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Abstract

This article concerns the assessment of selected physical and mechanical properties of a dump soil. The dump soil is a specific soil with a very heterogeneous internal structure. Next to each other, there may be lumps and crumbs of cohesive soils mixed with non-cohesive soils accompanied by a very diverse admixture of organic substance. In addition, the soil in the waste dump, in spatial terms, may significantly differ in consistency and density. This is the result of the process of forming a dump soil, which takes place in three stages: excavation, transport and dumping. A heterogeneous soil deposited within the waste dump is subject to further processes: consolidation, compaction and creeping. Changes occurring in the course of these processes have a significant impact on the development of the properties of the dump soil.

Due to the large diversity of the tested soils, the results of their properties were divided into two groups, based on type and consistency of soil. This allows us to estimate the selected properties of the dump soil only on the basis of their macroscopic analysis.

Abstract

In this study, firstly, the behavior of a high steel frame equipped with tuned mass damper (TMD) due to several seismic records is investigated considering the structural and seismic uncertainties. Then, machine learning methods including artificial neural networks (ANN), decision tree (DT), Naïve Bayes (NB) and support vector machines (SVM) are used to predict the behavior of the structure. Results showed that among the machine learning models, SVM with Gaussian kernel has better performance since it is capable of predicting the drift of stories and the failure probability with R 2 value equal to 0.99. Furthermore, results of feature selection algorithms revealed that when using TMD in high steel structures, seismic uncertainties have greater influences on drift of stories in comparison with structural uncertainties. Findings of this study can be used in design and probabilistic analysis of high steel frames equipped with TMDs.

Abstract

This paper identifies the threats and risks of a terrorist attack on a critical infrastructure facility based on the example of Żelazny Most Tailings Storage Facility (OUOW). The threat analysis primarily took into account the threats of deliberate human actions. Identification of potential threats concerning the infrastructure surrounding the facility was conducted based on information that is readily available on the Internet. The reasons why it may be a potential target were also justified. Numerical calculations of the stress–deformation scale of the initial state of the reservoir, based on the Biot model with the Kelvin–Voight rheological skeleton, were presented as a starting point for in-depth research on the scale of threats and risks to the reservoir. The presented numerical model can be a starting point for calculating the stability of a reservoir subjected to explosives. The facility constitutes a major element of Lubińsko-Głogowski Okręg Miedziowy (Lubin-Głogów Copper District). OUOW Żelazny Most is the biggest such facility in Europe and is utilized to collect tailing waist. When expanded in its southern quarter, the facility will be the biggest in the world.

Abstract

Geogrids are widely used in civil engineering projects to reinforce road and railway structures. This paper presents research on the shearing strength of soil samples that have been reinforced with geogrids. The relationship between soil and geogrids is explored and evaluated by modeling the mechanical behavior of heterogeneous materials. For the purposes of this research, data obtained from tests of unreinforced sand samples with triaxial cells were compared with the data obtained from tests of reinforced sand samples. It was found that the shearing strength for reinforced samples was higher (from 9% to 49%) compared to unreinforced samples. Some damage to the geogrid was detected during the experiment, and for this reason, the same tests were numerically simulated for both unreinforced samples and samples reinforced with geogrids. Numerical simulations revealed the main reasons for damage to the geogrids during triaxial testing.

Abstract

The constantly growing, broadly understood, construction industry requires the use of a large amount of aggregates. The construction of roads, motorways, railway lines and hydrotechnical structures requires the use of aggregates of high quality, which is primarily determined by mechanical properties. The basic parameters describing mechanical properties of aggregates are the Los Angeles (LA) fragmentation resistance coefficient and the Micro-Deval (M DE) abrasion resistance coefficient. The LA and M DE coefficients depend mainly on the type of rock and its physical and mechanical properties. This has been thoroughly researched and documented as evidenced by the abundant literature in the field. However, the correlation between LA and M DE coefficients still gives rise to extensive discussions and some concerns. A number of publications demonstrate dependencies for various types of aggregates. Therefore, research was undertaken to present statistical analysis for one type of aggregate and one geological area.

This article presents the results of the fragmentation resistance test in the Los Angeles drum and the abrasion resistance test in the Micro-Deval drum of aggregates from Carpathian sandstone deposits. Aggregate samples were divided into three groups according to the location of the deposits and the tectonic unit from which they originated. The obtained results were subjected to static analysis to fit the best mathematical function describing the relationship between the two parameters.

Abstract

As the number of poorly soluble drugs is increasing, nanocrystals have become very interesting due to wide range of application possibilities. Curcuminwas used as a model active ingredient in this work. Even though it has many proven positive effects, due to its physicochemical issues, its possibilities have not been fully exploited. The goal of this work was to select optimal conditions for a top-down method for curcumin nanosuspension production, and to perform their comprehensive characterization applying complementary methodologies: dynamic light scattering, polarization and atomic force microscopy, thermal analysis, X-ray powder diffraction, antioxidant activity evaluation, release kinetics assessment, and screening of potential biological effects applying cell viability assays on normal human lung fibroblasts, human melanoma and human adenomacarcinoma cells. After 30 min of milling, nanosuspensions stabilized by polysorbate 80 and by its combinations with sucrose palmitate showed good stability, while curcumin crystal structure was unaltered. Obtained nanocrystals were well defined, with average diameter 120–170 nm and PDI of about 0.25, zeta potential was below −30 mV and pH~5 for all formulations. Nanodispersions exhibited high antioxidant potential and improved dissolution rate compared to the corresponding coarse dispersions. Although curcumin nanodispersions exhibited significant antiproliferative effect to each cancer cell line, the highest effect was towards adenocarcinoma cells.

Abstract

Investigation on current conduction mechanism through Tb and Mn codoped Bismuth Ferrite grafted polyvinyl alcohol (BTFMO-PVA) nanocomposite film above room temperature (300 K – 415 K) is reported here in detail. A detailed study on dielectric properties of the sample is done over a wide temperature range in a frequency range of 20 Hz - 2MHz. The conduction is attributed to correlated barrier hopping model. Bipolaron hopping dominates over single-polaron hopping in this system. Complex electric modulus spectra and complex modulus spectra are well explained by suitable models to understand the effective dielectric response. The sample responds to the externally applied magnetic field exhibiting negative magnetocapacitance at room temperature.

Abstract

The issue of the stratification of the underground subsoil is one of the principal geotechnical challenges. The development of the Cone Penetration Tests (CPTu) has resulted in the possibility to record parameters in a quasi-continuous way, which provides a very detailed description of the soil response. Such accurate measurements may therefore be treated as a signal or image and be analysed as such. This paper presents the application of high-pass spatial filters to perform soil stratification on the basis of the static penetration test. The presented algorithm has been tested on the test data set provided by the Organizers of TC304 Student Contest on Spatial Data Analysis (September 22, 2019, Hannover, Germany). It provides reasonable results at negligible computational cost and is applicable to most soils, especially if the contrast between the parameters of the adjacent layers is significant.

Abstract

Modification of poly-ether-ether-ketone (PEEK) to adapt to the biological properties of materials is currently the key point in the research of medical materials. The tribological properties and biocompatibility of the PEEK composites modified by carbon fiber (CF), potassium titanate whisker(PTW) and nano-particles were discussed in this paper. The results show the modified PEEK composites by a certain length to diameter ratio of CF show the best using effect in vivo experiments in good blood compatibility, which is suitable for orthopaedic implant materials. A large number of experiments show that the PEEK composites would be modified with a certain ratio of CF (about 30%wt.), whisker (about 15%wt.) and HA (about 5%wt.) particle with better biological tribological properties, more important value in medical research.