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1

Excavations in the vicinity of the antiflood embankments – calculating issues

Grodecki Michał

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 2

138--147

EN

According to Polish law, it is prohibited to perform excavations or locate buildings closer than 50 m from the embankment. In order to obtain exemption from this ban, filtration and stability analysis of the embankment and excavation in the flood conditions have to be performed. This paper presents results of the numerical investigations on interactions between excavations and embankment. Complex nature of the problem is presented. Methodology of numerical simulations and real case examples are described.

2

Metoda i układ do badania właściwości i parametrów generatorów taktów zegarowych

Leśniewicz Marek

Przegląd Elektrotechniczny

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2022

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R. 98, nr 1

59--65

PL

W artykule przedstawiono metodę i układ do badania częstotliwości generatorów. Metoda ma proste podstawy teoretyczne i w praktyce pozwala łatwo i jednoznacznie ocenić dokładność i stabilność oraz zobrazować wander częstotliwości taktu zegarowego. Układ badawczy stanowi kilka najprostszych układów cyfrowych i wzmacniaczy operacyjnych, pozwalających jednak na zaawansowane pomiary napięciowe i obserwacje oscyloskopowe w czasie rzeczywistym. Ich wyniki zostały udokumentowane.

EN

The article presents a method and a system for testing the frequency of generators. The method has simple theoretical foundations and in practice allows you to easily and unequivocally assess the accuracy and stability as well as to visualize the clock frequency wander. The research system consists of several digital circuits and operational amplifiers, however, allowing for advanced voltage measurements and real-time oscilloscope observations. Their results have been documented.

3

Internal model control using artificial neural networks for linear minimum phase systems

Mahmoud Ines, Saidi Imen, Bejaoui Islem

Przegląd Elektrotechniczny

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2022

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R. 98, nr 2

45--48

EN

In this paper, we are interested in the internal model control using neural networks in the case of linear minimum phase systems. We propose, to use the neural internal model control to solve the inversion problem of a model M(z) in order to design the IMC controller. An example application is presented and the implementation of the proposed approach is discussed.

PL

W niniejszym artykule interesuje nas sterowanie modelem wewnętrznym za pomocą sieci neuronowych w przypadku liniowych układów o minimalnej fazie. Proponujemy wykorzystanie neuronowego sterowania modelem wewnętrznym do rozwiązania problemu inwersji modelu M(z) w celu zaprojektowania sterownika IMC. Przedstawiono przykładową aplikację oraz omówiono wdrożenie proponowanego podejścia.

4

Bioleaching of sulfide containing material from the Wiśniówka Quarry: stability and adhesion of secondary products

Pawlowska Agnieszka, Sadowski Zygmunt, Winiarska Katarzyna

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 4

art. no. 149884

EN

Secondary products (minerals) formed during bioleaching play an essential role in this process. Their adhesion to the surface of leached grains can inhibit bioleaching. For this reason, it is crucial to know the physicochemical conditions of adhesion. Selected material from the Wiśniówka Quarry (Kielce, Poland) with increased content of sulfides was subjected to microbial leaching. A precipitate collected from a bacterial culture was used as a secondary product (mainly jarosite). Adhesion and bio-extraction tests were carried out in a column reactor with a mineral bed (particle size 0.8 - 1.2 mm). The cationic surfactant (CTAB), anionic surfactant (SDS), and rhamnolipids (RL) were used to modify the surface of minerals and secondary products. Changes in the surface properties were determined with zeta potential measurements. The cationic surfactant above the 0.5 mM caused stability of jarosite suspension. Also, bioleaching efficiency was the highest for mineral surfaces modified by CTAB. The quantitative interpretation of the adhesion of the secondary product to bioleach mineral material was carried out.

5

Wpływ dodatków mineralnych w cemencie na stabilność napowietrzenia w betonie nawierzchniowym

Dąbrowski Mariusz, Glinicki Michał A., Ignerowicz Arkadiusz, Oleksik Michał, Kucharski Patryk

Magazyn Autostrady

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2022

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Nr 1

29--32

PL

Artykuł przedstawia badania wpływu stosowania cementów z dodatkami mineralnymi CEM II/A-V 42,5 R, CEM II/B-S 42,5 N i CEM III/A 42,5 N na dystrybucję porów w mieszance betonowej przeznaczonej na górną warstwę nawierzchni betonowej zaprojektowanej na agresję środowiska XF4. Przeanalizowano zmiany charakterystyki porów w betonie od wykonania do wbudowania. Próbki pobrano bezpośrednio po wykonaniu mieszanki, po godzinie bezruchu i po wysokoenergetycznym mieszaniu po godzinie bezruchu. Określono charakterystykę porów, właściwości mieszanki betonowej oraz właściwości mechaniczne stwardniałego betonu. Przeanalizowano tendencje zmian całkowitej zawartości powietrza oraz zawartości mikroporów w betonie, wynikające z zastosowania cementu z dodatkami mineralnymi. Uzyskane wyniki świadczą o kompatybilności układu domieszek napowietrzającej i uplastyczniającej z użytymi rodzajami cementu.

EN

The article presents a study on the infl uence of the use of cements with mineral additives CEM II/A-V 42,5 R, CEM II/B-S 42,5 N i CEM III/A 42,5 N on the distribution of pores in a concrete mix intended for the top layer of a concrete pavement designed for the exposure class XF4. The changes in the pore characteristics in concrete from its production to its placement are analysed.

6

Stability and bifurcation analysis for an airfoil model with a high-order nonlinear spring

Li Shuqun, Zhou Liangqiang

Journal of Theoretical and Applied Mechanics

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2022

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Vol. 60 nr 2

185--197

EN

In this paper, the stability and bifurcation of an airfoil model with a high-order nonlinear spring are investigated both analytically and numerically. Two possible types of bifurcation at the equilibrium point are studied. It is proved that the zero characteristic root can only be a single zero. With the help of the center manifold theory and the normal form theory, the expressions of critical bifurcation curves leading to initial bifurcation and secondary bifurcation are obtained. Numerical simulations confirm the theoretical results.

7

Excess load on ships and its effects on stability performance in Nigerian waterways

Adepoju Olusegun Onifade, Bello Kingdom

Journal of Sustainable Development of Transport and Logistics

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2022

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Vol. 7, No. 1

62--72

EN

This research has been carried out to examine the impact of excess shipload on ship performance and stability. The objectives are to analyse the trend of sinking ships in Nigeria occasioned to ship excess load. Secondly, to examine the relationship between load size and ship stability and identify the various factors responsible for ship instability. Data were gathered from operators in the maritime industry using structured questionnaires and interviews as data collection instruments. Four significant stakeholders that can provide information based on their involvement across three strata of management, operation and general cadre were sampled. Pearson Moment Correlation technique has been used to examine the relationship between load size and ship stability, and Analysis of Variance-one was used to identify the various factors responsible for ship instability. The Pearson Moment Correlation technique analysis shows a significant relationship between load size and stability. The analysis of variance revealed that "hogging and sagging" is the most crucial factor among the factors identified for ship instability. It has the highest value of F-ratio of 17.837 with a significance at p<0.05. The research concluded that resultant accidents from the instability of vessels are caused majorly by hogging and sagging of vessels, and notably, the occurrence is much in riverine areas in Nigeria. Loading the vessel has a relationship with the vessel's stability, as depicted from the analysis in this research. Recommendations on how to enhance stability through boat construction, shipbuilding, loading and passenger's use of life jackets, among others were made.

8

Application of Emulsion Liquid Membrane Using Green Surfactant for Removing Phenol from Aqueous Solution: Extraction, Stability and Breakage Studies

Mohammed Ahmed A., Al-Khateeb Rasha Waleed

Journal of Ecological Engineering

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2022

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Vol. 23, nr 1

305--314

EN

Emulsion Liquid Membrane (ELM) has garnered much attention, for its simple operation and high selectivity for the target solute. For an ELM process to be successful, emulsion stability and formulation of liquid membrane are the two main criteria. This study investigated an ELM formulation to identify a suitable green surfactant over the ordinary ones to reduce the utilization of chemicals. The stability of water-in-oil-in-water (w/o/w) was assessed in the following ways, by altering the concentrations of the egg yolk and NaOH, homogenizer speed, and emulsification time. To ascertain the favorable conditions for phenol extraction, several experiments were performed, adopting the batch process, which included many parameters, like the influence exerted by the pH of the external feed, concentration of surfactant, concentration of the internal phase, time of emulsification, homogenization speed and mixing time. Lower breakage and greater extraction efficiency (0.83% and 82.06%, respectively) were attained at 3.5 pH of the external feed, 4% (v/v) of the surfactant, 0.1 M of NaOH, 7 min of emulsification time, 5800 rpm of homogenizer speed and 3 minutes of mixing time. From the results of this study, egg yolk emerged as a good green surfactant. Thus, the ELM process holds promise as an effective technology for stripping phenol from aqueous solutions.

9

Stability of a class of entropies based on fractional calculus

Ferreira Rui A. C.

Journal of Applied Analysis

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2022

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Vol. 28, nr 1

105--107

EN

In this work, we argue about the Lesche stability of some systems that are motivated by the use of fractional derivatives.

10

Assessment of the Stability State and the Risk of Landslides within Berbești Mining Basin (Romania) Post Closure

Faur Florin, Lazar Maria, Apostu Izabela-Maria, Rada Constantin, Moisuc-Hojda Daniel

Inżynieria Mineralna

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2022

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no. 2

59--70

EN

Berbești mining basin, located in the area of the Getic Subcarpathians, is part of the Central Heating Power Plant (CHPP) Govora, in fact representing the mining division, and has four open pits: Alunu, Olteț, Panga, and West Berbești. Given that, at least in Europe, there is the issue of giving up energy production based on the burning of fossil fuels, especially coal, the four open pits will be in operation for a relatively short period of time, and one of the major problems related to the exploitation of lignite deposits is that of the post-closure stability of the lands in the influence area. The research was conducted in such a way as to take into account in the stability analysis the factors and natural causes that predispose the lands in the Getic Subcarpathians to landslides, factors and anthropogenic causes (lignite mining) and the effect of their concomitant action. These stability analyzes took into account different hypotheses related to the geometry of the final slopes and the influence of external factors. Also, a predictive analysis of the long-term stability of the lands (especially the final slopes of the open pits – as they were designed) was carried out, taking into account the behavior over time of the disturbed rocks. Based on the results obtained, after a series of statistical processing, a risk analysis was performed, using a methodology developed by a part of the research team. It should be noted from the outset that the research focused on the West Berbești and Panga mining perimeters, as the lignite mining activity will be completed by the end of 2022 (at most). However, taking into account the similar conditions (geology, morphology, tectonics, seismic zoning, weather and climatic conditions, applied exploitation methods), the research team considers that a significant part of the conclusions and recommendations contained in this study can be considered valid and for the rest of the active perimeters (Alunu and Olteț open pits). In this context, the study ends with a series of conclusions on the stability of land in the Berbești mining basin (West Berbești and Panga perimeters) at the time of cessation of productive activities and recommendations that once put into practice will ensure longterm land stability.

PL

Zagłębie Górnicze Berbești, położone na obszarze Podkarpacia Getyckiego, jest częścią Zagłębia Centralnego (EC) Govora, posiada cztery odkrywki: Alunu, Olteț, Panga i West Berbești. Biorąc pod uwagę, że w Europie istnieje koncepcja rezygnacji z produkcji energii w oparciu o spalanie paliw kopalnych, zwłaszcza węgla, relatywnie krótko funkcjonować będą cztery odkrywki. Jednym z głównych problemów związanych z eksploatacją złóż węgla brunatnego jest stabilność gruntów na obszarze górniczym po zamknięciu eksploatacji. Badania przeprowadzono w taki sposób, aby uwzględnić w analizie stateczności czynniki i przyczyny naturalne, tenedencje terenów Podkarpacia Getyckiego do osuwisk, czynników i przyczyn antropogenicznych (wydobycie węgla brunatnego) oraz skutków oddziaływań towarzyszących. Analizy stateczności uwzględniały różne hipotezy związane z geometrią zboczy i wpływem czynników zewnętrznych. Przeprowadzono także analizę predykcyjną długoterminowej stabilności gruntów (zwłaszcza końcowych zboczy odkrywek) z uwzględnieniem zachowania się gruntów w czasie. Na podstawie uzyskanych wyników, po wykonaniu serii analiz statystycznych przeprowadzono analizę ryzyka, wykorzystując metodologię opracowaną przez część zespołu badawczego. Na wstępie należy zaznaczyć, że badania koncentrowały się na obszarach wydobywczych West Berbești i Panga, ponieważ wydobycie węgla brunatnego zostanie zakończone do końca 2022 roku. Biorąc jednak pod uwagę podobne warunki (geologia, morfologia, tektonika, strefy sejsmiczne, warunki pogodowe i klimatyczne, zastosowanych metod eksploatacji), zespół badawczy uważa, że znaczna część zawartych wniosków i rekomendacji w tym badaniu można uznać za ważne i dla pozostałych obszarów czynnych (odkrywki Alunu i Olteț). W tym kontekście opracowanie kończy się szeregiem wniosków dotyczących stabilności gruntów w zagłębiu górniczym Berbești (zachodnie Berbești i obwód Panga) w momencie zaprzestania działalności produkcyjnej oraz zalecenia, które po wprowadzeniu w życie zapewnią długoterminową stabilność gruntów.

11

Vibration analysis during AZ31 magnesium alloy milling with the use of different toolholder types

Korpysa Jarosław, Zagórski Ireneusz

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 3

489--501

EN

Machining vibrations are an important issue as they occur in all types of machining processes. Due to its negative impact on machining results, this phenomenon is undesirable, and so there have been continuous efforts to find solutions that will minimise it, and thus improve the stability and safety of the machining process. The paper attempts to determine the impact of toolholder type and cutting condition on the vibrations generated while milling an AZ31 magnesium alloy. The tests were performed using the three most common types of toolholders: ER, Shrink Fit and hydraulic. The vibration displacement and acceleration signals were analysed based on parameters such as Peak-to-Peak, Peak, and Root Mean Square. Composite Multiscale Entropy was also applied to check the stability of cutting processes and define the level of signal irregularity. To determine the frequencies of vibrations and to detect chatter vibrations Fast Fourier Transform was performed. This provides information on the stability and enables vibrations to be minimized by avoiding unfavourable cutting conditions.

12

Ranking of Shrubs by Degree of Stability

Semenyutina Alexandra V., Semenyutina Victoria A., Khuzhakhmetova Aliya Sh.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 3

158--166

EN

The relevance is due to the introduction of the subtropical fruit crop Zizyphus jujuba (unabi) to the Volgograd region. For the first time in the conditions of the Volgograd region, the material on the biochemical properties of various varieties of unabi fruits was analyzed and generalized. The ranking of shrubs by change to conditions is based on the fixation of environmental factors and the bioecology of plant individuals based on their physiological and biochemical parameters in field and laboratory conditions. The purpose of the research is to rank the shrubs according to the degree of resistance to stress factors. The objects are plant genotypes of Z. jujuba: large-fruited, medium-fruited and small-fruited. Experimental plantings with their participation are cultivated at the collection site of the Federal Research Center of Agroecology of the Russian Academy of Sciences (Volgograd, Russia).

13

New stability tests for positive descriptor linear systems

Kaczorek Tadeusz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 3

art. no. e140688

EN

The asymptotic stability of positive descriptor continuous-time and discrete-time linear systems is considered. New sufficient conditions for stability of positive descriptor linear systems are established. The efficiency of the new stability conditions are demonstrated on numerical examples of continuous-time and discrete-time linear systems.

14

Problemy z oceną jakości wykonania walcowych powłok stalowych

Hotała Eugeniusz, Kozikowski Damian

Builder

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2022

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R.26, nr 4

32--35

PL

Realne powłoki stalowe mają odchyłki od idealnego kształtu, które powstają przede wszystkim na etapie procesu spawania arkuszy blach. Dotychczasowe obserwacje i pomiary stalowych cylindrycznych powłok rzeczywistych pozwoliły na stworzenie modelu spawalniczej imperfekcji reprezentatywnej. Odchyłki od idealnej geometrii cylindrycznej powłoki w postaci promieniowych lokalnych wgłębień mierzone są w praktyce za pomocą przymiarów geometrycznych, których długość jest określona w wytycznych literaturowych i normowych. W pracy wykazano, że istniejące normowe oraz literaturowe zasady oceny klasy jakości wykonania powłok i wynikające z takich ocen wartości nośności wyboczeniowych mogą w wielu przypadkach dawać znacznie zaniżone wartości w stosunku do realnych nośności, wyznaczonych na podstawie indywidualnych analiz GMNIA.

EN

Fabricated steel shells contain deviations from the ideal shape, which arise primarily during the sheet welding process. Previous observations and measurements of real steel cylindrical shells have made it possible to create a model of representative welding imperfection. Deviations from the ideal geometry of a cylindrical shell in the form of radial local indentations are measured in practice using geometric gauges, the length of which is specified in literature and standard guidelines. It was shown in this paper that the existing standard and literature principles of shells fabrication quality class evaluation and the resulting buckling load values may in many cases give significantly lower values in relation to the real load capacity, determined on the basis of individual GMNIA analyses.

15

A novel approach for power system stabilizer control parameter selection: a case-study on two-area four-machine system

Gude Murali Krishna, Salma Umme

Archives of Electrical Engineering

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2022

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Vol. 71, nr 2

297--407

EN

This paper proposes a power system stabilizer (PSS) with optimal controller parameters for damping low-frequency power oscillations in the power system. A novel meta-heuristic, weighted grey wolf optimizer (GWO) has been proposed, it is a variant of the grey wolf optimizer (GWO). The proposed WGWO algorithm has been executed in the selection of controller parameters of a PSS in a multi-area power system. A two-area four- machine test system has been considered for the performance evaluation of an optimally tuned PSS. A multi-objective function based on system eigenvalues has been minimized for obtained optimal controller parameters. The damping characteristics and eigenvalue location in the proposed approach have been compared with the other state-of-the-art- methods, which illustrates the effectiveness of the proposed approach.

16

Study on stability of self-compacting concrete applied for filling layer structure from paste, mortar and concrete

Liu He, Zhang Jingyi, Yang Yanhai

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

501--522

EN

Self compacting concrete (SCC) filling layer is core structure of China rail track system (CRTS) ? type ballastless track. Construction quality, service performance and durability of CRTS ? ballastless structure are affected by stability of SCC for filling layer. In this study, the stability of SCC of filling layer is researched at three levels as paste, mortar and concrete by theory and experiment. Evaluation indices including bleeding (B), surface bubble rate (θ), thickness of paste (𝜎paste) and thickness of surface mortar (L) are proposed based on the theoretical calculation and analysis. The threshold viscosity of paste 0.394 Pa·s and mixture satisfied area are obtained at paste level based on the relationship between viscosity and B, θ of paste. The mixture satisfied area was defined at mortar level under criterions of maximum value of 𝜎paste and slump flow. Optimal range of gap between neighboring aggregates (λca) 12.4 mm-14.1 mm is chosen by flow ability, passing ability, stable ability of SCC. These research results will help to further understand the stability of SCC.

17

Stabilność biologicznie aktywnych heterocyklicznych pochodnych stilbenu

Kluska Mariusz

Wiadomości Chemiczne

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2021

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[Z] 75, 7-8

997--1016

EN

The work concerns potential applications of stilbene derivatives as preservatives. The structure of stilbene molecule has been known since 1829. One of the most known stilbene derivatives is resveratrol. Many of derivatives synthesized so far show antimicrobial, estrogenic, antitumor and other effects. Stilbene derivatives discussed in this study show activity against 9 different microorganisms, i.e. Staphylococcus aureus 209P FDA, Streptococcus faecalis ATCC 8040, Bacillus subtilis ATCC 1633, Escherichia coli PZHO 26B6, Klebsiella pneumoniae 231, Pseudomonas aeruginosa 5 Rl, Candida albicanus PCM 1409 PZH, Microsporum gypseum K1, Aspergillus fumigates Cl. The following derivatives were tested: chloride of (E)-N-(o-nitrobenzyl)-2- hydroxystilbazole-4, bromide of (E)-N-(p-bromobenzyl)-4’-hydroxystilbazole-4, bromide of (E)-N-(m-bromobenzyl)-4'-hydroxystilbazole-4, chloride of (E)-N-(p- nitrobenzyl)-4'-hydroxystilbazole-4, bromide of (E)-N-(o-bromobenzyl)-2- hydroxystilbazole-4, chloride of (E)-N-(p-chlorobenzyl)-4’-hydroxystilbazole-4. In order to determine of short- and long-term stability of six stilbene derivatives mentioned, tests were carried out using three matrices, i.e. surface water, wastewater and distilled water. Due to possible changes in time, the content of the analyzed derivatives was determined as standard in four time intervals, i.e. after 1 hour, 7 days, 28 days and 12 months. In the research, the isotachophoresis technique was used. The lowest concentrations of the analyzed derivatives were found in wastewater.

18

Application of artificial neural networks in fall prediction

Walczak Tomasz, Sopa Martyna, Pogorzała Adam M.

Vibrations in Physical Systems

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2021

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Vol. 32, nr 2

art. no. 2021210

EN

The problem of fall is still unsolved even though it is a serious problem, especially in group of elderly. Also, another difficulty is to analyse falls that occur in day-to-day life. Those events are hard to observe by specialists and so it is hard to analyse them. Following work contains a description of experimental process for external force-caused fall observation with the use of motion capture system and dynamometric platforms. Data collected according to this protocol were later used for time series neural networks. Obtained results of analysis were compared to popular model of human stability. Conducted inquiry proves that it is possible to detect fall even before it occurs and while it is external force-caused fall the loss of stability develops earlier than it was assumed.

19

Innovative Look at the 'General Method' of Assessing Buckling Resistance of Steel Structures

Czepiżak Dariusz

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr 4

337--345

EN

Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ¯op usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr, from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr, to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.

20

A comprehensive approach to the optimization of design solutions for dry anti-flood reservoir dams

Łydżba Dariusz, Różański Adrian, Sobótka Maciej, Pachnicz Michał, Grosel Szczepan, Rainer Jakub

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr 3

270--284

EN

The article proposes the methodology of designing dams of dry flood control reservoirs. The algorithm is developed so as to meet all the requirements given in the Eurocode 7 and, at the same time, to be efficient in terms of necessary calculation time. Furthermore, the presented numerical procedure enables the optimization of design solutions, e.g. the depth and length of the anti-filtration barrier, by means of parametric analyses. The approach assumes the use of numerical methods, in particular, finite element (FE) analysis. Three-dimensional (3D) reconstruction of the terrain topography and subsoil layer arrangement performed in step (1) sets the base for further analyses. In step (2), the filtration phenomena are assessed based on the 3D analysis of a transient groundwater flow. In step (3), the state of displacement is evaluated and the stability is verified for all the relevant phases of construction and operation of the facility, in particular, in the course of simulated flood detention. The analyses in step (3) are carried out on 2D models corresponding to the design cross-sections of the dam. This significantly reduces the computation time (compared to 3D analysis) and, at the same time, provides a safe estimate of factor of safety. The performance of the proposed algorithm is shown on the numerical examples of the computations concerning the dam of Szalejów Górny dry anti-flood reservoir located in Poland.