Dissertations / Theses on the topic 'Copper Losses'

Copper losses to slag are generally between 0.7-2.3% during the copper matte smelting stage. In this study, the aim was to reduce these losses in the slag phase. For this purpose, usage of some additives (especially calcined colemanite labeled as CC, boric oxide-B2O3 and calcium oxide-CaO as well) as flux material was investigated. The flash furnace matte-slag (FFM-FFS) obtained from Eti Copper Inc. and a master matte-slag (MM-MS) produced synthetically were used as starting materials. Additives were tested in various amounts under two different atmospheres (N2 and low Po2 obtained by mixture of CO2/CO gases). Temperature and duration were also used as experimental variables. Experimental results have indicated that 2 hours was sufficient to obtain a low copper content in slag about 0.3% and 0.4% for FFS and MS, respectively. It was also seen that the copper content in slag decreased with increasing CC addition at all oxygen partial pressures and at all temperatures. Furthermore, the addition of all additives up to 4% had great influence in lowering the copper content in the final slags (~0.3%Cu). From FactSage calculations, it could be concluded that the colemanite addition decreased the liquidus temperature which led to early melting of slag and allowed enough duration for settling of matte particles within the slag without substantial changing its viscosity, which resulted in less mechanical copper losses to the slag. By using colemanite in copper production, it was possible that a new application area for boron compounds which are produced in Turkey could be created.

This thesis presents a study of the effects of inter-bar currents on inductionmotor starting performance and stray-load losses. The work is focused on theperformance differences between aluminium and copper casted rotors.A method to predict the stator current when starting direct-on-line isdeveloped. This includes modelling of skin-effect, saturation of the leakageflux paths and additional iron losses. The results are verified by measurements.An analytical model accounting for inter-bar currents is derived, andthe dependency of the harmonic rotor currents on the inter-bar resistivity isinvestigated. It is found that the inter-bar currents can have considerableeffect on motor starting performance and stray-load losses, the amount beingstrongly dependent on the harmonic content of the primary MMF.Based on measurements of inter-bar resistivity, the starting performanceof an aluminium and a copper casted rotor is simulated. The results indicatea higher pull-out torque of the aluminium rotor than for the equivalent copperrotor. This is rather due to an increase of the fundamental starting torque ofthe aluminium rotor, than due to braking torques from the space harmonicsin the copper rotor. The results are verified by measurements. It is foundthat the difference between the pull-out torques is even larger than calculatedfrom the model. Thereby, it can be concluded that the inter-bar currents havea considerable effect on motor starting performance.At rated speed the braking torques are larger in the aluminium rotor thanin the copper rotor. This is seen as increased harmonic joule losses in the rotorcage. Simulations have shown, that these losses can be as large as 1% ofthe output power for the studied machine.

QC20100617

Les composants magnétiques sont des constituants essentiels des convertisseurs électroniques de puissance en termes de volume et de coût, en particulier dans les alimentations à découpage. Pour cette raison, il est intéressant de développer des méthodes et des outils logiciels pour optimiser la conception de dispositif magnétiques en relation avec les paramètres de conversion. Concevoir et optimiser un composant magnétique suppose de définir parfaitement les contraintes induites par les spécifications, de choisir des conducteurs, isolants et circuits magnétiques, tant sur le plan des matériaux que des géométries, de calculer finement les pertes dans ces différentes parties et enfin, de disposer de modèles thermiques permettant de conduire le design en considérant la contrainte majeure que constituent les températures de fonctionnement des différentes parties du composant. L'objectif de cette thèse est de jeter les bases d'un outil générique d'aide à la conception optimale de composants magnétiques en s'appuyant sur des modélisations analytiques et numériques
The magnetic components are essential constituents of the power electronic converters in terms of volume and cost, particularly in switching power supplies. Therefore, it is essential to develop methods and software tools that can optimize the magnetic device design in relation to the conversion parameters. The design and optimization of the magnetic component includes several constraints that are imposed by the specifications including the choice of electrical conductors and magnetic circuits, both in terms of materials and their geometries. It is necessary to calculate the losses in these parts and to know the thermal models that allows a better design by considering the major constraint namely, the operation temperatures of different parts of the component.The current work describes the basics of a generic tool that will help in the optimal design of a magnetic components based on both analytical and numerical modeling

During the pyrometallurgical extraction of copper, a significant part of the copper is lost with discard slag, which decreases profits, overall copper recovery, and efficiency of raw material usage. Smelting furnace slag usually has a copper content that is close to or higher than that of copper ores. The investigation of copper losses to slag is thus a task of practical significance, as the ore grades are depleting. Slag cleaning, e.g., a settling furnace, can reduce copper losses to slag as the mechanically suspended copper-containing droplets separate from slag under the action of gravity and can hence be recovered.  An industrial trial was conducted in an electric settling furnace with slag originating from an electric smelting furnace and processed in a zinc fuming furnace. The trial was conducted to increase the understanding of copper losses to slag and how the process parameters temperature and settling time influence the slag copper content. The obtained slag samples were also evaluated to gain better insights as to the settling mechanism and, if any, factors that hinder the copper phases from settling. Slag modification with CaO was also evaluated to investigate how the modification influences the settling of copper phases and, thus, the final slag copper content.  Samples collected during the industrial trial were the basis for the evaluation in the current work. The samples came from batches with varying temperatures, settling times, and CaO content collected at four different sample positions. Instrumental techniques, including XRF, FAAS, ICP-SFMS, and SEM-EDS, were used to analyze the chemical compositions of the samples and the appearance of copper and associated phases.  The results indicated that the copper content of outgoing slag increased with increasing temperature in the evaluated interval. The copper content was also concluded to be more strongly affected by the temperature compared to the settling time. Regulating the temperature to the lower temperature interval in the settling furnace could thus decrease the final slag copper content. During the slag characterization, it was found that suspended copper-containing phases were hindered from settling, due to the attachment to solid phases and gas bubbles in the slag. By controlling and minimizing the presence of the bottom buildup and thus solid phases in the slag, the copper content can be decreased. The results indicated that the CaO slag modification decreased the final slag copper content, and can thus be used as a modifier for increased settling.

Le but de cette thèse est donc de mettre en œuvre la méthode µPEEC pour évaluer, sans avoir recours à des simulations ni à des mesures, la réluctance de circuits magnétiques simples en 2D et ce, afin de prédire leur comportement électromagnétique dès les phases de conception. Cela revient à chercher le champ créé par un brin conducteur rectiligne placé dans une fenêtre ronde ou rectangulaire de circuit magnétique comportant ou non un entrefer. Cette étude s'inscrit dans le cadre d'une recherche plus vaste, visant à élaborer le circuit équivalent de transformateurs, avant la réalisation de prototypes, afin d'optimiser ces composants au sein de leurs applications. Avant d'atteindre ce but, différentes étapes ont été franchies progressivement, en s'aidant de solutions analytiques et de simulations par éléments finis pour valider nos approches
The aim of this thesis is to implement the method μPEEC to assess, without using simulations or measurements, the reluctance of magnetic circuits and simple 2D to predict their behavior from electromagnetic design phases . It's just asking the field created by a blade straight conductor placed in a round window or rectangular magnetic circuit with or without an air gap. This study is part of a larger research aimed at developing the equivalent circuit of transformers, before prototyping to optimize these components in their applications. Before reaching this goal, several steps were taken gradually, with the help of analytical solutions and finite element simulations to validate our approaches

This thesis presents a study of inter-bar current effects on induction motors with die-cast aluminium and die-cast copper rotors. The parasitic effects introduced by these currents are analyzed and possible solutions to these problems are presented. This is realized by developing analytical tools for the simulation of inter-bar current effects. The methods used are verified by measurements on prototype machines. It is shown that the inter-bar currents can have a considerable effect on the motor starting performance, which can result in a reduced pull-out torque. At rated operation, this is seen as increased harmonic rotor currents, having a negative effect on the motor performance. Results from calorimetric measurements show, that the efficiency gained when substituting a skewed die-cast aluminium rotor with a skewed die-cast copper rotor, is less than the theoretical expectation. It is shown that this is a result of a reduced power factor for the copper rotor. High inter-bar currents are believed to be the origin of this effect, increasing the harmonic content in the rotor magnetomotive force. This would be seen as an increased rotor leakage reactance. Results from locked-rotor tests, and simulations using measured values of inter-bar resistance, support this theory. It is shown, that these negative effects are suppressed to a negligible level by the use of an unskewed rotor, but to the expense of a large synchronous torque at a low speed. By using a modulated rotor concept, having an asymmetrical rotor slot distribution, an unskewed rotor is designed to reduce this parasitic torque. Measurements on a prototype machine show that the modulated rotor suppresses both the inter-bar currents and the synchronous torque, resulting in an improved starting performance, without any significant change of the motor efficiency. The presented results strengthen the potential of the modulated rotor concept, introducing new possibilities for the reduction of negative effects appearing in induction machines.

QC 20130320

The master’s thesis Improvement power parameter of small induction motors deals with issues of lowering the losses of small induction motors. The first part introduces with design and principles of operation of induction motors. Also introduces to theoretical problematic of losses, their lowering and measuring. In the practical part there are results of the measuring the losses in the induction motor ATAS Elektromotory Náchod a.s. T22VT512 (71-0512). There are proposed methods of increasing the efficiency of induction motor due to measuring and their verification in the Maxwell software. The last part is dedicated to measuring the losses of prototype motor from ATAS and comparison of results with previous motor.

Classical series production induction motors are usually adequate to most of the industrial application by range of rpm. For application requiring higher speed is traditionally used gearbox which is between motor and driven equipment. Nowadays, where are settings demands on efficiency operations and the most easily maintainance, so aim is to join driven equipment narrow with motors. When operating motors over 3000 rpm there are some proper problems. Generally, there is higher losses due to supply voltage from frequency converters and mechanically strength of rotor. This thesis provides a view on existing solutions of high speed induction machines. In the text there are mentioned options of using laminated rotor and solid rotor. Due to regard to angular speed of rotor there are mentioned the most important equations and knowledge, which are related to a mechanical strength of used materials and dimensions of machines. Later on is there mentioned groundwork, which when we are respecting them, we may improve the efficiency of machine. In this thesis is mentioned design, analyses and manufacturing process of high speed induction motor with solid rotor and copper layer at the surface. After that there are simulation of electromagnetic field through the use of finite element method in program FEMM. In the last chapter there are presented measured data of manufactured high speed motor and they are compared with calculations.

L’amélioration énergétique des machines électriques est un sujet de plus en plus important,avec dans la décennie à venir, l’utilisation massive de machines électriques pourles transports. Au niveau des industries, les moteurs électriques sont responsables d’environ67% de la consommation de l’énergie électrique. Ce travail de thèse s’inscrit dansl’optique de l’amélioration énergétique des machines asynchrones qui sont prépondérantesdans le milieu industriel. Le travail présenté porte sur l’utilisation de deux technologiespour augmenter le rendement avec l’utilisation combiné d’un circuit magnétique à basede tôles grains orientés (GO) et de la technologie d’une cage d’écureuil en cuivre injectésous pression. En effet, l’utilisation d’un acier plus performant comparativementaux aciers classiquement utilisés permet une réduction des pertes fer. Le remplacementde l’aluminium injecté, qui est classiquement utilisé dans la fabrication des cages d’écureuils,par du cuivre permet une réduction importante des pertes Joule au rotor. Dans unpremier temps, l’impact du processus de l’injection du cuivre en fusion sur les propriétésmagnétiques des tôles GO a été déterminé. Le processus a tout d’abord été étudié pardes simulations numériques 2D et 3D afin de déterminer les températures au niveau del’acier magnétique. Ces températures ont été appliquées sur des bandes d’Epstein pourdéterminer l’influence de celles-ci sur les propriétés magnétiques. Dans un second temps,l’utilisation des tôles GO en champ tournant a été étudiée par une méthode expérimentaleet par une modélisation numérique afin de comprendre la complexité du trajet duflux magnétique dans une telle structure de circuit magnétique. L’utilisation de cettetechnologie a permis d’obtenir un gain non négligeable en termes de pertes notammentsur les pertes fer. Dans la dernière partie, différents prototypes de machines asynchronesont été testés afin d’apprécier l’apport de ces deux technologies permettant d’apprécierun gain important en termes d’efficacité énergétique grâce à une procédure expérimentale
Definition of high efficiency induction machine using die casting copper squirrel cageand grain oriented steel laminations Nowadays, increasing the efficiency of electrical motorshas become a priority in order to reduce electricity consumption. This thesis dealswith the study of an induction machine composed of a copper squirrel cage realized byhigh pressure die casting and a magnetic circuit made of grain oriented electrical steel(GO) in order to decrease Joule losses and core losses. In the first part, the impact ofthermal shock induced by the die casting copper process on the GO electrical steel wasstudied in order to validate the use of GO in rotor magnetic circuit. The temperatureoccurs during this kind of process has been modeled by 2D and 3D models. An experimentalprocess was realized on the standardize samples in order to make a comparisonwith and without annealing in terms of magnetic properties. In the second part, the newassembly method of magnetic circuit with GO electrical steel has been studied in orderto increase the benefits of use of GO steel in AC machines. The last part, a comparisonbetween several configurations of magnetic circuit in induction machine was realized inorder to confirm the gain of die casting copper rotor with GO electrical steel and GOstator magnetic circuit

This thesis deals with the problem of the high-speed induction machines. In the introduction the design of the machines and problem areas are discussed. The feeding from the frequency converter and the mechanical strength of the rotor appear to be the biggest problem. High-speed engines with solid rotors were designed. The first model is equipped with a conductive cooper layer on the surface. This model is exposed to harmonic and non-harmonic input voltage and then the results of the simulations are compared. The following model of the thesis is equipped with axial slots. In the practical part of the thesis no load measurement is taken. One point was measured at nominal frequency. At the end of the thesis the results of the measurements are compared with the results of the figures extracted from Maxwell software.

La machine à réluctance variable peut être utilisée dans les véhicules électriques où pour des considérations d’autonomie, le rendement est crucial. En raison du fort champ de fuite dans la région de l’entrefer de la machine à réluctance variable due à sa géométrie particulière à pôles saillants, les pertes « cuivre » peuvent devenir conséquentes. Il est alors recommandé de ne pas placer les conducteurs au voisinage de l’entrefer. Cependant, des instructions concrètes pour la conception d’un enroulement optimal sont manquantes. Généralement, les pertes « cuivre » dans les machines électriques sont la somme des pertes Ohm DC classiques et des pertes additionnelles dites par courants de Foucault. Les pertes DC étant constantes à un point de fonctionnement donné, l’optimisation est axée alors sur la réduction des pertes par courants de Foucault en jouant sur la configuration géométrique de l’enroulement. Dans le cas de calculs répétitifs fastidieux, rencontrés par exemple lors des processus de conception et d’optimisation du bobinage des machines électriques, il y a un intérêt significatif à réduire le temps de calcul. Dans ce travail, on présente trois techniques de réduction du modèle et leurs applications dans les analyses par la méthode des éléments finis. Outre l’influence de la fréquence d’alimentation et de la section du conducteur, plusieurs facteurs liés à la configuration de l’enroulement influent sur les pertes additionnelles par courants de Foucault :i) la position du conducteur dans l’encoche au voisinage de la dent du stator ou de la zone de l’entrefer .ii) la disposition des conducteurs envers les lignes du champ magnétique bidimensionnelles de l’encoche .iii) l’utilisation d’un conducteur massif ou multi filamentaire; les filaments sont connectés en parallèle et peuvent permuter leurs positions périodiquement au sein du conducteur tout au long du bobinage. Dans cette thèse, on étudie principalement l’influence de la disposition géométrique des spires dans l’encoche et du type du conducteur utilisé s’il s’agit d’un conducteur massif, en fils de Litz ou en fils torsadés. Les pertes par courants de Foucault sont la conséquence d’un couplage fort électrique-magnétique entre la densité du courant et la variation en fonction du temps du champ magnétique. En utilisant le modèle de Maxwell, ce couplage est décrit par une équation différentielle à dérivée partielle qui ne peut être résolue simplement. La résolution de cette équation utilisant l’approche analytique n’est possible que sous certaines hypothèses simplificatrices qui peuvent dégrader la fiabilité de la solution. La modélisation par la méthode des éléments finis permet quant à elle de prendre en compte le mouvement du rotor et la non-linéarité du circuit magnétique garantissant ainsi une meilleure précision. Néanmoins, cela conduit à une large capacité de stockage et à un temps de calcul substantiel qui peut entraver tout processus de conception ou d’optimisation. Pour surmonter ce problème, on propose dans ce manuscrit trois techniques de réduction du modèle. Ces techniques assurent une réduction efficace de la taille du système matriciel associé à la modélisation par la méthode des éléments finis et diminuent par conséquent le temps de calcul : i) une réduction spatiale qui évite une modélisation en 3D des conducteurs complexes en fils torsadés et en fils de Litz et propose une modélisation 2D satisfaisante .ii) la technique de la perturbation. iii) la réduction de l’ordre du modèle utilisant la méthode de la décomposition orthogonale aux valeurs propres combinée à la méthode d’interpolation empirique discrète. La comparaison du modèle réduit à un modèle complet de référence montre l’efficacité de la réduction du modèle à réduire le temps de calcul tout en restant en deçà d’une erreur de précision acceptable
The switched reluctance machine can be used in hybrid or electric vehicle where, for autonomy considerations, energy efficiency is crucial. Because of the strong stray field in the air-gap region of the switched reluctance machine due to its salient pole geometry, the copper losses can become substantial. It is firmly recommended therefore not to place the coil conductors near the air-gap region. Nevertheless, concrete instructions for optimal winding design are missing. The copper losses in electrical machines are subdivided into classical DC ohmic losses and additional eddy current losses occurring due to the time varying magnetic fields penetrating the copper conductors. Based on the fact that the DC losses are constant at a given operating point, the optimization is focused on reducing the eddy current losses by modifying the winding geometry configuration. In the case of tedious repetitive calculations, met for example during design and optimization processes of electrical machine windings, there is a significant interest in reducing the computation time. This work suggests three model reduction techniques and their applications in the finite element analyses.Besides the frequency of the excitation current and the cross section of the coil conductors, several factors related to the winding configuration can affect the addition al eddy current losses:i) the coil conductor position in the winding slot especially near the stator pole or close to the air gapii) the disposition of the coil conductor against the two-dimensional flux lines in the slot windingiii) the subdivision of the solid conductor into multiple parallel strands swapping their positions periodically in the conductor cross section throughout the length of the machine winding.This thesis mainly studies the influence of the geometric coils disposition in the slot windings and the type of the conductor used whether it is solid or stranded, with Litz or twisted wires.The eddy current losses exit through the strong electro-magnetic coupling between the electric current density and the time dependent magnetic flux lines penetrating the conductors; it is described mathematically by a partial differential equation that cannot be solved easily. The analytical approach, which is used practically for a quick resolution of the strong electro-magnetic coupling equation, is only possible under certain simplifying assumptions that deteriorate brutally the reliability of the copper losses calculation. The finite element modeling as for it, allows taking into account the rotor motion and the non-linear behavior of the magnetic circuit, thus ensuring a higher accuracy. However, it leads under these conditions to a substantial calculation time and requires large storage capacity. These constraints are critical and may hinder therefore any process of conception or optimization. In this thesis, we suggest three different model reduction techniques that can be effective in reducing the size of large scale complete finite element models and enable therefore to shorten the computational time:i) the spatial reduction avoiding the 3D modeling which seems required in the case of twisted and Litz wires and suggesting an alternative satisfactory 2D modeling.ii) the perturbation technique.iii) the model order reduction using the proper orthogonal decomposition combined with the discrete empirical interpolation method.The comparison between the reduced model solutions to that of the complete finite element model has proved the effectiveness of the proposed model reduction techniques; they allow shrinking the required computational time while staying below an acceptable error of accuracy

This work deal with troubleshooting of problem parts of high-speed induction machines. Introduction is about conception of induction machines with reference to construction specialities due to high rpm and because machines are fed by inverter. Next part is focused to design problems. A classical induction machine was measured to determination change of various losses in classic and high-speed induction machines. The computation of laboratory sample high-speed motor was specified for calculation of effective resistance and leakage reactance of solid-steel rotor with copper layer. The results of numerical calculation were validated by using finite elements method and machine design was adjusted for improving operation characteristic.

Les convertisseurs multicellulaires parallèles permettent de traiter des puissances importantes et de profiter d'une certaine standardisation des équipements. Ces dernières années, ces structures ont connu un regain d'intérêt lié notamment à la possibilité de couplage magnétique des inductances. Ce couplage aboutit à un composant magnétique aux propriétés très différentes appelé Transformateur Inter-Cellules (ICT) ; il ne modifie pas le courant de sortie, par contre il réduit l'ondulation de courant dans les bobines et l'ondulation de flux dans certaines parties du noyau. On peut montrer que ce couplage entraîne une réduction des pertes Joules dans les conducteurs et des pertes magnétiques dans le noyau. La réduction de l'ondulation de courant diminue également le courant efficace dans les semiconducteurs ce qui réduit les pertes par conduction, et la différence entre le courant à l'amorçage et au blocage des interrupteurs, ce qui permet la diminution des pertes dans les semiconducteurs lorsque les pertes au blocage sont supérieures aux pertes à l'amorçage. Le dimensionnement d'un ICT n'est pas fondamentalement différent de celui fait pour d'autres composants magnétiques en ce sens qu'il est basé sur le respect de certaines valeurs limites (induction, température) ce qui suppose une évaluation des différentes pertes et l'élaboration d'un modèle thermique. Par contre, la manière d'évaluer ces différentes grandeurs est tout à fait spécifique et n'a que quelques points communs avec les méthodes de calcul des inductances et des transformateurs Dans ce travail de thèse, on montre comment dimensionner ces ICTs en considérant plusieurs topologies et méthodes différentes, correspondant à différents niveaux de sophistication et de complexité. L'explication de ce dimensionnement est divisée en quatre parties : Pertes Cuivre, Pertes Fer, Densité de Flux de Saturation et Aspects Thermiques. L'évaluation des pertes cuivre liées aux composantes alternatives des ICTs constituent un point particulièrement délicat dans la mesure où elles résultent de la combinaison de deux facteurs eux-mêmes difficiles à évaluer ; l'inductance de fuite qui détermine l'amplitude des courants alternatifs mais dépend des flux principalement non canalisés et circulant dans l'air (volume d'étude important, effets 3D…), et la résistance équivalente des bobinages qui en haute fréquence est sujette à des phénomènes complexes comme les effets de peau et de proximité. En se basant sur l'utilisation d'un logiciel simple mais néanmoins robuste et fiable pour calculer précisément les résistances en haute fréquence et les inductances de fuite des ICTs, plusieurs astuces permettant de réduire les pertes cuivre non seulement des ICTs mais aussi des transformateurs et des inductances sont suggérées. Des tableaux simples sont développés pour aider le concepteur de transformateurs à identifier la meilleur configuration de conducteurs dans une fenêtre de bobinage en prenant en compte la forme d'onde du courant, le nombre de tours des enroulements, la fréquence des courants et les paramètres géométriques. Des formules analytiques et des outils de calcul adéquats ont ensuite été utilisés pour développer des routines d'optimisation ayant pour but la réduction de la masse, du volume, des pertes ou du coût des ICTs. Des interpolations multidimensionnelles des valeurs présimulées des résistances et inductances de fuite en haute fréquence sont utilisées afin de réduire le temps d'exécution de la routine d'optimisation. Plusieurs dimensionnements des ICTs ont été comparées vis-à-vis des matériaux du noyau et des conducteurs, du nombre de cellules de commutation et de la fréquence de découpage. Des comparaisons avec des selfs ont également été faites afin de montrer les avantages de ces ICTs. Des aspects de la commande des convertisseurs multi-niveaux triphasés ont également été étudiés vis-à- is du flux circulant dans les ICTs. Des homopolaires, spécifiques pour chaque stratégie MLI et chaque topologie convertisseur/charge, sont créées afin de minimiser le flux dans les ICTs et par conséquent de réduire davantage la masse et la taille de ces composants. Des comparaisons entre différentes méthodes de MLI sont effectuées et vérifiées expérimentalement
In recent years, the interest for parallel multicell converters has grown, which is partially due to the possibility of coupling the inductors used to connect the different commutation cells together. Coupling the inductors to form an InterCell Transformer (ICT) does not usually modify the output current, but it reduces the current ripple in the windings and the flux swing in some regions of the core. It can be shown that this brings a reduction of copper and core losses in the magnetic component. The reduction of the phase current ripple also reduces the difference between turn on and turn off current in the switches, which brings a reduction of switching losses for devices generating more losses at turn off than at turn on. The design of an ICT is not that different from any other magnetic component but it is very specific and inherent features must be taken into account. Taking full benefit of the potential advantages of ICTs requires the development of special tools and methods which are the focus of the study. We show how to design ICTs considering several topologies and different methods, from the most precise and time-consuming to the less accurate but more quickly calculated. The explanation of the ICT design is divided in four main parts: Copper Losses, Core Losses, Flux Density Saturation and Thermal Aspects. Further attention is given to high frequency copper losses since complex phenomena such as skin and proximity effects highly influence the ICT design. Based on Finite Element Method simulations, smart practices are suggested to reduce high and low frequency copper losses, not only in ICTs but also in inductors and transformers. Simple tables are developed to help transformer designers to identify the best configuration of conductors inside a given core window, depending on the current waveform and frequency, number of turns and geometrical parameters. Optimization routines to reduce the ICT total mass, volume, losses or cost are developed and multidimensional interpolation of pre-simulated values of AC resistance and leakage inductance is used to speed up the optimization routine. Comparison of ICT designs with regard to core and conductor material, number of cells and switching frequency is performed. Comparison with regular inductors is also made in order to verify the benefits of this kind of magnetic component. Multilevel converter control aspects applied to three- hase systems is also investigated in terms of the ICT flux. Zero sequence signals, specific for a PWM strategy and converter/load topology, are created in order to minimize the flux in ICTs and consequently reduce even further the mass and size of these components. Comparison between several PWM methods are performed and experimentally verified

University of Central Florida College of Engineering Thesis
The objectives of this research were to quantify formaldehyde consumption due to plating and parasitic reactions and determine the magnitude and distribution of formaldehyde losses from the electroless copper plating process. Plating and rinse bath samples obtained from three electroless copper plating operations were analyzed for formaldehyde and copper in order to develop a mass balance analysis about the plating bath for periods of active production and no production. Fugitive air and stack releases of formaldehyde were estimated using emission factors developed from air sampling at the three facilities. It was determined that approximately 90% of the formaldehyde added to the plating process was sonsumed by some type of chemical reaction. The remaining 10% of formaldehyde represents losses from the plating operation. For the facilities with a waste plating solution stream, atmospheric losses accounted for approximately 25% of the total losses. The mass of fugitive air formaldehyde measured approximately 2.8 times that escaping through the stack. Dragout accounted for approximately 2.3% of the losses with the remaining going to the waste stream. For the facility without a plating solution waste stream, formaldehyde losses were distributed 59% to atmospheric relases and 41% to the rinse tank. Fugitive and stack releases were approximately the same at 29% of the formaldehyde losses. Formaldehyde consumption due to parasitic reactions for periods of active plating and no plating were determined for two facilities. The rate of parasitic consumption during periods of production was found to be approximately 3 times greater than that for no production. The rate of parasitic consumption was observed to increase with increasing bath temperature.
M.S.;
Civil and Environmental Engineering;
Engineering;
Environmental Engineering;
206 p.
xii, 206 leaves, bound : ill. ; 28 cm.

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper and copper-, based alloys for more than 40 years. It has been successfully employed for the, prevention of both atmospheric corrosion and particularly for the protection of, copper under immersed conditions. Whilst BTAH is an excellent inhibitor in alkaline, solution its efficiency drops off markedly as the pH decreases. It was hypothesized, that a possible way to increase surface adsorption and subsequent better inhibition, over a wide pH range might be through the preparation of derivatives, particularly, carboxybenzotriazoles and alkyl esters of these compounds. In this work the following techniques: weight loss measurements, potentiodynamic, polarisation, SERS spectroscopy, electrochemical impedance spectroscopy and, coulometry were employed to investigate the inhibition efficiency of 4- and 5-, carboxybenzotriazole and their alkyl ester for copper corrosion. Molecular modelling, was also investigated as a tool for inhibitor design. Studies on 4- and 5- carboxybenzotriazole (CBT) showed that the inhibition, efficiency for copper corrosion in aerated acidic sulphate solution of each isomer was, pH, concentration and time dependant. At lower pH the 5-isomer is the better, inhibitor and this behaviour continues at higher pH. The anti-tarnishing test showed, that whilst both isomers exhibited these properties, 5-CBT was once again the, superior inhibitor. It was found that a commercial mixture of the octyl esters of 4- and 5-, carboxybenzotriazole inhibits copper corrosion in sulphate environments open to air., The inhibition efficiency of the ester mixture at the lx10-4 M level (pH - 0) is 98%, which compares very favourably with that for BTAH (- 50%). With respect to other, alkyl esters of 4- and 5-carboxybezotriazole, hexyl, butyl and methyl, it was found, that all of these inlibited copper corrosion in sulphate environments open to air. In, each case the inhibition efficiency is concentration, pH and time dependent. Both, coupon tests and EIS measurements indicate that inhibition efficiency depends on the, length of the alkyl chain. At pH - 0 the inhibition efficiency decreased in the order, octyl >hexyl >butyl >methyl. At higher pH (- 8) the order is reversed. At the 1x104, M level (pH - 0) the inhibition efficiency of each of the alkyl esters is equal to or, better than that for BTAH. At higher pH (- 8) the inhibition efficiency in each case is, reduced in comparison to BTAH. but is still good enough for practical use ( 2 75%)., The inhibitive behaviour of the alkyl esters at low pH can be attributed to, chemisorption through an azole nitrogen of the protonated alkyl esters. The, hydrocarbon chain is also physically adsorbed and the increase in physical adsorption, as the chain is lengthened accounts for the improved inhibition efficiency. Dry films formed by immersing copper in solutions of alkyl esters of, carboxybenzotriazole also inhibit copper corrosion in both strongly acidic (pH - 0), and near neutral (pH - S) sulphate corrodents. The inhibition efficiency depends on, the solvents used to dissolve the esters, solution temperature and immersion time., Aqueous coating solutions furnish the most protective films. Films formed by, CBTAH-BU, CBTAH-HE and CBTAH-OE are more protective than that formed by, BTAH. The inhibition efficiency of the alkyl ester film increases as the alkyl chain is, made longer. Molecular modeling showed that the optimum crude binding energy (Eblnd), between each protonated ester molecule and the surface varied linearly with the alkyl, chain length. The resulting linear correlation between IE% and E bind for compounds, that are structurally similar suggested that the crude binding energy of a single, molecule with copper may be used to predict the inhibition performance of other, compounds constituting a series.

The major contributions of this thesis are categorized into three areas: (i) magnetic modeling, (ii) optimal performance assessment and (iii) multi-objective design methodology of the linear permanent-magnet (LPM) and linear variable reluctance (LVR) motors for manufacturing automation applications. The target application is to perform repetitive point-to-point positioning tasks on a continuous basis under temperature constraints. Through simplification, the constraint on temperature rise may be replaced by a constraint on average power dissipation, provided that the thermal resistance is constant and known. The basic framework of analysis is first introduced for a class of idealized linear synchronous (LS) motors, where magnetic saturation and spatial harmonics are neglected, to provide clarity and insight. The physics-based force models for the LPM and LVR motors, including spatial harmonics and magnetic saturation as appropriate, are then developed. Due to magnetic linearity, the force model of the LPM motor is derived from the analytical solution of the Poisson Equation. A nonlinear magnetic circuit analysis model is developed for the LVR motor that includes both spatial harmonics and magnetic saturation. The accuracy of both force models are verified by finite element analysis. Applying those force models, the optimal performance assessment of the LPM and LVR motors is explored using the mathematical framework discussed for the idealized LS motors. In particular, the relationship between travel time and travel distance is characterized in terms of average power dissipation. The performance assessment methodologies developed here may be applied to any motor technology used in manufacturing automation applications. The multi-objective design optimization problem is then defined and software for its solution is developed using Monte-Carlo synthesis, the performance assessment tools and dominance-based sorting. Design results for the LPM and LVR motors are then presented. Future research is discussed as the conclusion of the thesis.

Ok Tedi Mining Limited generates a copper and gold concentrate from its porphyry and skarn ore deposits located at Mt. Fublian, Western Province, PNG. The predominant porphyry ore-type is blended with high grade skarn ores to optimize copper and gold feed grades to the concentrator. Current operation (2003) is to blend 80% porphyry with 20% skarn ores, resulting in an acceptable concentrate grade and recovery. However, when the proportion of skarn ore in the plant feed exceeds 20%, low flotation recovery is often observed. Approximately 20% of the copper and 30% gold losses occur through the rougher flotation circuit. However, losses via the cleaner tailing stream are 8% and 9% for copper and gold, respectively, and augment value mineral losses to the final tailing. It may be noted that the cleaner tailing stream contains value minerals which have already been successfully floated in the rougher section of the concentrator, and are therefore recoverable. This study has the objective of determining the reasons for copper and gold loss in the cleaner tailing. The focus is therefore on the cleaner flotation bank and related streams. The project strategy commenced with characterization of the cleaner circuit performance under various operating conditions. This would provide evidence for any proposed mechanisms to explain the losses of valuable minerals to the cleaner tailing. The second part of the project strategy was to evaluate potential methods for improvement of cleaner flotation performance via laboratory flotation tests. To complete the work, plant trials of methods showing benefit in the laboratory were conducted.
Characterisation surveys of the cleaner flotation bank were conducted as a function of ore blend, pulp and surface chemistry, mineralogy, flotation kinetics, particle size distribution, cleaner flotation cell hydrodynamic characterisation and residence time. These studies indicated that for greater than 20% pyrite skarn in the concentrator feed blend, lower than expected gold and copper recoveries were achieved in the cleaner bank. Pulp and surface chemical analytical techniques indicated layers of oxide coatings existed on all particles, depressing flotation. Oxide coatings had also resulted in the copper activation of pyrite (CuS rimming), making separation from copper sulfides difficult. Losses included coarse composite particles, also suggesting possible liberation issues. However, liberated copper sulfides were also lost, supporting the notion of depression via oxide coatings. Residence time calculations for the cleaner flotation bank suggested that the flotation capacity was less than adequate, particularly at high mill throughput rates. Hydrodynamic characterisation indicated improvements in cell hydrodynamics were warranted. In contrast to the oxidised ore feed blend described above, when less than 20% pyrite skarn was contained in the ore blend, high copper and gold recoveries were achieved in the cleaner bank. Laboratory tests suggested that increasing cleaner feed pH from 10.5 to 11.5, and 1 or collector addition to the cleaner feed, would result in improved cleaner flotation performance. These changes were trialed in the plant, with the pH adjustment being successful. High cleaner feed pH continues as a permanent modification to plant operating conditions.

The thermal atomic layer deposition (ALD) of copper oxide films from the non-fluorinated yet liquid precursor bis(tri-n-butylphosphane)copper(I)acetylacetonate, [(ⁿBu₃P)₂Cu(acac)], and wet O₂ on Ta, TaN, Ru and SiO₂ substrates at temperatures of < 160°C is reported. Typical temperature-independent growth was observed at least up to 125°C with a growth-per-cycle of ~ 0.1 Å for the metallic substrates and an ALD window extending down to 100°C for Ru. On SiO₂ and TaN the ALD window was observed between 110 and 125°C, with saturated growth shown on TaN still at 135°C. Precursor self-decomposition in a chemical vapor deposition mode led to bi-modal growth on Ta, resulting in the parallel formation of continuous films and isolated clusters. This effect was not observed on TaN up to about 130°C and neither on Ru or SiO₂ for any processing temperature. The degree of nitridation of the tantalum nitride underlayers considerably influenced the film growth. With excellent adhesion of the ALD films on all substrates studied, the results are a promising basis for Cu seed layer ALD applicable to electrochemical Cu metallization in interconnects of ultralarge-scale integrated circuits. © 2009 The Electrochemical Society. All rights reserved.
Es wird die thermische Atomlagenabscheidung (ALD) von Kupferoxidschichten, ausgehend von der unfluorierten, flüssigen Vorstufenverbindung Bis(tri-n-butylphosphan)kupfer(I)acetylacetonat, [(ⁿBu₃P)₂Cu(acac)], sowie feuchtem Sauerstoff, auf Ta-, TaN-, Ru- und SiO₂-Substraten bei Temperaturen < 160°C berichtet. Typisches temperaturunabhängiges Wachstum wurde zumindest bis 125°C beobachtet. Damit verbunden wurde für die metallischen Substrate ein Zyklenwachstum von ca. 0.1 Å erzielt sowie ein ALD-Fenster, das für Ru bis zu einer Temperatur von 100°C reicht. Auf SiO₂ und TaN wurde das ALD-Fenster zwischen 110 und 125°C beobachtet, wobei auch bei 135°C noch gesättigtes Wachstum auf TaN gezeigt werden konnte. Die selbständige Zersetzung des Precursors ähnlich der chemischen Gasphasenabscheidung führte zu einem bimodalen Schichtwachstum auf Ta, wodurch gleichzeitig geschlossene Schichten und voneinander isolierte Cluster gebildet wurden. Dieser Effekt wurde auf TaN bis zu einer Temperatur von 130°C nicht beobachtet. Ebensowenig trat er im untersuchten Temperaturbereich auf Ru oder SiO₂ auf. Der Nitrierungsgrad der TaN-Schichten beeinflusste hierbei das Schichtwachstum stark. Mit einer sehr guten Haftung der ALD-Schichten auf allen untersuchten Substratmaterialien erscheinen die Ergebnisse vielversprechend für die ALD von Kupferstartschichten, die für die elektrochemische Kupfermetallisierung in Leitbahnsystemen ultrahochintegrierter Schaltkreise anwendbar sind

This thesis reports on a new implementation of high quality factor (Q) copper (Cu) inductors on CMOS-grade (10-20ohm.cm) silicon (Si) substrates using a fully CMOS-compatible process. A low-temperature (less than300C) fabrication sequence is employed to reduce the loss of Si wafers at RF frequencies by trenching the Si substrate. The high aspect-ratio (30:1) trenches are subsequently bridged over or refilled with a low-loss material to close the open areas and to create a rigid low-loss island (Trenched Si Island) on which the inductors can be fabricated. The method reported here does not require air suspension of the inductors, resulting in mechanically-robust structures that are compatible with any packaging technology. The metal loss of inductors is reduced by electroplating thick (~20m) Cu layer. Fabricated inductors are characterized and modeled from S-parameter measurement. Measurement results are in good agreement with SONNET electromagnetic simulations. A one-turn 0.8nH Cu inductor fabricated on a Trenched Silicon Island (TSI) exhibits high Q of 71 at 8.75 GHz. Whereas, the identical inductor fabricated on a 20um thick silicon dioxide (SiO2) coated standard Si substrate has a maximum Q of 41 at 1.95GHz. Comparing the Q of inductors on TSI with that of other micromachined Si substrates reveals the significant effect of trenching the Si in reduction of the substrate loss. This thesis outlines the design, fabrication, characterization and modeling of spiral type Cu inductors on the TSIs.

Forskning om entreprenörskap fokuserar på framgång som ignorerar den höga felfrekvensen av Nya företag. Många nya företag misslyckas så hur entreprenörer hantera det när deras företag misslyckas? Framgångsrika entreprenörer prisar fördelarna med misslyckande som en värdefull lärare. Resultatet av misslyckande regelbundet fylld med ekonomiska, sociala, psykologiska och fysiska hälsoproblem. Syftet med denna forskning är att bedöma företagets misslyckande upplevelser för företagare, från det ögonblick resultatet genom att  återhämtningen för att hantera företagande fel och avsluta för påverkan av den slutna företag.  I denna forskning aspekter av livet som påverka av entreprenörs fel undersöka ekonomiskt, socialt och psykologiskt att belysa faktorer som kan påverka mängden av kostnaderna för ett misslyckande. Därefter beskriver forskningen hur entreprenörer lära av misslyckanden. Den presenterar på resultaten av företagets misslyckande, inklusive hantera fel och återhämtning tillsammans med kognitiva och beteendemässiga utfall.
Research on entrepreneurship focuses on success which ignores the high failure rate of new ventures. Many new ventures fail so how entrepreneurs deal with it when their venture    fails? Successful entrepreneurs praising the advantages of failure as a valuable teacher. The result of failure is regularly filled with economic, social, psychological, and physical health disorder. The aim of this research is to assessment venture failure experiences for entrepreneurs, from the instant result through to recovery for coping with entrepreneurial failure and exit for impact of the closed venture. In this research, aspects of life affected by entrepreneurial failure examine economically, socially and psychologically in highlighting factors that may influence the amount of costs of failure. Next, the research describes how entrepreneurs learn from failure. It presents on the outcomes of venture failure, including coping with failure and recovery together with cognitive and behavioral outcomes. The main objective of the research study is to understand the failure from entrepreneurs    who have experienced it and also to make a theoretical framework of failure based on entrepreneurial venture failure experiences. Every entrepreneur starts up a venture with high expectations of achieving success. Failure can be emotionally disturbing, devastating,  painful, distressing and costly for the entrepreneur who may have to aspect the stigma of failure and the loss of reputation. The entrepreneur can get involved in grief, heartache, anxiety, depression, shame, rejection and discouragement (Politis & Gabrielsson, 2009). The purpose of the research is to investigate how entrepreneurs realize and react to venture  failure. Moreover, entrepreneurs are looking for positive aspects of failure as enhancing experiences that help their coping with entrepreneurial failure, learning from failure, the willingness to begin a new venture and also trigger changes in upcoming decision-making. The purpose of the research is to take a view of the existed experience of failure, taking into consideration impact from the entrepreneurship.

Research on entrepreneurship focuses on success which ignores the high failure rate of new ventures. Many new ventures fail so how entrepreneurs deal with it when their venture fails? Successful entrepreneurs praising the advantages of failure as a valuable teacher. The result of failure is regularly filled with economic, social, psychological, and physical health disorder. The aim of this research is to assessment venture failure experiences for entrepreneurs, from the instant result through to recovery for coping with entrepreneurial failure and exit for impact of the closed venture. In this research, aspects of life affected by entrepreneurial failure examine economically, socially and psychologically in highlighting factors that may influence the amount of costs of failure. Next, the research describes how entrepreneurs learn from failure. It presents on the outcomes of venture failure, including coping with failure and recovery together with cognitive and behavioral outcomes. The main objective of the research study is to understand the failure from entrepreneurs who have experienced it and also to make a theoretical framework of failure based on entrepreneurial venture failure experiences. Every entrepreneur starts up a venture with high expectations of achieving success. Failure can be emotionally disturbing, devastating, painful, distressing and costly for the entrepreneur who may have to aspect the stigma of failure and the loss of reputation. The entrepreneur can get involved in grief, heartache, anxiety, depression, shame, rejection and discouragement (Politis & Gabrielsson, 2009). The purpose of the research is to investigate how entrepreneurs realize and react to venture failure. Moreover, entrepreneurs are looking for positive aspects of failure as enhancing experiences that help their coping with entrepreneurial failure, learning from failure, the willingness to begin a new venture and also trigger changes in upcoming decision-making. The purpose of the research is to take a view of the existed experience of failure, taking into consideration impact from the entrepreneurship.
Forskning om entreprenörskap fokuserar på framgång som ignorerar den höga felfrekvensen av nya företag. Många nya företag misslyckas så hur entreprenörer hantera det när deras företag misslyckas? Framgångsrika entreprenörer prisar fördelarna med misslyckande som en värdefull lärare. Resultatet av misslyckande regelbundet fylld med ekonomiska, sociala, psykologiska och fysiska hälsoproblem. Syftet med denna forskning är att bedöma företagets misslyckande upplevelser för företagare, från det ögonblick resultatet genom att återhämtningen för att hantera företagande fel och avsluta för påverkan av den slutna företag. I denna forskning aspekter av livet som påverkas av entreprenörs fel undersöka ekonomiskt, socialt och psykologiskt att belysa faktorer som kan påverka mängden av kostnaderna för ett misslyckande. Därefter beskriver forskningen hur entreprenörer lära av misslyckanden. Den presenterar på resultaten av företagets misslyckande, inklusive hantera fel och återhämtning tillsammans med kognitiva och beteendemässiga utfall.

In recent years, the interest for parallel multicell converters has grown, which is partially due to the possibility of coupling the inductors used to connect the different commutation cells together. Coupling the inductors to form an InterCell Transformer (ICT) does not usually modify the output current, but it reduces the current ripple in the windings and the flux swing in some regions of the core. It can be shown that this brings a reduction of copper and core losses in the magnetic component. The reduction of the phase current ripple also reduces the difference between turn on and turn off current in the switches, which brings a reduction of switching losses for devices generating more losses at turn off than at turn on. The design of an ICT is not that different from any other magnetic component but it is very specific and inherent features must be taken into account. Taking full benefit of the potential advantages of ICTs requires the development of special tools and methods which are the focus of the study. We show how to design ICTs considering several topologies and different methods, from the most precise and time-consuming to the less accurate but more quickly calculated. The explanation of the ICT design is divided in four main parts: Copper Losses, Core Losses, Flux Density Saturation and Thermal Aspects. Further attention is given to high frequency copper losses since complex phenomena such as skin and proximity effects highly influence the ICT design. Based on Finite Element Method simulations, smart practices are suggested to reduce high and low frequency copper losses, not only in ICTs but also in inductors and transformers. Simple tables are developed to help transformer designers to identify the best configuration of conductors inside a given core window, depending on the current waveform and frequency, number of turns and geometrical parameters. Optimization routines to reduce the ICT total mass, volume, losses or cost are developed and multidimensional interpolation of pre-simulated values of AC resistance and leakage inductance is used to speed up the optimization routine. Comparison of ICT designs with regard to core and conductor material, number of cells and switching frequency is performed. Comparison with regular inductors is also made in order to verify the benefits of this kind of magnetic component. Multilevel converter control aspects applied to three- hase systems is also investigated in terms of the ICT flux. Zero sequence signals, specific for a PWM strategy and converter/load topology, are created in order to minimize the flux in ICTs and consequently reduce even further the mass and size of these components. Comparison between several PWM methods are performed and experimentally verified.

Στις ηλεκτρικές μηχανές ο υπολογισμός των απωλειών και οι μηχανισμοί που τις προκαλούν αποτελούν ένα πολύ απαιτητικό αντικείμενο μελέτης. Τα τελευταία χρόνια καθώς αυξάνεται η ανάγκη για ολοένα και πιο αποδοτικές μηχανές μεγάλο κομμάτι της έρευνας έχει επικεντρωθεί στον υπολογισμό των απωλειών τους και πιο συγκεκριμένα στον υπολογισμό των απωλειών σιδήρου. Οι απώλειες σιδήρου ή αλλιώς απώλειες πυρήνα αποτελούν σημαντικό μέρος των απωλειών μια μηχανής, ταυτόχρονα όμως ο υπολογισμός τους εμφανίζει ιδιαίτερη δυσκολία. Στην παρόυσα διπλωματική εργασία η προσπάθεια επικεντρωνεται στον υπολογισμό αυτών των απωλειών σε μια ασύγχρονη μηχανή με διάφορες μεθόδους. Πιο συγκεκριμένα, στο πρώτο κεφάλαιο γίνεται μια εισαγωγή στα σιδηρομαγνητικά υλικά και στις ιδιότητες τους. Αρχικά παρουσιάζεται το φαινόμενο της μαγνήτισης και του κορεσμού. Στη συνέχεια μελετάται το φαινόμενο της υστέρησης και οι ιδιότητες της που παίζουν καθοριστικό ρόλο στις απώλειες του πυρήνα της μηχανής, αλλά και το φαινόμενο των δινορευμάτων. Στο δεύτερο κεφάλαιο μελετώνται οι απώλειες της μηχανής. Με ποιό τρόπο δηλαδή το φαινόμενο της υστέρησης και των δινορευμάτων πρoκαλούν απώλειες στη μηχανή και με ποια μορφή εμφανίζονται. Παρουσιάζονται ακόμα οι μηχανισμοί που συνδέονται με τις απώλειες χαλκού, επιδερμικό φαινόμενο και φαινόμενο γειτνίασης και ο ρόλος τους. Παρουσιάζεται επίσης μια βιβλιογραφική έρευνα σχετικά με τις διάφορες μεθόδους που χρησιμοποιούνται για τον υπολογισμό των απωλειών σιδήρου. Το τρίτο κεφάλαιο αποτελεί ουσιαστικά μια εισαγωγή στα ηλεκτρονικά ισχύος και πιο συγκεκριμένα στον αντιστροφέα τάσης με τεχνική PWM. Σημαντικός θεωρείται ο τρόπος με τον οποίο διαμορφώνεται η τάση εισόδου στη μηχανή, αλλά και η μορφή της, καθώς επηρεάζει άμεσα τις απώλειες σιδήρου της μηχανής. Στο τέταρτο και τελευταίο κεφάλαιο βρίσκουν εφαρμογή όλα τα παραπάνω. Η εργασία γίνεται με τη βοήθεια ενός μοντέλου πεπερασμένων στοιχείων, δύο διαστάσεων, μιας ασύγχρονης μηχανής βραχυκυκλωμένου κλωβού. Αρχικά η μηχανή τροφοδοτείται από μια ημιτονοειδή τάση είσόδου. Υπολογίζονται οι απώλειες χαλκού και στη συνέχεια οι απώλειες σιδήρου με τη βοήθεια υπολογιστικών μεθόδων ανάλυσης του μαγνητικού πεδίου σε σειρές Fourier. Τέλος μελετάται η μορφή του μαγνητικού πεδίου σε διάφορα σημεία της μηχανής και οι απώλειες που εμφανίζεται σε κάθε στοιχείο του μοντέλου ανά περίπτωση. Τα βήματα αυτά επαναλαμβανονται τροφοδοτώντας αυτή τη φορά τη μηχανή μέσω αντιστροφέα τάσης με τεχνική PWM. Συγκρίνοντας τα αποτελέσματα από κάθε περίπτωση εξάγονται σημαντικά συμπεράσματα για τις απώλειες της μηχανής και τη συμπεριφορά των μηχανισμών που τις προκαλούν.
In electrical machines the calculation of loss and the mechanisms that cause them are a very demanding subject of study. Recently, the increasing need for ever more efficient machines has made the research focus on the calculation of their losses and more specifically the calculation of the iron losses. The iron losses or core losses, constitute an important part of the total machine losses, but also their calculation is particularly difficult. In this thesis we focus on the calculation of these losses in an asynchronous machine using various methods. More specifically, the first chapter is an introduction to the properties of ferromagnetic materials. First, we study the phenomenon of magnetization and saturation and then we examine the phenomenon of hysteresis and its properties which play a crucial role in the core losses of the machine. Finally we study eddy current phenomenon. In the second chapter we discuss the losses of the machine. In which way the phenomenon of hysteresis and eddy currents generate losses in the machine and the form in which they appear. Also presented are the mechanisms associated with the copper losses, skin effect and proximity effect. Also shown is a literature survey on various methods used to calculate the iron losses. The third chapter is essentially an introduction to power electronics, and more particularly to the PWM technique. Important in this chapter is the way in which the input voltage to the machine affects the iron losses. In the fourth and final chapter we produce results of the above theory using simulation methods. The work is done using a finite element model in two dimensions of a squirrel cage asynchronous machine. Initially the machine is fed by a sinusoidal input voltage. Firstly copper losses are calculated and then the iron losses with the help of computational methods which analyze the magnetic induction in Fourier series. Finally, we study the shape of the magnetic field in different parts of the machine and the losses occurring in each element of the model in each case. These additional losses are known as rotational core losses. These steps are repeated, this time powering the machine via inverter supply using the PWM technique.

This work resulted in one oral presentation and two publications: Paper accepted for presentation and publication, Colóquio em Investigações em Conservação do Património, “Arte e Ciência: Investigação sobre a técnica e materiais aplicados na pintura sobre cobre”, Daniel Vega, Isabel Pombo Cardoso and Leslie Carlyle. Faculdade de Belas Artes da Universidade de Lisboa (FBAUL), Lisbon. Paper accepted for publication, International Symposium Paintings on copper (and other metal plates). Production, degradation and conservation issues, “Investigation and testing to develop an infill formula suitable for oil paintings on copper”, Daniel Vega, Isabel Pombo Cardoso and Leslie Carlyle. Universitat Politècnica de València (UPV), Valencia, Espanha.
The present work is divided in two parts. Part 1 concentrates on the study of the manufacture of copper plates used as a support for oil paintings since to date, there has not been a great deal of information available. The research involved comparing the information gathered from historical treatises on metallurgy and recent studies of paintings on copper and copper archaeometallurgy, with results from a set of thorough scientific analyses undertaken on the copper supports of fifteen European paintings (dating from the 17th and 18th centuries). This comparison revealed interesting insights into the metallurgic processes used to produce the copper ingot from native copper, and the subsequent manufacturing processes undertaken to obtain the copper plates. Copper ore purification was a complex and expensive process. Purification included several steps, all of which were rigorously executed as attested by the high level of purity of the copper produced. Scientific analyses undertaken on the copper supports of the fifteen European paintings revealed that the manufacture of the plates from the ingots involved cycles of cold working alternating with annealing. Hammering took place which would have been aimed to form a plate with adequate hardness, while the intermediate stage of annealing returned malleability so that further intense cold work, necessary to achieve a plate without breaking, could be carried out. Part 2 focus on the characterization of two wax-resins formulations used as infill materials for oil paintings: a formula used by Carlyle in the early 1980s (C-PWR) and Gamblin pigmented wax-resin (G-PWR). and, based on the negative impact on copper of the acidic beeswax in both formulations, an exploration to find a new formulation with a neutral acid value was carried out. Preliminary trials and testing focussed on the development of a new wax-resin formulation suitable for infills on oil paintings with a copper substrate. New options for infill materials on copper supports are particularly important as the range of infill materials currently available are not suitable, for a variety of reasons, for use on this type of support. Although ageing tests are still needed, the characterization of the individual materials, and of the new formulation, KTW5-R1, made of Techniwax 9426 microcrystalline wax with Regalrez 1094, showed that this wax resin mixture with an acid number of 0, is likely to be inert in relation to the copper and chemically stable since it is composed of saturated hydrocarbons only.

碩士
國立臺灣大學
電機工程學研究所
100
The main purpose of this thesis is to examine how the rotor current affects the output power and loss of a doubly-fed induction generator (DFIG) for wind energy conversion. The performance of the DFIG with and without copper loss minimization was investigated. In the experiment, feedback signals derived from the servo motor were first employed to calculate rotor angle which was essential for stator flux estimation. Then, the real and reactive power outputs of the DFIG were controlled by a rotor side inverter using a PI controller and the pulse width modulation (PWM) technology. Both experimental results and simulation results for DFIG with maximum power point tracking and copper loss minimization were presented. It was found from the results that less copper loss and more output power could be achieved by the copper loss minimization algorithm.

Hydrogen quantum state resolved energy losses upon scattering from copper are studied using molecular beam techniques and quantum state-specific detection methods. Also clean copper and hydrogen and oxygen covered copper surfaces were studied using electron spectroscopy. There are many questions about the nature of molecule-surface dynamics and the processes. The relative role of the different degrees of freedom in the reaction and the importance of non-adiabatic effects have been two of these questions. These two questions motivated this work. Energy loss in the elastic scattering of H₂(v=1. J=1) and H₂(v=0, J=1) molecular quantum states is measured as a function of incident translational energy at two surface temperatures. The energy loss process is shown to agree to the Baule classical model for energy ranges 74-150 meV for the excited vibrationally state and 74-125 for the ground vibrational state. Results suggest that translational energy is more effective that vibrational energy in the observed process. Theoretical models have been able to explain several processes using nonadiabatic models where friction coefficient tensor is included. Results in this thesis suggest that the energy loss in the elastic scattering is a nonadiabatic one. Electron spectroscopy studies showed that the surface plasmon intensity is very sensitive to surface contamination. Using this property, surface-only sensitive virtual temperature programmed desorption (VTPD) is developed. A better understanding of unique behavior of hydrogen covered Cu(100) was gained.
text

Copper exposure is known to be a rare cause of skin irritation and allergic reactions and according to our knowledge occupational dermal exposure to copper sulphate has not yet been characterised. As a result, the objectives of this study were to assess the dermal exposure of workers at a chemical industry to copper sulphate and to characterise the change in the their skin barrier function from before to the end of the work shift, as the skin’s barrier function can greatly influence the permeation of chemical substances. Methods: The change in skin barrier function of reactor workers, crystal and powder packaging workers at the chemical industry were assessed by measuring their dominant hand’s palm, back and wrist as well as their foreheads’ skin hydration, transepidermal water loss (TEWL) and skin surface pH before and at the end of the work shift. Commercial GhostwipesTM were used to collect dermal exposure samples from the same four anatomical areas before and at the end of the shift. Additional dermal exposure samples were collected from the palm and back of hand, prior to breaks 1 and 2. Surface wipe sampling was also conducted at several work and recreational areas of the chemical industry. Wipe samples were analysed by an accredited analytical laboratory, according to NIOSH method 9102 by means of Inductively Coupled Plasma-Atomic Emission Spectrometry. Results: Changes in skin hydration of the workers and anatomical areas at the end of the work shift were highly variable, while in general TEWL increased and skin surface pH decreased. Copper was collected from the skin of all workers before the shift commenced, and dermal exposure increased throughout the work shift. All of the work and recreational areas from which surface samples were taken, were contaminated with copper. Conclusion: As a result of intermittent use of inadequate protective gloves and secondary skin contact with contaminated surfaces and work clothing, workers at the chemical industry are exposed to copper sulphate via the dermal exposure route. The decrease in the workers’ skin barrier function (increased TEWL) and skin surface pH is most likely the result of their dermal exposure to sulphuric acid, and may lead to enhanced dermal penetration. The low account of skin irritation or reaction incidences among these workers is contributed to their ethnicity as well as to the low sensitisation potential of copper. Recommendations on how to lower dermal exposure and improve workers’ skin barrier function are made.
MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

No
A new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for ¿/2 resonators). Preliminary results of such a logarithmic ten-turn (2 × 5 turns) spiral, realized with double-sided YBCO thin film, showed a Q.-factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results.

Le caryotype moléculaire permet d’identifier un CNV chez 10-14% des individus atteints de déficience intellectuelle et/ou de malformations congénitales. C’est pourquoi il s’agit maintenant de l’analyse de première intention chez ces patients. Toutefois, le rendement diagnostique n’est pas aussi bien défini en contexte prénatal et l’identification de CNVs de signification clinique incertaine y est particulièrement problématique à cause du risque d’interruption de grossesse. Nous avons donc testé 49 fœtus avec malformations majeures et un caryotype conventionnel normal avec une micropuce CGH pangénomique, et obtenu un diagnostic dans 8,2% des cas. Par ailleurs, des micropuces à très haute résolution combinant le caryotype moléculaire et le génotypage de SNPs ont récemment été introduites sur le marché. En plus d’identifier les CNVs, ces plateformes détectent les LOHs, qui peuvent indiquer la présence d’une mutation homozygote ou de disomie uniparentale. Ces anomalies pouvant être associées à la déficience intellectuelle ou à des malformations, leur détection est particulièrement intéressante pour les patients dont le phénotype reste inexpliqué. Cependant, le rendement diagnostique de ces plateformes n’est pas confirmé, et l’utilité clinique réelle des LOHs n’est toujours pas établie. Nous avons donc testé 21 enfants atteints de déficience intellectuelle pour qui les méthodes standards d’analyse génétique n’avaient pas résulté en un diagnostic, et avons pu faire passer le rendement diagnostique de 14,3% à 28,6% grâce à l’information fournie par les LOHs. Cette étude démontre l’utilité clinique d’une micropuce CGH pangénomique chez des fœtus avec malformations, de même que celle d’une micropuce SNP chez des enfants avec déficience intellectuelle.
Molecular karyotyping identifies a CNV in 10-14% of individuals affected with intellectual disability and/or congenital abnormalities. Therefore, it is now the first-tier analysis for these patients. However, the diagnostic yield is not as clear in the prenatal context, and the risk of pregnancy termination makes the detection of variants of uncertain clinical significance particularly problematic. We tested 49 fetuses with major malformations and a normal karyotype, using a pangenomic CGH array, and obtained a diagnosis in 8.2% of cases. Furthermore, high-resolution microarrays combining molecular karyotyping and SNP genotyping were recently introduced on the market. In addition to identifying CNVs, these platforms detect LOHs, which can indicate the presence of a homozygous mutation or of uniparental disomy. Since these abnormalities can be associated with intellectual disability or congenital abnormalities, their detection is of particular interest for patients whose phenotype remains unexplained. However, the diagnostic yield obtained with these platforms is not confirmed, and the real clinical value of LOH detection is not yet established. We tested 21 children affected with intellectual disability for whom standard genetic analyses failed to provide a diagnosis, and were able to increase the diagnostic yield from 14.3% to 28.6% as a result of the information provided by LOHs. This study shows the clinical usefulness of pangenomic CGH arrays in fetuses with malformation(s), as well as that of SNP arrays in children with intellectual disability.