scholarly journals Análisis de los procesos de regresión y restitución del monumento natural Puente del Inca, Andes Centrales, Provincia de Mendoza, Argentina

2020 ◽  
Vol 47 (2) ◽  
pp. 446
Author(s):  
Esteban Lannutti ◽  
Maria Gabriela Lenzano ◽  
Jorge Baron ◽  
Marcelo Durand ◽  
Luis Lenzano
Keyword(s):  
Anthropogenic Factors ◽  
Thermal Waters ◽  
Heterogeneous Structure ◽  
The Finite Element Method ◽  
Resistant Material ◽  
Structural Regression ◽  
Natural Monument ◽  
The Stability ◽  
Natural And Anthropogenic Factors

The Puente del Inca, next to the homonymous village, is a natural bridge located on the Cuevas River, at about 2,700 m above sea level in the Central Andes of the province of Mendoza, Argentina. Declared Provincial Natural Monument in 2005, since the beginning of the 20th century it has registered a continuous weakening, mainly related to erosive processes that cause detachments of part of the material that makes up its structure. The objective of this study is to determine the factors involved in the structural regression and restitution of the natural bridge. To achieve this, visual inspection, characterization of thermal springs, measurement of accretion-erosion rate of travertine deposits, testing of materials and the development of a structural numerical model by the Finite Element Method, were carried out. Results indicate that the deterioration is linked, mainly, with changes in the geobiological system that regulates the travertine deposition and to the heterogeneous structure of the bridge. Changes of the geobiological system are related to the activity of the thermal waters present in the area, whose discontinuity and/or fluctuations in the flow rate are influenced by both natural and anthropogenic factors. The heterogeneity of the structure conditions the stability of the monument due to the presence of a less resistant material in the lower part of the bridge arch. From the numerical simulation, safety factors between 1.5 and 3 were determined for the bridge, thus, we conclude the structure is stable against its own weight, as long as the bridge maintains the current conditions.

scholarly journals Characterization of Functionally Graded Timoshenko Beams with Variable Rotational Speed

2019 ◽  
Vol 8 (4) ◽  
pp. 5926-5931
Keyword(s):  
Rotational Speed ◽  
Angular Speed ◽  
Functionally Graded ◽  
Timoshenko Beams ◽  
The Finite Element Method ◽  
Axial Loads ◽  
Fgm Beam ◽  
The Stability ◽  
Good Agreement

This paper investigates the free vibration characteristics and stability of a functionally graded Timoshenko beam spinning with variable angular speed. Material properties of the beam are assumed to be varied continuously along the thickness of the beam according to a power law and exponential law. The results show that increasing beam rotational speed increases fundamental mode frequency and the beam becomes more and more stable at higher speeds. This paper reports the dynamic behaviour of a rotating FGM beam subjected to axial periodic forces using the finite element method. The numerical results show good agreement with the reported beams models. Effects of static and time dependent components of axial loads on the stability of the FGM beam have been studied.

scholarly journals ЛІСІВНИЧО-ТАКСАЦІЙНІ ОСОБЛИВОСТІ ГРАБНЯКІВ ПРИРОДНОГО ЗАПОВІДНИКА «МЕДОБОРИ»

2020 ◽  
Vol 78 (4) ◽  
pp. 6-10
Author(s):  
U. O. Bachynska
Keyword(s):  
Age Groups ◽  
Anthropogenic Factors ◽  
Zonal Vegetation ◽  
Oak Trees ◽  
Different Types ◽  
Seed Origin ◽  
The Stability ◽  
The One ◽  
Natural And Anthropogenic Factors ◽  
L 13

In the Nature Reserve of Medobory a zonal vegetation is represented by dark deciduous forests, with a hornbeam and oak trees mainly, dominated by Quercus robur, Caprius betulus, and Flaxinus excelsior. Within the tree stands hornbeam predominates on the area of 21.7% of the forested lands of the reserve. Preliminary investigations of the Reserve hornbeam plantations were conducted by Mykola Korol and Ihor Humeniuk. They pointed to the stability of these plantations, their high competitive abilities but depleted biotic potential. The objects, selected for the study, are permanent trial areas, where during the last taxation measurements the hornbeam dominations in the tree stands were observed (with the tree stands of 6 and more items). On the studied trial areas mature and overmature plantations prevail by age groups. The hornbeams grow here mainly in young hornbeam forests in the first, second and third bonitets. The predominant number of trees on the trial areas is hornbeam of seed origin. Except L-28, where the conditions of growth are dry oakery on the rock, the hornbeams grow on the third bonitet and are of sprouting origin mainly. The tree stands on the trial areas are of the same age. As for the age groups they are mature and overmature, except for L-13 and L-28, where the young stocks grow, and L-13, where the one of a middle age grow. The tree stands taxation indicators on the trial areas are characterized by some differences, depending on age and completeness, within different types. The stock of live wood is on average 115-463 cubic metres per hectare. Trees differentiations by the degree of thickness show the process of a plant formation depending on their origin and age. On the trial areas the renewal of a hornbeam is represented by one- and two-years-old undergrowth. The forest stands are characterized by insignificant variability of their taxation structure indicators, being the result of a slight influence of natural and anthropogenic factors.

scholarly journals METHODOLOGICAL APPROACHES FOR ASSESSING THE IMPACT OF NATURAL AND ANTHROPOGENIC FACTORS ON RIVER GEOSYSTEMS

2021 ◽  
Vol 26 (2) ◽  
pp. 30-39
Author(s):  
N. E. Volkova ◽  
◽  
S. V. Podovalova ◽  
L. R. Umerova ◽  
◽  
...  
Keyword(s):  
Water Management ◽  
Water Resources ◽  
Water Resource ◽  
Anthropogenic Factors ◽  
Resource Potential ◽  
Rational Use ◽  
The Republic ◽  
The Stability ◽  
The Impact ◽  
Natural And Anthropogenic Factors

Introduction. The increasing shortage of water resources in the Republic of Crimea, due to water supplies from the external water source being shut off, emphasized the need to rationally use the existing water resource potential, which in turn requires a balance between the water users’ interests and maintaining a favorable environmental situation in the peninsula’s watercourses. Although in Russian and global practice there is a whole range of approaches to assessing the impact of natural and anthropogenic factors on the state of river geosystems, not all of them are applicable to solving the indicated problem. Methods. By testing integrated techniques, methods and models for assessing the impact of human activity on the stability of river natural and engineering systems (using the Zuya River as an example), we selected the most appropriate approach to develop viable solutions in water management. Results. By comparing the possibilities of using the scoring index method to assess the stability and vulnerability of watercourses to changes in physical and geographical as well as hydrological parameters and water quality, and methodology for the integrated assessment of the geoecological state of water resources of small rivers and the system model “Minor River Basin”, we revealed that only with the use of the latter it is possible not only to assess the real situation but also identify the reasons that impede the rational use of the peninsula’s watercourses. Conclusion. When developing decisions related to water management in the Republic of Crimea, the use of a suitable methodological approach to assessing the impact of natural and anthropogenic factors on the stability of river geosystems will make it possible to avoid mistakes when choosing measures and prioritizing actions aimed at the rational use of the existing water resource potential.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

Preparation and Characterization of β-glucosidase Films for Stabilization and Handling in Dry Configurations

2020 ◽  
Vol 21 (8) ◽  
pp. 741-747
Author(s):  
Liguang Zhang ◽  
Yanan Shen ◽  
Wenjing Lu ◽  
Lengqiu Guo ◽  
Min Xiang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Protein Function ◽  
Protein Stabilization ◽  
Functional Protein ◽  
Elongation At Break ◽  
Gelatin Films ◽  
The Stability ◽  
And Function ◽  
General Method

Background: Although the stability of proteins is of significance to maintain protein function for therapeutical applications, this remains a challenge. Herein, a general method of preserving protein stability and function was developed using gelatin films. Method: Enzymes immobilized onto films composed of gelatin and Ethylene Glycol (EG) were developed to study their ability to stabilize proteins. As a model functional protein, β-glucosidase was selected. The tensile properties, microstructure, and crystallization behavior of the gelatin films were assessed. Result: Our results indicated that film configurations can preserve the activity of β-glucosidase under rigorous conditions (75% relative humidity and 37°C for 47 days). In both control films and films containing 1.8 % β-glucosidase, tensile strength increased with increased EG content, whilst the elongation at break increased initially, then decreased over time. The presence of β-glucosidase had a negligible influence on tensile strength and elongation at break. Scanning electron-microscopy (SEM) revealed that with increasing EG content or decreasing enzyme concentrations, a denser microstructure was observed. Conclusion: In conclusion, the dry film is a promising candidate to maintain protein stabilization and handling. The configuration is convenient and cheap, and thus applicable to protein storage and transportation processes in the future.

scholarly journals Determination of Transverse Shear Stiffness of Sandwich Panels with a Corrugated Core by Numerical Homogenization

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1976
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski
Keyword(s):  
Transverse Shear ◽  
Shear Stiffness ◽  
The Finite Element Method ◽  
Homogenization Procedure ◽  
Plate Structures ◽  
Corrugated Board ◽  
Energy Equivalence ◽  
The Stability ◽  
Global Stiffness Matrix

Knowing the material properties of individual layers of the corrugated plate structures and the geometry of its cross-section, the effective material parameters of the equivalent plate can be calculated. This can be problematic, especially if the transverse shear stiffness is also necessary for the correct description of the equivalent plate performance. In this work, the method proposed by Biancolini is extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board. The method is based on the strain energy equivalence between the full numerical 3D model of the corrugated board and its Reissner-Mindlin flat plate representation. Shell finite elements were used in this study to accurately reflect the geometry of the corrugated board. In the method presented here, the finite element method is only used to compose the initial global stiffness matrix, which is then condensed and directly used in the homogenization procedure. The stability of the proposed method was tested for different variants of the selected representative volume elements. The obtained results are consistent with other technique already presented in the literature.

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