This thesis deals with a design of an electrical drive for a sliding side door. Goal of the thesis is to design of a frequency converter for an asynchronous motor with a gearbox. In the first part, the power supply for the freqency converter is solved in form of a single phase rectifier. Power section is solved by an integrated module IKC10H60GA manofactured by Infineon. The control board is provided with circuits for communication between the processor and the power section. Auxiliary power supply is designed as a fly - back converter. The drive of the converter is realized by STM32 Nucleo - 64 board. The design of the converter and drive algorithm are described in detail.

This discourse deals with a theoretical study of the radiation passage through a diffraction screen with non-zero size in the propagation direction of the radiation, i.e. the radiation passage through a three-dimensional object. Without any loss of generality, we solve the problem for cylindrical cavity in metal. The task exceeds evidently standard scalar theory of diffraction, thus we solve the problem using a waveguiding theory. Following the principles of the electromagnetic theory, we derive required formulae to determine mode distribution at the entry of the cavity. Further, we solve numerically the radiation propagation through the cavity, then we actually seek for radiation distribution at the very end of the cavity. This yields, with a help of the discrete Fourier transform, an intensity distribution of Fraunhofer diffraction pattern, consequently compared with an intesity distribution of the radiation pattern of Fraunhofer diffraction on infinitely thin circular opening having the radius of the cylinder cavity under study. A comparison of such patterns results to a conclusion, that the cavity length has a significatn influence on the diffraction pattern and more importantly, that the scalar diffraction theory appears incorrect for a coherent light passage through cavities longer than their radius squared. Similarly, the same conclusion is inversely proportional to a wavelength of the interacting radiation. Finally, we mention an existence of the so called "focal regime", when the radiation repeatedly exhibits roughly one order increased intensity on the symmetry axis of the cavity.

The main goal of my work is the electrically commutated motor with the vector control’s application in the environment of Matlab – Simulink. The theoretical preamble of this document is dedicated to the physical construction of the EC motors. The most common methods are described in the following text – namely it is scalar control, direct torque control and vector control. The conclusion of this work includes the description and analyse of the single parts of a created model of concrete EC motor with the vector control, and simulations results’ evaluation.

Orientador: José Fernando de Jesus / Resumo: Estudamos o campo escalar real como um possível candidato para explicar a matéria escura no universo. No contexto de um campo escalar livre com potencial quadrático, após encontrar as equações dinâmicas do modelo usamos os dados observacionais para limitar os parâmetros livres e assim encontrar um limite inferior para o valor da massa que foi da ordem de $10^{-34}$eV, esse valor está próximo ao encontrado por alguns autores. Não foi possível encontrar um limite superior para a massa da matéria escura do campo escalar combinando os dados de $H(z)$, SN Ia. Como verificado neste trabalho e observado em outros estudos, a matéria escura pode ser descrita por um campo escalar real. Em outra linha de pesquisa, usando um método estatístico não-paramétrico envolvendo os chamados Processos Gaussianos, obtivemos um valor do redshift de transição, $z_t$, de $z_t = 0.59^{+0.12}_{-0.11}$ para dados de $H(z)$ e $z_t= 0.683^{+0.11}_{-0.082}$ para dados de SNs Ia. / Abstract: We studied the real scalar field as a possible candidate to explain the dark matter in the universe. In the context of a free scalar field with quadratic potential, after finding the dynamic equations of the model we used the observational data to limit the free parameters and thus find a lower limit for the mass value that was in the order of 10−34 eV , this value is close to that found by some authors. It was not possible to find an upper limit for the mass of dark matter in the scalar field by combining the H(z) + SNe Ia data. As verified in this work and observed in other studies, dark matter can be described by a real scalar field. In another line of research, using a non-parametric statistical method involving the so-called Gaussian Processes, we obtained a value of the transition redshift, zt , of zt = 0.59+0.12 −0.11 for H(z) data and zt = 0.683+0.11 −0.082 for SNs Ia data. / Mestre

No description available.

Turbulent mixing is present in many pulp and paper processes. It is a particularly important factor in the design and improvements of the paper machine headbox, influencing the final paper structure. During this project, experimental methods to quantify the effect of fibers on turbulent suspension flows have been developed, and then used for studying turbulent mixing in fiber suspensions. A technique that uses microprobes to measure passive scalar mixing of salt for the characterization of turbulent fluctuations in a fiber suspension flow has been developed: Conductivity micro-probes have been built and turbulence measurements have been performed in simple jet and wake flows, studying turbulent mixing between the two streams of pulp suspension, of which one has been doped with salt. A relatively new technique to measure fluid velocity non-intrusively in opaque fluids has also been tested. The technique makes use of ultrasonic pulses to obtain velocity information through the Doppler-shift of reflected pulses. The main efforts reported on in the thesis are focused on method design and development as well as method evaluation.

Abstract in English / The research will analyze and compare the current research on the spectral factorization of non-singular and singular matrices. We show that a nonsingular non-scalar matrix A can be written as a product A = BC where the eigenvalues of B and C are arbitrarily prescribed subject to the condition that the product of the eigenvalues of B and C must be equal to the determinant of A. Further, B and C can be simultaneously triangularised as a lower and upper triangular matrix respectively. Singular matrices will be factorized in terms of nilpotent matrices and otherwise over an arbitrary or complex field in order to present an integrated and detailed report on the current state of research in this area. Applications related to unipotent, positive-definite, commutator, involutory and Hermitian factorization are studied for non-singular matrices, while applications related to positive-semidefinite matrices are investigated for singular matrices. We will consider the theorems found in Sourour [24] and Laffey [17] to show that a non-singular non-scalar matrix can be factorized spectrally. The same two articles will be used to show applications to unipotent, positive-definite and commutator factorization. Applications related to Hermitian factorization will be considered in [26]. Laffey [18] shows that a non-singular matrix A with det A = ±1 is a product of four involutions with certain conditions on the arbitrary field. To aid with this conclusion a thorough study is made of Hoffman [13], who shows that an invertible linear transformation T of a finite dimensional vector space over a field is a product of two involutions if and only if T is similar to T−1. Sourour shows in [24] that if A is an n × n matrix over an arbitrary field containing at least n + 2 elements and if det A = ±1, then A is the product of at most four involutions. We will review the work of Wu [29] and show that a singular matrix A of order n ≥ 2 over the complex field can be expressed as a product of two nilpotent matrices, where the rank of each of the factors is the same as A, except when A is a 2 × 2 nilpotent matrix of rank one. Nilpotent factorization of singular matrices over an arbitrary field will also be investigated. Laffey [17] shows that the result of Wu, which he established over the complex field, is also valid over an arbitrary field by making use of a special matrix factorization involving similarity to an LU factorization. His proof is based on an application of Fitting's Lemma to express, up to similarity, a singular matrix as a direct sum of a non-singular and nilpotent matrix, and then to write the non-singular component as a product of a lower and upper triangular matrix using a matrix factorization theorem of Sourour [24]. The main theorem by Sourour and Tang [26] will be investigated to highlight the necessary and sufficient conditions for a singular matrix to be written as a product of two matrices with prescribed eigenvalues. This result is used to prove applications related to positive-semidefinite matrices for singular matrices. / National Research Foundation of South Africa / Mathematical Sciences / M Sc. (Mathematics)

Black holes are one of the most interesting objects in the universe, and studying these objects should give exciting results. This research will investigate the General Theory of Relativity, explaining the essence of the theory needed for deriving solutions for a Schwarzschild black hole. This knowledge leads to deriving the equations of motion of a bosonic scalar field around a Schwarzschild black hole. Computing the dynamical evolution of that scalar field, and taking the limit far away from the black hole, gives an approximation derivation of the  Schrödinger equation. This study opens many doors to future research about black holes and scalar fields. / Svarta hål är ett av de mest intressanta objekten i universum, och därför, att studera dessa föremål bör ge spännande resultat.I detta arbete kommer den allmänna relativitetsteorin  att studeras och förklaras med allt som behövs för att härledalösningar för en Schwarzschild svart hål. Denna kunskap leder till att härleda rörelseekvationerna för ett bosoniskt skalärfält runt ett Schwarzschild svart hål.Genom att beräkna den dynamiska utvecklingen av det skalära fältet och ta gränsen långt bort från svarta hålet,så kommer det at ge en approximativ härledning av Schrödinger ekvationen. Den här typen av studier öppnar många dörrar för framtida forskning om svarta hål och skalära fält.

A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach will provide not only real-time image processing at the speed of light but also a preview option allowing the user or the artist to preview the effect on various parts of the object in order to optimize the outcome. The work presented in this dissertation was inspired by the idea of optically created special effects, such as painterly effects, encoded in images captured by photographic or motion picture cameras. As part of the presented work, compact relay optics was assessed, developed, and a working prototype was built. It was concluded that even though compact relay optics can be achieved, further push for compactness and cost-effectiveness was impossible in the paradigm of bulk macro-optics systems. Thus, a paradigm for imaging with multi-aperture micro-optics was proposed and demonstrated for the first time, which constitutes one of the key contributions of this work. This new paradigm was further extended to the most general case of magnifying multi-aperture micro-optical systems. Such paradigm allows an extreme reduction in size of the imaging optics by a factor of about 10 and a reduction in weight by a factor of about 500. Furthermore, an experimental quantification of the feasibility of optically created special effects was completed, and consequently raytracing software was developed, which was later commercialized by SmARTLens(TM). While the art forms created via raytracing were powerful, they did not predict all effects acquired experimentally. Thus, finally, as key contribution of this work, the principles of scalar diffraction theory were applied to optical imaging of extended objects under quasi-monochromatic incoherent illumination in order to provide a path to more accurately model the proposed optical imaging process for special effects obtained in the hardware. The existing theoretical framework was generalized to non-paraxial in- and out-of-focus imaging and results were obtained to verify the generalized framework. In the generalized non-paraxial framework, even the most complex linear systems, without any assumptions for shift invariance, can be modeled and analyzed.

No description available.