Wood Defects: Juvenile Wood and Growth Stresses
Young Heart Wood
A defect that occurs in wood from trees that have had a strong initial growth rate in diameter, as a result of having found very favorable ecological conditions or growing up in a forest of low mass density (low density of trees per hectare or defective). This rapid growth results in wood different from normal wood for a particular species, with the following characteristics:
- In the late wood, there was a lower proportion of cells with thick walls.
- From the foregoing feature, the apparent
Energy, Heat, and Temperature: Understanding the Basics
Energy
Energy is a physical quantity that represents the capacity of bodies to cause transformations in themselves or in other bodies.
Types of Energy
- Mechanical Energy: Possessed by bodies in motion (kinetic energy), those at a certain height (potential energy), or those that have experienced deformation (elastic energy).
- Electrical Energy: Possessed by electric current.
- Nuclear Energy: Produced in nuclear reactions of fusion and fission.
- Thermal Energy: Energy that flows from one body to another when
Understanding Environmental Issues: Causes, Effects, Solutions
Environmental Issues: Causes, Effects, and Solutions
We must be conscious of environmental problems such as overpopulation, deforestation, endangered species, pollution, hunting, and overfishing, because they contribute to global warming.
Deforestation and Its Impact
For instance, deforestation leads to the destruction of rainforests, wiping out many animals and fish. Rainforests help control global warming because they absorb carbon dioxide. In recent years, large areas have been destroyed as trees
Read MoreSubduction Zones and Plate Tectonics: Earth’s Dynamic Processes
Subduction Zones: Collision Between Plates
Subduction of Oceanic Lithosphere Under Oceanic Lithosphere
The result is the formation of a deep oceanic trench. When the subducting plate is partially melted in the mantle, magma originates. Part of it rises to the surface through cracks and reaches the subducted plate, forming an arched archipelago of islands with great volcanic activity.
Subduction of Oceanic Lithosphere Under Continental Lithosphere
This phenomenon produces an active continental margin
Read MorePlate Tectonics: Convection, Subduction, and Plate Dynamics
The Model of Convection
He believed that the mantle was smooth and capable of convection currents pushing from below the lithospheric plates, which float. The hot and less dense material of the lower mantle would rise to the surface areas of the lithosphere, and as the material cooled, it would sink back down to the mantle zone where it would heat up again. The areas where convection currents rise would coincide with the ridges, and the areas where they decrease would coincide with subduction zones.
Read MoreClassical Methods for Estimating Ore Reserves
The classical methods of estimating ore reserves are:
Arithmetic Average Method
The contours are plotted on the plans or vertical projection. The area defined is determined by a planimeter or other method. The average thickness is estimated by the simple or weighted arithmetic mean. The average content and the density are determined in the same way. The body part between the inner and outer contour is generally calculated independently because the resources of this area are reported in a lower category.
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