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The Impact of Coal Exploitation on Tidal Flat Changes, an Investigation Using Remote Sensing Data in Vietnam

Pham Thi Lan, Tong Si Son, Le Thi Thu Ha, Le Thi Le, Hoang Huu Duc

Inżynieria Mineralna

2021

no. 2

521--532

Tidal flat plays a crucial role in socio-economic development and ecological environment. Tidal flats in Ha Long-Cam Pha in Vietnam are impacted by human activities, especially coal mining activities. Using remote sensing data is able to detect, extract, and monitor the changes of tidal flats and exploited coal mine area with multi-temporal, in various scales, and for a large coverage. This study aims to investigate the impact of coal mining activities on the changes of tidal flats using remote sensing in Cam Pha, Ha Long, one of the biggest coal basins in Vietnam. Digital Elevation Models (DEMs) of tidal flats constructed by Landsat satellite images acquired in years 1989, 2001, and 2014 are compared to determine the volume changes. Besides, coal mining activities including coal production, waste rock dump area, and the expansion of open coal mine during the period 1989-2014 are investigated using correspondent Landsat images and the reports from the coal mine companies in the study area. Sediment samples in tidal flats are analyzed to determine the origin of the sediments. As the results, organic matter in the tidal flats is dominant with the concentration of 459 g/kg to 607 g/kg, which is evidence for the impact of coal exploitation on the coastal environment. In addition, the relationship between coal mine activities and tidal flat variation is well observed in this study.

The assessment of the electrohydraulic complex power controllability with different rates of closing pipeline valves

Kovalchuk Viktoriya, Korenkova Tetyana

Przegląd Elektrotechniczny

2020

R. 96, nr 12

234--237

It is shown that failure to observe the required rate of control of the pipeline shut-off and control equipment results in the occurrence of surges, breakdowns, breaks of the pipeline pressure systems, which is associated with a decrease in the controllability of the entire electrohydraulic complex. A mathematical model for the research of the energy processes in electrohydraulic complex with different closing rates of pipeline valves is proposed. It is proved that abrupt closure of the valve accompanied by a break of the pipeline, results in a complete loss of controllability in the hydraulic system. A mathematical and graphical formalization of power controllability based on the root-mean-square estimates of the harmonic power components is proposed.

W pracy pokazano, że kłopot w obserwacji wymaganego sposobu sterowania rurociągami i sterowanie wyposażeniem zespołu elektrohydraulicznego wynika z występowania przypływów, zatrzymań, zakłócenia ciśnienia w rurach, co jest skojarzone ze zmniejszeniem sterowności całego zespołu elektrohydraulicznego. Zaproponowano model matematyczny do badań procesów energetycznych w zespole elektrohydraulicznym różnymi sposobami zamykania zaworów. Wykazano, że nagłe zamknięcie zaworu towarzyszące uszkodzenie rurociągu prowadzi do całkowitej utraty sterowności systemu. Zaproponowano matematyczną i graficzną formalizację sterowności mocą, bazujące na ocenie błędu średnio-kwadratowego składników mocy.