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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.
1

Analysis of spatial distribution in tropospheric and sea surface temperature trends

Agudelo, Paula A. 14 April 2005 (has links)
Regional patterns in tropospheric and sea surface temperature (SST) trends are examined for the period 1979 ??01 using MSU, NCEP-NCAR, ECMWF ERA-40 reanalyses, NOAA OI SST, and the CARDS radiosonde data set. Trends are estimated using a nonparametric Mann-Kendall approach. Substantial regional variability in temperature trends is seen in all of these data sets, with the magnitude of the variability (including substantial regions with cooling trends) far exceeding the average warming trend. The global analyses from MSU and the NCAR/NCEP and ECMWF reanalyses are used to identify sampling problems in using the radiosonde network to infer global trends. Analysis of the trends in tropospheric temperature concurrent with trends in SST shows regions where the signs disagree for both surface cooling and warming. Interpretation of these differing trends using the reanalyses suggest that the models used for the reanalyses are simulating the necessary dynamics/thermodynamics thatcould lead to a tropospheric cooling in contrast to a surface warming (and vice versa).
2

Análise dinâmica de amortecedores não lineares assimétricos, com histerese e sujeitos a folga e avaliação do efeito temperatura / Dynamic analysis of nonlinear asymmetrical dampers with hysteresis and subject to clearance and temperature effect evaluation

Santade, Fransber [UNESP] 28 July 2017 (has links)
Submitted by Fransber Santade null (rebsnarf@yahoo.com.br) on 2017-09-22T14:48:21Z No. of bitstreams: 1 SANTADE, F - TESE FINAL.pdf: 14558958 bytes, checksum: 9a0972774c5e2f391f09848d2c7b5b88 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-09-25T18:18:49Z (GMT) No. of bitstreams: 1 santade_f_dr_bauru.pdf: 14558958 bytes, checksum: 9a0972774c5e2f391f09848d2c7b5b88 (MD5) / Made available in DSpace on 2017-09-25T18:18:49Z (GMT). No. of bitstreams: 1 santade_f_dr_bauru.pdf: 14558958 bytes, checksum: 9a0972774c5e2f391f09848d2c7b5b88 (MD5) Previous issue date: 2017-07-28 / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / O objetivo principal desta tese é a análise de amortecedores não lineares, incluindo os efeitos da folga, assimetria e histerese. A tese também apresenta um estudo sobre a influência da temperatura sobre esses efeitos. O estudo baseia-se em testes experimentais realizados em três diferentes amortecedores, incluindo um de atrito seco, um hidráulico e um do tipo magnetoreológico. Esses amortecedores foram testados em uma máquina de teste universal utilizando excitação cíclica para diferentes condições de amplitude, frequência e corrente elétrica no caso do amortecedor magnetoreológico. Três modelos paramétricos foram utilizados para representar as forças de amortecimento que foram medidas durante os ensaios experimentais, onde os parâmetros que definem esses modelos foram ajustados utilizando um algoritmo de otimização. A tese propõe uma contribuição para o campo de engenharia ao representar fenômenos não lineares típicos de amortecedores através de testes experimentais e descrevendo uma metodologia para representar as forças de amortecimento não linear e os efeitos da temperatura nestes modelos. / The main objective of this thesis is the analysis of nonlinear dampers including the effects of clearance, asymmetry and hysteresis. The thesis also presents a study on the temperature influence over these effects. The study is based on experimental tests performed on three different damping devices (dashpots), including a dry friction, a hydraulic and a magnetorheological dashpots. Theses dampers were tested on an universal testing machine using cyclic excitation for different conditions of amplitude, frequency and current in the case of the magnetorheological damper. Three parametric models have been used to represent the damping forces that were measured during the experimental testes, where the parameters defining these models were adjusted using an optimization algorithm. The thesis proposes a contribution to the engineering field by representing typical nonlinear phenomena of dampers through experimental tests and describing a methodology to represent the nonlinear damping forces and the effects of temperature on these models.
3

Teplotní analýza elektrického stroje / Thermal analysis of electric machine

Ječmínek, Tomáš January 2013 (has links)
This masters thesis is focuse for measuring devices of temperature and their usability and accuraci in the event of asynchronous engine in operation. The values from meusuring of engine are used for preparing optimalization of construction. The right proposal of construction is check in numerical program and the results are validation.
4

Komplexní pevnostní návrh kondenzátoru / Complex strength design of condenser

Denk, Jakub January 2017 (has links)
This diploma thesis focuses on strength design of steam condenser. The goal of the thesis is to make strength calculations for the specific operation conditions, introduce possible solutions, provide recommendations and refer to weak points of such calculation procedures. First, thermal-hydraulic design in HTRI software is performed. Strength calculations respect ČSN EN 13445 standard. Strength calculation with imported temperature field is performed in ANSYS Workbench software. In the next step, another strength calculation is realized in Sant´ Ambrogio software. Results are evaluated in conclusion chapter, including recommendations for the possible following work.
5

Syntéza elektronicky rekonfigurovatelných kmitočtových filtrů / Synthesis of the electronically reconfigurable frequency filters

Michalička, Filip January 2020 (has links)
This diploma thesis deals with design of reconection-less electronically reconfigurable filter structures which have single input and single output using unconventional active elements, which have ability to adjust one of their parameter e.g. gain or transconductance. The first part describes basic parameters of frequency filters, the division of filters by frequency transfer response and used circuit elements, their operational modes, the principle of reconnection-less electronically reconfiguration and the circuit design method MUNV. Second part describes all active elements used in the proposal of filters, their properties and the implementation using existing transistor-level models. The third part contains the design of three reconnection-less electronically reconfigurable filters and the simulations results obtained from simulation programs OrCAD Capture and PSpice. The obtained results were compared with theoretical behaviour. This part also contains results of these analyses: sensitivity, parasitic, Monte Carlo and temperature to determine the behaviour in varied cases.

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