Desenvolvimento inicial e crescimento in vitro de Cattleya violacea (Kunth) Rolfe em diferentes concentrações de sacarose

O presente estudo teve por objetivo analisar os aspectos da germinação e avaliar o efeito de concentrações de sacarose no crescimento in vitro de Cattleya violacea. Sementes provenientes de cápsulas fechadas foram semeadas em meio de cultura Murashige e Skoog (MS) e a morfologia externa da semente à plântula foi fotodocumentada em estereomicroscópio e microscópio eletrônico de varredura. Plântulas com 90 dias após a semeadura foram repicadas em meio de cultura ½ MS (com metade da concentração de macronutrientes) com diferentes concentrações de sacarose (0, 10, 20, 30 e 40 g L-1), incubadas nas mesmas condições in vitro por mais 150 dias e em seguida as plântulas foram avaliadas quanto ao número de raízes, comprimento da maior raiz, número de folhas, comprimento da parte aérea, massa fresca e seca total. Os dados biométricos foram submetidos à análise estatística e a eles ajustadas curvas de regressão. As sementes apresentaram testa reticulada com uma extremidade micropilar (aberta) e calazal (fechada); o embrião originou uma estrutura tuberiforme clorofilada denominada protocormo que pode apresentar rizóides, folíolos e quando provido de raiz é considerado plântula. A ausência de açúcar ou a maior concentração avaliada de sacarose foram prejudiciais ao crescimento da planta. A concentração de 27 g L-1 proporcionou maior crescimento in vitro possibilitando maior eficiência para a propagação massal dessa espécie de elevado potencial ornamental.

Auxin-producing bacteria isolated from the roots of Cattleya walkeriana, an endangered Brazilian orchid, and their role in acclimatization

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uso de subprodutos de carvão vegetal na formação do porta-enxerto limoeiro 'Cravo' em ambiente protegido

O trabalho teve como objetivo avaliar o efeito do uso de fino de carvão no substrato e da aplicação de extrato pirolenhoso no substrato e na planta sobre o desenvolvimento de porta-enxertos de limoeiro 'Cravo' (Citrus limonia Osbeck) cultivados em ambiente protegido. O experimento foi desenvolvido no delineamento em blocos casualisados, com análise em esquema fatorial 3 x 2 x 3, sendo: 3 proporções de fino de carvão (0, 100 e 200 cm³ dm-3) em mistura com substrato comercial, 2 concentrações de extrato pirolenhoso (0 e 20 cm³ dm-3) misturadas no substrato (240 cm³ por dm³ de substrato) e 3 concentrações de extrato pirolenhoso (0, 5 e 10 cm³ dm-3) pulverizadas na parte aérea, em 4 repetições. Aos 150 e 180 dias após o plantio foram realizadas avaliações do desenvolvimento das plantas. As misturas de fino de carvão e substrato comercial contendo fino de carvão na proporção de 100 cm³ dm-3 não influíram no desenvolvimento de porta-enxertos de limoeiro 'Cravo' , porém, na proporção de 200 cm³ dm-3 prejudica o desenvolvimento dos mesmos. O umedecimento pré-plantio do substrato com solução diluída (20 cm³ dm-3) de extrato pirolenhoso ou pulverização da parte aérea das plantas com soluções a 5 e 10 cm³ dm-3 provoca redução do desenvolvimento de porta-enxertos de limoeiro 'Cravo' .

Emergência e desenvolvimento de plântulas de cultivares de marmeleiro para uso como porta-enxertos

O presente trabalho tee como objetivo estudar a emergência e o desenvolvimento de plantas de marmeleiro, com potencial para serem utilizadas como porta-enxertos. O trabalho foi desenvolvido no Centro APTA Frutas/IAC, de maio/05 a janeiro/06. Sementes dos marmeleiros 'Mendoza INTA-37', 'Provence', 'Portugal' e 'Japonês' foram extraídas de frutos maduros, lavadas em água corrente, secas à sombra por 48 h e estratificadas a frio por 20 dias. em seguida, foram semeadas em bandejas de poliestireno (72 células, capacidade de 120 cm³/célula) contendo a vermiculita como substrato. Foi feito contagem da porcentagem de emergência após 30 dias da semeadura, a cada 10 dias, em um total de quatro coletas. em seguida, foi retirada uma amostra de 10 plântulas por repetição e avaliados a altura média da parte aérea, nº de folhas, massa seca média da parte aérea e das raízes. Foram ainda separados 10 plântulas uniformes e representativos de cada repetição e transplantados para sacos plásticos (capacidade de 3 L) contendo como substrato solo + esterco de curral curtido + areia (1:1:1 v/v). As plântulas permaneceram em viveiro telado (sombrite 50%), sendo irrigadas periodicamente. A cada 30 dias, foram mensurados a altura e o diâmetro das plântulas até o final da sexta avaliação (após 180 dias do transplantio). Concluiu-se que o marmeleiro 'Japonês' apresenta maior porcentagem de emergência (70%), altura das plântulas (111,83 cm) e diâmetro (0,7 cm), possuindo maior performance e uma excelente alternativa como porta-enxerto para marmeleiros.

Análise e projeto de superfícies seletivas de frequência com elementos pré-fractais para aplicações em comunicações indoor

In this thesis, a frequency selective surface (FSS) consists of a two-dimensional periodic structure mounted on a dielectric substrate, which is capable of selecting signals in one or more frequency bands of interest. In search of better performance, more compact dimensions, low cost manufacturing, among other characteristics, these periodic structures have been continually optimized over time. Due to its spectral characteristics, which are similar to band-stop or band-pass filters, the FSSs have been studied and used in several applications for more than four decades. The design of an FSS with a periodic structure composed by pre-fractal elements facilitates the tuning of these spatial filters and the adjustment of its electromagnetic parameters, enabling a compact design which generally has a stable frequency response and superior performance relative to its euclidean counterpart. The unique properties of geometric fractals have shown to be useful, mainly in the production of antennas and frequency selective surfaces, enabling innovative solutions and commercial applications in microwave range. In recent applications, the FSSs modify the indoor propagation environments (emerging concept called wireless building ). In this context, the use of pre-fractal elements has also shown promising results, allowing a more effective filtering of more than one frequency band with a single-layer structure. This thesis approaches the design of FSSs using pre-fractal elements based on Vicsek, Peano and teragons geometries, which act as band-stop spatial filters. The transmission properties of the periodic surfaces are analyzed to design compact and efficient devices with stable frequency responses, applicable to microwave frequency range and suitable for use in indoor communications. The results are discussed in terms of the electromagnetic effect resulting from the variation of parameters such as: fractal iteration number (or fractal level), scale factor, fractal dimension and periodicity of FSS, according the pre-fractal element applied on the surface. The analysis of the fractal dimension s influence on the resonant properties of a FSS is a new contribution in relation to researches about microwave devices that use fractal geometry. Due to its own characteristics and the geometric shape of the Peano pre-fractal elements, the reconfiguration possibility of these structures is also investigated and discussed. This thesis also approaches, the construction of efficient selective filters with new configurations of teragons pre-fractal patches, proposed to control the WLAN coverage in indoor environments by rejecting the signals in the bands of 2.4~2.5 GHz (IEEE 802.11 b) and 5.0~6.0 GHz (IEEE 802.11a). The FSSs are initially analyzed through simulations performed by commercial software s: Ansoft DesignerTM and HFSSTM. The fractal design methodology is validated by experimental characterization of the built prototypes, using alternatively, different measurement setups, with commercial horn antennas and microstrip monopoles fabricated for low cost measurements

Desenvolvimento de um ressoador retangular de fenda com múltiplas camadas de substrato e com utilização de material PBG para sistema de comunicação sem fio

In the globalized world modern telecommunications have assumed key role within the company, causing a large increase in demand for the wireless technology of communication, which has been happening in recent years have greatly increased the number of applications using this technology. Due to this demand, new materials are developed to enable new control mechanisms and propagation of electromagnetic waves. The research to develop new technologies for wireless communication presents a multidisciplinary study that covers from the new geometries for passive antennas, active up to the development of materials for devices that improve the performance at the frequency range of operation. Recently, planar antennas have attracted interest due to their characteristics and advantages when compared with other types of antennas. In the area of mobile communications the need for antennas of this type has become increasingly used, due to intensive development, which needs to operate in multifrequency antennas and broadband. The microstrip antennas have narrow bandwidth due to the dielectric losses generated by irradiation. Another limitation is the degradation of the radiation pattern due to the generation of surface waves in the substrate. Some techniques have been developed to minimize this limitation of bandwidth, such as the study of type materials PBG - Photonic Band Gap, to form the dielectric material. This work has as main objective the development project of a slot resonator with multiple layers and use the type PBG substrate, which carried out the optimization from the numerical analysis and then designed the device initially proposed for the band electromagnetic spectrum between 3-9 GHz, which basically includes the band S to X. Was used as the dielectric material RT/Duroid 5870 and RT/Duroid 6010.LM where both are laminated ceramic-filled PTFE dielectric constants 2.33 and 10.2, respectively. Through an experimental investigation was conducted an analysis of the simulated versus measured by observing the behavior of the radiation characteristics from the height variation of the dielectric multilayer substrates. We also used the LTT method resonators structures rectangular slot with multiple layers of material photonic PBG in order to obtain the resonance frequency and the entire theory involving the electromagnetic parameters of the structure under consideration. xviii The analysis developed in this work was performed using the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transverse to the real direction of propagation z), thus treating the general equations of the fields electric and magnetic and function. The PBG theory is applied to obtain the relative permittivity of the polarizations for the sep photonic composite substrates material. The results are obtained with the commercial software Ansoft HFSS, used for accurate analysis of the electromagnetic behavior of the planar device under study through the Finite Element Method (FEM). Numerical computational results are presented in graphical form in two and three dimensions, playing in the parameters of return loss, frequency of radiation and radiation diagram, radiation efficiency and surface current for the device under study, and have as substrates, photonic materials and had been simulated in an appropriate computational tool. With respect to the planar device design study are presented in the simulated and measured results that show good agreement with measurements made. These results are mainly in the identification of resonance modes and determining the characteristics of the designed device, such as resonant frequency, return loss and radiation pattern

Um estudo de estruturas com PBG e fotônica

One of the objectives of this work is the ana1ysis of planar structures using the PBG (photonic Bandgap), a new method of controlling propagation of electromagnetic waves in devices with dielectrics. Here the basic theory of these structures will be presented, as well as applications and determination of certain parameters. In this work the analysis will be performed concerning PBG structures, including the basic theory and applications in planar structures. Considerations are made related to the implementation of devices. Here the TTL (Transverse Transmission Line) method is employed, characterized by the simplicity in the treatment of the equations that govern the propagation of electromagnetic waves in the structure. In this method, the fields in x and z are expressed in function of the fields in the traverse direction y in FTD (Fourier Transform Domain). This method is useful in the determination of the complex propagation constant with application in high frequency and photonics. In this work structures will be approached in micrometric scale operating in frequencies in the range of T erahertz, a first step for operation in the visible spectra. The mathematical basis are approached for the determination of the electromagnetic fields in the structure, based on the method L TT taking into account the dimensions approached in this work. Calculations for the determination of the constant of complex propagation are also carried out. The computational implementation is presented for high frequencies. at the first time the analysis is done with base in open microstrip lines with semiconductor substrate. Finally, considerations are made regarding applications ofthese devices in the area of telecommunications, and suggestions for future

Análise de antenas de microfita em rampa com múltiplas camadas dielétricas

The present work deals with the ana1ysis of microstrip patch antennas printed on tapered dielectric substrates. We investigate the influence ofthe substrate height variations on the properties of configurations such as microstrip patch antennas, microstrip patch antennas with overlay and suspendeô microstrip patch antennas. The dielectric substrates can be isotropic or anisotropic ones. This accurate analysis is based on the full-wave formulation. It is carried out initially for the determination of the impedance matrix, through the use of the spectral¬domain immitance approach. We use a model based on a segmentation of the considered line into uniform microstrip line subsections. Normalized phase constants and characteristic impedances are obtained by means of the Galerkin numerical technique. Then, the cascaded combination of the uniform microstrip subsections are analyzed through an interactive procedure. Numerical results are presented for the input reflection coefficient, voltage standing wave ratio, resonant frequency, and radiation pattems ofthe E_plane and H-plane diagrams. It is found that the variations in the substrate height profile produce a great influence on the bandwidth of microstrip antennas. This procedure gives bandwidth improvements without altering considerably the resonant frequency. Furthermore, the tapered microstrip antenna can be used as a lightweight altemative for bandwidth control and to eXtend the use of microstiip antenna technology to a wider variety of applications. Finally, suggestions for the continuity of this work are presented

Antenas planares multicamadas com materiais supercondutores e fotônico para comunicações móveis

Recently, planar antennas have been studied due to their characteristics as well as the advantages that they offers when compared with another types of antennas. In the mobile communications area, the need for this kind of antennas have became each time bigger due to the intense increase of the mobile communications this sector. That needs of antennas which operate in multifrequency and wide bandwidth. The microstrip antennas presents narrow bandwidth due the loss in the dielectric generated by radiation. Another limitation is the radiation pattern degradation due the generation of surface waves in the substrate. In this work some used techniques to minimize the disadvantages (previously mentioned) of the use of microstrip antennas are presented, those are: substrates with PBG material - Photonic Bandgap, multilayer antennas and with stacked patches. The developed analysis in this work used the TTL - Transverse Transmission Line method in the domain of Fourier transform, that uses a component of propagation in the y direction (transverse to the direction real of propagation z), treating the general equations of electric and magnetic field as functions of Ey and Hy. One of the advantages of this method is the simplification of the field equations. therefore the amount of equations lesser must the fields in directions x and z be in function of components Ey and Hy. It will be presented an brief study of the main theories that explain the superconductivity phenomenon. The BCS theory. London Equations and Two Fluids model will be the theories that will give support the application of the superconductors in the microfita antennas. The inclusion of the superconductor patch is made using the resistive complex contour condition. This work has as objective the application of the TTL method to microstrip structures with single and multilayers of rectangular patches, to obtaining the resonance frequency and radiation pattern of each structure

Modulação quantizada para sistemas com codificação wavelet sujeitos ao desvanecimento rayleigh

Wavelet coding is an efficient technique to overcome the multipath fading effects, which are characterized by fluctuations in the intensity of the transmitted signals over wireless channels. Since the wavelet symbols are non-equiprobable, modulation schemes play a significant role in the overall performance of wavelet systems. Thus the development of an efficient design method is crucial to obtain modulation schemes suitable for wavelet systems, principally when these systems employ wavelet encoding matrixes of great dimensions. In this work, it is proposed a design methodology to obtain sub-optimum modulation schemes for wavelet systems over Rayleigh fading channels. In this context, novels signal constellations and quantization schemes are obtained via genetic algorithm and mathematical tools. Numerical results obtained from simulations show that the wavelet-coded systems derived here have very good performance characteristics over fading channels

Ressoador retangular defenda com quatro camadas fotônicas

Recently, planar antennas have attracted interest due to its characteristics as well as the advantages they offer compared to other types of antennas. In the area of mobile communications the need for such antennas has become increasingly intense due to development, which requires antennas that operate in multifrequency and broadband. The microstrip antennas have narrow bandwidth due to losses in the dielectric caused by irradiation. Another limitation is the radiation pattern degradation due to generation of surface waves in the substrate. Some techniques are being developed to minimize this bandwidth limitation, as is the case in the study of type materials PBG - Photonic Band Gap, to compose the dielectric material. The analysis developed in this work were performed with use of the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transerve real direction of propagation z), thus treating the general equations of the fields electric and magnetic fields as a functions of y E and Hy . This work has as main objective the method LTT structures resonator line slot with four layers of material photonic PBG, for obtaining the complex resonant frequency and efficiency of this structure. PBG theory is applied to obtain the relative permittivity for the substrate biases sep compounds photonic material. Numerical-computational results in graph form in two dimensions for all the analysis are presented for the proposed structures that have photonic materials, as substrates

Acoplador e linha de lâmina unilateral e bilateral com substrato fotônico

The aim of this work is to characterize and use the characteristic parameters of the planar structures constructed with fin lines looking for their applications in devices, using PBG Photonic Band Gap photonic materials as substrate, operating in the millimeter and optic wave bands.The PBG theory will be applied for the relative permittivity attainment for the PBG photonic substrate s and p polarizations. The parameters considered in the structures characterization are the complex propagation constant and the characteristic impedance of unilateral and bilateral fin lines that were obtained by the use of the TTL Transverse Transmission Line Method, together with the Method of the Moments. The final part of this work comprises studies related to the behavior of the asymmetric unilateral fin line coupler with photonic substrate. This research opens perspectives for new works in this modern area. Numerical results are shown by means of bi-dimensional and three-dimensional graphics. Conclusions and suggestions for future works are also presented

Otimização do controle eletrônico do diagrama de radiação de arranjos de antenas usando algoritmos genéticos com codificação real

Antenna arrays are able to provide high and controlled directivity, which are suitable for radiobase stations, radar systems, and point-to-point or satellite links. The optimization of an array design is usually a hard task because of the non-linear characteristic of multiobjective, requiring the application of numerical techniques, such as genetic algorithms. Therefore, in order to optimize the electronic control of the antenna array radiation pattem through genetic algorithms in real codification, it was developed a numerical tool which is able to positioning the array major lobe, reducing the side lobe levels, canceling interference signals in specific directions of arrival, and improving the antenna radiation performance. This was accomplished by using antenna theory concepts and optimization methods, mainly genetic algorithms ones, allowing to develop a numerical tool with creative genes codification and crossover rules, which is one of the most important contribution of this work. The efficiency of the developed genetic algorithm tool is tested and validated in several antenna and propagation applications. 11 was observed that the numerical results attend the specific requirements, showing the developed tool ability and capacity to handle the considered problems, as well as a great perspective for application in future works.

Predicao de campo em comunicacao sem fio

Even living in the XXI century are still some difficulties in access to broadband Internet in several Brazilian cities, due to the purchasing power of people and lack of government investment. But even with these difficulties, we seek to encourage the use of wireless technology, which is based on the IEEE 802.11b protocol - also known as Wi-Fi (Wireless Fidelity) Wireless Fidelity Communications, having wide range of commercial applications in the world market, nationally and internationally. In Brazil, this technology is in full operation in major cities and has proved attractive in relation to the access point to multipoint and point-to-point. This paper is a comparative analysis of prediction field, using models based on the prediction of propagation loss. To validate the techniques used here, the Okumura-Hata models, modified Okumura-Hata, Walfisch-Ikegami model, were applied to a wireless computer network, located in the neighborhood of Cajupiranga in the city of Melbourn, in Rio Grande do Norte . They are used for networking wireless 802.11b, using the Mobile Radio to measure signal levels, beyond the heights of the antennas and distances from the transmitter. The performance data versus distance are added to the graphs generated and compared with results obtained through calculations of propagation models

Análise espectral de reflectarrays com substratos de duas camadas dielétricas anisotrópicas uniaxiais

Recently, an amazing development has been observed in telecommunication systems. Two good examples of this development are observed in mobile communication and aerospace systems. This impressive development is related to the increasing need for receiving and transmitting communication signals. Particularly, this development has required the study of new antennas and filters. This work presents a fullwave analysis of reflectarrays. The considered structures are composed by arrays of rectangular conducting patches printed on multilayer dieletric substrates, that are mounted on a ground plane. The analysis is developed in the spectral domain, using an equivalent transmission line method in combination with Galerkin method. Results for the reflection coefficient of these structures are presented and compared to those available in the literature. A good agreement was observed. Particularly, the developed analysis uses the transmission lines theory in combination with the incident potentials and the field continuity equations, at the structures interfaces, for obtaining the scattered field components expressions as function of the patch surface currents and of the incident field. Galerkin method is used to determine the unknown coefficients in the boundary value problem. Curves for the reflection coefficient of several reflectarray geometries are presented as function of frequency and of the structural parameters