Top PDF The influence of Moisture Content on Ultrasonic Velocity in Wood

The influence of Moisture Content on Ultrasonic Velocity in Wood

The influence of Moisture Content on Ultrasonic Velocity in Wood

Scheffe test značajnosti razlike brzine prolaska ultrazvuka u radijalnom smjeru kroz drvo bukve srednje gustoće različitih sadržaja vode .... Scheffe test značajnosti razlike brzine pro[r]

42 Read more

The influence of moisture content variation on fungal pigment formation in spalted wood

The influence of moisture content variation on fungal pigment formation in spalted wood

igniarius (L.) Quél. and found that moisture content strongly influences the antagonistic reactions with pig- ment production in wood. However, research under la- boratory conditions is limited, and a more elaborate and consistent investigation was necessary to determine the optimal conditions for pigmentation for given wood spe- cies by fungal species utilized in spalting. This study investigates the direct influence of moisture content of specific wood substrates on fungal pigmentation, and the results are important for manipulating fungal pig- mentation for spalting production. The ability to ma- nipulate fungal reactions through moisture content changes in wood, offers a chance to enhance the pig- mentation intensity and patterns currently available with spalted woods. It also offers an opportunity to add con- siderable value to underutilized hardwood species.
Show more

10 Read more

Investigation of wood properties that influence the final moisture content of air-dried sugi (Cryptomeria japonica) using principal component regression analysis

Investigation of wood properties that influence the final moisture content of air-dried sugi (Cryptomeria japonica) using principal component regression analysis

Prior to the drying test, the surfaces of the sample, except the two surfaces normal to the thickness direction of ori- ginal lumber, were sealed with silicone and aluminum foil (Fig. 1b). The weight of the sealing was calculated by subtracting the weight before sealing from the one after sealing. Thereafter, the samples were placed and air-dried for 28 days in a conditioning room at a temperature of 20 ± 1 °C and a relative humidity of 44 ± 2 % RH. The weight of each sample was measured once in a day. After the drying, the samples were oven-dried until the constant weight was attained and their MC i and moisture content
Show more

6 Read more

Influence of moisture content on the vibrational properties of hematoxylin-impregnated wood

Influence of moisture content on the vibrational properties of hematoxylin-impregnated wood

The specific dynamic Young's modulus (E/v) and loss tangent (tan6) of hema- toxylin-impregnated wood were determined in the relative humidity (RH) range of 0%-97%, an[r]

5 Read more

Influence of moisture content on estimating Young’s modulus of full-scale timber using stress wave velocity

Influence of moisture content on estimating Young’s modulus of full-scale timber using stress wave velocity

For the purposes of forestry management and carbon stocks meant restraining carbon emissions, wood utiliza- tion, especially the material use of the wood which is not broken down of wood as much as possible attracts attention all over the world. In the case of material use, the quality assessment of the actual timber being used may be neces- sary since timber is a biologically varying material. Among the quality assessments of timber, especially while seeking the mechanical properties of such structural lumber in use, grading according to Young’s modulus plays a very impor- tant role [1]. Grading timber according to Young’s modulus not only allows us to understand the elastic properties of the timber individually, but also allows the fracture strength of the timber to be predicted. In recent years, grading lum- ber has become a major issue, particularly in Europe and the United States.
Show more

11 Read more

Influence of moisture content on the wave velocity to estimate the mechanical properties of large cross-section pieces for structural use  of scots pine from spain

Influence of moisture content on the wave velocity to estimate the mechanical properties of large cross-section pieces for structural use of scots pine from spain

Nondestructive techniques are widely used in several fields of technology to estimate the properties of materials. Some of these technologies are wave-based and have been successfully used in recent decades to estimate the mechanical properties of wood. Interest in these applications and the need for reliable estimations are increasing, in order to guarantee the safety and improve the efficiency of timber structures. One of the main fields in which these technologies need to be improved concerns the influence of certain parameters such as the moisture content of wood.
Show more

14 Read more

Influence of moisture on the vibro-mechanical properties of bio-engineered wood

Influence of moisture on the vibro-mechanical properties of bio-engineered wood

Wood modification by specific white rot fungi reduces density without significantly altering the stiffness of the material, as a result of selective delignification [ 13 ], and thus improves the acoustic properties [ 14 , 15 ]. The main objective of the present study was to improve the under- standing of the impact of incubation with Physisporinus vitreus (Pers.) P. Karst on the hygroscopicity and vibro- mechanical behavior of resonance Norway spruce wood. The hypothesis was that changes in the arrangement of the molecules of lignin, hemicelluloses, and cellulose in the fungi-treated wood will change the hygroscopicity and vibro-mechanical behavior of the material. Twin samples of control (untreated) and fungi-treated resonance Norway spruce wood were exposed to a stepwise change in the RH, and the vibro-mechanical properties were measured using a free–free beam vibration method. Changes in the moisture content (MC), specific moduli of elasticity, and internal frictions in a cycle of sorption–desorption were measured. Using Fourier transform infrared spectroscopy (FT-IR) and dynamic vapor sorption (DVS) system, change in molec- ular architecture of the wood and hygroscopic properties was analyzed. The expectation was to elucidate the reac- tion and adaptation of the fungi-treated wood with fungi to the change in the RH, for further improvement of the fungal modification processes.
Show more

9 Read more

Influence of a wide range of moisture contents on the Poisson’s ratio of wood

Influence of a wide range of moisture contents on the Poisson’s ratio of wood

Abstract This study investigates the effect of a wide range of moisture contents (0–177 %) on the Poisson’s ratio of wood taken from Japanese cypress and magnolia by conducting longitudinal compression tests. Through analysis of variance and multiple comparisons, it was found that when the moisture content is below the respective fiber saturation point Poisson’s ratio decreases with increasing moisture content. In contrast, at moisture contents above the fiber saturation point, the Poisson’s ratio increases with moisture content. The same tendency was observed in both wood species, but the effect was more pronounced in magnolia than Japanese cypress.
Show more

5 Read more

The influence of the moisture content on the electrical resistance of two types of cork stoppers

The influence of the moisture content on the electrical resistance of two types of cork stoppers

With respect to the curve fitting process for deter- mining the ER-MC curves of wood, the literature contains many expressions. The regression model used in the present study was proposed by Samuelsson (1990): log(Log(R) + 1) = axh + b, where R is the electrical resis- tance (M Ω ) and h is the moisture content (%). This expression was used in an extensive work performed by Forsén and Tarvainen (2000), who determined the coeff icients a and b for different types of European

5 Read more

Identification of Moisture Content in Coal Sample by using Ultrasonic NDT

Identification of Moisture Content in Coal Sample by using Ultrasonic NDT

Abstract - Coal is an extremely complex material and exhibits a wide range of physical and chemical properties. The rapidly expanding use of coal made it necessary to devise acceptable methods for coal analysis with the goal of correlating composition and properties with behavior. As a part of the multifaceted program of coal evaluation, new methods are continually being developed and the already accepted methods may need regular modification to increase the accuracy of the technique as well as the precision of the results. The use of ultrasonic testing for material characterization not only play a important role in quality assurance during in-manufacture inspection but also can serve as a powerful tool for life prediction technology during in-service inspection, residual life assessment and plant life extension . The measurement of ultrasonic parameters has been used for determining material properties for many years, but with the advent of modern signal processing techniques it is possible to extract significantly more information from ultrasonic signals. In this paper an attempt is made to characterize the Moisture content in Coal Sample by ultrasonic Non destructive techniques by measuring various NDT parameters of Coal Sample such as, ultrasonic velocity, attenuation, etc.
Show more

5 Read more

Non-destructive evaluation of moisture content in wood using ground-penetrating radar

Non-destructive evaluation of moisture content in wood using ground-penetrating radar

A further goal of this work is to study how the distance be- tween the radar antennas affects the amplitude of the received signal. For each considered humidity level, the amplitude of the direct wave is then measured with antennas placed at 30 different distances. In Fig. 8, the direct-wave amplitude nor- malised to the amplitude of the direct-air wave is plotted as a function of the distance between transmitting and receiv- ing antennas, when the humidity by mass water is 18.18 %. As expected, the amplitude shows an exponential attenuation when the distance increases. In Fig. 9, the normalised ampli- tude of the direct wave is plotted as a function of the humid- ity level for both parallel and orthogonal polarisation cases, when the distance between the antennas is 11 and 16 cm, re- spectively. It can be noticed that, when the moisture content increases, the normalised amplitude at short distances turns out to be higher than one when the electric field is orthog- onal to the wood fibres. This may be due to a superposition of direct and direct-air waves. In particular, in this configu- ration the distance T –R is small and the dielectric constant is also small; hence the velocity is high and the propagation time is small, which allows for the superposition of direct and direct-air waves.
Show more

7 Read more

Effect of coupling media on velocity and attenuation of ultrasonic waves in Brazilian wood

Effect of coupling media on velocity and attenuation of ultrasonic waves in Brazilian wood

During the tests, a constant pressure of 35 kPa was applied on the transducers with a device with a 1000-N load cell (Fig. 3). For longitudinal and transverse waves, the time of wave propagation and the initial and fi nal wave amplitudes were collected; the measurement procedure was performed fi ve times to determine the repeatability of the tests. After the readings, a careful cleaning of the specimen and transducer was performed using water. Although there was no deep water penetration into the specimen, the specimen remained in a covered and aired location and was only tested again after completely drying (moisture content around 12%) to prevent any interference resulting from the moisture content or by coupling penetration, as cited by Kamioka and Kataoka 5
Show more

6 Read more

Effect Of Air Velocity And Moisture Content On Solid Waste Combustion

Effect Of Air Velocity And Moisture Content On Solid Waste Combustion

Since the beginning, humankind has been generating waste, be it the bones and other parts of animals they slaughter for their food or the wood they cut to make their carts. With the progress of civilization, the waste generated became of a more complex nature. At the end of the 19th century the industrial revolution saw the rise of the world of consumers. Not only did the air get more and more polluted but the earth itself became more polluted with the generation of nonbiodegradable solid waste. The increase in population and urbanization was also largely responsible for the increase in solid waste.
Show more

24 Read more

CFD MODELLING OF MOISTURE CONTENT, AIR VELOCITY & THERMAL PATTERNS IN THE TOMBS OF HOREMEHEB IN VALLEY OF KINGS

CFD MODELLING OF MOISTURE CONTENT, AIR VELOCITY & THERMAL PATTERNS IN THE TOMBS OF HOREMEHEB IN VALLEY OF KINGS

The difference in flow patterns and relative humidity contours for the present two cases indicated the effect of number of visitors and that the visitors’ location strongly affects the detailed flow pattern and relative humidity distributions, and it is clear that visitors obstruct the flow area in the relatively long pass-way that results in an increase of air flow velocity. It should be emphasized here that the visitors represent a huge heat load both in sensible and latent sense, and this result in an increase of air temperature and humidity inside tomb. A corresponding proper number of simultaneous visitors should not be exceeded in order to maintain air flow velocity, temperature and humidity within allowable limits. The above shown predictions indicate the usefulness of floor extracts that preserve the archaeological value of the tomb. Investigations were proceeded to investigate the influence of the recirculation zones on the visitors’ occupancy zone and also on the supplied fresh air to the tomb.
Show more

6 Read more

Influence of different moisture content on engineering properties of tamarind seeds

Influence of different moisture content on engineering properties of tamarind seeds

Based on the results, the following conclusions were drawn. The engineering properties are different for seeds for their different moisture contents. Bulk density was found to show increasing trends with the increasing moisture content (5%-15% db). Similar trends were seen in true and tap densities. Angle of repose was found to increase for whole and split tamarind seed as well as for different moisture content regulated seeds. Coefficient of friction showed an increasing trend for all threes surfaces, i.e. plywood, cast iron and stainless steel for increasing moisture content (5%-15% db).Textural properties such as toughness and hardness, showed an decreasing trend with the increase in moisture content of tamarind seeds.
Show more

5 Read more

Determination of Moisture Content

Determination of Moisture Content

Preparing standards: the size (weight or volume, depending of the type of the equipment) of the standard must meet the recommendation of the manufacturer. Because the distribution of moisture in a sample is not uniform, the standard must be divided in several sub-samples which the weight of each of them fits with official recommendations. Moisture content is determined for each sub- sample. The mean of all values represents the standard. Then all sub-samples are bulked and kept in a sealed recipient to avoid uptake of water. Different standards, covering the range of the equipment must be prepared. Usually, in the case of hygrometers, manufacturers provide standards.
Show more

6 Read more

Influence of Moisture Content on Mechanical Properties of Autoclaved Aerated Concrete

Influence of Moisture Content on Mechanical Properties of Autoclaved Aerated Concrete

Figure 2 presented the stress-strain curves of specimens with different water content. Table 2 showed some basic mechanical parameters, including peak stress, peak strain, elastic modulus and residual strength under different water content. Test results in Figure 2 showed that the water content played a significant impact on the AAC stress-strain curve. With the increase of water content, the peak stress of AAC gradually decreased. When the water content was greater than 10%, each AAC specimen presented an obvious plastic compression process at the peak load stage, indicating that the strength of AAC decreased, the bearing capacity decreased, the failure form changed from brittleness to certain ductility, and the brittle failure of AAC was delayed.
Show more

6 Read more

Influence of Moisture Content to the Physical Properties of Unhusk Rice Grain

Influence of Moisture Content to the Physical Properties of Unhusk Rice Grain

Abstract— Determination physical properties of rice grain are important for design of harvesting, conveying and processing equipment. Size, sphericity, bulk density, a hundred grain seed mass, angle of repose and angle of friction against different surfaces were evaluated for five varieties of unhusk rice grain (Junjungan, Mundam, SokanPulau, Simaung and Bakwan) as a function of moisture content in the range of 9 to 25 (w.b.%). The objective of this study is to determine the influance of moisture content on the physical properties of local varieties of grain and rice from West Sumatra, Indonesia. Among the varieties, Junjungan had the highest values for geometric mean diameter, sphericity and thousand seed mass at all moisture levels. Geometric Mean Diameter (GMD) and sphericity increased significantly from 3.11 to 3.76 and 0.37 to 0.42 variety in a moisture content range of 9 to 25% w.b. Maximum values of bulk density and a thousand grain mass were obtained for Sokan Pulau (0.55-0.63g/cm3) and for Bakwan (29.99- 35.21 g). The angle of repose and angle of friction ranges for Mundam increased from 27.36 to 38.75˚and 27.33 to 37˚, respectively as increasing moisture content levels.
Show more

6 Read more

Studies on pre-treatment by compression for wood impregnation II: the impregnation of wood compressed at different moisture content conditions

Studies on pre-treatment by compression for wood impregnation II: the impregnation of wood compressed at different moisture content conditions

moisture content variation between individuals. The effects of moisture content on liquid uptake have been studied by Iida [2], but only on dry and wet conditions. A systematical study is needed to know the impregna- tion of wood pre-treated by compression at different moisture content (MC) conditions, because the impreg- nation treatment by compression method is most likely conducted at green condition due to the ease of compres- sion at this condition, as well as the ease of impregnation compared with the dried condition, whereas the pits are usually aspirated [3]. However, the MC at green condi- tion of different species and the MC at different period after falling down of the tree of the same species vary in a broad range. How the MC affects the impregnation after the pre-treatment by compression was still not clear. In
Show more

6 Read more

Validation of Prediction Models for Estimating the Moisture Content of Small Diameter Stem Wood

Validation of Prediction Models for Estimating the Moisture Content of Small Diameter Stem Wood

The validation results against the uncovered stem wood model are shown in Table 5 and Fig. 6. The difference between the measured and the modelled moisture content varied from 1 to 14% in 8 different piles. On average, the difference was 2.5%. The difference between the measured and the modelled value was not statistically significant (p=0.6). In this experiment, the age of the energy wood piles varied from 2–21 months. It can be seen that the oldest piles, which had been stored during the winter, have the highest difference between the modelled and the measured moisture content. The moisture content of energy wood increases during the winter, when the evaporation is really low, and in springtime melted snow increases the moisture of the pile especially in storage piles without a cover. It is a very site-specific situation, and it is hard to model how much the moisture increases, but the average amount of 5% has been used.
Show more

9 Read more

Show all 10000 documents...