Radial Faces Research Articles

Experimental analysis of the thermo-hydro-mechanical (THM) coupling in freezing vertical shafts of unsaturated sandy soil

The evolutionary mechanism of frozen soil involves complex dynamic coupling among temperature, moisture and the stress field. However, existing research has struggled to adequately describe the interplay between these factors. To address this, we independently designed and developed a multifunctional loading system appropriate for geotechnical engineering experimentation and a corresponding loading technology. Using a model of vertical shaft freezing, we studied the spatiotemporal evolution of thermo-hydro-mechanical (THM) multi-field coupling. The research findings indicate that, compared to the freezing interface, the main section experiences not only more intense variations in the temperature field but also heightened activity in terms of in-situ freezing and moisture migration. Both the radial and circumferential characteristic faces exhibit wave-like variations in moisture gradient evolution. The circumferential face features a critical gradient at 3.8 m−1, whereas the moisture gradient curve of the radial face undergoes temporal elongation at the peak, resulting in no discernible extremities. Each characteristic position of the frost heave force growth undergoes three distinct phases: incubation, rapid increase and stabilisation. During the same phases, the response times for the growth of frost heave forces on the radial characteristic face are roughly equivalent. However, when moving outward along the equivalent freezing radius, the response time on the circumferential face becomes progressively delayed.

Связь механических свойств анизотропных материалов с их теплофизическими характеристиками на примере древесины сосны

The paper discusses experimentally found relation between mechanical an thermal physical properties of anisotropic materials observed at the pine wood (Pínus sylvéstris L). Hardness and main components of temperature diffusivity tensor measured at the normal to the fibers, tangential and radial faces of the pine wood sample having various moisture content can be linked with linear relations. It renders possible to make express estimation of anisotropic materials mechanical properties typically requiring labor and material extensive destructive testing by means of measurement of its thermal properties using dynamic thermography.

Experimental Parameters Influence the Observed Antimicrobial Response of Oak Wood (Quercus petraea).

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p < 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

Influence of anatomy on the adhesion performance of four wood species

The aim of this study was to evaluate the influence of anatomical characteristics on the adhesion performance of Vatairea sp., Paulownia sp., Aspidosperma populifolium and Tectona grandis wood. Specimens for anatomical, physical and mechanical analyzes were produced from tangentially oriented boards. The treatments were joint glued from pieces of the same anatomical orientation (radial and tangential), evaluated for shear strength and glue line failure. The Vatairea sp wood had the highest specific gravity (0.74 g cm-3) and the Paulownia sp (0.34 g cm-3) wood was smaller. Aspidosperma populifolium species showed the highest shear strength in the glue line in the tangential and radial faces. The anatomical variables with higher influence on the wood adhesion process were pith ray cells and especially fibers that exhibit the greatest correlation with the shear strength of the glue line.

Production of Joints Of Eucalyptus Sp. to Obtain Edge Glued Panels

ABSTRACT This research aimed at evaluating the quality of bonded joints of Eucalyptus wood by using different faces and adhesives to produce EGP (Edge Glued Panels). Glue line shear specimens were obtained from bonded joints glued with PVAc (Polyvinyl Acetate) and EPI (Emulsion Polymer Isocyanate) adhesives, using pieces oriented with tangential, radial and intermediary faces, as well as the combination between them. The specimens were submitted to two pretreatments in order to simulate the use of joints in dry and wet environments. For shear tests, 12 treatments were obtained. The results indicated that the use of tangential x tangential and tangential x intermediary bonding faces and EPI adhesive presented better glue line shear strength for EGP in dry and wet pretreatments, respectively. The joints bonded in the radial x radial direction presented statistically inferior values when compared to the other treatments.

Investigations into Helix Slow-Wave Structure Assisted by Double-Negative Metamaterial

A helical slow-wave structure consisting of a metallic helix supported by double-negative metamaterial (DNG-MTM) rods, symmetrically arranged around the helix, in a metal envelope was analyzed, considering the frequency-dependent permeability and the permittivity of the DNG-MTM following Lorentz and Drude models. The analysis was validated against the 3-D electromagnetic simulation using CST Studio and was extended for studying the effects of the DNG-MTM parameters on the dispersion and interaction impedance of the structure. Tunability of the structure over multiple-frequency bands was also demonstrated. The possible means of metal MTM layering of the radial faces of the discrete support rods were suggested in a more realistic structure configuration. The structure exhibited a high value of interaction impedance as compared to its traditional counterpart, promising enhanced device efficiency and miniaturization. The structure has potential applications in backward-wave amplifiers and backward-wave oscillators.

Disentangling the origins of torque enhancement through wall roughness in Taylor–Couette turbulence

Direct numerical simulations (DNS) are performed to analyse the global transport properties of turbulent Taylor–Couette flow with inner rough wall up to Taylor number$Ta=10^{10}$. The dimensionless torque $Nu_{\unicode[STIX]{x1D714}}$ shows an effective scaling of $Nu_{\unicode[STIX]{x1D714}}\propto Ta^{0.42\pm 0.01}$, which is steeper than the ultimate regime effective scaling $Nu_{\unicode[STIX]{x1D714}}\propto Ta^{0.38}$ seen for smooth inner and outer walls. It is found that at the inner rough wall, the dominant contribution to the torque comes from the pressure forces on the radial faces of the rough elements; while viscous shear stresses on the rough surfaces contribute little to $Nu_{\unicode[STIX]{x1D714}}$. Thus, the log layer close to the rough wall depends on the roughness length scale, rather than on the viscous length scale. We then separate the torque contributed from the smooth inner wall and the rough outer wall. It is found that the smooth wall torque scaling follows $Nu_{s}\propto Ta_{s}^{0.38\pm 0.01}$, in excellent agreement with the case where both walls are smooth. In contrast, the rough wall torque scaling follows $Nu_{r}\propto Ta_{r}^{0.47\pm 0.03}$, very close to the pure ultimate regime scaling $Nu_{\unicode[STIX]{x1D714}}\propto Ta^{1/2}$. The energy dissipation rate at the wall of an inner rough cylinder decreases significantly as a consequence of the wall shear stress reduction caused by the flow separation at the rough elements. On the other hand, the latter shed vortices in the bulk that are transported towards the outer cylinder and dissipated. Compared to the purely smooth case, the inner wall roughness renders the system more bulk dominated and thus increases the effective scaling exponent.

Synthesis of Nonequilibrium Supramolecular Peptide Polymers on a Microfluidic Platform.

The self-assembly of peptides and peptide mimetics into supramolecular polymers has been established in recent years as a route to biocompatible nanomaterials with novel mechanical, optical, and electronic properties. The morphologies of the resulting polymers are usually dictated by the strengths as well as lifetimes of the noncovalent bonds that lead to the formation of the structures. Together with an often incomplete understanding of the assembly mechanisms, these factors limit the control over the formation of polymers with tailored structures. Here, we have developed a microfluidic flow reactor to measure growth rates directly and accurately on the axial and radial faces of crystalline peptide supramolecular polymers. We show that the structures grow through two-dimensional nucleation mechanisms, with rates that depend exponentially on the concentration of soluble peptide. Using these mechanistic insights into the growth behavior of the axial and radial faces, we have been able to tune the aspect ratio of populations of dipeptide assemblies. These results demonstrate a general strategy to control kinetically self-assembly beyond thermodynamic products governed by the intrinsic properties of the building blocks in order to attain the required morphology and function.

Impacts of fiber orientation and milling on observed crystallinity in jack pine

Influences of fiber orientation and milling on wood cellulose crystallinity were studied using jack pine wood. The fiber orientation effects were measured by sampling rectangular wood blocks in radial, tangential, and cross-sectional orientations. The influence of milling was studied by analyzing the unsieved and sieved milled wood fractions (all <1,000 μm). Fiber orientation effect was manifested in both X-ray and Raman measurements and was dependent upon the orientation of the sampled wood blocks. In Raman, the observed crystallinity was similar between the blocks sampled on the tangential and the radial faces. However, the estimated values were 5.5 % lower compared to that measured in a powdered sample pellet. Moreover, in these sampling modes, the orientation of the block with respect to the direction of the electric vector of the laser made a difference only for the tangential mode of sampling. When a wood block was sampled on the cross-sectional face, the observed Raman crystallinity was 3.9 % higher from that of the pellet. The observed crystallinity did not significantly differ with change in sample orientation with respect to the electric vector direction. In contrast, the Segal-WAXS study of the blocks indicated that compared to the pellet, the estimated crystallinities in the radial, tangential, and cross-sectional sampling modes were 5, 2, and 11 % lower, respectively. This suggested that the radial and the tangential faces of the blocks can be used to estimate the crystallinity of wood. With regard to the effect of milling on Raman and Segal-WAXS estimates, the wood crystallinity did not depend upon the particle sizes of the fractionated samples and was similar to that of the original unfractionated ground wood.

A development of the HEXNEM nodal expansion method

In this paper a development of the HEXNEM nodal expansion methods is presented, together with a program implementation and results from comparisons with benchmark problem solutions. The new development consists in the introduction of tangentially weighted exponential basis functions and continuity and boundary conditions for the tangential moments of the partial current in a way similar to that employed in some methods of the AFEN family. This is aimed at a better accounting for the flux variation along the radial node faces which for the large WWER-1000 assemblies can be a significant source of error. The test problem results presented in the paper indicate that an improved accuracy for WWER-1000 is achieved as compared with the HEXNEM2 method.

Estimating mechanical properties and specific gravity for five-year-old Eucalyptus tereticornis having broad moisture content range by NIR spectroscopy

Abstract Near infrared spectroscopy coupled with multivariate data analysis has been used to predict the specific gravity, modulus of rupture, modulus of elasticity, and fiber stress at elastic limit in bending tests on radial and tangential strip wood samples obtained from five-year-old Eucalyptus tereticornis. Moisture content of samples was 6–21% for bending test and 7–16% for specific gravity. Partial least squares regression calibrations were developed for each wood property. Calibrations had good relationships between values measured in laboratory and NIR predicted values obtained from small clear samples. The coefficient of determination (R2) for calibration ranged from 0.76 to 0.83 and for prediction (Rp 2) it was between 0.58 and 0.77. Both radial and tangential faces are equally suited for calibration (for radial face R2 was 0.77–0.83 and for tangential it was 0.76–0.83). Standard errors of predictions were slightly higher compared to standard error of calibration.

Estimation of the mechanical properties of wood from Eucalyptus urophylla using near infrared spectroscopy

Mechanical properties studies of wood usually involve destructive wood assessments, with time-consuming tests that use large amounts of resource (wood). Although this is not a limiting factor, it could be attenuated by the use of a nondestructive technique known as near infrared spectroscopy (NIRS). This technique has been applied to evaluate compounds containing C-H, N-H, S-H or O-H bonds, and involves quick analyses and can be applied to process control tasks. The objective of this work is to use the NIRS technique to obtain calibrations for mechanical properties of Eucalyptus sp. wood. A natural E. urophylla hybrid at age 7 was used as obtained from V&amp;M Florestal crops. Spectra were measured directly in solid wood (radial, tangential and transverse faces) and in ground wood, in diffuse reflectance mode, using a Bruker spectrometer in the 800 to 1,500 nm range. The NIRS technique proved suitable to estimate modulus of elasticity in solid wood, with values r=0.91 and RPD=2.6, and in ground wood, with values r=0.87 and RPD=2.0. Modulus of rupture and compressive strength presented r values below 0.9. First and second derivative pretreatments provided a slight increase in correlation values for the properties in question. Calibrations for different plank faces did not present a defined variation pattern. Solid wood and ground wood presented similar correlation values for all properties.

A Study on Radial Curtain Plybamboo Form

Plybamboo is commonly made using chordwise bamboo strips. Previous studies have indicated that the bamboo utilization rate and the processing efficiency are low in manufacturing chordwise curtain Plybamboo. This paper presents a study on the manufacturing technology of radial curtain plybamboo form. Radial strips cut from bamboo were glued on the radial faces. The results showed: (1) the bamboo utilization rate of radial cutting strips was 15-20% higher than chordwise cutting strips, and the resin consumption was only approximately 50% of chordwise bamboo strips; (2) however, radial bamboo strips were more subject to lengthwise bending deformation than chordwise strips during drying. This lengthwise bending deformation can be effectively reduced or prevented by placing a hollow rigidity axle in the radial bamboo curtain rolls when using the bound drying method; (3) the hot pressing time of the radial curtain plybamboo form was approximately 50% of the chordwise composite plastic curtain plybamboo.

Use of a simple abrasivewear resistance test device to assess the suitability of selected hardwoods for wood flooring

Indigenous hardwoods off‑cuts generated by most mobile sawmillers are usually discarded resulting in under utilisation of timber and reduction of profit margins. The traditional indigenous species used in wood flooring have poor regeneration and slow growth thus cannot indefinitely sustain fast harvesting rates. Equipment required to assess the suitability of wood for specific applications is not readily available in Zimbabwe, so a simple abrasive‑wear resistance test device was used as an alternative. The device can be constructed in any wood technology laboratory equipped with basic machine tools. Hardness and abrasive‑wear resistance tests were performed on the radial and tangential faces of selected hardwoods to assess their performance in wood flooring. The results showed slightly higher hardness on the tangential face in poplar and mahogany only and that hardness increased with wood density. This study showed that neither the hardness value nor wood density can sufficiently explain increased abrasive-wear resistance because this is controlled by certain compounds found in wood cavities. However, ranking of selected hardwood species into different wood flooring traffic classes was similar for hardness values and abrasive‑wear resistance indices. This illustrated the potential for using abrasive‑wear resistance tests device as an alternative technique. Successful use of this device may assist in the identification of alternative species, relieve pressure on commercial indigenous species and facilitate collection of performance data and other wood species suitable for wood flooring. Key words: Hardness value, abrasion‑wear resistance index, basic wood density, wood flooring.

Effective non-destructive segregation of Eucalyptus grandis logs according to radial and tangential hardness

SummaryBasic density and hardness strongly influence the quality of high—value end products, such as floor boards. Significant variations in wood properties have been identified both within and amongst logs of plantation-grown Eucalyptus grandis (flooded gum or rose gum), which typically feature an inner cylinder of corewood characterised by low wood density, hardness and strength. These and other defects near the core are not easily detected until the log is sawn open and thus committed to a particular end-use. Despite this, it is important that only logs with suitably dense and hard wood in the core are processed into high-quality flooring.This study assessed the utility of a non-destructive tool, the Pilodyn, for gauging the radial variation in density and hardness amongst plantation-grown E. grandis logs prior to sawing. Pilodyn readings were taken at intervals across the ends of 40 typical fresh flooded gum logs about 5 m long. A sub-sample of 15 logs, representative of the Pilodyn penetration (P-pen) spectrum, was selected for more intensive testing. Janka hardness tests on air-dried specimens indicated characteristically low hardness (<3 kN) in the inner zone of every log. However, Janka hardness in the outerwood was found to be highly variable amongst logs. The segregation of logs into classes of P-pen readings (low, medium and high) provided a useful basis for predicting Janka hardness values: the correlation between the weighted average P-pen reading and weighted average Janka hardness was 0.80 and 0.81 for hardness on the radial and tangential faces respectively. Within each of the Pilodyn classes, the bending stiffness and strength, and compression strength parallel to grain of the timber, increased in the radial direction.Pilodyn tests on the end face of logs may assist processors to identify those logs with particularly problematic proportions of corewood and/or quality.

Observation of anisotropic water movement in Pinus radiata D. Don sapwood above fiber saturation using magnetic resonance micro-imaging

Magnetic resonance micro-imaging has been used to visualise the movement of water during the drying of Pinus radiata D. Don (radiata pine) wood samples of varying annual ring orientation and dimension. The drying process has shown a strong influence of annual ring orientation for thin boards with drying deviating from the classical core-shell model. Diffusion tensor micro-imaging shows the direction of greatest restriction to diffusion being in the transverse radial direction. Similarly, anisotropic values for T2 relaxation are observed, with values obtained when the transverse face is normal to the static magnetic field being higher than in the case when the radial or tangential faces are normal to the field.

Eficiência de um resíduo de origem petrolífera sobre a estabilidade dimensional da madeira de &lt;i&gt;Pinus&lt;/i&gt; sp. (pinus) e &lt;i&gt;Mimosa scabrella&lt;/i&gt; Bentham (bracatinga).

Na busca de alternativas de uso para um resíduo de origem petrolífera conhecido como "LCO" (Liquid Cycle Oil), avaliou-se a sua capacidade de aumentar a estabilidade dimensional das madeiras de Pinus sp.(pinus) e Mimosa scabrella Bentham (bracatinga). Esse resíduo foi testado na sua composição original e diluído em querosene comercial, em diferentes proporções. Foram avaliados a variação dimensional nos 3 eixos anatômicos, a variação volumétrica, o coeficiente de retratibilidade, anisotropia, e a variação da massa específica básica e a 12% de umidade, em diferentes etapas do estudo. Os resultados mostraram que não houve variação significativa da contração e inchamento máximos entre as amostras tratadas e as amostras não-tratadas (testemunhas), para ambas as espécies, ao nível de 5% de probabilidade. No entanto, observou-se uma redução no coeficiente de retratibilidade, com o aumento da concentração de LCO, para ambas espécies. De um modo geral, dentre as duas espécies estudadas, o pinus foi a que apresentou os menores valores dos índices avaliados. Os coeficientes de retratibilidade e anisotropia da bracatinga foram superiores aos do pinus, apesar da diferença não significativa entre as amostras tratadas e as testemunhas. Esses resultados indicam ter havido uma variação mínima entre as faces tangencial e radial, possivelmente por meioi de uma pobre penetração do LCO na parede celular. Como conseqüência, esse resultado pode estar relacionado ao fraco desempenho do produto químico testado, não conseguindo promover uma boa estabilidade dimensional da madeira de ambas as espécies. O aumento da concentração de LCO possibilitou um aumento na massa específica a 12% de umidade para ambas espécies. Esse resultado pode estar associado à presença de parte do produto remanescente nas paredes do lúmen celular e canais resiníferos. A aparência externa da madeira tratada foi outro fator restritivo ao uso do LCO.

HIGH TEMPERATURE DRYING FROM THE THREE PRIMARY ORTHOGONAL SURFACES OF LOBLOLLY PINE

While several permeability studies have been performed, little information is available on the flow of water in wood along its three orthogonal axes during high temperature drying. Much southern yellow pine construction lumber is dried at temperatures above 100°C, thus how water moves in wood is of concern. In this experiment individual Loblolly pine (Pinus taeda) sapwood cubes were coated on two of their three orthogonal faces (longitudinal, radial, and tangential) and the effect of this sealing on the drying rate was determined. From these cubes, drying rates from each of the three primary planes were determined. The free water movement/evaporation between the radial and tangential faces was not statistically different, while the longitudinal rate was approximately three times faster. In commercial practice, the faster longitudinal rate is negated by the very small portion of transverse surface area relative to total lumber surface area. This partially explains why end checking and moisture variation in high temperature dried southern yellow pine lumber are not significant causes of degrade. There was no statistically significant difference in permeability across the seasons tested.

Consolidant Distribution in Deteriorated Wood Treated With Soluble Resins

Scanning electron microscopy was used to study the distribution of synthetic resin consolidants after treatment of deteriorated wood samples by vacuum impregnation. These resins included Butvar B98, Acryloid B72, and Butvar B90. After the samples had been completely saturated with consolidant, evidence of resin could be found throughout cross sections taken from them, although examination of the samples showed that the resin was not uniformly distributed. Most strikingly, some tracheids could be observed to have heavy deposits of resin, which in some cases completely filled the cell lumen, while adjacent tracheids contained litde or no resin. The percentage of earlywood tracheids with visible resin deposits in a given sample area was then used as an indicator of resin content. Results showed that there was greater concentration of resin in the surface layers of radial or tangential faces than in the specimen core, as well as a tendency toward increasing concentration toward the end surfaces.

Consolidant Distribution in Deteriorated Wood Treated with Soluble Resins

Scanning electron microscopy was used to study the distribution of synthetic resin consolidants after treatment of deteriorated wood samples by vacuum impregnation. These resins included Butvar B98, Acryloid B72, and Butvar B90. After the samples had been completely saturated with consolidant, evidence of resin could be found throughout cross sections taken from them, although examination of the samples showed that the resin was not uniformly distributed. Most strikingly, some tracheids could be observed to have heavy deposits of resin, which in some cases completely filled the cell lumen, while adjacent tracheids contained litde or no resin. The percentage of earlywood tracheids with visible resin deposits in a given sample area was then used as an indicator of resin content. Results showed that there was greater concentration of resin in the surface layers of radial or tangential faces than in the specimen core, as well as a tendency toward increasing concentration toward the end surfaces.