scholarly journals Progress of spreading Stereum sanguinolentum (Alb. et Schw.: Fr.) Fr. wound rot and its impact on the stability of spruce stands

2012 ◽  
Vol 50 (No. 8) ◽  
pp. 360-365 ◽  
Author(s):  
P. Čermák ◽  
L. Jankovský ◽  
J. Glogar
Keyword(s):  
Mechanical Stability ◽  
Average Rate ◽  
Stem Length ◽  
Stand Age ◽  
Bark Stripping ◽  
Adaptation Potential ◽  
Sample Tree ◽  
Spruce Stands ◽  
The Stability ◽  
Forest District

  In 2002–2003, we conducted a detailed inventory of bark stripping damage in Forest District (FD) Mořkov (Forest Enterprise Frýdek-Místek) and in Forest Range (FR) Proklest (Training Forest Enterprise Křtiny). In total, 3,988 trees were examined in FD Mořkov and 1,512 trees in FR Proklest; in detail, 52 and 38 sample trees in FD Mořkov and FR Proklest, respectively. The rot spread in stems in the Proklest RD by an average rate of 15.6 cm/year, in FD Mořkov by an average rate of 23.8 cm/year. The rate of the rot spread decreases with the increasing period of parasitizing. The stem length affected by the rot ranged most frequently between 2.5 and 4.5 m (Proklest) or 2 and 3 m (Mořkov). The rot damaged on average 38.8 and 42.4% of the sample tree volume in RD Proklest and FD Mořkov, respectively. The proportion of trees affected by the rot decreased with the stand age. The observed extent of wound rot significantly decreases mechanical stability of stands and their adaptation potential.

scholarly journals Damage by deer barking and browsing and subsequent rots in Norway spruce stands of Forest Range MoP.

2012 ◽  
Vol 50 (No. 1) ◽  
pp. 24-30 ◽  
Author(s):  
Čermák ◽  
J. Glogar ◽  
L. Jankovský
Keyword(s):  
Norway Spruce ◽  
Red Deer ◽  
Financial Loss ◽  
Bark Stripping ◽  
Age Class ◽  
Spruce Stands ◽  
Financial Losses ◽  
Forest District ◽  
Extensive Damage

The paper deals with the determination of the rate of damage by deer barking and browsing, the subsequent rot caused by Stereum sanguinolentum and the rate of its progress, elucidates causes of damage and quantifies volume and financial losses in the region of Forest Range Mořkov, Forest District Fren&scaron;t&aacute;t pod Radho&scaron;těm. In the most damaged 2<sup>nd</sup> age class, decay by Stereum sanguinolentum was recorded in 59% of damaged trees. The progress of rot ranged from 1 to 70 cm/year. The high number of red deer is considered to be the main reason of extensive damage by bark stripping in the Forest Range Mořkov. The actual financial loss caused by depreciation of wood by the rot is greatest in the 5<sup>th</sup> age class amounting to CZK 64,320 per ha.

scholarly journals The effect of root rot and bark-stripping on wind stability of Norway spruce (Picea abies (L.) H. Karst.) = Parastās egles (Picea abies (L.) H. Karst.) vēja noturības izmaiņas sakņu trupes un stumbra mizas bojājumu ietekmē

2020 ◽  
Author(s):  
◽  
Oskars Krisans ◽  
Keyword(s):  
Climate Change ◽  
Picea Abies ◽  
Norway Spruce ◽  
Root Rot ◽  
Mechanical Stability ◽  
Stem Volume ◽  
Natural Disturbances ◽  
Bark Stripping ◽  
Secondary Failure ◽  
Spruce Stands

Climate change causes gradual decline of economic value of Norway spruce forestry except in boreal and hemiboreal forest zones that will remain suitable for this tree species. However, also in this region frequency and scale of damages caused by natural disturbances (abiotic and biotic factors) are expected to increase. Norway spruce will remain its economic significance and role in carbon sequestration in Latvia, if forest management practices will be changed to prevent or minimize the damages caused by natural disturbances. Information on effect of natural disturbances and their interactions on trees is vital for development of recommendations for adaptation of forestry to climate change. The aim of the thesis is to assess the effect of root rot and bark-stripping on possibility of wind induced damages in Norway spruce stands. Tree mechanical stability was primarily determined by its stem volume; however, the presence of damages, caused by biotic agents, such as root rot and bark-stripping, significantly reduced it. Morphometric parameters of Norway spruce stem and root plate differed significantly between stands on drained peat and mineral soils. Root-rot notably and significantly affected mechanical stability of trees regardless of soil type and volume of root-soil plate, resulting in similar reduction of wind load necessary to cause both primary and secondary failure. Consequences of bark-stripping primarily affected root-soil anchorage, more commonly causing uprooting than stem fracture. Most pronounced was reduction of resistance against primary failure. Changing wind climate, high population density of cervids and presence of root-rot will lead to increased risk of damages caused by (repeated) storms and subsequent legacy effects. The survival of forest stands depends on dimensions of trees and exposure time to different damaging agents, and, at current climate and silvicultural practice, was significantly reduced when transitioning into third age class (41-60 years). Targeted forestry, ensuring planting of improved material, lower initial density, timely precommercial thinning and thus ensuring faster reach of the tree dimension required for final harvest will reduce the time when stands are subjected to significant wind damage risk, thus minimizing the possibility of such disturbance and boosting value of Norway spruce stands.

Mechanical stability of black spruce in the clay belt region of northern Ontario

1987 ◽  
Vol 17 (9) ◽  
pp. 1080-1091 ◽  
Author(s):  
V. G. Smith ◽  
M. Watts ◽  
D. F. James
Keyword(s):  
Mechanical Stability ◽  
Black Spruce ◽  
Stand Density ◽  
Tree Height ◽  
Static Force ◽  
Northern Ontario ◽  
Wind Speeds ◽  
Spruce Stands ◽  
Stand Height ◽  
The Stability

Black spruce (Piceamariana (Mill.) B.S.P.) is an important pulpwood species that grows on peatland sites in the clay belt region of northern Ontario. The mechanical stability of spruce found on these sites is crucial in determining how tall a stand can grow before losses due to windthrow become excessive. In this study, the stability of a sample of 58 black spruce trees, in stands of various height and density classes, was measured by winching them over and determining their critical turning moment. Regression analysis was used to express critical turning moment as a function of tree height, dominant stand height, and stand stocking. An analysis was carried out to estimate turning moments due to static wind action on the sample trees and predicting the wind speeds required to produce the static force needed to cause windthrow. A comparison of the measured critical turning moments to the estimated wind-generated critical turning moments was used to identify the wind speeds that have enough static force to cause windthrow. A table of critical wind speeds, based on a reference wind, is given for black spruce stands of various heights and densities. Based on these wind speeds and winds associated with periodic storms, black spruce stands can be expected to become susceptible to windthrow once dominant stand height reaches 20 to 21 m. Stand stability increases with stand density owing to the greater ability of dense stands to dissipate incoming winds and the added stability of interlocking root systems. These results suggest that the black spruce stands growing on peatland sites in the clay belt should be harvested before dominant stand height reaches a maximum of 20 to 21 m to avoid excessive losses due to windthrow.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

Temperature-Dependent Mechanical Stability of Retained Austenite in Thermomechanically Processed 3Mn Steel

2021 ◽  
Vol 1016 ◽  
pp. 762-767
Author(s):  
Aleksandra Kozłowska ◽  
Adam Grajcar ◽  
Aleksandra Janik ◽  
Krzysztof Radwański
Keyword(s):  
Retained Austenite ◽  
Mechanical Stability ◽  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Trip Effect ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Static Tensile ◽  
The Stability ◽  
Backscatter Diffraction

The temperature-dependent mechanical stability of retained austenite in medium-Mn transformation induced plasticity 0.17C-3.3Mn-1.6Al-1.7Al-0.22Si-0.23Mo thermomechanically processed steel was investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) methods. Specimens were deformed up to rupture in static tensile tests in a temperature range 20–200°C. It was found that deformation temperature affects significantly the intensity of TRIP effect. In case of specimens deformed at temperatures higher than 60°C, a gradual temperature-related decrease in the stability of γ phase was noted. It indicates a progressive decrease of the significance of the TRIP effect and at the same time the growing importance of the thermally activated processes affecting a thermal stability of retained austenite.

scholarly journals Longitudinal Tension and Mechanical Stability of a Pressurized Straw Tube

Instruments ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 27
Author(s):  
Levan Glonti ◽  
Temur Enik ◽  
Vladimir Kekelidze ◽  
Alexander Kolesnikov ◽  
Dmitry Madigozhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Charged Particle ◽  
Measurement Technique ◽  
Mechanical Stability ◽  
Stability Conditions ◽  
Particle Detectors ◽  
Straw Tube ◽  
Special Measurement ◽  
The Stability ◽  
Tube Study

For the development of charged particle detectors based on straw tubes operating in vacuum, a special measurement technique is required for the evaluation of their mechanical properties. A summary of the known equations that govern straw behavior under internal pressure is provided, and a new experimental method of a strained pressurized straw tube study is presented in this paper. The Poisson’s ratio of the straw wall, which defines the stability conditions of a built-in tube, was measured for the NA62 spectrometer straw, and its minimum pre-tension was estimated.

The Stability of Veins Under Torsion

2012 ◽  
Author(s):  
Justin R. Garcia ◽  
Hai-Chao Han
Keyword(s):  
Diabetes Mellitus ◽  
Health Risks ◽  
Mechanical Stability ◽  
Thrombus Formation ◽  
Body Movement ◽  
Critical Value ◽  
The Body ◽  
Clinical Interest ◽  
The Stability

Twisted veins are observed throughout the body and are often associated with health risks such as hypertension and diabetes mellitus [1]. Recently, it has been shown that veins will buckle and become tortuous when lumen pressure exceeds a critical value [2]. However, veins also undergo twist deformations in vivo due to body movement, vein grafting, and microanastomosis procedures which may lead to reduced patency, kinking, and thrombus formation [3, 4]. In spite of this, little data is available regarding the stability of veins when subject to twist deformations. Therefore, it is of clinical interest to investigate the mechanical stability of veins under torsion.

Mechanical stability of a class of regular thin-shell wormholes

2020 ◽  
Vol 35 (37) ◽  
pp. 2050309
Author(s):  
Faisal Javed ◽  
M. Sharif
Keyword(s):  
Thin Shell ◽  
Mechanical Stability ◽  
Static Solution ◽  
Stable Region ◽  
Stable Configuration ◽  
Energy Tensor ◽  
Radial Perturbation ◽  
Stress Energy ◽  
Thin Shell Wormholes ◽  
The Stability

This paper explores the stable configuration of thin-shell wormholes constructed from two regular black holes (modified Hayward and four parametric) by using Visser cut and paste approach. The components of stress-energy tensor are evaluated through the Lanczos equations. We analyze the stability of thin-shell by using radial perturbation preserving its symmetries about equilibrium static solution. It is found that modified Hayward wormholes are more stable than the Hayward wormholes. Further, the stable regions of four parametric regular wormholes are larger than the Schwarzschild, Reissner–Nordström and Ayón–Beato–García wormholes. We conclude that stable region decreases for highly charged thin-shell wormholes.

scholarly journals Direct link between mechanical stability in gels and percolation of isostatic particles

2019 ◽  
Vol 5 (5) ◽  
pp. eaav6090 ◽  
Author(s):  
Hideyo Tsurusawa ◽  
Mathieu Leocmach ◽  
John Russo ◽  
Hajime Tanaka
Keyword(s):  
Mechanical Stability ◽  
Construction Materials ◽  
Separation Process ◽  
Medical Applications ◽  
Colloidal Gels ◽  
Direct Link ◽  
Equilibrium Thermodynamic ◽  
Phase Separation Process ◽  
Long Time ◽  
The Stability

Colloidal gels have unique mechanical and transport properties that stem from their bicontinuous nature, in which a colloidal network is intertwined with a viscous solvent, and have found numerous applications in foods, cosmetics, and construction materials and for medical applications, such as cartilage replacements. So far, our understanding of the process of colloidal gelation is limited to long-time dynamical effects, where gelation is viewed as a phase separation process interrupted by the glass transition. However, this purely out-of-equilibrium thermodynamic picture does not address the emergence of mechanical stability. With confocal microscopy experiments, we reveal that mechanical metastability is reached only after isotropic percolation of locally isostatic environments, establishing a direct link between the load-bearing ability of gels and the isostaticity condition. Our work suggests an operative description of gels based on mechanical equilibrium and isostaticity, providing the physical basis for the stability and rheology of these materials.

scholarly journals Electrophoretic Deposition of Copper(II)–Chitosan Complexes for Antibacterial Coatings

2020 ◽  
Vol 21 (7) ◽  
pp. 2637 ◽  
Author(s):  
Muhammad Asim Akhtar ◽  
Kanwal Ilyas ◽  
Ivo Dlouhý ◽  
Filip Siska ◽  
Aldo R. Boccaccini
Keyword(s):  
Electrophoretic Deposition ◽  
Mechanical Stability ◽  
Metallic Copper ◽  
Antibacterial Properties ◽  
Threshold Concentration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Antibacterial Coatings ◽  
Elemental Analyses ◽  
The Stability

Bacterial infection associated with medical implants is a major threat to healthcare. This work reports the fabrication of Copper(II)–Chitosan (Cu(II)–CS) complex coatings deposited by electrophoretic deposition (EPD) as potential antibacterial candidate to combat microorganisms to reduce implant related infections. The successful deposition of Cu(II)–CS complex coatings on stainless steel was confirmed by physicochemical characterizations. Morphological and elemental analyses by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy verified the uniform distribution of copper in the Chitosan (CS) matrix. Moreover, homogeneous coatings without precipitation of metallic copper were confirmed by X-ray diffraction (XRD) spectroscopy and SEM micrographs. Controlled swelling behavior depicted the chelation of copper with polysaccharide chains that is key to the stability of Cu(II)–CS coatings. All investigated systems exhibited stable degradation rate in phosphate buffered saline (PBS)–lysozyme solution within seven days of incubation. The coatings presented higher mechanical properties with the increase in Cu(II) concentration. The crack-free coatings showed mildly hydrophobic behavior. Antibacterial assays were performed using both Gram-positive and Gram-negative bacteria. Outstanding antibacterial properties of the coatings were confirmed. After 24 h of incubation, cell studies of coatings confirms that up to a certain threshold concentration of Cu(II) were not cytotoxic to human osteoblast-like cells. Overall, our results show that uniform and homogeneous Cu(II)–CS coatings with good antibacterial and enhanced mechanical stability could be successfully deposited by EPD. Such antibiotic-free antibacterial coatings are potential candidates for biomedical implants.

Sign in / Sign up

Export Citation Format

Share Document