Land Use Land Cover Dynamics on Sediment Yield Modeling of Angar Sub-Basin, Blue Nile Basin, Ethiopia
Miressa Bayisa,
Dereje Adeba
Issue:
Volume 10, Issue 4, July 2021
Pages:
62-74
Received:
19 July 2021
Accepted:
3 August 2021
Published:
26 August 2021
Abstract: The high land of Ethiopia is characterized as a region of high rates of land degradation and soil erosion, especially the Blue Nile Basin, where the eroded area is due to a significant change of land use/cover. This study aimed to estimate the sediment yield of Angar sub-basin using the Soil and Water Assessment Tool (SWAT) model interface of GIS at the outlet. The land use map of 1990, 2005, and 2018 was identified from TM, ETM+, and OLI_TIRS satellite images, and the accuracy was checked using the error matrix and Kappa statistic. The streamflow and sediment were calibrated and validated to check the model performance. The model performance has been evaluated using statistical parameters of coefficient of determination (R²) 0.75 to 0.94 for calibration & 0.77 to 0.95 for validation and Nash-Sutcliffe efficiency (NSE) 0.60 to 0.93 for calibration & 0.64 to 0.92 for validation. The annual average suspended sediment was 17.64 t/ha/yr. and the simulated annual average sediment yield was 18 t /ha/yr., 19 t/ha/yr. & 22 t/ha/yr. for land use of 1990, 2005, and 2018 respectively. The sediment severity percentage increased from land-use of 1990 to 2018 by 24.32%. due to the expansion of agricultural activities and settlement areas.
Abstract: The high land of Ethiopia is characterized as a region of high rates of land degradation and soil erosion, especially the Blue Nile Basin, where the eroded area is due to a significant change of land use/cover. This study aimed to estimate the sediment yield of Angar sub-basin using the Soil and Water Assessment Tool (SWAT) model interface of GIS a...
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Research and Demonstration of the Captive Flight Vibration of Certain Equipment
Shi Liuyang,
He GuangQiang
Issue:
Volume 10, Issue 4, July 2021
Pages:
75-78
Received:
2 September 2021
Accepted:
24 September 2021
Published:
29 September 2021
Abstract: The captive flight vibration is the main induced force environment encountered in the use of air-to-air missile, because of its high vibration intensity and long duration, which has a great impact on the structure and performance of the missile. The captive vibration of the missile is mainly caused by the aerodynamic disturbance around the missile. The captive vibration in the whole missile reliability test should adopt the broadband random vibration of 20 ~ 2000 Hz, and the vibration magnitude of the missile head should be 3 ~ 6 dB lower than that of the missile tail, so as to truly simulate the vibration effect caused by aerodynamic disturbance In this paper, according to the test conditions and calculation formula of airborne external captive flight vibration given in GJB150.16-2009, the power spectral density of captive flight vibration of this type of engine is obtained, and the characteristics and parameters of random vibration are analyzed. The formulas for calculating the power spectral density and the root mean square acceleration at the starting points of the ascending and descending sections corresponding to the slope of the random vibration test condition expressed by the octave are given. The practice shows that the laboratory test results using the research results are similar to those of the air hang flight test.
Abstract: The captive flight vibration is the main induced force environment encountered in the use of air-to-air missile, because of its high vibration intensity and long duration, which has a great impact on the structure and performance of the missile. The captive vibration of the missile is mainly caused by the aerodynamic disturbance around the missile....
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