Commented Translation of Technical Text

Tato bakalářská práce se zaměřuje na překlad učebního textu z oblasti elektrotechniky. Práce má za cíl přeložit a analyzovat odborný učební text a je rozdělena na tři hlavní části. V teoretické části je uvedena zejména charakteristika odborného a učebního stylu, typy překladatelských postupů, překladatelské transformace a funkční perspektiva větná. Praktická část předkládá anglický překlad úryvku ze skript a analytická část má za cíl analyzovat problémy, které se vyskytly při překladu a zhodnotit charakteristické znaky odborného učebního stylu založené na analýze tohoto překladu.This bachelor thesis deals with the translation of a didactic text from the electrical engineering field. The work aims to translate and analyze a didactic technical text and is divided into three main parts. The theoretical part introduces namely the characteristics of technical style and didactic style, types of translation procedures, translation transformation and the functional sentence perspective. The practical part presents an English translation of an excerpt taken from a university textbook and the analytic part aims presenting the problems that occurred during the translation process and the assessment of the characteristics of technical didactic style based on this translation analysis.

AN INDUCTIVE POWER TRANSFER SYSTEM WITH A HIGH-Q RESONANT TANK FOR PORTABLE DEVICE CHARGING

Master'sMASTER OF ENGINEERIN

Self-Consistent Modelling of Non-Thermal Atmospheric Argon Plasma During Arc Discharge and Its Interaction with Metal Electrodes

Heat transfer processes associated with arc plasmas are important for many industrial applications such as electric propulsion, plasma spray and arc welding. In these applications, an electric arc is used because it offers high energy densities and a controlled environment. However, it is sometimes not realizable or not economic to get the parameters within the high temperature region of plasma precisely by means of experimental measurements. A numerical model that offers reliable description of discharging process is a good choice. Any model of arc plasmas must contain not only the conservation of mass, momentum and energy, but also electromagnetic description that follows Maxwella s equations. Since the last 30 years, intensive researches embarking on nonequilibrium plasmas have led to fruitful achievements, among them NLTE (non-Local Thermal Equilibrium) model plays an important role in numerical modelling due to its superiority over LTE (Local Thermal Equilibrium) model in accounting for the difference of two phase temperatures (heavy species and electrons) that cannot be neglected near electrodes. However, deeper researches meet obstacles when the discharging system needs to be simulated self-consistently as a whole and with as few presumed conditions as possible. On one hand, discharging under high current operation tends to overheat its electrodes leading to melting or evaporating, particles from electrode material that enter the plasma will change its composition and the heat transfer process. On the other hand, therea s still a a mysteriousa region whose physical structure is so different from the main arc plasma region that cannot be accounted by conventional transport equations or theories without any extra treatments for it. This region, sometimes called sheath layer or space-charge layer, plays an important role in bridging the thermal and electric energy of arc column to electrodes. To develop a reasonable model in this region and make it compatible with the two other regions will extend the applicability of CFD model in discharging devices. The motivation of this doctoral thesis is based on my special interest in sheath region, or in other words, my pursuit of developing a self-consistent model that is capable of solving the whole plasma-electrode system. Concerning the complexity of sheath, no secondary physical phenomena such as melting and evaporating are considered in this study. For the main arc region, the plasma composition is calculated based on species conservation equations that consider both diffusion and production/loss activities of particles. And for the sake of high temperature of plasma core, ionization up to third level is applied. In the sheath layer, the effective sheath electrical conductivity is utilized, which is based on the assumption of Childa s collisionless sheath and Lowkea s expression. The ionization degree of plasma sheath plays an important role in this self-consistent method. To validate the model proposed here, several simple benchmark simulations are made and the numerical results concerning temperature, velocity and magnetic field yield satisfactory agreements with experimental or theoretical results. With the model being validated, a D.C. non-transferred plasma torch is studied. The total voltages of both situations are compared with experimental measurements. It shows that the sheath model developed in this scope make the numerical results closer to reality and is responsible for the strong fluctuation of arc jets, which also makes cathode surface temperature fluctuate accordingly. Finally, pros and cons of some new design patterns of plasma torches are discussed, with the multi anode/single cathode type DeltaGun simulated for the comparison of performances with the original type. It reveals that such kind of configuration helps to damp the unwanted arc fluctuation with multiple arc roots. It is also numerically confirmed that when an external coil is added around anode to produce a proper magnetic field, the temperature of anode attachment can be reduced due to enhanced circumferential movement of arc roots by Lorentz force, which lowers the possibility of erosion and promotes a longer lifetime

A w-band quasi-optical mode converter and gyro-BWO experiment

High power coherent microwave sources at shorter wavelengths (mm and sub-mm) are in great demand, especially in the fields of plasma physics, remote sensing and imaging and for electron spin resonance spectroscopy. Gyro-devices are by their nature particularly suited to this type of application due to the fast-wave cyclotron resonance maser instability, which is capable of producing high power radiation at frequencies that prove challenging for other sources. A W-band gyro-device based on a cusp electron beam source with a helically corrugated interaction region is currently under development to provide a continuously tuneable source over the range between 90 GHz to 100 GHz with a CW power output of ~10 kW. The work presented herein encompasses the design, construction and measurement of a prototype output launcher for this gyro-device. A corrugated mode converting horn was designed to act as a quasi-optical mode converter that converts the fundamental operating mode within the gyro-TWA (TE11) to a hybrid mode, which is closely coupled to the fundamental free space Gaussian mode (TEM00). This free space mode allows the possibility for the inclusion of an energy recovery system that can recover a percentage of the energy from the spent electron beam and is predicted to increase overall efficiency by up to 40%. For this scheme the electron beam must be decoupled from the radiation, which can pass through the collector system and vacuum window unperturbed while the electrons are collected at the energy recovery system. This type of corrugated mode converting horn was chosen due to the advantages of a greater bandwidth and the capability to provide a source that is continuously tuneable over this bandwidth. The results of the design and integration of this corrugated mode converting horn with the gyro-device are presented. The prototype operates over a continuously tuneable bandwidth of 90 to 100 GHz with a return loss better than -35 dB and a Gaussian coupling efficiency of 97.8%. The far field radiation pattern shows a highly symmetrical structure with 99.9% of the power radiated within a cone with a half angle of less than 19° and a cross-polar level less than -40 dB.High power coherent microwave sources at shorter wavelengths (mm and sub-mm) are in great demand, especially in the fields of plasma physics, remote sensing and imaging and for electron spin resonance spectroscopy. Gyro-devices are by their nature particularly suited to this type of application due to the fast-wave cyclotron resonance maser instability, which is capable of producing high power radiation at frequencies that prove challenging for other sources. A W-band gyro-device based on a cusp electron beam source with a helically corrugated interaction region is currently under development to provide a continuously tuneable source over the range between 90 GHz to 100 GHz with a CW power output of ~10 kW. The work presented herein encompasses the design, construction and measurement of a prototype output launcher for this gyro-device. A corrugated mode converting horn was designed to act as a quasi-optical mode converter that converts the fundamental operating mode within the gyro-TWA (TE11) to a hybrid mode, which is closely coupled to the fundamental free space Gaussian mode (TEM00). This free space mode allows the possibility for the inclusion of an energy recovery system that can recover a percentage of the energy from the spent electron beam and is predicted to increase overall efficiency by up to 40%. For this scheme the electron beam must be decoupled from the radiation, which can pass through the collector system and vacuum window unperturbed while the electrons are collected at the energy recovery system. This type of corrugated mode converting horn was chosen due to the advantages of a greater bandwidth and the capability to provide a source that is continuously tuneable over this bandwidth. The results of the design and integration of this corrugated mode converting horn with the gyro-device are presented. The prototype operates over a continuously tuneable bandwidth of 90 to 100 GHz with a return loss better than -35 dB and a Gaussian coupling efficiency of 97.8%. The far field radiation pattern shows a highly symmetrical structure with 99.9% of the power radiated within a cone with a half angle of less than 19° and a cross-polar level less than -40 dB

Investigating Student Understanding of Vector Calculus in Upper-Division Electricity and Magnetism: Construction and Determination of Differential Element in Non-Cartesian Coordinate Systems

Differential length, area, and volume elements appear ubiquitously over the course of upper-division electricity and magnetism (E&M), used to sum the effects of or determine expressions for electric or magnetic fields. Given the plethora of tasks with spherical and cylindrical symmetry, non-Cartesian coordinates are commonly used, which include scaling factors as coefficients for the differential terms to account for the curvature of space. Furthermore, the application to vector fields means differential lengths and areas are vector quantities. So far, little of the education research in E&M has explored student understanding and construction of the non-Cartesian differential elements used in applications of vector calculus. This study contributes to the research base on the learning and teaching of these quantities. Following course observations of junior-level E&M, targeted investigations were conducted to categorize student understanding of the properties of these differentials as they are constructed in a coordinate system without a physics context and as they are determined within common physics tasks. In general, students did not have a strong understanding of the geometry of non-Cartesian coordinate systems. However, students who were able to construct differential area and volume elements as a product of differential lengths within a given coordinate system were more successful when applying vector calculus. The results of this study were used to develop preliminary instructional resources to aid in the teaching of this material. Lastly, this dissertation presents a theoretical model developed within the context of this study to describe students’ construction and interpretation of equations. The model joins existing theoretical frameworks: symbolic forms, used to describe students’ representational understanding of the structure of the constructed equation; and conceptual blending, which has been used to describe the ways in which students combine mathematics and physics knowledge when problem solving. In addition to providing a coherent picture for how the students in this study connect contextual information to symbolic representations, this model is broadly applicable as an analytical lens and allows for a detailed reinterpretation of similar analyses using these frameworks

Surface viscometry in a uniform magnetic field

This paper addresses an original numerical coupling between surface mechanics of a gradually oxidizing liquid metal surface, and a supporting annular MHD flow, in the general layout of the classical annular viscometer, originally developed by Mannheimer et al. [J. Colloid Interface Sci., 32:195-211, 1970]. A purely hydrodynamic interplay between a main azimuthal flow (induced by a rotating floor) and a secondary overturning flow generated by centrifugation is found to be strongly affected by both surface viscous shear and surface viscous dilatation. When centrifugation competes with electromagnetic effects, advection of the main flow by the secondary flow is proved to affect significantly the core MHD flow, leading to original MHD flow patterns. The latter phenomenology reveals to be relevant to characterise the surface viscosities of a gradually oxidising liquid metal surface

Numerical methods for electromagnetic engineering: Class Notes

Full classnotes2022/20231r quadrimestre3.

Mechanics of magneto-active polymers

Magneto-active polymers (MAPs) are polymer-based composites that respond to magnetic fields with large deformation or tunable mechanical properties. While a variety of these materials exist, most are composites of a soft polymer matrix with a filler of magnetic particles. The multi-physics interactions in MAPs give them two very attractive features. First, they respond to a magnetic field with variable mechanical properties (e.g. stiffness). Second, their shape and volume may be significantly changed in a magnetic field. Both features could be tuned by engineering the microstructure of the composites. Potential applications of MAPs include sensors, actuators, bio-medicine, and augmented reality. However, their potential has not been fully uncovered, partly due to the limited understanding in the mechanisms driving the coupled multi-physics behaviors, and the lack of a quantitative tool to predict their response under various loading and boundary conditions. This study aims to enhance the understanding of mechanics of MAPs, by developing theroies and models which can explain and predict several primary features of these materials. First, the viscoelastic behaviors of ferrogels, one class of MAPs, in response to different magnetic fields are studied. A ferrogel is composed of gel-like matrix and magnetic particles that randomly distribute in the matrix. Due to the viscoelasticity of the gel-matrix, ferrogels usually demonstrate rate-dependent behaviors. However, very few models with coupled magnetic field and viscoelasticity exist in the literature, and even fewer are capable of reliable predictions. Based on the underlying principles of non-equilibrium thermodynamics, a field theory is developed to describe the magneto-viscoelasticity in solids. The theory provides a guideline for experimental characterizations and structural designs of ferrogel-based devices. A specific material model is then selected, and the theory is implemented in a finite-element code. As numerical examples, the responses of a ferrogel in uniform and non-uniform magnetic fields are respectively analyzed. The dynamic response of a ferrogel to cyclic magnetic fields is also studied, and the prediction agrees with our experimental results. In the reversible limit, our theory recovers existing models for elastic ferrogels, and is capable of capturing some instability phenomena. Second, the mechanism of the stiffening effect in magneto-rheological elastomers (MREs), a class of anisotropic MAPs, is investigated. MREs tend to be mechanically stiffer under a magnetic field. Such a stiffening effect is usually referred to as the magneto-rheological (MR) effect and often attributed to the magnetic interaction among filler particles. But the well-acknowledged dipole-interaction model fails to explain the stiffening effect in tension/compression, which was observed in experiments. Other mechanisms, such as the effect of non-affine deformation, have also been proposed, but there is no conclusive evidence on the dominating mechanism for the MR effect. This study investigates various chain structures, and seeks to identify the ultimate origin of the stiffening effect in MREs. Two different methods are used for cross verification: a dipolar interaction model and a finite element simulation based on continuum field theories. Both the shear and axial deformation of the material are studied, with a magnetic field applied in the particle-chain direction. It is found that while the magnetic interaction between particles is indeed the major cause of the stiffening effect, the wavy chain structure is the key to the modulus increase. Besides, chain-chain interaction and non-affine deformation are shown to be insignificant. In addition, the dependence of the stiffening effect on filler concentration is calculated, and the results qualitatively agree with experimental observations. The models also predict some interesting results that could be easily verified by future experiments. Third, a simpler and easy-to-use homogenenous model is further developed to predict the magnetostriction and the MR effect of MAPs subjected to a uniform magnetic field. In general, the magnetic permeability of a MAP varies during a deformation due to the change of the microstructure. The strain dependence of permeability has been discussed for MAPs with various microstructures. It is shown that when the magnetostriction is primary caused by the difference in the permeability of an MAP and its surrounding media, the MR effect is due to the change of the permeability under a strain. Besides, it is found that both the magnetostriction and the MR effect are microstructure dependent. When the magnetostriction is more significant in isotropic MAPs, the MR effect only exists in anisotropic MAPs. In addition, it is shown that only the materials with wavy particle chains are possible to exhibit MR effect in tensile modulus

Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. When a known lightning strike occurs, the points of attachment and detachment on the aircraft surface are visually inspected and checked for damage by maintenance personnel to ensure continued safe flight operations. A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces. The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a "Smart skin" surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth & phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. In this paper, the theoretical mathematical framework is established for the use of open circuit sensors to perform damage detection and diagnosis on carbon fiber composites. Both computational and experimental analyses were conducted to validate this new method and system for aircraft composite damage detection and diagnosis. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. This paper also presents the shielding effectiveness along with the lightning direct effect test results from several different SansEC LSP and baseline protected and unprotected carbon fiber reinforced polymer (CFRP) test panels struck at 40 and 100 kiloamperes following a universal common practice test procedure to enable damage comparisons between SansEC LSP configurations and common practice copper mesh LSP approaches. The SansEC test panels were mounted in a LSP test bed during the lightning test. Electrical, mechanical and thermal parameters were measured during lightning attachment and are presented with post test nondestructive inspection comparisons. The paper provides correlational results between the SansEC sensors computed electric field distribution and the location of the lightning attachment on the sensor trace and visual observations showing the SansEC sensor's affinity for dispersing the lightning attachment