Longer Fibers Research Articles

Influence of released air on effective backwashing length in dead-end hollow fiber membrane system

To obtain a better backwashing strategy, effects of released air on the effective backwashing length of dead-end hollow fiber membranes were investigated in this study. Ultrasonic spectrum and AGU-Vallen Wavelet software were imported to ensure a more intuitive understanding on effects of released air from echoes. Modeling and experimental results in this study showed that the air accumulation at the most distant membrane point was a recombination process which contained air release and dissolution. The recombination process contained air release as the pressure type changed from inside-outside to outside-inside and air dissolution in the outside-inside pressure condition. Moreover, longer fiber was more prone to the air accumulation in the most distant membrane lumen. The mathematical model predicted the volume of final remaining air that depended on the instantaneous pressure difference, backwashing flux, backwashing duration, membrane surface area, water viscosity and temperature. Experimental verification of ultrasonic waveforms was consistent with the model prediction. To overcome the effects brought by released air and maintain backwashing effectiveness, a novel method was developed by adding a segment of gas filtration membrane at the end of the hollow fiber which had finally extended the effective backwashing length. These studies were expected to have implications for the design and operation of hollow fiber membrane backwashing.

Feasibility of Reducing the Fiber Content in Ultra-High-Performance Fiber-Reinforced Concrete under Flexure.

In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths (lf) of 13, 19.5, and 30 mm and four different volume fractions (vf) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, such as flexural strength, deflection capacity, toughness, and cracking behavior, improve with increasing fiber length and volume fraction, while first-cracking properties are not significantly influenced by fiber length and volume fraction. A 0.5 vol % reduction of steel fiber content relative to commercial UHPFRC can be achieved without deterioration of flexural performance by replacing short fibers (lf of 13 mm) with longer fibers (lf of 19.5 mm and 30 mm).

EXPECTATION REGARDING HIGHER LOAD CAPACITY OF LONG-FIBER-REINFORCED PLASTIC GEAR PAIRS

To be improved their strengths and stiffnesses, some plastic materials are reinforced with fibers. However, even such fiber-reinforced plastics have never obtained sufficient strengths for power transmission gear pairs. Generally, fibers of the reinforcement are 0.1 mm long, so that they could not entwine. Meanwhile, much longer fibers have been launched for plastic reinforcement. They are some mm long, so that such longer fibers could entwine as fluff balls, and could form 3-dimensional networks in parts. This could enables higher strengths and stiffnesses to be achieved. The present paper describes gear running tests for evaluating load capacity of long-fiber-reinforced PA66 gear pairs. In addition, observations of fiber distributions in injection-molded gears with an X-ray CT scanning causes molding conditions to be improved. As a results, some lubricants yielded much higher load capacities of long fiber-reinforced PA66 gear pairs than those of usual-fiber-reinforced ones. In this paper, only 33 weight percent glass fibers were discussed, but 60 weight percent ones are also available. They might be expected to show much higher load capacities of gear pairs.

Disruption of FGF5 in Cashmere Goats Using CRISPR/Cas9 Results in More Secondary Hair Follicles and Longer Fibers.

Precision genetic engineering accelerates the genetic improvement of livestock for agriculture and biomedicine. We have recently reported our success in producing gene-modified goats using the CRISPR/Cas9 system through microinjection of Cas9 mRNA and sgRNAs targeting the MSTN and FGF5 genes in goat embryos. By investigating the influence of gene modification on the phenotypes of Cas9-mediated goats, we herein demonstrate that the utility of this approach involving the disruption of FGF5 results in increased number of second hair follicles and enhanced fiber length in Cas9-mediated goats, suggesting more cashmere will be produced. The effects of genome modifications were characterized using H&E and immunohistochemistry staining, quantitative PCR, and western blotting techniques. These results indicated that the gene modifications induced by the disruption of FGF5 had occurred at the morphological and genetic levels. We further show that the knockout alleles were likely capable of germline transmission, which is essential for goat population expansion. These results provide sufficient evidences of the merit of using the CRISPR/Cas9 approach for the generation of gene-modified goats displaying the corresponding mutant phenotypes.

Gain Enhancement of Single-Mode Cr-Doped Core Fibers by Online Growth System

Gain enhancement of single-mode Cr-doped crystalline core fiber (SMCDCCF) with longer fiber length fabricated by online laser-heated pedestal growth (LHPG) technique is demonstrated. In comparison with the SMCDCCF fabricated without online growth, the online technique enables real-time monitoring and controlling small molten zone in the LHPG to achieve longer length with better uniformity and smaller core diameter of the SMCDCCFs. The SMCDCCF exhibits a length of 10.6 cm, a core diameter of 25 mu m, and a V-value of 2.40, which confirms the LP01 single-mode operation by the far-field pattern measurement. A 3.9-dB gross gain and a 1.9-dB net gain of the SMCDCCF at the wavelength of 1400 nm were obtained. The gross and net gains are the highest yet reported of the SMCDCCFs. Further development on higher gain of the SMCDCCF may be functioned the SMCDCCF as a broadband fiber amplifier for use in the next-generation fiber transmission systems.

Correlation between Pod Shape Traits and Its Fiber Quality of Wild Calotropis Gigantea

ABSTRACTSeed fiber in the Calotropis gigantea (C. gigantea) pods is the most valuable component and can be developed into textile material. Cultivating high-yield and high-quality seed fibers for C. gigantea is one of the critical preconditions for its textile industrialization. In this paper, pods picked from wild C. gigantea plants were used as the experimental materials. The fiber length distribution of the pods was studied. The pod characters (pod shape, single pod weight, fiber weight per pod and seed number per pod, etc.) and the crucial quality characteristics of seed fibers (length, diameter and strength) were tested. The correlations between them were analyzed. The results show that the fiber lengths at the tip, the petiole and the middle part of the pods are significantly different: the fibers from the two sides of the middle part are the longest and more uniform. The pod shape is closely correlated with the fiber length, fineness and strength: longer pods have longer fiber length, smaller length variation and larger fiber diameter, and the percentage of low strength fiber (single fiber strength <1.2 cN) is significantly lower compared to smaller pods. Cultivating C. gigantea with large size and heavy pods will improve the seed fiber yield and the fiber quality.

Impact Properties of Hemp Fibre Reinforced Cementitious Composites

The construction industry has seen an incredibly fast increase in utilizing natural fibres for making low-cost building materials to achieve sustainable construction. One of such applications is natural fibre-reinforced cementitious materials for either structural or non-structural purpose. Impact properties are engineering properties received increasing attentions from engineering community for structural materials. This research therefore studies impact resistance of hemp fibre reinforced cementitious composites at early ages. Hemp fibre with various lengths, 10 mm and 20 mm, are utilized to reinforce cementitious materials. Hemp fibre reinforced cementitious composite slabs were tested under repeating dropping mass till failure at the age of 7, 14 and 28 days. Cracking behaviour, impact resistance, absorbed impact energy and survived impact blows upon failure are qualitatively/quantitatively analysed. It has been found that 20 mm-long hemp fibre reinforcement leads to higher impact resistance, more absorbed impact energy and survived more impact blows upon failure. Cementitious composite slabs reinforced by 20 mm-long hemp fibres exhibit higher impact crack resistance ratio than those reinforced by 10 mm-long fibres. Longer fibres are more effective in inhibiting the growth of micro-cracks and blunting the propagation of micro-cracks before they join up to form macro cracks leading to ultimate failure.

Variations in Fiber Morphology and Chemical Components of Dendrocalamus giganteus

Abstract The fiber and chemical properties of Dendrocalamus giganteus at three ages from three different sites in China were investigated. For samples from all sites, the fibers in the middle internodes of culms were longer than those of other internodes. A similar trend was also observed within one internode. The fiber achieved its maximum length after 1 year, but the maximum length differed with site. The chemical composition and fiber characteristics also varied with height and site. Bamboo culms at the age of 3 years were suitable for utilization purposes, and the bamboos of Cangyuan provenance were the best for pulping and processing. They were also more suitable for popularization as a timber-yielding type owing to having the longest fibers and the lowest ratio of wall thickness to lumen diameter, the lowest SiO2 and lignin contents, and the highest holocellulose content.

Centrifuge Modeling and Digital Image Cross-Correlation Analysis of Geofiber-Reinforced Clay-Based Landfill Covers

AbstractThe influence of discrete and randomly distributed fibers (DRDF) on the improvement of the resistance to cracking of clay-based landfill covers was studied by conducting a series of centrifuge model tests. A motor-based differential settlement simulator (MDSS) was used to induce differential settlements to the soil layers during centrifuge tests performed at 40g using the 4.5 m radius beam centrifuge at Indian Institute of Technology Bombay. A digital image cross-correlation (DIC) technique was used to capture deformations of the model barriers and to obtain strain field distributions. Thickness of the unreinforced barriers (URSB) and fiber-reinforced barriers (FRSB) were varied as 15 mm (similar to 0.6 m in the field) and 25 mm (1.0 m). Fiber lengths were varied as 30, 60, and 90 mm. The strain at water breakthrough of 15 mm (0.6 m) and 25 mm (1 m) FRSB were respectively 1.9 and 2.2 times higher compared to identical URSBs. A relatively crack-free surface was observed for FRSB with longer fibers ...

Memory-based pulse amplitude modulation for short-reach fiber communications with intensity modulation and direct detection.

The low cost of an intensity modulation and direct detection system has made it an attractive choice for short-reach fiber communications. A longer fiber transmission length can be supported with the help of a combination of high-ary pulse amplitude modulation (PAM) and maximum likelihood sequence estimation (MLSE). For a further improvement on the system performance under a fiber dispersive channel, this paper proposes to add memory into PAM for spectrum compression. The memory-based PAM can be implemented with a simple pre-coding at the transmitter side while no extra requirement is necessary on the receiver side. Both theoretical and simulation results show that the memory-based PAM has a smaller mainlobe bandwidth and thus has a higher tolerance to the accumulated fiber dispersion. Compared with conventional memory-less PAM-4, the memory-based PAM-4 can effectively extend the maximum achievable fiber transmission length from 60km to 70km with the same number of MLSE states at the receiver. Moreover, this paper also proposes an optimization on the memory-based PAM and a further extension on the allowed fiber transmission length is achieved.

A durable, high-performance hollow-nanofiber cathode for intermediate-temperature fuel cells

Hollow nanofibers of PrBa0.5Sr0.5Co2O5+δ (PBSC), created by an electrospinning process, are assembled into a three dimensional (3D) fibrous porous electrode, providing facile pathways for gas transport and excellent electrical conductivity for efficient charge transfer and, thus, greatly enhancing the rate of oxygen reduction reactions (ORR), as confirmed by the small electrode polarization resistance and low activation energy. A simple geometric modeling suggests that an electrode with longer fibers tends to be more efficient in facilitating mass and charge transfer under the conditions studied. A solid oxide fuel cell based on this 3D fibrous cathode demonstrates a peak power density of 1.11Wcm−2 at 550°C when humidified H2 was used as fuel and ambient air as oxidant. The fibrous architecture also shows excellent stability under the operating conditions. Further and in particular, the high-performance hollow-fiber electrodes are also applicable to other energy storage and conversion systems.

Spatial distribution of potassium uptake across the cotton plant affects fiber length

To enhance whole plant fiber quality of cotton, the relationship between the spatial distribution of potassium (K) absorption and fiber length was investigated. In 2007, a field experiment was conducted to assess genotypic differences among 17 cultivars for potassium absorption and fiber length. Differences in both K uptake and fiber length existed among cultivars in field conditions. The cultivars could be categorized into three classes: moderate K uptake and high fiber length; high K uptake and moderate fiber length; and both low K uptake fiber length. In 2008, single cultivars representative of each of these three classes were selected to further investigate spatial distribution patterns of K absorption and cotton fiber length, respectively. In 2009, differences among the three selected cultivars in K uptake and fiber length were further studied under three K fertilizer regimes and by foliar spraying of KCl. Higher K uptake at upper and distal positions of the plant was associated with longer fiber; however, at lower and proximal positions no such association was observed. The change of K uptake and fiber length is related to cultivar and K fertilizer application as well. For all three cultivars, without K fertilizer application, K uptake and fiber length decreased from lower to upper sections and from proximal to distal positions. With increasing K application, K uptake increased for all positions, especially upper and distal positions. For cultivar Siza3, higher fiber lengths were consistent with greater K uptake at upper and distal sections. For cultivar Xuza3, fiber length declined markedly when K application rate increased from 225 to 450kghm−1 even if K absorption was enhanced. For Sumian9, fiber lengths were no longer increased when K rate increased from 225 to 450kghm−1. These results suggested that rational K fertilizer management could improve whole plant fiber length of cotton cultivars that have intermediate K absorption potential with high uptake ability at upper and distal positions.

Wood anatomy and acoustic properties of selected tropical hardwoods

Selected anatomical features and ground tissue composition were studied in four tropical hardwoods (Afzelia sp. [Doussié], Intsia sp. [Merbau], Astronium sp. [Muiracatiara] and Millettia sp. [Wengé]). These woods can be applied in musical instrument production, especially for xylophone bars. The measured density, 1st bending natural frequency and the logarithmic decrement of damping were used to calculate other acoustic properties such as dynamic young modulus of elasticity (Erf), specific modulus of elasticity (E´/ρ), internal friction (tan δ), and acoustic conversion efficiency (ACE). The correlations between anatomy and acoustic properties were determined. Despite difficulties in specifying general characteristics of hardwoods due to their complicated and variable structure, correlations valid between species were found for specific modulus of elasticity. Specific modulus of elasticity was negatively correlated with ray tissue volume and positively with ray height to width ratio and fiber length. The diversity in ground tissue composition was the main criterion for the species choice and probably should condition diverse correlations of anatomical features found for individual species. It seems that better acoustic properties (higher stiffness, ACE or specific modulus of elasticity) are performed by wood with longer fibers and slender rays, causing minimal deflection of adjoining fibers.

Thermal Expansion of Aluminate Cement-Based Composite Containing Basalt Fibres with Different Length

This article is focused on thermal expansion of cement-based composite. Studied materials are concrete containing alumina cement, silica aggregates and they are reinforced by basalt fibres. Three different concrete varying in fibres length were prepared and its basic physical properties and thermal expansion were measured. Fibres lengths were 6mm and 12mm. Total amount of fibres in mixtures were constant, whereas the ratio of the fibers were changed. Results were compared with reference concrete with no fibres. It was proved positive effect of fibres on thermal expansion, when the lowest values of thermal strain were shown by material with just longer fibres.

Explore the method of repairing bone defect after resection of lower extremity long bone structure fiber

Objective To analyze the repair methods of bone defects caused by the harmful removal of lower extremity long bone segmental bone fibrous structure, and to provide reference for clinical treatment. Methods Six cases of patient with adverse fibrous structure,3 cases with the jnjury of backbone of the tibia and 3 cases of femoral shaft damage were conducted as the research objects.Bone defect length after tumor resection was(17.3±4.2)cm,in order to coinside with the peroneal vessels in the other side, fibulas with peroneal vessels from both sides should be cut down.Dual fibula medial periosteal was stripped from the central longitudinal incision to the bone crest,folding fibula two-stage to make the front sides face to face, and then fixed the ends.The peroneal vascular was looped on one side of graft to form a U shape. The vessels out of damage region was dissected, and was inserted fibula between the ends of fracture, as the case wire or screws may be used.The peroneal vessels had to coinside with those in damage region,and imaging assessment should be taken to evaluate the healing of bone joints after surgery,at the same time,assessing postoperative function by functional scores of Bone Cancer Society of the United States was also neccessary, finally vascular anastomosis through the bleeding condition of the grafts were detected. Results All patients were followed up for 5-8 years,the bone healed 1 year later, and the transplanted bone marrow cavity got recanalization 5 years later,at the same time, there was no tumorigenesis in the double fibula, and x-ray showed the good healing. All bones turned to be normal ones without nonunion, infection and other complications. Final follow-up score of lower limbs was 91.2%. Conclusion It is effective and feasible to use a combination of double fibula to repair lower extremity long bone defects caused by large bone fibrous dysplasia in the periosteum. Key words: Fibrous dysplasia of bone; Bone defect; Bone transplantation operation

Exploratory study of ultra-high performance fiber reinforced concrete tunnel lining segments with varying steel fiber lengths and dosages

Ultra-high performance fiber-reinforced concrete (UHPFRC) is an emerging material exhibiting superior mechanical and durability properties. However, its application in precast concrete tunnel linings is lagging due to lack of experimental data and adequate design provisions. This study is a preliminary investigation of UHPFRC tunnel lining segments incorporating various steel fiber lengths and dosages. The mechanical performance of UHPFRC tunnel lining segments was investigated. Flexural and edge-point load tests were conducted on 1/3-scale UHPFRC tunnel lining segments to evaluate its bending and thrust load resistance. The main studied variables were the steel fiber lengths and dosages. Results showed that UHPFRC tunnel lining segments incorporating shorter steel fibers exhibited higher cracking and peak loads compared to that of similar segments made with longer fibers. Furthermore, the shorter fibers enhanced the strain hardening phase, leading to more stable multiple micro-cracks and higher resistance to growth of macro-cracks. Conversely, longer steel fibers better improved the post-peak strain softening of the lining segments, achieving more ductile failure. The load carrying capacity of UHPFRC lining segments linearly increased with higher fiber dosage and followed the rule of mixtures. Moreover, steel fibers enhanced the cracking behavior under both thrust load and concentrated load compared to that of segments without fibers.

Influence of fiber length on the tensile behavior of fiber metal laminates with discontinuous reinforcement

In this paper, the influence of fiber length on the tensile behavior of fiber metal laminate, which is fabricated with unidirectionally arrayed chopped strand plies and aluminum sheets and named as unidirectionally arrayed chopped strand/aluminum laminate, was investigated based on finite element analysis and experiment. The unidirectionally arrayed chopped strand ply is made by introducing slits into carbon fiber reinforced plastic prepreg where continuous fibers are arrayed unidirectionally. The fiber length is one of the most fundamental factors in tailoring the unidirectionally arrayed chopped strand/aluminum laminate to achieve the desired mechanic behaviors for specific applications. With longer fiber length, the mechanical behaviors of the bulk laminate should be more favorable, while the formability would be better with short fiber. Two-dimensional finite element models, with intra-laminar cohesive zone elements inserted into the slits of unidirectionally arrayed chopped strand plies and inter-laminar cohesive zone elements inserted into the all interfaces of unidirectionally arrayed chopped strand/aluminum laminate, respectively, were developed for the analysis of unidirectionally arrayed chopped strand/aluminum laminates with different fiber lengths under tension. Typical numerical results were validated by experimental results, which confirm that the tensile behaviors of the unidirectionally arrayed chopped strand/aluminum laminates with various different fiber lengths can be well predicted by present numerical modeling method.

Finite-length effects on dynamical behavior of rod-like particles in wall-bounded turbulent flow

Combined Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) measurements have been performed in dilute suspensions of rod-like particles in wall turbulence. PIV results for the turbulence field in the water table flow apparatus compared favorably with data from Direct Numerical Simulations (DNS) of channel flow turbulence and the universality of near-wall turbulence justified comparisons with DNS of fiber-laden channel flow. In order to examine any shape effects on the dynamical behavior of elongated particles in wall-bounded turbulent flow, fibers with three different lengths but the same diameter were used. In the logarithmic part of the wall-layer, the translational fiber velocity was practically unaffected by the fiber length l. In the buffer layer, however, the fiber dynamics turned out to be severely constrained by the distance z to the wall. The short fibers accumulated preferentially in low-speed areas and adhered to the local fluid speed. The longer fibers (l/z>1) exhibited a bi-modal probability distribution for the fiber velocity, which reflected an almost equal likelihood for a long fiber to reside in an ejection or in a sweep. It was also observed that in the buffer region, high-speed long fibers were almost randomly oriented whereas for all size cases the slowly moving fibers preferentially oriented in the streamwise direction. These phenomena have not been observed in DNS studies of fiber suspension flows and suggested l/z to be an essential parameter in a new generation of wall-collision models to be used in numerical studies.

Effect of herbicides on yield and quality of straw and homomorphic fibre in flax (Linum usitatissimum L.)

Fibre flax (Linum usitatissimum L.) is a very poor competitor with weeds, and to obtain acceptable yields, weeds should be effectively controlled. Very little information is available on the tolerance of flax to herbicide applications. Types of applied herbicides determine not only the yield of flax but can also affect yield of fibre, its quality and may affect processes (physical, chemical and enzymatic) used in the refining of homomorphic fibres to increase their thinness and divisibility. Presented basic field research was carried out in the years 2011–2012. In the studies the impact of three herbicides (with a.i. linuron, bentazon and chlorsulfuron) was examined on the control of weeds, course of vegetation and yield and quality of flax homomorphic fibre. The applied herbicides had a significant impact on the weed control, the length of the vegetation, straw yield, the percentage of fibre in the straw, weight and length of the fibre and its thinness and divisibility. The lowest number and mass of weeds and the highest flax straw yield and fibre quality was obtained after chlorsulfuron application. Bentazon, despite its high herbicidal effectiveness, reduced both the amount and quality of fibre yield when compared to chlorsulfuron, due to its phytotoxic effect on flax. Pre-emergence linuron application resulted in the longest fibres and highest fibre content in flax straw.

Analytical Analysis of In-Band Crosstalk, Out-of-Band Crosstalk and GVD-Based Power Penalties in DWDM and TDM/DWDM-PONS

In addition to the ever-increasing demand for broader bandwidth per user, which results from the continuous development of new bandwidth-hungry services and applications, the consequent upgrade from the currently deployed Time-Division Multiplexing Passive Optical Networks (TDM-PONs) to Next-Generation Optical Access Networks (NG-OANs) has become inevitable. Different architectures for creating a NG-OAN have been proposed in the literature. Among those architectures, the DWDM and TDM/DWDM-Based OANs are very promising candidates. They were mainly proposed to exploit the large wavelength counts available in the fibre (its virtual unlimited bandwidth) to achieve a significant increase in the system capacity. Moreover, they allow coexistence in an open access environment among different network operators. In this study, we first analyze the impact of in-band crosstalk, out-of-band crosstalk to evaluate the performance of the Arrayed Waveguide Grating (AWG). The reason to focus on the AWG is due to this optical device is used almost in all DWDM and TDM/WDM-PONs. We then turn our attention to analyze the impact of group velocity dispersion GVD to estimate the maximum allowable bit rate for optical transmission without the need for using a Dispersion Management Technique (DMT) and/or a Forward Error Correction Technique (FECT). The analysis was performed using Matlab software (The Math works, Inc., Natick, MA, USA) and confirms that the in-band crosstalk has a stronger effect than the out-of-band crosstalk because its noise floor is reached at a lower crosstalk noise and with fewer crosstalk components. The in-band crosstalk noise should be kept below -37 dB and -34 dB to maintain a power penalty of less than 1 dB if 15 and 7 in-band crosstalk components are considered, respectively. The out-of-band crosstalk noise should be kept below -20.3 dB and -17.18 dB to maintain a power penalty of less than 1 dB if 240 and 56 out-of-band crosstalk components are considered, respectively. It was observed that the GVD noise floor is reached at a shorter fiber length as the bit rate increases and it was confirmed that a significant improvement in which the GVD noise floor is reached at longer fiber can be achieved if an externally modulated, small spectral-width source is used when a bit rate of 622 Mbps, 1 Gps, or 2.5 Gbps is used. However, a dispersion management technique becomes necessary if the bit rate increases to 10 Gbps or more.