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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

A machine component monitoring system using audio acoustic signals

Nor, Mohd Jailani Mohd January 1996 (has links)
The main objective of this study is to develop a new type of machine-component monitoring system which is non-intrusive and non-contact in nature. Moreover, the design of the system to be developed must be robust enough for it to be implemented in an industrial environment. Therefore, this study was initiated to overcome some of the problems that were encountered using the well-established vibration method. For instance, vibration measurement of a machine component is dependent on the quality of contact between an accelerometer with a vibrating surface. Vibration measurement of a machine component is also affected by the vibration of other machine components near the vicinity, in addition to the presence of power-supply-line frequency and its harmonics. On the other hand, the application of a desirable non-intrusive and a non-contact nature of sound pressure measurement method is difficult to carry out if the background sound level is high. This is because sound pressure measurement is dependent on the characteristics of a sound field where a measurement is carried out. For these reasons, air-particle acceleration signals were utilised in the study. Air-particle acceleration is a vector quantity and measurement of vector property can improve the signal-to-noise ratio of the measured signal, even in a noisy environment. A dedicated test rig was constructed to carry out the experiments and to test the hypothesis. Rolling element bearings were used for the experiment because of the many different types of defect that can develop in them, such as inner race, rolling element and outer race defects. Moreover, the dynamic behaviour of bearings are well understood and can be compared with experimental results obtained from the study. Several different methods of analysis were used in the study including statistical, spectral, cepstral and wavelet transform methods. The results from using air-particle acceleration signals were compared with results obtained from utilising sound pressure and vibration signals. These results showed that the performance from using air-particle acceleration signals were superior to the performance from using sound pressure signals. Results from the analysis of air-particle acceleration signals can clearly indicate the presence of a defective component in the test-bearing. This is so even when the overall background noise was 14dB higher than the overall noise level emitted by the test-bearing. Moreover, the sensitivity of the measurement of air-particle acceleration signal to indicate the presence of a defective bearing was similar to the sensitivity when using conventional vibration equipment. Applications of artificial neural networks were also included for automatic identification of defect signals. The multilayer perceptron network was chosen and tested to classify the bearing signals because of the suitability of this type of network to be used for pattern recognition. Finally, a new type of machine-component monitoring system using air-particle acceleration signal was successfully developed and tested in industry.
352

Field sampling and flow injection strategies for trace analysis and element speciation

Fernandez, Maria Luz Mena January 1997 (has links)
Over the last two decades research has shown that the different forms of trace elements in the environment can cause a variety of health concerns as a result of differences in toxicity. The need to establish efficient, effective and reliable speciation methods has become paramount. A basic aim of this work has been to advance speciation measurement capability for key trace elements (mercury, lead and chromium) by devising an integrated analytical approach that links the sample collection, sample preservation and laboratory measurements in an unified manner. An introductory chapter first reviews the occurrence of organometallic compounds in the environment and focuses on the identification of the "environmental compartments" where transformations of such species can take place. Speciation studies also assist in understanding the biogeochemical cycling of trace elements. Moreover, a review of the various methodologies used for trace element speciation measurements including hyphenated techniques and/or a variety of chemical/physical pretreatments in combination with flow injection (FI) is discussed. Chapter 2 describes mercury speciation experiments utilising gas chromatography-microwave induced plasma-atomic emission spectrometry (GC-MIP-AES) and FI. The approach was based on the preconcentration of mercury on sulphydryl cotton and after elution from the microcolumn, separation and quantitation of methyl-, ethyl- and inorganic mercury species. Method development experiments were performed using a derivatisation technique which gave low contamination and allowed rapid analysis of samples. The microcolumn technique was transferred to the field and speciation of mercury in surface waters of the Manchester Ship Canal was undertaken and high methylmercury concentrations (0.052-0.182 ug 1 -1, as Hg) were detected. In so doing the new approach offered the preservation of the natural speciation state of the water sample directly at the sampling site and during the interval between collection and analysis. In chapter 3 lead studies are centred on the development of a rapid speciation scheme for neutral and cationic (organic and inorganic) lead species based on activated alumina microcolumn separation in combination with ICP-MS and FI. The approach permitted rapid assessment of the nature of lead contamination in environmental waters. Speciation of lead in surface waters of the Manchester Ship Canal was also undertaken using the field sampling approach in an attempt to confirm a transmethyllation reaction between organolead and inorganic mercury. A further application for microcolumns, in the context of speciation measurement, is their use as external calibrants and certified reference materials (CRMs) and this is discussed in the penultimate chapter. Key elements were mercury and chromium. After immobilisation of mercury species on SCF microcolumns it was found that recoveries for methyl- and inorganic mercury were quantitative over 4 months in contrast to ethylmercury which was 2 months. Similar studies for chromium species indicated ineffective elution and more vigorous conditions (microwave assisted digestion) for the elution step were used. A final chapter reviews progress and recommendations are given concerning future research and application for microcolumn field sampling in combination with instrumental analytical techniques.
353

Développement de méthodologies de tests en radiation des nanosatellites / Radiation test methods for nanosatellites

Rousselet, Mathias 16 December 2016 (has links)
L’environnement spatial est extrêmement agressif, en particulier en raison de la présence de radiations. Ces radiations produisent divers effets, soit cumulatifs soit singuliers qui mettent en péril la fiabilité des satellites. Sur les satellites à budgets contraints, l’utilisation de composant durcis est à proscrire pour des questions de coût. Les composants utilisés sont des composants commerciaux dont la tenue aux radiations n’est généralement pas connue. Sur les satellites scientifiques ou commerciaux, une procédure dite Radiation Hardness Assurance (RHA) est mise en place et vise à réduire les risque en évaluant la sensibilité aux radiations de tous les composants. Afin de garantir le niveau de fiabilité des nanosatellites, nous proposons dans le cadre de cette thèse d’aider au développement d’une RHA spécifique. / Space environment is harsh, especially because of radiations. These radiations induce cumulative and singular effects that can reduce the overall reliability of a satellite. For low-cost space systems, the use of radiation hardened components is prohibited because of their high cost. Commercial components are preferred but their radiation sensitivity is often unknown. Scientific and commercial space projects require a Radiation Hardness Assurance (RHA) process in order to reduce the risk and ensure a better reliability by providing a study at component level. We propose in this thesis the study and development of RHA methods dedicated and tailored for nanosatelittes.
354

Accelerated testing of tidal turbine main bearing in a full scale nacelle test rig

Karikari-Boateng, Kwaku Ampea January 2016 (has links)
Tidal Energy is one of the growing renewable energy technologies that is aimed at tackling global energy challenges. The Horizontal Axis Tidal Turbine (HATT) is an in-stream Tidal Energy Converter (TEC) which extracts kinetic energy from tidal flows. These tidal turbines face many reliability challenges due to their complexity, harsh operating environment and low accessibility. One of the component contributing significantly to the reliability of a TEC is the bearing supporting the rotating shaft within the nacelle. The reliability assessment of this component is essential during the design process and before their eventual deployments. This work is describes shaft bearing reliability assessment procedures. In recent years, the Offshore Renewable Energy (ORE) Catapult’s National Renewable Energy Centre has developed a dedicated multi axis test facility for full scale testing of tidal turbine nacelles and components (i.e. Nautilus). This work presents a methodology for testing tidal turbine shaft bearings in a representative manner in the full scale nacelle test rig, Nautilus. Two aspects are considered, namely the damage assessment and the damage replication in an accelerated manner. The damage assessment process considers the global loading on the shaft bearing and a Rigid Dynamics (RD) model has been applied to identify the local bearing loads. Local loads are converted to stress enabling the identification of stress-life relationship and bearing damage. The damage replication process is aimed to evaluate the 20 year damage and the Acceleration by Phase-shift (AbP) method has been developed to accelerate the cumulative damage. The AbP method enables the assessment of performance characteristics of shaft bearings in a laboratory environment, reducing failure rates, validate performance in a cost effective manner by reduced testing times. Within this work, novel processes for shaft bearing reliability assessments and demonstration are suggested and it concludes with the presentation of a recommended test plan for carrying out accelerated tests on a full scale bearing.
355

Znalosti žáků ZŠ z oblasti ekologie tvorba standardizovaného testu / Ecology knowledge of the grammar school pupils development of the standardized test

GROULÍKOVÁ, Eva January 2016 (has links)
The main purpose of this diploma thesis was to develop a standardized test on the knowledge of ecology for grammar school pupils and to test it at particular schools. The situation on ecology knowledge testing in the Czech Republic is analyzed in the first section of the thesis, followed by a theory of didactical tests structure. The responses from 231 pupils (122 version A, 109 version B) were collected, analyzed, compared and discussed.
356

Vliv handlingu na osobnostní rysy hraboše polního (\kur{Microtus arvalis})

DIKOŠOVÁ, Tereza January 2016 (has links)
The aim of this study was to investigate whether daily handling in the form of tactile stimulation can ifluence behaviour of adult common voles (Microtus arvalis). The voles were tested in three types of behavioural experiments - Acoustic startle test, Open Field test (OFT), and Elevated Plus Maze test (EPM). No significant impact of handling on personality traits was detected.
357

Mimosmluvní instituty užití autorského díla / Non-contractual legal institutions of the use of copyrighted work

Čuřík, Martin January 2018 (has links)
The aim of this thesis is to summarizingly describe non-contractual institutions of the use of copyrighted work, to define this legal branch under the system of copyright law as well as to briefly introduce the essential institutes and concepts of copyright law as such. The second chapter focuses on the explanation of the concept of copyright law and its placement in the system of law. Afterwards, a brief historical background of copyright law on the territory of the Czech Republic and the most important reasons for providing copyright protection are introduced. In the third chapter, the essential concepts of copyright law are defined, such as author's work, the characteristics of author's works, categories of author's works, exceptions to copyright and the concept of authorship. The description of when the copyright protection is created follows. Then, the definition of the content of copyright, including the scope of moral and economic rights of author of the work, is presented. Finally, the institution of public domain is explained. The fourth and main chapter of this thesis contains a digression in the field of copyright contracts, followed by the introduction to the field of the non-contractual institutions of the use of copyrighted work. Next, there is an overview of the European and...
358

EVALUATING THE RELATIONSHIP BETWEEN THE PEAK RELATIONAL TRAINING SYSTEM DIRECT ASSESSMENTS AND THE KAUFMAN TEST FOR EDUCATIONAL ACHIVEMENT III

Cepeda, Alysse 01 May 2018 (has links)
The purpose of the current study was to determine the relationship between the PEAK Relational Training System Assessments and the Kaufman Test of Educational Achievement, Third Edition long form in children with autism and other cognitive or language delays. 29 participants were administered the PEAK Relational Training System Battery of Assessments and the Kaufman Test of Educational Achievement. This study sought to extend previous literature examining the validity of PEAK Assessments as compared to previously validated assessments as well as add to the body of literature examining the relationship between academic achievement and language and cognition development. Understanding the interaction between verbal behavior skills, derived relational responding, and academic skills may enable clinicians and educators to serve their learners in a more effective, comprehensive way. The results of this study suggest there is a moderately strong, statistically significant relationship between the PEAK assessments and the Kaufman Test of Educational Achievement Academic Skills Battery Composite (r=0.6675, p<0.0001, R2=.4455) and a strong, statistically significant relationship with the Kaufman Brief Achievement Composite (r=0.7974, p<0.0001, R2=.5611).
359

Zdi / Walls

FIŠAROVÁ, Zdeňka January 2014 (has links)
The thesis with title Walls consists of two parts, theoretical and practical. The practical part focuses on making clear the life of Vladimír Boucník, drawing nearer his work and it desribes technics he thought up and occupied with. It highligts similarities of his ways of work with the certain kinds of arts, which appeared ten years later, including their main representatives. It deals with some Czech and world famous artists who were finding inspiration in the same way as Vladimír Boudník. The practical part contains the cycle of digitally remastered grafic arts. The main inspirational source was the idea of explosionalism and works from the late period of Boudník´s life. The aim of this thesis is to describe the whole course of digital grafics.
360

Fyziologické parametry ovcí plemene Suffolk v chovu v lokalitě Soběslav / Physiological parameters Suffolk breed of sheep breeding in Soběslav

TOMEČKOVÁ, Andrea January 2014 (has links)
The aim of the thesis was the evaluation of commercial properties, physiological state and selected blood parameters in sheep suffolk breed with focus on monitoring increases, blood parameters and coprological examination which prooved parasitological settlement. Monitoring was conducted in 2013 and early 2014 when 17 ewes and 16 lambs were observed. For thesis purpose two samples were made on 25.3.2013 and 14.10.2013. Several elevated values have been detected among which were glucose, urea, total protein, albumin, 1 and 2 globulin and partially cholesterol. ß globulin was below the physiological range, globulin was initially below the physiological range, but in the second sampling was above the physiological range. Decreased values were observed in case of calcium concentration in blood plasma. The parasitological findings prooved presence of coccidia Eimeria and gastrointestinal nematodes.

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