Length Of Sheets Research Articles

Visualization studies of the spray from swirl injectors under elevated ambient pressure

This paper presents the results of a visualization study on spray formed by swirl injectors with different geometries under elevated ambient pressure. A spray test facility with an ambient pressure chamber was constructed, and sprays were recorded using a high-speed camera. The parameters of the spray characteristics, e.g. the spray cone angle and breakup length of liquid sheet, were measured, and the effects of the ambient pressure and injector geometrical parameters on the spray were obtained. Experimental results indicated that when other parameters in the swirl injector remained constant, the increase of ambient pressure caused a decrease in the spray cone angle and the breakup length of liquid sheets. However, the mass flow rates remained nearly constant. An increase in nozzle diameter increased the spray cone angle, and the variation of breakup length according to nozzle diameter was somewhat irregular. The increase in the diameter of the tangential inlet reduced the spray cone angle; the breakup length scarcely varied.

Information for consent: Too long and too hard to read

The length of participant information sheets (ISs) for research and difficulties in their comprehension have been a cause of increasing concern. We aimed to examine the information sheets in research proposals submitted to an Australian HREC in one year, comparing the results with national recommendations and published data. Information sheets in all 86 research submissions were analysed using available software. The work of Flesch was used for Reading Ease or Readability and that of Flesch and Kincaid for the level of education required for comprehension, the Reading Grade Level. The mean length of 86 information sheets was 3110 words; many had more than 5000 words. Using the Flesch scale of 0 to 100, with 0 meaning most difficult and 100 very easy to read, the mean readability level was 47. The mean length of education needed to easily grasp the information was 11.6 years, equivalent to senior secondary school. Information sheets in research projects submitted to an HREC were often too long to be read in a reasonable time and too difficult to be easily understood. Recommended standards for information sheets were infrequently met.

Relationships between interfacial shear stresses and moment capacities of RC beams strengthened with various types of FRP sheets

The objective of this study is to evaluate moment capacity based on interfacial shear stress of reinforced concrete (RC) beams strengthened with various types of fiber reinforced polymer (FRP) sheets. Toward this goal, RC beams strengthened with taper layered carbon FRP (CFRP) and hybrid FRP sheets were fabricated and subjected to four-point loading. From the experiments, interfacial shear stresses along the length of the CFRP sheets and maximum moments were obtained. The experimental results clearly showed that interfacial shear stress had significant influence on maximum moment of RC beams strengthened with FRP sheets. The relationship between interfacial shear stress and maximum moment capacity was considered for the moment capacity of RC beams with taper layered FRP sheets, and the numerical results showed good agreements with experimental results. In addition, finite element (FE) analytical studies were performed and the results validated relationship between interfacial shear stresses and maximum moment capacities.

Sonication-free dispersion of large-area graphene oxide sheets using internal pressure from release of intercalated carbon dioxide

A new concept to disperse graphene sheets without sonication, significant size reduction, and any further removal of intercalating materials, is demonstrated using ejection pressure of CO2 gas captured by water molecules dissolved in the interlayer of graphene and the ice structure surrounding it. After graphene oxide (GO) layers are swelled with water molecules, CO2 gas is dissolved in the swelled interlayer of GO. The CO2 gas within the GO layers is well maintained by the transformation of excess water molecules outside of interlayer to solid ice at low temperature (around −30°C). The resulting CO2-incorporating GOs are well dispersed in various solvents by the ejection pressure of stored CO2 without sonication, and without additional treatment for removal of the intercalating material as surrounding ices spontaneously melt. We show that the lateral length of these well-dispersed GO sheets is 10 times larger than that of GO sheets obtained by the conventional sonication method.

Fabrication of Nb2O5 nanosheets for high-rate lithium ion storage applications.

Nb2O5 nanosheets are successfully synthesized through a facile hydrothermal reaction and followed heating treatment in air. The structural characterization reveals that the thickness of these sheets is around 50 nm and the length of sheets is 500 ~ 800 nm. Such a unique two dimensional structure enables the nanosheet electrode with superior performance during the charge-discharge process, such as high specific capacity (~184 mAh·g−1) and rate capability. Even at a current density of 1 A·g−1, the nanosheet electrode still exhibits a specific capacity of ~90 mAh·g−1. These results suggest the Nb2O5 nanosheet is a promising candidate for high-rate lithium ion storage applications.

Numerous single‐layer graphene sheets prepared from natural graphite by non‐chemical liquid‐phase exfoliation

A simple method was used to produce a high concentration of single-layer graphene sheets in a single organic solvent system, without using any surfactants. In this experiment, the concentration of single-layer graphene sheets dispersed in solution increased as the sonication time increased, but damage occurred after performing sonication for 120 min. The concentration of single-layer graphene sheets was 0.915 mg/ml after sonication for 60 min. According to a transmission electron microscope image, the length of the single-layer graphene sheets was ∼2–3 μm, and the width was 0.5–1 μm. The perfect single-layer graphene sheets and the defective single-layer graphene sheets were distinguished using selected-area electron diffraction. X-ray diffraction determined that the two-theta angle of the numerous single-layer graphene sheets on a (002) plane was 25.57°, but the ‘one layer’ graphene sheets produced no peak along the (002) plane. According to the Raman spectra, the ratio of ID /IG was 0.3, which indicated that the graphene sheets contained few defects.

Morfogênese e fluxo de tecidos em capim Tanzânia sob diferentes ofertas de forragem

This study was conducted to identify effective strategies for grazing managing of Panicum maximum Jacq cv. Tanzania, under continuous stocking with variable stocking rate, based on assessments of their morphogenetic and structural characteristics. Four forage allowances: 3, 7, 11, and 15% BW were studied. A randomized block design, with three replicates was used, with split plot, where FA 4 as main plots and subplots were established cages. The number of basal tillers per cage protected and unprotected, both remaining as the new, decreased with FA. The unprotected tillers had higher numbers than cage protected. The weight of tillers and roots showed curvilinear response function in the FA. There was no effect of period at tillering (P> 0.05) of Tanzania grass. The total length of sheets, protected or not by exclusion cage and ligule height of tillers per cage had unprotected quadratic fit function OF. The ligule height protected tillers showed linear response function in the OF. The total number of leaves, expanded and expanding, tiller protected or not by exclusion cage, showed no differences between the FA and cage exclusion. The use of forage allowance of 11% of body weight for tanzania grass managed under continuous grazing and variable stocking rate, seems to be more sustainable.

Breakup characteristics of power-law liquid sheets formed by two impinging jets

The breakup characteristics of the shear-thinning power-law liquid sheets formed by two impinging jets have been investigated with the shadowgraph technique. This paper focuses on the effects of spray parameters (jet velocity), physical parameters (viscosity) and geometry parameters (impinging angle and nozzle cross-sectional shape) on the breakup behaviors of liquid sheets. The breakup mode, sheet length and expansion angle of the sheet are extracted from the spray images obtained by a high speed camera. Impinging angle and Weber number play the similar roles in promoting the breakup of liquid sheets. With the increase of jet velocity, five different breakup modes are observed and the expansion angle increases consistently after the closed-rim mode while the sheet length first increases and then decreases. But there exists a concave consisting of a fierce drop and a second rising process on the sheet length curve for the fluid with smaller viscosity. Different nozzle cross-sectional shapes emphasize significant effects on the sheet length and expansion angle of liquid sheets. At a fixed Weber number, the liquid sheet with greater viscosity has a greater sheet length and a smaller expansion angle due to the damping effect of viscosity.

Folding of multi-layer graphene sheets induced by van der Waals interaction

Graphene sheets are extremely flexible, and thus small forces, such as van der Waals interaction, can induce significant out-of-plane deformation, such as folding. Folded graphene sheets show racket shaped edges, which can significantly affect the electrical properties of graphene. In this paper, we present combined theoretical and computational studies to reveal the folding behavior of multi-layer graphene sheets. A nonlinear theoretical model is established to determine the critical length of multilayer graphene sheets for metastable and stable folding, and to accurately predict the shapes of folded edges. These results all show good agreement with those obtained by molecular dynamics simulations.

Experimental study on strengthening of R.C beam using glass fibre reinforced composite

This paper reports the influence of number of layers and length of GFRP sheets wrapped onto RCC beams for strengthening. Twelve beams of size <TEX>$700</TEX><TEX>mm{\times}150mm{\times}150mm$</TEX> were cast and tested. Two beams without GFRP and ten beams wrapped in different lay-up patterns with one and two layers of GFRP sheets was subjected to three point loading test and ultrasonic pulse velocity test. Initial crack load, ultimate failure load and types of failure have been observed and noted. Experimental results indicate a significant increase in initial and ultimate load carrying capacity of GFRP wrapped beams compared to unwrapped beams. The failed control specimen was retrofitted using U wrap scheme and tested under three point loading.

Comparison of modeling methods and parametric study for a piezoelectric wind energy harvester

Harvesting flow energy by exploiting transverse galloping of a bluff body attached to a piezoelectric cantilever is a prospective method to power wireless sensing systems. In order to better understand the electroaeroelastic behavior and further improve the galloping piezoelectric energy harvester (GPEH), an effective analytical model is required, which needs to incorporate both the electromechanical coupling and the aerodynamic force. Available electromechanical models for the GPEH include the lumped parameter single-degree-of-freedom (SDOF) model, the approximated distributed parameter model based on Rayleigh–Ritz discretization, and the distributed parameter model with Euler–Bernoulli beam representation. Each modeling method has its own advantages. The corresponding aerodynamic models are formulated using quasi-steady hypothesis (QSH). In this paper, the SDOF model, the Euler–Bernoulli distributed parameter model using single mode and the Euler–Bernoulli distributed parameter model using multi-modes are compared and validated with experimental results. Based on the comparison and validation, the most effective model is employed for the subsequent parametric study. The effects of load resistance, wind exposure area of the bluff body, mass of the bluff body and length of the piezoelectric sheets on the power output are investigated. These simulations can be exploited for designing and optimizing GPEHs for better performance.

The surface charge of regenerated cellulose fibres

In this paper the influence of charged species on the sheet strength of viscose fibres was investigated. Four samples of chemical modified viscose fibres, as well as a reference fibre were studied. The swelling of these viscose fibres and the breaking length of hand sheets have been determined. Comparing the results, the influence of both, swelling and surface charge on the bonding force, is evident. The allocation of the charges, induced by cationic starch and Carboxmethylcellulose, has been analyzed by Titration, attenuated total reflection spectroscopy (ATR) and X-ray photoelectron spectroscopy (XPS). Titration was used to make a first estimation of the charge distribution within the fibre. Using ATR and XPS, more detailed information about the surface charge has been achieved. All measurement methods showed a significant amount of charge on the fibre surface.

Effective bond length of FRP-to-concrete adhesively-bonded joints: Experimental evaluation of existing models

Bond behavior of adhesively-bonded fiber reinforced polymers (FRPs) to concrete substrate has been investigated by many researchers worldwide. An interesting aspect of FRP-to-concrete bond behavior is that there exists an effective bond length beyond which an extension of the bond length cannot increase the ultimate capacity of the joint. Effective bond length of FRP composites, in fact, is an important part of all strengthening calculations, and conservative design guideline predictions can lead to waste of composite materials in strengthening projects. Consequently, the main intention of the current study is to evaluate the accuracy of existing guideline models of effective bond length by means of single-shear bond tests. To do so, carbon FRP (CFRP) sheets with a wide range of bond length from 20 to 250mm, were adhered to 22 concrete prisms using externally bonded reinforcement (EBR) technique. The specimens were then subjected to single-shear test and debonding loads as well as the effective bond length of the CFRP sheets were determined. Moreover, an image based technique, i.e. particle image velocimetry (PIV) was used to verify the estimated effective bond length by analyzing strain distribution along the CFRP strips during loading process. Experimental results of the current study show that fib Bulletin 14 model overestimates debonding loads and effective bond length. The model adopted by ACI 440.2R-08 also overestimates effective bond length while accurately predicts debonding loads. Appropriate calibration factors were introduced to modify the existing models for CFRP sheets.

Effect of the combination of biobeating and NFC on the physico-mechanical properties of paper

The combined effect of enzymatic treatment (biobeating) and NFC addition on the mechanical and physical properties of a papermaking pulp suspension was investigated. The influence of pH, consistency of pulp and reaction time of the enzyme on the pulp strength was evaluated by measuring the breaking length of paper sheets made thereof. The results showed that the enzymatic treatment improved mechanical properties of fibres without modifying drainability. After biobeating, NFC was added to the enzyme-treated pulps. Mechanical properties were enhanced, obtaining length at break values similar to those observed in commercial printing/writing paper. Opacity remained constant, whereas porosity was gradually reduced as more amount of NFC was added. The presence of NFC also reduced drainability, although it remained at suitable levels for the papermaking industry. The results suggest that the combination of biobeating and NFC addition can be considered as an alternative to mechanical beating.

Microscopic investigation of soot and ash particulate matter derived from biofuel and diesel: implications for the reactivity of soot

Investigation of soot and ash particulate matter deposited in diesel particulate filters (DPFs) operating with biofuel (B100) and diesel (pure diesel: B0 and diesel80/biofuel20 blend: B20) by means of optical microscopy, scanning electron microscopy, and high resolution transmission electron microscopy (HRTEM) reveals the following: the rapeseed methyl ester biofuel used for this study contributes to ash production, mainly of Ca–S– and P-bearing compounds ranging in size between 50 and 300 nm. Smaller ash particles are less common and build aggregates. Ash is deposited on the inlet DPF surface, the inlet channel walls, and in B100-DPF at the plugged ends of inlet channels. The presence of Fe–Cr–Ni fragments, down to tens of nanometers in size within the ash is attributed to engine wear. Pt particles (50–400 nm large) within the ash indicate that the diesel oxidation catalyst (DOC) upstream of the DPF shows aging effects. Radial cracks on the coating layer of the DOC confirm this assumption. The B100-DPF contains significantly less soot than B20 and B0. Based on the generally accepted view that soot reactivity correlates with the nanostructure of its primary particles, the length and curvature of graphene sheets from biofuel- and diesel-derived soot were measured and computed on the basis of HRTEM images. The results show that biofuel-derived soot can be more easily oxidized than diesel soot, not only during early formation but also during and after considerable particle growth. Differences in the graphene sheet separation distance, degree of crystalline order and size of primary soot particles between the two fuel types are in line with this inference.

Characterization of Fluoropolymer Nanofiber Sheets Fabricated by CO2Laser Drawing without Solvents

Nanofibers of tetrafluoroethylene-perfluoroalkyl vinylether (PFA) copolymer were prepared by irradiating PFA fibers with a CO2 laser under supersonic velocities. This is the only method to make PFA nanofibers without the use of solvents, because for the majority of methods for preparing nanofibers, they must be dissolved in a solvent and PFA fibers cannot be dissolved in most solvents, except special fluorinating reagents. The average fiber diameter of PFA nanofibers was approximately 273 nm. As a result, we developed a CO2 laser supersonic multidrawing (CLSMD) in a new way to produce PFA nanofibers in large quantities. CLSMD can make nanofibers continually in a wide area. The length, width, and thickness of pileup nanofiber sheets are 50 cm, 17 cm, and 70 μm, respectively. It was observed that nanofiber sheets have a higher melting point and degree of crystallinity than microfibers by differential scanning calorimetry (DSC) measurements and have larger crystallite size realized by wide-angle X-ray diffraction (WAXD) measurements. Moreover, it was considered that the interior of nanofiber sheets have oriented structurally and the strength of nanofiber sheets was higher than that of microfibers. Nanoparticles were evolved to the surface of nanofiber sheets by annealing.

Modelling the liquid-water vein system within polar ice sheets as a potential microbial habitat

Based on the fundamental and distinctive physical properties of polycrystalline ice Ih, the chemical and temperature profiles within the polar ice sheets, and the observed selective partitioning of bacteria into liquid water filled veins in the ice, we consider the possibility that microbial life could survive and be sustained within glacial systems. Here, we present a set of modelled vertical profiles of vein diameter, vein chemical concentration, and vein water volume variability across a range of polar ice sheets using their ice core chemical profiles. A sensitivity analysis of VeinsInIce1.0, the numerical model used in this study shows that the ice grain size and the local borehole temperature are the most significant factors that influence the intergranular liquid vein size and the amount of freeze-concentrated impurities partitioned into the veins respectively. Model results estimate the concentration and characteristics of the chemical broth in the veins to be a potential extremophilic microbial medium. The vein sizes are estimated to vary between 0.3μm to 8μm across the vertical length of many polar ice sheets and they may contain up to 2μL of liquid water per litre of solid ice. The results suggest that these veins in polar ice sheets could accommodate populations of psychrophilic and hyperacidophilic ultra-small bacteria and in some regions even support the habitation of unicellular eukaryotes. This highlights the importance of understanding the potential impact of englacial microbial metabolism on polar ice core chemical profiles and provides a model for similar extreme habitats elsewhere in the universe.

Children's participation in clinical research: factors influencing parental consent

Background An important obstacle when undertaking clinical research in children is the consent procedure. Understanding the factors influencing this process is vital in improving children9s involvement in clinical research. Objective To report the rates and causes for recruitment refusal into two studies of childhood pneumonia and empyema and investigate the underlying factors contributing to refusal. Methods Two paediatric respiratory studies investigating childhood pneumonia and empyema and requiring informed consent were carried out at the same site. During the period from April 2010 to March 2011, the number of eligible children who gave or refused consent for each study was documented. Each research team included a paediatric research nurse and paediatric research registrar (doctor). Information was collected prospectively on each consent refusal. Rates of refusal by role of person taking consent, severity of illness and reason for refusal were then analysed. Results A total of 116 children were eligible for enrolment into pneumonia study and 28 into empyema study, giving 144 consent procedures. Ten (7%) parents refused the consent. The rate of refusal did not differ between medical and nursing staff. Eighty percent of the children who were not enrolled had severe disease. Refusals were linked with not wanting the child to undergo further investigations, research delaying discharge, and anxiety regarding written consent and length of information sheets. Conclusion Consent refusal was not related to the role of the person seeking consent. Severity of child9s illness appears to determine parent9s decision regarding participation in clinical research.

Variation in Catalytic Activity of Carbon Black during Methane Decomposition: Active Site Estimations from Surface Structural Characteristics

The variation in the catalytic activity of carbon black (CB) during methane decomposition was investigated by considering the number of active sites of CB. We demonstrated that the activity variation could be well estimated by assuming the edge length of graphitic sheets evolving from the CB surface. The results suggested that the activity variation originated from surface structural changes due to carbon deposition.

Performance Evaluation of RC Beams Strengthened with an Externally Bonded FRP System under Simulated Vehicle Loads

Carbon fiber-reinforced polymer (CFRP) sheets can be used to strengthen existing RC bridge girders/decks. The objective of this study is to investigate whether transient vehicle loads present during the installation of CFRP influence the bond performance between the CFRP and the concrete substrate and, therefore, the consequent strengthening effect. A total of eight RC beams were tested. Two were unstrengthened reference beams, five were strengthened with CFRP sheets while subject to transient loads, and the final beam was strengthened with CFRP sheets while subject to only a sustained static load. The test parameters included the amplitude of the transient load, the anchorage length of the CFRP sheets, and the reinforcing/strengthening ratio. The transient loads were continued for 2 days (during CFRP cure) before all five CFRP-strengthened RC beams were tested to failure in four-point flexure. The test results were compared with those of the reference beams and the one strengthened under a sustained load. It was shown that a 1-Hz sinusoidal transient load varying between 30 and 50% of the ultimate capacity of the unstrengthened beam during the installation and curing of the CFRP sheets does not affect the structural performance of CFRP-strengthened RC beams. This result demonstrates the applicability of the fiber-reinforced polymer (FRP) strengthening technique for bridge girders that are subjected to continuous vehicle loads.