Influence of hot pressing technological parameters on plywood bending properties

Different types of wood are used to manufacture of various wood products. In direct production processes, additional resources such as energy, adhesives, labor, etc. are also used. In line with sustainable environmental policies, all resources must be used more rationally, while simultaneously increasing the efficiency of the direct production processes. This research examined whether it is possible to reduce energy and labor resources in the technological process of hot pressing of birch plywood (nominal thickness 9 mm), by varying the holding time under pressure, pressure, and adhesive consumption. The Box-Behnken experimental design for a multifactor experiment was used to investigate the influence of technological parameters of plywood pressing. The highest strength in static bending both parallel and perpendicular to the plywood grain was achieved by pressing plywood with the following gluing parameters: highest pressing pressure, 3.2 MPa; minimal holding time under pressure, 9 minutes; and average phenol-formaldehyde adhesive consumption 150 grams per square meter.

Research of Supporting Ability and Prediction of Residual Life of Casing Pipes at General Corrosion Damage of Inner Surface

The detection and the measuring of the developing damages must be accompanied by evaluation of the supporting ability of the design in terms of the increasing size of a defect. If the type of damage is dominant one on the further period of the operation, so the received functional dependences can be used to predict a residual life of the designs. As illustrated by the casing pipes of 168.3 mm diameter, where the dominant damage is the general corrosion of the inner surface, the algorithm to receive the expression for the calculation of coefficients of the lowering of the supporting ability to the excessive inner pressure in the function of the nominal thickness of pipes wall and corrosion depth is shown. The algorithm of the application of the received expression to calculate the residual life of the damaged casing pipes is given.

Analysis of Linear Dimension Accuracy of Sheet Metal Bending

Working on the design of the products obtained by the V-bending, the engineer uses the nominal thickness of the material. In this case, the problem is to evaluate the accuracy of the linear dimensions of the resulting products due to deviations in the thickness of the material and the manufacturing technology of the steel sheets. Article presents analysis of linear dimension accuracy for V-bending for the metal cold-rolled and hot-rolled sheets with thickness 1.0…8.0 mm and width from 1000…1500mm. Proposed method is based on the calculation of difference between nominal flat length and flat lengths corresponding maximum and minimum thickness of the metal sheet.

Linking Visual and Stress Wave Grading of Beech Wood from the Log to the Sawmill Product

The quality potential and possibilities of using beech logs and sawn wood was investigated. Twenty-seven beech logs, with a mean diameter of 48 cm, were cut from 10 trees from a Hacquetio epipactidis-Fagetum site in SE Slovenia. The trees were pre-selected according to the national 5-level quality scale for forest stand evaluation, using two trees per class. Beech logs were classified according to the EN 1316-1 and sawn afterwards into unedged boards of 35 mm nominal thickness. Altogether, 250 boards were visually graded according to the rules of the European Organisation of the Sawmill Industry (EOS). Longitudinal vibration of logs and boards with the determination of stress wave velocity by MTG timber grader was additionally included into the quality assessment. In the case of logs, we confirmed significance of the relationship between visually assessed log quality and stress wave velocity. The stress wave velocity in logs was also related to the stress wave velocity in boards, where it varied considerably, especially for low-graded material. In the case of sawn wood, the relationship between sawn wood grade and stress wave velocity was insignificant. The research confirmed the possibility of presorting of logs, visually or non-destructively, for better classification and utilization of sawn timber.

Deposition of Low-Resistivity Aluminum Thin Films Via Application of Substrate Bias During Magnetron Sputtering

In this study, the critical role of substrate bias during the sputter deposition of Al thin films is discussed. Two sets of Al thin films having a nominal thickness of 300 nm were deposited at sputtering pressures of 4.1 and 1.5 mTorr, respectively, with an applied negative substrate bias in the range of 0-200 V. It was found that the microstructure, surface roughness, film resistivity and grain size were greatly altered by the combination of bias magnitudes and sputtering pressures. The sputtering pressure of 4.1 mTorr resulted in greater changes in the film properties with the application of substrate bias, and a lesser but still significant degree was observed for the films deposited at 1.5 mTorr. The resistivity values for the films deposited at 1.5 mTorr were found to be significantly lower, with the lowest resistivity value of 3.1 µΩcm achieved at a substrate bias of 50 V. Based on grain size measured by the line intercept method and MayadasShatzkes grain boundary scattering model, the resistivity contribution of grain boundary scattering for the lowest-resistivity film was found to be 0.37 µΩcm, which indicates that the film resistivity in the optimized condition is close to the known bulk resistivity of 2.65 µΩcm.

Heat Transfer Through Insulating Glass Units Subjected to Climatic Loads

One of the structural elements used in the construction of insulating glass units (IGUs) are tight gaps filled with gas, the purpose of which is to improve the thermal properties of glazing in buildings. Natural changes in weather parameters: atmospheric pressure, temperature, and wind influence the gas pressure changes in the gaps and, consequently, the resultant loads and deflections of the component glass panes of a unit. In low temperature conditions and when the atmospheric pressure increases, the component glass panes may have a concave form of deflection, so that the thickness of the gaps in such loaded glazing may be less than its nominal thickness. The paper analyses the effect of reducing this thickness in winter conditions on the design heat loss through insulating glass units. For this purpose, deflections of glass in sample units were determined and on this basis the thickness of the gaps under operating conditions was estimated. Next, the thermal transmittance and density of heat-flow rate determined for gaps of nominal thickness and of thickness reduced under load were compared. It was shown that taking into account the influence of climatic loads may, under certain conditions, result in an increase in the calculated heat loss through IGUs. This happens when the gaps do not transfer heat by convection, i.e., in a linear range of changes in thermal transmittance. For example, for currently manufactured triple-glazed IGUs in conditions of “mild winter”, the calculated heat losses can increase to 5%, and for double-glazed IGUs with 10–14 mm gaps this ratio is about 4.6%. In other cases—e.g., large thickness of the gaps in a unit, large reduction in outside temperature—convention appears in the gaps. Then reducing the thickness of the gaps does not worsen the thermal insulation of the glazing. This effect should be taken into account when designing IGUs. It was also found that the wind load does not significantly affect the thickness of the gaps.

Differential Cross Section Measurements of the $^{12}C(d,p_{1,2,3})^{13}C$ Reaction, in the Energy Range E$_{d,lab}$= 900-2000 keV, Suitable for NRA

Absolute differential cross section measurements of the $^{12}C(d,p_{1,2,3})^{13}C$ reaction were performed in the projectile energy region Ed,lab = 900-2000 keV (in steps of 25 keV) and for detector angles between 145° and 170° (in steps of 5°) using as targets 99.9% purity self-supported natural carbon (98.9% 12C – 1.1% 13C) foils of nominal thickness ca. 1×10$^{18}$ at/cm2. The overall error in the absolute differential cross section measurements varied between ~8-30%. The results, presented in both graphical and tabular form, are compared with already published data and an attempt is made to explain the occurring differences. The strong influence of the resonance mechanism is presented and discussed.

Фотолюминесценция гетероструктур CdTe/ZnTe с номинальными толщинами слоев CdTe от 1 до 8 монослоев, выращенных методом атомного наслаивания

The luminescence of CdTe layers with a nominal thickness of 1, 2, 4, and 8 monolayers grown by atomic layer epitaxy in ZnTe matrix was studied. It is shown that layers with a thickness of 1 and 2 monolayers are homogeneous, while layers with a nominal thickness of 4 and 8 monolayers are the planar QD arrays. The sizes of QDs and their size dispersion increase with an increase in the nominal thickness of CdTe layer. The luminescence excitation spectra of CdTe layer in the samples vary significantly. It has been shown that, depending on the energy distance between the CdTe and ZnTe exciton levels, the ratio of contributions to the energy transfer via the exciton ZnTe and charge carriers varies greatly.

A Detailed Study of the 12C(d,p0)13C Reaction at Detector Angles between 135 ° and 170 °, for the Energy Range Ed,lab = 900-2000 keV

The differential cross sections of the 12C(d,po)13C reaction applied to the determination of the depth distribution of carbon in near-surface layers of materials were determined in the projectile energy region F,dtiab — 900-2000 keV (in steps of 25 keV) and for detector angles between 135 ° and 170 ° (in steps of 5 ° ) using as targets 99.9% purity self-supported natural carbon (98.9% 12C - 1.1% 13C) foils of nominal thickness ca. lxlO18 at/cm2. The overall error in the absolute differential cross section measurements varied between ~6-22%. The results were compared with already published data and the explanation of the occurring differences was attempted.