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Hescock, Joshua. "CALCULATION OF THE EDGE EFFECT OFFSET FOR HIGH EXTRACTION COAL PANELS." UKnowledge, 2017. http://uknowledge.uky.edu/mng_etds/36.
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The Surface Deformation Prediction System (SDPS) program has been developed as an engineering tool for the prediction of subsidence deformation indices through the implementation of an influence function. SDPS provides reliable predictions of mining induced surface displacements, strains, and tilt for varying surface topography. One of the key aspects in obtaining reliable ground deformation prediction is the determination of the edge effect offset. The value assigned to the edge effect corresponds to a virtual offsetting of boundary lines delineating the extracted panel to allow for roof cantilevering over the mined out area.
The objective of this thesis is to describe the methods implemented in updating the edge effect offset algorithm within SDPS. Using known geometric equations, the newly developed algorithm provides a more robust calculation of the offset boundary line of the extracted panel for simplistic and complex mining geometries. Assuming that an extracted panel is represented by a closed polyline, the new edge offset algorithm calculates a polyline offset into the extracted panel by the user defined edge effect offset distance. Surface deformations are then calculated using this adjusted panel geometry. The MATLAB® program was utilized for development and testing of the new edge effect offset feature.
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Aikio, Englund Rebecca. "A study of calculation models for fatigue life prediction : A thesis accomplished together with GKN Aerospace." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-67741.
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GKN Aerospace in Trollhättan don’t use the latest ANSYS version and need to upgrade their life analysis models. The aim with this thesis is to do a study of the new models and investigate the times required for the calculations. A flight mission were chosen and this mission together with different life analysis models were run in the GKN in house program Life Analysis System. The results were analyzed and depending on the results additional runs were made or the problem were sent to the life management group at GKN Aerospace. Strain levels versus time were also plotted for the runs with the new models to get a perception where any problems occurs. The results from the model 4.10.149 had no variations between equal runs for the high pressure turbine and the low pressure turbine but there was a variation between the results when equal runs was made with the high pressure compressor. The results from model 4.10.157 and 4.10.124 and 4.10.160 and 4.10.173 had variations in the fatigue life for equal runs. The variations can depend on that the calculations converges to different solutions, the reason for this can depend on the non-linear contact elements. The variation in the results between equal runs occurs when the model uses two or more cores. The time required for the calculation becomes faster with the use of more cores. The longest duration had model 4.10.173 because of the many requirements for the calculations in this model. The problem with the variation in the results is sent to ANSYS.
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Lv, Duchao. "A Multi-Scale Simulation Approach to Deformation Mechanism Prediction in Superalloys." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469009668.
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Shi, Jingming. "Ab initio prediction of crystalline phases and their electronic properties : from ambient to extreme pressures." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1110/document.
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Dans cette thèse nous utilisons des méthodes globaux de prédiction des structures cristallographiques combinés à des techniques de grande capacité de traitement de données afin de prédire la structure cristalline de différents systèmes et dans des conditions thermodynamiques variées. Nous avons réalisé des prédictions structurales utilisant l'analyse cristalline par optimisation par essaims particuliers (CALYPSO) combinés avec la Théorie Fonctionnel de la Densité (DFT) ce qui a permis de mettre en évidence la stabilité de plusieurs composés jusqu'à la inconnus dans le digramme de phases du système Ba-Si et dans le système N-H-O. Nous avons également réalisé une étude à haute capacité de traitement de données sur un système ternaire de composition ABX2. Nous avons utilisé la Théorie Fonctionnel de la Densité combinant calculs de prototypes structuraux à partir des prédictions structurelles avec la méthode. Dans les paragraphes suivants nous résumons le contenu de différents chapitres de cette thèse. Le premier chapitre qui constitue une brève introduction au travail de cette thèse est suivi du chapitre 2 présentant les aspects théoriques utilisés dans ce travail. D'abord il est fait une brève introduction à la Théorie Fonctionnel de la Densité. A continuation nous décrivons quelques fonctions d'échange-corrélation choisies qui constituent des approximations rendant l'utilisation de la DFT efficace. Ensuite nous présentons différents procédés de prédiction structurale, et en particulier les algorithmes d'optimisation par essaims particuliers et de « Minima Hopping » qeu nous avons utilisés dans cette thèse. Finalement il est discuté comment doit-on se prendre pour évaluer la stabilité thermodynamique des nouvelles phases identifiées. Dans le chapitre 3, nous considérons le système Ba-Si. A travers l'utilisation d'une recherche structurale non-biaisée basée sur l'algorithme d'optimisation par essaims particuliers combinée avec des calculs DFT, nous faisons une étude systématique de la stabilité des phases et de la diversité structurale du système binaire Ba-Si sous haute pression. Le diagramme de phases résultant est assez complexe avec plusieurs compositions se stabilisant et se déstabilisant en fonction de la pression. En particulier, nous avons identifié des nouvelles phases de stœchiométrie BaSi, BaSi2, BaSi3 et BaSi5 qui devraient pouvoir être synthétisées expérimentalement dans un domaine de pressions étendu. Dans le chapitre 4 est présentée notre étude du diagramme de phases du système N-H-O. S'appuyant sur une recherche structural «évolutive » de type ab initio, nous prédisons deux nouvelles phases du système ternaire N-H-O qui sont NOH4 et HNO3 à de pressions allant jusqu'à 150 GPa. La nouvelle phase de NOH4 est stable entre 71 et 150 GPa, tandis que HNO3 est stable entre 39 et 150 GPa (la pression maximum de cette étude). Ces deux nouvelles phases sont lamellaires. Nous confirmons également que la composition NOH5 perd son stabilité pour des pressions supérieures à 122 GPa se décomposant en NH3 et H2O à cette pression. Le chapitre 5 se focalise sur les électrodes transparentes de type-p à base des chalcogénures ternaires. Nous utilisons une approche à grande capacité de traitement de données basée sur la DFT pour obtenir la delafossite et d'autres phases voisines de composition ABX2. Nous trouvons 79 systèmes qui sont absents de la base de données « Materials project database », qui sont stables du point de vue thermodynamique et qui cristallisent soit dans la structure delafossite, soit dans des structures très proches. Cette caractérisation révèle une grande diversité de propriétés allant depuis les métaux ordinaires aux métaux magnétiques et permettant d'identifier quelques candidats pour des électrodes transparents de type-p. Nous présentons enfin à la fin du manuscrit nos conclusions générales et les perspectives de ce travailIn this thesis we use global structural prediction methods (Particle Swarm Optimization and Minima Hopping Method) and high-throughput techniques to predict crystal structures of different systems under different conditions. We performed structural prediction by using the Crystal structure Analysis by Particle Swarm Optimization (CALYPSO) combined with Density Functional Theory (DFT) that made possible to unveil several stable compounds, so far unknown, on the phase diagrams of Ba-Si systerm and N-H-O system. Afterwards, we performed a high-throughput investigation on ternary compounds of composition ABX2, where A and B are elements of the periodic table up to Bi, and X is a chalcogen (O, S, Se, and Te) by using density functional theory and combining calculations of crystal prototypes with structural prediction (Minima Hopping Method). The following paragraphs summarize the content by chapter of this document. Chapter 1 is a short introduction of this thesis. Chapter 2 consists of the basic theory used in this thesis. Firstly, a short introduction of Density Function Theory (DFT) is presented. Then, we describe some approximate exchange- correlation functions that make DFT practical. Next, we introduce different structural prediction algorithms, especially Particle Swarm Optimization and Minima Hopping Method which we used in this thesis. Finally, we discuss the thermodynamic stablility criteria for a new a new structure. In Chapter 3, we first consider Ba–Si system. Using an unbiased structural search based on a particle-swarm optimization algorithm combined with DFT calculations, we investigate systematically the ground-state phase stability and structural diversity of Ba–Si binaries under high pressure. The phase diagram turns out to be quite intricate, with several compositions stabilizing/destabilizing as a function of pressure. In particular, we identify novel phases of BaSi, BaSi2, BaSi3, and BaSi5 that might be synthesizable experimentally over a wide range of pressures. Chapter 4 contains the investigation of the phases diagram of the N–H–O system. By using ab initio evolutionary structural search, we report the prediction of two novel phases of the N–H–O ternary system, namely NOH4 and HNO3 (nitric acid) at pressure up to 150 GPa. Our calculations show that the new C2/m phase of NOH4 is stable under a large range of pressure from 71 GPa to 150 GPa while the P21/m phase of HNO3 (nitric acid) is stable from 39 GPa to 150 GPa (the maximum pressure which we have studied). We also confirmed that the composition NOH5 (NH3H2O) becomes unstable for pressures above 122 GPa. It decomposes into NH3 and H2O at this pressure. Chapter 5 focuses on p-type transparent electrodes of ternary chalcogenides. We use a high-throughput approach based on DFT to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest- energy crystal structure. We find 79 systems not present in the "Materials project database" that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes. At the end of the thesis, we give our general conclusion and an outlook
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Mylona, Eugenia. "From global to local spatial models for improving prediction of urinary toxicity following prostate cancer radiotherapy." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S109.
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La radiothérapie externe est un traitement locorégional du cancer. L’objectif de la radiothérapie impose un compromis entre la délivrance d’une dose maximale dans la tumeur afin d’augmenter le contrôle local et la curabilité, et d’une dose minimale aux organes sains afin de limiter la toxicité. Les symptômes urinaires peuvent être liés à l’irradiation de régions spécifiques de la vessie ou de l'urètre. Dans ce cas, la dose reçue par l'ensemble de la vessie peut ne pas suffire à expliquer la toxicité urinaire. Dans le contexte du traitement du cancer de la prostate par radiothérapie, ce travail de thèse vise à analyser les corrélations spatiales entre la dose et les effets secondaires, cette problématique étant abordée dans un cadre d'analyse de population. Pour évaluer la contribution de l'urètre à la toxicité urinaire, nous proposons une méthode de segmentation basée sur plusieurs atlas pour identifier avec précision cette structure sur les images CT. Nous utilisons ensuite deux méthodes pour analyser la distribution de dose spatiale. L'une basée sur la construction de cartes 2D dose-surface (DSM) couplée à des comparaisons pixel par pixel et l'autre basée sur des cartes 3D dose-volume (DVM) combinées à des comparaisons par voxel. Les sous-régions identifiées ont été validées dans des populations externes, ouvrant la perspective d'une planification de traitement spécifique du patient. Nous étudions également le potentiel d'une amélioration complémentaire de la prédiction en exploitant de méthodes d'apprentissage automatiqueExternal beam radiotherapy (EBRT) is a clinical standard for treating prostate cancer. The objective of EBRT is to deliver a high radiation dose to the tumor to maximize the probability of local control while sparing the neighboring organs (mainly the rectum and the bladder) in order to minimize the risk of complications. Developing reliable predictive models of genitourinary (GU) toxicity is of paramount importance to prevent radiation-induced side-effects, and improve treatment reliability. Urinary symptoms may be linked to the irradiation of specific regions of the bladder or the urethra, in which case the dose received by the entire bladder may not be sufficient to explain GU toxicity. Going beyond the global, whole-organ-based models towards more local, sub-organ approaches, this thesis aims to improve our understanding of radiation-induced urinary side-effects and ameliorate the prediction of urinary toxicity following prostate cancer radiotherapy. With the objective to assess the contribution of urethra damage to urinary toxicity, we propose a multi-atlas-based segmentation method to accurately identify this structure on CT images. The second objective is to identify specific symptom-related subregions in the bladder and the urethra predictive of different urinary symptoms. For this purpose, we propose two methodologies for analyzing the spatial dose distribution; one based on the construction of 2D dose-surface maps (DSM) coupled with pixel wise comparisons and another based on 3D dosevolume maps (DVMs) combined with voxel-wise comparisons. Identified subregions are validated in external populations, opening the perspective for patient specific treatment planning. We also implement and compare different machine learning strategies and data augmentation techniques, paving the way to further improve urinary toxicity prediction. We open the perspective of patient-specific treatment planning with reduced risk of complications
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Tiltu, Klintborg Anna. "BCR-ABL1A TYROSINE KINASE ASSOCIATED WITH CHRONIC MYELOID LEUKEMIA : Calculation of solvation energiesand electrostatics by APBS and prediction of 2D and 3D structureby homology protein modeling." Thesis, Umeå universitet, Institutionen för integrativ medicinsk biologi (IMB), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-182126.
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Svensson, Markus. "Modeling Pavement Performance based on Data from the Swedish LTPP Database : Predicting Cracking and Rutting." Licentiate thesis, KTH, Väg- och banteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119863.
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The roads in our society are in a state of constant degradation. The reasons for this are many, and therefore constructed to have a certain lifetime before being reconstructed. To minimize the cost of maintaining the important transport road network high quality prediction models are needed. This report presents new models for flexible pavement structures for initiation and propagation of fatigue cracks in the bound layers and rutting for the whole structure. The models are based on observations from the Swedish Long Term Pavement Performance (LTPP) database. The intention is to use them for planning maintenance as part of a pavement management system (PMS). A statistical approach is used for the modeling, where both cracking and rutting are related to traffic data, climate conditions, and the subgrade characteristics as well as the pavement structure.QC 20130325
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Romero, Alejandro Antonio. "Phase-splitting prediction in isothermal flash calculations." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27996.
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The development of processes that operate at conditions where multiple fluid-phase equilibria may occur demands fast and reliable simulation algorithms. The success of these algorithms depends on the correct prediction of the number and compositions of the phases present at a given temperature, pressure and overall fluid composition. The most commonly used routine for this purpose is the isothermal (single-stage) flash calculation.
A robust and efficient method to predict phase-splitting previous to performing an isothermal flash is implemented in this work. It is based on the thermodynamic stability analysis of the source phase using a Gibbs energy tangent-plane criterion. Depending on the outcome of the phase-split tests, the system may be declared stable as a single phase and thus no further calculations are needed, or unstable in which case a potential two- or three-phase solution can be obtained. Only in this last instance would the corresponding flash calculation follow, depending on the nature and quantity of the phases found: a vapour-liquid (VL) or a liquid- liquid (LL) flash if two phases are predicted, or a multiphase flash (VLL) when three phases are expected.
In addition to readily recognizing the number and type of phases present, the stability tests provide excellent initial composition estimates for the flash which assure fast convergence to the stable solution. Even though the algorithms developed can be used with any suitable model to calculate equilibrium properties, cubic equations of state are used throughout in this work as a single model to describe all fluid phases.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Táborský, Miroslav. "Výpočtová predikce charakteristických parametrů procesu spalování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230294.
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The present thesis is focused on calculation prediction of characteristic parameters of combustion process in combustion chamber which is installed at burners testing laboratory. In the thesis basic theoretical knowledge needed for description of heat transfer in process combustion equipment are given. The Plug Flow Furnace Model is based on this knowledge. This model is used to evaluation of specific heat flux in tube furnaces. In the next step the Plug – Flow model is modified and adapted on the combustion chamber. Obtained results are compared with a measured data. By this comparison quality of this model is assessed.
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Mersinligil, Mehmet. "Airfoil Boundary Layer Calculations Using Interactive Method And En Transition Prediction Technique." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607677/index.pdf.
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Boundary layer calculations are performed around an airfoil and its wake. Smith-van Ingen
transition prediction method is employed to find the transition from laminar to turbulent
flow. First, potential flow around the airfoil is solved with the Hess-Smith panel method.
The resulting velocity distribution is input to the boundary layer equations in order to find
a so called blowing velocity distribution. The output of the boundary layer equations are
also used to compute the location of onset of transition using the Smith-van Ingen en
transition prediction method. The obtained blowing velocity distribution is fed back to the
panel method to find a velocity distribution which includes the effects of viscosity. The
procedure described is repeated until convergence is observed. A computer program is
developed using the theory. Results obtained are in good accord with measurements
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Kumari, Vandana. "Structure-Based Computer Aided Drug Design and Analysis for Different Disease Targets." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1311612599.
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Keet, Fred. "New concepts for managing diabetes mellitus / Fred Keet." Thesis, North-West University, 2003. http://hdl.handle.net/10394/9612.
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Preface -
Biotechnology is generally considered to be the wave of the future. To facilitate
accurate and rapid development of medication and treatments, it is critical that we are
able to simulate the human body. One section of this complex model would be the
human energy system.
Pharmaceutical companies are currently pouring vast amounts of capital into research
regarding general simulation of cellular structures, protein structures and bodily
processes. Their aim is to develop treatments and medication for major diseases.
Some of these diseases are epidemics like cancer, cardiovascular diseases, stress,
obesity, etc. One of the most important causes of these diseases is poor blood glucose
control.
Current management methods for insulin dependent diabetes are limited to trial and
error systems: clearly ineffective and prone to errors. It is critical that better
management systems be developed, to ease the diabetic epidemic.
The blood glucose control system is one of the major systems in the body, as we are
in constant need of energy to facilitate the optimum functioning of the human body.
This study makes use of a developed simulation model for the human energy system
to ease the management of Diabetes mellitus, which is a malfunction of the human
energy system.
This dissertation is presented in two parts: The first part discusses the human energy
simulation model, and the verification thereof, while the second presents possible
applications of this model to ease the management of Diabetes.
The human energy system simulation model -
This section discusses the development and verification of the model. It also touches
on the causes, and current methods, of managing diabetes, as well as the functioning
of the human energy system.
The human energy model is approached with the conservation of energy in mind. A
top down model is developed, using data from independent studies to verify the
model.
Application of human energy simulation model -
The human energy simulation model is of little use if the intended audience cannot
use it: people suffering from malfunctioning energy systems. These include people
having trouble with obesity, diabetes, cardiovascular disease, etc. To facilitate this, we
need to provide a variety of products useable by this group of people.
We propose a variety of ways in which the model can be used: Cellular phone
applications, Personal digital assistants (PDAs) applications, as well as computer
software.
By making use of current technology, we generate a basic proof-of-concept
application to demonstrate the intended functionality.MIng (Mechanical Engineering) North-West University, Potchefstroom Campus, 2004
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Rocklin, Gabriel Jacob. "Predicting charged protein-ligand binding affinities using free energy calculations." Thesis, University of California, San Francisco, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3587895.
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Predicting protein-ligand binding free energy from physical principles is a grand challenge in biophysics, with particular importance for drug discovery. Free energy calculations compute binding affinities by using classical mechanics to model the protein and ligand at atomic resolution, and using statistical mechanics to analyze simulations of these models. The binding affinities computed from these simulations are fully rigorous and thermodynamically correct for the model (with adequate sampling), and will agree with experimentally measured binding affinities if the model is accurate. Because free energy calculations capture the full statistical complexity of binding for flexible molecules at ambient temperature, they offer the greatest potential for quantitative accuracy of any physical method for predicting binding.
Here, I (& coauthors) present several studies relating to using free energy calculations to predict protein-ligand binding affinities for charged compounds. First, we introduce the Separated Topologies method, an approach for using free energy calculations to predict relative binding affinities of unrelated ligands. This method is useful for studying charged compounds because charged compounds are very difficult to study using absolute binding calculations, increasing the importance of relative binding calculations. Second, we use free energy calculations to predict absolute binding affinities for charged molecules to a simplified protein binding site, which is specially designed for studying charged interactions. These predictions are compared to new experimental affinity measurements and new high-resolution structures of the protein-ligand complexes. We find that all affinities are predicted to be too strong, and that this error is directly correlated with the polarity of each ligand. By uniformly weakening the strength of electrostatic interactions, we are more successful at predicting binding affinity. Third, we design and validate an analytical correction scheme to correct binding free energy calculations of ions for artifacts caused by the periodic boundary conditions employed in simulations. Fourth, we examine the sensitivity of binding affinities from free energy calculations to the force field parameters used in the simulations. This provides insight into the strength of electrostatic interactions in protein simulations, complementing our previous work comparing simulation results to experiments. Finally, we discuss potential future directions of this work.
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Neumann, M. A., Frank J. J. Leusen, and John Kendrick. "A major advance in crystal structure prediction." Wiley, 2008. http://hdl.handle.net/10454/4740.
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noA crystal ball? A new method for crystal structure prediction combines a tailor-made force field with a density functional theory method incorporating a van der Waals correction for dispersive interactions. In a blind test, the method predicts the correct crystal structure for all four compounds, one of which is a cocrystal. The picture shows the predicted structure of one of the compounds in green and the experimental structure in blue.
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Cui, Jie. "Combining statistics and scattering calculations for improved predictions of molecular collision observables." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54351.
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This thesis describes four types of cold molecular collision systems with increasing complexity: from simple atom-diatomic molecule to complicated polyatomic molecule-polyatomic molecule. The early thesis work is concerned with three open questions pertaining to collision dynamics of cold molecules. We demonstrate the possibility of controlling collisional decoherence of ultracold molecules by tuning an external magnetic field. We then provide insight into the feasibility of evaporative cooling of molecules, and for the first time incorporate the uncertainty analysis of the potential energy surface (PES) into scattering calculations. In addition, we use classical trajectory methods to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. The second half of the thesis work is focused on combining statistical methodology and scattering calculations to address two major problems in molecular dynamics calculations: increasing computational complexity and uncertainties due to inaccuracies of PES. Using a small number of scattering calculations, we show that we can build a Gaussian Process (GP) model to statistically approximate collision outcomes for complex molecules, and then perform the uncertainty analysis and the sensitivity analysis. We also demonstrate that trained by a combination of classical and quantum calculations, a GP model can provide an accurate description of the quantum scattering cross sections, even near scattering resonances.Science, Faculty of
Chemistry, Department of
Graduate
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Eaton, Jeffery P. "Analysis of the effects of dynamic characteristic dimension calculations on FLIR performance prediction models." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA331245.
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Gatsiou, Christina-Anna. "Improving the accuracy of lattice energy calculations in crystal structure prediction using experimental data." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/34685.
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Crystal structure prediction (CSP) has been a problem of great industrial interest but also a fundamental challenge in condensed matter science. The problem involves the identification of the stable and metastable crystals of a given compound at certain temperature and pressure conditions. Computational CSP methods based on the lattice energy minimization have been successful in identifying experimentally observed crystals of an organic compound as local minima of the lattice energy landscape but not always with the correct relative stability. This is primarily controlled by the lattice energy model. The lattice energy model adopted in this work is based on the assumption that molecules are rigid, electrostatic interactions are modelled via distributed multipoles derived from the ab initio charge density of the gas phase conformation and an empirical pairwise exp-6 potential for the repulsion dispersion interactions. Based on the fact that the reliability of all computational models is based on their agreement with experimental evidence, the use of available experimental data for improving the lattice energy model is the main focus of this work. First the impact of different modelling choices -- choice of level of theory for electrostatics and parameters for the repulsion-dispersion term -- in the modelling of experimental structures, energies and relative stabilities is investigated. Results suggest that a reestimation of the repulsion-dispersion parameters is expected to produce parameters consistent with changes in the other lattice energy terms and bring the model closer to experiment, consequently improving predictions. An algorithm, CrystalEstimator, for fitting the exp-6 potential parameters by minimizing the sum of squared deviations between experimental structures and energies and the corresponding relaxed structures and energies is developed. The lattice energy of the experimental structures is minimized by the program DMACRYS. The solution algorithm is based on the search of the parameter space using deterministic low discrepancy sequences; and the use of an efficient local minimization algorithm. The proposed method is applied to derive transferable exp-6 potential parameters for hydrocarbons, organosulphur compounds, azahydrocarbons, oxohydrocarbons and organosulphur compounds containing nitrogen. Three different sets of parameters are developed, suitable for use in conjunction with three different models of electrostatics derived at the HF/6-31G(d,p), M06/6-31G(d,p) and MP2/6-31g(d,p) levels. A good fit is achieved for all the new sets of parameters with a mean absolute error in sublimation enthalpies less than 3.5 kJ/mol and an average rmsd15 less than 0.35 Å. Prediction studies are performed for acetylene, tetracyanoethylene and blind test molecule XXII and the generated lattice energy landscapes are refined with the new models. The observed experimental structures are predicted with better structural agreement but the same or higher ranking than those obtained by the previously used FIT parameter set.
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Reid, Jolene Patricia. "Development and application of computational methods for the prediction of chiral phosphoric acid catalyst performance." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/269024.
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Chiral phosphoric acids are bifunctional catalysts that have the ability to activate electrophiles and nucleophiles through hydrogen bonding, and they have been successful in catalysing highly enantioselective additions of a wide range of nucleophiles to imines. In most literature reports it is not frequently revealed how these catalysts impart enantioselectivity. Thus, the vast majority of time required for reaction development is expended on the optimisation of the catalyst features. The research described here explores the ability of relating computational derived catalyst parameters to enantioselectivity as a means to assess the catalyst features important for enantioinduction. The proposed features are evaluated computationally and summarised into simple qualitative models to understand and predict outcomes of similar reactions. In Chapter 1, I provide an overview of the progress and challenges in the development of chiral phosphoric acid mediated reactions. I highlight leading computational studies that have enabled a greater understanding of how the catalyst imparts reactivity and selectivity. In general, the studies focus on the most effective catalyst and do not do a detailed investigation into the effects of changing the substituents at the 3,3’ positions. Implicating steric effects from reasonably large groups as a key component in imparting enantioselectivity. However, it is clear that they have a more subtle effect. A large group is required but if it is too large poor or unusual results are obtained, making the correct choice of reaction conditions challenging. In Chapter 2, I develop a quantitative assessment of the substituents at the 3,3’ positions. I show in Chapters 3 and 4 that I can use rotation barriers in combination with a novel steric parameter, AREA(θ), to correlate enantioselectivity. By exploiting this finding, the catalyst features important for enantioselectivity can be identified, and this is validated by QM/MM hybrid calculations. Summarising these detailed calculations into a single qualitative model, guides optimal catalyst choice for all seventy-seven literature reactions reporting over 1000 transformations. These mechanistic studies have guided the design of a new catalyst with increased versatility, which is discussed in Chapter 5. Chapter 6 details my study into the effect of the hydroxyl group on the mechanism of transfer hydrogenation of imines derived from ortho-hydroxyacetophenone. I show, using detailed DFT and ONIOM calculations, that transition states of these reactions involve hydrogen bonding from both the hydroxyl group on the imine and the nucleophile’s proton to the phosphate catalyst. In Chapter 7, computational analysis is used to provide insight into the origins of enantioselectivity in chiral phosphoric acid catalysed Friedel-Crafts and Mannich reactions proceeding through monoactivation mechanisms. The final chapter contains an in-depth look into the stereoelectronic effects altering enantioselectivity in the silver-phosphate mediated spirocyclisation reaction involving aromatic ynones. In this study I show that enantioselectivity is governed by the non-covalent interactions between the aromatic group of the ynone and the 3,3’ substituent. I was able to propose synthetic modifications to the substrate used in this reaction, resulting in an improvement in enantioselectivity.
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Alhalasah, Wasim. "Electrochemical Materials Science: Calculation vs. Experiment as Predictive Tools in Tailoring Intrinsically Conducting Polythiophenes." Doctoral thesis, Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700375.
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Eine Reihe 3-(p-X-phenyl)-Thiophenmonomeren (X = -H, -CH3, -OCH3, -COCH3, -COOC2H5, -NO2) wurde elektrochemisch polymerisiert, um Filme zu erhalten, die umkehrbar reduziert und oxidiert werden konnten (n-und p-dotiert wurden). Die Oxidationspotentiale der Monomere und die formalen Potentiale der n und p-Dotierprozesse der Polymere wurden mit Resonanz- und induktiven Effekten der Substituenten (Hammett konstanten) am Phenylring sowie semiempirisch errechneten Bildungswärmen der Monomereradikalkationen korreliert. Außerdem wurden die Oxidationspotentiale mit den Ionisierungspotentialen der Monomere verglichen, die über die Dichtefunktionialtheorie (DFT) errechnet wurden, die der Energie für das Erzeugen der Radikalkationen entsprechen. Um theoretische Grundlagen für die Einstufen-Bildung regioregulär -konjungierter Oligo- und Polythiophene zu erhalten, wurden die elektronischen Zustände von 3-Phenylthiophen-Derivaten anhand von Molekülorbitalberechnungen auf Grundlage der Dichtefunktionaltheorie mit Becke’s Drei-Parameter-Funktion (B3LYP), sowie mit den Basissätzen 6-31G(d) und 3-21G(d) erklärt. Die Reaktivität der Verknüpfung von mono- und oligo-3-Phenylthiophenen wurde von den berechneten ungepaarten Elektronenspindichten der entsprechenden Radikal-Anionen abgeleitet. Die Ionisierungspotentiale, die den Energien zur Erzeugung der Radikal-Anionen während der Oxidation entsprechen, wurden abgeschätzt. Die aus den 3-Phenylthiophenen entstandenen regioselektiven Hauptprodukte können gut durch die Größe der Spindichten erklärt werden. Da die Verknüpfungsreaktion an der zwei-Position des Thiophnrings (C-2) sterisch durch die Phenylgruppe und den Thiophenring gehindert ist, startet die Initiierung der 3-Phenylthiophene über die Bildung eines Kopf-Schwanz-Dimers. Folglich spielt das Kopf-Schwanz-Dimer eine wichtige Rolle bei den Wachstumsreaktionen der 3-Phenylthiophene. Die Ursache dafür liegt darin, dass das Kopf-Schwanz-Dimer in 5-Position die höchste Spin-Dichte besitzt und die Wahrscheinlichkeit einer Kopf-Kopf-Verknüpfung aufgrund der sterischen Hinderung zwischen dem Thiophenring und der Phenylgruppe gering ist. Polymerfilme von 3-Phenylthiophenderivaten, die durch elektrochemische Polymerisation synthetisiert wurden, sind in situ und ex situ durch Resonanz-Raman-Spektroskopie bei verschiedenen Anregungswellenlängen, sowie durch in situ und ex situ UV-Vis Spektroskopie analysiert wurden. Die Entwicklung der in situ UV-Vis-Spektren der Polymer von 3-Phenylthiophene nach der Dotierung wird durch ähnliche Eigenschaften gekennzeichnet, wie für viele Polythiophene mit einem hohen Grad der Konjugation beobachtet. Während der schrittweisen Oxidation der Poly-3-phenylthiophen Filme verringert sich die Intensität der Absorption wegen des Überganges bei 450-566 nm und ein neues ausgedehntes Absorptionsband, das auf (bi)polaron Zustände bezogen wird erscheint bei ungefähr 730-890 nm. Andererseits wird während der Oxidation (p-Dotierung) des Poly3-phenylthiophen Filmes eine blau/hypsochrome Verschiebung für beide Absorptionsbänder beobachtet . Es wird durch die Tatsache erklärt, dass ein Polymer eine Verteilung der Kettenlängen enthält und die längste Polymer kette (dessen Absorption bei niedriger Energie auftritt), bei niedrigeren Potentialen zu oxidieren beginnt. Die elektrochemischen Bandlücken der Derivate von 3-Phenylthiophen sind durch zyklische Voltametrie gemessen worden. Der Effekt der Substituenten auf den Oxidations-/Reduktions- potentiale wird besprochen. Bei Bandlücken, die durch zyklische Voltammetrie erhalten wurden, hat sich herausgestellt, dass sie im Allgemeinen höher liegen als optische Bandlücken. Erste Resultate der in situ Resonanz-Raman-Spektroskopie, von dem elektrochemisch erzeugten Polymerderivate von 3-Phenylthiophen Filmen auf einer Platinelektrode, in einer organischen Elektrolytlösung, werden berichtet. Beobachtete Raman Banden werden zugewiesen; gegründet auf diesen Resultaten werden die zuvor angenommenen molekularen Strukturen diskutiertA series of 3-(p-X-phenyl) thiophene monomers (X= –H, –CH3, –OCH3, –COCH3, –COOC2H5, –NO2) was electrochemically polymerized to furnish polymer films that could be reversibly reduced and oxidized (n- and p-doped). The oxidation potentials of the monomers and formal potentials of the n- and p-doping processes of polymers were correlated with resonance and inductive effects (Hammett constants) of the substituents on the phenyl ring as well as the semiempirically calculated heats of formation of the monomer radical cations. Moreover, the oxidation potentials of the monomers were correlated with the ionization potentials of the monomers calculated via density functional theory (DFT), which correspond to the energies for generating radical cations during oxidative processes. For obtaining a theoretical basis for the one-step formation of regioregular –conjugated oligo-and polythiophenes, the electronic states of 3-phenylthiophene derivatives were elucidated by molecular orbital calculations using density functional theory with the Becke-type three parameters functional (B3LYP), the 6-31G(d), and 3-21G(d) basis sets. The reactivity for coupling reaction of mono- and oligo-3-phenylthiophenes are inferred from the calculated unpaired electron spin densities of the respective radical cations, and the ionization potentials which correspond to the energies for generating radical cations during oxidative processes were estimated. The major regioselective products of the oligomerization of 3-phenylthiophene can be well understood in terms of the magnitude of spin densities. Since the steric hindrance between the phenyl group and thiophene ring interferes with the coupling reaction occurring between 2-postions (C–2) of thiophene rings, the initiating reaction of 3-phenylthiophene is generaton of a head-to-tail (HT) dimer. Thus, the head-to-tail (HT) dimer plays an important role in the propagation reactions of 3-phenylthiophene. This originates from the highest spin density at the 5- position of the HT dimer and low probability of the HH coupling due to the steric hindrance between thiophene ring and phenyl group. Polymer films of the 3-phenylthiophene derivatives prepared by electrochemical polymerization were analyzed, in situ and ex situ, with resonance Raman spectroscopy using several excitation wavelengths as well as in situ and ex situ UV-Vis-spectroscopy. The evolution of the in situ UV-Vis-spectra of poly 3-phenylthiophene derivatives upon doping is characterized by similar features as observed for many polythiophenes with high degree of conjugation. During stepwise oxidation of the poly-3-phenylthiophene films the intensity of the absorption due to the transition around 450–566 nm decreases and a new broad absorption band related to (bi)polaron states appears around 730-890 nm. On the other hand, during the oxidation (p-doping) of the poly-3-phenylthiophene films a blue/hypsochromic shift is observed for both absorption bands. It is explained by the fact that a polymer contains a distribution of chain lengths, and the longest polymer chains (the absorption of which occurs at lower energies) start to oxidize at lower potentials. The electrochemical bandgaps of 3-phenylthiophene derivatives have been measured by cyclic voltammetry. The effect of substituents on the oxidation / reduction potentials is discussed. Bandgaps obtained by cyclic voltammetry have been found to be in general higher than optical bandgaps. Preliminary results of in situ resonance Raman spectroscopy of electrochemically generated poly-3-phenylthiophene derivatives films on a platinum electrode exposed to an organic electrolyte solution are reported. Observed Raman bands are assigned; based on these results previously suggested molecular structures are discussed
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Holm, Hannes. "A Framework and Calculation Engine for Modeling and Predicting the Cyber Security of Enterprise Architectures." Doctoral thesis, KTH, Industriella informations- och styrsystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-140525.
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Information Technology (IT) is a cornerstone of our modern society and essential for governments' management of public services, economic growth and national security. Consequently, it is of importance that IT systems are kept in a dependable and secure state. Unfortunately, as modern IT systems typically are composed of numerous interconnected components, including personnel and processes that use or support it (often referred to as an enterprise architecture), this is not a simple endeavor. To make matters worse, there are malicious actors who seek to exploit vulnerabilities in the enterprise architecture to conduct unauthorized activity within it. Various models have been proposed by academia and industry to identify and mitigate vulnerabilities in enterprise architectures, however, so far none has provided a sufficiently comprehensive scope. The contribution of this thesis is a modeling framework and calculation engine that can be used as support by enterprise decision makers in regard to cyber security matters, e.g., chief information security officers. In summary, the contribution can be used to model and analyze the vulnerability of enterprise architectures, and provide mitigation suggestions based on the resulting estimates. The contribution has been tested in real-world cases and has been validated on both a component level and system level; the results of these studies show that it is adequate in terms of supporting enterprise decision making. This thesis is a composite thesis of eight papers. Paper 1 describes a method and dataset that can be used to validate the contribution described in this thesis and models similar to it. Paper 2 presents what statistical distributions that are best fit for modeling the time required to compromise computer systems. Paper 3 describes estimates on the effort required to discover novel web application vulnerabilities. Paper 4 describes estimates on the possibility of circumventing web application firewalls. Paper 5 describes a study of the time required by an attacker to obtain critical vulnerabilities and exploits for compiled software. Paper 6 presents the effectiveness of seven commonly used automated network vulnerability scanners. Paper 7 describes the ability of the signature-based intrusion detection system Snort at detecting attacks that are more novel, or older than its rule set. Finally, paper 8 describes a tool that can be used to estimate the vulnerability of enterprise architectures; this tool is founded upon the results presented in papers 1-7.Informationsteknik (IT) är en grundsten i vårt moderna samhälle och grundläggande för staters hantering av samhällstjänster, ekonomisk tillväxt och nationell säkerhet. Det är därför av vikt att IT-system hålls i ett tillförlitligt och säkert tillstånd. Då moderna IT-system vanligen består av en mångfald av olika integrerade komponenter, inklusive människor och processer som nyttjar eller stödjer systemet (ofta benämnd organisationsövergripande arkitektur, eller enterprise architecture), är detta tyvärr ingen enkel uppgift. För att förvärra det hela så finns det även illvilliga aktörer som ämnar utnyttja sårbarheter i den organisationsövergripande arkitekturen för att utföra obehörig aktivitet inom den. Olika modeller har föreslagits av den akademiska världen och näringslivet för att identifiera samt behandla sårbarheter i organisationsövergripande arkitekturer, men det finns ännu ingen modell som är tillräckligt omfattande. Bidraget presenterat i denna avhandling är ett modelleringsramverk och en beräkningsmotor som kan användas som stöd av organisatoriska beslutsfattare med avseende på säkerhetsärenden. Sammanfattningsvis kan bidraget användas för att modellera och analysera sårbarheten av organisationsövergripande arkitekturer, samt ge förbättringsförslag baserat på dess uppskattningar. Bidraget har testats i fallstudier och validerats på både komponentnivå och systemnivå; resultaten från dessa studier visar att det är lämpligt för att stödja organisatoriskt beslutsfattande. Avhandlingen är en sammanläggningsavhandling med åtta artiklar. Artikel 1 beskriver en metod och ett dataset som kan användas för att validera avhandlingens bidrag och andra modeller likt detta. Artikel 2 presenterar vilka statistiska fördelningar som är bäst lämpade för att beskriva tiden som krävs för att kompromettera en dator. Artikel 3 beskriver uppskattningar av tiden som krävs för att upptäcka nya sårbarheter i webbapplikationer. Artikel 4 beskriver uppskattningar för möjligheten att kringgå webbapplikationsbrandväggar. Artikel 5 beskriver en studie av den tid som krävs för att en angripare skall kunna anskaffa kritiska sårbarheter och program för att utnyttja dessa för kompilerad programvara. Artikel 6 presenterar effektiviteten av sju vanligt nyttjade verktyg som används för att automatiskt identifiera sårbarheter i nätverk. Artikel 7 beskriver förmågan av det signatur-baserade intrångsdetekteringssystemet Snort att upptäcka attacker som är nyare, eller äldre, än dess regeluppsättning. Slutligen beskriver artikel 8 ett verktyg som kan användas för att uppskatta sårbarheten av organisationsövergripande arkitekturer; grunden för detta verktyg är de resultat som presenteras i artikel 1-7.
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Hassan, Abdihakim. "On the prediction of partition coefficients using the statistical associating fluid theory underpinned by quantum mechanical calculations." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44112.
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The thermodynamic modelling of phase equilibrium is of central importance in chemical engineering applications. The design, operation and develop- ment of new chemical processes is based to a large extent on the knowledge of the equilibrium that occurs between co-existing fluid phases. Where re- liable experimental data at required process conditions is unavailable, an understanding of the molecular description of condensed phase matter is key to predicting the thermodynamic properties of these fluid systems. To this end, numerous models and theories have been developed that seek to link microscopic intermolecular interactions with bulk macroscopic thermo- dynamic properties. In this thesis, two such constructs for the prediction of phase equilibrium are considered. The empirical linear solvation energy relationship (LSER) that relates specific/unspecific intermolecular interac- tions to infinite dilution solute properties, and equations of state (EoS) for the prediciton of vapour-liquid and liquid-liquid equilibrium. The LSER model utilises hydrogen bond acceptor/donor parameters (A and B) alongside polarisability (S), volume (V) and molar refraction (E) param- eters to describe various solute properties. In this study, the prediciton of solute infinite dilution partititon coefficient is of particular interest. While the V and E parameters can be obtained from molecular structure calcula- tions that account for the number of atoms and bonds in a molecule, the re- maining LSER parameters are usually derived from chromatographic experiments. However, successive studies have successfully correlated and pre- dicted the hydrogen bonding parameters from quantum mechanical (QM) calculated molecular properties, enabling the rapid calculation of infinite dilution solute properties in the so-called QM/LSER approach. In this the- sis, two independent linear regression relationships that relate theoretically calculated hydrogen bond stabilisation energies at a donor and/or acceptor site(s) to experimental hydrogen bonding ability of a solute molecule have been determined. Once obtained, the solute hydrogen bonding parameters are used in conjunction with dispersion and volume parameters in the LSER to obtain solute partition coefficients. Using this approach ,the octanol/wa- ter partition coefficients of various molecules have been estimated, of this, the absolute average error of a sub-set of straight chained, mono-functional solute molecules has been determined to be 23.04% when compared to ex- perimental data. The second approach to modeling condensed phased matter is based on the statistical associating fluid theory (SAFT), a molecular-based equation of state with a foundation in statistical mechanics. Here, a recently devel- oped group-contribution version i.e., SAFT-1 is considered. The SAFT-1 EoS has been successfully applied in the prediction of the octanol/water patition coefficients of a range of solute molecules that include n-alkane, n-alkene, 2- ketone and n-amine molecules. Where the average absolute error of SAFT- 1 predicitons when compared to experimental data is found to be 13.20%. However, as with other EoS, SAFT-1 is dependent on experimental data re- quired to parameterise the various groups that make up the fluid/fluid mix- ture under investigation. The aim of this work is to increase the predictive ability of SAFT-1 by reducing dependence on experimental data, whereby in- stead of equilibrium data, solute partition coefficients estimated using the QM/LSER method are used to parameterise the relevant molecular groups. In the final part of the thesis, the proposed hypothesis of combining the QM/LSER and SAFT-1 methods is tested with the aim of predicting the phase behaviour of binary mixtures. The method relies on the calculation of partition coefficients using QM and LSER, the calculated partition coef- ficients are then used to parameterise the unlike group-group interactions required for the prediction of binary mixture behaviour in SAFT-1. This methodology has been validated using the n-aldehyde and 2-ketone chemi- cal families, where using QM/LSER to parameterise SAFT-1 has been found to achieve results that are comparative to the classical empirical approach of parameterising the SAFT-1 EoS when predicting binary phase behaviour. The unlike group interaction parameters for the SAFT-1 EoS have been suc- cessfully parameterised using partition coefficient data estimated from the- oretically calculated quantum mechanical molecular properties. However, the solutes considered in this study are limited to linear mono-functional molecules. The reason for this limitation is two fold. Firstly, predicting hydrogen bond parameters of multi-functional molecules is unreliable mainly as a consequence of polarisation of H-bond sites due to the proximity of functional groups. Therefore a better understanding of how polarisation affects hydrogen bonding is required. Secondly, within SAFT-1 the major- ity of available groups are for modeling linear mono-functional molecules. However there is continuing work to model both branched and multifunc- tional molecules. Once both of these concerns are effectively dealt with, the proposed methodology can be used to characterize a wider range of SAFT- 1 groups and predict thermodynamic behaviour of molecules based on QM molecular calculations.
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Le, Joelle. "The calculation of physicochemical descriptors and their application in predicting properties of drugs and other compounds." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369105.
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Schönherr, Marek. "Improving predictions for collider observables by consistently combining fixed order calculations with resummed results in perturbation theory." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-83876.
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With the constantly increasing precision of experimental data acquired at the current collider experiments Tevatron and LHC the theoretical uncertainty on the prediction of multiparticle final states has to decrease accordingly in order to have meaningful tests of the underlying theories such as the Standard Model. A pure leading order calculation, defined in the perturbative expansion of said theory in the interaction constant, represents the classical limit to such a quantum field theory and was already found to be insufficient at past collider experiments, e.g. LEP or Hera. Such a leading order calculation can be systematically improved in various limits. If the typical scales of a process are large and the respective coupling constants are small, the inclusion of fixed-order higher-order corrections then yields quickly converging predictions with much reduced uncertainties. In certain regions of the phase space, still well within the perturbative regime of the underlying theory, a clear hierarchy of the inherent scales, however, leads to large logarithms occurring at every order in perturbation theory. In many cases these logarithms are universal and can be resummed to all orders leading to precise predictions in these limits. Multiparticle final states now exhibit both small and large scales, necessitating a description using both resummed and fixed-order results. This thesis presents the consistent combination of two such resummation schemes with fixed-order results. The main objective therefor is to identify and properly treat terms that are present in both formulations in a process and observable independent manner.
In the first part the resummation scheme introduced by Yennie, Frautschi and Suura (YFS), resumming large logarithms associated with the emission of soft photons in massive Qed, is combined with fixed-order next-to-leading matrix elements. The implementation of a universal algorithm is detailed and results are studied for various precision observables in e.g. Drell-Yan production or semileptonic B meson decays. The results obtained for radiative tau and muon decays are also compared to experimental data.
In the second part the resummation scheme introduced by Dokshitzer, Gribov, Lipatov, Altarelli and Parisi (DGLAP), resumming large logarithms associated with the emission of collinear partons applicable to both Qcd and Qed, is combined with fixed-order next-to-leading matrix elements. While the focus rests on its application to Qcd corrections, this combination is discussed in detail and the implementation is presented. The resulting predictions are evaluated and compared to experimental data for a multitude of processes in four different collider environments. This formulation has been further extended to accommodate real emission corrections to beyond next-to-leading order radiation otherwise described only by the DGLAP resummation. Its results are also carefully evaluated and compared to a wide range of experimental data.
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Mooßen, Oliver [Verfasser], Michael [Gutachter] Dolg, and Michael [Gutachter] Hanrath. "Interpretation of ab initio Calculations of Cerium Compounds and Predictive Power of Density Functional Theory Calculations for Iodine Catalysis / Oliver Mooßen ; Gutachter: Michael Dolg, Michael Hanrath." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1162273518/34.
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Márquez, Costa Juan Pablo. "Caractérisation et modélisation des interfaces dans les composites organiques stratifiés à haute température : Application à la tenue au feu des structures aéronautiques PhyFire LOT 2 - Développement de modèles de comportement du composite Caractérisation en température de la ténacité en mode II des interfaces des CMO en utilisant l’effet Joule Caractérisation du comportement visqueux des interfaces CMO et influence sur la propagation de délaminage Convention PhyFIRE 2 - LOT 2 : Développement d’un cadre de modélisation pour les matériaux composites Durabilité des matériaux composites en conditions extrêmes : vers la prédiction des propriétés de tenue au feu Durability of Composite Materials under Severe Temperature Conditions : Influence of Moisture Content and Prediction of Thermo- Mechanical Properties During a Fire Towards the Prediction of Sandwich Composites Durability in Severe Condition of Temperature : A New Numerical Model Describing the Influence of Material Water Content during a Fire Scenario." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0004.
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Dans le cadre de la tenue au feu des matériaux composites, il est nécessaire d’évaluer la dégradation de leurs propriétés thermiques et mécaniques due à des pertes de masse, de la fissuration matricielle et/ou des délaminages. Néanmoins, peu d’études dans la littérature sur la tenue en température des composites aéronautiques concernent le comportement mécanique et la rupture des interfaces avant toute dégradation thermique, sujet qui est l’objet principal de ce travail. Ainsi, l’objectif est de proposer un modèle de prévision de rupture concernant tant l’amorçage que la propagation du délaminage pour des chargements thermomécaniques. Ce travail a porté en grande partie sur la caractérisation des propriétés d’interfaces à l’aide d’une analyse d’essais de propagation de fissure en mode II pour des éprouvettes chauffées par effet Joule. Ces analyses numériques montrent que le comportement du pli n’explique pas la réponse macroscopique pseudo-ductile observée expérimentalement. Ainsi, une méthode de dialogue essai-calcul, comparant les champs cinématiques mesurés par corrélation d’images numériques et ceux simulés par éléments finis, souligne l’importance du comportement visqueux à l’échelle de l’interface.C’est par une approche similaire de type FEMU que les paramètres d’une loi de rupture de type cohésif ont été identifiés en température et en tenant compte des différentes sources d’incertitude. Ce travail met en évidence la similitude entre le cisaillement plan et hors plan, tant sur le comportement que sur la rupture. En parallèle, l’analyse d’essais de tenue en température par impact laser a permis d’établir un critère d’amorçage par une approche couplée en contrainte et en énergie. Une confrontation de ce critère aux paramètres de la loi de zone cohésive identifiés précédemment permet de discuter de l’échelle de modélisation de l’interfaceWithin the framework of the fire resistance of composite materials, it is necessary to assess the degradation of their thermal and mechanical properties due to mass losses, matrix cracking and/or delamination cracks. Nevertheless, few studies in the literature about the temperature resistance of aeronautical composites concern the mechanical behaviour and the rupture of interfaces before any thermal degradation,subject which is the main topic of this work. Thus, the objective is to propose a failure model concerning both the delamination crack initiation and growth under thermomechanical loads. Much of this work has focused on the characterisation of interface properties using an analysis of mode II crack propagation tests for Joule heated specimens. These numerical analyses show that the ply behaviour does not explain the macroscopic pseudo-ductile response observed experimentally. Thus, a test-calculation dialog method, comparing the kinematic fields measured by digital images correlation and those simulated by finite elements, underlines the importance of the viscous behaviour at the interface scale. By a similar FEMU approach the parameters of a cohesive-type fracture law have been identified in temperature and taking into account the different sources of uncertainty. This work highlights the similarity between plane and out-of-plane shearing, both on behaviour and on failure. In parallel, the analysis of temperature resistance tests by laser impact made it possible to establish a crack initiation criterion by a coupled stress and energy approach. A comparison of this criterion with the parameters of the cohesive zone law previously identified makes it possible to discuss about the modeling scale of the interface
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Botha, Cornelis Petrus. "Simulation of the human energy system / Cornelis Petrus Botha." Thesis, North-West University, 2002. http://hdl.handle.net/10394/9623.
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Preface -
Biotechnology is generally accepted to be the next economical wave of the future. In order to attain
the many benefits associated with this growing industry simulation modelling techniques have to be
implemented successfully. One of the simulations that ne' ed to be performed is that of the human
energy system.
Pharmaceutical companies are currently pouring vast amounts of capital into research regarding
simulation of bodily processes. Their aim is to develop cures, treatments, medication, etc. for major
diseases. These diseases include epidemics like diabetes, cancer, cardiovascular diseases, obesity,
stress, hypertension, etc. One of the most important driving forces behind these diseases is poor
blood sugar control.
The blood glucose system is one of the major subsystems of the complete human energy system. In
this study a simulation model and procedure for simulating blood glucose response due to various
external influences on the human body is presented.
The study is presented in two parts. The first is the development of a novel concept for quantifying
glucose energy flow into, within and out of the human energy system. The new quantification unit
is called ets (equivalent teaspoons sugar). The second part of the study is the implementation of the
ets concept in order to develop the simulation model.
Development of the ets concept -
In the first part of the study the ets concept, used for predicting glycaemic response, is developed
and presented.
The two current methods for predicting glycaemic response due to ingestion of food are discussed,
namely carbohydrate counting and the glycaemic index. Furthermore, it is shown that it is currently
incorrectly assumed that 100% of the chemical energy contained in food is available to the human
energy system after consumption. The ets concept is derived to provide a better measure of
available energy from food.
In order to verify the ets concept, two links with ets are investigated. These are the links with
insulin response prediction as well as with endurance energy expenditure. It is shown that with both
these links linear relationships provide a good approximation of empirical data. It is also shown that
individualised characterisation of different people is only dependent on a single measurable variable
for each link.
Lastly, two novel applications of the ets concept are considered. The first is a new method to use the
ets values associated with food and energy expenditure in order to calculate both short-acting and
long-acting insulin dosages for Type 1 diabetics. The second application entails a new
quantification method for describing the effects of stress and illness in terms of ets.
Development of the blood glucose simulation model -
The second part of the study presents a literature study regarding human physiology, the
development for the blood glucose simulation model as well as a verification study of the
simulation model.
Firstly, a brief overview is given for the need and motivation behind simulation is given. A
discussion on the implementation of the techniques for construction of the model is also shown. The
procedure for solving the model is then outlined.
During the literature study regarding human physiology two detailed schematic layouts are
presented and discussed. The first layout involves the complex flow pathways of energy through the
human energy system. The second layout presents a detailed discussion on the control system
involved with the glucose energy pathway.
Following the literature review the model for predicting glycaemic response is proposed. The
design of the component models used for the simulations of the internal processes are developed in
detail as well as the control strategies implemented for the control system of the simulation model.
Lastly, the simulation model is applied for glycaemic response prediction of actual test subjects and
the quality of the predictions are evaluated. The verification of the model and the procedure is
performed by comparing simulated results to measured data. Two evaluations were considered,
namely long-term and short-term trials. The quality of both are determined according to certain
evaluation criteria and it is found that the model is more than 70% accurate for long-term
simulations and more than 80% accurate for short-term simulations.
Conclusion -
In conclusion, it is shown that simplified simulation of the human energy system is not only
possible but also relatively accurate. However, in order to accomplish the simulations a simple
quantification method is required and this is provided by the ets concept developed in the first part
of this study. Some recommendations are also made for future research regarding both the ets
concept and the simulation model.
Finally, as an initial endeavour the simulation model and the ets concept proposed in this study may
provide the necessary edge for groundbreaking biotechnological discoveries.PhD (Mechanical Engineering) North-West University, Potchefstroom Campus, 2003
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Jost, Michael [Verfasser], Martin [Akademischer Betreuer] Mönnigmann, and Gabriele [Akademischer Betreuer] Pannocchia. "Accelerating the calculation of model predictive control laws for constrained linear systems / Michael Jost. Gutachter: Martin Mönnigmann ; Gabriele Pannocchia." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/108242580X/34.
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Evangelista, Nathan Sombra. "Development of a method for predictive calculations density of ionic liquids in a wide range of temperature and pressure." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13986.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorIonic liquids are compounds of considerable interest due to their unique physicochemical properties. A detailed knowledge of these properties is of great importance. In particular, the liquid density is a very important property required in many design problems and, therefore, in process simulation . Experimental measurements of this property is not viable for all the existing ionic liquids . Therefore, development of new methods for its estimation is essential. In this work , a new group contribution model capable of estimating ionic liquids density over a wide range of temperatur e (251.62 â 473. 15 K) is proposed. This method ( â GCVOL - IL â ) is an extension of a reliable existing method ( âGCVOL - OL - 60â ) able to estimate the same property for organic molecular compounds at several temperatures and atmospheric pressure . Estimation of density at higher pressures (up to 300 MPa) was performed by the use of a Tait - type equation. A large databank containing 21845 experimental density data for 863 pure ionic liquids and 994 experimental data for 15 different binary mixtures of these com pounds has been applied in the development of this work . The results presented indicated that the model was able to estimate the volumetric behavior (T, P, ρ ) of various ionic liquids ( including policationic species) and of binary mixtures containing these compounds (x, T, ρ ) . The method has been compared to the best existing group contribution models able to estimate the same property. The analysis of different criteria encourage s the application and implementation of the proposed method in process simulators.
LÃquidos iÃnicos sÃo compostos possuidores de uma sÃrie de caracterÃsticas fÃsico-quÃmicas desejÃveis para diferentes aplicaÃÃes industriais. O conhecimento das suas propriedades, sobretudo da massa especÃfica, à fundamental para que eles sejam aplicados em simuladores de processos. A determinaÃÃo experimental de tal propriedade à impraticÃvel para todos os lÃquidos iÃnicos existentes, de forma que mÃtodos capazes de estima-las sÃo requeridos. Neste trabalho, à apresentado um novo mÃtodo de contribuiÃÃo de grupos capaz de estimar a massa especÃfica dessa classe de compostos em um amplo intervalo de temperatura (251,62 â 473,15 K), o qual foi denominado âGCVOL-ILâ. O mÃtodo proposto à uma extensÃo do modelo âGCVOL-OL-60â, o qual à capaz de estimar satisfatoriamente a massa especÃfica de compostos orgÃnicos moleculares a diferentes temperaturas e à pressÃo atmosfÃrica. A estimativa da massa especÃfica a altas pressÃes (atà 300 MPa) foi realizada por meio de uma equaÃÃo do tipo Tait. Para o desenvolvimento deste trabalho, foi criado um banco de dados, composto de 21845 dados experimentais de massa especÃfica para 863 diferentes lÃquidos iÃnicos puros alÃm de 994 dados experimentais para misturas binÃrias contendo compostos dessa classe. Os resultados obtidos indicam que o modelo proposto foi capaz de estimar satisfatoriamente o comportamento volumÃtrico (T, P, ρ) de uma grande variedade de lÃquidos iÃnicos puros (incluindo espÃcies policatiÃnicas), bem como o comportamento (x, T, ρ) das misturas binÃrias estudadas. Na etapa final do trabalho, o mÃtodo foi comparado com os trÃs melhores modelos de mesma natureza existentes na literatura. A anÃlise de uma sÃrie de critÃrios indicou que o mÃtodo à competitivo frente aos existentes, o que encoraja sua utilizaÃÃo e implementaÃÃo em simuladores de processos.
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Elisée, Eddy. "Towards in silico prediction of mutations related to antibiotic resistance." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS350.
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La résistance aux antibiotiques est une menace sérieuse pour la santé publique. En effet, si on ne change pas rapidement notre consommation excessive d'antibiotiques, la situation actuelle va se dégrader jusqu'à basculer dans une ère dite "post-antibiotique", dans laquelle plus aucun antibiotique ne sera efficace contre les infections microbiennes. Bien que ce phénomène de résistance apparaît naturellement, l'utilisation abusive d'antibiotiques accélère le processus. De plus, la présence de pathogènes multi-résistants neutralise l'effet des traitements existants et dans le cas de chirurgies courantes (césariennes, transplantations d'organe...), la situation peut rapidement s'aggraver voire devenir mortelle. C'est pourquoi des directives, émanant des autorités sanitaires, doivent être mises en place afin de contrôler l'utilisation des médicaments, et ce, à tous les niveaux de la société, des individus au secteur agricole en passant par les professionnels de santé et les industries pharmaceutiques. Le monde de la recherche scientifique, quant à elle, doit trouver des nouvelles stratégies pour enrayer la propagation de la résistance. Dans ce contexte, cette thèse a pour objectif le développement d'une méthode de prédiction, par calculs d'énergie libre, des mutations de β-lactamases favorables à l'hydrolyse des β-lactames. Ces travaux méthodologiques ont donc conduit au développement : (1) de nouveaux paramètres pour les enzymes à zinc, implémentés dans le champ de force OPLS-AA et validés par des simulations de dynamique moléculaire sur un panel de métalloenzymes représentatives, (2) d'un protocole de paramétrisation de ligands covalents pour étudier le comportement de certains β-lactames dans CMY-136, une nouvelle β-lactamase caractérisée au laboratoire, et (3) d'un protocole de calcul d'énergie libre évalué au moyen de compétitions internationales de prédiction. Ce dernier a ensuite été utilisé pour tenter d'expliquer pourquoi la carbamylation de la sérine catalytique n'a pas lieu dans certaines oxacillinases. Au travers de ces travaux, nous avons pu améliorer significativement notre approche computationnelle et désormais tout est en place pour une exploration exhaustive des mutations possibles dans les β-lactamasesAntibiotic resistance is a global concern threatening worldwide health. Indeed, if we don't change our overconsumption of antibiotics, the current situation could worsen until a "post-antibiotic" era in which existing treatment would be ineffective against microbial infections. Despite the natural occurrence of antibiotic resistance, the misuse of antibiotics is speeding up the process. Furthermore, presence of multi-resistant pathogens negates the effect of modern treatments and usual surgeries (caesarean sections, organ transplantations...) might be riskier in the future, or even lethal. That's why, common guidelines have to be edicted by health authorities in order to control antibiotic use at every level of society, from individuals to healthcare industry including health professionals and agriculture sector. As for scientific research, new strategies have to be considered in order to limit the spread of antibiotic resistance. In that context, the presented thesis aimed at developing a protocol to predict, by free energy calculations, β-lactamase mutations which could promote the hydolysis of β-lactams antibiotics. In order to achieve that, we developed several methodological approaches including: (1) new parameters for zinc enzymes implemented in OPLS-AA force field and thereafter validated using molecular dynamics simulations of representative zinc-containing metalloenzymes, (2) a protocol to parameterize covalent ligands in order to analyze the dynamical behavior of some β-lactams in CMY-136, a novel β-lactamase recently characterized in our laboratory, and (3) a pmx-based free energy protocol. The latter was also assessed through several international blinded prediction challenges, and finally used to find out why carbamylation of the catalytic serine is not observed in certain OXA enzymes. Throughout this work, we made significant improvements in our protocol, and now everything is in place for an exhaustive prediction of possible mutations in β-lactamases
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Becker, Caroline [Verfasser], and Rainer [Akademischer Betreuer] Böckmann. "Development of computational methods for the prediction of protein structure, protein binding, and mutational effects using free energy calculations / Caroline Becker. Gutachter: Rainer Böckmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1054331456/34.
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Stephens, Derek A. "Tools for Ergonomic Intervention: The Development and Analysis of a Cost Calculator." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1582268913341823.
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Schultz, Spencer Albert. "An Investigation into the Use of Density Functional Theory (DFT) Calculations for Predicting Vibrational Transitions for Perfluroinated Sulfonic Acid (PFSA) Ionomer Membranes." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87470.
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Perfluorinated sulfonic acid (PFSA) ionomer membranes demonstrate great potential for use in proton exchange membrane fuel cells (PEMFCs) due to their favorable electronic properties and excellent efficiency. However, the assignment of key vibrational transitions such as the symmetric sulfonate and ether stretches is not yet fully understood depriving researchers of a quick and simple technique for analyzing morphological changes. The symmetric sulfonate stretch could be used to track changes in the ionic clusters formed within the membrane while the ether stretch will provide insight into the largely semi-crystalline PTFE phase. Alterations in either regime will affect both ion transport and mechanical properties and produce a major shift in device performance.
This study focused on predicting the vibrational transitions for Aquivion, 3M PFSA, and Nafion using density functional theory (DFT) with the bulk being performed using the same functional and basis set combination, B3LPY/6-31+G*. For all three ionomers, the predicted vibrational transitions were affected by changes in both the conformer and solvation method with water being used as the solvent. Despite the noted changes, both vibrational transitions were determined to be within the range of 970-1100 cm-1 with the symmetric sulfonate stretch present at around 970-1010 cm-1 and the ether stretch observed at around 1050-1100 cm-1 with solvation present. While the calculated peak positions mirror those found in the experimental spectra within the literature, the traditional normal mode assignments do not match those predicted by our calculations. However, recent studies have hypothesized that these vibrational transitions are coupled, which could explain why they have been so difficult to assign.Master of Science
Perfluorinated sulfonic acid (PFSA) ionomer membranes show great promise for use in proton exchange membrane fuel cells (PEMFCs) due to their excellent efficiency. However, the current techniques used to determine changes in structural configurations require sophisticated equipment and trained personnel to operate. Simpler techniques exist wherein the vibrations of certain bonds can be measured upon exposure of the sample to measured amounts of infrared light. The problem with this technique is that researchers currently do not fully understand at what wavelengths certain portions of the polymer known as functional groups will vibrate. These vibrations are also known as vibrational transitions. This study was undertaken to predict through numerical solutions to the Schrödinger equation at what wavelengths two particular vibrational transitions would occur for three common ionomers, Aquivion, 3M PFSA, and Nafion. For all three structures, the positions of these transitions mirrored that observed within the literature although the functional groups assigned to these positions did not match with those identified by our calculations. However, recent studies have indicated that these vibrational transitions occur at the same positions, which could explain why they have been so difficult to assign.
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Losik, Len. "Results from the Prognostic Analysis Completed on the NASA EUVE Satellite to Measure Equipment Mission Life." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595790.
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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaThis paper addresses the research conducted at U.C. Berkeley Space Sciences Laboratory, Center for Extreme Ultra Violet Astrophysics between 1994 and 1995 on the NASA EUVE ion-orbit satellite. It includes the results from conducting a scientific analysis called a prognostic analysis completed on all satellite subsystem equipment. A prognostic analysis uses equipment analog telemetry to measure equipment remaining usable life. The analysis relates equipment transient behavior, often referred to as "cannot duplicates" in a variety of industries caused from accelerated aging to the equipment end-of-life with certainty. The analysis was confirmed by using proprietary, pattern recognition software by Lockheed Martin personnel Lockheed Martin personnel completed an exploration into the application of statistical pattern recognition methods to identify the behavior caused from accelerated aging that experts in probability reliability analysis claims cannot exist. Both visual and statistical methods were successful in detecting suspect accelerated aging and this behavior was related to equipment end of life with certainty. The long-term objective of this research was to confirm that satellite subsystem equipment failures could be predicted so that satellite subsystem and payload engineering personnel could be allocated for only the time that equipment failures were predicted to occur, lowering the cost of mission operations. This research concluded that satellite subsystem equipment remaining usable life could be measured and equipment failures could be predicted with certainty so that engineering support for mission operations could be greatly reduced.
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Bahl, Henning [Verfasser], Wolfgang F. L. [Akademischer Betreuer] Hollik, Andreas [Gutachter] Weiler, and Wolfgang F. L. [Gutachter] Hollik. "Precise prediction of MSSM Higgs boson masses combining fixed-order and effective field theory calculations / Henning Bahl ; Gutachter: Andreas Weiler, Wolfgang F. L. Hollik ; Betreuer: Wolfgang F. L. Hollik." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/116982563X/34.
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Schönherr, Marek [Verfasser], Dominik [Akademischer Betreuer] Stöckinger, and Frank [Akademischer Betreuer] Krauss. "Improving predictions for collider observables by consistently combining fixed order calculations with resummed results in perturbation theory / Marek Schönherr. Gutachter: Dominik Stöckinger ; Frank Krauss. Betreuer: Dominik Stöckinger." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1068442417/34.
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Bartsch, Ralf, Jens Sumpf, André Bergmann, and Marcus Bona. "Approach for Predicting the Friction Temperature between Thermoplastics in Dry-Running Sliding Friction with Periodically Recurring Contacts." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A31813.
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A variety of analytical and numerical approaches for calculating the friction temperature have been developed in the past. However, none is capable to estimate the friction temperature of thermoplastic friction pairings. Therefore, a semi-analytical model for predicting the friction temperature has been developed. Dry friction and periodically recurring contact is a premise. In the article the derivation is shown und influencing parameters are explained. A validation is made by experimental studies on a conveyor system. The model can be applied to sliding chain conveyor as well as perspectively similar tribological systems.
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Yao, Yongxin. "Thermodynamic prediction of glass formation tendency, cluster-in-jellium model for metallic glasses, ab initio tight-binding calculations, and new density functional theory development for systems with strong electron correlation." [Ames, Iowa : Iowa State University], 2009.
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Eriksson, Matias. "Sustainability measures in quicklime and cement clinker production." Doctoral thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-112842.
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This thesis investigates sustainability measures for quicklime and cement clinker production. It is the aim of this thesis to contribute to the effort of creating a more sustainable modus of industrial production. The methods used comprises process simulations through multicomponent chemical equilibrium calculations, fuel characterization and raw materials characterization through dynamic rate thermogravimetry. The investigated measures relate to alternative fuels, co-combustion, oxygen enrichment, oxyfuel combustion, mineral carbonation and optimizing raw material mixes based on thermal decomposition characteristics. The predictive multicomponent chemical equilibrium simulation tool developed has been used to investigate new process designs and combustion concepts. The results show that fuel selection and oxygen enrichment influence energy efficiency, and that oxyfuel combustion and mineral carbonation could allow for considerable emission reductions at low energy penalty, as compared to conventional post-combustion carbon dioxide capture technologies. Dynamic rate thermogravimetry, applied to kiln feed limestone, allows for improved feed analysis with a deeper understanding of how mixing of different feed materials will affect the production processes. The predictive simulation tool has proven to be of practical value when planning and executing production and full scale campaigns, reducing costs related to trial and error. The main conclusion of this work is that several measures are available to increase the sustainability of the industry.
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Losik, Len. "Stopping Launch Vehicle Failures Using Telemetry to Measure Equipment Usable Life." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595729.
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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaLaunch vehicle equipment reliability is driven by infant mortality failures, which can be eliminated using a prognostic analysis prior, during and/or after the exhaustive and comprehensive dynamic environmental factory acceptance testing. Measuring and confirming equipment performance is completed to increase equipment reliability by identifying equipment that fails during test for repair/replacement. To move to the 100% reliability domain, equipment dynamic environmental factory testing should be followed by a prognostic analysis to measure equipment usable life and identify the equipment that will fail prematurely. During equipment testing, only equipment performance is measured and equipment performance is unrelated to equipment reliability making testing alone inadequate to produce equipment with 100% reliability. A prognostic analysis converts performance measurements into an invasive usable life measurement by sharing test data used to measure equipment performance. Performance data is converted to usable life data provides a time-to-failure (TTF) in minutes/hours/days/months for equipment that will fail within the first year of use, allowing the production of equipment with 100% reliability.
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Flores, Livas José. "Computational and experimental studies of sp3-materials at high pressure." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10127.
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Nous présentons des études expérimentales et théoriques de disiliciures alcalino-terreux, le disilane (Si2H6) et du carbone à haute pression. Nous étudions les disiliciures et en particulier le cas d’une phase plane de BaSI2 qui a une structure hexagonale avec des liaisons sp3 entre les atomes de silicium. Cet environnement électronique conduit à un gaufrage de feuilles du silicium. Nous démontrons alors une amélioration de la température de transition supraconductrice de 6 à 8.9 K lorsque les couches de silicium s’aplanissent dans cette structure. Des calculs ab initio basés sur DFT ont guidé la recherche expérimentale et permettent d’expliquer comment les propriétés électroniques et des phonons sont fortement affectés par les fluctuations du flambage des plans de silicium. Nous avons aussi étudié les phases cristallines de disilane à très haute pression et une nouvelle phase métallique est proposé en utilisant les méthodes de prédiction de structure cristalline. Les températures de transition calculées donnant un supraconducteur autour de 20 K à 100 GPa. Ces valeurs sont significativement plus faibles comparées à celles avancées dans la littérature. Finalement, nous présentons des études de structures de carbone à haute pression à travers une recherche de structure systématique. Nous avons trouvé une nouvelle forme allotropique du carbone avec une symétrie Cmmm que nous appelons Z-carbone. Cette phase est prévue pour être plus stable que le graphite pour des pressions supérieures à 10 GPa. Des expériences et simulation de rayon-X et spectre Raman sugèrent l’existence de Z-carbone dans des micro-domaines de graphite sous pressionWe present experimental and theoretical studies of sp3 materials, alkaline-earth-metal (AEM) disilicides, disilane (Si2H6) and carbon at high pressure. First, we study the AEM disilicides and in particular the case of a layered phase of BaSi2 which has an hexagonal structure with sp3 bonding of the silicon atoms. This electronic environment leads to a natural corrugated Si-sheets. Extensive ab initio calculations based on DFT guided the experimental research and permit explain how electronic and phonon properties are strongly affected by changes in the buckling of the silicon plans. We demonstrate experimentally and theoretically an enhancement of superconducting transition temperatures from 6 to 8.9 K when silicon planes flatten out in this structure. Second, we investigated the crystal phases of disilane at the megabar range of pressure. A novel metallic phase of disilane is proposed by using crystal structure prediction methods. The calculated transition temperatures yielding a superconducting Tc of around 20 K at 100 GPa and decreasing to 13 K at 220 GPa. These values are significantly smaller than previously predicted Tc’s and put serious drawbacks in the possibility of high-Tc superconductivity based on silicon-hydrogen systems. Third, we studied the sp3-carbon structures at high pressure through a systematic structure search. We found a new allotrope of carbon with Cmmm symmetry which we refer to as Z-carbon. This phase is predicted to be more stable than graphite for pressures above 10 GPa and is formed by sp3-bonds. Experimental and simulated XRD, Raman spectra suggest the existence of Z-carbon in micro-domains of graphite under pressure
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Losik, Len. "Using Telemetry to Measure Equipment Mission Life on the NASA Orion Spacecraft for Increasing Astronaut Safety." International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581640.
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ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, CaliforniaThe surprise failure of two NASA Space Shuttles and the premature failures of satellite subsystem equipment on NASA satellites are motivating NASA to adopt an engineering discipline specifically developed for preventing surprise equipment failures. The NASA Orion spacecraft is an Apollo module-like capsule planned to replace the NASA Space Shuttle reusable launch vehicle for getting astronauts to space and return to the earth safely as well as a crew escape vehicle stored at the ISS. To do so, NASA is adopting a non-Markov reliability paradigm for measuring equipment life based on the prognostic and health management program on the Air Force F-35 Joint Strike Fighter. The decision is based on the results from the prognostic analysis completed on the Space Shuttle Challenger and Columbia that identified the information that was present but was ignored for a variety of reasons prior to both accidents. The goal of a PHM is to produce equipment that will not fail prematurely and includes using predictive algorithms to measure equipment usable life. Equipment with transient behavior, missed by engineering analysis is caused from accelerated of parts will fail prematurely with 100% certainty. With the processing speed of today's processors, transient behavior is caused from at least one part suffering from accelerated aging. Transient behavior is illustrated in equipment telemetry in a prognostic analysis but not in an engineering analysis. Telemetry is equipment performance information and equipment performance has been used to increase reliability, but performance is unrelated to equipment remaining usable life and so equipment should be failing prematurely. A PHM requires equipment telemetry for analysis and so analog telemetry will be available from all Orion avionics equipment. Replacing equipment with a measured remaining usable life of less than one year will stop the premature and surprise equipment failures from occurring during future manned and unmanned space missions.
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Losik, Len. "Using Telemetry to Measure Equipment Mission Life on the NASA Orion Spacecraft for Increasing Astronaut Safety." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595658.
Full textAbstract:
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaThe surprise failure of two NASA Space Shuttles and the premature failures of satellite subsystem equipment on NASA satellites are motivating NASA to adopt an engineering discipline that uses telemetry specifically developed for preventing surprise equipment failures. The NASA Orion spacecraft is an Apollo module-like capsule planned to replace the NASA Space Shuttle reusable launch vehicle for getting astronauts to space and return to the earth safely as well as a crew escape vehicle stored at the ISS. To do so, NASA is adopting a non-Markov reliability paradigm for measuring equipment life based on the prognostic and health management program on the Air Force F-35 Joint Strike Fighter. The decision is based on the results from the prognostic analysis completed on the Space Shuttle Challenger and Columbia that identified the information that was present but was ignored for a variety of reasons. The goal of a PHM is to produce equipment that will not fail prematurely. It includes using predictive algorithms to measure equipment usable life. Equipment with transient behavior caused from accelerated of parts will fail prematurely with 100% certainty. For many decades, it was believed that test equipment and software used to in testing and noise from communications equipment were the cause of most transient behavior. With the processing speed of today's processors, transient behavior is caused from at least one part suffering from accelerated aging. Transient behavior is illustrated in equipment telemetry in a prognostic analysis. Telemetry is equipment performance information and equipment performance has been used to increase reliability, but performance is unrelated to equipment remaining usable life and so equipment should be failing prematurely. A PHM requires equipment telemetry for analysis and so analog telemetry will be available from all Orion avionics equipment. Replacing equipment with a measured remaining usable life of less than one year will stop the premature and surprise equipment failures from occurring during future manned and unmanned space missions.
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Losik, Len. "Using Telemetry to Measure Equipment Reliability and Upgrading the Satellite and Launch Vehicle Factory ATP." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595730.
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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaSatellite and launch vehicles continues to suffer from catastrophic infant mortality failures. NASA now requires satellite suppliers to provide on-orbit satellite delivery and a free satellite and launch vehicle in the event of a catastrophic infant mortality failure. A high infant mortality failure rate demonstrates that the factory acceptance test program alone is inadequate for producing 100% reliability space vehicle equipment. This inadequacy is caused from personnel only measuring equipment performance during ATP and performance is unrelated to reliability. Prognostic technology uses pro-active diagnostics, active reasoning and proprietary algorithms that illustrate deterministic data for prognosticians to identify piece-parts, components and assemblies that will fail within the first year of use allowing this equipment to be repaired or replaced while still on the ground. Prognostic technology prevents equipment failures and so is pro-active. Adding prognostic technology will identify all unreliable equipment prior to shipment to the launch pad producing 100% reliable equipment and will eliminate launch failures, launch pad delays, on-orbit infant mortalities, surprise in-orbit failures. Moving to the 100% reliable equipment extends on-orbit equipment usable life.
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Kotrba, Martin. "Virtuální dvojče a prediktivní údržba." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417571.
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This diploma thesis deals with the design of a virtual twin of cross table MCV 754 QUICK from the Czech manufacturer Kovosvit MAS. The research part describes the basic principles of predictive maintenance methodology and virtual twin technology. The practical part includes a simplification of the initial cross table model. This model was then transferred to the simulation software MSC Adams, where it was optimized so that its behavior corresponds as closely as possible to the physical device. Several simulations were subsequently performed on the model. Then a concept for a predictive method for calculating the remaining service life of individual sections of the ball screw was presented. Simulations performed on a virtual twin served as a source of data to test the proposed method.
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Harb, Zeinab. "Détermination théorique des paramètres RMN de métabolites et protéines." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00740957.
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Ce travail présente une étude théorique des spectres RMN de molécules biologiques. Dans la première partie, les calculs DFT des paramètres RMN (déplacements chimiques et constantes de couplage spin-spin) pour les protons liés à des atomes de carbone ont été réalisés pour quatre métabolites de la prostate: la putrescine, la spermidine, la spermine, et la sarcosine, et trois métabolites du cerveau: l'acétate, l'alanine et la sérine. Une étude théorique systématique, dans l'approche DFT, des paramètres de RMN des métabolites a montré que la méthode B3LYP/6-311++G** est un bon compromis entre la précision et les coûts. Les contributions du solvant ont été évaluées en utilisant le modèle PCM, les effets des isomères, pondérés dans l'approximation de Boltzmann, ont été pris en compte, et les corrections de vibration de point zéro ont été estimées en utilisant une approche perturbative au second ordre. La comparaison avec l'expérience a démontré que tous ces effets sont nécessaires pour améliorer l'accord entre les données calculées et expérimentales, aboutissant à des résultats de grande précision. Dans la deuxième partie, nous avons développé un nouveau modèle, BioShift, qui permet la prédiction des déplacements chimiques des différents noyaux (H, N, C ...) pour des molécules biologiques (protéines, ADN, ARN, polyamine ...). Il est simple, rapide, et comporte un nombre limité de paramètres. La comparaison avec des modèles sophistiqués conçus spécialement pour la prédiction des déplacements chimiques des protéines a montré que Bioshift est concurrentiel avec de tels modèles.
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Legrand, Karim. "Correction and Optimization of 4D aircraft trajectories by sharing wind and temperature information." Thesis, Toulouse, INSA, 2019. http://www.theses.fr/2019ISAT0011/document.
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Cette thèse s'inscrit dans l'amélioration de la gestion du trafic aérien. Le vent et la température sont deux paramètres omniprésents, subis, et à l'origine de nombreux biais de prédiction qui altèrent le suivi des trajectoires. Nous proposons une méthode pour limiter ces biais. Le concept "Wind and Température Networking" améliore la prédiction de trajectoire en utilisant le vent et la température mesurés par les avions voisins. Nous détaillons les effets de la température sur l'avion, permettant sa prise en compte. L'évaluation du concept est faite sur 8000 vols. Nous traitons du calcul de trajectoires optimales en présence de vent prédit, pour remplacer les actuelles routes de l'Atlantique Nord, et aboutir à des groupes de trajectoires optimisées et robustes. Dans la conclusion, nous présentons d'autres champs d'applications du partage de vents, et abordons les besoins en nouvelles infrastructures et protocoles de communication, nécessaires à la prise en compte de ce nouveau conceptThis thesis is related to air traffic management systems current changes. On the ground and in flight, trajectory calculation methods and available data differ. Wind and temperature are two ubiquitous parameters that are subject to and cause prediction bias. We propose a concept to limit this bias. Our "Wind and Temperature Networking" concept improves trajectory prediction, using wind and temperature information from neighboring aircraft. We detail the effects of temperature on the aircraft performances, allowing for temperature to be taken into account. The concept evaluation is done on 8000 flights. We discuss the calculation of optimal trajectories in the presence of predicted winds, to replace the current North Atlantic Tracks, and to provide optimized and robust groups of trajectories. The conclusion of this thesis presents other fields of wind sharing applications, and addresses the need for new telecommunications infrastructures and protocols
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Tran, Minh Ngoc, and 陳明玉. "Prediction of Yarn Interlacing Frequency Based on Turbulent Compressible Flow Calculation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50702973627509196907.
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碩士國立臺灣科技大學
機械工程系
98
Turbulent flow fields inside several interlacing nozzles with a gas inlet of 1.3 mm diameter are simulated by compressible flow calculations. The airflow patterns inside the nozzle provide a useful insight for understanding the interlacing mechanism of yarn. In this thesis, a model based on three-dimensional flow simulation is proposed to predict the yarn interlacing frequency of nozzles, which is also validated by corresponding experimental measurements. An effective interlacing region is defined to calculate the yarn interlacing index, which correlates the flow characteristic with the yarn interlacing frequency. Seven investigated nozzles are divided into two series: the series of AB and AC. In the series of AB, nozzles A1 and B1 show better performance in the yarn interlacing than A0 and B0. The nozzle C1 is the best nozzle among the nozzles in the series of AC. The proposed model shows favorable agreement with the measured results.