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Search results for: rubber bearings
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Methods of deep modification of low-bearing soil for the foundation of new and spare air runways
PublicationAfter analyzing the impact of aircraft on the airport pavement (parking spaces, runways, startways), it was considered advisable to consider the problem of deep improvement or strengthening of its subsoil. This is especially true for low-bearing soil. The paper presents a quick and effective method of strengthening the subsoil intended for the construction of engineering structures used for civil...
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Experimental comparison of the transition speed of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
PublicationA journal bearing test bench is used to find the transition speed between the hydrodynamic and mixed lubrication regimes for a modified magnetorheological (MR) fluid. It is shown that the transition speed of the bearing can be reduced by applying a local magnetic field near minimum film when it is lubricated with the MR fluid, and that this will only marginally increase friction. The lubricating performance of the MR fluid is compared...
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The New Elastomeric Compounds Made of Butyl Rubber Filled with Phyllosilicates, Characterized by Increased Barrier Properties and Hydrophobicity and Reduced Chemical Degradation
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Inspection of rubber linings operating in flue gas desulphurisation units. Inspekcje wykładzin gumowych w warunkach instalacji odsiarczania spalin.
PublicationPomiary metodą EIS wykładzin gumowych przeprowadzono w warunkach polowych.Stwierdzono, że najlepszym miernikiem jakości powłoki jest pojemność elektryczna powłoki. Sposób wyznaczania zwartości wilgoci w powłoce oparty został na równaniu Brashera-Kingsbury´ego. Wyniki porównano z oznaczeniami wilgoci w wykładzinie metodami niszczącymi przeprowadzonymi w tych samych miejscach co badania elektrochemiczne.
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Użyteczność niektórych enzymów bakterii Thermus ruber w przetwórstwie sacharydów żywności
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Non-standard binary weighted number systems
PublicationZdefiniowano szeroką klasę binarnych systemów wagowych. Wszystkie sa wzajemnie jednoznaczne ale mogą być zupełne lub niezupełne. Jeżeli wagi systemu są kolejnymi liczbami naturalnymi to system jest minimalny.Jesli wagi sa kolejnymi potęgami podstawy Z to system jest maksymalny. W przestrzeni między tymi systemami znajdują się inne systemy binarne. Kilka z nich przedstawiono w referacie.
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Lower bound on the paired domination number of a tree
PublicationW pracy przedstawione jest ograniczenie dolne dla liczby dominowania parami oraz scharakteryzowane są wszystkie drzewa ekstremalne.
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Empirical Probability Distributions with Unknown Number of Components
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Bounds on the vertex-edge domination number of a tree
PublicationA vertex-edge dominating set of a graph $G$ is a set $D$ of vertices of $G$ such that every edge of $G$ is incident with a vertex of $D$ or a vertex adjacent to a vertex of $D$. The vertex-edge domination number of a graph $G$, denoted by $\gamma_{ve}(T)$, is the minimum cardinality of a vertex-edge dominating set of $G$. We prove that for every tree $T$ of order $n \ge 3$ with $l$ leaves and $s$ support vertices we have $(n-l-s+3)/4...
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Influence of edge subdivision on the convex domination number
PublicationWe study the influence of edge subdivision on the convex domination number. We show that in general an edge subdivision can arbitrarily increase and arbitrarily decrease the convex domination number. We also find some bounds for unicyclic graphs and we investigate graphs G for which the convex domination number changes after subdivision of any edge in G.
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Entanglement and Nonlocality are Inequivalent for Any Number of Parties
PublicationUnderstanding the relation between nonlocality and entanglement is one of the fundamental problems in quantum physics. In the bipartite case, it is known that these two phenomena are inequivalent, as there exist entangled states of two parties that do not violate any Bell inequality. However, except for a single example of an entangled three-qubit state that has a local model, almost nothing is known about such a relation in multipartite...
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On the super domination number of lexicographic product graphs
PublicationThe neighbourhood of a vertexvof a graphGis the setN(v) of all verticesadjacent tovinG. ForD⊆V(G) we defineD=V(G)\D. A setD⊆V(G) is called a super dominating set if for every vertexu∈D, there existsv∈Dsuch thatN(v)∩D={u}. The super domination number ofGis theminimum cardinality among all super dominating sets inG. In this article weobtain closed formulas and tight bounds for the super dominating number oflexicographic product...
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T-colorings, divisibility and circular chromatic number
PublicationLet T be a T-set, i.e., a finite set of nonnegative integers satisfying 0 ∈ T, and G be a graph. In the paper we study relations between the T-edge spans espT (G) and espd⊙T (G), where d is a positive integer and d ⊙ T = {0 ≤ t ≤ d (max T + 1): d |t ⇒ t/d ∈ T} . We show that espd⊙T (G) = d espT (G) − r, where r, 0 ≤ r ≤ d − 1, is an integer that depends on T and G. Next we focus on the case T = {0} and show that espd⊙{0} (G) =...
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Weakly convex domination subdivision number of a graph
PublicationA set X is weakly convex in G if for any two vertices a; b \in X there exists an ab–geodesic such that all of its vertices belong to X. A set X \subset V is a weakly convex dominating set if X is weakly convex and dominating. The weakly convex domination number \gamma_wcon(G) of a graph G equals the minimum cardinality of a weakly convex dominating set in G. The weakly convex domination subdivision number sd_wcon (G) is the minimum...
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Graphs with convex domination number close to their order
PublicationW pracy opisane są grafy z liczbą dominowania wypukłego bliską ilości ich wierzchołków.
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Application of Intelligent Conversational Agents in E-learing Environments
PublicationThe paper concerns intelligent tutoring systems and concentrates on apliaction of virtual mentors in distance learning environments. Different educational agent types are described. The prototype of an agent developed at Gdansk University of Technology is also presented, as well as its internal representation and construction. Benefits of virtual mentors applied in distance learning are also pointed out.
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Multimedia services applied to noise and hearing monitoring and measuring
PublicationThe goal of this chapter is to show a research study related to processing of data acquired by the multimedia services engineered at the multimedia systems department (MSD) of the Gdansk University of Technology. This concerns a survey on noise threat employing the multimedia noise monitoring system (MNMS) and hearing tests performed by the "I can hear. . . " system. The obtained results of the noise measurements revealed that...
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Investigation of Noise Threats and Their Impact on Hearing in Selected Schools
PublicationNoise measurements conducted in selected schools in Gdansk area are presented in this paper. The main aim of this research was to determine noise threats at schools. Some objective measurements of the acoustic climate were performed employing a noise monitoring station engineered at the Multimedia System Department, Gdansk University of Technology. Simultaneously, subjective noise annoyance examinations were carried out among pupils...
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Audiovisual speech recognition for training hearing impaired patients
PublicationPraca przedstawia system rozpoznawania izolowanych głosek mowy wykorzystujący dane wizualne i akustyczne. Modele Active Shape Models zostały wykorzystane do wyznaczania parametrów wizualnych na podstawie analizy kształtu i ruchu ust w nagraniach wideo. Parametry akustyczne bazują na współczynnikach melcepstralnych. Sieć neuronowa została użyta do rozpoznawania wymawianych głosek na podstawie wektora cech zawierającego oba typy...
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Computer simulations of hearing aid acoustical system performance
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Fitting the mobile device characteristics to the user's hearing preferences
PublicationA method for fitting the mobile computer audio characteristics to the user's hearing preferences is proposed. The process consists of two stages: calibration and dynamics processing. During the calibration phase the user performs a loudness scaling test giving their response regarding the perceived loudness. The dynamics processing made on above basis sets the loudness to the most comfortable level. The processing accounts both...
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A study on signal processing methods applied to hearing aids
PublicationThis paper presents a short survey on current technology available in hearing aids with a focus on digital signal processing techniques used. First, factors influencing the hearing aid effectiveness are introduced. Then, examples of the present DSP methods and strategies are provided. Also, a description of current limitations of hearing aids and future trends of development are shown. Finally, the notion of computational auditory...
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Virtual hearing aid - the computer application for education purposes.
PublicationZrealizowano aplikację komputerową demonstrującą zasady działania aparatów słuchowych. Osoba z dobrym słuchem ma możliwość zapoznania się z problemem niedosłuchu i działaniem aparatu. Aplikacja wyposażona jest w intuicyjny interfejs, który przedstawia elementy aparatu słuchowego na schemacie blokowym z opcjami dotyczącymi źródła dźwięku, typu szumu oraz ustawień aparatu. Aplikacja wzbogacona jest o materiały dydaktyczne, opisujące...
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Application of hybrid signals processors to speech and hearing aids
PublicationDzięki postępowi w technice Cyfrowych Procesorów Sygnałowych (ang. DSP) stało się możliwe budowanie miniaturowych protez słuchu i mowy. Mimo niewielkich wymiarów procesory te są w stanie wykonywać złożone algorytmy. Ich dodatkową zaletą jest łatwość zmiany oprogramowania, a co za tym idzie łatwość zmiany dziedziny zastosowań. W pracy skupiono się na zagadnieniach związanych z projektowanie i implementacją algorytmów mających zastosowanie...
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Theoretical analysis and experimental tests of tilting pad journal bearings with shoes made of polymer material and low-boiling liquid lubrication
PublicationSelecting the appropriate bearing system for the rotor requires a good knowledge of the available solutions and the operating conditions of the machine. For newly designed machinery operating in adverse conditions, selecting bearings that ensure correct and long-lasting operation can be extremely challenging. Difficulties in- crease when the machine’s operating parameters are beyond the technical capabilities of available technical solutions....
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Model and laboratory simulation of a induction motor for diagnostic purposes
PublicationStatistics say that bearings are this part of induction motors which is most susceptible to damage. The equipment employed for bearing diagnostics usually makes use of vibrations as the criterion for technical condition of the bearings. A faulty bearing results in additional motor vibrations. They are reflected in the harmonic content of stator currents. In certain operating conditions the current signal is the sole source of information...
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EXPERIMENTAL STUDY OF DIFFERENT SUPPLY DESIGNS IN HYDRODYNAMIC THRUST BEARINGS = Badania doświadczalne różnych sposobów smarowania wzdłużnych łożysk ślizgowych
PublicationHydrodynamiczne łożyska wzdłużne charakteryzują się znacznymi stratami tarcia, które przyczyniają się do wzrostu temperatury łożyska i obniżenia jego nośności. Obecnie olej smarujący jest zazwyczaj chłodzony w zewnętrznych układach chłodzenia. Po schłodzeniu olej jest dostarczany z powrotem do korpusu łożyska, z reguły do przestrzeni między klockami łożyska. Skuteczność dostarczania schłodzonego oleju w pobliże wlotu do szczeliny...
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Experimental research on water lubricated marine stern tube bearings in conditions of improper lubrication and cooling causing rapid bush wear
PublicationWater lubricated bearings are popular in sliding bearings of marine propeller shafts, turbines and pump shafts. Such popularity is partly due to their simple construction which also means a relatively affordable price. In practical experience one may also observe cases of rapid wear or even malfunctions of this bearings, some of which may be caused by insufficient flow of lubricant leading to overheating. The conducted...
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First tests of water lubricated propeller shaft bearings = Wstępne badania zespołu smarowanych wodą łożysk okrętowego wału śrubowego
PublicationW pierwszej części referatu zaprezentowano nowe stanowsko badawcze przy pomocy którego można badać smarowane wodą łożyska wału śrubowego. W drugiej części pracy przedstawiono uzyskane wyniki pomiarów oporów ruchu i trajektorii osi wału.
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THE INFLUENCE OF HOUSING ARRANGEMENT AND INTERFERENCE ON PRELOAD AND THEORETICAL LIFETIME OF A SYSTEM OF TAPER ROLLER BEARINGS OF A HIGH SPEED SHAFT OF A WIND TURBINE GEARBOX
PublicationA system of two taper roller bearings can carry loads with a high ratio of axial load to radial load. Such a system was proposed for a wind turbine gearbox following the poor durability of original bearing design with the aim of increasing durability. Because of size limits, a proposed system is composed of two different taper roller bearings. Standard manufacturers’ catalogues do not provide information on recommended preload...
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The influence of feed rate and shear forces on the devulcanization process of ground tire rubber (GTR) conducted in a co-rotating twin screw extruder
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The influence of feed rate and shear forces on the devulcanization process of ground tire rubber (GTR) conducted in a co-rotating twin screw extruder
PublicationThe search for new ways to recycling of rubber waste has been the aim of many studies conducted by research centers and companiesworldwide. The results of our investigations on the process of continuous thermomechanical devulcanization of ground tire rubber using a twin screw extruder are presented.We used a co-rotating twin screw extruder with a special configuration of plasticizing unit, enabling generation of considerable shear...
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Interrelationship between total volatile organic compounds emissions, structure and properties of natural rubber/polycaprolactone bio-blends cross-linked with peroxides
PublicationNatural rubber/polycaprolactone (NR/PCL) bio-based blends with different organic peroxides were prepared using an internal batch mixer and subsequently cross-linked at 170°C. Two types of commonly used organic peroxides, dicumyl peroxide and di(tert-butylperoxyisopropyl)benzene peroxide, were applied as free-radical initiator. Cross-linking efficiency of NR/PCL blends were investigated using oscillating disc rheometer measurements,...
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Super tough interpenetrating polymeric network of styrene butadiene rubber‐poly (methyl methacrylate) incorporated with general purpose carbon black ( N660 )
PublicationA classic set of polymeric interpenetrating polymeric network (IPN) microcomposites has been fabricated using an elastomer—styrene butadiene rubber [SBR], a thermoplastic poly(methyl methacrylate)-PMMA and with carbon black (CB)-N660 as a filler and reinforcing agent. This synthesized IPN composite can be promisingly employed as a toughened plastic and vibrational damper in a wide service range with excellent thermal stability,...
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Comprehensive Enhancement of Prepolymer-Based Flexible Polyurethane Foams’ Performance by Introduction of Cost-Effective Waste-Based Ground Tire Rubber Particles
PublicationMaterial innovations in polyurethane (PU) foams should ideally combine performance enhancement, environmental impact limitation, and cost reduction. These goals can be achieved by applying recycled or waste-based materials without broader industrial applications, implicating their low price. Herein, from 5 to 20 parts by weight of ground tire rubber (GTR) particles originated from the recycling of postconsumer car tires were incorporated...
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Mechanical and thermo-mechanical properties of natural rubber composites filled with submicron- and nano-sized silica particles and prepared using glycolysate as a plasticizer
PublicationThe main aim of this work was to examine the selected mechanical and thermo-mechanical properties of natural rubber/silica composites prepared using glycolysate as a plasticizer. Prepared composites contained different amounts of submicron- (10, 15, 20 or 25 pphr) or nano-particles (0.5, 0.75, 1.0 or 1.25 pphr). The tensile properties, tear resistance, hardness, abrasion resistance and resilience of prepared materials were determined....
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Ground Tire Rubber Modified by Elastomers via Low-Temperature Extrusion Process: Physico-Mechanical Properties and Volatile Organic Emission Assessment
PublicationIn this paper, low-temperature extrusion of ground tire rubber was performed as a proecological waste tires recycling method. During this process, ground tire rubber was modified with constant content of dicumyl peroxide and a variable amount of elastomer (in the range: 2.5–15 phr). During the studies, three types of elastomers were used: styrene-butadiene rubber, styreneethylene/butylene-styrene grafted with maleic anhydride and...
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The impact of filler thermomechanical modifications on static and dynamic mechanical performance of flexible foamed polyurethane/ground tire rubber/zinc borate composites
PublicationThe rapid development of the automotive industry is very beneficial to many aspects of human life, but it is also a very significant environmental burden. The most straightforward impact is related to the generation of exhaust, but the management of post-consumer car parts is also a major challenge. Among them, waste tires are very burdensome due to their enormous numbers. Therefore, it is essential to develop novel, environmentally...
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Influence of hydrostatic pump operation period on performance of a thrust bearing of a 125 MW pump-turbine
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Evaluation of water turbine hydrodynamic thrust bearing performance on the basis of thermoelastohydrodynamic calculations and operational data
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Vibration-Based Diagnostics of Radial Clearances and Bolts Loosening in the Bearing Supports of the Heavy-Duty Gearboxes
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The influence of strain on the Verwey transition as a function of dopant concentration: towards a geobarometer for magnetite-bearing rocks
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High-precision bearing estimation for active sonar with cylindrical array performed by interpolated array transformation
PublicationThe article presents a method for improving the accuracy of bearing in multibeam sonar with a cylindrical array. The antenna’s non-linear shape and the resulting non-uniform sampling of the signal in space, mean that known methods of high-resolution spectral analysis cannot be used. In order to apply an algorithm from this group, a linear virtual antenna must be produced. The paper presents a technique of mapping a cylindrical...
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Analysis of pavement structure sensitivity to passage of oversized heavy duty vehicle in terms of bearing capacity
PublicationOversized heavy duty vehicles occur in traffic very rarely but they reach extremely high weights, even up to 800 tonne. The detrimental impact of these vehicles on pavement structure is much higher than in case of commercial vehicles that comprise typical traffic, thus it is necessary to assess the sensitivity of pavement structure to passage of oversized vehicles. The paper presents results of sample calculations of load equivalency factor...
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Assessment of possible application of water lubricated sintered brass slide bearing for marine propeller shaft
PublicationW artykule przedstawiono wyniki badań eksperymentalnych smarowanego wodą łożyska poprzecznego z panwią wykonaną ze spieku brązu.Przedstawiono wyniki pomiarów rozkładu ciśnienia w filmie smarnym, trajektorie osi wału oraz oporów ruchu.Przeprowadzono ocenę przydatności tego typu łożyska do łożyskowania okrętowych wałów śrubowych.
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Comparison of induction motor bearing diagnostic test results through vibration and stator current measurement
PublicationThe paper discusses results of tests performed by authors, related to the angine bearings diagnostic using vibration and stator current measurements. The paper contains the description of an automatic measurement system, developed for measurement of those harmonics and processing that to obtain bearing diagnostic information. System was tested on objects with intentionally made defects in bearings, results of this test was also...
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Justifying the prolongation of the service life of the bearing structure of a tank car when using Y25 bogies
PublicationThis paper substantiates the use of Y25 bogies under tank cars in order to prolong their service life. The reported study has been carried out for a tank car with rated parameters, as well as the actual ones, registered during full-scale research. Mathematical modeling was performed to determine the basic indicators of the tank car dynamics. The differential equations of motion were solved by a Runge-Kutta method using the Mathcad...
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Evaluation of water turbine hydrodynamic thrust bearing performance on the basis of thermoelastohydrodynamic calculations and operational data.
PublicationW pracy przedstawiono analizę konstrukcji łożyska wzdłużnego turbiny wodnej. Łożysko zostało skonstruowane około 50 lat temu, a jego konstrukcja przewiduje kompensację termicznych odkształceń klocków. W analizie uwzględniono odkształcenia łożyska i wymianę ciepła w filmie smarowym i klockach łożyskowych. Poza obecną konstrukcją łożyska przeprowadzono również studium wpływu podstawowych parametrów konstrukcyjnych: grubości klocka...
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Influence of hydrostatic pump operation period on performance of a thrust bearing of a 125 MW pump-turbine.
PublicationW pracy przedstawiono wyniki badań eksploatacyjnych łożysk wzdłużnych pompoturbin 125 MW elektrowni szczytowo pompowej (esp) Żar. W celu oceny warunków pracy łożysk wyposażono je w segmenty pomiarowe umożliwiające pomiary temperatury i położenia segmentu. W pracy omówiono konstrukcję i wyposażenie segmentu badawczego, metodykę wyznaczania charakterystycznych wielkości. Omówiono także wyniki badań wpływu czasu pracy pompy hydrostatycznego...
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Stability and initial post-buckling behaviour of frame system with vertical bracings
PublicationStalowe hale są budowane jako układ ram płaskich połączonych stężeniami dachowymi i stężeniami pionowymi w postaci krzyżujących się prętów. W pracy przedstawiono analizę stateczności i zachowania pokrytycznego takiego układu poddanego działaniu obciążeń pionowych. Korzystając z warunków stacjonarności całkowitej energii potencjalnej wykazano, że punkt bifurkacji utraty stateczności jest niesymetryczny i niestateczny. Oznacza to,...