Em (ii) temos uma configuração de MZI que divide o sinal óptico entre o núcleo e a casca da fibra por meio de emenda entre duas fibras com um minúsculo desalinhamento (offset) lateral. Devido a esse offset, parte do modo do núcleo é acoplada a diversos modos da casca, sem sofrer forte influência do comprimento de onda. Essa configuração supera em custo e rapidez o método que utiliza um par de LPGs. A quantidade de modos da casca e a perda de inserção podem ser controladas por meio de ajuste da quantidade de offset . Constituindo outra forma de se ter um MZI em linha, (iii) apresenta configuração baseada na emenda entre uma fibra SMF e duas fibras de cristal fotônico (PCF-Photoniccrystalfiber). É de fácil construção e não necessita de nenhum processo complicado de alinhamento ou clivagem. O modo do núcleo em uma PCF é expandido para a região de lacuna de ar colapsada, tal que parte dele pode ser acoplado aos modos da casca da PCF. No entanto, tem-se acoplamento para diversos modos da casca, o que dificulta o controle do número de modos envolvidos, além de apresentar maior perda de inserção em comparação ao método anterior .
The Full-Vectorial Finite element method (FV-FEM) is advantageous in complex geometries of photoniccrystalfiber. It is a full vector implementation for both propagation and leaky modes and cavity modes for two dimensional Cartesian cross sections in cylindrical co- ordinates. First and second order interpolant basis are provided for each triangular elements. PML (Perfectly matched layer) boundary conditions is employed at computational domain for evaluating effective mode area and birefringence of the proposed PCF .We begin with the source-free time harmonic form of the vector wave equation in an arbitrary, anisotropic lossy media .
Abstract — In this paper we have presented the four new investigations using different structures of PhotonicCrystalFiber (PCF) for broadband communication applications and narrows down on the design which can provide largest flat negative dispersion. The new structure model is optimized based on the combination of modal properties and dispersion compensation. The results were recorded over a transmission frequency range from 190.95 THz to 245.73 THz i.e. 1.22 µm to 1.57 µm with a dispersion -704.62 ps/nm/km. The results obtained from the new different PCF structures are compared with reported results for different 2D PCF models so far.
Abstract— Fiber-To-The-Home (FTTH) technology has been significantly implemented in access networks, providing very high data rates transmission and a variety of digital content to subscribers. It involves an optical cable link being installed between the building entry point and each subscriber with the Multiple Dwelling Units (MDUs), i.e. flats and apartments. In other words, optical cable has to lie fairly straight to carry a strong signal, since typically is necessary to bend, twist and turn the lines in and out of tight corners without degrading the link connection. In this paper we propose the use of Hollow-Core PhotonicCrystalFiber (HC- PCF) for FTTH applications. It is presented an experimental analysis of the macrobending effects in a HC-PCF based on a comparison with traditional fibers and by following the ITU-T G.657B standard recommendations. We observe this fiber, with only 6.5 m core, is bending loss insensitive, even at extremely small bending radius of 2 mm, in which it presents a loss of only 0.58 dB.
(DTA) by using NETZSCH STA 409 CCD from 25°C to 600°C as heating rate of 20 °C/min in a nitrogen atmosphere. Figure 5 illustrates the changes in TG and DTA curve of GLP crystal. The DTA curve implies that the crystal undergoes an endothermic transition of two significant peaks at 154°C and 337 °C, where the material begins to melt. The first peak of endothermic represents the temperature at which the melting terminates which corresponds to its melting point. The TG curve of this crystal indicates that the material is stable upto to 341°C and above this temperature the weight loss is not due to self degradation of GlP but merely its evaporation after its melting. The sharpness of the endothermic peak shows good degree of crystallinity of the grown crystal and thermodynamically stable in all atmospheres at room temperature.
The mechanical failure behavior of individual reinforcing fibers is an important performance aspect of fiber reinforced composite systems. This is particularly true of ceramic matrix fiber composites in which the majority of the work of failure occurs during fiber failure and pullout in the post-matrix cracking and post-ultimate strength region. This dissertation seeks to understand the statistical behavior of fiber failure in brittle matrix composites and to develop methods for determining the onset of fiber failure as a signal for the onset of irreversible failure of the reinforcing structure. Fiber failure in aligned fiber bundles, both free and in model composites, was tested under tensile loading to determine the onset of fiber failure and the statistical distribution of fiber failures by direct interrogation of the continuity of model fibers. Fiber interrogation monitored in real time the electrical continuity of aluminum metal coated glass fibers. A model composite consisting of the aluminum-coated glass fiber in an epoxy resin matrix was studied to determine the failure behavior of individual fibers in a composite environment. Glass fibers in an epoxy matrix was selected as a composite model due to the high E f /E m , high σ f /σ m and nearly brittle behavior of the epoxy matrix selected. An electronic high speed analog/digital interface was used to monitor the electrical, and hence mechanical, continuity of the fibers under test. These data were used to assess the onset of the individual fibers failure, the calculation of apparent fiber strengths, and the determination of Weibull distribution of the apparent fiber strength values. The procedure developed in this work for assessing fiber failure in bundles and composites has been shown to be sufficiently sensitive to resolve the onset of fiber failure in bundles and in model composites prior to measurable reductions in load carrying capacity, thus providing a means for early detection of fiber failure. The procedure is also a means by which the failure mode of fibers in composites can be compared to classical bundle theory failure,thus supporting or refuting a popular model.
Biostimulants are used in cotton (Gossypium hirsutum L.) to balance vegetative and reproductive growth as well as to increase cotton seed yield and fiber quality. Therefore, in order to study the efficiency of seed treatment with biostimulants, nutrition, production and technological quality for the cotton fiber, a field experiment was installed. The study was conducted at the Alvorada farm research field, in Luis Eduardo Magalhães municipality - BA. The experiment was arranged in a completely randomized block design with four replicates and five treatments (control group, untreated group, Booster®, Stimulate®, Improver® and Biozyme®). Leaf contents of nutrients, yield and technological quality of the fiber were evaluated. The results showed that application of biostimulants in the seeds increased the N, K, S and Fe contents in the cotton leaf, but there was no influence on the crop yield. However, these products caused changes in the fiber characteristics, related to length uniformity, micronaire, length and strength of the fiber.
this type occurs below rafts up to a paleo-water level mark characterized by a shelfs- tone mark 10 cm above the present-day water level. There is no field or petrographic evidence, however, suggesting that fluctuating paleo-water levels in the cave represent controlling factors for formation of crystal accumulations and other modes of forma- tion are consequently discussed. Perhaps the main lines of evidence comes from
formers was found to be densely populated. Lattice energy minimisation of the lowest energy structures was performed incorporating the distributed multipole charges. The unique optimized crystal structures were refined and studied thoroughly. The stability of the selected structures was verified by analyzing the intermolecular interactions and second derivative mechanical properties, con- firming that the structures had achieved the Born criteria of stability. Detailed analysis of the hydrogen bonds showed that Str8, Str20 and Str99 had similar interactions to the δ, α and β polymorphs of pyrazinamide indicating their physic- ally favourable nature. The Hirshfeld 2D fingerprint plot analysis of the predicted polymorphs revealed that the majority of the interactions are made by the amide and carboxylic group of the molecule, providing a major contribution to the Hirshfeld surface, thereby achieving the stability. The favourable results from the studies made for the theoretical crystal structures of pyrazinamide justify the sel- ected flexible torsion angle and the potential field used for the current prediction methodology. The similarities of the optimized structures with respect to the experimental known polymorphs of pyrazinamide proved the authenticity of the generated energy landscape. Thus the lower energy optimized theoretical struc- tures of pyrazinamide generated via the current prediction method in the energy landscape could be considered as potential polymorphs of pyrazinamide, which are resolved or yet to be resolved, thereby the current methodology was validated.
Table 1 provides a summary of the analysis of variance of cell element size in Eucalyptus grandis wood at age 21 years, as a function of each factor. It was noted that, as regards the fertilization factor, only vessel frequency was significantly influenced. As for log position along tree height axis, significant differences were observed only for vessel element length. As for radial position, significant differences occurred for: fiber length, fiber diameter, fiber wall thickness, vessel element length, vessel diameter and vessel frequency.
Crude fiber does not represent a homogeneous group of substances, as it is composed mainly of nonstarch polysaccharides (NSP) (Goñi et al., 2009). The NSP fraction can be classified as insoluble (cellulose and hemicellulose) and soluble (pectins, gums, and mucilages), according to its solubility in water. The soluble NSP is digestible during the passage through the digestive tract (Amirkolaie et al., 2005; Krogdahl et al., 2005). In the present study, the ADC of the NSP fraction was not determined. However, according to the coefficients provided by the CF as an indicator of digestibility, it is possible that NSP fraction has not undergone degradation. Determination of the CF by the Weende ’ s method may have affected the obtained coefficients because, in the Weende ’ s method, parts of the hemicellulose and the lignin are solubilized and become part of the nitrogen-free extract (Silva & Queiroz, 2006).
samples were ground in a Wiley mill with 1 mm sieve, and stored in polyethylene containers for further analysis. Samples were analyzed for the contents of dry matter at 105°C according to AOAC (1980), ether extract and ash according to AOAC (1995), crude protein by determining the nitrogen content by the Kjeldahl method, according to AOAC (1980); neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen, according to Silva and Queiroz (2002), neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose and lignin by the sequential method of Van Soest et al. (1991), non-fiber carbohydrates by the formula NFC = 100 - (CP + EE + ash + NDF) and total carbohydrate by the formula TC = 100 - (CP + EE + ash), according to Sniffen et al. (1992).
Konca et al. (2005) for normal maize silage. The ether extract, crude fiber, hemicellulose, ADF and NDF values of treatment groups were not different from each other (p > 0.05) (Table 1). Gurbuz and Kaplan (2008) reported similar ADF and NDF ratios for pure maize silage. Mohammadzadeh, Khorvash, and Ghorbani (2014) reported that DM, NDF, CP and WSC ratios were not influenced from frosting. In contrast, frosting increased yeast population on crop. Narasimhalu et al. (1986) reported that detergent fiber ratios were higher in the post-frost than pre-frost silages. Although ADF and NDF contents did not exhibited any significant differences between treatment groups, higher ADF values were observed in LEN group. In contrast, higher NDF values were observed in control group. Increases in fiber concentration can be explained by differences in the amount of DM losses that happen during the fermentation process. The enzyme supplementation to silage had been practiced as a method to degrade cell walls and subsequently improve the digestibility of silage fiber (McDonald, 1981). The higher fiber values may be achieved through combined effect of lower DM recovery and reduced hydrolysis of hemicellulose in frosted silages treated with LAB or enzyme groups (Basso et al., 2012). However, it was not expected that LAB or LEN treatment decreased NDF contents (Guan, Driehuis, & Wikselaar, 2003).
this work is to study ramie fiber as composite reinforcement, with the concern to, in the future, maintain the culture of the fiber in the country. Also, to attend the urgent need to develop environment-friendly materials, this study focused on to improve the fiber-matrix interaction without chemical treatments (washed ramie fiber) and to prepare the composites by the resin transfer molding (RTM) technique. RTM is used in the automobilist industry and have some advantages against conventional techniques, e.g. low capital investment, void content reduction, low cycle times, better process control with consequently waste reduction 6 .
(Received 26 April 2011; revised manuscript received 28 August 2011; published 21 September 2011) A comprehensive study of the properties of light propagation through one-dimensional photonic disordered quasiperiodic superlattices, composed of alternating layers with random thicknesses of air and a dispersive metamaterial, is theoretically performed. The superlattices consist of the successive stacking of N quasiperiodic Fibonacci or Thue-Morse heterostructures. The width of the slabs in the photonic superlattice may randomly fluctuate around its mean value, which introduces a structural disorder into the system. It is assumed that the left-handed layers have a Drude-type dispersive response for both the dielectric permittivity and magnetic permeability, and Maxwell’s equations are solved for oblique incidence by using the transfer-matrix formalism. The influence of both quasiperiodicity and structural disorder on the localization length and Brewster anomalies are thoroughly discussed.
The propagation of electromagnetic waves in periodic stratified structures formed by chiral media and Tellegen or ferrite materials was studied. In case of Tellegen photonic crystals, it was proven that in general the eigenmodes are not degenerate for propagation along the stratification direction, except if the structure exhibits a two-fold rotation symmetry (about the y-axis) or, alternatively, if all the involved media are in the same equivalence class. Surprisingly, we discovered that notwithstanding the nonreciprocal response of Tellegen media, the photonic band diagrams are always spectrally symmetric. We explained this result by showing that the spectral symmetry is protected by a symmetry transformation that corresponds to the time-reversal operation followed by the y-inversion operation.
We have analyzed the performance of a simple two 34 tap cascaded incoherent spectrum sliced transversal microwave photonic filter. Our proposed filter is composed of cascading two incoherent fiber Fabry Perot filters with different FSRs. We have considered three cases of filter configuration in terms of its incremental differential delay. The simulated results shows that the performance of this cascaded filter combination can be tuned over the frequency range from 4.6 GHz to 18 GHz with very good sidelobe suppression level. This was achieved by cascading two Fiber FP filters and by carefully choosing individual filters FSR. The future scope of this paper is by employing windowing technique to reconfigure the overall filter transfer function.
Self-cleaned Solar Cells with Super-Hydrophobic Photonic Nano-structures xx Figure 3.5.3 – (a) Static and dynamic contact angles of Parylene with different O2 plasma treatment times and 1min SF6 using a 1.6 μm PS sphere mask and (b) respective droplets’ profiles. ................................................................................................................................ 22 Figure 3.6.1 – Graphical representation of parameters to be included in the models. In this example, and . .............................................................................................. 24 Figure 3.6.2 – Contact angle gain (%) due to surface chemistry modification with different RIE time. ............................................................................................................................. 25 Figure 3.7.1 – Total (solid lines) and diffuse (dashed lines) transmittance of (a) PET and (b) parylene. (SF6 50sccm, 50W) ............................................................................................... 26 Figure 3.7.2 – Total (solid lines) and diffuse (dashed lines) reflectance of (a) PET and (b) parylene with varying SF6 plasma treatment time. (SF6 50sccm, 50W) ............................... 26 Figure 3.7.3 – Haze in transmittance (equation 1.4) spectra of (a) PET and (b) parylene surfaces with varying SF6 plasma treatment time. (SF6 50sccm, 50W) ................................ 27 Figure 3.7.4 – Absorbance spectra of (a) PET and (b) parylene surfaces with varying SF6 plasma treatment time. (SF6 50sccm, 50W) ......................................................................... 27 Figure 3.8.1 – Comparison between measured I-V curves of a solar cell without any coating (reference), with a flat 5 μm parylene coating (smooth) and after structuring the parylene (textured). The inset shows an amplified view of the I-V curves between 0V and 0.7V. ....... 29 Figure 3.8.2 – and efficiency enhancement of textured parylene coated cells relative to flat ones. .............................................................................................................................. 29 Figure 3.8.3 – Comparison between EQE measurements (Left) of a-Si n-i-p solar cells with the same coating as those of Figure 3.8.1. (Right) ................................................................ 30 Figure 3.8.4 – enhancement of the studied batch of cells with a substrate (n-i-p)