<p>  </p> <p>High cycle fatigue, regarding turbine engines, is one of the main causes of rotating component failure. Specifically, the blades of the wheels in the fan, compressor, and turbine sub-assemblies. Traditionally strain gauges are employed as a means of measuring blade vibration during component or full engine development testing. For rotating machinery, strain gauges require the use of a slip ring or a telemetry package. This becomes increasingly complicated as the number of strain gauges increase, thus the need for a more non-intrusive measurement capability for discernment of blade stress responses. Non-Intrusive Stress Measurement Systems (NSMS) allow engineers to detect high cycle fatigue (HCF) issues prior to component failure. It is important for the turbine engine industry to monitor for high cycle fatigue issues to maintain a fleet readiness. When unexpected HCF causes component or system failure the potential consequences are grounded fleets, cancelled flights, monetary loss, and loss of life. Once these issues occur an investigation is initiated and could take a few weeks to several months or more to resolve. This time impacts the engine companies as well as the people dependent upon functional engines. HCF monitoring processes and techniques are crucial to preserving fleet maintenance. One of the ways to prevent premature HCF failure is by detecting cracks in the blades or the wheels of the rotor.</p> <p>It <a href="https://hammer.purdue.edu/account/home#_msocom_1" target="_blank">[NLK1]</a> is the subject of this thesis to determine whether the static deflection of the blade as it rotates will begin to grow independent of rotational changes experienced by the rotor for an internal crack in the wheel as opposed to the blade of a rotor. Should a crack in the wheel occur, the stiffness should decrease, which would manifest when testing the rotor’s natural frequencies as a decrease in the natural frequency compared to an un-cracked rotor. The experiment was conducted using analysis tools for predicting blade natural frequencies of the pre-cracked rotor as well as physical experiments to determine the natural frequencies of the post-cracked rotor. The spin facility set up, data acquisition, data reduction, experiment details and results are provided. Both strain gauges and NSMS techniques were used to measure the natural frequencies of the rotor, and detection of damage while mounted in the spin facility. This research effort concluded it is possible to detect a crack in the wheel of a rotor using the NSMS blade stack capability. It is necessary to have a baseline vibration survey to understand the pre-damaged static deflection of each blade. This research also concluded that a comparison of the pre-cracked and post-cracked natural frequencies manifested roughly a 5% decrease. With a crack in the wheel, the expected stiffness of the wheel would decrease, thus, causing a decrease in the natural frequency of the component. This is evident in the comparison of the pre-cracked ping test data and the post-crack bench test data. In summary, it is possible to detect an internal crack of a rotor and the natural frequencies of the blades can change with an internally cracked wheel. </p>

Because blades in jet engine compressors are subject to dynamic loads based on the engine's speed, it is essential that the blades are properly "tuned" to avoid resonance at those frequencies to ensure safe operation of the engine. The tuning process can be time consuming for designers because there are many parameters controlling the geometry of the blade and, therefore, its resonance frequencies. Humans cannot easily optimize design spaces consisting of multiple variables, but optimization algorithms can effectively optimize a design space with any number of design variables. Automated blade tuning can reduce design time while increasing the fidelity and robustness of the design. Using surrogate modeling techniques and gradient-free optimization algorithms, this thesis presents a method for automating the tuning process of an airfoil. Surrogate models are generated to relate airfoil geometry to the modal frequencies of the airfoil. These surrogates enable rapid exploration of the entire design space. The optimization algorithm uses a novel objective function that accounts for the contribution of every mode's value at a specific operating speed on a Campbell diagram. When the optimization converges on a solution, the new blade parameters are output to the designer for review. This optimization guarantees a feasible solution for tuning of a blade. With 21 geometric parameters controlling the shape of the blade, the geometry for an optimally tuned blade can be determined within 20 minutes.

Moravian-Silesian Region is a part of an area so called „small black triangle". It is an area of higher pollution caused by some kind of industrial zone. This region belongs to the most polluted atmosphere in the Czech Republic. The pollution is caused by various factors but the most negative one is metallurgic industry but also mine-mining, transport, and small local furnaces. To analyze pollution, the instrumental neutron activation analysis with analyzing of moss samples were used. The moss has rudimentary root system so it takes nutrients as well as heavy metals from the atmosphere. All irradiation has performed in the Joint Institute for Nuclear Research (JINR) in the Frank Laboratory of Neutron Physics (FLNP) at the reactor IBR-2M. Two kinds of irradiation have been performed as short-term irradiation as long-term irradiation. Short-term irradiation took about 3 mins and then short-lived isotopes were measured for about 15 mins. The long-lived isotopes were measured twice after about 4 days for 30 mins and after 23 days for 90 mins after 3 days of irradiation. For long term irradiation, the cadmium-screened irradiation channel was used. For analyzation and data processing the software Genie 2000 as well as software developed at FLNP JINR were used. In sum, 43 samples of the terrestrial mosses (Hypnum cupressiforme, Pleurozium schreberi and Brachythecium rutabulum) were collected in autumn of 2015 in which the concentration of 38 elements were determined, including heavy metals. As a result, the factor analysis have been performed as well as maps analyzation.

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In first part thesis contains known methods of license plate detection. Preprocessing-based methods, AdaBoost-based methods and extremal region detection methods are described.Finally, there is a described and implemented own access using local detectors to creating visual vocabulary, which is used to plate recognition. All measurements are summarized on the end.

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Variable renewable energy sources typically connect to the power grid through power electronic interfaces. Increased use of such sources can cause issues for conventional distance protection. The purpose of distance protection is to detect transmission line faults and trip circuit breakers accordingly in order to maintain power system stability and power quality, and to ensure the safety of equipment and humans. Conventional distance protection solutions work satisfactorily in grids dominated by synchronous generators, but it has been recognized in industry and academia that new solutions may be needed in power grids dominated by power electronics interfaced generation due to the non-linear system impacts introduced by such sources. It was the aim of this thesis project to investigate the performance of alternative solutions used toward this end, specifically time domain distance protection solutions which are immune to the dynamics of power electronics interfaced sources. Short-circuit simulations for different fault scenarios have been performed in PSCAD, utilising models with a wind farm connected via a single overhead transmission line to a grid represented by a voltage source and impedance. The PSCAD line voltages and currents were processed in Matlab where both a more conventional phasor-based algorithm and a time domain differential equation based algorithm were implemented and simulated. A tripping logic based on detecting stable fault distance estimates within the primary protection zone was used. The implemented algorithms were compared for 96 scenarios in their ability to identify the faults and fault types, estimate the fault distances, and in their tripping speed. The results show an overall better performance for the differential equation algorithm compared to the conventional phasor-based algorithm, with more successful trips, faster tripping speed and superior distance estimate convergence on the correct fault distance. Some limitations have also been identified for the differential equation algorithm such as a fault impedance trajectory in the impedance plane which can lead to incorrect trips during external faults when using conventional tripping logic. It is suggested that more research be done regarding the differential equation algorithm with the next step being further algorithm development and testing when using fault impedance estimates and a tripping zone in the impedance plane. / Variabla förnybara energikällor använder vanligtvis kraftelektronik som ett gränssnitt för kopplingen till kraftnätet och ökningen av sådana källor kan skapa problem för konventionella distansskydd. Distansskydds syfte är att detektera jord- och fasfel på kraftledningar samt att skicka utlösningssignaler till strömbrytare för att isolera felet, vilket behövs för att upprätthålla kraftnätets stabilitet, effektkvalitet samt för att säkerställa säkerhet för komponenter och människor. Konventionella distansskydd fungerar bra i kraftnät dominerade av synkrongeneratorer men det har uppmärksammats av industrin samt den akademiska världen att nya lösningar kan behövas i kraftnät som är dominerade av energikällor med kraftelektronik-gränssnitt på grund av dess olinjära dynamik. Syftet med detta examensarbete är att undersöka prestandan av alternativa algoritmer för distansskydd som kan användas mot detta ändamål, specifikt tidsdomän algoritmer som är immuna mot dynamiken introducerad av kraftelektroniken. Kortslutningssimuleringar för olika scenarion har simulerats i PSCAD modeller med en vindkraftpark kopplad i änden på kraftledningen, där spänningarna och strömmarna sparas för vidare analys. Resultaten från PSCAD simuleringar bearbetades i Matlab där både en konventionell algoritm baserad på fasvektorer samt en tidsdomän algoritm baserad på differentialekvationer har implementerats och simulerats. Den implementerade utlösningslogiken baserades på att detektera stabila estimeringar för avståendet mellan skyddsreläet och felet på kraftledningen, där utlösningssignaler skickas för stabila estimeringar detekterade inom den primära skyddszonen för reläet. De implementerade algoritmerna jämfördes i 96 olika scenarion för deras förmåga att: identifiera fel och feltypen, estimera avståndet mellan skyddsreläet och felet samt för deras utlösningstider. Resultaten visar en i överlag bättre prestanda för differentialekvations-algoritmen jämfört med den konventionella fasvektor-baserade algoritmen med fler lyckade strömbrytarutlösningar, snabbare utlösningstider samt bättre konvergens och mer korrekt lokalisering för avståndsestimeringen mellan skyddsreläet och felet. Vissa limitationer har även identifierats för differentialekvations-algoritmen, exempelvis en felimpedans-kurva i impedansplanet vilket kan leda till inkorrekta utlösningar för externa fel om ett konventionellt impedansområden används för utlösningslogiken. Det föreslås att mer forskning bör utföras kring differentialekvations-algoritmen med nästa steg att vidare utveckla algoritmen samt utföra tester vid användande av felimpedansestimeringar och en utlösningslogik baserad på impedansområden.

[pt] A Manutenção e Inspeção Baseada em Risco (IBR) compreende a utilização de ferramentas de cálculo de engenharia como análise estrutural por elementos finitos, análise de corrosão e fadiga, análise de risco e confiabilidade estrutural, de forma integrada, a fim de elaborar os planos de inspeção de maneira racional otimizada. No caso de inspeção de balsas para serviço offshore, particularmente da estrutura do convés principal da balsa, técnicas de análise de risco podem ser aplicadas para que se possam determinar os intervalos de inspeção de cada elemento da estrutura. Como resultado final, tem-se um plano de inspeção otimizado e aplicado à realidade estrutural da unidade. A presente dissertação tem por objetivo propor um método de predição baseado em IBR para aperfeiçoamento de processos de tomada de decisão referentes à manutenção de balsas para serviço offshore de uma grande empresa brasileira do setor de petróleo e gás natural. Apresenta-se um estudo de caso focalizando uma aplicação do método de predição em uma das balsas de serviço offshore da empresa – a Balsa de Serviço 3 (BS-3). Os resultados do estudo de caso permitem afirmar que a adoção de ferramentas de inspeção baseada em risco podem aumentar o TLV (Tempo Limite de Vida) das balsas de serviço offshore. Como consequência, os benefícios potenciais são: redução das incertezas associadas; identificação de avarias devido à deterioração estrutural; redução de custos de manutenção; e, principalmente, diminuição do tempo da paralisação das balsas de serviço. / [en] Risk-Based Inspection (RBI) involves the use of engineering calculation tools such as finite element structural analysis, corrosion and fatigue analysis, risk analysis and structural reliability in an integrated framework, in order to develop inspection plans in a rational and optimized manner. RBI attempts to map the structure degradation curve, in deterministic or probabilistic way. Once defined the degradation curve for the different areas of the structure, risk analysis techniques are applied to determine inspection intervals concerning each element of the structure. As final result, it is possible to obtain an optimized inspection plan applied to the structural reality of the unit. The objective of this dissertation is to propose a prediction method, based on RBI, to improve the decision-making process focusing on maintenance of offshore service barges of a large oil and gas company in Brazil. It presents a case study concerning an application of this prediction method in one of the offshore service barges of this company – Offshore Service Barge 3 (BS-3). The results show that the adoption of preventive inspections can enlarge the TLV (Time Limit of Life) of this type of unit. As a consequence, the potential benefits are: reduction of uncertainties; identification of faults due to structural deterioration; maintenance costs reduction; and, decreasing of time breakdowns concerning barge services.