Outer Board Research Articles

Effects of Microstructure and Chemical Composition on the Visual Characteristics of Flattened Bamboo Board

Flattened bamboo board is a new type of bamboo-based panel with various colors that maintains the natural texture of bamboo, and is gradually being used in indoor home decoration. Revealing the influence mechanism on the visual effect of flattened bamboo boards is the key to improving the processing of such boards for household materials. This study employed visual physical quantity measurement methods, field emission scanning electron microscopy, FTIR spectroscopy, and XPS to investigate the visual physical quantities, morphology, and chemical composition of flattened bamboo boards. The results showed that compared with the control samples, the bamboo outer layer boards were dark brown, with the largest ΔE* (38.55), while the outer boards were reddish-brown, with the largest a* (8.82). The inner boards were yellow-red and showed a lower ΔE* (6.55). Due to the elevated density, abundant inclusion, and wax, the bamboo outer layer board exhibited the highest glossiness and darkest color, followed by the outer board and the inner board. The FTIR spectroscopy revealed that hemicellulose decomposed, and the relative content of lignin increased, leading to color changes in the flattened bamboo boards. The bamboo outer layer board was the darkest due to changes in C=C bonds at 1600 cm−1 and 1509 cm−1. The surface color of the outer board was mainly red, which may be caused by C–O bonds at 1239 cm−1. The surface of the inner board was mainly yellow, which may be caused by the C–H stretching vibration of lignin at 1108 cm−1. XPS analysis showed that the proportion of C1 and O1 increased, while C2, C3, and O2 decreased, indicating that hemicellulose degraded at high temperatures, which increased the relative lignin content. Changes in the relative content of oxygen-containing functional groups and SiO2 in the flattened bamboo board were important factors responsible for the change in visual physical quantities.

ITER-grade tungsten limiters damage under high turbulent heat flux in the T-10 tokamak

The tungsten limiters were tested in the T-10 tokamak during the 2015–2017 experimental campaign. The limiters were made from the ITER-grade WMP “POLEMA” tungsten. Inspection of the tungsten limiters after experimental campaign has revealed their strong destruction due to the combination of the high heat and particle fluxes from the edge plasma toward the limiters surface. The influence of the edge tokamak plasma on tungsten limiters leads to significant cracking of the tungsten. Heat load up to 2 MW m−2 leads to micro-cracks at the grain boundaries. Heat loads exceeding 5 MW m−2 lead to macro-cracks formation. In the areas of highest heat loads, tungsten plates are melted and close to full destruction. In these zones, intensive sparking and arcing were observed. Arc craters have been scattered across the surface, and along the cracks. It is supposed that the nonambipolar flow due to the arcs and sparks can explain the observed overheating and melting of the tungsten surface. Disruptions and runaway electrons beams have driven extreme heat loads of more than 1 GW/m2 causing strong melting of the tungsten on the outer board of the ring limiter.

Analysis of Radar and Infrared Stealth Compatibility Design for Surface Ships

The stealth problem of surface ships is no longer a problem of a single physical field in a single frequency band. Under the severe threat of mutual coordination of enemy’s radar and infrared composite guidance mode, it is necessary to pay enough attention to the compatibility of radar and infrared stealth for surface ships. First, we analyzed the composite guidance threat of radar and infrared detection faced by surface ships at sea. Second, we analyzed compatibility design of radar and infrared stealth from ship hull outer board inclination, chimney parts and stealth coatings used by ships, separately. Finally, we clarified the direction for the subsequent research and development of stealth technology for surface ships.

An experimental study on the aerodynamic performance degradation of a UAS propeller model induced by ice accretion process

An experimental study was performed to investigate the effects of ice accretion on the aerodynamic performances and wake characteristics of a propeller model used for Unmanned-Aerial-System (UAS) under different icing conditions (i.e., rime vs. glaze). The experimental study was conducted in the unique Icing Research Tunnel available at Iowa State University (ISU-IRT). In addition to acquiring the important features of ice accretion on the rotating propeller blade using a “phase-locked” imaging technique, the wake characteristics of the rotating UAS propeller under the different icing conditions were also resolved by using the Particle Imaging Velocimetry (PIV) technique along with the time-resolved measurements of aerodynamic forces and power consumption of the UAS propeller model. Both “free-run” and “phase-locked” PIV measurements were performed on the propeller model at the different stages of the icing experiments (i.e., before, during and after the dynamic icing processes) to provide both the instantaneous flow characteristics and the ensemble-averaged flow statistics (e.g., mean velocity, vorticity, and turbulence kinetic energy) in the wake of the rotating propeller model. To the best knowledge of the authors, this is the first work of its kind to provide detailed, temporally-resolved wake flow field measurements of UAS propeller under real icing conditions. It is found that while the rime ice accretion could closely follow the original profiles of the propeller blades, the glaze ice usually forms into very irregular structures that can significantly disturb the wake flow field of the rotating propeller model, generating the much larger and more complex vortices. Such complex large-scale vortices are found to enhance the turbulent mixing in the propeller wake and produce an evident velocity deficit channel around the outer board of the propeller blades, providing direct evidences in elucidating the dramatic decrease in thrust generation and the significant increase in power consumption of the rotating propeller model in icing conditions. The findings derived from this study are believed to be essential and very helpful to elucidate the underlying mechanisms of the aerodynamic performance degradation of ice accreting UAS propellers.

Wood anatomy and construction technique of Late Bronze Age rural cartwheels

A recent archaeological discovery of a Late Bronze Age cartwheel in north eastern France (Erstein, Alsace) has shed important new light on the technical development of wheels in Europe. The well-preserved wooden fragments were discovered at the base of a water well and were in secondary use as wedges to adjust a well lined with a hollowed tree trunk. Dendrochronological and radiocarbon results gave a chronological classification to the Late Bronze Age in 13th century BCE. Although the discovered wheel was not complete, these fragments provide a clear picture of the overall wheel design and allow a detailed reconstruction. The wheel disc comprises three parts that are held together by stump tenon joints and two mutually curved insertion strips with dovetail profiles that are located on opposite sides. The two outer boards have crescent-shaped cut-outs. The planks for the disc wheel were crafted from sycamore maple (Acer pseudoplatanus), and the strips and tenons were crafted from hazel (Corylus avellana) and ash (Fraxinus excelsior), respectively. The results of wood identification indicate that the selection and processing of wood were predominantly based on specific knowledge and supra-regional traditions. The recent find from Erstein is also compared with what is currently known from other Bronze Age sources from Europe. Together, these results clearly demonstrate that there were almost no regional variations in construction techniques from south of the Alps to northern Europe.

Wood defects during industrial-scale production of thermally modified Norway spruce and Scots pine

This research investigates wood defects, particularly the formation of surface cracks, during the production of thermally modified wood and its exposure to cyclic moisture changes. Boards of Norway spruce and Scots pine originating from different steps within the production of ThermoWood® were collected and wood defects were investigated at macroscopic and microscopic scale. Subsequently, the wood was exposed to capillary wetting cycles to record its sensitivity towards cracking. After the modification process, typical anatomical defects of conventional kiln-drying became more frequent and severe, with the magnitude being to some extent depending on the presence of defects in the raw material. At microscopic scale, damages to ray parenchyma and epithelial cells as well as longitudinal cracks within the cell walls of earlywood tracheids were evident in thermally modified wood. Despite a lower water uptake and higher dimensional stability, thermally modified wood was more sensitive to surface cracking during wetting cycles than unmodified wood, i.e. at the outside face of outer boards (near bark). For limiting surface cracking of thermally modified wood during service life, the use of high-quality raw material, the exposure of the inside face of the boards (near pith) and the application of a surface coating are considered beneficial.

Surface mould and blue stain fungi on coated Norway spruce cladding

The study describes the development of surface mould and blue stain fungi on painted wooden claddings exposed to outdoor weathering. The materials consisted of Norway spruce (Picea abies) claddings that were processed from inner boards, outer boards, and edge-grained boards with known origin. Heartwood proportion, density, annual ring width, knot diameters and relative knot area were measured, and all boards were coated with the same water-borne alkyd modified acrylic paint system. Most of the tangentially sawn boards were coated on the side facing the pith, but a sub-sample was coated on the opposite side for comparison. The specimens were exposed with a 45° angle of inclination facing south in a field trial in Oslo from 2007 to 2011, and mould growth was evaluated visually according to EN 927-3. The development of mould rating was described with an ordinal logistic regression model. The model predicts expected mould rating to follow a sigmoid curve with some deviation in the first part. Neither wood properties nor manufacturing characteristics had any significant effect on the model, and this may in part be due to the use of a high performance coating system.

Effects of Outdoor Weathering and Wood Properties on Liquid Water Absorption in Uncoated Norway Spruce Cladding

A comparison of liquid water absorption in uncoated Norway spruce (Picea abies L.) claddings before and after 1 year of outdoor weathering was performed. The study was based on 150 specimens from two sites with high-productive forest and two sites with low-productive forest in southern Norway. The specimens included inner and outer boards; density, annual ring width, and proportion of heartwood were recorded. Water absorption increased after weathering. The relative change of short-term absorption was larger for outer boards than for inner boards, whereas it did not vary between origins. The outer boards also had more cracks than the inner boards after weathering. The differences between inner and outer boards were explained by different heartwood proportion and different annual ring orientation. The variability of short-term absorption increased after weathering since the sample groups with the highest initial absorption also had the largest increase after weathering. The change of long-term absorption did not vary between inner and outer boards or between origins.

Choosing green sawing dimensions for Norway spruce from stochastic simulations

The high accuracy of log positioning and the stability of saw blades in breakdown machinery in modern sawmills have reduced the need to add margins for sawing variations. Oversize green sawing dimensions are still needed, but mainly to allow for drying shrinkage. This has put a new focus on better adapting green sawing dimensions to the shrinkage behavior of wood. In this study, a method for optimization of green sawing dimensions using stochastic simulation is presented. Normal distributions were generated for planed dry dimensions, kerf width, and target moisture content. The minimum share of boards exceeding the specified dry dimensions was decided, and deformations in boards from all positions in the cross section in a number of logs were simulated. The simulated shrinkage allowance from stochastic simulations was compared to experimental results from an industry test and to finite element results based on material data for Norway spruce. The results showed that the green width of the sawn boards should increase when the number of boards in the center yield increases. The green thickness of boards should be thinner for center boards and outer boards than for inner boards.

Liquid water absorption in uncoated Norway spruce (Picea abies) claddings as affected by origin and wood properties

Uncoated Norway spruce specimens from different spatial positions within stems from two origins with different growth conditions were exposed to liquid water over a prolonged time, and apparent diffusion coefficients and rates of void filling were calculated from sorption curves. Both apparent diffusion and rate of void filling were significantly affected by origin and by the difference between inner and outer boards. The differences between inner and outer boards were explained by heartwood proportion and density, but some effects of origin remained when these properties were accounted for. The apparent diffusion coefficient was reduced by increasing density, and increased by increasing heartwood proportion. Void filling rate was reduced by both increasing density and increasing heartwood proportion. Since the effect of heartwood proportion was more pronounced in the material from the highly productive area, it may have been confounded with properties of juvenile wood.

Active particle control experiments and critical particle flux discriminating between the wall pumping and fuelling in the compact plasma wall interaction device CPD spherical tokamak

Two approaches associated with wall recycling have been performed in a small spherical tokamak device CPD (compact plasma wall interaction experimental device), that is, (1) demonstration of active particle recycling control, namely, ‘active wall pumping’ using a rotating poloidal limiter whose surface is continuously gettered by lithium and (2) a basic study of the key parameters which discriminates between ‘wall pumping and fuelling’. For the former, active control of ‘wall pumping’ has been demonstrated during 50 kW RF current drive discharges whose pulse length is typically ∼300 ms. Although the rotating limiter is located at the outer board, as soon as the rotating drum is gettered with lithium, hydrogen recycling measured with Hα spectroscopy decreases by about a factor of 3 not only near the limiter but also in the centre stack region. Also, the oxygen impurity level measured with O II spectroscopy is reduced by about a factor of 3. As a consequence of the reduced recycling and impurity level, RF driven current has nearly doubled at the same vertical magnetic field. For the latter, global plasma wall interaction with plasma facing components in the vessel is studied in a simple torus produced by electron cyclotron waves with Ip < 1 kA. A static gas balance (pressure measurement) without external pumping systems has been performed to investigate the role of particle flux on a transition of ‘wall fuelling’ to ‘wall pumping’. It is found that a critical particle flux exists to discriminate between them. Beyond the critical value, a large fraction (∼80%) of pressure drop (‘wall pumping’) is found, suggesting that almost all injected particles are retained in the wall. Below it, a significant pressure rise (‘wall fuelling’) is found, which indicates that particles are fuelled from the wall during/just after the discharge. Shot history effects (integrated particle recycling behaviour from the plasma facing surfaces) are seen on that the critical particle flux is reducing from 0.8 × 10−4 to ∼0.1 × 10−4 Torr during the experimental campaign (∼3000 shots). In the wall pumping pressure range the wall pumping fraction is reduced with increasing surface temperature up to 150 °C.

CRRES microelectronic test chip

The JPL CRRES chip was designed and fabricated in 1985 and included in the CRRES MEP. MOSFET matrix results show the effect of shielding on radiation-induced MOSFET threshold voltage shifts and channel mobility degradation. Shielded (middle board) MOSFETs have a threshold-voltage damage factor that is approximately three orders of magnitude smaller than would be estimated from Co-60 ground tests. Unshielded (outer board) MOSFETs have a threshold-voltage damage factor that would be estimated from Co-60 ground tests. Temperature swings as large as 23 degrees C with a 22.5 orbit periodicity affected the MOSFET data and were removed from the data in order to reveal the radiation effects. This experiment demonstrated the feasibility of characterizing MOSFETs in a matrix, thus reducing the complexity and mass of the experiment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Investigation of the SOL using a multi-element instrumental poloidal limiter

The distribution of currents along both sides of a ring poloidal limiter which was electrically connected to a liner, as well as the distribution of floating potentials with respect to the liner, have been measured in a tokamak TMI ( R = 40 cm, r L = 7 cm, B T = 1.3–1.6 T, I P = 15–40 kA). Sign inversion dependences on poloidal angles have been obtained. By using an array of Langmuir probes, covering a 200° poloidal angle and installed on the outer board of the torus, the electron temperature, plasma density and floating potential in the SOL have been measured. These parameters were distributed in a complicated pattern. By using the measured values and a theoretical model for the Pfirsch-Schlüter currents, estimations have been made of the currents flowing from the plasma to the individual elements of the limiter. A satisfactory agreement with the measured values has been obtained. This shows that the distribution of the currents is governed, basically, by the toroidal drift and the plasma-limiter contact. Results are presented, which characterize changes of the plasma potential when the distribution of potential along the limiter is specified by an external power supply.

垂直通気層構法における防湿・防露設計を対象とした定常計算方法に関する提案 : 通気層による構造体の防湿効果に関する研究 その4

The efficiency of vapor discharge by vertical air layers has been extensively studied in our previous papers when outer board composing air layer excludes completely vapor transmission. It is the purpose of this paper to study the efficiency of vapor discharge by vertical air layers when outer board is made of materials with vapor transmission effect. A quantitative comparison is made between the results obtained in present experiments and those in previous experiments. Furthermore, we propose a computation model of vapor transmission for the prevention design of moisture and condensation in building with vertical air layers. Comparing the computed values with the experimental results, a fairly good correnspondence is observed between these two values. Finally, the values of equivalent permeance resistance are presented for each thickness of air layer in two cases where the heights of air layer are 3 and 6 meters.

Tests on Nailed and Glued Layered Timber Cylindrical Shells

One shell was of nailed construction while the other was glued or nail-glued with the gluing pressure being provided by permanently nailing the layers together. The shell membrane was constructed of three layers of model boards or strips giving a total thickness of ½ in. (12.5 mm) with the outer boards running transversely and boards in the central layer running longitudinally. The shells were tested under a radial load applied by means of an airbag. The nailed shell failed at a load of 75 psf (3.6 kN/m²) whereas the nail-glued (glued) shell sustained a load of 160 psf (7.5 kN/m²) before the membrane separated from the edge beam and diaphragm at one corner. The deflections of both shells under load cycling were about twice those predicted by an analysis based on the Schorer approximation, while no analysis was made for the nailed shell under initial load. This error in the calculated deflections was most likely due to the shear deformations in the shell membrane which were ignored in the analysis.

A New Method of protecting Wood against Marine Borers

During the last five years the authors have supervised 11 series of exposure tests, ranging from 6 to 25 months, of Japanese cedar samples tested in various ways to prevent attack by marine borers. Some of the new methods were applied to more than 20 ships sailing to the southern seas, but unfortunately most of them were lost or destroyed before ade_??_uate tests could be completed.Protective methods generally in use for saving wooden ships from borers are either chemical or mechanical. The chemical method kills the borers by painting or injecting preservatives or toxicants into the wood. The mechanical method prevents borers from reaching the timber by sheathing it with sheet metal or specially treated fabric. Observation of exposure tests on materials treated by these two methods have given the following results:1) Painting the exposed surface with a chemical substance harmful or disagreeable to marine borers such as copper paint, is commonly practiced as the most effective and practical method in use at present. This method is not permanent because the protective substance either gradually leaches out, or the coating itself is destroyed by abrasion in a very short time. Subsequently frequent docking and renewal are necessary.2) Sheathing the bottom with an outer board with an intervening layer of tar paper has been considered resistant, but their experiments show it quite ineffective against both shipworms and boring crustaceans over a two year period.3) Impregnating the wood with preservatives and toxicants is cons dered better than co ting, but the large amounts of impregnants necessary, and the increase of weight to the ship are undesirable.4) So far as the weight i concerned, sheathing the bottom of a ship with thin wood impregnated with creosote or copper hydroxide is better than injecting the hull itself. But the impregn ted boards lengthen the life of the ship only until the in ected tox cants leach out of the thin wood, which is usually within a year.No chemical method depending on toxicity lasts over one or two years.Next they tested various methods of applying soluble urine resin compounds, which may be so treated as to make a hard, unsoluble outside layer, giving mechanical as well as chemical protect on. Results were obtained as follows:1) Test pieces painted with urine resine compounds were not attacked by the borers after one and one half years. and after two years the test pieces were attacked slightly only at one corner where the coating abraded. The method is more effective than painting with copper.2) The two year tests of an intervening layer of urine resin compounds give complete protection against the borers. Veneer plates with two or three protective layers of urine resin compounds may be applicable for the outer protective boards of ship.3) Samples sheathed with thin boards injected with urine resin compounds lasted two years against borers.4) Another important result of this method is the waterproof quality imparted to the woodtself. The weight of samples after two years test in the sea showed only 10-20% increase remakably lower than that of the other methods which allow sometimes up to 120% increase in weight.

On framing lock gates without iron work

A recent archaeological discovery of a Late Bronze Age cartwheel in north eastern France (Erstein, Alsace) has shed important new light on the technical development of wheels in Europe. The well-preserved wooden fragments were discovered at the base of a water well and were in secondary use as wedges to adjust a well lined with a hollowed tree trunk. Dendrochronological and radiocarbon results gave a chronological classification to the Late Bronze Age in 13th century BCE. Although the discovered wheel was not complete, these fragments provide a clear picture of the overall wheel design and allow a detailed reconstruction. The wheel disc comprises three parts that are held together by stump tenon joints and two mutually curved insertion strips with dovetail profiles that are located on opposite sides. The two outer boards have crescent-shaped cut-outs. The planks for the disc wheel were crafted from sycamore maple (Acer pseudoplatanus), and the strips and tenons were crafted from hazel (Corylus avellana) and ash (Fraxinus excelsior), respectively. The results of wood identification indicate that the selection and processing of wood were predominantly based on specific knowledge and supra-regional traditions. The recent find from Erstein is also compared with what is currently known from other Bronze Age sources from Europe. Together, these results clearly demonstrate that there were almost no regional variations in construction techniques from south of the Alps to northern Europe.