Fiber Length Variation Research Articles

Modeling and numerical simulation of the gain spectrum of Thulium-doped broadband fiber amplifiers

Nowadays, due to the complex signal medium conversion process of semiconductor laser amplifiers, the optical fiber amplifier, which is a new type of all-optical amplifier, is increasingly used in optical fiber communication lines for signal amplification because it can directly perform all-optical amplification of signals and are especially suitable for relay amplification of long-distance optical communications. Our research project is the gain spectrum of the Thulium-doped broadband fiber amplifier. The signal wavelength range is from to . The goal is to obtain the gain spectrum with fiber length variation, doping concentration, and pump power. This paper follows a logical order that presents the introduction, the formulas used in the experiment, and the result and analysis. According to the output wavelength range, energy level structure, and electronic transition process, we designed the pump wavelength and established the rate and power propagation equations. Eventually, gain spectrum with a variation of fiber length, doping concentration, and pump power is available using MATLAB for programming and calculating. With our research achievement, a more efficient optical fiber amplifier is possible to be made in the future.

Optimization criteria and design of few-mode Erbium-doped fibers for cladding-pumped amplifiers.

We propose a novel optimization method that combines two design criteria to reduce the differential modal gain (DMG) in few-mode cladding-pumped erbium-doped fiber amplifiers (FM-EDFAs). In addition to the standard criterion that considers the mode intensity and dopant profile overlap, we introduce a second criterion that ensures that all doped regions have the same saturation behavior. With these two criteria, we define a figure-of-merit (FOM) that allows the design of FM-EDFAs with low DMG without high computational cost. We illustrate this method with the design of six-mode erbium-doped fibers (EDFs) for amplification over the C-Band targeting designs that are compatible with standard fabrication processes. The fibers have either a step-index or a staircase refractive index profile (RIP), with two ring-shaped erbium-doped regions in the core. With a staircase RIP, a fiber length of 29 m and 20 W of pump power injected in the cladding, our best design leads to a minimum gain of 22.6 dB while maintaining a DMGmax under 0.18 dB. We further show that the FOM optimization achieves a robust design with low DMG over a wide range of variations in signal power, pump power and fiber length.

Variability of main value-economic characteristics of F2-F4 hybrids of cotton in different soil-climate regions of Uzbekistan

One of the important problems in cotton breeding is the creation of high-yielding, fast-maturing varieties with high fiber yield and quality and their wide use in production. Due to the increase in the number of people on earth and the reduction of irrigated arable land, it is important to get a high quality harvest suitable for different soil and climate regions without expanding the arable land. This research intended to study the variability of the observed characters in the phenotype of the cotton plant during the selection of four F2-F4 hybrid combinations in the conditions of Tashkent, Fergana and Kashkadarya regions. During the research experiments, classical genetic-selection methods of cotton, hybridological analysis methods, comparative morphology, phenological observations and genetic-statistical analysis methods were used. The results showed that the average indicators of this sign were approximately the same in Fergana and Kashkadarya regions, accounted for 116.5 and 117 days, which was 12 days shorter than the growth period of this hybrid in Tashkent region. Similarly, insignificant changes of the above combinations were also observed in the experiments of 2019 and 2020. It was found that in F2 [(F8 L-247 x S-484) x F15 L-248], the fiber length variation was not significantly affected by the environment, the variation ranged from 0.04 inches to 0.07 inches.

The Effect of Fiber Length Variations on the Composite Fiber of Oil Palm Empty Bunches (OPEB) on Tensile Strength

Composite is a combination of materials formed from mixing between two or more of the forming materials. This research aims to determine the effect of variations in fiber length with lengths of 4cm, 6cm, and 8cm with a volume fraction of OPEFB fiber of 30% and NaOH alkaline immersion for 2 hours. The tests carried out were tensile testing using ASTM D3039 and bending testing using ASTM D7264. Based on the study's results with the 30% OPEFB fraction with the highest tensile strength yield, the 8cm fiber length of 13,33 MPa was achieved. Meanwhile, the lowest value was achieved with a length of 4cm of 3,2MPa.

Prediction of UCS and CBR behavior of fiber-reinforced municipal solid waste incinerator bottom ash composites using experimental and machine learning methods

The present study deals with the evaluation of municipal solid waste incinerator bottom ash under the various design parameters considering Geotechnical and Geoenvironmental engineering applications of bottom ash. The effect of fiber-reinforced cement stabilized municipal solid waste incinerator bottom ash at varied cement and fiber content is studied. A set of 117 Unconfined compressive strength and 97 California bearing ratio tests were performed for 13 mm and 19 mm polypropylene fibers. The experimental results confirmed that the addition of 1 % fiber and 9 % cement leads to a maximum advancement of Unconfined compressive strength and California bearing ratio values. The results show the applicability of these materials for constructing roads, embankments, and compacted fills. Selecting a set of variables from the experimental results, the machine learning models- Artificial Neural Networks, Adaptive Neuro-Fuzzy Inference systems, and Multilinear regression models were used to predict these results. Varying the cement percentage, fiber content, fiber length, and curing period, the experimental unconfined compressive strength and California bearing ratio values were calculated, and the same is compared with machine learning models. The results were found to be suitable for predicting unconfined compressive strength and California bearing ratio values. During the study, the results produced from Multilinear regression were observed to be less significant. In addition, SEM analysis of the experimented specimens was conducted to comment on the strength development due to variations in cement content, fiber content, and fiber length, after 28 days of curing. The proposed models resulted in reliable results and thus can be used to avoid time-consuming mechanical lab tests.

Hemp fiber reinforced one-part alkali-activated composites with expanded perlite: Mechanical properties, microstructure analysis and high-temperature resistance

The objective of the current research is to find out what impacts hemp fibers (HF) lengths and percentages have on the fresh, physical, mechanical, sorptivity, dry shrinkage, and thermal properties of HF-reinforced alkali-activated composite (AAC) reinforced with ground blast furnace slag (GBFS). Two groups of AAC mixes with 10 and 20 mm HF lengths were produced. Each group contained different percentages of HF with varying fiber lengths added to mixes at 0.5 %, 1 %, 2 %, and 3.0 % by weight of cement, respectively. Flow diameters were measured to determine the fresh-state properties of the AACs. Water absorption and apparent porosity were determined as physical properties. The unit weights of AAC mixtures are between 1045–1672 kg/m3. Measurements were made on compression and flexural characteristics at 7 and 28 days. The 28-day compressive strengths of AAC mixtures vary between 1.28 and 2.73 MPa, and the bending strengths vary between 0.48 and 1.65 MPa. AAC was also tested for water absorption, drying shrinkage, thermal conductivity, fresh and dry unit weight and porosity. The resistance of high temperatures at 250, 500, and 750 °C was determined. There is a significant improvement in compressive and flexural strength and thermal conductivity when HF is added at a 20 mm length. This improvement was confirmed and emphasized through scanning electron microscopy (SEM). According to study results, high-temperature alkali cooking treatments up to 250 °C may improve the thermal stability of HF cellulose. The best HF mix, M2-2 %, increased the 28-day compressive strength by 28.8 % and produced the best results at temperatures as high as 750 °C. The compressive strength of the mixtures exposed to 750 °C was obtained as approximately 2 MPa.

Dynamic Compression Mechanical Properties of Polyoxymethylene-Fiber-Reinforced Concrete.

The excellent overall performance of polyoxymethylene (POM) fiber enables it to show great potential for engineering applications. The effect of POM fibers on the dynamic compression mechanical properties of concrete is an important issue for its application in engineering structures such as airport pavement and bridges. It is necessary to investigate the dynamic compressive mechanical properties of POM-fiber-reinforced concrete (PFRC) under impact loading. The PFRC specimens with various POM fiber lengths (6, 8, 12, 16, and 24 mm) and ordinary-performance concrete (OPC) specimens were tested by utilizing the split Hopkinson pressure bar (SHPB). We studied the effect of fiber length and strain rate on the dynamic compression mechanical properties of PFRC and established a damage dynamic constitutive model for PFRC. The results indicate that the dynamic compressive strength, peak strain, ultimate strain, dynamic peak toughness, dynamic ultimate toughness, and dynamic increase factor (DIF) of the PFRC increased obviously with the increase in strain rate. POM fiber was found to be able to effectively improve the deformation ability and impact toughness of concrete. The dynamic compressive strength and impact toughness of PFRC with a fiber length of 8 mm was optimal at different strain rates. The POM fibers with 16 mm and 24 mm lengths negatively affected the dynamic compressive strength of the concrete. The fiber length variation had an insignificant effect on the DIF of PFRC. The established damage dynamic constitutive model for PFRC was fitted and analyzed, and it was found that the model is able to describe the dynamic characteristics of PFRC well. This study can extend POM fibers to engineering structures that may be subjected to impact loading and act as a reference for the design of PFRC under impact loading.

Comparative study on the continuous-wave double-cladding Yb-doped fiber amplifiers operating around 978 nm and 982 nm

The comparative study on the continuous-wave double-cladding Yb-doped fiber (DCYF) amplifiers operating around 978 nm and 982 nm is carried out in this paper. By means of numerical and experimental studies, it is revealed that compared with 978-nm amplifiers, the amplified spontaneous emission (ASE) around 1030 nm can be better suppressed in 982-nm amplifiers because of the lower requirement of population inversion for the amplification of 982-nm signal light, and thus, the larger optimum active fiber length and slope efficiency can be obtained in 982-nm amplifiers. This should be the first experimental demonstration that the slope efficiency of 982-nm amplifiers can be larger than that of 978-nm amplifiers, to the best of our knowledge. The effect of signal wavelength on the slope efficiency of amplifiers is also numerically studied. It is found that the optimum signal wavelength varies from the 982 nm to 980 nm with the increment of pump light. It is also found that the variation of optimum fiber length with the pump power in the case of signal wavelength longer than 986 nm is different from that with the signal wavelength shorter than 984 nm. The pertinent explanation is also given.

Analisis Pengaruh Pencampuran Serat Karbon Terhadap Kekuatan Beton dalam Menahan Beban Desak, Beban Tarik dan Beban Lentur

This study aims to overcome the weaknesses of concrete, namely the nature of concrete which is classified as brittle so that it has a negative impact on the concrete in resisting bending and splitting, while it also has a high density (2.3-2.4 T / m3). So that this research will add fiber to concrete in the form of carbon fiber, carbon fiber that is very strong and is known to be very light is expected to increase the tensile strength and flexural concrete significantly and without adding weight to itself. Calculation of concrete mix planning using normal concrete mixture calculations (SNI 03-2834-2000) with a planned compressive strength is 20 MPa, carbon fiber mixed in the form of fiber pieces with variations in fiber length, namely 5mm, 10mm and 15mm with a composition of 0.4% of normal concrete weight. Tests are carried out when the concrete sample is 28 days old. While waiting for the concrete age to reach 28 days, the concrete is treated in the form of soaking in water. And the results of this study indicate a significant increase in concrete compressive strength of 45.32%; concrete tensile strength of 73.24%; and the flexural strength of the concrete was 78.83% but it also managed to maintain the density of concrete at 2.3 T / m3. For further discussion and more detail will be presented in the following research report.

Stabilized Time Transfer via a 1000-km Optical Fiber Link Using High-Precision Delay Compensation System

Variations in optical fiber length and refractive index are induced by environmental perturbation, resulting in an additional dynamic propagation delay in fiber-based time synchronization systems, which deteriorate their transfer stability. This disadvantage can be significantly reduced by transmitting the time signal in both directions through fiber and constructing a feedback loop to compensate the propagation delay at the remote end of the link. This paper proposes an analog-digital hybrid proportional integral derivative (PID) control compensation system based on the time-frequency phase-locked loop (TF-PLL). The system is designed to keep the merits of wide servo bandwidth, servo accuracy, and a large dynamic delay compensation range up to 1 s, which is much greater than that reported in previous studies. For proving the validity of this proposed scheme, a self-developed optical fiber time synchronization equipment based on the delay compensation system is applied. The delay compensation system is used on a 1100-km long laboratory optical fiber, and the results show that the time synchronization stability in terms of time deviation (TDEV) is less than 5.92 ps/1 s and 2.56 ps/10,000 s. After successful laboratory evaluation, the proposed system is installed on a real 988.48-km line between the Xi’an Lintong branch of the National Time Service Center (NTSC) and Linfen City, Shanxi Province, realizing the time synchronization of 10 stations along the optical fiber link. The experimental results in the 988.48-km link illustrate that the measured time difference with a peak-to-peak value of 176 ps, the standard deviation of 19.3 ps, and a TDEV of less than 10.49 ps/1 s and 2.31 ps/40,000 s is achieved. The high-precision time delay compensation system proposed in this paper is simple, reliable, and accurate; has a wide range of compensation; and opens up a feasible scheme for providing synchronized time signals to multiple users over the long-distance field optical fiber networks.

Experimental Investigation of Effect of Fiber Length on Mechanical, Wear, and Morphological Behavior of Silane-Treated Pineapple Leaf Fiber Reinforced Polymer Composites

The development of the best properties in polyester composite from pineapple leaf fiber (PALF) as a reinforcing material is a subject of interest. The properties of PALF are reliant upon fiber length, wherein technical difficulties in production of long fibers and processing for better characteristics in polyester composites possess inherent challenges. The PALFs are subjected to silane treatment for altering fiber properties. This research attempts to analyze the impact of silane-treated PALF with varying fiber lengths (5, 10, 15, 20, and 25 mm) on the performance of natural fiber composites (NFC) properties. Open mold and hand lay-up techniques were employed to develop the polyester composites. The prepared PALF-based polyester composites were examined for different properties (impact, flexural, tensile strength, and wear rate). Coefficient of friction and wear studies are performed on the prepared composites subjected to different loads (10, 20, and 30 N) via a pin on disc test rig. Polymer composite fracture surfaces were analyzed to observe the interfacial bonding between fibers and matrix via scanning electron microscopy (SEM). SEM results showed that the application of silane treatment resulted in better surface topography (fiber length of 5–10 mm showed smooth surface resulted in crack proliferation possessing low fracture toughness of 15–32 MPa; whereas a 15–20 mm fiber length resulted in better fiber–matrix bonding, improving the fracture toughness from 42–55 MPa) as a result of change in chemical structure in PALF. The 20 mm length of PALF resulted in better properties (flexural, tensile, impact, and wear resistance) which are attributed to fiber–matrix interfacial bonding. These properties ensure the developed polymer composites can be applied to walls, building insulation, and artificial ceilings.

Liquid Repellence of Phobic Fiber Networks.

The wetting behavior of fiber networks, which are central to many research and industrial applications, can be difficult to predict accurately owing to their complex, heterogeneous structure. The cylindrical pore model, widely used to interpret and predict the forced wetting of hydrophobic porous materials, often does not yield correct results when working with fibrous networks like paper substrates and non-woven fabrics. This is because these materials exhibit variation in pore size, fiber length, and fiber diameter, as well as a reentrant pore geometry. Quantitative prediction of the critical wetting resistance of hydrophobized papers to arbitrary entrant liquids requires a more sophisticated analytical approach that considers this unique fibrous structure and the effect of stochastic variations within the pore matrix. In this work, we directly measure the critical breakthrough pressure for different porous substrates across various wetting entrant liquids. To isolate the effects of the structure and stochastics on critical wetting behavior of fibrous networks, we analyze additional materials strategically chosen for their subsets of structural features. Ultimately, we formulate a method that demonstrates physical reasonableness, numerical accuracy, and the ability to elucidate the effects of pore size, pore size distribution, fiber diameter, fiber diameter distribution, surface wettability, and liquid surface tension on critical breakthrough pressure of liquids through hydrophobic fibrous networks.

A hierarchical multi-scale analytical approach for predicting the elastic behavior of short fiber reinforced polymers under triaxial and flexural loading conditions

This paper presents a computationally efficient multi-scale analytical framework for predicting the effective elastic response of short fiber reinforced polymers (SFRPs) under triaxial and flexural loading conditions where the details of microstructure such as core/shell thickness, volume fraction distribution, fiber misalignment and fiber length variation are objectively taken into account. To this end, the mean-field homogenization and finite element approaches are compared to calculate the elastic response of SFRPs at the microscopic level while the orientation averaging approach is used to address the effects of fiber misalignment. The obtained mechanical behavior is then linked to an enhanced laminate theory to predict the effective triaxial and bending macrostructural behavior considering the core/shell effects and variation of volume fraction through the thickness. Using the second-order homogenization technique, the numerical validation of the proposed analytical approach is investigated based on the micro- and meso-scale analyses. Furthermore, the potential of the proposed strategy is demonstrated for hybrid composites. Finally, the accuracy of the suggested model is thoroughly studied using the available experimental tests in literature where the statistical information about the details of SFRP microstructures is presented.

Disaggregation of Ploidy, Gender, and Genotype Effects on Wood and Fiber Traits in a Diploid and Triploid Hybrid Poplar Family.

Triploid breeding based on unilateral sexual polyploidization is an effective approach for genetic improvement of Populus, which can integrate heterosis and ploidy vigor in an elite variety. However, the phenotypic divergence of unselected allotriploids with the same cross-combination remains poorly understood, and the contributions of ploidy, gender, and genotype effects on phenotypic variation are still unclear. In this study, wood and fiber traits, including basic density (BD), lignin content (LC), fiber length (FL), fiber width (FW), and fiber length/width (FL/W), were measured based on a 10-year-old clonal trial, including full-sib diploid and triploid hybrids of (Populus pseudo-simonii × P. nigra ‘Zheyin3#’) × P. × beijingensis, and contributions of ploidy, gender, and genotype effects on the variation of these traits, were disaggregated to enhance our understanding of triploid breeding. We found a significant phenotypic variation for all measured traits among genotypes. All the wood and fiber traits studied here underwent strong clonal responses with high repeatabilities (0.55–0.76). The Pearson’s correlation analyses based on the best linear unbiased predictors (BLUPs) revealed that BD was significantly positively correlated with FL (r = 0.65, p = 0.030), suggesting that BD could be improved together with FL during triploid breeding. The FL of the triploids was significantly larger than that of the diploids (p < 0.001), suggesting that ploidy strongly affected the variation of FL traits. The difference between females and males was not significant for any measured trait, implying that gender might not be a major factor for variation in these traits. Further analyses of variance components showed that genotype dominantly contributed to the variation of BD, LC, and FW traits (with 54, 62, and 53% contributions, respectively) and ploidy contributed strongly to variation in FL and FL/W (77 and 50%, respectively). The genetic coefficient of variation (CVG) of triploids for each trait was low, suggesting that it is necessary to produce many triploids for selection or to use different Populus species as parents. Our findings provide new insights into the genetic effects of ploidy, gender, and genotype on wood and fiber traits within a full-sib poplar family, enhancing the understanding of the triploid breeding program of Populus.

Investigation of a Multivariate Correction Method for HVI Fibrogram Measurements

Cotton fiber length parameters are used across the cotton industry to select elite germplasm, purchase cotton bales and manage mill throughput. The High Volume Instrument (HVI) provides the most commonly used fiber length parameters, upper half mean length (UHML) and uniformity index (UI). UI is the ratio of mean length (ML) to the UHML expressed as a percentage. These length parameters, UHML and ML, are generated following the fibrograph principle and are highly correlated with two span lengths on the fibrogram curve. These two length parameters represent a small part of the fibrogram and do not characterize the total within-sample variation. In previous studies, we found that fiber length variation captured by the whole fibrogram improves the prediction of yarn quality. However, HVIs are currently calibrated for UHML and UI. In this study, we investigated a correction method using a set of 461 commercial samples to correct the whole fibrogram curve across HVIs and validated the method using an independent set of 932 commercial samples. The correction procedure lowers the Euclidian distance between fibrograms as much as 35%, bringing the fibrogram measurements into agreement across multiple HVIs. This indicates that the whole fibrogram could be used to improve HVI fiber length measurements across the cotton industry.

Optimization and characterization of surface treated Lagenaria siceraria fiber and its reinforcement effect on epoxy composites

PurposeThis paper aims to investigate the resultant optimal ultimate tensile strength, elongation, flexural strength and modulus, compression strength and impact strength of fabricated alkali-treated Lagenaria siceraria fiber (LSF)-reinforced polymer matrix composite by optimizing input factors and microstructural characterization by influencing fiber length, fiber concentration and treatment condition of LSF.Design/methodology/approachThe fabrication of LSF-reinforced composite specimens involved surface treatment followed by custom experimental design using a simple hand layup process. The wear analysis was performed by a multi-tribotester TR25 machine, and the developed model was validated by using statistical software Design Expert V.8 and analysis of variance (ANOVA). The surface morphology of the sample was also analyzed by field emission scanning electron microscopy.FindingsThe alkali treatment for LSFs had reduced the hemicellulose, and enhanced mechanical performance was observed for 30 wt.% concentration of L. siceraria in epoxy resin. Thermogravimetric analysis revealed thermal stability up to 245°C; microstructure revealed fiber entanglements in case of longer fiber length and compression strength reduction; and the surface-treated fiber composites exhibited reduced occurrences of defects and enhanced matrix–fiber bonding. Enhanced mechanical performances were observed, namely, ultimate tensile strength of 17.072 MPa, elongation of 1.847%, flexural strength of 50.4 MPa, flexural modulus of 3,376.31 GPa, compression strength of 52.154 MPa and impact strength of 0.53 joules.Originality/valueThe novel approach of optimizing and characterizing alkali surface-treated LSF-reinforced epoxy matrix composite was explored, varying fiber length and concentrations for specimens by empirical relations and experimental design to obtain optimal performance validated by ANOVA. Enhanced properties were obtained for: 7 mm fiber length and 30 wt.% concentration of fiber in the composite for alkali-treated fiber.

Integrity and crack resistance of hybrid polypropylene fiber reinforced cemented soil

Cement is commonly used in the rapid construction of emergency airports; however, cemented soils have issues with integrity and crack resistance. For example, cemented soils can crack easily, and overall stability is insufficient. To address these problems, cemented soil is reinforced with hybrid polypropylene fiber, and the anti-flying property, anti-wear property, and crack resistance of polypropylene fiber reinforced cemented soil with varying fiber lengths, fiber contents, and fiber combinations are examined through flying tests, wear tests, and crack tests. Results show that the reinforcement of fiber can significantly improve the anti-flying property, anti-wear property, and crack resistance of cemented soil. The content and fiber length have a great impact on properties of fiber reinforced cemented soil. The ideal length and content of fine polypropylene fiber are 12 mm and 0.3%, respectively. The ideal combination of hybrid polypropylene fiber reinforced cemented soil is 0.3% coarse polypropylene fiber with the length of 38 mm and 0.3% fine polypropylene fiber with the length of 12 mm. In addition, hybrid polypropylene fiber reinforced cemented soil mechanical properties exceed those of single polypropylene fiber reinforced cemented soil.

Short fiber‐reinforced oxide fiber composites

AbstractThis paper presents a novel fiber spraying process for the manufacturing of short fiber bundle‐reinforced Nextel™ 610/Al2O3‐ZrO2 oxide fiber composites (SF‐OFC) and its characterization. First, the influence of varying fiber lengths (7, 14, and 28 mm, continuous fibers) and fiber orientations (unidirectional 0°, quasi‐isotropic, ±45°) was investigated using hand‐laid SF‐OFC. Due to the weak matrix, the hand‐laid material exhibited a strongly fiber‐dominated material behavior, that is, variations in fiber length and orientation had a strong influence on the material properties. Second, the automated sprayed SF‐OFC, however, exhibited a random orientation of the fiber bundles, which resulted in in‐plane isotropic material properties. Average bending strengths of up to 177 MPa, strains of .39%, and a quasi‐ductile fracture behavior were achieved. The strain was, therefore, in the range of fabric‐reinforced OFC. While the bending strength of the SF‐OFC was somewhat lower than that of fabric‐reinforced OFC with the fiber orientation parallel to the loading direction, it was more than two times higher than the strength in 45° direction relative to the fabric reinforcement. Combined with good drapability and lower material costs compared to fabric‐reinforced OFC, SF‐OFC is, therefore, a promising material for industrial applications.

Impact of Addition of Banana Fibres at Varying Fibre Length and Content on Mechanical and Microstructural Properties of Concrete

This experimental study aimed at investigating the impact of addition of banana fibres on the mechanical (compression, splitting tension, and flexure) and microstructural (microscopic morphology and Energy Dispersive X-ray Spectroscopy) properties of concrete. Concrete mixes comprising of banana fibres of varying fibre lengths (40, 50, and 60 mm) and fibre contents (0.1, 0.2, 1.0, 1.5, and 2.5%) were assessed. Addition of banana fibres to concrete was observed to significantly impact on compressive strength only at lower fibre contents of up to 0.25% for all fibre lengths. Fibre length had no significant impact on compressive strength at lower fibre contents of up to 0.25%, but shorter fibres were observed to perform better than longer ones at higher dosages more than 0.25%. Increase in fibre content positively impacted on tensile strength of concrete at relatively lower fibre dosages of up to 1%. Similarly, fibre length impacted on tensile strength of concrete at lower fibre contents of up to 1% and, longer fibres were observed to be more effective than shorter ones. Addition of banana fibres generally did not greatly contribute to flexural strength of concrete but had a marginal impact only when shorter fibres were used at lower fibre dosages. Also, microstructure of concrete was improved through better bonding between the fibres and the matrix and reduction in porosity of the matrix, which resulted in improved mechanical properties of the composite. Banana fibres further contributed to changes in phases of the composite structure of Banana fibre-reinforced concrete (BFRC) through a reduction in its interplanar spacing and lattice structure. For optimal purposes, addition of banana fibres should be limited to a maximum of 1% fibre content preferably using shorter fibre lengths. Further research to improve flexural strength of BFRC to meet minimum technical requirements is required before it can be considered for structural applications.

High Peak Power Q-switched Er:ZBLAN Fiber Laser

A practical realization of a diode pumped actively Q-switched Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fluoride fiber laser operating near 2.78 μm is reported. For the repetition rate of 100 Hz stable 26 ns pulses with an energy of 330 μJ and peak power of 12.7 kW are demonstrated. The laser performance is tested against variations in pump power, repetition rate and active fiber length.