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PL
W związku z dostrzeżonymi wadami dotychczas stosowanej metody analizy wpływu drzew na stabilność posadowienia obiektów budowlanych autorzy postanowili zmienić kilka szczegółów procedury. Postanowiono wykorzystać pomysł stosowany już od dawna w innych dziedzinach wiedzy – mapę warstwobarwną. W artykule zamieszczono praktyczne wskazówki, jak taką mapę wykonać i zinterpretować.
EN
Due to the noticed shortcomings of the previously used method of analyzing the impact of trees on the stability of the foundations of building structures, the authors decided to change several details of the procedure. It was decided to use an idea that has long been used in other fields of knowledge – a color layer map. The article contains practical tips on how to create and interpret such a map.
EN
Froth flotation, as one of the most widely used separation approaches in mineral processing, is commonly used to recover valuable components from minerals. However, maintaining high flotation efficiencies is a serious challenge for conventional froth flotation in the face of decreasing particle size of the minerals to be sorted. To date, there have been plenty of reports on the software of nano-bubbles (NBS) in flotation, and the experimental consequences show that nano-bubbles' introduction has given rise to improvement's different grades in the recovery of varieties of minerals, which highlights the great potential of nano-bubbles for mineral flotation. Nanobubbles have smaller bubble radii and unusually high stability compared to conventional flotation bubbles, and their related behavior in flotation has been a hot research topic. This paper reviews some of the methods of preparing nanobubbles, equipment techniques for characterizing nanobubbles, factors affecting their stability, and some of the popular doctrines. In particular, the reinforcing mechanism of nanobubbles in the particle flotation process is discussed, first, the nanobubbles improve the electrostatic attractiveness with the particles by achieving the charge inversion while the nanobubbles that was adsorbed on the particles' surface will cover a share of the charge, which decreases the electrostatic repulsive force between the particles; and second, the nanobubbles can act as a bridge between the surfaces of the two particles, which advances the agglomeration between the particles. This review aims to be able to further advance the research related to the industrialization of nanobubbles.
EN
The constant increase in energy demand and the need to reduce the carbon footprint on the environment has put countries in a race against time, looking for alternative resources or ways to supply this need. One of the main resources is solar radiation, which can be used to generate energy, initially on a small scale, but in recent years has been directed towards supplying large cities. The economic, political, and social investment must respond to planning and expansion criteria in order to generate feasible proposals. Through simulation of a real electrical system, the voltage instability was determined, which was corrected at software level by entering a photovoltaic solar plant, being this dimensioned from the PV curve obtained. Finally, the optimal location for the development of a solar photovoltaic plant among four possible scenarios was obtained through the application of an optimization algorithm. This approach was converted into an alternative applicable to different geographical locations.
EN
In the work improved system of equation of plane-parallel movement of the road train with single-axle O1-category trailer. Defined lateral reactions on the vehicle and trailer wheels at body roll, wheels slip caused by body roll and also developed road train spatial mathematical model in a transverse plane. This model is used to study the road train course stability with O1-category trailer. It is shown that the spatial model of road train with no vehicle and trailer wheels inclination has the same divergent instability characteristic as the plane road train layout.
PL
W artykule omówiono zagadnienie wpływu OZE, którego udział w sieci elektroenergetycznej wzrasta i będzie dalej ulegał znacznemu wzrostowi w niedalekiej przyszłości. Będzie to powodowało nowe, niespotykane wcześniej w systemie elektroenergetycznym, problemy związane z szeroko rozumianą stabilnością systemu elektroenergetycznego. Zwrócono też uwagę na fakt, że rozwój energetyki rozproszonej wpływa na nowe zadania i uwarunkowania pracy układów EAZ, a operatorzy sieci przewidują decentralizację i automatyzację systemów regulacji napięcia i sankcjonowanie pracy wyspowej. Przydatnym narzędziem do analizy stanu stabilności w systemach może być pomiar PMU (Phasor Measurment Unit), coraz częściej dostępny w przekaźnikach zabezpieczeniowych jako dodatkowa funkcja. Zastosowanie synchrofazorów i techniki PMU w systemie elektroenergetycznym obejmuje już nie tylko szeroko omawianą ocenę stabilności, ale także może być przydatne w tworzeniu obszarowych - Wide Area - systemów zabezpieczeń WAP oraz systemów sterowania WACS. Oferenci, przygotowując się do zmian w systemie elektroenergetycznym, opracowują automatyki wspomagające utrzymanie stabilności w systemie. Przykładem może być firma GE, która wprowadziła na rynek produkt PowerNode, do którego nawiązano w niniejszym artykule.
EN
The article discusses the issue of the impact of Renewable Energy Sources on HV network, the share of which in the power grid is increasing and will continue to increase significantly in the near future. This will cause new problems, not previously encountered in the power system, related to the widely understood stability of the electricity system. Attention was also drawn to the fact that the development of distributed energy affects new tasks and conditions for the operation of Power Protection Automation systems, and network operators envisage decentralization and automation of voltage regulation systems and accepting of island operation of the Power System. A useful tool for analyzing the state of stability in systems may be PMU (Phasor Measurement Unit) measurement, which is more often available in protection relays as an additional function. The use of synchrophasors and PMU technology in the power system not only covers the widely discussed Power System stability assessment, but can also be useful in creating Wide Area WAP security systems and WACS control systems. In preparation for changes in the Power System, bidders are developing automation systems that help maintain stability in the system. An example is GE, which introduced the product PowerNode, which is referred to in this publication.
7
Content available remote Power system small signal stability enhancement using fuzzy based STATCOM
EN
This paper describes how fuzzy based STATCOM was used to improve the small signal stability of Tis Abay II electric power generation. Tis Abay II is a power generation facility in Ethiopia, located in the Bahir Dar Amhara region, with a nominal apparent power generating capacity of 40MVA. The oscillating nature of a rotating machine, the imbalance of load and generation, the presence of exciter and compensator, and the occurrence of faults all contribute to the disruption on an interconnected power network. The frequency oscillation of the existing plant was evaluated in the absence of a power system stabilizer (PSS) and an adaptive fuzzy logic controller (AFLC). The proposed system network configuration was used to fine-tune the mathematical analysis of synchronous machine data and model. The proposed model incorporates SMIB system modeling and an AFLC. MATLAB Simulink was used to simulate the effect of the PSS and AFLC on rotor speed, angle, and electrical torque. The proposed system's power system dynamic stability was improved using a PSS and a fuzzy logic-based STATCOM. According to the simulation results, FLCbased STATCOM is best suited for improving the dynamic stability of Tis Abay II power generation.
PL
W tym artykule opisano, w jaki sposób STATCOM oparty na rozmyciu został wykorzystany do poprawy stabilności małych sygnałów w wytwarzaniu energii elektrycznej Tis Abay II. Tis Abay II to zakład energetyczny w Etiopii, położony w regionie Bahir Dar Amhara, o nominalnej mocy pozornej wytwarzania 40MVA. Oscylacyjny charakter maszyny wirującej, niezrównoważenie obciążenia i generacji, obecność wzbudnicy i kompensatora oraz występowanie usterek przyczyniają się do zakłóceń w połączonej sieci energetycznej. Oscylacje częstotliwości istniejącej elektrowni zostały ocenione przy braku stabilizatora systemu elektroenergetycznego (PSS) i adaptacyjnego sterownika logiki rozmytej (AFLC). Zaproponowana konfiguracja sieci systemu została wykorzystana do dostrojenia analizy matematycznej danych i modelu maszyny synchronicznej. Proponowany model obejmuje modelowanie systemu SMIB i AFLC. MATLAB Simulink wykorzystano do symulacji wpływu PSS i AFLC na prędkość wirnika, kąt i moment elektryczny. Stabilność dynamiczna systemu elektroenergetycznego proponowanego systemu została poprawiona za pomocą PSS i STATCOM opartego na logice rozmytej. Zgodnie z wynikami symulacji, STATCOM oparty na FLC najlepiej nadaje się do poprawy dynamicznej stabilności generacji Tis Abay II.
PL
W pracy za pomocą zmian przewodności zbadano zmiany konformacyjne proteiny BSA oraz jej kompleksów (BSA-Au oraz BSA-NAA) pod wpływem promieniowania UV oraz MF aplikowanego frakcyjnie w dawkach (3 × 10 min oraz 6 × 10 min) oraz w sposób ciągły (30 min, 60 min). Wykonano analizę porównawczą wpływu promieniowania UV i mikrofalowego w dawkach ciągłych i frakcyjnych na BSA, BSA-Au, BSA-NAA oraz przeanalizowano czułość na pole elektromagnetyczne z zakresu UV i MF dla badanych substancji. Udowodniono efekt przyspieszonych zmian konformacyjnych pod wpływem pola elektromagnetycznego z zakresu UV i MF. Wykazano wpływ czynników na stabilność BSA i jej kompleksów zależny od: rodzaju czynnika, sposobu jego aplikacji oraz czasu ekspozycji. Najbardziej czuły na pole elektromagnetyczne okazał się kompleks BSA-Au.
EN
In this study, the conformational changes of BSA protein and its complexes (BSA-Au and BSA-NAA) under UV and MF radiation applied in fractional doses (3 × 10 min and 6 × 10 min) and continuously (30 min, 60 min) were investigated by means of conductivity changes. A comparative analysis of the effect of UV and microwave radiation in continuous and fractional doses on BSA, BSA-Au, BSA-NAA was performed, and the sensitivity to UV and MF electromagnetic fields of the tested substances was analysed. The effect of accelerated conformational changes under the influence of UV and MF electromagnetic field was proved. The influence of the factors on the stability of BSA and its complexes was shown to depend on: the type of agent, the method of its application and the exposure time. The most sensitive to the electromagnetic field turned out to be the complex BSA-Au.
EN
This paper aims to determine the effect of global economic policy uncertainty on the banking system's stability in Asian countries. The dependent variable in the study is measured through the bank's payment risk Zscore. The primary explanatory factor is global economic policy uncertainty, and other control variables include the banking system's characteristics and the national economic environment. Asian banking systems’ data are collected from World Bank between 2008 and 2020. Based on the System Generalized Method of Moments, the main results indicate that global economic policy uncertainty is seriously exacerbating the instability of the banking system of Asian countries. The study also shows that the ability to use mobilized capital and the degree of concentration of the system reduces the adverse impact of global economic policy uncertainty on the stability of the banking system in Asian countries.
PL
Celem niniejszego artykułu jest określenie wpływu niepewności globalnej polityki gospodarczej na stabilność systemu bankowego w krajach azjatyckich. Zmienna zależna w badaniu jest mierzona za pomocą wskaźnika Zscore ryzyka płatniczego banku. Głównym czynnikiem objaśniającym jest niepewność globalnej polityki gospodarczej, a inne zmienne kontrolne obejmują charakterystykę systemu bankowego i krajowe środowisko gospodarcze. Dane dotyczące azjatyckich systemów bankowych pochodzą z Banku Światowego w latach 2008-2020. W oparciu o system uogólnionej metody momentów, główne wyniki wskazują, że niepewność globalnej polityki gospodarczej poważnie pogarsza niestabilność systemu bankowego krajów azjatyckich. Badanie pokazuje również, że zdolność do wykorzystania zmobilizowanego kapitału i stopień koncentracji systemu zmniejsza niekorzystny wpływ niepewności globalnej polityki gospodarczej na stabilność systemu bankowego w krajach azjatyckich.
EN
We study the behavior of a collapsible tube conveying a fluid subject to external pressure that could occur in many physiological applications. The method of rotating spines is developed to enable an automatic mesh adaptation when the tube is deformed largely. We examine bifurcation diagrams when the tube is collapsed under a pressure driven condition and reveal that multiple solutions exist for a range of the Reynolds number. The stability characteristic of the system is discovered by determining stability of these solutions by the eigenvalue method for the first time, which is validated by solving a time-dependent problem of the system.
EN
The current paper focuses on assessing key parameters affecting the extraction of Chlorpyrifos as well as emulsion stability using the emulsion liquid membrane technology. Five parameters affecting the extraction have been studied: homogenizer speed, emulsification time, agitating time, surfactant concentration, and stripping phase concentration taking into consideration the emulsion breaking. Experiments proved that using the resulting optimum values will maximize both extraction and stripping efficiencies (93.8% and 94.7% respectively), while minimizing the emulsion breakage (increasing the stability of emulsion) to 0.73% with no need to employ a carrier agent. A 10 min agitating time, 3% (v/v) Span 80 as a surfactant, 12700-rpm homogenizer speed, 0.25 M HCl as an internal phase concentration, and 5 min emulsification time are chosen to be the optimum parameters’ values. A study of extraction kinetics and estimation of mass transfer coefficient was also accomplished (3.89×10-9m/s). The conclusions of this work can be extended to the removal of other types of pesticides from water.
EN
This paper presents a novel approach to analyzing the robust stability of interconnected embedded systems. The paper starts by discussing the challenges associated with designing stable and robust embedded systems, particularly in the context of interconnected systems. The proposed approach combines the H∞ control theory with a new model for interconnected embedded systems, which takes into account the effects of communication delays and data losses. The paper provides a detailed mathematical analysis of the new model and presents several theorems and proofs related to its stability. The effectiveness of the proposed approach is demonstrated through several practical examples, including a networked control system and a distributed sensor network. The paper also discusses the limitations of the proposed approach and suggests several directions for future research. The proposed filter design method establishes a sufficient condition for the asymptotic stability of the error system and the satisfaction of a predefined H∞ performance index for time-invariant bounded uncertain parameters. This is achieved through the use of the strict linear matrix inequalities (LMI) approach and projection lemma. The design is formulated in terms of linear matrix inequalities (LMI). Numerical examples are provided to demonstrate the effectiveness of the proposed filter design methods.
EN
This paper examines a third-order fractional partial differential equation (FPDE) in the Caputo sense. The Theta difference method (TDM) is utilized to investigate the problem, and a first-order difference scheme is developed. Stability estimates are obtained by applying the Von Neumann analysis method. A test problem is presented as an application, and numerical results are obtained using Matlab software. Error estimates, as well as exact and approximate solutions are presented in a data analysis table. The simulation results are shown through error analysis tables and figures.
EN
Kryvyi Rih iron ore basin consists of complex structured ore deposits and is developed by the underground method at depths of over 1000 m. The underground method is used to mine reserves of rich iron ores with a useful component content of more than 59% applying bulk ore and rock caving systems. This leads to significant changes in the stress state of the rock massif. During underground operations, mine workings are strained and in some cases destructed. As a result, enterprises are constantly increasing operating costs for maintaining mine workings, which adversely impacts the cost of production. Industrial research results demonstrate that in most cases workings fail in their upper part which is vaulted in shape. Available methods for determining the state of rocks around mine workings do not fully take into account physical and mechanical properties of the rocks in which the working is located. The developed technique allows determining not only the destructive pressure impacting the workings, but also the angle at which the destructive force acts. This technique differs from the available ones in taking into account not only mining and geological characteristics of the deposit, but also most factors of physical and mechanical properties of rocks. This technique helps to choose a rational place for driving mine workings at the stage of design, thus avoiding significant additional cost for their maintenance.
PL
W kopalni Krzywy Róg występują złoża rudy o złożonej strukturze, wydobywane metodą podziemną z głębokości ponad 1000 m. Stosując systemy zawałowe eksploatuje się złoża bogatych rud żelaza o zawartości składników użytecznych powyżej 59%. Prowadzi to do znacznych zmian stanu naprężeń masywu skalnego. Podczas prac podziemnych wyrobiska kopalniane podlegają naprężęniom, a w niektórych przypadkach ulegają zniszczeniu. W efekcie przedsiębiorstwa stale podwyższają koszty eksploatacji wyrobisk górniczych, co niekorzystnie wpływa na koszty produkcji. Wyniki badań przemysłowych wskazują, że w większości przypadków wyrobiska zawodzą w swojej górnej części. Dostępne metody określania stanu skał wokół wyrobisk górniczych nie uwzględniają w pełni właściwości fizycznych i mechanicznych skał, w których znajduje się wyrobisko. Opracowana technika pozwala na określenie nie tylko ciśnienia destrukcyjnego działającego na wyrobiska, ale również kąta działania siły destrukcyjnej. Technika ta rożni się od dostępnych tym, że uwzględnia nie tylko cechy górniczo-geologiczne złoża, ale także większość czynników właściwości fizykomechanicznych skał. Technika ta pozwala już na etapie projektowania na dobór racjonalnych miejsc prowadzenia wyrobisk górniczych, unikając w ten sposób znacznych dodatkowych kosztów ich utrzymania.
EN
The paper presents the study and a functional analysis of requirements of the world metallurgical industry to the quality of underground iron ores at underground mines of Ukraine. There are found dependencies of the impact of the shape and parameters of compensation spaces on their stability and broken ore quality indicators. It is proved that a vertical trapezoidal compensation room possesses the highest stability and is stable within the range of all the considered depths, even in ores with hardness of 3–5 points. Less atabiity is demonstrated by a vertical compensation room of a vaulted shape with minor falls in the abutment of the room vault in ores with hardness of 3–5 points at the depth of 2000 m, and a tent-shaped one where falls of varying intensity occur in the lower part of inclined exposures of the tent in ores with hardness of 3–5 points at the depth of 1750 m or more. The horizontal compensation room is of the lowest stability; falls occur in ores with hardness of 3–5 points at the depth of 1400 m, and at the depths of 1750–2000 m it remains stable only in harder ores. It is established that the use of compensation rooms of high stability makes it possible to achieve their maximum volume, increase the amount of pure ore extracted, reduce its dilution, enhance the quality of the mined ore mass and concequently increase its price and competitiveness of marketable products.
PL
Artykuł przedstawia studium i analizę funkcjonalną wymagań światowego przemysłu metalurgicznego co do jakości rud żelaza w podziemnych kopalniach Ukrainy. Stwierdzono zależności wpływu kształtu i parametrów przestrzeni kompensacyjnych na ich stateczność i wskaźniki jakości rudy. Udowodniono, że komora wyrównawcza w kształcie trapezu pionowego charakteryzuje się największą stabilnością i jest stabilna w zakresie wszystkich rozważanych głębokości, nawet w rudach o twardości 3–5 punktów. Mniejszą stateczność wykazuje komora kompensacji pionowej o kształcie sklepionym z niewielkimi spadkami w przyczółku sklepienia komory w rudach o twardości 3–5 punktów na głębokości 2000 m. Komora z opadami o rożnym natężeniu występuje w dolnej części nachylonych odsłonięć namiotu w rudach o twardości 3–5 punktów na głębokości 1750 m lub większej. Pomieszczenie kompensacji poziomej ma najmniejszą stateczność; spadki występują w rudach o twardości 3–5 punktów na głębokości 1400 m, a na głębokościach 1750–2000 m pozostają stabilne tylko w rudach twardszych. Stwierdzono, że zastosowanie komór kompensacyjnych o dużej stabilności umożliwia osiągnięcie ich maksymalnej objętości, zwiększenie ilości wydobywanej czystej rudy, zmniejszenie jej rozrzedzenia, poprawę jakości wydobywanej masy rudy, a co za tym idzie, wzrost jej ceny i konkurencyjności rynkowej.
PL
W artykule omówiono różne sposoby wyznaczania długości wyboczeniowej słupów stalowych ram portalowych. Rozważania ograniczono do wyboczenia ramy w płaszczyźnie, w której jest ona układem przechyłowym. Przedstawiono i porównano ze sobą łącznie trzy sposoby określania długości wyboczeniowej. Na koniec przeprowadzono uproszczoną ocenę wpływu wielkości długości wyboczeniowej na poziom wytężenia słupa ramy portalowej.
EN
The article discusses various ways of determining the column buckling length of steel portal frames. Considerations were limited to in-plane buckling of the frame in which the frame is characterized as a sway. A total of three methods of determining the buckling length are presented and compared. Finally, a simplified evaluation of the effect of buckling length on the utilization ratio of the column was carried out.
EN
This paper investigates the possibility of automatically linearizing nonlinear models. Constructing a linearised model for a nonlinear system is quite labor-intensive and practically unrealistic when the dimension is greater than 3. Therefore, it is important to automate the process of linearisation of the original nonlinear model. Based on the application of computer algebra, a constructive algorithm for the linearisation of a system of non-linear ordinary differential equations was developed. A software was developed on MatLab. The effectiveness of the proposed algorithm has been demonstrated on applied problems: an unmanned aerial vehicle dynamics model and a twolink robot model. The obtained linearized models were then used to test the stability of the original models. In order to account for possible inaccuracies in the measurements of the technical parameters of the model, an interval linearized model is adopted. For such a model, the procedure for constructing the corresponding interval characteristic polynomial and the corresponding Hurwitz matrix is automated. On the basis of the analysis of the properties of the main minors of the Hurwitz matrix, the stability of the studied system was analyzed.
EN
Mercury and its compounds are among the most dangerous and toxic substances in the environment. As part of the study, several exploratory analyses and statistical tests were conducted to demonstrate how low and stable mercury content is in municipal waste. A statistical analysis of the mercury content in waste (waste codes 19 12 12 and 20 03 01) was carried out using advanced IT tools. Based on 32 results for each waste, the maximum mercury concentration was 0.062 mg/kg dry weight (EWC code 19 12 12) and 0.052 mg/kg dry weight (EWC code 20 03 01). The analysis, data inference, and modeling were performed according to the CRISP-dm methodology. The results obtained were compared with the maximum allowable mercury concentrations for agricultural soils (2 mg/kg dry weight) and the provisions of the Minamata Convention (1 mg/kg). The average, median, and maximum observed mercury concentrations in waste are significantly lower than the assumed levels of 2 mg/kg (permissible concentrations for II-1 soils) and 1 mg/kg (Minamata Convention). The stability of mercury content in waste was examined. Descriptive statistics, statistical tests, and regression modeling were used. The tests and analyses performed showed an insignificant variation in the mercury content of the wastes with codes 19 12 12 and 20 03 01. No trend or seasonality was observed. The analyses and tests performed confirmed that the data are stable, and the values are low.
EN
Recently, air pollution has received much attention as a result of reflections on environmental issues. Accordingly, the hub location problem (HLP) seeks to find the optimal location of hub facilities and allocate points for them to meet the demands between source-destination pairs. Thus, in this study, decisions related to location and allocation in a hub network are reviewed and a multi-objective model is proposed for locating and allocating capacity-building facilities at different time periods over a planning horizon. The objective functions of the model presented in this study are to minimize costs, reduce air pollution by diminishing fuel consumption, and maximize job opportunities. In order to solve the given model, the General Algebraic Modeling System (GAMS) along with innovative algorithms are utilized. The results presented a multi-objective sustainable model for full-covering HLP, and provided access to a hub network with minimum transport costs, fuel consumption, and GHG (greenhouse gas) emissions, and maximum job opportunities in each planning horizon utilizing MOICA (multi-objective imperialist competitive algorithm) and GAMS to solve the proposed model. The study also assessed the performance of the proposed algorithms with the aid of the QM, MID, SM, and NSP indicators, acquired from comparing the proposed meta-heuristic algorithm based on some indicators, proving the benefit and efficiency of MOICA in all cases.
EN
The guide of the Hyperloop system in the paper is mathematically represented as a continuous system along which the force from the capsule travels, with the capsule in turn represented as a discrete system. The simulations discussed in the article were used to determine the displacements of the magnet elements. ANSYS software was used to perform the simulations using finite element calculations (FEM). The stability of the capsule will be determined from the results of the displacements present in the system. Taking into account the existing conditions in the magnet and guide assembly system, the simulation results were used to analyse stability in technical and stochastic terms (Lyapunov criteria) for non-linear systems. In the technical stochastic stability analysis, the transverse displacements of the electromagnets were used. The probability of unstable Hyperloop motion was then calculated.
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