Effects Of Fiber Dispersion Research Articles

A multiscale thermo-mechanical coupling model for Fiber-Reinforced Cementitious Composite (FRCC)

This paper aims to develop a multiscale thermo-mechanical coupling model across from meso-scale to macro-scale to study the tensile thermos-mechanical behavior of fiber-reinforced cementitious composite (FRCC) on the base of thermodynamics. In meso-scale, the coupling process of thermal effect and the development law of a single crack were creatively presented and formulated in energy potential function. The effects of fiber dispersion on cracking behavior and crack strength of matrix were determined. In macro-scale, the multiple-fine-cracks and strain-hardening/softening behavior under tension were defined and studied. The bridging action stress of fibers is calculated by considering the bonding stress in the interface transition zone (ITZ). The model can be upgraded for FRCC materials ranges from strain-hardening cementitious composite (SHCC) and engineered cementitious composite (ECC). The numerical calculations of the proposed model were conducted based on the Fortran program for validation. The residual tensile strength, multiple-fine-cracks and strain-hardening/softening behaviors of FRCC were predicted. The behaviors of FRCC with different fiber types were accurately captured in a range of temperature from 20°C to 600°C through the comparative study with six groups test results in literatures. A sensibility study was carried out to analyze the impact of modelling parameters and thermal effect on the strain-hardening/softening behaviors of FRCC.

Four wave mixing, average amplified spontaneous emission, and channel spacing effects on the optical transceiver systems based on multi pumped Raman amplifiers

Abstract This study has clarified the four-wave mixing, average amplified spontaneous emission, and channel spacing effects on the optical transceiver systems based on multipumped Raman amplifiers. The employed spectral width is applied in the fiber core from 1450 nm to 1650 nm through the subgroups in the fiber link. The optical loss and fiber dispersion effects are demonstrated with the spectral wavelength band with different pumping levels. The optical loss is clarified in relation to different laser pumping levels and different number of links per fiber core channel at 1550 nm. As well as the dispersion factor is demonstrated in relation to different laser pumping levels and different number of links per fiber core channel at 1300 nm. Extended fiber length, amplifier gain, and repeater spacing are clarified with different laser pumping levels and different number of links variations per fiber core channel at 1550 nm. The data rate transmission is studied against different laser pumping levels and different number of links variations per fiber core channel at both 1550 nm and 1300 nm. The optimum fiber coupled power is demonstrated against different laser pumping levels and different number of links variations per fiber core channel at 1550 nm. The fiber coupling efficiency is studied and demonstrated against different laser pumping levels and different number of links variations per fiber core channel at 1550 nm.

All-optical, filter-free, image-reject, and fundamental/sub-harmonic downconverted RoF link

An all-optical, image-reject, and fundamental/sub-harmonic downconverted radio-over-fiber (RoF) link using a polarization-division multiplexing Mach–Zehnder modulator (PDM-MZM) and fiber-dispersion effect is proposed. At the remote antenna unit, the receiving radio frequency (RF) signal and the local oscillator (LO) signal are used to drive two sub-MZMs of the PDM-MZM. After a length of optical fiber transmission, at the central office, by using the fiber-dispersion effect and controlling the polarization controller to introduce an appropriate phase shift between the RF and LO sidebands, image rejection is achieved and power fading is avoided simultaneously. Because the scheme is a simple and all-optical system without electrical frequency-dependent devices or filters, it has a good image-reject capability over a large working frequency range. Besides, the downconverter in sub-harmonic mode can decrease frequency requirement of the LO signal. Experimental results indicate that in the fundamental and sub-harmonic downconverters, for a single-tone signal, IRRs are over 47 dB. Image rejection for the 100-Mbaud 16-QAM signal and demodulated desired IF signal with a good EVM of less than 7% are realized. The proposed structure can be applied in RoF systems and microwave and millimeter-wave receivers.

An Overview on the Dispersion of Steel Fiber in Ultra-High-Performance Concrete

Abstract Ultra-high-performance concrete (UHPC) is widely recognized for its high toughness, which is directly affected by the dispersion of steel fiber and its loading mode. To investigate the reinforcement effect of steel fiber, this paper summarizes the influencing factors, evaluation methods, and theoretical models of steel fiber dispersion in UHPC. First, the results reveal that a scientifically designed mixture can reduce the cost of steel fiber dosage in UHPC and improve fiber dispersion by adjusting matrix rheological properties. The optimum plastic viscosity of the slurry should range from 30 to 80 Pa·s for achieving the best fiber dispersion effect. Second, during slurry placement, the orientation of fibers in UHPC can be improved by up to 80 % through flow induction and the wall effect, which increases the bending strength, tensile strength, and toughness of UHPC matrix by 5–67 %, 30–90 %, and 13–200 %, respectively. Moreover, although the dispersion of fiber in two-dimensional space has been extensively studied, further characterization in three-dimensional space is required. Lastly, some theoretical simulation results have been achieved on fiber orientation, but factors such as aggregate or reinforcement must be considered.

Dissipative light bullets in a doped and weakly nonlocal optical fiber

The letter introduces an extended (3+1)-dimensional [(3+1)D] nonlocal cubic complex Ginzburg-Landau equation describing the dynamics of dissipative light bullets in optical fiber amplifiers under the interplay between dopants and a spatially nonlocal nonlinear response. The model equation includes the effects of fiber dispersion, linear gain, nonlinear loss, fiber nonlinearity, atomic detuning, linear and nonlinear diffractive transverse effects, and nonlocal nonlinear response. A system of coupled ordinary differential equations for the amplitude, temporal, and spatial pulse widths and position of the pulse maximum, unequal wavefront curvatures, chirp parameters, and phase shift is derived using the variational technique. A stability criterion is established, where a domain of dissipative parameters for stable steady-state solutions is found. Direct integration of the proposed nonlocal evolution equation is performed, which allows us to investigate the evolution of the Gaussian beam along a doped nonlocal optical fiber, showing stable self-organized dissipative spatiotemporal light bullets.

Generation of optical UWB signals based on combined bright solitons

We investigate the generation of ultra-wide band (UWB) signal in all optical domain based on combined bright solitons by numerical method. The combined solitons with ultra-wideband characteristics can be obtained by multiple bright solitons. The power spectrum can be modulated by pulse interval, pulse width and phase difference of combined bright solitons to satisfy with the Federal Communications Commission (FCC) spectrum mask. Meanwhile, the transmissions of combined bright solitons in single-mode fibers are discussed. The fiber loss and dispersion effects have the influence on the transmissions of combined bright solitons. In order to eliminate dispersion effects, the stable transmission of signals in dispersion decreasing fibers is proposed.

Effect of Some Parameters on Optical Soliton Pulses in Photonic Crystal Fibers

Fiber optics have been greatly enhanced by photonic crystal fibers based on microstructured air-glass designs. On the one hand, such fibers enable very tight light confines in a small mode shape region, resulting in significantly improved alternative options between light and dielectric medium. Photonic crystal fibers, on the other hand, allow light to be guided via air core instead of glass. As a result, the latter form of fiber decreases optical nonlinearities in ways that classic fiber designs cannot. The chirp effect and dispersion of photonic crystal fibers with super-Gaussian pulses during various pulses durations are examined in this paper in both normal and anomalous dispersion patterns. The chirp effect and fiber dispersive nonlinear effects are investigated. For this study, a mathematical model of the solution of a nonlinear equation involved the split-step Fourier method. Peak power was reduced for broad pulses. When the magnitude of the super-Gaussian pulse increased proportionally, pulse constriction was also noticeable, Furthermore, the results reveal that an anomalous dispersion system was superior to a regular dispersion system for pulse . The experimental findings will facilitate further research into more understanding of photonic crystal fibers, and to improve data speeds in modern optical communication systems

800G/$\lambda $ Self-Homodyne Coherent Links With Simplified DSP for Next-Generation Intra-Data Centers

Assuming a low-latency forward error correction (FEC)-based bit-error-rate (BER) threshold, we demonstrate and provide a detailed analysis of a 120 Gbaud/DP-16QAM single-carrier self-homodyne coherent link in the C-band. Through theoretical and simulation analysis as well as experimental investigation, we find that a minimum receiver DSP based on a simple I-Q correction scheme is needed to compensate for the combined effect of fiber dispersion, I-Q phase rotation, transmitter I-Q impairment, and receiver skew in combination with a finite analog to digital converter (ADC) resolution. Based on the simplified DSP, we demonstrate link budgets of 4.5 dB (for 16 amplified dense wavelength division multiplexing (DWDM) channels) and 5.2 dB (unamplified single-channel case). The amplified DWDM self-homodyne coherent system provides a 12.8 Tb/s capacity per fiber pair and is useful for bandwidth-demanding intra-data center applications.

Sustainable Cement Composite Integrating Waste Cellulose Fibre: A Comprehensive Review.

This review presents the research conducted to date in the field of cement-based composites reinforced with waste paper-based cellulose fibres, focusing on their composition, mechanical properties, and durability characteristics. The literature demonstrates that the properties of raw material (depending on their own chemical composition) significantly influence the formation of the cement composite binders. When considering fresh properties, the presence of silica and magnesium compounds generally lead to favourable effects on the setting of the cement composite when combined with waste paper cellulose fibre. Reduction in density values, i.e., approximately 25%, was observed with the inclusion of waste paper fibres from 20 to 80% in cement composites. The homogeneous dispersion of fibres in the matrix is one of the crucial factors to achieve in order to develop composites with well-balanced mechanical properties incorporating waste paper cellulose fibres. Hence, dispersion of fibres can be improved by increasing water quantity corresponding to the optimal value, which was a water/cement ratio of 0.64 leading to optimum strength properties of the composite. Even though the effect of fibre dispersion in the matrix improves with the addition of water, higher porosity and voids govern the strength properties beyond an optimum water-to-cement ratio. Higher porosity leads to an increase in the water absorption and a lowering of the thermal conductivity properties with the addition of paper fibre in cement binders. Paper fibre absorbs a high amount of water leading to higher water absorption. This phenomenon is related to the hydrophilic nature of cellulosic fibres absorbing some volume of water due to their microporous structure.

Switchable property of dissipative soliton and dispersion-management soliton in fiber laser

We numerically and experimentally demonstrated that the central wavelength of the output pulses in an Er-doped mode-locked fiber laser can be switched from ∼1561 to ∼1531 nm, while these two pulses exhibit dispersion-management soliton and dissipative soliton, respectively. The switch capability of our fiber laser with different pulse waveforms can be attributed to combining the double-hump gain spectrum of Er-doped fiber and third-order dispersion (TOD) effect. By considering the TOD effect, the two wavelengths can be operated in different dispersion regime. The transient switch dynamics of these different type of solitons are also observed by time stretched technique. These findings provide a good foundation for comprehensively studying pulse formation dynamics in laser cavities, and benefit for design dual-wavelength fiber lasers.

A review of existing codes and standards on design factors for UHPC placement and fiber orientation

• Review different construction procedure and their effects on fiber orientation. • Review existing UHPC design codes and their consideration of fiber orientation. • Recommendation on following UHPC design codes regarding fiber orientation. • Identify future research on construction procedure to ensure fiber orientation. Ultra-high-performance concrete (UHPC) has been extensively researched and implemented in various infrastructure applications for its superior structural and durability performance. Despite their successful structural level demonstrations, fiber dispersion and orientation remain a concern in the UHPC structure design. The casting flow direction, formwork geometry, rebar arrangement, use of casting device, and rheology of the mixtures are all reported to affect the fiber orientation and ultimately the structural performance of the UHPC members. A number of UHPC design codes and guidelines have been published by professional organizations across different countries, and the effect of fiber orientation were considered in several distinct ways in these specifications. In this article, a comprehensive review was conducted on the influence of various factors on the fiber orientation in structural elements. Existing structural design guidelines on UHPC, and steel fiber reinforced concrete materials from France, Germany, Japan, South Korea, Canada, Switzerland, Australia, and the U.S. were reviewed with a focus on their respective methods to account for the effect of fiber dispersion and orientation. Several design codes introduced separate design reduction factors to compensate the effect of undesirable fiber orientation. The background work and underlying rationale of these design factors were also included in this paper. Recommendations to the design professionals and for future research directions were provided at the end of the paper.

Theoretical Analysis of The Super-Gaussian Pulse Propagation in Solid-Core Photonic Crystal Fiber

Fiber optics have been greatly enhanced by photonic crystal fibers based on microstructure air-glass designs. On the one hand, such fibers enable highly tight light confine in a small mode shape region, resulting in significantly improved alternative options between light and dielectric medium. Photonic crystal fibers, on the other hand, allow light to be guided via air cores instead of glass. As a result, the latter form of fiber decreases of optical nonlinearities in ways that classic fiber designs cannot. The chirp effect and dispersion of photonic crystal fibers with super-Gaussian pulses during various pulses durations are examined in this paper. In both normal and anomalous dispersion patterns. As done the chirp effect and fiber dispersive nonlinear effects are investigated. For this study, the mathematical model of the solution of nonlinear equation is split-step Fourier method. The peak power reduces for broad pulses. When the magnitude of the super-Gaussian pulse increasing proportion, the pulse constriction is also noticeable, Furthermore, these results disclose important facts, such as the fact that an anomalous dispersion system is superior to a regular dispersion system for pulse. These findings are incredibly useful in learning more about photonic crystal fiber and improving data speeds in modern optical communication systems.

Some Effects of Fiber Dispersion on the Mechanical Response of Incompressible Soft Solids

Some Effects of Fiber Dispersion on the Mechanical Response of Incompressible Soft Solids

Mechanics of deformation and failure of hybrid polymer composites

High performance composites can be designed, and their properties tailored to enhance specific mechanical (or multifunctional) properties of the material. Fibre hybridization, which consists of combining multiple types of fibres in the same composite material, is a strategy that can lead to improved composite properties and performance, as it not only changes the material properties but also  the damage propagation mechanisms leading to final failure. In this work, two numerical frameworks are proposed to analyse the mechanics of failure of hybrid polymer composites. Firstly, a FEM framework is used to analyse the mechanisms that lead to longitudinal failure of composite materials. The effects of superimposed hydrostatic pressure on longitudinal tensile failure is analysed and a generalized reduction in strength with increasing pressure is predicted. Secondly, a dynamic Spring Element Model is proposed and used to analyse the dynamics of the formation of clusters of broken fibres and the effects of fibre dispersion in hybrid composites, concluding that higher fibre dispersion leads to improved material performance. Additionally, an experimental campaign on two different hybrid materials (inter and intratow) is performed to understand the effect of hybridization on fibre dominated properties, namely longitudinal tensile strength and translaminar fracture toughness. The interply hybrid material is obtained by stacking alternating T800 and HR40 thin-ply layers, while the intratow is obtained by combining the two types of fibres in the same layer using spread tow technology. A change in the damage mechanisms through hybridization is observed, which can lead to improved material performance.

Performance analysis of an optical TDM transmission link considering fiber dispersion and demultiplexer crosstalk

This paper outlines the performance evaluation of high speed optical time division multiplexed (OTDM) system considering the effect of fiber dispersion and the impairments of nonlinear optical loop mirror (NOLM) used as a demultiplexer. The system performance gets deteriorated by the channel crosstalk and the relative intensity noise (RIN) of the NOLM. Our investigation demonstrates that the system is penalized in terms of power penalty significantly when the intrinsic crosstalk becomes higher than −25 dB. The power coupling ratio must be within the range of 0.47–0.53 in order to maintain the intrinsic crosstalk within −25 dB level. Our analysis also indicates that the system suffers more power penalty with the increasing number of demultiplexing channel and the amount of pulse walk-off between signal and control pulse. Apart from channel crosstalk the system performance is also investigated taking into account the effect of intensity fluctuation of the demultiplexed signal which is called RIN of the NOLM. The system suffers from significant power penalty for the value of such noise higher than 10−5. It is also reported that the power penalty is significant when the chromatic dispersion index becomes higher than 0.30.

On the 40 GHz Remote Versus Local Photonic Generation for DML-Based C-RAN Optical Fronthaul

Local and remote photonic millimeter wave (mmW) signal generation schemes are theoretically and experimentally evaluated in order to compare both approaches for practical deployment in a cloud radio access network (C-RAN) fronthaul network. The paper presents a full comprehensive formulation of the frequency response of a system based on a directly modulated laser transmitting data over 40 GHz signal which is generated by external carrier suppressed modulation and optical frequency multiplication. Theoretical and experimental characterization of the system response at baseband and mmW band for local and remote generation setups show very good agreement. The remote configuration leads to a higher electrical output power (i.e., 15 dB higher in 25 km fiber links) than the local generation setup in the mmW band due to the combined effect of chirp and fiber dispersion, although intermodulation distortion is higher in the former case. Transmission experiments using quadrature phase-shift keying (QPSK) signals with 250 MHz bandwidth centered at 0.5 GHz over 10 and 25 km fiber links also confirm the superior performance of the remote setup, whereas the local setup leads to similar results to optical back-to-back (OB2B) measurements, which is also validated with data signals centered at different frequencies within the laser bandwidth frequency range. Finally, experimental results show the quality of the recovered signals in terms of error vector magnitude (EVM) as a function of the received electrical power and demonstrate that no further penalties are introduced by photonic mmW signal generation with respect to electrical back-to-back (EB2B) levels.

Nonlinear Effect and MAI Impact on SAC-OCDMA System Based on 2D Multi-Diagonal Code and Laser Array

A new architecture for Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) system based on two Dimensional Multi Diagonal (2D-MD) codes named 2D-MD SAC-OCDMA and utilizing a laser optical source is proposed for Long-Reach Passive Optical Network (LR-PON). In this work, a computer simulator tool is used, for the first time, as a SAC-OCDMA simulation set-up utilizing the unique combination of a coherent laser array and 2D-MD codes. In addition, the system performance is addressed numerically by taking into account Multiple Access Interference (MAI), optical coherent source noise, first, second and third order fiber dispersion, nonlinear effects and photo-detector noise. Simulation results indicate that for a single user (i.e., without considering MAI), the system can operate at a maximum bit rate of 55 Gb/s over 250 km of Single Mode Fiber (SMF), with a Bit Error Rate (BER) below 10−9 (Q-limit = 15.5 dB), when only first order fiber dispersion is considered. However, including the effects of second and third order fiber dispersion as frequency domain parameters, results in a reduction of the maximum bit rate to 40 Gb/s, while maintaining a Q-factor above the Q-limit under the same transmission distance. Furthermore, we demonstrate that the proposed architecture extends the SMF transmission reach up to 600 km and 480 km, when considering linear and nonlinear effects, respectively. Finally, we show that our proposed 2D-MD SAC-OCDMA system outperforms existing solutions presented in the literature for LR-PON configuration, in terms of both aggregate bit rate and transmission reach.

Effect of fiber dispersion, content and aspect ratio on tensile strength of PP fiber reinforced soil

The present study was conducted to investigate the tensile strength characteristics of polypropylene (PP) fiber reinforced soil with different fiber dispersion, content and aspect ratio. In order to investigate this, the experimental programme was comprised by the test with a wide range of fiber content (0.35%, 0.60%, 0.85%), fiber aspect ratio (150, 225, 350), and mix patterns (discrete or random distribution). The results indicated that increases in fiber content caused an increment in the tensile strength whether discrete or random distribution. The increasing extent of tensile strength was different with increase of fiber aspect ratio under different fiber mix patterns. From experimental data, a genetic programming (GP) model was proposed for analyzing tensile strength contrast of the two mix patterns. In addition, the sensitive analysis of three inputs showed that aspect ratio has the greatest influence on the forecasting model. The effectiveness of the GP model was validated by the test results, and the robust model developed would provide a theoretical support for roadbase designing and construction which were reinforced with PP fibers.

On fibre dispersion in anisotropic soft biological tissues using fourth-order structural tensors

Developments in microscopic imaging techniques for soft biological tissues have greatly improved understanding of their underlying microstructures, notably the three-dimensional orientation and dispersion of fibrous constituents. In structural constitutive modelling, assuming that the collagenous and muscle fibres in soft tissues are perfectly aligned along a prescribed orientation can limit the ability to accurately predict the experimentally detected stress–strain response of biological samples. The objective of this paper is to extend the representation of hyperelasticity for anisotropic bodies using fourth-order structural tensors (FOSTs) to incorporate the effects of fibre dispersion according to the generalised structural tensor (GST) approach. Dispersion within a family of reinforcing collagen fibres is a common phenomenon in soft tissues which alters their overall mechanical behaviour. The FOST-based representation of the strain energy density function (SEF) separates the constitutive properties of the continuum from the nonlinear descriptions of geometric deformations; with each of these being described by different fourth-order tensors. The constant-valued material and structural properties of the continuum reside within fourth-order material tensors referred to as the anisotropic Lamé tensors. Nonlinearity in the model is then solely applied to the components of the displacement gradient tensor in fourth-order strain measures. The framework provided leads to a unique set of fourteen generalised FOSTs for two-direction preferred hyperelasticity including fibre families which are dispersed according to normalised distributions. In the absence of dispersion, the model collapses to the conventional FOST-based model. Models for the hyperelastic response of arterial wall and passive ventricular myocardium tissues are postulated and show good agreement with experimental data using minimal ground-state material constants.

Performance Evaluation of Highly Nonlinear Fiber (HNLF) Based Optical Phase Conjugation (OPC) in Long Haul Transmission of 640 Gbps 16-QAM CO-OFDM

This paper presents the quantitative measurement through an experimental test of 640 Gbps 16-QAM coherent-optical orthogonal frequency-division multiplexing (CO-OFDM) over 800 km optical fiber with mid-link optical phase conjugation (OPC) using highly nonlinear fiber (HNLF). The first focus is the OPC parameter optimization, including the optimization of HNLF length and signal/pump power that inputs into OPC. Four different HNLFs, as the illustrative examples, are investigated. The second focus is to investigate the effects of fiber dispersion, nonlinearity, and amplified spontaneous emission (ASE) noise on the long-haul transmission of 16-QAM CO-OFDM signal, and the OPC compensation efficiency. The performance evaluation focuses on the conversion efficiency (CE), received signal constellation, Q-factor improvement, and bit error rate (BER) at the receiver end. Such end-to-end performance evaluation is important because the 16-QAM CO-OFDM signal status is heterogeneous and the mitigation of transmission impairments to the signal is still unclear. The OPC parametric optimization is achieved experimentally using commercially available HNLFs with different scenarios and the numerical results are interpreted in conjunction with simulations.