Studies about the Influence Factors on Ultrasonic Velocity of Domestic Red Pine

2006 ◽  
Vol 321-323 ◽  
pp. 1177-1181 ◽  
Author(s):  
So Ra Han ◽  
Chun Young Park ◽  
Young Geun Eom ◽  
Jun Jae Lee
Keyword(s):  
Ultrasonic Velocity ◽  
Radial Direction ◽  
Influence Factors ◽  
Tangential Direction ◽  
Red Pine ◽  
Normal Wood ◽  
Reaction Wood ◽  
Decayed Wood ◽  
Effect Factors ◽  
Factors Influencing

This research was carried out to grasp the factors influencing to the ultrasonic velocity to improve the efficiency of the ultrasonic wave test using as the method of NDE of wood. However, it was difficult to detect the defect of wood accurately, because ultrasonic velocity is influenced by various factors. So, some effect factors, which were not concerned with decay, were confirmed at first. Therefore, in this research, we tried to find the factors which affect on the natural characters and the ultrasonic velocity at decayed wood, additionally, we tried an anatomic experiment and analyze. As a result of research, the velocity at radial direction was faster than that at tangential direction and the ultrasonic velocity at immature wood and reaction wood was slower than that at normal wood. And the ultrasonic velocity was more the slower at bigger the length of decay and reduction of weight.

scholarly journals Viscoelastic properties of green wood across the grain measured by harmonic tests in the range 0–95°C: Hardwood vs. softwood and normal wood vs. reaction wood

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 548-557 ◽  
Author(s):  
Vincent Placet ◽  
Joëlle Passard ◽  
Patrick Perré
Keyword(s):  
Storage Modulus ◽  
Viscoelastic Properties ◽  
Tension Wood ◽  
Radial Direction ◽  
Lignin Content ◽  
Softening Temperature ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Wood Compression

Abstract The viscoelastic properties of wood have been investigated with a dynamic mechanical analyser specifically developed for wooden materials, the WAVET device. Measurements were carried out on four wood species in the temperature range 0–100°C at frequencies varying between 5 mHz and 10 Hz. Wood samples were tested under water-saturated conditions in the radial and tangential directions. As expected, the radial direction always revealed a higher storage modulus than the tangential direction. Great differences were also observed in the loss factor. The tanδ peak and internal friction were higher in the tangential than in the radial direction. This behaviour is attributed to the fact that anatomical elements act as a function of the direction. The viscoelastic behaviour of reaction wood differs from that of normal or opposite wood. Compression wood of spruce, which has a higher lignin content, is denser and stiffer in transverse directions than normal wood, and has a lower softening temperature (T g). In tension wood, the G-layer is weakly attached to the rest of the wall layers. This may explain why the storage modulus and softening temperature of tension wood are lower than those for opposite wood. We also demonstrate that the time-temperature equivalence fits only around the transition region, i.e., between T g and T g+30°C. Apart from these regions, the response of wood reflects the combined effects of all its constitutive polymers, so that the equivalence is no longer valid.

Cell grouping and primary wall generations in the cambial zone, xylem, and phloem in Pinus

1968 ◽  
Vol 16 (2) ◽  
pp. 177 ◽  
Author(s):  
A Mahmood
Keyword(s):  
Cell Division ◽  
Mother Cell ◽  
Secondary Wall ◽  
Radial Direction ◽  
Cell Plate ◽  
Tangential Direction ◽  
Primary Wall ◽  
Photographic Evidence ◽  
Secondary Wall Deposition ◽  
Cambial Zone

The use of the term cambium, or equivalent terms, in modern literature is discussed. The term cambial zone adopted in this paper includes the cambial initial and the dividing and enlarging cells. The tissue mother cell produced at each division of the initial produces a group of four cells in xylem or two cells in phloem. Theoretical constructs have been made for xylem and phloem production by associating the concepts that xylem and phloem are produced in alternate series of initial divisions and that a new primary wall is deposited around each daughter protoplast at each cell division. Correlations are derived from the theoretical constructs for the thickness of primary wall layers lying in the tangential direction and of those lying in the radial direction at progressive histological levels. Deductions from theoretical constructs are made when the initial is producing xylem, when it changes its polarity from xylem to phloem production, and when the reverse change occurs. Most of the theoretical deductions are supported by photographic evidence. The chief point of this study is the demonstration of generations (multiplicity) of primary parental walls. The term intercellular material proposed in this paper includes the cell plate plus any remnants of ancestral primary walls between the current primary walls surrounding the adjacent protoplasts. This term is still applicable to cells where secondary wall deposition is taking place or has been completed.

The nature of reaction wood. IV. Variations in cell wall organization of tension wood fibres

1955 ◽  
Vol 3 (2) ◽  
pp. 177 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Wall ◽  
Degree Of Crystallinity ◽  
Tropical Species ◽  
Normal Wood ◽  
Reaction Wood ◽  
Gelatinous Layer ◽  
Wood Fibres ◽  
Cell Wall Organization

The cell wall organization, the cell wall texture, and the degree of lignification of tension wood fibres have been investigated in a wide variety of temperate and tropical species. Following earlier work describing the cell wall structure of tension wood fibres, two additional types of cell wall organization have been observed. In one of these, the inner thick "gelatinous" layer which is typical of tension wood fibres exists in addition to the normal three-layered structure of the secondary wall; in the other only the outer layer of the secondary wall and the thick gelatinous layer are present. In all the tension wood examined the micellar orientation in the inner gelatinous layer has been shown to be nearly axial and the cellulose of this layer found to be in a highly crystalline state. A general argument is presented as to the meaning of differences in the degree, of crystallinity of cellulose. The high degree of crystallinity of cellulose in tension wood as compared with normal wood is attributed to a greater degree of lateral order in the crystalline regions of tension wood, whereas the paracrystalline phase is similar in both cases. The degree of lignification in tension wood fibres has been shown to be extremely variable. However, where the degree of tension wood development is marked as revealed by the thickness of the gelatinous layer the lack of lignification is also most marked. Severity of tension wood formation and lack of lignification have also been correlated with the incidence of irreversible collapse in tension wood. Such collapse can occur even when no whole fibres are present, e.g. in thin cross sections. Microscopic examination of collapsed samples of tension wood has led to the conclusion that the appearance of collapse in specimens containing tendon wood can often be attributed in part to excessive shrinkage associated with the development of fissures between cells, although true collapse does also occur. Possible explanations of the irreversible shrinkage and collapse of tension wood fibres are advanced.

Einflussfaktoren in Routenzugsystemen*/Factors influencing internal milkrun systems - A method for calculating the intensity of influence of dimensioning parameters

2015 ◽  
Vol 105 (01-02) ◽  
pp. 65-71
Author(s):  
A. Martini ◽  
A. Rohe ◽  
U. Stache ◽  
F. Trenker
Keyword(s):  
Calculation Method ◽  
Influence Factors ◽  
Factors Influencing ◽  
Rank System ◽  
Factors Of Influence ◽  
Design Options ◽  
Specific Influence

Die Komplexität bei der Planung und Optimierung von Routenzugsystemen ist auf die Vielzahl der unterschiedlichen Gestaltungsmöglichkeiten und auf Interdependenzen zwischen den Einflussfaktoren zurückzuführen. Die im Fachartikel vorgestellte Verfahrensweise zur Einflussstärkenberechnung verschiedener Dimensionierungsparameter dient der Rangfolgebildung systemspezifischer Einflussfaktoren. Durch quantitativ-explorative Untersuchungen werden zudem Hypothesen für weitere Arbeiten gewonnen.   The complexity of planning and optimizing internal milkrun systems is a consequence of the multitude of different design options and interdependencies between the factors of influence. The calculation method for measuring the influence of different dimensioning parameters presented in this article serves to rank system-specific influence factors. Hypotheses for further research are obtained via quantitative-exploratory studies.

scholarly journals QUALITY OF REACTION WOOD IN Eucalyptus TREES TILTED BY WIND FOR PULP PRODUCTION

CERNE ◽  
2017 ◽  
Vol 23 (3) ◽  
pp. 291-297
Author(s):  
Walter Torezani Neto Boschetti ◽  
Juarez Benigno Paes ◽  
Graziela Baptista Vidaurre ◽  
Marina Donária Chaves Arantes ◽  
João Gabriel Missia da Silva
Keyword(s):  
Chemical Composition ◽  
Chemical Constituents ◽  
Wood Quality ◽  
Basic Density ◽  
Kraft Pulping ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Holocellulose Content

ABSTRACT This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by wind action. It also aims to explain the pulping parameters resultant from the quality of the wood. The trees were grouped into four tilt ranges, ranging from 0 to 50º, and the basic density, chemical composition of the wood, and performance in kraft pulping were assessed. Normal and tension wood had similar basic densities; while for opposite wood, the density was lower, being responsible for a decrease in reaction wood density. The chemical composition of the wood was influenced by the presence of reaction wood in the stem. Tension and opposite wood showed lower levels of extractives and lignin and higher holocellulose content when compared to normal wood, with favorable wood quality for pulping. The increase in holocellulose content and the reduction of lignin and extractives content contributed positively to a more delignified pulp and reduction of the Kappa number. However, after cooking the reaction wood under the same conditions as those of normal wood, reaction wood pulping tends to have a lower screen yields. Due to differences in basic density and chemical constituents between opposite and normal wood, it is recommended not to designate the opposite wood as normal wood.

scholarly journals Physical properties of sessile oak (quercus petraea l) used by the wood industry in Kosovo

2020 ◽  
Vol 2 (7) ◽  
pp. 278-285
Author(s):  
Rrahim Sejdiu ◽  
Florit Hoxha ◽  
Bujar Jashari ◽  
Lulzim Idrizi
Keyword(s):  
Specific Gravity ◽  
Moisture Content ◽  
Physical Properties ◽  
Radial Direction ◽  
Tangential Direction ◽  
Quercus Petraea ◽  
Sessile Oak ◽  
Content Ratio ◽  
Wet Condition ◽  
Shrinkage Coefficient

The paper shows some physical properties of sessile oak obtained in Kosovo regions. In the study are shown: wood shrinkage, specific gravity, shrinkage coefficient for 1% change of moisture content, ratio of shrinkage in tangential and radial direction etc. The amount of volumetric shrinkage of sessile oak is 15.95%, heartwood part has an average shrinkage 15.41% in The shrinkage of sapwood part is 17.56%. Specific gravity at: wet condition: (1.013gr/cm3); 12% (0.853gr/cm3) and 0% (0.826gr/cm3) of moisture content. Specific gravity of heartwood at: wet condition (1.05gr/cm3); 12% (0.88gr/cm3); 0% (0.85gr/cm3). The specific gravity of sapwood at: wet condition (0.91gr/cm3); 12% (0.77gr/cm3); 0% (0.748gr/cm3). The ratio of average shrinkage between tangential and radial cutting direction is 1.71%. This ratio was significantly higher in sapwood than heartwood. Coefficient of shrinkage (changing 1% of moisture content) in the radial direction is 0.00196, and 0.00323 in tangential direction.  

scholarly journals Analysis of factors influencing the complications of Solitaire AB stent mechanical thrombectomy in patients with acute intracranial artery occlusion

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Xin Zong ◽  
Jingmei Li ◽  
Shugai Liu ◽  
Qiuxia Liang ◽  
Xiaojun Luo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cerebral Hemorrhage ◽  
Mechanical Thrombectomy ◽  
Influence Factors ◽  
Artery Occlusion ◽  
Control Group ◽  
Intracranial Artery ◽  
Clinical Factors ◽  
Nihss Score ◽  
Factors Influencing

[Abstract] Objective: To investigate the influence factors of hemorrhage and stroke with retriever with Solitaire AB stent in patients with acute intracranial artery occlusion. Methods: A retrospective of 43 cases of patients with acute intracranial artery occlusion for endovascular treatment with Solitaire AB stent enrolled from March 2016 to June 2018 in our hospital, combining the characteristics of the patients of our city, through the clinical baseline data statistical analysis, complications screening of risk factors of complications. Results: There were 81.4% of patients who were dredged totally. The incidences of cerebral hemorrhage and infarction were 18.6% and 16.3%, cerebral hemorrhage group compared with control group, diabetes, blood pressure, revascularized time, NIHSS score, ASPECTS score had statistically significant differences, when infarction group compared with control group, age, opening time, ASITN_SIR score and grade of mTICI had statistically significant differences. Conclusion: Mechanical thrombectomy with Solitaire AB stent in patients with acute intracranial artery occlusion, the occurred of complications associated with various clinical factors, and the occurrence of complications seriously affect the prognosis of patients, therefore, selecting the indications strictly, and adopt individualized treatment to reduce complications.

ANATOMY AND CHEMICAL COMPOSITION OF LIRIODENDRON TULIPIFERA STEMS INCLINED AT DIFFERENT ANGLES

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 463-475 ◽  
Author(s):  
Tokiko Hiraiwa ◽  
Haruna Aiso ◽  
Futoshi Ishiguri ◽  
Yuya Takashima ◽  
Kazuya Iizuka ◽  
...  
Keyword(s):  
Lignin Content ◽  
Fibre Length ◽  
Liriodendron Tulipifera ◽  
Original Position ◽  
Chemical Characteristics ◽  
Normal Wood ◽  
Reaction Wood ◽  
Glucose Content ◽  
Wood Fibres ◽  
S2 Layer

The anatomical and chemical characteristics of reaction wood (RW) were investigated in Liriodendron tulipifera Linn. Stems of seedlings were artificially inclined at angles of 30 (RW-30), 50 (RW-50) and 70° (RW-70) from the vertical, and compared with normal wood (NW) from a vertical seedling stem. The smallest values for the wood fibre length and vessel number were observed in RW-50. The pit aperture angle was less than 10° in RW-30 and RW-50, in which reduced lignin content was observed in the S2 layer of the wood fibres. An increase in the glucose content and a decrease in the lignin and xylose content was observed in RW-50. The stem inclination angle affected the degree of RW development with regard to anatomical and chemical characteristics: the severest RW was observed in RW-50, followed by RW-30. RW-70 was similar in anatomical and chemical characteristics to NW, apparently because the inclination was too strong to enable recovery of its original position. In this case a vertical sprouting stem was formed to replace the inclined stem.

Material point method simulations of transverse fracture in wood with realistic morphologies

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 375-381 ◽  
Author(s):  
John A. Nairn
Keyword(s):  
Crack Propagation ◽  
Radial Direction ◽  
Material Point Method ◽  
Tangential Direction ◽  
Solid Wood ◽  
Material Point ◽  
Point Method ◽  
Complex Geometries ◽  
Transverse Fracture ◽  
Material Points

Abstract A new numerical method called the material point method (MPM) is well suited for modeling problems with complex geometries and with crack propagation in arbitrary directions. In this paper, these features of MPM were used to simulate transverse fracture in solid wood. The simulations were run on the scale of growth rings. The ease with which MPM handles complex geometries was helpful for modeling realistic morphologies of earlywood and latewood. Because MPM discretizes a body into material points, it was possible to go directly from a digital image of wood to a numerical model by assigning the location and properties of material points based on the intensity or color of pixels in an image. Because the description of cracks in MPM is meshless, it can handle a variety of crack propagation and direction criteria and can simulate complex crack paths that are a consequence of the morphology of the specimen. MPM simulations were run for cracks in the radial direction, the tangential direction, and at two angles to the radial direction. The specimens were loaded by axial displacement or by wedge opening. The MPM simulations fully included contact effects during wedge loading. Finally, the potential for coupling such simulations to new experiments as a tool for characterization of wood is discussed.

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