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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.
31

Realizace úzce směrového akustického měniče / Implementation narrowly directed beeper

Hladký, David January 2016 (has links)
The present final thesis discusses the transmission of a narrowly directional parametric sound beam through an amplitude-modulated ultrasonic wave, utilizing the effect of auto-demodulation in a nonlinear medium and ensuring the subsequent processing of the input signal for the parametric sound transmitter. Emphasis is placed on the mathematical tools that relate to parametric sound transmission in a nonlinear medium. The basic part of the thesis describes a parametric speaker and the associated amplitude modulation techniques, which constitute a major prerequisite for the processing of the transmitted signal. In the following section, the author then analyzes the computational intensity of these techniques, considering applicable hardware approaches. Finally, the fabrication and practical use of the proposed solution are discussed, including the measurement of typical parameters such as the spatial radiation characteristics, total harmonic distortion, and transmission channel bandwidth.
32

Vývoj tepelně izolačních materiálů na bázi odpadních textilních vláken / Development of thermal insulating materials based on waste textile fibers

Přikrylová, Pavlína January 2017 (has links)
The increasing quantity of waste represents serious environmental, social and economic problem. Wastes produced from industry and households. A large part of the economy transforms a certain amount of raw materials to waste in their production, because it is currently emphasis is placed on finding sustainable sources of raw materials. One of the suitable secondary raw materials can be discarded textiles or waste from the textile industry. These kinds of textile waste often ends up in landfills or incinerators, so it is from an ecological and environmentally advantageous to their further use. The diploma thesis deals with the study and development of thermal and acoustic insulation materials based on textile fibers. It focuses on the legislative requirements for waste management for the sorting of textile wastes and their subsequent modification before reuse. Further it contains kinds of textile fibers and bonding technologies thermal and acoustic insulation materials. Finally, an evaluation of thermal insulation, acoustic and mechanical properties of fibrous insulation materials.
33

Ultrazvukový směrový reproduktor / Ultrasonic Directional Speaker

Sedlák, Jiří January 2017 (has links)
The master´s thesis deals with theoretical research and practical application of the principle of spreading acoustic waves through nonlinear medium. The theoretical part describes five different types of amplitude modulation and their mathematic representation, which were verified by the program Matlab. Next, the impedance characteristic of ultrasound PZT transducer was measured and the design of PWM modulator and class D amplifier was described. The practical part of the master´s thesis contains the realization of the parametric loudspeaker assembled from the class D amplifier and the PWM modulator. In conclusion, the designed parametric loudspeaker was measured and the individual types of amplitude modulation were compared with respect to the total harmonic distortion of transmitted useful signal.
34

Budova občanské vybavenosti / Civic amenities building

Plášková, Věra January 2022 (has links)
The thesis deals with the design of a two-storey L-shaped smart building for amenities with a low energy consumption concept in mind. The ground floor will be used as a café and technical facilities. The second floor is designed for a small design office. The first part of the thesis is devoted to the architectural and structural design. The selected load-bearing system is a wall system made of Silka sand-lime blocks. The floor and roof are designed of prestressed reinforced concrete panels Spiroll. Stone wool is used as the main thermal insulation. The flat roof is designed green extensive. The second part of the thesis deals with the building environment technology, which will use energy from photovoltaic panels and will be supplied with heat from a local central heat source. Air exchange is provided by two HVAC units. Cooling is designed as a VRF system with refrigerant. The third part of the thesis deals with the acoustic assessment. The main topic is optimizing the reverberation time in the open space office. For the preparation of the thesis, the Archicad and Autocad software, MS Excel and Word or Deksoft were used.
35

Vliv vzduchotechnických zařízení na akustické mikroklima čistých prostorů / The impact of HVAC systems on the acoustic microclimate of clean rooms

Jelínek, Ondřej January 2016 (has links)
The work description is to create a system of measures to prevent the spread and the consequent attenuation of sound in air handling systems serving the cleanrooms. The thesis presents a solution to noise attenuation in the investigated area, and in HVAC duct, which uses a commercially available material in the form of sound insulation hoses. In the systém solution is part of the work focuses on the optimal design of terminal elements to distribute air in a clean room. Processing methods utilize theoretical and experimental approach. The experiment comprises a unique analysis of the sound insulation properties of selected products under specific conditions. The data obtained are analyzed and incorporated into the framework of this work created program module for determining the attenuation and noise propagation in an enclosed space. Math and physical dependence are programmed into their own DLL by programming language DELPHI.
36

Monitorování a analýza koroze výztužné oceli v železobetonových prvcích a konstrukcích akustickými metodami / Monitoring and Analysis of Corrosion of Reinforcing Steel in Reinforced Concrete Elements and Structures Using the Acoustic Methods

Timčaková, Kristýna January 2019 (has links)
The dissertation thesis deals with the study of non-destructive acoustic methods as instruments for monitoring and analysing corrosion of reinforcing steel in reinforced concrete elements. Four acoustic methods were selected for this task - the impact-echo method, the nonlinear acoustic spectroscopy method, the acoustic emission method, and the ultrasonic pulse velocity method. To verify the functionality of these methods, testing was carried out on three sets of reinforced concrete samples that had been exposed to the effects of sodium chloride, which corroded the embedded steel reinforcement in these samples. Suitable parameters were proposed for individual acoustic methods to monitor corrosion of the reinforcements. In addition, experiments were designed to demonstrate the ability of the selected acoustic methods to reveal the corrosion of steel reinforcement and its influence on the concrete matrix and to assess the condition of the degraded elements and structures. The analysis of the measurement results based on their comparison shows the advantages and disadvantages of the individual methods and of their practical applications. To verify the results, correlation with common methods that are currently used for the study of corrosion was carried out and included for example the electrical resistivity measurement of the reinforcement and simultaneous monitoring of the sample surface using a confocal microscope to record the development of microcracks during the degradation.
37

Určení hladin akustického výkonu tepelného zařízení stanovením akustické intenzity / Determination of sound power levels of heating equipment by measurement of the acoustic intensity

Wagnerová, Klára January 2016 (has links)
This thesis concerns method of determining sound power level of heating devices from acoustic intensity as a primary measured value. Thesis describes the characteristics of acoustic parameters and principles of acoustic measuring. Method of measurement at discret points according to ČSN EN ISO 9614-1 is compared with measurement by scanning according to ČSN ISO 9614-2. Methods are evaluated teoreticly as well as practically by companing results of experimental testing. Thesis also includes description of created model which evaluates acoustic measurement acording to the definitionof point method. The model is designed for measuring chain of Engineering Test Institute, Public Enterprise (SZU).
38

Možnosti uplatnění metody dílčího oslabení výkonu v praxi / The Possibilities Exercise of Method Partial Weakening Operation in Practise

PROKOPCOVÁ, Miloslava January 2008 (has links)
The method partial weakening operation evolves cognitive function by the children in all areas cognition: optical and acoustic sensation, cubic orientation, connecting of sensation especially optical and acoustical (intermodalita), gradual thinking from simplest to more complicated (serialita), also evolve motorial abilities, speech and communication. At the same time also evolve social relations, moral-ethic principles and administer to general evolvement children{\crq}s personality in preschool and younger school age. The graduation these is structured to chapters. The first to third chapter i. a. treats of history of method, aetiology, clinical symptoms, appearance, diagnostics and retrieval partial weakening operation. In the fourth chapter are analysed psychological characteristics preschool children. The fifth chapter reflects testing of optical disabled and auditory disabled children. The sixth chapter reflects the ethic dilemma work with children. The final chapter reflects expertly treated cases.
39

Vývoj izolačních materiálů na bázi druhotných textilních vláken nižší kvality / Development of insulation materials based on secondary textile fibers of lower quality

Mlynářová, Jana January 2021 (has links)
This diploma thesis is focused on a suitable midification of acoustic and thermal insulation materials from recycled textile fibres of lower quality due to improvement of their reaction to fire. The aim is to find an effective flame retardant and to verify suitable method of flame retardant application onto this type of insulation material.
40

Objektivizace Testu 3F - dysartrický profil pomocí akustické analýzy / Objectification of the Test 3F - dysarthric profile based on acoustic analysis

Bezůšek, Marek January 2021 (has links)
Test 3F is used to diagnose the extent of motor speech disorder – dysarthria for czech speakers. The evaluation of dysarthric speech is distorted by subjective assessment. The motivation behind this thesis is that there are not many automatic and objective analysis tools that can be used to evaluate phonation, articulation, prosody and respiration of speech disorder. The aim of this diploma thesis is to identify, implement and test acoustic features of speech that could be used to objectify and automate the evaluation. These features should be easily interpretable by the clinician. It is assumed that the evaluation could be more precise because of the detailed analysis that acoustic features provide. The performance of these features was tested on database of 151 czech speakers that consists of 51 healthy speakers and 100 patients. Statistical analysis and methods of machine learning were used to identify the correlation between features and subjective assesment. 27 of total 30 speech tasks of Test 3F were identified as suitable for automatic evaluation. Within the scope of this thesis only 10 tasks of Test 3F were tested because only a limited part of the database could be preprocessed. The result of statistical analysis is 14 features that were most useful for the test evaluation. The most significant features are: MET (respiration), relF0SD (intonation), relSEOVR (voice intensity – prosody). The lowest prediction error of the machine learning regression models was 7.14 %. The conclusion is that the evaluation of most of the tasks of Test 3F can be automated. The results of analysis of 10 tasks shows that the most significant factor in dysarthria evaluation is limited expiration, monotone voice and low variabilty of speech intensity.

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