Title: |
Assessment of Stand Structure Characteristics in Forest Compartments Containing Cinnamomum Balansae in Ta Dung National Park, Dak Nong Province, Viet Nam |
Authors: |
Phan Thi Hang, Nguyen Thi Thanh Huong, Nguyen Thi Thu |
Source: |
International Journal of Latest Engineering Research and Applications, pp 01 - 12, Vol 10 - No. 03, 2025 |
Abstract: |
Understanding forest structure is essential for sustainable forest management, particularly in the context of climate change and increasing anthropogenic pressures. This study aims to analyze the stand structure and biodiversity characteristics of forest communities with the presence of Cinnamomum balansaein Ta Dung National Park, Vietnam. A total of 50 sampling plots (900 m² each, 30 × 30 m) were surveyed, and data were analyzed using RStudio 4.4.0.Results indicate that Cinnamomum balansaeis among the 10 species with the highest Importance Value Index (IVI%), reflecting its significant ecological role in the studied forest stand. Biodiversity indices (Margalef, Shannon-Wiener, Simpson) revealed a highly stable community structure, with Simpson’s index (D = 0.98) indicating no single species dominance. Diameter distribution exhibited a reverse J-shaped curve, with small-diameter trees (6–10 cm DBH) dominating, characteristic of an uneven-aged forest with active natural regeneration. Similarly, height distribution analysis showed that medium-height trees (8–16 m) accounted for the largest proportion, suggesting that the forest is in a regeneration and recovery phase. These findings provide crucial scientific insights for sustainable forest management and biodiversity conservation, especially in developing climate-resilient forest policies. Future research should focus on the role of large trees in carbon sequestration, the impact of climate change on forest dynamics, and the application of remote sensing technologies in long-term forest monitoring. |
Keywords: |
IVI%, N/D, N/H, R Studio, Biodiversity indices, Ta dung National Park |
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DOI: |
10.56581/IJLERA.10.3.01-12 |
Title: |
Sum of Secondary Orthogonal Bimatrices in Rnxn |
Authors: |
Dr. R. Surendar, M. Muthulakshmi |
Source: |
International Journal of Latest Engineering Research and Applications, pp 13 - 18, Vol 10 - No. 03, 2025 |
Abstract: |
Let 𝐹∈ {𝑅,𝐶,𝐻}. Let 𝓤𝒏×𝒏 be the set of secondary unitary bimatrics in 𝐹𝒏×𝒏, and let 𝑂𝒏×𝒏 be the set of secondary orthogonal bimatrices in 𝐹𝒏×𝒏. Suppose 𝑛≥2, we show that every 𝐴𝐵∈ 𝐹𝒏×𝒏 can be written as a sum of bimatrices in 𝓤𝒏×𝒏 and of bimatrices in 𝑂𝒏×𝒏. let 𝐴𝐵∈ 𝐹𝒏×𝒏 be given that and let 𝑘≥2 be the least integer that is a least upper bound of the singular values of AB. When F=R, we show that if 𝑘≤3, then AB can be written as a sum of 6 secondary orthogonal bimatrices; if 𝑘≥4, we show that AB can be written as a sum of 𝑘+2 secondary orthogonal bimatrices. |
Keywords: |
Orthogonal matrix, unitary matrix, bimatrix, orthogonal bimatrix, unitary bimatrix, secondary orthogonal bimatrices, secondary unitary bimatrices. |
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DOI: |
10.56581/IJLERA.10.3.13-18 |
Title: |
Seismic and Induction Transducers, Misaligment |
Authors: |
P. Fraga, B. F. De Cal, B. |
Source: |
International Journal of Latest Engineering Research and Applications, pp 19 - 31, Vol 10 - No. 03, 2025 |
Abstract: |
This paper presents a successful application, among many others, of industrial mechatronics on the quality and proper functioning of rotating machines. The misalignment is the most common latent anomaly in a rotating system after imbalance, so this phenomenon is chosen. The information that a seismic transducer can give of the vibration of a rotor is compared with that provided by the installation of two induction transducers or proximity, located in transverse planes at 90º, which not only reproduce a high vibration alarm, but also provide important information about the causes. This study has been carried out in a laboratory rotor, causing the phenomenon of misalignment. Latent misalignment is therefore very dangerous, because the cyclic charges can produce microscopic surface discontinuities that act as tension concentrated, and therefore, as nucleation sites of cracks. Subsequently, a radial load will be introduced which and increased in progressive values to simulate the load that the misalignment would produce, and thus the vibration propagation will be observed, comparing seismic and proximity transducer data. |
Keywords: |
Rotor dynamics, vibration, misalignment, seismic and proximity transducers. |
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