Range Of Fiber Lengths Research Articles

Performance Analysis of TDFA using 1050nm Pumping Power for 1479nm-1555nm Range

A model of TDFA has been proposed based on simulation after considering all the major parameters like pump and signal power, without considering ASE. Through this analysis of TDFA the optimum value of pump power and the range of fiber length (TDF) have been evaluated. In this section, an effort has further been made to use the least possible fiber length of TDF so as to maximum possible gain and in turn cheaper amplifier. The present research claims to support 96 DWDM channels across 1479nm- 1555nm wavelength range with a channel spacing of 0.8nm. The optimum range of fiber length of TDFA has been evaluated between 8m-16m. The peak gain of ranging from 22 dB to 30.5dB has been attained for selected optimum fiber lengths ranging from 8m to 16m of TDF.

Room temperature single-photon detectors for high bit rate quantum key distribution

We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

CFD simulation of total and regional fiber deposition in human nasal cavities

In this study, CFD simulations of fibrous particle deposition in different realistic human nasal cavities were performed. The airflow field in the cavity was evaluated by solving the Navier–Stokes and continuity equations using commercial software, while a Lagrangian trajectory analysis approach for solving the coupled translational and rotational equations of motion of ellipsoids was developed and used to investigate fiber transport and deposition in the nasal passages. Different breathing rates in the laminar flow regime in the nose and a range of fiber lengths and diameters were used in these simulations. It was shown that the aerodynamic diameter based on the Stokes equivalent diameter is an appropriate parameter for correlating the fiber deposition rate. Presenting the deposition fraction results versus the Stokes-based and pressure-based impaction parameters collapsed the results of different cases for various nose models roughly to a single curve. The simulated regional fiber deposition results were also presented for different nasal cavities. A simple approach developed earlier for modeling non-spherical particles using the shape factor in the drag force was also studied, and the resulting deposition fraction was compared with the present coupled translational–rotational trajectory analysis approach.

Optical Heterodyning for Reduction of Chromatic Dispersion Sensitivity in 60 GHz Mode-Locked Laser Systems

In this paper, a method is proposed to reduce the sensitivity to chromatic dispersion over a fiber optic link based on mode-locked lasers for Millimeter Waves (MMW) generation and transmission. The simulation presented here gives an estimation of the length margin of fiber available for radio-over-fiber networks with minimal sensitivity and maximum received MMW power. The simulation results are verified experimentally by means of a 60 GHz mode-locked laser system combined with an unbalanced Mach Zehnder interferometer for the compensation of the impact of dispersion effects on transmitted MMW power and fiber length range.

Establishing size effects in discontinuous fibre composites using 2D finite element analysis

Size effects are observed within discontinuous fibre composites, such that the material properties change with the specimen volume. Representative volume elements (RVEs) are commonly used to simulate random fibre architectures for finite element analysis of discontinuous fibre composites. A series of simplified 2D RVE models have been created and studied in this paper, in order to determine the relationship between the critical RVE size and fibre length and volume fraction. All models are subjected to periodic boundary conditions, but average properties are extracted from an inner region offset from the model boundary by a distance equivalent to two fibre lengths. According to Saint–Venant’s principle, this offset removes the uncertainty associated with the approximate boundary conditions. A statistical stopping criterion has been adopted to determine the number of realisations required to achieve a representative set of elastic properties for each fibre architecture. The critical RVE side length is shown to be approximately four times the fibre length when considering convergence of the tensile and shear stiffnesses for the range of fibre lengths and volume fractions studied.

Mechanics of SFRC under tension, part II: experimental validation

This is the second of a two-part paper involving a fundamental study of the tensile stress–strain relationship of short-fibre-reinforced concrete under tension. The validation of the analytical model developed in the first part is presented here. The tensile stress–strain results obtained from the theoretical model are compared with the results obtained from the experimental investigations for a wide range of fibre lengths, diameters and volume fractions. The results of the present model are also compared with the tensile stress–strain results obtained from the existing literature. The tensile stress–strain results obtained from the proposed theoretical predictions are found to be in good agreement with the experimental results. The predictability of the analytical approach is also scrutinised for peak load, load at ultimate deformation, ductility and so on. The analytical results show a good conformity, with respect to peak load, toughness and the natures of the ascending as well as descending branches.

Applications of control theory to the dynamics and propagation of cardiac action potentials.

Sudden cardiac arrest is a widespread cause of death in the industrialized world. Most cases of sudden cardiac arrest are due to ventricular fibrillation (VF), a lethal cardiac arrhythmia. Electrophysiological abnormalities such as alternans (a beat-to-beat alternation in action potential duration) and conduction block have been suspected to contribute to the onset of VF. This study focuses on the use of control-systems techniques to analyze and design methods for suppressing these precursor factors. Control-systems tools, specifically controllability analysis and Lyapunov stability methods, were applied to a two-variable Karma model of the action-potential (AP) dynamics of a single cell, to analyze the effectiveness of strategies for suppressing AP abnormalities. State-feedback-integral (SFI) control was then applied to a Purkinje fiber simulated with the Karma model, where only one stimulating electrode was used to affect the system. SFI control converted both discordant alternans and 2:1 conduction block back toward more normal patterns, over a wider range of fiber lengths and pacing intervals compared with a Pyragas-type chaos controller. The advantages conferred by using feedback from multiple locations in the fiber, and using integral (i.e., memory) terms in the controller, are discussed.

An adaptive filter for studying the life cycle of optical rogue waves

We present an adaptive numerical filter for analyzing fiber-length dependent properties of optical rogue waves, which are highly intense and extremely red-shifted solitons that arise during supercontinuum generation in photonic crystal fiber. We use this filter to study a data set of 1000 simulated supercontinuum pulses, produced from 5 ps pump pulses containing random noise. Optical rogue waves arise in different supercontinuum pulses at various positions along the fiber, and exhibit a lifecycle: their intensity peaks over a finite range of fiber length before declining slowly.

Effects of series elasticity and activation conditions on muscle power output and efficiency

The activation of a muscle depends on the function that it is performing and on the architectural properties of that muscle; the two are inextricably linked. Activation conditions such as activation timing, duration and amplitude can be varied throughout a cyclical movement (such as locomotion) and the length change of the whole muscle tendon unit (MTU) can also be varied. Architecturally, muscles have a range of fibre lengths, maximum force-producing capabilities and stiffness of the series elastic element (SEE). In the present work we use a model to explore the relationship between power output and efficiency of a muscle across a range of contraction conditions. We have also examined the mechanical and energetic effects of changing muscle architecture within the model. Our results indicate that whilst there are clear optimal conditions for achieving maximum power output and maximum efficiency, the design of the muscle allows high levels of both to be achieved over a range of activation conditions. This range changes with both SEE compliance and the amplitude of the cyclical length change. The results suggest that a compliant SEE allows a muscle to function closer to the maximum of both power output and efficiency. In addition, by varying the amplitude of the activation level, the efficiency can theoretically remain unchanged, whilst the power output can be modulated.

Fiber characterization for application in heterodyne laser interferometry, part II: modeling and analysis

For beam delivery in a single-fiber-fed heterodyne laser inter- ferometer with nanometer uncertainty, the use of polarization- maintaining (PM) fibers is investigated. The PM properties of the light emerging from the fiber determine the achievable measurement accu- racy. Measurements of the polarization-mixing properties of several dif- ferent PM-fiber types as well as a range of fiber lengths were described in part I of this paper. In this part, a model and analysis of the fiber are presented. By means of the analytical model, a quick selection method is given, which can also be used to precisely align the fiber with respect to the other optical components of the interferometer. The presented model, based on Jones matrices, allows the investigation of local and global disturbances within the fiber and their location. As in part I, the dominant effect of the connector in the fiber assembly is shown. The effects of imperfections in fiber material are shown for longer fibers; they

Generation of fibrous aerosols from thin films

A method of producing relatively monodisperse, small-diameter (sub-500 nm diameter) aerosol fibers is described. This method involves the separation of porous thin films from their substrate. It was found that fibers with diameters of less than several hundred nm and lengths of several micrometers can be formed that do not adhere to one-another. Two μ m thick columnar thin films were fabricated and processed, yielding aerosol fibers with lengths up to 2 μ m and diameters up to 170 nm. Diameter and length distributions of a collected aerosol showed that a broad range of fiber lengths and diameters are formed by this method. Further modification of the method, however, is expected to greatly narrow the range of effective diameters and lengths obtained.

Optimization model of submerged hollow fiber membrane modules

A practical method to obtain optimum design parameters of vertically mounted submerged hollow fiber module was demonstrated to minimize the energy consumption for aeration. Assuming maximum allowable pressure difference in both ends of hollow fiber membrane was 5%, maximum allowable fiber length was calculated for various fluxes and fiber diameters. In case there was no limitation in fiber length, permeate throughput from unit footprint simply increased with fiber diameter. However, if there was a limitation in fiber length/water depth, optimum range of fiber length and lumen diameter existed. For one-side suction, optimum range of outer fiber diameter and fiber length were estimated to be 2.26–3.25 mm and 1.01–1.90 m, respectively, when operating flux was 20–50 l/m 2 h and a ratio of lumen and outer diameter was 1:2. In the case of two-side suction, fiber length of 1.01–1.90 m and diameter of 1.34–2.05 mm were the optimum range. Finally, optimum design lines, showing the best combinations of lumen diameter and fiber length, were obtained for one-side and two-side suctions.

Variants of use of the modified Lindsley-Leont'eva method for chemical fibre spinning products

The mechanical instrument developed by I. S. Leont'eva for assessing the structural properties of products of cotton spinning by the Lindsley method can be used without structural changes with different methods for yarn made of chemical fibres with an average length in the ranges of 32–42, 57–107, and 124 mm. The use of the instrument and its modifications for correctly evaluating the structural products of products of spinning by the Lindsley method for the entire possible range of fibre lengths requires creating a base of the corresponding values of the fractional coefficients. The solution of these problems corresponds to the requirements of the manufacturers and consumers of chemical fibres for the length of staple fibres and the filament stapling length in expanding the yarn assortment.

The Effect of PEEK Fibres and Powder on Joints Made with a High Temperature Adhesive

High temperature adhesives typically exhibit low levels of peel strength since they tend to be more brittle than typical toughened adhesives used for lower temperature applications. It was found that incorporating thermoplastic fibres or powder into the bondline of a joint made with a high temperature epoxy-based adhesive resulted in significant improvements in peel strength. Poly(ether ether ketone) (PEEK) fibres and powder were incorporated into the adhesive resin and used in aluminium joints. These were tested in peel and single lap shear using a range of fibre lengths, orientations and volume fractions. It was seen that large increases in peel strength could be achieved but that lap shear strength was degraded with most types of modification. However, some modifications resulted in significant increases in peel strength with limited decrease in lap shear strength. These improved properties have been achieved using physical modifications rather than chemical alteration of the resin.

The Importance of Thin Layer Chromatography in the Analysis of Reactive Dyes Released from Wool Fibers

Abstract Samples of reactively-dyed wool were obtained from a range of manufacturers and distributors and “digested” by alkaline hydrolysis to yield colored solutions. Results demonstrate that thin layer chromatographic analysis of reactive dyes yields important additional information, over and above that obtained from techniques such as comparison microscopy and visible light microspectrophotometry. Colored solutions obtained from single fibers were analyzed by thin layer chromatography (TLC) and reproducible results were obtained from a range of fiber lengths.

Relationship Between Cotton Fiber Strength and Cellulose Molecular Weight Distribution: HVI Calibration Standards

High volume instrument (HVI) classing of the U.S. cotton crop has focused attention on fiber quality, particularly strength. Characteristic of polymers is the relationship between molecular weight and physical properties. Cotton fibers composed mostly of the polymer cellulose were dissolved in the solvent N,N-dimethylacetamide with lith ium chloride without cleanup or derivatization. Molecular weight distributions were determined by automated, nonaqueous gel permeation chromatography; HVI calibra tion standard cottons possessing a range of fiber lengths and strengths were sampled. Molecular compositional profiles indicate correlation of higher average molecular weight with greater strength of cotton fibers.

Fiber characterization in a stationary ultrasonic field

An instrument has been developed to characterize the mean dimensions of softwood fiber samples. It is based on the phenomenon that particles of cylindrical shape diluted in water and shorter than one fourth of the acoustic wavelength migrate to nodal planes of acoustic radiation pressure and reorient parallel to these planes when subjected to a stationary ultrasonic field. As the resonator operating frequency is 72 kHz, fibers up to 5 mm in length can be measured. The time evolution of the fiber suspension during ultrasonic excitation is monitored with a collimated beam of light. Scattered light signals collected off-axis in the plane perpendicular to the acoustic nodal planes are shown to be a function of the weighted average fiber length. Results are presented for pulp samples in the average fiber length range of 0.2 to 3 mm. It was found that there is a region where the scattered light is linearly related to concentration. Acoustooptical measurements obtained at initial concentration in this linear region, for all fractions, have shown that the longer the average length from screen classifier is, the faster the layer formation is. Since the fiber length the radius are proportional for a wood species, this observation is in agreement with the theoretical prediction.

MODULATION INSTABILITY IN NONLINEAR MONOMODE OPTICAL FIBERS

Modulation instability in nonlinear monomode optical fibers is studied in letail. The condition of producing modulation instability and the maximum modulational growth rate as well as other formulas about modulation instability are presented. We obtain the conclusion that modulation instability can be produced not only in the region of anormalous dispersion but also in the region of normal dispersion. We determined the appropriate range of fiber length for maintaining the modulational growth.

Dynamic properties of aligned short carbon fibre-reinforced plastics in flexure and torsion

Theoretical and experimental studies of the dynamic material properties of short aligned carbon fibre-reinforced plastics are described. It is shown that, by correct choice of fibre aspect ratio and volume fraction, the damping of composites can be improved whilst retaining high modulus of elasticity. Both flexural and shear properties have been studied and experimental techniques for dynamic measurements are described. It is shown how material loss factors may be deduced from specimen loss factors and results are presented for a range of fibre lengths from 0.25 to 3.0 mm. Moulding techniques for manufacturing short aligned fibre-reinforced plastic rods and beams to a required fibre distribution and alignment have been developed.

An Examination of the Digital Fibrograph Length Uniformity Index1

The Digital Fibrograph length uniformity index is usually misinterpreted. The theoretical maximum for this index is 51.28. The theoretical maximum index requires that: 1) all cotton (Gossypium sp.) fibers within the beard being scanned by the Fibrograph have the same length, 2) that the fibers are randomly caught and held, and 3) that the optical scan of the beard begin at the point of holding. The latter condition does not exist, because the scan of the beard begins at 3.81 mm from the point of holding. The result is that maximum possible uniformity index is increased to 56.0 for 40 mm and to 60.7 for 20 mm fibers. Direct comparisons of the uniformity index are valid only in a narrow range of fiber lengths.