Tesis sobre el tema "Double-ring"
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Chu, Tiensuu. "Double linked backbone ring interconnected network". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43081.
Texto completoMaster of Science
Roh, Chung-Hee. "Electron transport through double quantum dots in an Aharonov-Bohm ring". Muncie, Ind. : Ball State University, 2008. http://cardinalscholar.bsu.edu/382.
Texto completoGrissino-Mayer, Henri D., Georgina G. DeWeese y Dustin A. Williams. "Tree-Ring Dating of the Karr-Koussevitzky Double Bass: A Case Study in Dendromusicology". Tree-Ring Society, 2005. http://hdl.handle.net/10150/262640.
Texto completoPerkins, Abigail C. "Electron spin-polarization via Zeeman and Aharonov-Bohm effects in a double quantum dot ring". CardinalScholar 1.0, 2009. http://liblink.bsu.edu/uhtbin/catkey/1540705.
Texto completoIntroduction -- AB-oscillations and resonances in a double quantum dot ring -- Results for combined Zeeman and AB effects -- Spin-polarization.
Department of Physics and Astronomy
Johnejack, Kent Robert 1958. "Measurement of saturated hydraulic conductivity with a sealed double ring infiltrometer at Page Ranch, Arizona". Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278186.
Texto completoBagwell, Ross David. "Bifurcation and Stability of a Ring Problem Motivated by the Mechanics of Double-Walled Carbon Nanotubes". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1335288394.
Texto completoNordeman, Erinn Mary y Erinn Mary Nordeman. "The Endless Chain". Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625683.
Texto completoPettyjohn, William Randall. "Infiltration rate and hydraulic conductivity of sand-silt soils in the Piedmont physiographic region". Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53023.
Texto completoAlmeida, de Godoy Vanessa. "Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies". Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/102405.
Texto completoNumerical models are becoming fundamental tools to predict a range of complex problems faced by geotechnical and geo-environmental engineers. However, to render the model reliable for future predictions, the model input parameters must be determined with consideration of the scale effects. In this context, this thesis focuses on upscaling of water flow and mass transport in a tropical soil by means of numerical, laboratory and field studies. This thesis is organized in four parts. First, the heterogeneity, correlation and cross-correlation between solute transport parameters (dispersivity, ¿, and partition coefficient, Kd) and soil properties were studied in detail. In this part, it was verified that the hydraulic conductivity (K) and solute transport parameters are highly heterogeneous, while soil properties not. Spatial correlation of ¿, K, and statistically significant variables were studied, and it would probably improve the estimation only in a small-scale study, since the spatial correlation were only observed up to 2.5 m. This study was a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the one that should be included in future studies. In the second part, scale effect on K, dispersivity and partition coefficient of potassium and chloride is studied experimentally by means of laboratory and field experiments. The purpose of was to contribute to the discussion about scale effects on K, ¿ and Kd and understanding how these parameters behave with the change in the scale of measurement. Results shows that K increases with scale, regardless of the method of measurement. Dispersivity trends to increases exponentially with the sample height. Partition coefficient, tend to increase with sample length, diameter and volume. These differences in the parameters according to the scale of measurement must be considered when these observations are later used as input to numerical models, otherwise the responses can be misrepresented. Third, stochastic analysis of three-dimensional hydraulic conductivity upscaling was performed using a simple average and the Laplacian-with-skin methods for a variety of block sizes using real K measurements. In this part it was demonstrated the errors that can be introduced by using a deterministic upscaling using simple averages of the measured K without accounting for the spatial correlation. The application shows that K heterogeneity can be incorporated in the daily practice of the geotechnical modeler. The aspects to consider when performing the upscaling were also discussed. Finally, the dependence of the exponent of the p-norm as a function of the block size was analyzed. In the last part, an application of stochastic upscaling of hydrodynamic dispersion coefficient (D) and retardation factor (R) was performed using real data aiming to reduce the lack in experimental upscaling of reactive solute transport research. Upscaling of D was done using macrodispersion method. Simple average method based on p-norm was used to perform R upscaling. A good propagation of the uncertainties was achieved. Simple upscaling methods can be incorporated to the modeling practice using commercial transport codes and properly reproduce de transport at coarse scale but may require corrections to reduce smoothing of the heterogeneity caused by the upscaling procedure.
Els models numèrics s'estan constituint en eines fonamentals per a realitzar prediccions d'una àmplia gamma de problemes enfrontats per enginyers geotècnics i geoambientales. No obstant açò, perquè aquests models puguen realitzar prediccions fiables, els paràmetres d'entrada del model han de considerar l'efecte escala. En aquest context, aquesta tesi es concentra en les regles del canvi d'escala dels paràmetres de flux i transport de massa en un sòl tropical a través d'estudis numèrics, de laboratori i de camp. Aquesta tesi està organitzada en quatre parts. Primer, l'heterogeneïtat, correlació i correlació creuada entre els paràmetres de transport de soluts (dispersivitat, ¿, i coeficient de partició, Kd) i les propietats del sòl van ser estudiades detalladament. En aquesta part va ser verificat que la conductivitat hidràulica (K) i els paràmetres de transport de soluts són altament heterogenis, mentre que les propietats del sòl no ho són. La correlació espacial de ¿ i K amb variables estadísticament significatives va ser estudiada. Aquest resultat probablement podrà millorar l'estimació en casos d'estudis de xicoteta escala a causa que solament va ser observada correlacions de fins a 2,5 m. Aquest estudi va ser un primer intent d'avaluar la variació espacial en el coeficient de correlació dels paràmetres de transport d'un solut reactiu i d'un no reactiu, indicant les variables més rellevants i aquelles que haurien de ser inclosas en estudis futurs. En la segona part, l'efecte escala en K, dispersivitat i coeficient de partició de potassi i clorito va ser estudiat experimentalment a través d'experiments de laboratori i de camp. L'objectiu d'aquesta part va ser contribuir a la discussió sobre l'efecte escala en K, ¿ i Kd, i entendre com aquests paràmetres es comporten amb el canvi d'escala de mesurament. La dispersivitat tendeix a augmentar amb l'altura de la mostra, és a dir, amb la longitud del transport, de manera exponencial. El coeficient de partició tendeix a augmentar amb l'altura, el diàmetre i el volum de la mostra. Aquestes diferències en els paràmetres d'acord amb l'escala de mesurament han de ser considerats quan aquests valors siguen usats posteriorment com a dades d'entrada de models numèrics; d'una altra manera, les respostes poden ser malament interpretades. Tercer, anàlisis estocàstiques tridimensionals de canvi d'escala de la conductivitat hidràulica van ser realitzats usant els mètodes de mitjanes simples i de Laplace amb pell per a una varietat de grandàries de blocs usant mesuraments reals de K. En aquesta part són demostrats els errors que poden ser introduïts en usar mètodes determinístics de canvi d'escala usant mitjanes simples dels mesuraments de K sense tindre en consideració la correlació espacial. L'aplicació mostra que l'heterogeneïtat de K pot ser incorporada en la pràctica diària del modelador geotècnic. Els aspectes a considerar durant un procés de canvi d'escala també són discutits. Finalment, la dependència de l'exponent de la norma-p com a funció de la grandària del bloc va ser analitzada. En l'última part, una aplicació de canvi d'escala estocàstic del coeficient de dispersió hidrodinámica D i del factor de retard R va ser realitzada usant dades reals amb l'objectiu de reduir la falta de casos de recerca experimental de canvi d'escala de paràmetres de transport de soluts reactius. El canvi d'escala de D va ser realitzat usant el mètode de macrodispersió. El mètode de mitjana simple de norma-p va ser usat per a realitzar el canvi d'escala de R. Una bona propagació d'incerteses va ser aconseguida. Mètodes simples de canvi d'escala poden ser introduïts en la pràctica de la modelació usant programes comercials de transport i aconseguir reproduir el transport en escala gruixuda, però pot requerir correccions amb l'objectiu de reduir l'efecte de suavitzat de l'heterogeneïtat causat pel procés de canvi d'escala.
Almeida De Godoy, V. (2018). Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/102405
TESIS
Fiera, Luiz Ricardo. "Determinação do coeficiente de atrito através do ensaio do anel comparado com a extrusão por duplo copo". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/148029.
Texto completoThis work aims to study the friction coefficients obtained by the ring test, which is one of the classic methods for verification and characterization of friction, compared with DCE (Double Cup Extrusion). The tests were made using as material for preparation of specimens, the aluminum AA6351 and varying three situations lubrication, Teflon, graphite and tests without lubrication. For DCE was developed the design and manufacture of tooling, allowing vary punctures in two differ dimensions. The results obtained in the experiments with each of the techniques have been compared and shown by drawing a parallel scanned the friction and the material behavior in relation to the tools used in the experiments and lubrication changes.
Jorgenson, Matthew Allan. "A tale of two RLPAs : studies of cell division in Escherichia coli and Pseudomonas aeruginosa". Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1342.
Texto completoHaigh, Tania J. "Bose-Einstein condensates in coupled co-planar double-ring traps : a thesis presented in partial fulfillment of the requirements for the degree of Masterate of Science in Physics at Massey University, Palmerston North, New Zealand". Massey University, 2008. http://hdl.handle.net/10179/975.
Texto completoGodoy, Vanessa Almeida de. "Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-13072018-092153/.
Texto completoModelos numéricos estão se tornando ferramentas fundamentais para prever uma série de problemas complexos enfrentados por engenheiros geotécnicos e geoambientais. No entanto, para que o modelo seja confiável para previsões futuras, seus parâmetros de entrada devem ser determinados com a consideração do efeito da escala. Se há uma diferença de escalas entre a escala da observação e a escala do modelo, existem duas maneiras possíveis de considerá-la: ou constrói-se modelos com elementos de tamanhos semelhantes àqueles em que os dados foram medidos, ou definem-se algumas regras de mudança de escala. Neste contexto, esta tese enfoca a mudança de escala do fluxo de água e do transporte de massa em um solo tropical, por meio de estudos numéricos, laboratoriais e de campo. Esta tese é organizada em quatro partes. Em primeiro lugar, estudou-se em detalhe a heterogeneidade, a correlação e a correlação cruzada entre os parâmetros de transporte de soluto (dispersividade, α, e coeficiente de partição, Kd) e as propriedades do solo. Nesta parte, verificou-se que a condutividade hidráulica (K) e os parâmetros de transporte de soluto são altamente heterogêneos, enquanto as propriedades do solo não o são. A correlação espacial de α, K e das variáveis estatisticamente significativas foi estudada, e, provavelmente, melhoraria a estimativa apenas em um estudo em pequena escala, uma vez que a correlação espacial só foi observada até 2,5 m. Este estudo foi uma primeira tentativa de avaliar a variação espacial no coeficiente de correlação dos parâmetros de transporte de um soluto reativo e não-reativo, indicando as variáveis mais relevantes e as que devem ser incluídas em estudos futuros. Na segunda parte, o efeito de escala em K, na dispersividade e no coeficiente de partição de potássio e cloreto é estudado experimentalmente por meio de ensaios laboratoriais e de campo. O objetivo foi contribuir com a discussão sobre os efeitos de escala em K, α e Kd e entender como esses parâmetros se comportam com a mudança na escala da medição. Os resultados mostram que K aumenta com a escala, independentemente do método de medição. A dispersão tende a aumentar de maneira exponencial com a altura da amostra. O coeficiente de partição tende a aumentar tanto com o comprimento, quanto com o diâmetro e o volume da amostra. Essas diferenças nos parâmetros de acordo com a escala de medida devem ser consideradas quando essas observações são posteriormente usadas como entrada para modelos numéricos, caso contrário, as respostas podem ser mal representadas. Em terceiro lugar, uma análise estocástica tridimensional da mudança de escala da condutividade hidráulica foi realizada usando tanto média simples quanto o método Laplaciano-com-pele para vários tamanhos de blocos usando medidas K reais. Nesta parte, foram demonstrados os erros que podem ser introduzidos ao se usar métodos determinísticos de mudança de escala, usando médias simples das medições de K sem se considerar a correlação espacial. A aplicação das técnicas de mudança de escala mostra que a heterogeneidade de K pode ser incorporada na prática diária do modelador geotécnico. Os aspectos a serem considerados ao realizar a mudança de escala também foram discutidos. Finalmente, analisou-se a dependência do expoente da norma p em função do tamanho do bloco. Na última parte, uma aplicação de mudança de escala estocástica do coeficiente de dispersão hidrodinâmica (D) e do fator de retardo (R) foi realizada usando dados reais visando reduzir a falta pesquisas no tema de mudança de escala do transporte de soluto reativo. A mudança de escala do D foi feito usando o método de macrodispersão. O método da média simples baseado na norma p foi usado para executar a mudança de escala de R. A incerteza foi propagada satisfatoriamente. Métodos simples de mudança de escala podem ser incorporados à prática de modelagem usando programas comerciais, e reproduzir corretamente o transporte em escala grossa, mas podem exigir correções para reduzir o efeito suavizado da heterogeneidade causada pelo procedimento de mudança de escala.
Baxter, Iain A. "Finite Element Modeling of the Mitral Valve and Mitral Valve Repair". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22876.
Texto completoAyad, Houssam. "Antenna Performance Control using Metamaterials". Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT013/document.
Texto completoThe work in this thesis deals with metamaterials, its components and applications. A historical overview about these materials, features and researches in the domain are presented. Chiral media, binaisotropic materials and photonic crystals are also studied in order to visualize physics behind metamaterials.Electromagnetic properties in complex media are widely investigated. Starting from Maxwell’s equations, bi-anisotropic materials and their effect are deeply analyzed whereas two types of Split Ring Resonator (SRR) are treated to determine constitutive parameters of Left Handed Materials (LHM). The metamaterials are also studied as photonic crystals since the effective medium approach is not applicable when the dimensions of the inclusions tend to the operating wavelength.Moreover, SRRs and Multi SRRs are synthesized analytically and electromagnetically in order to extract their resonant frequencies. Consequently, these components could be introduced in any design; Artificial Magnetic Conductor (AMC) surface is an efficient case. Thus, a low profile antenna positioned over such surface is examined as an application of metamaterials. The results of directivity, gain and reflection coefficient are of great importance and affirm the employing of metamaterials in such applications. A dual band PCB antenna, as another application of metamaterials, is designed and simulated. The SRR element studied in the previous chapters is used as the trap which inserted in the arm of the antenna in order to create another resonance, and consequently another band is created
Salač, Jan. "Stanovení hydraulických charakteristik půdy ve vybraném zájmovém území". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372323.
Texto completoLarišová, Lucie. "Analýza vzájemného vztahu dvou metod terénního měření infiltrace vody do půdy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225525.
Texto completoKomárková, Markéta. "Vliv základní agrotechniky na fyzikální a hydrofyzikální vlastnosti půdy". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372322.
Texto completoCavalcanti, Fabio. "Desenvolvimento de um laser pulsado com emissão em 1053 nm para utilização na técnica de \"Cavity Ring-Down Spectroscopy\"". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-14102014-145230/.
Texto completoIn this work, a pulsed and Q-switched laser resonator was developed using the double-beam mode-controlling technique. A Nd:LiYF4 crystal with 0,8mol% of doping concentration was used to generate a giant pulse with duration of 5,5 ns (FWHM), 1,2 mJ of energy and 220 kW peak power for the Cavity Ring-Down Spectroscopy (CRDS) technique. The CRDS technique is used to measure absorption spectra for gases, liquids and solids. With the CRDS technique it is possible to measure losses with high degree of accuracy, underscoring the sensitivity that is confirmed by the use of mirrors with high reflectivity. With this technique, the losses by reflection and scattering of transparent materials were evaluated. By calibrating the resonant cavity, it was possible to measure the losses in the samples with resolution of 0,045%, the maximum being reached by 1,73%. The calibration was possible because there was obtained to measure a decay time of approximately 20 μs with the empty cavity. Besides was obtained a method for determining the refractive index of transparent materials with accuracy of five decimals.
Dlubala, Alain. "Etude de la reactivite de dianions formes par double deprotonation de dithioesters beta-thiosubstitues". Caen, 1987. http://www.theses.fr/1987CAEN2010.
Texto completochaw, cheng-chung y 趙正中. "An Active Double Ring Microstrip Antenna". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/38758734584284119236.
Texto completo中正理工學院
電機工程研究所
86
Recently,the communication equipments are widely used in the development of global communication. In application, these equipments adopt the microwave band for operation. Thus, the microwave circuits play a important role in modern microwave communication. Mainly, a small-size,low-cost higher-frequency and low-loss microwave circuit are necessary in practice. Generally, simplified the microwave circuit are available for small-size and low-cost. In this thesis, we proposed a method to have an alternative microstrip antenna designated active microstrip antenna. It can represent the LNA, OSC and Mixer of the conventional superheterdyn receiver in all. It is found the present method can be applied in radar and microwave systems.
Lin, Chun-Yuan y 林俊沅. "Fault Tolerant Token Ring Embedding in Double Loop Networks". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/51609292701187756500.
Texto completo國立交通大學
資訊科學學系
86
A double loop network G(n;s1,s2) is a digraph with n nodes{0, 1,..., n-1} and 2n links of the form i->i+s1 (mod n)andi ->i+s2 (mod n). A double loop network G(n;s1,s2) is LFTif there is a hamiltonian cycle in every G(n;s1,s2) - e wheree is any link in the network. Similarly, a double loop network G(n;s1,s2) is NFT if there is a hamiltonian cycle in everyG(n;s1,s2) - v where v is a node in the network. In this paper,we present necessary and sufficient conditions for LFT and NFTdouble loop networks, respectively.
Fang, Shin-Wei y 方薪惟. "The Fabrication and Characterization of Semiconductor Ring Laser With Double Ring Cavities and Y-Junction Couplers". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/97858542450922120769.
Texto completo國立高雄大學
電機工程學系碩士班
101
In this thesis a ridge waveguide ring laser with double ring cavities and Y-junction couplers had been fabricated on a MOCVD grown AlGaInP/InGaP multiple quantum well substrate. It is found that a single mode output spectrum which related to the 8 figure shape cavity formed by two circular ring cavities is dominated at threshold current density at 1.4 kA/cm2.As the injection current increased up higher until the threshold of the lasing from the solitons cavity was reached, a multi-modes output spectrum due to Fabery-Perot resonance was observed. Model based on the principle of emission rate equilibrium of the laser cavity with two ring cavities and the combination of a soliton cavity has been developed to explain the results of the output characteristics of laser devices fabricated. In addition, lasing modes from each circular ring emission was difficult to existed due to higher threshold current than the figure 8 cavity which overlapping these two ring cavities and had longer cavity length path.
Xu, Nai-Bin y 許乃斌. "A reliable and parallel double-ring FDDI metroplitan area network". Thesis, 1991. http://ndltd.ncl.edu.tw/handle/72687924021421995091.
Texto completoKuo, Chia-Ming y 郭佳銘. "Framework of Three-Dimensional Double-Ring Mobile-to-Mobile Fading Channels". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/21921770845050974085.
Texto completo中原大學
電機工程研究所
95
The fading channels have been investigated for about four decades. The related topics include space-time correlation function for the multiple-input-multiple-output (MIMO) communication systems, simulation schemes of fading channels, and estimation of Doppler shift etc.. Most researches always focus on the scattering environment of two-dimensional (2-D) base station to mobile station (BS-MS). However, the BS-MS model seems to lack of certain condition toward a realistic situation, the simultaneous mobility for both the transmitter and the receiver. Consequently, the 2-D mobile-to-mobile (M-M) communication system was proposed. This system can be applied into the ad hoc networking and dedicated short range communications systems. But in the urban, we need to consider the horizontal wave plane and vertical wave plane of received signals. In practice, one important parameter, elevation angle (EA), will be added into 2-D channel models to achieve the 3-D propagation environment. Then, it can describe the urban environment sufficiently. Therefore, in this thesis, we present a space-time-frequency correlation function (STF-CF) and a simulation scheme of 3-D double-ring mobile-to-mobile (M-M) Rayleigh fading channel. We have been discussed the STF-CF via the composition of antenna patterns, Doppler shift, and delay profile. The simulation scheme utilizes the Monte Carlo Principle and the method of the Doppler spread. Four types of the EA PDF, Aulin, Parsons, Qu-Yeap, and uniform model with different antenna array patterns, and Doppler shift will be discussed in the STF-CF and simulator. The related statistics of the simulator will be presented.
Liu, Shu-Xuan y 劉叔軒. "The Double Mach-Zehnder Interferometric Hydrophone Based on a Dual Sagnac Ring Configuration". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/92362499440606086645.
Texto completo國立中山大學
電機工程學系研究所
92
This paper reports a reciprocal Mach-Zehnder interferometer in a dual Sagnac ring configuration, and one of two arms in Mach-Zehnder interferometer is used for underwater optic fiber hydrophone. Two Mach-Zehnder interferometers operated in opposite sense are simultaneously induced from the underwater acoustic wave and the PZT phase modulation. Thus, at the output, four interferometric beams occur such that the intensity of interferometric beams will enhance. In general, one stage of a double Mach-Zehnder interferometer is just used as a sensor, another one for compensation. Specially, this paper presents two stages of a double Mach-Zehnder interferometer sense the measurand at the same time due to the topology structure of Sagnac ring pairs. In the other words, the characteristic is to win the affection of two beauties at the same time. Two rings in the same direction make a Mach-Zehnder interferometer. Besides, the inner ring in the clockwise direction and the outer one in the counterclockwise direction also make a Mach-Zehnder interferometer. So as to the unbalanced arms of the Mach-Zehnder interferometer, the underwater acoustic wave induces the light beam phase difference in optic fiber hydrophone interrogator to demodulate the acoustic wave signal by PGC circuit.
Yang, Zun-Chyun y 楊仲群. "Miniaturized Dual-mode Double-ring Resonators for Band-pass Filter Design and Analysis". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/27565749511914280299.
Texto completo北台灣科學技術學院
機電整合研究所
95
By using the shunt-capacitance technique of dual-mode ring filter, a novel technique is proposed to miniaturize the dual-mode double-ring filter. In practice, two types of miniaturized dual-mode double-ring filter are achieved. For the configuration, the symmetry/diagonal shunt capacitors are used to improve and miniaturize the performance of the conventional dual-mode double-ring filter. Meantime, compared to the miniaturized dual-mode ring filter, the characteristics of miniaturized dual-mode double-ring filter are obtained. The better performance with lower insertion loss (1.8 dB), wider band (75MHZ), lower out-of-band rejection level (-22dB) and moderately size reduction (86%) is achieved by the miniaturized techniques for the dual-mode double-ring filters. The central frequencies with 0.4GHz of the filters can be applied for the microwave communication systems
Wu, Tai-I. y 吳臺益. "Improved Dual-mode Double-ring Resonators for Band-pass Filter Design and Analysis". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/51145286447756478056.
Texto completo清雲科技大學
電機工程研究所
95
Novel design of four improved dual-mode double-ring resonators using voltage-couples and dual-mode perturbations are proposed here. Typical DMDRR using curved couples and radial stubs, CPW-fed DMDRR using T-shaped coupling strip to couple the outer ring and with stub/notch perturbations for adjusting are studied. Two concentric rings determine the certain resonated frequencies of 1.2/2.4GHz dual bands for Wireless Video Security Links and Wireless LAN Systems communication system. The cascaded CPW-fed DMDRR exhibit a good performance including low insertion loss (2.17/ 2.01 dB), high out-of-band rejection level (-60.1/-67.5 dB) and symmetry wider band (11.44 %/13.66 %) among 1.268/2.452 GHz dual bands.
SHIE, CHING-HENG y 謝青航. "Dual-Mode Double-Ring Resonator for Microstrip Band-Pass Filter Design and Analysis". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/61123412212221939142.
Texto completo國防大學中正理工學院
電子工程研究所
91
In this thesis, the Double-Ring filter is proposed to improve the bandwidth of conventional ring filters. The possibility of the Double-Ring filter will be verified by measurements and simulations. The mode coupling techniques of the Double-Ring resonator can be classified as two types: (1) The Directive coupled-mode, (2) The Cross coupling-mode. Both of Double-Ring filter and Extended Double-Ring filter belong to the Directive coupled-mode. By the measurements and simulations the possibility of the mode coupling techniques can be verified. By this contribution the Double-Ring filter and the Extended Double-Ring filter all have the characteristic of pass-band. In the experiment design, we can fit the filter by the techniques of adjusting values, bridging capacitance and cascade-stage, and it can be served as a reference for Double-Ring filter design. From the matching techniques, the Double-Ring filter is designed and compared with Butterworth filter, Single-Ring filter and Chebyshev filter for the advantages. The measurements and the simulations are similar.
Liu, Ta-Cheng y 劉大成. "Dual-mode Double-ring Resonators with Radial-slot /Ω-shaped Perturbations for Miniaturizations". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/21813759272396999415.
Texto completo清雲科技大學
電機工程研究所
97
Two kinds of miniaturizations techniques with frequency reductive are studied in this thesis. The first one is capacitance radial-slot perturbations, and the second one is inductive Ω-shaped perturbations, both techniques are applied for the dual-mode ring and the dual-mode double-ring resonators respectively. By the perturbations and matching techniques, the single band and dual band reduction for miniaturizations are achieve. Results including surface current distributions and frequency responses are presented and discussed. First, the dual-mode double-ring resonators with radial-slot perturbations are proposed. The significant size reductions over 30 / 10 % are achieved at dual-band 1.40 / 2.12 GHz respectively. The lower insertion loss -2.14 / -1.18 dB, the higher rejection -42.02 dB and the wider bandwidth about 5.26 / 17.57% responses are presented. Second, dual-mode double-ring resonators with Ω-shaped perturbations are presented, the significant size reductions over 56 / 10% are obtainey at dual-band 1.13 / 2.11 GHz respectively. The lower insertion loss -2.49 / -0.75 dB, the higher rejection -19.93 dB and the wider bandwidth about 4.82/16.45% responses are presented. Finally, based on an identical band and keeping 31% size reductions, the frequency responses of the single-ring and double-ring are analyze. The single-ring of radial-slot and Ω-shaped are with wider bandwidth 6.89% and 5.95% and deeper rejection level -33.36 / -44.39 dB and -33.63 / -53.21 dB respectively. The double-ring of radial-slot and Ω-shaped are with wider bandwidth 8.65% and 7.5% and deeper rejection level -24.59 / -41.08 dB and 24.25 / -20.04 dB.
Bonneau, Marlene. "Re-thinking rites of passage in contemporary double-ring ceremonies in Montreal Jewish weddings". Thesis, 2002. http://spectrum.library.concordia.ca/1716/1/NQ68206.pdf.
Texto completoHuang, Han-Ming y 黃瀚民. "Design evaluation of ring-type pulse oximeter by using single and double light sources". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30667678989360863209.
Texto completo國立交通大學
影像與生醫光電研究所
101
Pulse oximeter is a non-invasive instrument used to monitor arterial oxygen saturation of haemoglobin. Even though fingertip-type pulse oximeter is popular, it is still inconvenient for long-term monitoring, in particular, under motion and action. Therefore, the development of other wearable pulse oximeters, such as ring-type pulse oximeter, is more practicable for long-term monitoring. However, the complex tissue architecture of the finger base also results in the trouble of ring-type pulse oximeter design. In this study, the practicability of ring-type pulse oximeter design with the single and double light sources was evaluated by using human tissue simulations. The effective region of measuring SpO2 by placing single and double light sources was investigated to find out the optimal design. Finally, the experiment of measuring SpO2 was also tested to validate the simulated results.
Chen, Chien-Tai y 陳建泰. "Analysis and application of the theory for multi-step falling-head double-ring test". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/36099042489734041859.
Texto completo國立成功大學
資源工程學系碩博士班
92
The double-ring test is one of the most important methods to estimate soil characters in situ. The test can be performed by either constant pressure head or falling pressure head. Constant-head double-ring test is commonly used but not suitable for highly permeable materials due to the fast dissipation of water. To overcome the limitations of the constant-head double-ring test, a novel method named as multi-step falling-head double-ring test was developed. The new method is based on Philip’s single-step falling-head theory. The proposed method is especially useful in measuring the field saturated hydraulic conductivities at different depths and suitable for sites with high permeability or macropores. HYDRUS-2D software is used to simulate multi-step falling-head infiltration tests. The effective arrival time of wetting front is determined based on the numerical results. The mid-time of the variation of potential head is found to be a good approximation to estimate the effective arrival time. By applying the new method to a hill slope site of Tsaoling in the Cingshui-river basin, the result shows that hydraulic conductivities obtained from the new method are very close to the values of core samples obtained by the constant-head test in laboratory. Obtained average hydraulic conductivity decreasing with soil depth is consistent with the soil distribution observed in field. The new method has been shown to be efficient and economic to measure undisturbed hydraulic conductivities at different depths.
Chen, Pin-hui y 陳品匯. "The Study of The Output Characteristics of a Mode-locked Fiber Double Ring Laser". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/89628773386033835118.
Texto completo國立高雄大學
電機工程學系碩士班
100
This experiment is based on fiber ring mode-locked laser pumped by 980nm laser excitation to erbium-doped fiber achieve a profile covered. At the same time the EDF be used to amplify the signal in a fiber ring laser system. There are a bandwidth filters and an electro-optical modulator be used to study the effects of fiber ring laser mode -locking characteristic. Then we change the characteristic of the system to double ring. The upside and the underside of the ring have EDFA as the source of amplifier. We comparing the same lengh with modulated frequency at 3.044MHz and 12.288MHz, and the different lengh with modulated frequency at 12.2879 MHz. Measure the optcal power and peak to peak of the time trace and the analysis of output result and its characteristics. We have two result, one is linear and the other one has threshold currnet. We can get the result what we want by controling the pumping power. We use the linear result in communicated applications, then the threshold currnet can use to control the other ring output power, to achieve optical switch.
Deng, Ping-Chun y 鄧平純. "Wide Band Dual-mode Double Slot-ring Resonators for Band-pass Filter Design and Analysis". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/08520923461540042193.
Texto completo清雲科技大學
電子工程研究所
94
The alternative configurations of improved dual-mode double ring resonator and dual-mode double slot ring resonator are introduced to improve the performance of the conventional DMDRR in this thesis. Using voltage-coupling and dual-mode perturbations with shaped coupling and radial stub are proposed for improved dual-mode double ring resonator. Meanwhile, the novel dual-mode double slot ring resonator using tree-shaped couples and perturbation stubs are developed to enhance the bandwidth sufficiently. Results including surface current distributions and frequency responses analysis are presented and discussed. The developed dual-mode double slot ring resonator with lower insertion loss -0.61 dB, wider bandwidth 93.7% BW and higher rejection band (deep to 40 dB)exhibits good wide-band performance for band-pass filter design. In addition, its coupling way is constructed efficiently in coplanar with the circuits and easy to fabricate with MIC. It can be applied to the PCS and microwave communication systems.
Chen, Jr-Hsin y 陳智信. "The Development and Application of Double Wall-Jet Ring-Disk Screen Printed Electrodes in Electroanalysis". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/30371273859338474206.
Texto completo國立中興大學
化學系所
95
The development and application of Double Wall-Jet Ring-Disk Screen Printed Electrodes (DWJ-RD-SPE) is focused on this study. The system contains a disposable Screen-Printed Ring-Disk carbon electrode together with BAS thin-layer Wall-Jet flow cell for flow injection analysis. First, the DWJ-RD-SPEs were fabricated with a built-in three-electrode pattern of alternating printed-layer of carbon, silver, and insulator on a non-conductive polypropylene substrate. By controlling the layers of ring electrode screen printed, we can control the height of ring electrode, thus making higher collection efficiency possible. Then we eliminated other factors that may affect the collection efficiency of the DWJ-RD-SPE, and proved that the double Wall-Jet effect is the main effect for the even higher collection efficiency. By applying this newly developed electrodes to iodine-iodide oxidation-reduction system, we can prove the double Wall-Jet effect again. Second, we report here an application of a disposable Screen-Printed Ring-Disk carbon electrodes (RD-SPE) for sensitive determination of five aminoglycosides. The electrogenerated bromine at the disk electrode of the RD-SPE can react with aminoglycosides and hence the inhibited collect current at the ring electrode can be used for determination of aminoglycosides by flow injection analysis (FIA). Under the optimal conditions of aminoglycoside determination, the RD-SPE shows a linear calibration range of 1-100 uM
Chiu, Chung-Yu y 邱中毓. "Study on Rotating Compression Forming of Double-Layer Bounded Clad Ring with Constant Shear Friction". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/72511582176022315603.
Texto completo國立屏東科技大學
機械工程系所
101
This study assumes the interface friction between dies and bounded double-layer clad ring as constant shear friction considering the rotation of double-layer bounded clad ring to establish various rotating compression forming analysis models based on the slab method and finite element method. The slab method can derive theoretical analysis model; the finite element software (DEFORM-3D) can perform the finite element simulation to obtain the optimal forming parameters, to explore effectively the stress field and deformation behaviour of the double-layer clad ring rotating compression forming. Besides, the compression pressure, the whole radial stress of clad ring, the radial stress for each layer, the compression force and the rotating torque can be exactly calculated. Moreover, the rotating compression forming experiment of the double-layer clad ring is carried out practically to measure the compression forces and the inner and outer surfaces of double-layer clad ring. Compression forces and frictional calibration curves between analysis and experiment are compared to verify the acceptance of this study. The plastic forming analysis models established by the study can effectively determine different characteristics of double-layer clad ring rotating compression forming, it can be offered to industries for technology establishment of rotating compression forming.
Teng, Chung-ting y 鄧仲廷. "Effect of spin-orbit interaction on the electronic energy levels in a concentric quantum double ring". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/29158681146388328625.
Texto completo國立成功大學
物理學系碩博士班
97
In this thesis, we proposed a theoretical model to study the effect of the spin-orbit interaction on the electronic energy levels in a concentric quantum double ring, which has been successfully fabricated lately by self-assembly technique. We first analyzed the matrix elements of the interactions, and then diagonalized numerically the Hamiltonian of an electron in a semiconductor quantum double ring subjected to the magnetic flux and Rashba spin-orbit interaction. We found that the spin splitting of the electron energy levels was produced by the system inversion asymmetry(the Rashba term). The multi-zigzag periodic structures were revealed via Aharonov-Bohm energy spectrum. In addition, we also investigated the changes of the energy spectra of a concentric quantum double ring with either one sectorial barrier or different strength of Rashba spin-orbit interaction between inner and outer ring.
Zeng, Bing-Hao y 曾炳豪. "Double-ring Slot Antenna with Tree-Shaped Coupling Strip for WLAN Dual-Band Design and Applications". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/55874828485068759990.
Texto completo清雲科技大學
電機工程研究所
94
Three novel design of double-ring slot antenna with tree-shaped coupling strip for 2.4/5 GHz dual-band applications is presented in this thesis. Proposed two concentric slot rings determine the certain resonated frequencies of 5 GHz bands and the inner circular disk depicts the range of 2.4 GHz. Designed a tree-shaped coupling strip with branches to couple the inner circular disk and with leaves to couple the double ring slot respectively, therefore, it can enhances the response of the bands with impedance matching techniques. Its operations simultaneously cover two distinct broad-band responses of 2.4 GHz band and 5 GHz band. It is a compact and available microstrip antenna for IEEE 802.11a/b/g WLAN’s and HiperLAN2 applications. In field analysis, two-cut patterns with broadside pattern at 2.4 GHz band and the array patterns at 5 GHz band are presented in the x-z cut, and the quasi-omnidirectional patterns are observed on two bands in the y-z cut, and the active distributions of real Poynting vector are obtained to present the performance of the novel tree-shaped coupling strip for the designed antenna. In practice, antenna gains with well responses are presented at four resonant frequencies in resonant bands. Both simulation and measurement results agreed with the verified frequency responses and radiation characteristics.
Tsou, Yu-Che y 鄒有哲. "Deformation and Circularity for Machine Control Ring on Optimization of the Double Quality Using Taguchi Method". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/q8389p.
Texto completo龍華科技大學
機械工程系碩士班
107
To qualify the final molded products are approved & doable for the Lab, We can find out the best molding parameter for quality to improve the plastic and tooling feature. We are searching POM material for the mechanical gear parts, It was included teflon20%, excellent lubrication & chemical resistance, & the highest impact strength, It has a deformation & circularity stability, We can use Taguchi Method Lab flow chart L9(34), to in-put molding-injection process, Then use Optical Vision Measure to read dimensions data after lab completed. We can add Lab data into Taguchi Method for analysis, then we can get a excellent deformation & circularity combination, for example The injection 10sec, holding pressure, cooling time 35sec, barrel temperature 205°C, Based on this molded parameter will get a best SN evaluation. Then we can use best deformation & circularity data to proceed with SN evaluation to proof , deformation reading 69.692, Actual SN reading 68.820, circularity evaluation reading 26.538, Actual SN reading 26.153, We finally can find out the deformation and circularity SN evaluation will very close to the actual SN evaluation. We can provide this excellent mechanical properties for the company reference, also the Taguchi Method with all data analysis can be follow for the future new products applications.
Chu, Pei-Chun y 朱培均. "Analysis and Design of Planar Slot-Line Four Ports Crossover and Planar Double Ring Eight Ports Crossover". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/q2yv7h.
Texto completo國立中正大學
電機工程研究所
103
The thesis includes six chapters,The first chapter primarily introduce our motivation of research and discussion document. In second chapter will introduce the basic theory detaily that relative to our research. Transmission line (ABCD) matrix、S parameter theory analysis and even odd mode analysis will be introduce sequentially. Then we will introduce crossover in third chapter. Branch line coupler will introduce first, introducing its basic theory and history. After that, we will introduce the traditional crossover which series by two branch line couplers. In the fourth chapter, a planar slot line crossover will introduced, including integral theory and implement. Then, an eight ports crossover which has four channels will be introduced in chapter five. And we will implement two kind of eight ports crossovers. These two crossovers are little deferent in design parameter. In these chapter, the integral theory also included. The conclusion is in chapter six.
Wang, Jhih-Wei y 王志偉. "CPW-fed Dual-mode Double Square-loop/Ring Resonators for Multi-band and Wide-band Filter Design". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/69899933597144294495.
Texto completo清雲科技大學
電子工程系所
97
Novel design of dual-mode double square-loop/ring resonators using CPW-fed and dual-mode perturbations are applied for multi-band and wide-band applications. In the design, using CPW-fed with twin-T structure coupling to DMDSLR/DMDRR for dual-band, tri-band, quad-band, and wide-band are proposed in this thesis. For practice, due to two concentric rings determine the certain resonated frequencies, we can get 0.9/ 1.2/ 1.8/ 2.4 GHz quad bands in all and it can be applies to GSM system, wireless video security links and Wireless LAN systems communication system. The quad-band be excited with asymmetric folded CPW-fed of DMDSLR. It exhibits a good performance including lower insertion loss (2.52/ 1.93/ 1.06/ 0.76 dB), higher out-of-band rejection level (-45/ -51/ -38/ -32/ -35 dB) and symmetry wider band (3.6 %/ 6.2 %/ 13.9 %/ 16.1 %) among 0.94/ 1.29/ 1.9/ 2.32 GHz quad bands respectively. In addition, we design the double square-loop on Aluminum Nitride (AIN) substrate, to have a wide-band bandpass response, with lower insertion loss (0.97 dB), deeper transmission zero level (35.4/ 34.6 dB) and wider bandwidth (43.22 %).
Su, Ya-fang y 蘇雅芳. "The Size-Reduced Double-Layer Leaky-wave Microstrip Antenna with Semi-Ring Structure for Circular Polarization Applications". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/70030022508459205106.
Texto completo義守大學
電子工程學系碩士班
97
This thesis applies PEC walls to reduce antenna size of a double-layer leaky-wave microstrip antenna with semi-ring structures which has the characteristics of broad-band operation and circular polarization (CP) radiation. From design point of view, proper antenna dimensions and operating frequency band are the key considerations to avoid unaccepted side-lobe radiation. After proper design, the results show that the size of this leaky-wave antenna is reduced sixty percent significantly, the characteristics of a general leaky-wave antenna still maintain. The inner radius at lower-layer and gap width variation of double-layer structure also increase design freedom, thus this antenna has adjustable broad-band CP and acceptable radiation pattern. As a result, CP bandwidth can be adjusted easily for different demands of application. The cavity model with modification is applied to analyze antenna performance, and the computer-aid simulations and semi-empirical method improve numerical accuracy, as well as verify design concept. And the step-by-step arrangement of investigation here and the adjustment of antenna dimensions are used to investigate antenna performances from all aspects; thus, the data in this thesis has become more reliable. The microstrip structure of this antenna itself owns the advantage to integrate with MMIC components as expected. If the technique of this size reduction can be applied to other complicated structure, the design concept is more valuable. The cavity model can be directly applied to structure with different substrate materials, provide that the cavity regions can be modified appropriately.
Wu, Shao-chin y 吳劭慶. "The Investigation of Double-Layers Leaky-wave Microstrip Antennaa with Semi-Ring Structure for Circular Polarization Application". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/99288538607714605325.
Texto completo義守大學
電子工程學系碩士班
95
The CP (circularly polarization) antenna has been popular in the long distance communication due to its high noise-tolerant capability. Among many CP antennas, the semi-ring leaky-wave antenna with double-layers overcomes the shortcoming of traditional spiral antennas, and it can radiate broad-band CP electromagnetic wave only with a simple single-feeding. The advantages of the double-layer structure can easily match input impedance of antenna, and the CP band is adjustable based on demands. But the analysis on this antenna is not completed due to its complicated structure, and application is thus limited. Therefore, the purpose of this thesis is to establish the analysis theory for this CP antenna, as well as understand its concept and characteristics. First, this thesis introduces the CP concept by theoretical data. Later, the analysis of a single-layer semi-ring antenna is applied to double-layers ones. After appropriate process, the use of cavity model effectively obtains antenna characteristics, including propagation behavior, electrical distribution, radiation pattern and CP performance. The agreement between theory and simulation proves the validity of proposed method here. Besides, this thesis does not only summarizes the flow chart to design this kind of CP antenna, but analysis results also confirm that this antenna can operate in broad CP bands. Moreover, the high degree of freedom from structure enables the antenna to have different frequency bands for operation. By the modification of simulation, those results obtained by cavity model are close to reality, the accuracy of results eases the use of this antenna. This thesis establishes the fundamental theorem for double-layers semi-ring leaky-wave antennas, and the provided data and results are also useful for future applications.
Hu, Chih-Ting y 胡誌廷. "A New-Type Double Feedback LC-Tank VCO and The Study of Temperature Compensation Effect with Ring VCO". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/39001771802162851895.
Texto completo國立臺灣科技大學
電子工程系
93
This thesis is mainly composed of three topics. The first topic is the design, implementation and measurement of a ring voltage-controlled oscillator (VCO) with temperature compensation structure. The second topic is the design, implementation and measurement of a 2.4GHz LC-tank VCO. The third topic is the design, implementation and measurement of a 2.4GHz frequency divider. In first two circuits of whole three designs, ring VCO with temperature compensation structure and 2.4GHz LC-tank, they are fabricated by TSMC 0.35um CMOS 2P4M, except the 2.4GHz frequency divider is fabricated by UMC 0.18um COMS 1P6M. All circuits in this thesis are simulated using by Spectre RF CAD. In future work, we hope to integrate the concepts of oscillator and divider, and could be utilized in the phase-locked loop and so on.
Lin, Wei-Yang y 林緯洋. "Double ring-opening cationic polymerization mechanisms of spiro orthoesters and the volume-expanded eigenvalue analysis of the polymers thus formed". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/7y8t3w.
Texto completo國立臺灣科技大學
材料科學與工程系
99
A corresponding stereoregular polyether-esters, poly(trans-2-oxocyclohexyl butyrate) (Entry 8c’), poly(trans-2-oxocyclohexyl pentanoate) (Entry 9c’), poly(trans-2-oxocyclohexyl hexanoate) (Entry 10c’) with trans configuration were obtained, when the spiro-orthoester (SOE) monomers, cis-2,3-tetramethyl-ene-1,4,6-trioxaspiro[4.4]nonane (Entry 8), cis-2,3-tetramethylene-1,4,6-trioxaspiro[4.5]decane (Entry 9), and cis-2,3-tetramethylene-1,4,6-trioxaspiro[4.6]undecane (Entry 10) were added to the UV-exposed (λmax: 254nm) (4-octylphenyl)phenyl-iodoniumhexafluroantimonate (OPIA)/anthracene (AN) initiating system to undergo the regiospecific polymerization. In the contrary, when Entry 8, Entry 9, and Entry 10 underwent conventional cationic polymerization, respectively, using SnCl4 as an initiator, the stereoregular polyether-esters, poly(cis-2-oxocyclohexyl butanoate) (Entry 8a’) and poly(cis-2-oxocyclohexyl- pentanoate) (Entry 9a’), with cis configuration were obtained by the polymerization of Entry 8 and 9, while the stereoregular polyether-ester, poly(trans-2-oxocyclohexyl hexanoate) (Entry 10a’), with trans configuration was obtained by the polymerization of Entry 10. The structure and volume change of the products were identified and the mechanism of respective reaction was studied and deduced. The volume of the trans configurational, stereoregular products are expansion, while volume of the cis configurational, stereoregular products are shrink. The configureational eigenvalues of the bivalent trans- and cis-1,2-cyclohexyl groups in the respective repeating unit are calculated as 84.10±1.54 and 76.94±0.04 cm3/mol by additive group contribution method, and was demonstrated having great influence on volume expansion of the polymer produced. Thus, these changes could be clarified by approach the quantum chemistry calculations, such as activation enthalpy, intermolecular distances, and chain-end distances of the polymer . The calculation result was showed excellent consistent with experiment parameter.
Dosanjh, Pinder S. "Microwave surface resistance measurements of YBa2Cu3o6+x single crystals and melt textured slabs employing a niobium double split-ring resonator". Thesis, 2001. http://hdl.handle.net/2429/11518.
Texto completoZheng, Jingyang. "A study of mechanical behaviour of the double-row tapered ring bearing for the main shaft of a direct-drive wind turbine". Thesis, 2020. http://hdl.handle.net/10453/148813.
Texto completoDouble-row tapered roller bearings (TRBs) are one of the main components of a modern direct-drive wind turbines, TRBs are commonly used to support the main shafts of wind turbines since fault scan lead to the malfunctions and downtime of wind turbines. In recent decades, some numerical approaches have been proposed for calculating the contact force and pressure distribution of double-row TRBs. Nevertheless, most of the existing studies failed to consider angular misalignment between the inner and outer rings as well as the friction force between the rollers and raceways. A fatigue life analysis of roller bearings is typically performed for bearings under constant rotating speed and invariant loading conditions. The bearings used in floating direct-drive wind turbines, they often experience oscillating motions with varying loading patterns ; thus, for which the standard fatigue life analysis is not valid in this case due to the presence of fluctuating loads. Notably, aquasi-static state does not exist for bearing in the actual operating condition. Since the dynamic model is unable to show the detailed dynamic mechanic al behaviour of double-row TRBs such as the contact are a stress, total displacement of bearing components of bearings, velocity and acceleration of rolling elements (by considering the combined radial and axial load), the angular misalignment of roller and inner ring, roller skewing conditions, components vibration characteristics and roller-end flange friction a new general dynamic model was proposed in this section based on the previous studies. This is because most of the previous studies are unsuitable for real working conditions. However, to verify the proposed dynamic model, a simplified finite element analysis (FEA) model was also established using the commercial software ANSYS Work bench. Hence, the data obtained from this dynamic behaviour analysis can be used to implement the fatigue life prediction for the double-row TRBs, which can significantly benefit their design and manufacturing. This thesis presents a comprehensive quasi-static model to investigate the internal load and contact pressure distribution in a double-row TRB by considering the angular misalignment, the combined external loads and friction force. Most importantly, the presented numerical model was validated by other published references and the simplified FEA model. First of all, it was found that a small misalignment angle between the inner and outer rings can cause a significant change in the magnitude and distribution of the contact force and pressure. A double-row TRB with a crowned roller profile exhibits a substantial improvement in contact pressure distribution by eliminating the contact pressure. Peak contact pressure can be significantly reduced on a roller with crowned profile, even with a misaligned bearing. Comparisons of the simulated contact loads and pressure distributions demonstrate that need to consider angular misalignment and friction force in the modelling of large size and heavy-load double-row TRBs. Furthermore, this thesis presents a fatigue life analysis for double-row TRBs under oscillating external load and speed conditions in which the double-row TRB was used to support the main shaft of a large modern direct -drive wind turbine. Meanwhile, the proposed comprehensive and quasi-static model of the double-row TRB outlines the internal load distribution of rollers. The contact pressure of rollers is then provided based on an iterative scheme using the elastic contact model. Thereafter, the basic rating life of the double-row TRB under an oscillating external load and speed is provided to calculate the fatigue life. Numerical simulations were also performed to investigate the effects of the oscillating load and speed, angular misalignment, and internal clearance on the fatigue life of this bearing. Finally, the simulation results of the dynamic model analysis indicated that the combined radial load and pure radial load have a significant effect on the vibration of rollers and the inner ring of double-row TRBs in a floating direct-drive wind turbine. Meanwhile, the angular misalignment of the inner ring also affects the vibration of the rollers and the inner ring itself. With an increase in the misalignment angle, the vibration of roller elements became increasingly apparent. The vibration frequency of rollers and the inner ring gradually decreased with an increasing misalignment angle. Additionally, the vibration of components in the double-row TRBs is sensitive to the initial axial preload.
PICCIAFUOCO, TOMMASO. "On the estimation of saturated hydraulic conductivity: from local to field scale". Doctoral thesis, 2019. http://hdl.handle.net/2158/1171691.
Texto completoVamadevan, Varatharajan. "Organization of Glucan Chains in Starch Granules as Revealed by Hydrothermal Treatment". Thesis, 2013. http://hdl.handle.net/10214/7240.
Texto completo