Dissertationen zum Thema „Methods of Transfer“

Le transfert d‘apprentissage regroupe les méthodes permettant de transférer l’apprentissage réalisé sur des données (appelées Source) à des données nouvelles, différentes, mais liées aux données Source. Ces travaux sont une contribution au transfert d’apprentissage homogène (les domaines de représentation des Source et Cible sont identiques) et transductif (la tâche à effectuer sur les données Cible est identique à celle sur les données Source), lorsque nous ne disposons pas d’étiquettes des données Cible. Dans ces travaux, nous relâchons la contrainte d’égalité des lois des étiquettes conditionnellement aux observations, souvent considérée dans la littérature. Notre approche permet de traiter des cas de plus en plus généraux. Elle repose sur la recherche de transformations permettant de rendre similaires les données Source et Cible. Dans un premier temps, nous recherchons cette transformation par Maximum de Vraisemblance. Ensuite, nous adaptons les Machines à Vecteur de Support en intégrant une contrainte additionnelle sur la similitude des données Source et Cible. Cette similitude est mesurée par la Maximum Mean Discrepancy. Enfin, nous proposons l’utilisation de l’Analyse en Composantes Principales à noyau pour rechercher un sous espace, obtenu à partir d’une transformation non linéaire des données Source et Cible, dans lequel les lois des observations sont les plus semblables possibles. Les résultats expérimentaux montrent l’efficacité de nos approches
Transfer Learning aims to take advantage of source data to help the learning task of related but different target data. This thesis contributes to homogeneous transductive transfer learning where no labeled target data is available. In this thesis, we relax the constraint on conditional probability of labels required by covariate shift to be more and more general, based on which the alignment of marginal probabilities of source and target observations renders source and target similar. Thus, firstly, a maximum likelihood based approach is proposed. Secondly, SVM is adapted to transfer learning with an extra MMD-like constraint where Maximum Mean Discrepancy (MMD) measures this similarity. Thirdly, KPCA is used to align data in a RKHS on minimizing MMD. We further develop the KPCA based approach so that a linear transformation in the input space is enough for a good and robust alignment in the RKHS. Experimentally, our proposed approaches are very promising

L'objectiu principal d'aquesta tesi es l'estudi de la transferència d'energia per radiació. Per aquest motiu, s'ha estudiat la fenomenologia bàsica de la transferencia de calor per radiació. Tenint en compte el tipus d'equació que descriu aquesta transferència d'energia, aquesta tesi esta encarada als metodes numèrics que ens permetran incorporar la radiació en els nostres càlculs. Donat que aquest és el primer treball d'aquestes característiques en el grup de recerca CTTC ("Centre Tecnològic de Transferència de Calor"), està limitat a geometries senzilles, cartesianes i cilíndriques.

En el capítol 1 s'exposa una breu introducció a la transferència d'energia per radiació, i una explicació de les equacions que la governen. Es tracta de l'equació del transport radiatiu, formulada en termes dels coeficients d'absorció i de dispersió, i l'equació de l'energia. També s'indica quan cal tenir en compte aquest fenòmen, i a més a més, es defineixen totes les magnituds i conceptes que s'han utilitzat en aquesta tesi. També es dóna una breu descripció d'algunes simplificacions que es poden fer a les equacions governants.

El mètode de les radiositats s'explica en el capítol 2. També s'hi descriu un procediment numèric que permet calcular els factors de vista en geometries amb simetria cilíndrica, i es presenten resultats obtinguts amb el mètode descrit. Tot i que aquest capítol està una mica deslligat de la resta de la tesi, l'algoritme ideat per tractar geometries tridimensionals amb un temps computacional molt proper al de geometries bidimensionals, sense un increment de memòria apreciable, dóna uns resultats prou bons com per formar part de la tesi.

El mètode de les ordenades discretes (DOM) es detalla en el capítol 3. L'aspecte més important d'aquest mètode es l'elecció del conjunt d'ordenades per integrar l'equació del transport radiatiu. S'enumeren quines propietats han d'acomplir aquests conjunts. S'hi explica amb detall la discretització de la equació del transport radiatiu, tant en coordenades cartesianes com en cilíndriques. Es presenten també alguns resultats ilustratius obtinguts amb aquest mètode.

En el moment en que es vol resoldre un problema real, cal tenir present que el coeficients d'absorció pot dependre bruscament de la longitud d'ona de la radiació. En aquesta tesi s'ha considerat aquesta dependència amb especial interés, en el capítol 4. Aquest interès ha motivat una recerca bibliogràfica sobre la modelització aquesta forta dependència espectral del coeficient d'absorció. Aquesta recerca s'ha dirigit també a l'estudi dels diferents models numèrics existents capaços d'abordar-la, i de resoldre la equació del transport radiatiu en aquestes condicions. Es descriuen diversos mètodes, i, d'aquests, se n'han implementat dos: el mètode de la suma ponderada de gasos grisos (WSGG), i el mètode de la suma de gasos grisos ponderada per línies espectrals (SLW). S'hi presenten també resultats ilustratius.

S'han realitzat multitud de proves en el codi numèric resultant de l'elaboració d'aquesta tesi. Tenint en compte els resultats obtinguts, es pot dir que els objectius proposats a l'inici de la tesi s'han acomplert. Com a demostració de la utilitat del codi resultant, aquest ha estat integrat en un codi de proposit general (DPC), resultat del treball de molts investigadors en els darrers anys.

Aquesta esmentada integració permet la resolució de problemes combinats de transferència de calor, analitzats en els capítols 5 i 6, on la radiació s'acobla amb la transferència de calor per convecció. La influència de la radiació en la transferència total de calor s'estudia en el capítol 5, publicat a la International Journal of Heat and Mass Transfer, volum 47 (núm. 2), pàg. 257-269, 2004. En el capítol 6, s'analitza l'efecte d'alguns paràmetres del mètode SLW en un problema combinat de transferència de calor. Aquest capítol s'ha enviat a la revista Journal of Quantitative Spectroscopy and Radiative Transfer, per què en consideri la publicació.
The main objective of the present thesis is to study the energy transfer by means of radiation. Therefore, the basic phenomenology of radiative heat transfer has been studied. However, considering the nature of the equation that describes such energy transfer, this work is focussed on the numerical methods which will allow us to take radiation into account, for both transparent and participating media. Being this the first effort within the CTTC ("Centre Tecnològic de Transferència de Calor") research group on this subject, it is limited to simple cartesian and cylindrical geometries.

For this purpose, chapter 1 contains an introduction to radiative energy transfer and the basic equations that govern radiative transfer are discussed. These are the radiative transfer equation, formulated in terms of the absorption and scattering coefficients, and the energy equation. It is also given a discussion on when this mode of energy transfer should be considered. In this chapter are also defined all of the magnitudes and concepts used throughout this work. It ends with a brief description of some approximate methods to take radiation into account.

The Radiosity Irradiosity Method is introduced in chapter 2. In this chapter it is also described a numerical method to calculate the view factors for axial symmetric geometries. The main results obtained in such geometries are also presented. Although a little disconnected from the rest of the present thesis, the algorithm used to handle "de facto"' three dimensional geometries with computation time just a little longer than two dimensional cases, with no additional memory consumption, is considered worthy enough to be included in this work.

In chapter 3, the Discrete Ordinates Method (DOM) is detailed. The fundamental aspect of this method is the choice of an ordinate set to integrate the radiative transfer equation. The characterization of such valuable ordinate sets is laid out properly. The discretization of the radiative transfer equation is explained in etail. The direct solution procedure is also outlined. Finally, illustrative results obtained with the DOM under several conditions are presented.

In the moment we wish to solve real problems, we face the fact that the absorption and scattering coefficients depend strongly on radiation wavelength. In the present thesis, special emphasis has been placed on studying the radiative properties of real gases in chapter 4. This interest resulted on a bibliographical research on how the wavenumber dependence of the absorption coefficient is modeled and estimated. Furthermore, this bibliographical research was focussed also on numerical models able to handle such wavenumber dependence. Several methods are discussed, and two of them, namely the Weighted Sum of Gray Gases (WSGG) and the Spectral Line Weighted sum of gray gases (SLW), have been implemented to perform non gray calculations. Some significant results are shown.

Plenty of tests have been performed to the numerical code that resulted from the elaboration of this thesis. According to the results obtained, the objectives proposed in this thesis have been satisfied. As a demonstration of the usefulness of the implemented code, it has been succesfully integrated to a general purpose computational fluid dynamics code (DPC), fruit of the effort of many researchers during many years.
Results of the above integration lead to the resolution of combined heat transfer problems, that are analyzed in chapters 5 and 6, where radiative heat transfer is coupled to convection heat transfer. The effect of radiation on the total heat transfer is studied in chapter 5, which has been published as International Journal of Heat and Mass Transfer, volume 47 (issue 2), pages 257--269, year 2004. In chapter 6, the impact of some parameters of the SLW model on a combined heat transfer problem is analyzed. This chapter has been submitted for publication at the Journal of Quantitative Spectroscopy and Radiative Transfer.

Chemistry
Ph.D.
High Pressure Liquid Chromatography (HPLC) is a well-known and widely used analytical technique which is prevalent throughout the pharmaceutical industry as a research tool. Despite its prominence HPLC possesses some disadvantages, most notably slow analysis time and large consumption of organic solvents. Ultra Pressure Liquid Chromatography (UPLC) is a relatively new technique which offers the same separation capabilities of HPLC with the added benefits of reduced run time and lower solvent consumption. One of the key developments which facilitate the new UPLC technology is sub 2-µm particles used as column packing material. These particles allow for higher operating pressures and increased flow rates while still providing strong separation. Although UPLC technology has been available since early 2000, few laboratories have embraced the new technology as an alternative to HPLC. Besides the resistance to investing in new capital, another major roadblock is converting existing HPLC methodology to UPLC without disruption. This research provides a framework for converting existing HPLC methods to UPLC. An existing HPLC method for analysis of Galantamine hydrobromide was converted to UPLC and validated according to ICH guidelines. A series of statistical evaluations on the validation data were performed to prove the equivalency between the original HPLC and the new UPLC method. This research presents this novel statistical strategy which can be applied to any two methodologies to determine parity.
Temple University--Theses

Ultra-High field (7T) MRI provides high sensitivity which allows for new qualitative and quantitative methodologies to be developed, that provide clinically useful information. The work presented in this thesis is focussed on developing a quick and reliable quantitative MT and CEST methodology, taking account of the difficulties encountered at high field. The method developed here has been tested on various studies, in both healthy and diseased brain, in an effort to aid the understanding of myelination in the human brain. The work in this thesis uses the quantitative measure of MT as a marker for myelination, and it shows strong correlations between MT-based myelination and functional connectivity, as well as very strong correlation between MT and NOE. These findings showcase the potential of NOE as a myelin marker as well, as long as the MT vs. NOE relationship remains the same in pathology. Myelination is investigated (via MT and NOE) in Multiple Sclerosis (MS) and Glioma, showing a strong coupling between the two exists even in pathology. Amide Proton Transfer (APT) is also investigated in Glioma, showing similar trends to MT and NOE. High resolution anatomical images can provide valuable information on the extend of the pathology, but quantitative information of the NMR properties of tissue (like MT, NOE and APT) has the potential to detect earlier abnormalities, and give a quantitative measure of healing or degeneration caused by pathology.

Light scattering in turbid media is essential for such diverse applications as paperand print, computer rendering, optical tomography, astrophysics and remote sensing.This thesis investigates angular variations of light reflected from plane-parallelturbid media using both mathematical models and reflectance measurements, dealswith several applications and proposes novel computational methods for solving thegoverning equations.Angular variations of light reflected from plane-parallel turbid media is studiedusing both mathematical models and reflectance measurements. It is found that thelight is reflected anisotropically from all media encountered in practice, and that theangular variations depend on the medium absorption and transmittance and on theangular distribution of the incident light. If near-surface bulk scattering dominates,as in strongly absorbing or highly transmitting media or obliquely illuminated media,relatively more light is reflected in large polar (grazing) angles. These results areconfirmed by measurements using a set of paper samples. The only situation withisotropic reflectance is when a non-transmitting, non-absorbing medium is illuminateddiffusely, and it is shown that this is the only situation where the widely usedKubelka-Munk model is exactly valid.A number of applied problems is studied, including reflectance measurements,angle resolved color and point spreading. It is seen that differences in instrumentdetection and illumination geometry can result in measurement differences. The differencesare small and if other sources of error — such as fluorescence and gloss— are not eliminated, the differences related to instrument geometry become difficultto discern. Furthermore, the dependence of point spreading in turbid mediaon the medium parameters is studied. The asymmetry factor is varied while maintainingconstant the optical response in a standardized measurement geometry. It isseen that the point spreading increases as forward scattering becomes more dominant,and that the effect is larger if the medium is low-absorbing with large meanfree path. It is argued that the directional inhomogeneity of the scattering mediummust be captured by the model to reproduce experimental results. Finally, the angleresolved color of a set of paper samples is assessed both theoretically and experimentally.The chroma decreases and the lightness increases as the observation polarangle increases. The observed differences are clearly large, and a modification ofthe L∗a∗b∗ formalism including angle dependent chromatic adaptation is suggestedhere to handle this situation. The long standing issue of parameter dependence in the Kubelka-Munk modelis partially explained by recognizing that light reflected from paper samples in standardizedmeasurements has angular variations, and by using the appropriatemodelin the calculation of the scattering and absorption coefficients.The radiative transfer (RT) equation is solved with a recently proposed particlemethod (DFPM), both in standard cases and in cases previously considered intractable.Fluorescence is added to the RT equation, thus including wavelength asan additional dimension, and this equation is solved using DFPM. The discrete RTequation can be written as a system of linear equations, and a comprehensive analysisof the convergence properties of DFPM when solving this type of problems ispresented.

The purpose of this master’s thesis is to explain and analyze whether today’s existing regulations provide sufficient guidance on how to apply the Profit Split Method (PSM) in practice. Since the enterprises’ profits arising from intra-group transactions increases, the tax base for any government also becomes larger and more important. This issue will likely become even more problematic as the globalization branches out and the majority of the global trade is undertaken between associated enterprises.

In order to satisfy all parts and serve the dual objective of securing an appropriate tax base in each jurisdiction and avoiding double taxation, one ambition of the OECD is to harmonize the transfer pricing rules and make them become more uniform. An area in which this goal can be accomplish is at an international level such as the OECD; an important developer in the field of transfer pricing. Different transfer pricing methods has been developed which can be applied by both taxpayers and tax authorities to determine a correct transfer price. Six of these methods has gained international acceptance, although to a more or less extent among various countries, and one of these methods is the PSM. In the years between 1979 and 1995, the OECD had a reluctant standpoint of accepting the application of any transfer pricing method based on profits, such as the PSM. This hesitant viewpoint changed in the existing TPG which explicitly stipulates that the PSM could provide a transfer pricing estimation in accordance with the ALP, which should be accepted in exceptional cases.

There are certain situations where a PSM possibly will provide the most appropriate arm’s length result. Since the principle of economics can create complex business environments of both vertical and horizontal integration, contributions of valuable intangibles on both sides of the cross-border transaction, the PSM might be the only method which can be employed. A relevant issue which need to be enlightened is whether the existing guidance provided by the OECD and USA is sufficient from a practitioners and tax administration point of view, or is more guidance needed to better understand the issues surrounding the concept of the PSM. The fact that OECD insist of using comparables to the highest extent as possible when employing the PSM entails practical problems, since it is rather a rule than an exception that reliable comparables cannot be found when valuable intangibles are involved.

The Arthur of this master’s thesis has identified three key conclusions which might facilitate how PSM issues can be handled in the future and improve the existing PSM guidance. These conclusions are the need for a uniform PSM interpretation, the need for additional flexibility and acceptance, and the need for additional TPG guidance.

The main problem in this thesis is: How should research and development results regarding production methods be represented for better adoption by SMEs? Manufacturing SMEs in Sweden have in general low profit margins and risk to go bankrupt. Different production methods could facilitate the needed performance improvement. Networking provides an arena where research and development needs could be determined and effective transfer activities could be carried through. How new production methods could be characterized and represented are presented. Several case studies, surveys and literature studies have been carried through. The results from these studies have been analyzed and compared to literature on the production method diffusion process – Dissemination-Clustering-Transfer. This analysis has resulted in a specification of requirements on how new production methods should be presented for better adoption by SMEs. One suggestion to the specification of requirements, the DFMTsme process, is described. The process is based on a repeated development procedure and follows a six-step development process in five phases. It is concluded that the DFMTsme process works. The research project is finally reviewed due to verification, validation and the contribution to knowledge. Implications for actors in the production method diffusion process as well as for policy makers are discussed.
QC 20100729

Modern computational science permits the accurate solution of nonlinear partial differential equations (PDEs) on overlapping computational domains, known as an overset approach. The complex grid interconnectivity inherent in the overset method can introduce errors in the solution through “orphan” points, i.e., grid points for which reliable solution donor points cannot be located. For this reason, a variety of data transfer strategies based on scattered data interpolation techniques have been assessed with application to both overset and hybrid methodologies. Scattered data approaches are attractive because they are decoupled from solver type and topology, and may be readily applied within existing methodologies. In addition to standard radial basis function (RBF) interpolation, a novel steered radial basis function (SRBF) interpolation technique has been developed to introduce data adaptivity into the data transfer algorithm. All techniques were assessed by interpolating both continuous and discontinuous analytical test functions. For discontinuous functions, SRBF interpolation was able to maintain solution gradients with the steering technique being the scattered-data analog of a slope limiter. In comparison with linear mappings, the higher-order approaches were able to more accurately preserve flow physics for arbitrary grid configurations. Overset validation test cases included an inviscid convecting vortex, a shock tube, and a turbulent ship airwake. These were studied within unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations to determine quantitative and qualitative improvements when applying RBF interpolation over current methods. The convecting vortex was also analyzed on a grid configuration which contained orphan points under the state-of-the-art overset paradigm. This was successfully solved by the RBF-based algorithm, which effectively eliminated orphans by enabling high-order extrapolation. Order-of-magnitude reductions in error compared to the exact vortex solution were observed. In addition, transient conservation errors that persisted in the original overset methodology were eliminated by the RBF approach. To assess the effect of advanced mapping techniques on the fidelity of a moving grid simulation, RBF interpolation was applied to a hybrid simulation of an isolated wind turbine rotor. The resulting blade pressure distributions were comparable to a rotor simulation with refined near-body grids.

Thesis (Ph. D. in Biomedical Engineering)--Harvard-MIT Program in Health Sciences and Technology, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 108-126).
Chemical exchange saturation transfer (CEST) is a relatively new magnetic resonance imaging (MRI) acquisition technique that generates contrast dependent on tissue microenvironment, such as protein concentration and intracellular pH. CEST imaging has the potential to become an important biomarker in a wide range of disorders. As an indicator of tissue pH, CEST imaging may allow the identification of the ischemic penumbra in stroke, and predict chemo- and radiation therapy outcomes in cancer. As a marker of protein concentration, CEST may be able to delineate tumor margins without contrast enhancement, identify disease onset in Alzheimer's disease, and monitor cartilage repair therapies. Despite several promising pilot studies, CEST imaging has had limited clinical application due to two main technical challenges. First, CEST imaging is extremely sensitive to magnetic field inhomogeneity. Images suffer from large susceptibility artifacts unless specialized BO inhomogeneity correction methods are employed that tremendously increase scan time. Second, the CEST contrast cannot be separated from the intrinsic macromolecular magnetization transfer (MT) asymmetry and brain images reflect the MT properties of white and gray matter rather than the desired protein and pH contrast. We have developed a novel CEST imaging acquisition scheme, dubbed saturation with frequency alternating RF irradiation (SAFARI), designed to be insensitive to Bo inhomogeneity and MT asymmetry. Studies in healthy volunteers demonstrate that SAFARI is robust in the presence of BO inhomogeneity and eliminates the need for specialized BO correction, thereby reducing scan time. In addition, results show that SAFARI removes the confounding MT asymmetry. We applied SAFARI imaging towards the study of the saturation transfer contrast in patients with high grade glioma. Results show that the contrast in brain tumors, which was previously attributed to an increase in the CEST signal from amide protons due to an elevated protein concentration, is instead the result of the loss of MT asymmetry found in the normal brain. Therefore, our work has lead to a new understanding of the different sources of signal in saturation transfer images of the brain with important implications for the design and analysis of future CEST studies of brain tumors.
by Rachel Nora Scheidegger.
Ph.D.in Biomedical Engineering

As Internet of Things (IoT) technology continues to become more commonplace, demand for self-sustainable and low-power networking schemes has increased. Future IoT devices will require a ubiquitous energy source and will need to be capable of low power communication. RF energy can be harvested through ambient or dedicated RF sources to satisfy this energy demand. In addition, these RF signals can be modified to convey information. This thesis surveys a variety of RF energy harvesting methods. A new low complexity energy harvesting system (circuit and antenna) is proposed. Low power communication schemes are examined, and low complexity and efficient transmitter designs are developed that utilize RF backscattering, harmonics, and intermodulation products. These communication schemes operate with minimal power consumption and can be powered solely from harvested RF energy. The RF energy harvester and RF-powered transmitters designs are validated through simulation, prototyping, and measurements. The results are compared to the performance of state-of-the-art devices described in the literature.
Master of Science
Future devices are expected to feature high levels of interconnectivity and have long lifetimes. RF energy from dedicated power beacons or ambient sources, such as Wi-Fi, cellular, DTV, or radio stations can be used to power these devices allowing them to be battery-less. These devices that harvest the RF energy can use that energy to transmit information. This thesis develops various methods to harvest RF energy and use this energy to transmit information as efficiently as possible. The designs are verified through simulation and experimental results.

Published Article
The reasons, objects, means and methods for a transfer of scientific results to society are analysed in the article. Among this, knowledge transfer - especially technology transfer - and on projects, especially joint projects with the aim of creating or transferring knowledge are concentrated upon. Success factors for bringing science to support socioeconomic development also receive attention.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 193-199).
In this thesis, we develop methods for solving the linearized Boltzmann transport equation (BTE) in the relaxation-time approximation for describing small-scale solidstate heat transfer. We first discuss a Monte Carlo (MC) solution method that builds upon the deviational energy-based Monte Carlo method presented in [J.-P. Péraud and N.G. Hadjiconstantinou, Physical Review B, 84(20), p. 205331, 2011]. By linearizing the deviational Boltzmann equation we formulate a kinetic-type algorithm in which each computational particle is treated independently; this feature is shown to be consequence of the energy-based formulation and the linearity of the governing equation and results in an "event-driven" algorithm that requires no time discretization. In addition to a much simpler and more accurate algorithm (no time discretization error), this formulation leads to considerable speedup and memory savings, as well as the ability to efficiently treat materials with wide ranges of phonon relaxation times, such as silicon. A second, complementary, simulation method developed in this thesis is based on the adjoint formulation of the linearized BTE, also derived here. The adjoint formulation describes the dynamics of phonons travelling backward in time, that is, being emitted from the "detectors" and detected by the "sources" of the original problem. By switching the detector with the source in cases where the former is small, that is when high accuracy is needed in small regions of phase-space, the adjoint formulation provides significant computational savings and in some cases makes previously intractable problems possible. We also develop an asymptotic theory for solving the BTE at small Knudsen numbers, namely at scales where Monte Carlo methods or other existing computational methods become inefficient. The asymptotic approach, which is based on a Hilbert expansion of the distribution function, shows that the macroscopic equation governing heat transport for non-zero but small Knudsen numbers is the heat equation, albeit supplemented with jump-type boundary conditions. Specifically, we show that the traditional no-jump boundary condition is only applicable in the macroscopic limit where the Knudsen number approaches zero. Kinetic effects, always present at the boundaries, become increasingly important as the Knudsen number increases, and manifest themselves in the form of temperature jumps that enter as boundary conditions to the heat equation, as well as local corrections in the form of kinetic boundary layers that need to be superposed to the heat equation solution. We present techniques for efficiently calculating the associated jump coefficients and boundary layers for different material models when analytical results are not available. All results are validated using deviational Monte Carlo methods primarily developed in this thesis. We finally demonstrate that the asymptotic solution method developed here can be used for calculating the Kapitza conductance (and temperature jump) associated with the interface between materials.
by Jean-Philippe Péraud.
Ph. D.

Chemical exchange saturation transfer (CEST) imaging is a novel contrast mechanism in magnetic resonance imaging. CEST allows for the indirect detection of chemical groups that contain exchangeable protons. The contrast from endogenous CEST agents in the human brain is sensitive to changes in pH and protein structures. Therefore, CEST imaging offers a potential tool for the non-invasive detection of pathologies such as stroke and cancer. However, clinical implementation of current CEST MRI sequences is hindered by a lack of contrast-to-noise ratio (CNR) per unit time. Furthermore, confounding effects which contribute to the development of CEST contrast make interpretation of this contrast difficult. This thesis examines the underlying physical effects that govern the development of CEST contrast and aims to improve clinical CEST sequences. The ability to correctly identify CEST parameters from z-spectra was investigated through simulations of the Bloch-McConnell equations. Conventional least squares fitting methods are inherently sensitive to changes in the bulk water. Reducing the sampling of the bulk water frequencies improved the sensitivity of this method to the exchange rate. In vitro experiments using conventional non-interleaved CEST sequences demonstrated that reduction of the longitudinal magnetisation close to the bulk water frequencies is dominated by T₁ relaxation. Minimisation of the inversions of the bulk water reduced the longitudinal component of the direct water saturation (DWS) effect. Implementation of additional acquisition events allowed for the transverse component of DWS to be used for imaging. Interleaved CEST sequences were used in phantoms to study the effect of the interleaved readout excitations. Optimal flip angles, α, for the readout pulses fulfilled the OBJ condition 0 < α < α^ernst and allowed compromise between optimal CEST contrast and signal-to-noise ratio (SNR). Reducing SNR in favour of CNR made the interleaved CEST sequences more prone to coherence pathway artefacts. Hexagonal spoiling in interleaved CEST reduced this problem. Finally, in vivo experiments showed that confounding effects such as T₁ can be used as a contrast mechanism to optimise CEST sequences directly in healthy volunteers where conventional stroke contrasts are lacking.

Aeration of wastewater is performed in many wastewater treatment plants to supply oxygen to microorganisms. To evaluate the performance of a single aerator or an aeration system, there is a standard method for oxygen transfer measurements in clean water used today. The method includes a model that describes the aeration process and the model parameters could be estimated using nonlinear regression. The model is a simplified description of the oxygen transfer which could possibly result in performance results that are not accurate. That is why many have tried to describe the aeration at other ways and with other parameters. The focus of this Master Thesis has been to develop alternative models which better describe the aeration that could result in more accurate performance results. Data for model evaluations have been measured in two different tanks with various numbers of aerators. Five alternative methods containing new models for oxygen transfer evaluation have been studied in this thesis. The model in method nr 1 assumes that the oxygen transfer is different depending on where in a tank the dissolved oxygen concentration is measured. It is assumed to be faster in a water volume containing air bubbles. The size of the water volumes and the mixing between them can be described as model parameters and also estimated. The model was evaluated with measured data from the two different aeration systems where the water mixing was relatively big which resulted in that the model assumed that the whole water volume contained air bubbles. After evaluating the results, the model was considered to maybe be useful for aeration systems where the mixing of the water volumes was relatively small in comparison to the total water volume. However, the method should be further studied to evaluate its usability. Method nr 2 contained a model with two separate model parameter, one for the oxygen transfer for the air bubbles and one for the oxygen transfer at the water surface. The model appeared to be sensitive for which initial guesses that was used for the estimated parameters and it was assumed to reduce the model’s usability. Model nr 3 considered that the dissolved oxygen equilibrium concentration in water is depth dependent and was assumed to increase with increasing water depth. Also this model assumed that the oxygen was transferred from both the air bubbles and at the water surface. The model was considered to be useful but further investigations about whether the saturation concentrations should be constant or vary with water depth should be performed. The other two methods contained models that were combinations of the previous mentioned model approaches but was considered to not be useful.

 

This master’s thesis discusses and analyzes difficulties in transfer pricing methods’ applicability to intangibles. With basis from the OECD Transfer Pricing Guidelines and the U.S. regulations, this thesis investigates applicable methods in legislation, theory, recommendations, case law and how they are applied in practice.

The OECD Guidelines do not provide an exact solution to the valuation of a transfer of intangibles between controlled parties. It refers to the arm’s length principle to determine whether the price set for a transfer between controlled parties is the same, as unrelated parties would have paid, under the same circumstances.

The best method rule used in the U.S. has no preferred order of application although it provides specific methods to be applied to intangibles. In the U.S., as in most countries (and recommended by the OECD), the Comparable Uncontrolled Price/Comparable Uncontrolled Transaction methods are considered most reliable if comparables can be identified.

The profit split method is recommended if there are no comparable transactions available and is applicable to non-routine intangibles. Other methods that require comparables are however used in the application of the profit split method to set an arm’s length price on routine functions. This method will probably become more popular in the future since it is not as dependent on comparables as most other transfer pricing methods.

There are several other methods and approaches to the arm’s length principle, which shows the complexity of intangibles and the ambition to find some form of standard.

This master’s thesis has identified the problems with most of the methods applied to intangibles relying on comparables to some extent. The comparability factors concerning intangibles are a problem, as they are difficult to apply strictly and a frequent problem is the limited access to information. A majority of available agreements published in databases are strongly focused on U.S. based enterprises transactions and rarely disclose all the required details. As a result, the comparables used become less reliable since the geographical area, size of the enterprise and functions compared seldom are comparable with the tested party or transaction. In some industry sectors, it is almost impossible to find independent comparables, especially for non-routine intangibles.

The discrepancy between theory and practice is shown through the usage and acceptance by tax authorities and courts, of comparables without sufficient comparability. This simplified and practical approach to transfer pricing derives from the limited availability of information and the need to avoid unreasonable requirements on the MNEs to produce transfer pricing benchmarking in particular and documentation in general.

 

 

Denna magisteruppsats diskuterar och analyserar svårigheterna med internprissättningsmetoders tillämplighet på immateriella tillgångar. Med utgångspunkt från OECD:s riktlinjer och de amerikanska reglerna, undersöker denna uppsats lagstiftningen, teorin, rekommendationer och rättsfall rörande tillämpliga metoder och hur de tillämpas i praktiken.

OECD:s rekommendationer ger ingen direkt lösning på värderingen av transaktionen av immateriella tillgångar mellan parter i intressegemenskap. Den hänvisar till armlängdsprincipen för att avgöra huruvida priset på en transaktion mellan kontrollerade parter är samma som okontrollerade parter skulle ha betalat under samma omständigheter.

Best method rule som används i USA ger inget krav på i vilken ordning metoderna ska användas även om den omfattar särskilda metoder som skall tillämpas på immateriella tillgångar. I USA, liksom i de flesta länder (och rekommenderat av OECD), anses Comparable Uncontrolled Price/Comparable Uncontrolled Transaction metoderna vara de mest tillförlitliga om jämförbara transaktioner kan identifieras.

Profit split metoden rekommenderas om det inte finns några jämförbara transaktioner tillgängliga och kan användas på icke rutinmässiga immateriella tillgångar. Andra metoder som kräver jämförbara transaktioner används dock vid tillämpningen av profit split metoden för att bestämma ett armslängdsmässigt pris på rutinmässiga funktioner. Denna metod kommer troligen att bli mer populärt i framtiden eftersom den inte är lika beroende av jämförbara transaktioner som de flesta andra internprissättningsmetoder.

Det finns flera andra metoder och strategier för att bestämma ett armlängsmässigt pris vilket visar immateriella tillgångars komplexitet och ambitionen att hitta någon form av standard.

Denna magisteruppsats har påvisat problematiken med att de flesta metoder som tillämpas på immateriella tillgångar använder i viss utsträckning jämförbara transaktioner. Kompabilitetskraven på de jämförbara immateriella tillgångarna utgör ett problem eftersom de är svåra att tillämpa strikt och ett återkommande problem är den begränsade tillgången till information. En majoritet av de tillgängliga avtalen publiceras i databaser som är starkt fokuserad på amerikanska företags transaktioner och sällan ges alla nödvändiga uppgifter. Detta resulterar i sämre tillförlitlighet på de jämförbara transaktionerna, eftersom det geografiska området, storleken på företagen och dess funktioner sällan är jämförbara med de testade parterna eller transaktionerna. I vissa branscher är det näst intill omöjligt att hitta oberoende jämförbara transaktioner, särskilt för icke-rutinmässiga immateriella tillgångar.

Skillnaden mellan teori och praktik visas genom användandet, skattemyndigheters och domstolars accepterande, av transaktioner utan tillräcklig jämförbarhet. Detta förenklade och praktiska tillvägagångssätt beror på den begränsade tillgången på information och behovet av att undvika orimliga krav på multinationella företag att producera jämförbarhetsanalyser och dokumentation till internprissättningen

 

In this thesis, exact and semiclassical approaches are derived for predicting wave energy distributions in coupled cavities with variable material properties. These approaches are attractive because they can be extended to more complex built-up systems. For the exact treatment, we describe a multi-component boundary element method. We point out that depending on the boundary conditions and the number of interfaces between sub-components, it may be advantageous to use a normal derivative method to set up the integral kernels. We describe how the arising hypersingular integral kernels can be reduced to weakly singular integral and then using the piecewise constant collocation method. The normal derivative method can be used to minimise the number of weakly-singular integrals thus leading to BEM formulations which are easier to handle. The second component of this work concerns a novel approach for finding an exact formulation of the transfer operator. This approach is demonstrated successfully for a disc with boundary conditions changing discontinuously across the boundary. Such an operator captures the diffraction effects related to the change of boundary conditions. So it incorporates boundary effects such as diffraction and surface waves. A comparison between the exact results from the BEM against the exact transfer operator shows good agreement between both categories. Such an exact operator converges to the semiclassical Bogomolny transfer operator in the semiclassical limit. Having seen how the exact transfer operator behaves for a unit disc, a similar approach is adapted for the coupled cavity configuration resulting in the semiclassical transfer operator. Our formulation for the transfer operator is applicable not only for the quantization of a system, but also to recover the Green function.

Engine components are commonly exposed to air temperatures exceeding the thermal material limit in order to increase the overall engine performance and to maximise the engine specific fuel consumption. To prevent the overheating of the materials and thus the reduction of the component life, an internal flow system must be designed to cool the critical engine parts and to protect them. As the coolant flow is bled from the compressor and not used for the combustion an important goal is to minimise the amount of coolant in order to optimise the overall engine performance. Predicting the metal temperatures is of paramount importance as they are a major factor in determining the component stresses and lives. In addition, as modern engines operate in ever harsher conditions due to efficiency requirements, the ability to predict thermo-mechanical displacements becomes very relevant: on the one hand, to prevent damage of components due to excessive rubbing, on the other hand, to understand how much air is flowing internally within the secondary air system for cooling and sealing purposes, not only in the design condition but throughout the engine life-span. In order to achieve this aero-engine manufacturers aim to use more and more accurate numerical techniques requiring multi-physics models, including thermo-mechanical finite elements and CFD models, which can be coupled in order to investigate small variations in temperatures and displacements. This thesis shows a practical application and extension of a numerical methodology for predicting conjugate heat transfer. Extensive use is made of FEA (solids) and CFD (fluid) modeling techniques to understand the thermo-mechanical behaviour of a turbine stator well cavity, due to the interaction of cooling air supply with the main annulus. Previous work based on the same rig showed diffculties in matching predictions to thermocouple measurements near the rim seal gap. In this investigation, further use is made of existing measurements of hot running seal clearances in the rig. The structural deflections are applied to the existing model to evaluate the impact in flow interactions and heat transfer. Furthermore, for one test case unsteady CFD simulations are conducted in order to take into account the flow unsteadiness in the heat transfer predictions near the rim. In addition to a baseline test case without net ingestion, a case simulating engine deterioration with net ingestion is validated against the available test data, also taking into account cold and hot running seal clearances. Furthermore an additional geometry with a stationary deflector plate is modelled and validated for the same flow cases. Experiments as well as numerical simulations have shown that due to the deflector plate the cooling flow is fed more directly into the disc boundary layer, allowing more effective use of less cooling air, leading to improved engine efficiency. Therefore, the deflector plate geometry is embedded in a CFD-based automated optimisation loop to further reduce the amount of cooling air. The optimisation strategy concentrates on a flexible design parameterisation of the cavity geometry with deflector plate and its implementation in an automatic 3D meshing system with respect of finally executing an automated design optimisation. Special consideration is given to the flexibility of the parameterisation method in order to reduce design variables to a minimum while also increasing the design space flexibility & generality. The parameterised geometry is optimised using a metamodel-assisted approach based on regressing Kriging in order to identify the optimum position and orientation of the deflector plate inside the cavity. The outcome of the optimisation is validated using the benchmarked FEA-CFD coupling methodology.

Prior to the last reform of the transfer pricing regime, only the application of specific valuation methods was allowed, which generated several practical and constitutional problematic issues. These were partially solved with the recent inclusion of a provision that allows the application of “other methods”. This paper analyzes the issues of the previous situation, as well as the solutions presented by the reform and its corresponding limits. Finally, the authors propose several precisions that, in their opinion, should be included in the regulation of the “other methods”.
Previamente a la última reforma del régimen peruano de precios de transferencia, solo se permitía la aplicación de métodos específicos de valoración, lo que generó una serie de problemas de índole práctica y constitucional. Estos se resolvieron parcialmente con la reciente inclusión de una disposición que permite la aplicación de “otros métodos”. El presente trabajo analiza la problemática de la situación previa, así como las soluciones que presenta la reforma y sus límites. Por último, se propone una serie de precisiones que, a juicio de los autores, deberían incluirse en la reglamentación de los “otros métodos”.

Radiative transfer theory describes the interaction of radiation with scattering and absorbing media. It has applications in neutron transport, atmospheric physics, heat transfer, molecular imaging, and others. In steady state, the radiative transfer equation is an integro-differential equation of five independent variables. This high dimensionality and presence of integral term present a serious challenge when trying to solve the equation numerically. Over the past 50 years, several techniques for solving the radiative transfer equation have been introduced. These include, but are certainly not limited to, Monte Carlo methods, discrete-ordinate methods, spherical harmonics methods, spectral methods, finite difference methods, and finite element methods. Methods involving discrete ordinates have received particular attention in the literature due to their relatively high accuracy, flexibility, and relatively low computational cost. In this thesis we present a discrete-ordinate discontinuous Galerkin method for solving the radiative transfer equation. In addition, we present a generalized Fokker-Planck equation that may be used to approximate the radiative transfer equation in certain circumstances. We provide well posedness results for this approximation, and introduce a discrete-ordinate discontinuous Galerkin method to approximate a solution. Theoretical error estimates are derived, and numerical examples demonstrating the efficacy of the methods are given.

Sebastian Zetterström, Master of Science in energy systems, Mälardalens University in Västerås. Abstract of Master’s thesis, submitted 16th of August. Evaluation of a suction pyrometer by heat and mass transfer methods. The aim of the thesis is to evaluate the cooling of a specific suction pyrometer which is designed by Jan Skvaril, doctorate at Mälardalens University. First part is explained how the balances and correlations are performed before being implemented in MATLAB, after this  a ANSYS Fluent model is constructed and explained, which is used for the comparison of results. The cooling is performed by using water at an inlet temperature of 10°C and an assumed flue gas temperature of 810°C. Sensitivity analysis are performed to test the stability of the models which yield good results for stability, done by adjusting both flue gas temperature and inlet cooling water temperature which are as well presented for observation. From doing further MATLAB sensitivity analysis which show that the model still performs well and is stable. The resulting cooling water is heated to approximately 24, 8°C and the flue gas is cooled to 22, 4°C, in ANSYS Fluent the answer differs approximately 2°C and results in 20, 4°C which can be considered by looking at the flue gas inlet temperature of 810°C that this can be deemed an insignificant change and can therefore conclude that the comparison between the two platforms match each other good and that calculations can be considered accurate. Keywords:  Suction pyrometer, cooling, heat transfer, thermal resistance network, MATLAB, ANSYS Fluent, simulation

High-commitment call-centers kännetecknas av investeringar i HR-praktiker såsom utbildning, vilka kräver transfer till arbetet för att generera avkastning på investeringen. Studien ämnade undersöka hur demografiska profiler relaterar till transfereffekter, self-efficacy och prestation. Den ämnade även undersöka vikten av antal utbildningstillfällen för self-efficacy och prestation samt faktorer som hindrar/faciliterar transfer. En multi-methods sequential explanatory design användes, där två studier genom-fördes på ett svenskt call-center som utförde en utbildningsinsats. I studie 1 samlades data in med en enkät (n = 51) och i studie 2 genomfördes intervjuer (n = 6). I studie 1 identifierades tre kluster med skilda demo-grafiska bakgrunder, bl.a. ålder och utbildningsnivå. En signifikant skillnad i transfer återfanns dem emellan. Neutral transfer återfanns och self-efficacy var högst hos deltagare som slutfört utbildningen. I studie 2 framkom att det upplevdes viktigt att utbildningens nytta var tydlig och att ett neutralt transferklimat rådde. Studierna antyder att hänsyn bör tas till det övergripande transfersystemet tillsammans med individen för att bäst facilitera transfer.

Thermal properties of complex suspension flows are investigated using numerical computations. The objective is to develop an efficient and accurate computational method to investigate heat transport in suspension flows. The method presented here is based on solving the lattice Boltzmann equation for the fluid phase, as it is coupled to the Newtonian dynamics equations to model the movement of particles and the energy equation to find the thermal properties. This is a direct numerical simulation that models the free movement of the solid particles suspended in the flow and its effect on the temperature distribution. Parallel implementations are done using MPI (message passing interface) method. Convective heat transfer in internal suspension flow (low solid volume fraction, φ<10%), heat transfer in hot pressing of fiber suspensions and thermal performance of particle filled thermal interface materials (high solid volume fraction, φ>40%) are investigated. The effects of flow disturbance due to movement of suspended particles, thermo-physical properties of suspensions and the particle micro structures are discussed.

Research on transfer of training highlights the importance of implementing a set of cognitive-based strategies after training, i.e., post-training transfer interventions, to help trainees achieve positive transfer. In this respect, prior research has considered two types of post-training transfer interventions: relapse prevention and proximal plus distal goal setting. However, despite the advances in recent research linking post-training transfer interventions and transfer of training, there are several key problems that remain under-explored, including the lack of agreement about which post-training transfer intervention types are more efficient to improve transfer performance, the inconclusiveness of the impact of post-training transfer interventions on transfer of training, and the lack of clarity on the process through which post-training transfer interventions affect trainee attitudes and transfer of training (i.e., the mechanism issue). This thesis is attempting to address these problems by investigating the effects of two post-training transfer interventions (i.e., relapse prevention and proximal plus distal goal setting) on trainees' readiness to change, autonomous motivation to transfer, and transfer of training. The data were collected using a sequential mixed method approach involving experimental design and semi-structured interviews. In total, there were 378 employees from two organisational sectors (i.e., public and private sector) in Indonesia participated in the study. The data were analysed using split-plot analysis of variance, partial least square analysis, and content analysis. The findings show that both relapse prevention and proximal plus distal goal setting influence trainees' readiness to change, autonomous motivation to transfer and transfer of training. This study also reveals several complex interactions involving trainees' creativity and initiative that may explain the mechanism linking post-training transfer interventions, trainee attitudes, and transfer of training. By elucidating this mechanism, this thesis helps scholars to organise the large and diverse body of mechanisms on the post-training transfer interventions and transfer of training literature.

A comprehensive knowledge about the infiltration situation in a sewer system is required for sustainable operation and cost-effective maintenance. Due to the high expenditures of infiltration measurements an optimisation of necessary measurement campaigns and a reliable transfer of measurement results to comparable areas are essential. Suitable methods were developed to improve the information yield of measurements by identifying appropriate measuring point locations and to assign measurement results to other potential measuring points by comparing sub-catchments and classifying reaches. The methods are based on the introduced similarity approach “Similar sewer conditions lead to similar infiltration/inflow rates” and on modified multivariate statistical techniques. The developed methods have a high degree of freedom against data needs. They were successfully tested on real and generated data. For suitable catchments it is estimated, that the optimisation potential amounts up to 40 % accuracy improvement compared to non-optimised measuring point configurations. With an acceptable error the transfer of measurement results was successful for up to 75 % of the investigated sub-catchments. With the proposed methods it is possible to improve the information about the infiltration status of sewer systems and to reduce the measurement related uncertainty which results in significant cost savings for the operator.
Für den nachhaltigen Betrieb und die kosteneffiziente Unterhaltung von Kanalnetzen ist eine genaue Bestimmung ihrer Fremdwassersituation notwendig. Eine Optimierung der dazu erforderlichen Messkampagnen und eine zuverlässige Übertragung der Messergebnisse auf vergleichbare Gebiete sind aufgrund der hohen Aufwendungen für Infiltrationsmessungen angezeigt. Dafür wurden geeignete Methoden entwickelt, welche einerseits den Informationsgehalt von Messungen durch die Bestimmung optimaler Messpunkte verbessern und andererseits Messresultate mittels Vergleichen von Teileinzugsgebieten und Klassifizierungen von Kanalhaltungen zu anderen potenziellen Messstellen zuordnen. Die Methoden basieren auf dem Ähnlichkeitsansatz “Ähnliche Kanaleigenschaften führen zu ähnlichen Fremdwasserraten” und nutzen modifizierte multivariate statistische Verfahren. Sie haben einen hohen Freiheitsgrad bezüglich der Datenanforderung. Die Methoden wurden erfolgreich anhand gemessener und generierter Daten validiert. Es wird eingeschätzt, dass das Optimierungspotenzial bei geeigneten Einzugsgebieten bis zu 40 % gegenüber nicht optimierten Mess-netzen beträgt. Die Übertragung der Messergebnisse war mit einem akzeptablen Fehler für bis zu 75 % der untersuchten Teileinzugsgebiete erfolgreich. Mit den entwickelten Methoden ist es möglich, den Kenntnisstand über die Fremdwassersituation eines Kanalnetzes zu verbessern und die messungsbezogene Unsicherheit zu verringern. Dies resultiert in Kostenersparnissen für den Betreiber.

La consommation énergétique des bâtiments est directement impactée par les variables climatiques et en particulier par la température, la radiation solaire, la pression atmosphérique, l’humidité relative et la vitesse du vent. La maîtrise de la performance hygrothermique des bâtiments permet la conception d’ouvrage à faible consommation énergétique intégrant des enveloppes durables et dépourvues de risques de pathologies liées à l’humidité. Ainsi, les architectes et constructeurs nécessitent de disposer d’outils, pour simuler les performances de l’enveloppe sur le long terme, qui reposent sur des modèles précis, fiables et rapides.Plusieurs modèles ont été proposés dans la littérature pour investiguer les transferts de chaleur et de masse dans les matériaux poreux composant les bâtiments. Généralement, les équations régissant les phénomènes sont résolues en employant des méthodes conventionnelles basées sur les différences finies ou les volumes finis combinés avec des schémas temporels implicites. Cependant, ces méthodes imposent des sous-itérations, coûteuses en temps de calculs, pour traiter les non linéarités du problème. De plus, elles exigent des discrétisations très fines qui augmentent significativement les temps de calcul des simulations. Par conséquent, ces travaux de recherches se concentrent sur le développement et l’analyse de méthodes numériques pour simuler de manière efficiente les problèmes de transferts de chaleur et de masse dans les matériaux poreux.Dans la première partie de cette thèse, des schémas améliorés par rapport aux approches traditionnelles sont proposés pour éliminer les sous-itérations coûteuses pour traiter les non linéarités, pour améliorer l’ordre de précision et pour diminuer les temps de calculs. Nonobstant les progrès réalisés avec les nouveaux schémas numériques, les conclusions de cette première partie montrent que nous manipulons toujours des systèmes d’équations de grandes dimensions, en particulier lorsqu’il s’agit de problèmes de transferts multidimensionnels. Pour cette raison, afin de diminuer d’avantage les coûts de calcul et la taille du modèle, un modèle d’ordre réduit basé sur les méthodes spectrales est proposé subséquemment. Il garantit une prédiction précise des phénomènes physiques. De plus, le degré de liberté de la solution est fortement réduit tout en préservant la fidélité du modèle. Le coût de calcul est nettement inférieur à celui du modèle complet originel.L’ensemble de ces méthodes sont appliquées à des problèmes relatifs aux phénomènes physiques intervenant dans les bâtiments, tels que les transferts mono ou multi-couches, la recherche de l’épaisseur optimale d’isolation, les mécanismes de tampons hygroscopiques ou encore les transferts à l’échelle de bâtiments mono- ou bi-zones. En conclusion, nous démontrons comment construire des modèles numériques efficaces, en termes de temps de calculs et précision, pour l’investigation des transferts de chaleur et de masse dans les matériaux poreux
Building energy consumption is directly impacted by weather parameters such as temperature, solar radiation, atmospheric pressure, relative humidity and wind velocity. The knowledge of the building hygrothermal performance enables the design of energy efficient buildings and the prediction of overall durability and sustainability of envelopes. Therefore, designers and builders are interested in modeling the long-term performance of the envelopes by means of accurate, reliable and fast simulation tools.Several numerical models have been proposed in the literature to study the heat and moisture transfer in building materials. In general, this problem is solved by traditional methods, such as finite-difference and finite-volume methods, using mainly implicit schemes. Nevertheless, these methods impose costly sub-iterations to treat the nonlinearities and very fine discretization, which increase substantially the simulation computational cost. Therefore, this research has been focused on the development and analyses of numerical methods for efficiently simulate the problem of heat and mass transfer through porous materials.In the first part of this thesis, improved schemes of the traditional numerical methods have been developed to eliminate costly sub-iterations to treat nonlinearities, to improve the order of accuracy and to save computer run time. Despite the great progress with the new numerical schemes, the conclusion of the first part shows that we still have to deal with large systems of equations, particularly when treating multi-dimensional transfer problems. For this reason, to reduce even more the computational burden and the size of the system, a reduced-order model, based on spectral methods is proposed in the sequence to provide an accurate description of the physical phenomena. The degrees of freedom of the solution is strongly decreased while maintaining the model fidelity. It ensures a computational cost much lower than the complete original model.All these methods are applied to problems related to building physics, such as single and multilayer nonlinear transfer, the determination of optimum insulation thickness, the process of moisture buffer effects and transfer in one- or two-zone building models. In conclusion, we show how to build efficient numerical models, in terms of computational cost and accuracy, to investigate the heat and mass transfer in porous materials

The available body of biomedical literature is increasing at a high pace, exceeding the ability of researchers to promptly leverage this knowledge-rich amount of information. Although the outstanding progress in natural language processing (NLP) we observed in the past few years, current technological advances in the field mainly concern newswire and web texts, and do not directly translate in good performance on highly specialized domains such as biomedicine due to linguistic variations along surface, syntax and semantic levels. Given the advances in NLP and the challenges the biomedical domain exhibits, and the explosive growth of biomedical knowledge being currently published, in this thesis we contribute to the biomedical NLP field by providing efficient means for extracting semantic relational information from biomedical literature texts. To this end, we made the following contributions towards the real-world adoption of knowledge extraction methods to support biomedicine: (i) we propose a symbolic high-precision biomedical relation extraction approach to reduce the time-consuming manual curation efforts of extracted relational evidence (Chapter 3), (ii) we conduct a thorough cross-domain study to quantify the drop in performance of deep learning methods for biomedical edge detection shedding lights on the importance of linguistic varieties in biomedicine (Chapter 4), and (iii) we propose a fast and accurate end-to-end solution for biomedical event extraction, leveraging sequential transfer learning and multi-task learning, making it a viable approach for real-world large-scale scenarios (Chapter 5). We then outline the conclusions by highlighting challenges and providing future research directions in the field.

Bottlebrush polymers are interesting topologies that have become increasingly relevant in various applications including rheology modifiers, super-soft elastomers, photonic crystals, anti-fouling coatings, the in vivo delivery of therapeutic agents, and as promising substrates in lithographic printing. These macromolecules are comprised of numerous polymeric side-chains densely grafted to a polymer backbone. The densely grafted nature of bottlebrush polymers results in steric repulsion between neighboring polymer chains, forcing these macromolecules to adopt a chain-extended conformation. Although these remarkable macromolecules have a many different applications, the transformative potential of the bottlebrush polymer topology has not been realized because the synthesis of high molecular weight bottlebrush polymers is challenging. This dissertation focusses on improving the synthesis of these large macromolecules using the grafting-through strategy in the first section and the transfer-to strategy in the second section. For the first time the effect of anchor group chemistry—the configuration of atoms linking the polymer to a polymerizable norbornene—was studied on the kinetics of ring-opening metathesis polymerization (ROMP) of macromonomers (MMs) initiated by Grubbs 3rd generation catalyst. A variance in the rate of propagation of >4-fold between similar MMs with different anchor groups was observed. This phenomenon was conserved across all MMs tested, regardless of solvent, molecular weight (MW), or repeat unit identity. Experimental and computational studies indicated that the rate differences likely resulted from a combination of varying steric demands and electronic structure among the different anchor groups. This new insight will allow others to achieve high MM conversion and prepare pure, high MW bottlebrush polymers by ROMP grafting-through. The second section of this dissertation deals with a little studied bottlebrush synthesis technique called the transfer-to method. This method is a hybrid of the grafting-from and grafting-to approaches in which the growing polymer side chains detach from the backbone, propagate freely in solution, and then reattach to the backbone in a chain transfer step. Several parameters were investigated to determine optimal conditions for this process. This study provides for the first time a guide to use the transfer-to method to produce high purity bottlebrush polymers with controllable backbone and side chain length.
Ph. D.

The study reported in this thesis investigates the source language of lexical transfer in multilingual learners using a mixed methods approach. Previous research has shown that the source language of crosslinguistic influence can be related to factors such as proficiency, recency/exposure, psychotypology, the L2 status, and item-specific transferability. The present study employed a mixed methods approach in order to best serve the particularities of each of the five factors under investigation. Multinomial logistic regression was emloyed to test the predictive power of the first four factors, thereby addressing the issue of confounding variables found in previous studies. A more exploratory qualitative analysis was used to investigate item-specific transferability due to the lack of prior empirical studies focusing on this aspect. Both oral and written data were collected, offering an analysis of modal differences in direct comparison. The results show a significant effect of proficiency and exposure, but inconsistent patterns for psychotypology. Most importantly, in this study of lexical transfer, a significant L1 status effect was found, rather than an L2 status effect. In addition, the statistical model predicted the source language of transfer better in the spoken than in the written mode. Finally, learners were found to assess, as well as actively improve, an item’s transferability in relation to target language norms and constraints. All of these findings contribute to our understanding of lexical organization, activation, and access in the multilingual mind.

The demand for engineering graduates in the United States continues to grow, yet the number of students entering post-secondary education is declining, and graduation rates have seen little to no change over the last several decades. Engineering transfer students are a growing population and can help meet the nation's needs, however, there is little research on the persistence of this population after they transfer to the receiving institution. Student persistence is dependent on a complex set of interactions over time. Management systems engineering provides a framework for working with complex systems through system analysis and design, with a focus on the interactions of the system components. This research includes multiple management systems engineering analysis methods used to define and develop a systems view of engineering transfer student persistence. This work includes a comprehensive literature review to identify factors affecting engineering transfer student persistence, an empirical analysis of an institutional dataset, and development of a simulation model to demonstrate the throughput of engineering transfer student. Findings include 34 factors identified in the literature as affecting engineering student persistence. A review of the literature also highlighted two important gaps in the literature, including a focus on post-transfer success almost exclusively in the first post-transfer year and a significant interest in vertical transfer students, with little consideration given to lateral transfer students. The empirical analysis addressed the gaps found in the literature. Vertical and lateral engineering transfer students were found to experience different levels of transfer shock which also impacts their 4-year graduation rates. The analysis also found transfer shock was not unique to the first post-transfer term, it was also present in the second and third post-transfer terms, and reframed as transfer adjustment. The simulation model uncovers leaving patterns of engineering transfer students which include the students leaving engineering in the second year, as well as those graduating with an engineering degree in the third year. Overall this research identifies explicit factors that affect engineering transfer student persistence and suggests a new systems engineering approach for understanding student persistence and how institutions can affect change.
Doctor of Philosophy
The United States continues to need more students graduating with a bachelor's degree in engineering. To meet this demand, higher education institutions are investing more time to learn how to increase the number of engineering graduates. One method is through increasing the number of students that start and finish an engineering degree. There are two types of students enrolled in engineering degrees. The first type are students that begin a bachelor's degree at a 4year institution after completion of high school; these students are known as first-time, full-time (FTFT). The second type of student are transfer students who begin at one institution and move to another. The transfer students could have started at another 4-year institution, or they may begin at a 2-year community college. There has been a significant focus on increasing the number of FTFT students starting and finishing an engineering degree. However, there is little research on engineering transfer students and their ability to finish an engineering degree after transferring. The throughput of a student in the higher education system is a complex set of interaction over time that results in either the student earning a degree or not earning a degree. Systems engineering is a field of engineering that focuses of the design of complex system and is well-suited to be applied to better understanding student throughput. This purpose of this research is to introduce systems engineering methodologies to determine what affects the persistence of engineering transfer students, i.e., finishing an engineering degree. The research findings indicate more attention should be given to engineering transfer students in their second year of enrollment. Findings also suggest that engineering transfer students should not be considered as one population. There are several types of engineering transfer students and they each have different experiences during their transfer process which influence their ability to finish an engineering degree.

To understand how the brain functions, we must investigate the transient interactions that underpin communication between cortical regions. EEG possesses the optimal temporal resolution to capture functional connectivity, but it lacks the spatial resolution to identify the cortical locations responsible. To circumvent this problem electrophysiological connectivity should be investigated at the source level. There are many quantifiers of connectivity applied to EEG data, but some are not sensitive to the direct, or indirect, influence of one region over another, and others require the specification of a priori models so are unsuitable for exploratory analyses. Transfer Entropy (TE) can be used to infer the direction of linear and non-linear information exchange between signals over a range of time-delays within EEG data. This thesis explores the creation of a new method of mapping dynamic brain connectivity using a trial-based TE analysis of EEG source data, and the application of this technique to the investigation of semantic and number processing within the brain. The first paper (Chapter 2) documents the analyses of a semantic category and number magnitude judgement task using traditional ERP techniques. As predicted, the well-known semantic N400 component was found, and localised to left ATL and inferior frontal cortex. An N365 component related to number magnitude judgement was localised to right superior parietal regions including the IPS. These results offer support for the hub-and-spoke model of semantics, and the triple parietal model of number processing. The second paper (Chapter 3) documents an analysis of the same data with the new trial-based TE analysis. Word and number data were analysed at 0-200ms, 200-400ms, and 400-600ms following stimulus presentation. In the earliest window, information exchange was occurring predominately between occipital sources, but by the latest window it had become spread out across the brain. Task-dependent differences of regional information exchange revealed that temporal sources were sending more information to occipital sources following words at 0-200ms. Furthermore, the direction and timing of information movement within a front-temporal-parietal network was identified during 0-400ms of the number magnitude judgment. The final paper (Chapter 4), documents an attempt to track the influence of TMS through the brain using the TE analysis. TMS was applied to bilateral ATL and IPS because they are both important hubs in the brain networks that support semantic and number processing respectively. Left ATL TMS influenced sources located primarily in wide-spread left temporal lobe, and inferior frontal and inferior occipital cortices. The anatomical connectivity profile of the temporal lobe suggests that these are all plausible locations, and they exhibited excellent spatial similarities to the results of neuroimaging experiments that probed semantic knowledge. The analysis of right ATL TMS obtained a mirror image of the left. Left parietal stimulation resulted in a bilateral parietal, superior occipital, and superior prefrontal influence, which extended slightly further in the ipsilateral hemisphere to stimulation site. A result made possible by the short association and callosal fibres that connect these areas. Again, the results at the contralateral site were a virtual mirror image. The thesis concludes with a review of the experimental findings, and a discussion of methodological issues still to be resolved, ideas for extensions to the method, and the broader implications of the method on connectivity research.

This study was performed to increase knowledge of oxygen mass transfer (kLa) and mixing times in the scale-up of disposable bioreactors.Results of oxygen mass transfer studies showed kLa to increase with increasing agitation and aeration rates. By maintaining a scale-up constant such as gassed power to volume or shear, an almost constant kLa was achieved during scale-up from 50 to 2000 L. Using the scale-up constant Pg/V resulted in statistically higher kLa values at greater reactor volumes. Mixing times were revealed to be significantly affected by agitation, but not by the aeration rates tested. No pattern was recognized in the mixing time data over an increase in volume. Commonly used methods for predicting kLa upon scale-up were compared to experimental data. New coefficients were determined to fit the historic models to the parameters of this study, namely the unique geometry and low agitation and aeration rates used in the single-use systems. Each of the resulting four models was found to have average error rates from 16-23%. Although the error rates are not statistically different, the Moresi and Patete model was determined to be most conceptually accurate. The Moresi and Patete model found kLa to be more dependent on aeration than on the power input. This finding was consistent with the results of the experimental studies. The results of this study were for aeration rates (0.02-0.04 vvm) and agitation rates (Pg/V range of 2-20 W/m3) that are commonly used in single-use bioreactor systems.

Conjugate heat transfer is a crucial issue in a number of turbulent engineering fluidflow applications, particularly in nuclear engineering and heat exchanger equipment. Temperature fluctuations in the near-wall turbulent fluid lead to similar fluctuationsin the temperature of the solid wall, and these fluctuations in the solid cause thermalstress in the material which may lead to fatigue and finally damage. In the present study, the Reynolds Average Navier-Stokes (RANS) modelling approachhas been adopted, with four equation k−ε−θ2−εθ eddy viscosity based modelsemployed to account for the turbulence in the fluid region. Transport equations forthe mean temperature, temperature variance, θ2, and its dissipation rate, εθ, have beensimultaneously solved across the solid region, with suitable matching conditions forthe thermal fields at the fluid/solid interface. The study has started by examining the case of fully developed channel flow withheat transfer through a thick wall, for which Tiselj et al. [2001b] provide DNS dataat a range of thermal activity ratios (essentially a ratio of the fluid and solid thermalmaterial properties). Initial simulations were performed with the existing Hanjali´cet al. [1996] four-equation model, extended across the solid region as described above. However, this model was found not to produce the correct sensitivity to thermal activityratio of the near wall θ2 values in the fluid, or the decay rate of θ2 across the solid wall. Therefore, a number of model refinements are proposed in order to improve predictionsin both fluid and solid regions over a range of thermal activity ratios. These refinementsare based on elements from a three-equation non-linear EVM designed to bring aboutbetter profiles of the variables k, ε, θ2 and εθ near the wall , and their inclusion is shownto produce a good matching with the DNS data of Tiselj et al. [2001b].Thereafter, a further, more complex test case has been investigated, namely an opposedwall jet flow, in which a hot wall jet flows vertically downward into an ascendingcold flow. As in the channel flow case, the thermal field is also solved across the solidwalls. The modified model results are compared with results from the Hanjali´c modeland LES and experimental data of Addad et al. [2004] and He et al. [2002] respectively. In this test case, the modified model presents generally good agreement with the LESand experimental data in the dynamic flow field, particularly the penetration point ofthe jet flow. In the thermal field, the modified model also shows improvements in the θ2predictions, particularly in the decay of the θ2 across the wall, which is consistent withthe behaviour found in the simple channel flow case. Although the modified model hasshown significant improvements in the conjugate heat transfer predictions, in some instancesit was difficult to obtain fully-converged steady state numerical results. Thusthe particular investigation with the inlet jet location shows non-convergence numericalresults in this steady state assumption. Thus, unsteady flow calculations have beenperformed for this case. These show large scale unsteadiness in the jet penetration area. In the dynamic field, the total rms values of the modelled and mean fluctuations showgood agreement with the LES data. In the thermal field calculation, a range of the flowconditions and solid material properties have been considered, and the predicted conjugateheat transfer predicted performance is broadly in line with the behaviour shownin the channel flow.

This Ph.D. thesis focuses on: (i) the design and integration of a polarimetric channel for the multi-spectral Raman lidar station of the Universitat Politècnica de Catalunya (UPC), Remote Sensing, Antennas, Microwaves and Superconductivity Group (CommSensLab), (ii) the study of the temporal and spatial evolution of atmospheric aerosol optical, microphysical and radiative properties by means of active and passive remote sensing in the context of ACTRIS and Spanish National projects, and (iii) rainfall rate retrieval by means of a vertically-pointed ceilometer in the context of the Verification of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE). The first goal of this Ph.D., tested on the UPC multi-spectral Raman lidar station, consists of developing a secondary optical receiving chain, installed next to the laser source. The secondary telescope, mounted in the optical chain, allows retrieving the cross-polarized return signal separately from the total-power signal, avoiding the need of a very precise characterization of the crosstalk parameters of the beam-splitters. The first experimental results, corresponding to a collection of atmospheric conditions over the city of Barcelona, are also presented. The second goal of this Ph.D. deals first with the GAME (Global Atmospheric Model) code, necessary to retrieve the aerosol radiative properties. The radiative fluxes estimated in the short-wave and long-wave spectral ranges at the bottom and the top of the atmosphere by GAME are compared to the ones retrieved by a different radiative transfer model, namely Two-Stream, in order to know the importance of the spectral parameterization of a radiative transfer code. Then, GAME code, in both configurations, is fed by means of three different datasets to evaluate the parameterization of the vertically-resolved properties and to assess the uncertainty of GAME when is tuned with input parameters from different sources. Afterwards, an evaluation of the seasonal variability of the aerosol background optical and radiative properties in the Western Mediterranean Basin (WMB) is performed by means of AERONET (Aerosol Robotic Network) sun-photometers data from two background sites, Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). In addition, in order to detect possible northeast-southwest gradients in the aerosol properties, a third site located at Abolrán (Alborán Island, Spain) is considered. Finally, during 15-24 June 2013 a moderate Saharan dust multi-intrusion was detected by some EARLINET/ACTRIS (Granada, Barcelona, Naples, Potenza and Serra la Nave (Italy)) and ADRIMED/ChArMEx (Cap d’en Font, (Minorca Island, Spain) and Ersa) stations. This Ph.D. uses this event to study the spatio-temporal evolution of the mineral dust properties, since the lidar stations were supported during the multi-intrusion by collocated AERONET sun-photometers and the Falcon 20 aircraft. Also the GAME code is used to estimate the aerosol radiaite effect during the Saharan dust event. Besides, air- and space-borne lidar measurements, satellite images and back-trajectories are used to confirm the multi-intrusion aspect of the event. The last goal of this Ph.D. pursues estimation of the rain rate (RR) from ceilometer measurements. In VORTEX-SE, a Vaisala CL-31 ceilometer, a S-band radar, and a disdrometer were deployed in Alabama during March-April 2016. First, rain-extinction coefficients from ceilometer attenuated backscatter measurements are derived by means of a modified form of the well-known slope-method. These coefficients are compared with the RRs measured by a collocated S-band radar and a disdrometer in order to get the RR-to-extinction models. Advanced covariance-weighted techniques are used to best assess and validate the estimated models. These models can be used to estimate the RR from the ceilometer in similar situations without need to have a collocated cooperative instrument permanently deployed.
Este Ph.D. se centra en: (i) en el diseño e integración de un canal polarimétrico para la estación lidar multi espectral del grupo de teledetección, antenas, microondas y superconductividad (CommSensLab) de la Universitat Politècnica de Catalunya (UPC), (ii) en el estudio de la evolución temporal y espacial de las propiedades ópticas, microfísicas y radiativas de los aerosoles por medio de teledetección activa y pasiva en el contexto de ACTRIS y proyectos estatales, y (iii) en la recuperación de intensidad de lluvia por medio de un ceilómetro en configuración vertical en el contexto del proyecto Verification of the Origins of Rotation in Tornadoes Experiment Southeast (VORTEX-SE). El primer objetivo, realizado en la estación lidar de UPC, consiste en el desarrollo de una cadena óptica secundaria instalada junto al láser. El telescopio secundario, montado en la cadena óptica, permite recuperar la componente cross-polarized de la señal total por separado, evitando la necesidad de conocer con precisión los parámetros de los beam-splitters. Se presentan también los primeros resultados obtenidos en Barcelona durante diferentes situaciones atmosféricas. El segundo objetivo de este Ph.D. se centra en el código GAME (Global Atmospheric Model), necesario para recuperar las propiedades radiativas de los aerosoles. Los flujos radiativos estimados tanto en onda larga como en onda corta en la base y en la parte superior de la atmósfera son comparados con los estimados por otro código de transferencia radiativa, Two-Stream, para conocer la importancia de la parametrización espectral. Después, el código GAME es alimentado con 3 bases de datos diferentes para evaluar la parametrización de las propiedades resueltas en altura y conocer la incertidumbre de GAME cuando es alimentado con parámetros con diferentes orígenes. Por otro lado, se presenta una evaluación de la variabilidad estacional de las propiedades ópticas y radiativas del aerosol de fondo en la cuenca oeste mediterránea (WMB) realizada con datos de fotómetros solares de la red AERONET (Aerosol Robotic Network) situados en dos puntos considerados libres de contaminación: Ersa (isla de Córcega, Francia) y Palma de Mallorca. Además, para detectar posibles gradientes noreste-suroeste en las propiedades delos aerosoles, se considera un tercer punto ubicado en la isla de Alborán. Por último, en este Ph.D. se aprovecha una multi intrusión moderada de polvo sahariano, detectada entre los días 15 y 24 de junio de 2013 por algunas estaciones EARLINET/ACTRIS (Granada, Barcelona, Nápoles, Potenza y Serra la Nave (Italia)) y ADRIMED/ChArMEx (Cap d'en Font (Menorca) y Ersa), para estudiar la evolución espacio-temporal de las propiedades del polvo mineral, ya que las estaciones lidar estaban apoyadas durante el evento por fotómetros solares pertenecientes a la red AERONET, situados junto a las estaciones lidar, y por vuelos del Falcon 20. GAME es usado para obtener también el efecto radiativo de los aerosoles durante el evento de polvo sahariano. Para confirmar el aspecto de multi intrusión se utilizan medidas lidar tomadas a bordo de aviones y satélites, imágenes satelitales y retro trayectorias. El último objetivo del Ph.D. persigue la estimación de la RR utilizando medidas de un ceilómetro. En VORTEX-SE, se desplegaron (Alabama, marzo-abril 2016) un ceilómetro Vaisala CL-31, un radar de banda S y un disdrómetro. Se han estimado los coeficientes de extinción debida a la lluvia a partir del retorno atenuado medido por el ceilómetro, utilizando una versión modificada del método de la pendiente. Estos coeficientes se comparan con las intensidades de lluvia (RR) estimadas con el radar y el disdrómetro para obtener modelos de RR-extinción. Para validarlos se utilizan técnicas avanzadas de covarianza ponderada. Dichos modelos pueden usarse para estimar la RR con un ceilómetro, en situaciones similares, sin necesidad de tener desplegado permanentemente un instrumento cooperativo.

In the operation, planning and design of the transmission system it is of greatest concern to quantify the reliability security margin to unwanted conditions. The deterministic N-1 criterion has traditionally provided this security margin to reduce the consequences of severe conditions such as widespread blackouts. However, a deterministic criterion does not include the likelihood of different outage events. Moreover, experience from blackouts shows, e.g. in Sweden-Denmark September 2003, that the outages were not captured by the N-1 criterion. The question addressed in this thesis is how this system security margin can be quantified with probabilistic methods. A quantitative measure provides one valuable input to the decision-making process of selecting e.g. system expansions alternatives and maintenance actions in the planning and design phases. It is also beneficial for the operators in the control room to assess the associated security margin of existing and future network conditions.

This thesis presents a method that assesses each component's risk to an insufficient transfer capability in the transmission system. This shows on each component's importance to the system security margin. It provides a systematic analysis and ranking of outage events' risk of overloading critical transfer sections (CTS) in the system. The severity of each critical event is quantified in a risk index based on the likelihood of the event and the consequence of the section's transmission capacity. This enables a comparison of the risk of a frequent outage event with small CTS consequences, with a rare event with large consequences.

The developed approach has been applied for the generally known Roy Billinton Test System (RBTS). The result shows that the ranking of the components is highly dependent on the substation modelling and the studied system load level.

With the restriction of only evaluating the risks to the transfer capability in a few CTSs, the method provides a quantitative ranking of the potential risks to the system security margin at different load levels. Consequently, the developed reliability based approach provides information which could improve the deterministic criterion for transmission system planning.