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Review Article
New Developments and Future Prospects in the Solar Water Splitting
Alexander Axelevitch*
,
Sivan Marianna Tal-Mor
Issue:
Volume 14, Issue 1, February 2025
Pages:
1-12
Received:
20 December 2024
Accepted:
5 January 2025
Published:
22 January 2025
Abstract: Hydrogen is the material with the highest energy density. Therefore, we can consider it the fuel of the future. Methods of obtaining hydrogen in recent years have become the most important area of scientific research. Hydrogen production using solar energy is very important due to the absence of atmospheric pollution and environmental protection. In this article, we consider methods of obtaining hydrogen by water splitting on components using solar energy. With this goal, we consider a hydrogen fuel cell principle of operation and various methods for hydrogen production. The main attention is offered to the solar-powered water splitting driven by a photoelectrode reaction. We consider such methods as photoelectrochemical water splitting, photovoltaic electrolysis, and application plasmon-enhanced solar cells for the water splitting. The paper highlights advantages and disadvantages of different methods. According to our analysis, the further progress in the hydrogen production is based on application of nanotechnologies and plasmonic effects, which promise increasing of the water splitting efficiency. Advances in nanotechnology, including plasmon-enhanced materials and multi-junction photovoltaic cells, offer novel routes to higher efficiency and lower costs.
Abstract: Hydrogen is the material with the highest energy density. Therefore, we can consider it the fuel of the future. Methods of obtaining hydrogen in recent years have become the most important area of scientific research. Hydrogen production using solar energy is very important due to the absence of atmospheric pollution and environmental protection. I...
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Research Article
Stiffness Matrix for Bars with Variable Section or Inertia
Issue:
Volume 14, Issue 1, February 2025
Pages:
13-28
Received:
24 January 2025
Accepted:
12 February 2025
Published:
18 March 2025
Abstract: The matrix calculation by the Stiffness Matrix Method for structures composed of straight bars is normally performed considering the bars with constant section and inertia, and when the bars are of variable section, intermediate nodes are introduced, significantly increasing the size of the Stiffness Matrix. In this work, a generalization of the Stiffness Matrix Method for structures with bars of variable section and/or inertia is proposed, introducing adequate matrix coefficients for the calculation with bars with variable section and/or inertia, maintaining the number of nodes of the structure and therefore without increasing the size of the Stiffness Matrix. In practice, many structural systems are made up of bars of variable section or inertia, such as cartelized bars, cracked reinforced concrete bars, steel bars with semi-rigid joints or mixed concrete and steel bars. In all these cases, the result of the calculation when considering the constant section is, in general, approximate and must be interpreted taking into account the simplification introduced by the calculation, for example, in the calculation of deflections or deformations for concrete bars in a cracked state, which is the normal state in which they are found. In this case, the consideration of bars with a constant section yields results that are far from reality. And in other cases, something similar happens. Therefore, the generalization of the Stiffness Matrix Method for structures with variable section and/or inertia bars is really a refinement of the Stiffness Matrix calculation method that can be useful in many cases, and also provide results more in line with reality
Abstract: The matrix calculation by the Stiffness Matrix Method for structures composed of straight bars is normally performed considering the bars with constant section and inertia, and when the bars are of variable section, intermediate nodes are introduced, significantly increasing the size of the Stiffness Matrix. In this work, a generalization of the St...
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Research Article
Stiffness Matrix for Reinforced Concrete Bars of Variable Section and/or Inertia in Cracked State
Issue:
Volume 14, Issue 1, February 2025
Pages:
29-41
Received:
24 January 2025
Accepted:
12 February 2025
Published:
18 March 2025
Abstract: In volume I, the Stiffness Method has been developed for structures composed of straight bars of variable section and/or inertia, maintaining the number of nodes of the structure. In this Volume II, the method is developed for the case of reinforced concrete bars whose section is variable and which also work in a cracked state, which is their normal state under service conditions. By including the influence of cracking in the matrix calculation, bars with significantly lower stiffness result than for non-cracked bars, which influences the result of the matrix calculation. To carry out this study and define the influence of cracking on the coefficients of the Stiffness Matrix, it is necessary to know the reinforcements of the concrete bars, but these reinforcements depend on the result of the calculation, so it is a non-linear matrix system. The calculation is carried out in phases: first the elastic calculation without taking into account the cracking and then 4 calculation phases in the cracked state, each based on the previous result. In each phase, the required reinforcement is calculated, which is a piece of data for the next calculation phase. In this way, the cycle is repeated until the result coincides with the previous one so that the necessary reinforcements and the resulting actions maintain a minimum pre-established difference with respect to the previous ones. This approach is adjusted to the real behavior of cracked concrete bars and allows the values of the movements of the nodes of the structure to be determined more precisely, as well as the calculation of arrows of the bars.
Abstract: In volume I, the Stiffness Method has been developed for structures composed of straight bars of variable section and/or inertia, maintaining the number of nodes of the structure. In this Volume II, the method is developed for the case of reinforced concrete bars whose section is variable and which also work in a cracked state, which is their norma...
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