Search

Abstract Anthropogenic activity related to the extraction of gas and oil, raw materials or water pumping leads to slow or rapid ground deformation. The ground motion rate is related to the type of the mined material, geological conditions, mining methods and other factors. Ground subsidence resulting from the collapse of underground post-mining voids occurs gradually. Mining-induced earthquakes and seismic earthquakes are largely unpredictable and have an adverse impact on the local inhabitants and buildings. For this reason, monitoring of this phenomenon is a challenge. The application of interferometric SAR for the evaluation of ground movement has brought satisfactory results over the past twenty years mainly in the regions where no other measurements were conducted during ground subsidence. In this paper we have examined a mining-induced earthquake with a magnitude 4.5 which occurred in an underground copper ore mine in Poland on 29th November 2016 and caused eight fatalities. It also had an impact on ground surface deformation in the vicinity of the mine tailings. An assessment of the earthquake-related impact on surface movement was carried out by Sentinel-1 TOPS time series interferometry. The velocity of ground movement and the scale of the phenomenon were investigated. In addition, the impact of the mining-induced earthquake on Zelazny Most mine tailings site was analyzed. Moreover, the process of dynamic ground compaction was also investigated in detail. Ground movement following the mine earthquake was explored. Two time phases of the movements were determined. The first phase of dynamic ground displacement was rapid and 90% of total ground deformation appeared on the surface within 7 days. The second phase of displacement was a 'vanishing' one; it lasted for approx. 3 weeks and 10% of ground deformation appeared on the surface. The study revealed that the maximum observed ground subsidence did not exceed 9 cm. The presented results contribute to a better understanding of post-earthquake ground deformations in the light of their spatial distribution in time. Highlights • Sentinel-1 interferometry is used to assess subsidence caused by mining-induced earthquake (M W 4.5). • About 92% of total subsidence occurred within 48 h after mining-induced earthquake. • Substantial ground movement stopped 7 days after the earthquake (M W 4.5). • Contribution to studies on ground movements which result from mining-induced earthquake. [ABSTRACT FROM AUTHOR]

This paper deals with control strategies for discrete-time fractional multi-agent systems. By using the discrete fractional order operator we introduce memory effects to the considered problem. Necessary optimality conditions for discrete-time fractional optimal control problems with single- and double-summator dynamics are proved, and simulation results are presented. [ABSTRACT FROM AUTHOR]

Abstract: We study operators that are generalizations of the classical Riemann–Liouville fractional integral, and of the Riemann–Liouville and Caputo fractional derivatives. A useful formula relating the generalized fractional derivatives is proved, as well as three relations of fractional integration by parts that change the parameter set of the given operator into its dual. Such results are explored in the context of dynamic optimization, by considering problems of the calculus of variations with general fractional operators. Necessary optimality conditions of Euler–Lagrange type and natural boundary conditions for unconstrained and constrained problems are investigated. Interesting results are obtained even in the particular case when the generalized operators are reduced to be the standard fractional derivatives in the sense of Riemann–Liouville or Caputo. As an application we provide a class of variational problems with an arbitrary kernel that give answer to the important coherence embedding problem. Illustrative optimization problems are considered. [Copyright &y& Elsevier]

Abstract: This paper presents the Euler–Lagrange equations for fractional variational problems with multiple integrals. The fractional Noether-type theorem for conservative and nonconservative generalized physical systems is proved. Our approach uses well-known notion of the Riemann–Liouville fractional derivative. [Copyright &y& Elsevier]

Abstract: We introduce differential, integral, and variational delta embeddings. We prove that the integral delta embedding of the Euler–Lagrange equations and the variational delta embedding coincide on an arbitrary time scale. In particular, a new coherent embedding for the discrete calculus of variations that is compatible with the least-action principle is obtained. [Copyright &y& Elsevier]

Abstract: We prove the Euler–Lagrange delta-differential equations for problems of the calculus of variations on arbitrary time scales with delta-integral functionals depending on higher-order delta derivatives. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the necessary and sufficient optimality conditions for problems of the fractional calculus of variations with a Lagrangian depending on the free end-points. The fractional derivatives are defined in the sense of Caputo. [Copyright &y& Elsevier]

• Sinkholes pose significant hazards in populated areas. • We investigated early detection of sinkholes using Persistent Scatterer (PS) Interferometry. • Accelerating subsidence may indicate sinkhole occurence. Unexpectedly occurring sinkholes caused by shallow submerged voids are one of the key problems of intensively built-up post-mining areas. Five percent of Poland's territory is still under the influence of post-mining deformation. Impending sinkholes, which tend to develop randomly over very large areas, cannot be detected by using traditional geophysical methods. Moreover, geodetic measurement methods like Global Positioning System (GPS) analyses, tachymetry, laser scanning, or photogrammetry may be useful only for the registration of the dimensions and locations of sinkholes that have already occurred. Here, we investigate an area in Upper Silesia, Poland, where 345 sinkholes were recorded over a period of more than 20 years (1992–2013). Most of the events occurred in intensively built-up areas, and thus, these sinkholes posed a direct threat to the population. In the test area, 11 sinkholes were detected with a maximum depth of 16 m and maximum dimension of 25 m. The root cause of sinkhole formation was the collapse of post-mining shallow voids. We used satellite radar technology to detect and monitor ground movements potentially associated with the impending sinkholes. The findings showed that the application of Persistent Scatterer Interferometry can support the identification of zones where sinkholes will occur, given adequate spatio-temporal sampling. A stack of Envisat Synthetic Aperture Radar (SAR) images acquired between March 2003 and August 2010 was used in the analysis, and the results confirmed that precursory ground movements were detectable at an early stage of sinkhole development. The land subsidence rate observed prior to sinkhole collapse was not constant in time. Accelerated ground movements within 100 m of an observed sinkhole were detected. We conclude that satellite measurements may provide significant support in the early identification of areas prone to sinkhole occurrence. [ABSTRACT FROM AUTHOR]

Oil productions can result in pore pressure drop in the reservoir, generating an increase in effective stress and leading to reservoir compaction. The compaction in the subsurface reservoir translates to the earth's surface, which is manifested as a loss of elevation (land subsidence), causing damages to oil production facilities and surface infrastructures. The Liaohe oilfield, located in Liaohe River Delta (LRD), northeast of China, is one of the most significant subsidence areas in China as a direct consequence of oil extraction from the reservoir. Previous studies carried out in this area assumed the oil production-induced displacement retrieved from Interferometric Synthetic Aperture Radar (InSAR) corresponds only to vertical deformation. In this work, for the first time, we proposed a method to retrieve the full three-dimensional (3D) displacement field over the oilfield. We retrieved the vertical and east-west displacement components by combining the multiple-geometry InSAR line-of-sight (LOS) observations and retrieved the north-south component based on the assumption of a physical relationship between the horizontal and vertical displacement. Two ascending and two descending datasets from Sentinel-1 satellite covering the area were processed by an InSAR time series analysis over the 2017 to 2021 period, providing consistent displacement rate maps and displacement time series in the LOS direction. Spatial local-scale land subsidence was found in several producing fields over the deltaic region, including Shuguang, Huanxiling, and Jinzhou oilfields. The 3D displacement decomposition was then conducted in Shuguang oilfield. The derived 3D displacement field exhibit a circular subsidence bowl with a maximum subsiding rate reaching 212 mm/year, accompanied by a centripetal pattern of horizontal displacements with maximum rates up to 50–60 mm/year moving towards the subsidence center. The retrieved 3D displacements are in good agreement with predictions from the geomechanical modeling by assuming a disk-shaped reservoir subject to a uniform reduction in pore fluid pressure. Finally, we show the importance of knowing both the vertical and horizontal displacement in characterizing the lateral boundary of the subsurface reservoir. [ABSTRACT FROM AUTHOR]

The interaction between climate change and habitat fragmentation has been presented as a deadly anthropogenic cocktail. We cannot stop climate change, but it is within our circle of influence as ecologists to suggest landscape adaptation. Detailed population models that take into account climate change are considerably needed. We explore a detailed individual-based spatially explicit metapopulation model of a univoltine butterfly species where all processes are affected by daily weather, using historical daily weather data and future daily projections as input, in order to examine responses of a butterfly population in landscapes under various states of fragmentation and two climate change scenarios. This tool is used to investigate how landscapes could be adapted to compensate for possible negative impacts of climate change on population performance. We find that our model butterfly metapopulation was not only able to escape adverse conditions in summer by phenological shifts, but even to benefit from climatic warming. Varying either the amount of suitable habitat or patch size revealed a sharp threshold in population viability. In this particular case, however, the threshold was not affected by climate change and climate-dependent landscape adaptation was not required. The model presented here can be adapted for other species and applied to investigate scenarios for landscape adaptation. [Copyright &y& Elsevier]

Adsorption of bovine serum albumin (BSA) on the surface of SiO 2 was investigated mainly using quartz crystal microbalance (QCM) with energy dissipation mode. BSA adsorption kinetics and coverage were determined as a function of pH of the solution with the ionic strength of 1 × 10 −2 M. The maximum coverage was obtained in the pH range 4.5–5.4, near the protein isoelectric point. For pH larger than 5.4 and smaller than 4.5 a monotonic decrease of the adsorbed mass was observed. The images obtained using atomic force microscopy (AFM) method revealed various BSA structures depending on the pH at which they were adsorbed. The identified conformations were assigned to the compact triangular form with an effective length L ef = 8.3 nm and the elongated one with length L ef = 26.7 nm. The dependence between the structure of the protein layers formed on the surface and BSA conformations in solution was additionally followed by contact angle (CA) measurements. It turned out that CA values are very sensitive to the structure of BSA monolayers formed on the silica surface. Comparison of QCM and AFM data with those obtained by other indirect methods (CA) additionally enabled interpretation of the dependence of BSA adsorption on the pH of the solution. The obtained results confirmed the significant role of the highly anisotropic surface charge distribution of BSA molecules on the process of their adsorption. [ABSTRACT FROM AUTHOR]

Ultrathin “one-component” multilayer polymeric films for potential biomedical applications were designed based on polyvinyl alcohol,—a non-toxic, fully degradable synthetic polymer. Good uniformity of the obtained film and adequate adsorption properties of the polymeric layers were achieved by functional modification of the polymer, which involved synthesis of cationic and anionic derivatives. Synthesized polymers were characterized by FTIR, NMR spectroscopy, dynamic light scattering measurements and elemental analysis. The layer by layer assembly technique was used to build up a multilayer film and this process was followed using UV–Vis spectroscopy and ellipsometry. The morphology and thickness of the obtained multilayered film material was evaluated by atomic force microscopy (AFM). Preliminary studies on the application of the obtained multilayer film for coating of liposomal nanocarriers containing phenytoin, an antiarrhythmic drug, were performed. The coating effectively stabilizes liposomes and the effect increases with an increasing number of deposited layers until the polymeric film reaches the optimal thickness. The obtained release profiles suggest that bilayer-coated liposomes release phenytoin less rapidly than uncoated ones. The cytotoxicity studies performed for all obtained nanocarriers confirmed that none of them has negative effect on cell viability. All of the performed experiments suggest that liposomes coated with ultrathin film obtained from PVA derivatives can be attractive drug nanocarriers. [ABSTRACT FROM AUTHOR]