Open pit coal mining affects surrounding populated areas, resulting in terrain surface deformation. Surface deformation should be monitored as often as possible to control deformations and prevent potential incidents. This paper analyzes time series deformation estimated from the Sentinel-1 satellite images using the Persistent Scatterer Interferometry method to monitor subsidence rates caused by open pit mining activities. It is possible to measure deformations using classical geodetic methods, but those are rarely used in practice because they are time-consuming and expensive for application in large areas. Using the open access radar images from the Sentinel-1 mission, 513 images from the repository were downloaded between October 2016 and the end of December 2020. We present the processing steps in detail in order to establish a workflow for the automated processing of vertical displacement estimation using open source tools; a total of 402 images were processed: 215 images belonged to the ascending satellite orbit, 187 images belonged to the descending orbit, and 111 images were rejected because of adverse weather conditions. The PS InSAR technique has never been used for the mines of the Republic of Serbia or for land surveying practices related to deformation monitoring. The results based on the Sentinel-1 images were compared with results from geodetic leveling and with neotectonic uplift trends. The trend lines of vertical displacement obtained from PS and corresponding leveling are significantly similar (a Pearson correlation of 85% with a p-value of 0.015). The final evaluation reported results of vertical displacements at the leveling benchmark of −3.4 mm/year with the PS InSAR method and −2.7 mm/year with the leveling method. A comparison of the PS vertical displacements with a settlement model fits reasonably, suggesting that the measurements are valid. As four years of PS time series data is insufficient to establish undisputable conclusions on the neotectonics uplift, extending the time series (covering at least a decade) implies that this approach will become attractive in future neotectonic uplift trend estimations. This study illustrates not only the ability of Sentinel-1 data in mapping vertical deformations, but the obtained results could also be used for geohazard monitoring and land monitoring in general for the area of interest.
The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA) in measuring carotid artery wall thickness (CAWT) and color Doppler ultrasound (CD-US) in measuring intimae-media thickness (IMT). Eighty-nine patients (aged 35–81) were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data were described as the mean value ± standard deviation, and were compared using the Mann–Whitney U test. A p value <0.05 was considered significant. Bland–Altman statistics were employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.62 to 1.60 mm, with a mean value of 1.09 mm. IMT ranged from 0.60 to 1.55 mm, with a mean value of 1.06 mm. We observed an excellent agreement between CD-US and MDCTA in the evaluation of the common carotid artery thickness, with a bias between methods of 0.029 mm (which is a highly statistically important difference of absolute values [t = 43.289; p < 0.01] obtained by paired T test), and limits of agreement from 0.04 to 0.104. Pearson correlation coefficient was 0.9997 (95% CI 0.9996–0.9998; p < 0.01). We conclude that there is an excellent correlation between CAWT and IMT measurements obtained with the MDCTA and CD-US.
The interaction between the wheel and the running rails within the railway system introduces intricate stress patterns, resulting in the formation of rolling contact fatigue (RCF) rail defects. The magnitude of this stress is contingent upon factors such as track performance, vehicle characteristics, and service conditions. While advancements in rail metallurgy can mitigate the issue to some extent, no economically viable steel composition currently exists that can completely withstand the repetitive stresses associated with RCF. It is more cost-effective to properly maintain rails for longer use rather than replace them entirely. The paper emphasizes the importance of classifying and coding RCF rail defects in light of their potential adverse effects on rail transport safety. It provides an analysis of the available inspection methods for RCF rail defects and recommends the ones that should be implemented on the Serbian railway network. A combination of proposed inspection methods is preferred to increase detection efficiency for different types of RCF defects.
Rail defects due to the rolling contact fatigue have a significant place in the Handbook of Rail Defects in the framework of UIC Code 712 in 2002. The paper presents the system for coding and classification of rail defects according to UIC recommendation IRS 70712 in 2018. The presented classification does not cover all known defects due to the rolling contact fatigue (e.g. stud and belgrospi defects). It is recommended that Infrastructure Manager should supplement the Handbook of Rail Defects with the types of defects noticed on its railway network. The authors recommend information that should be included in the database of rail defects, in order to monitor the development of defects, taken measures and their efficiency, as well as to enable the exchange of statistical data on rail defects at the international level.
Uloga kanalizacionih sistema je da bezbedno sprovode upotrebljene i atmosferske vode sa urbanih slivova, bez prekida u radu. Jedan od pristupa koji se razvija poslednjih godina, a koji potencijalno može značajno da unapredi rad ovih sistema je primena digitalnih blizanaca. Sastavni element digitalnih blizanaca je i adekvatno prostorno raspoređena senzorska mreža, koja omogućava praćenje merodavnih hidrauličkih veličina u realnom vremenu. Nažalost, imajući u vidu specifičnosti rada ovih sistema i visoku cenu profesionalne merne opreme, najčešće ovakvih senzora nema dovoljno. U ovom radu je dat osvrt na specifičnosti mernih metoda koje se koriste u kanalizacionim sistemima. Analizirana su i alternativna rešenja u vidu pristupačnih senzora, gde je posebno apostrofirano rešenje koje se razvija na Institutu za hidrotehniku koje se bazira na primeni videometrijskih metoda. Taksativno su navedeni i posebni uslovi koja sva merna oprema koja se koristi u kanalizaciji, mora da zadovolji.