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Wyniki wyszukiwania dla: stability analysis
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Weak Stability of Centred Quadratic Stochastic Operators
PublikacjaWe consider the weak convergence of iterates of so-called centred quadratic stochastic operators. These iterations allow us to study the discrete time evolution of probability distributions of vector-valued traits in populations of inbreeding or hermaphroditic species, whenever the offspring’s trait is equal to an additively perturbed arithmetic mean of the parents’ traits. It is shown that for the existence of a weak limit, it...
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Stability and phase transition investigation of olanzapine polymorphs
PublikacjaWe use electrical embedded-fragment QM method with both DFT/ωB97XD/6-31G* and MP2/6-31G* to investigate the phase transformations of olanzapine. Gibbs free energy calculations predict that form I is always the most stable structure and form II is the least stable one, while form IV is more stable than form III below about 200 K but less stable above this temperature, implying a polymorphic phase transformation. This may account...
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Investigations of transverse stability of semi-displacement ships
PublikacjaPrzedstawiono wyniki eksperymentalnych badań modelowych poprzecznej stateczności jednostek półślizgowych, których celem było określenie wpływu prędkości oraz parametrów kształtu kadłuba na stateczność poprzeczną. Na podstawie wyników badań opracowano algorytmy, uwzględniające zmiany ramienia prostującego w funkcji prędkości, kąta przechyłu i parametrów geometrycznych kadłuba które mogą być wykorzystane do oceny stateczności poprzecznej...
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Novel 5-Substituted 2-(Aylmethylthio)-4-chloro-N-(5-aryl-1,2,4-triazin-3-yl)benzenesulfonamides: Synthesis, Molecular Structure, Anticancer Activity, Apoptosis-Inducing Activity and Metabolic Stability
PublikacjaA series of novel 5-substituted 2-(arylmethylthio)-4-chloro-N-(5-aryl-1,2,4-triazin-3-yl) benzenesulfonamide derivatives 27–60 have been synthesized by the reaction of aminoguanidines with an appropriate phenylglyoxal hydrate in glacial acetic acid. A majority of the compounds showed cytotoxic activity toward the human cancer cell lines HCT-116, HeLa and MCF-7, with IC50 values below 100 M. It was found that for the analogues 36–38...
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Quantification of Compatibility Between Polymeric Excipients and Atenolol Using Principal Component Analysis and Hierarchical Cluster Analysis
PublikacjaAn important challenge to overcome in the solid dosage forms technology is the selection of the most biopharmaceutically efficient polymeric excipients. The excipients can be selected, among others, by compatibility studies since incompatibilities between ingredients of the drug formulations adversely affect their bioavailability, stability, efficacy, and safety. Therefore, new, fast, and reliable methods for detecting incompatibility...
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Valorization of bio-based polyols synthesized via biomass liquefaction
Dane BadawczeAs the properties of polyols have a huge impact on the properties of manufactured polyurethanes, this study aims to determine the influence of polyethylene glycols with different molecular masses on the course of the biomass liquefaction process and bio-polyol properties. The obtained polyols were characterized by rheological studies. To confirm the...
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Computational analysis of substituent effects on proton affinity and gas-phase basicity of TEMPO derivatives and their hydrogen bonding interactions with water molecules
PublikacjaThe study investigates the molecular structure of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives in the gas phase using B3LYP and M06-2X functional methods. Intermolecular interactions are analyzed using natural bond orbital (NBO) and atoms in molecules (AIM) techniques. NO2-substituted TEMPO displays high reactivity, less stability, and softer properties. The study reveals that the stability of TEMPO derivatives...
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Solid Supports and New Advanced Materials used in Microextraction processes Metal-organic framework-based solid-phase microextraction for air samples analysis: a mini-review
PublikacjaSPME methods are now extremely popular. Recent advances in SPME have focused on the development of new materials as sorbent coatings capable of providing high extraction efficiencies, as well as high selectivity with high mechanical and chemical stability. Metal-organic frameworks (MOFs) have become an extremely popular material due to their unique properties (large surface area, selective gas adsorption, tunable structures, high...
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MEMORY EFFECT ANALYSIS USING PIECEWISE CUBIC B-SPLINE OF TIME FRACTIONAL DIFFUSION EQUATION
PublikacjaThe purpose of this work is to study the memory effect analysis of Caputo–Fabrizio time fractional diffusion equation by means of cubic B-spline functions. The Caputo–Fabrizio interpretation of fractional derivative involves a non-singular kernel that permits to describe some class of material heterogeneities and the effect of memory more effectively. The proposed numerical technique relies on finite difference approach and cubic...
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The buckling analysis of a cold-formed steel C-sectional column resting on an elastic foundation
PublikacjaThe paper is focused on stability analysis of different models of steel cold-formed C-section column. The analysed element may be applied as a primary load-bearing member in steel trusses or silo columns. The column can be used as a support for a wall of roof plates made of corrugated sheets. The wall sheeting that restrains the column against buckling may be considered as an elastic foundation. Due to the design solutions the...
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Motion stability during optimal control of the mobile platform
PublikacjaPraca przedstawia metodę badania stabilności robotów mobilnych podczas sterowania optymalnego na przykładzie 3-kołowej platformy mobilnej. Robot posiada więzy nieholonomiczne. Model matematyczny 3-kołowej platformy mobilnej opisuje skończona liczba nieliniowych równań różniczkowych. Stąd, prognozowanie stabilności ruchu takiego obiektu wymaga zastosowania efektywnych algorytmów.
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The influence of glycols on thermal stability and chemical structure of glycolysates
PublikacjaW pracy omówiono wpływ glikoli (etano-1,2-diolu - heksano-1,6-diolu) na właściwości termiczne oraz budowę chemiczną glikolizatów. Analizy przeprowadzono dla półproduktów wytworzonych w jednym stosunku masowym odpadowego poliuretanu do glikolu wynoszącego 10:1.
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On thermal stability of topological qubit in Kitaev's 4D model
PublikacjaWe analyse stability of the four-dimensional Kitaev model-a candidate for scalable quantum memory - in finite temperature within the weak coupling Markovian limit. It is shown that, below a critical temperature, certain topological qubit observables X and Z possess relaxation times exponentially long in the size of the system. Their construction involves polynomial in system size algorithm which uses as an input the results of...
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Porous nanopeapod Pd catalyst with excellent stability and efficiency
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Structural stability of invariant sets of vibro-impact systems
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Stability of Discrete Fractional Order State-space Systems
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Disinfection of rainwater as a way to their microbiological stability and safe use
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Chlorogenic Acid Stability in Pressurized Liquid Extraction Conditions
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Anatomical and Clinical Implications in Neocondyle Stability After a Condylectomy
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In Vitro Measurement of Conformational Stability of Fibrinogen Adsorbed on Siloxane
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Torsional Stability Assessment of Columns Using Photometry and FEM
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Stability of oil/water (ethanol, lysozyme or lysine) emulsions
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Prediction of the motion stability of three-wheel mobile robot
PublikacjaW pracy rozważa się projektowanie i realizację trajektorii ruchu 3-kołowego robota mobilnego, z uwzględnieniem jego kinematyki i dynamiki. Kołowe roboty mobilne zaliczane są do układów nieholonomicznych, w przypadku których przyjęte ograniczenia (więzy) dotyczą chwilowych prędkości punktów charakterystycznych układu. Model matematyczny obiektu przedstawiono w postaci skończonej liczby nieliniowych równań różniczkowych kinematyki...
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Transient stability improvement of turbogenerator using fuzzy control.
PublikacjaW artykule umówiono model rozmytego i adaptacyjnego układu regulacji turbogeneratora. Model ten składa się z: regulatora napięcia i stabilizatora systemowego. Parametry proponowanego modelu układu regulacji zostały zoptymalizowane wykorzystując algorytm genetyczny i są dostrajane w czasie pracy turbozespołu w celu uzyskania optymalnego stanu pracy. Przedstawiono badania symulacyjnych przejętego układu jednomaszynowego przy trójfazowym...
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Stability criteria as constraints in a fleet of ships optimisation problem
PublikacjaRozwiązano problem dotyczący matematycznej optymalizacji floty statków wielozadaniowych typu rzeka-morze, przeznaczonych dla europejskiej żeglugi przybrzeżnej i eksploatowanych w obszarze Mórz Północnego i Bałtyckiego, na poziomie zadania transportowego za pomocą metod programowania nieliniowego z ograniczeniami. Zaproponowano metodę włączenia istniejących kryteriów skuteczności statków jako ograniczeń w ogólnym modelu optymalizacji...
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The Influence of the Cuboid Float’s Parameters on the Stability of a Floating Building
PublikacjaUsually, the concept of sufficient stability of a floating structure is connected with the capacity to keep a small heel angle despite the moment of heeling. The variable responsible for these characteristics is the initial metacentric height, which is the relation between the hydrostatic features of the pontoon and the mass properties of the entire object. This article answers the questions of how heavy the floating system should...
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Power System Dynamics. Stability and Control. 3rd edition
PublikacjaComprehensive, state-of-the-art review of information on the electric power system dynamics and stability. It places the emphasis first on understanding the underlying physical principles before proceeding to more complex models and algorithms. The book explores the influence of classical sources of energy, wind farms and virtual power plants, power plants inertia and control strategy on power system stability. The book cover...
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Numerical Test for Stability Evaluation of Discrete-Time Systems
PublikacjaIn this paper, a new numerical test for stability evaluation of discrete-time systems is presented. It is based on modern root-finding techniques at the complex plane employing the Delaunay triangulation and Cauchy's Argument Principle. The method evaluates if a system is stable and returns possible values and multiplicities of unstable zeros of the characteristic equation. For state-space discrete-time models, the developed test...
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Selected Stability Problems of Thin-Walled Columns and Beams
PublikacjaThe article reviews a number of papers in the light of buckling analy- sis of thin-walled columns and beams. Stability of thin-walled columns and beams are considered a vital engineering science issue in both historical and present-day approaches. The paper refers to the recent authors’ works of the 2012–2019 period, published in leading journals. Similar review of stability problems of thin-walled structures developed at Gdansk...
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Surprising Radiolytic Stability of 8‑Thiomethyladenine in an Aqueous Solution
Publikacja8-Thiomethyladenine (ASCH3), a potentially radiosensitizing modified nucleobase, has been synthesized in a reaction between 8-thioadenine and methyl iodide. Despite favorable dissociative electron attachment (DEA) characteristics, the radiolysis of an aqueous solution of ASCH3 with a dose of X-ray amounting to as much as 300 Gy leads to no effects. Nevertheless, crossed electron-molecule beam experiments in the gas phase on ASCH3...
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Can we really solve an arch stability problem?
PublikacjaWe bring attention to the problem of solving nonlinear boundary-value problems for elastic structures such as arches and shells. Here we discuss a classical problem of a shear-deformable arch postbuckling. Considering a postbuckling behaviour of a circular arch we discuss the possibility to find numerically a solution for highly nonlinear regimes. The main attention is paid to the problem of determination of all solutions. The...
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Analysis of a gene expression model
PublikacjaWe study a mathematical model of gene transcription and protein synthesis with negative feedback. We consider a system of equations taking into account the number of active binding sites, the way in which dimers bind to DNA and time delay in translation process. For a simplified model that consist of three ordinary differential equations with time delay we derive conditions for stability of the positive steady state and for the...
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Energy landscape and structural transformations of C38 penta-fullerene: The stabilizing role of octagons and insights into penta-octa-penta-fullerene
PublikacjaTheoretical investigations were conducted to study the stability and energy landscape of C38 penta-fullerene, a structure comprising six penta-graphene unit cells. Vibrational analysis at the B3LYP/def2SVP level revealed 18 negative frequencies, indicating the dynamic instability of penta-fullerene. Analyzing the energy profiles for these vibrational modes led to the identification of six energetically favourable isomers, featuring...
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Development of a Response Assessment Tool for a Floating Dock System
PublikacjaDocking operations of ships require a response assessment to ensure structural and personnel safety. Environmental loads and improper ballast adjustments are the main threats to the docking operations. They can cause severe structural damages and stability loss to a floating dock system which includes a floating dock and a docked vessel, even if the velocities of the dock and the vessel are very low during the docking process....
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Geometrically nonlinear FEM analysis of FGM shells based on neutral physical surface approach in 6-parameter shell theory
PublikacjaThe paper presents the formulation of the elastic constitutive law for functionally graded materials (FGM) on the grounds of nonlinear 6-parameter shell theory with the 6th parameter being the drilling degree of freedom. The material law is derived by through-the-thickness integration of the Cosserat plane stress equations. The constitutive equations are formulated with respect to the neutral physical surface. The influence of...
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Experimental research of the stability of steel cylindricalshell subjected to circumferential compression
PublikacjaAt the Department of Metal Structures Gdańsk University of Technology, experiments have been performed on the stability of shell of steel cylindrical models. The experiments have been carried on a test bench built at the Department. The design based on other test benches which were created in the past by other scientists, where modernized by the courtesy of companies that offer modern solutions. The test bench enables to generate...
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The stability of a damaged roll-on roll-off vessel with water on deck
PublikacjaPrzeprowadzono analizę stateczności statku ro-ro w stanie awaryjnym z wodą na pokładzie. Pokazano, że moment przechylający związany jest z wypiętrzeniem wody na pokładzie ponad poziom wody zaburtowej, pochodzącym od fali. Omówiono trzy metody wyznaczania kąta przechyłu, wywołanego wodą na pokładzie. Zidentyfikowano krytyczne wypiętrzenie wody, przy którym następuje utrata stateczności statku.
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The work of Professor Andrzej Lasota on asymptotic stability and recent progress
PublikacjaPraca poświęcona jest wkładowi Profesora Andrzeja Lasoty w teorię asymptotycznej stabilności iteracji operatorów stochastycznych na przestrzeni ostatnich 36 lat. Podkreślono aplikacyjny charakter wyników, pokazując stosowne przykłady z modelowania rozwoju komórki, optymalizacji wierceń geologicznych i ewolucji modeli kwantowych.
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Real-Time stability monitoring for expansion of the UCTE synchronous area
PublikacjaW referacie przedstawiono zasady wykorzystania systemu WAMS dla potrzeb oceny zapasu stabilności lokalnej systemu elektroenergetycznego.
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Preliminary experimental research on stability of truss' joint with positive eccentricity
PublikacjaRecently, a very large interest in lightweight steel structures made from cold-formed sections has been noticeable. In the design practice, a large emphasis is put on rational shaping of both the thin-walled elements and constructions designed on them. The aim of this paper is to present the methodology for preparation of experimental research that model the behaviour of members in trusses made of cold-formed sections with positive...
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PI observer stability and application in an induction motor control system
PublikacjaThe paper discusses the problem of stability of a proportional-integral Luenberger observer, designated for the state variables reconstruction of a linear, time-invariant dynamical system.
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On convergence and stability of a numerical scheme of Coupled Nonlinear Schrödinger Equations
PublikacjaRozważamy rozwiązania numeryczne układu sprężynowych równań nieliniowych Schrödingera. Udowodniliśmy stabilność i zbieżność. Testujemy za pomocą rozwiązań solitonowych.
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Quantitative determination of mechanical stability in the novel coronavirus spike protein
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Magnetically induced dynamical stability of a Fe monolayer on W(110)
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Ridging, strength, and stability in high-resolution sea ice models
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N6-methyladenosine regulates the stability of RNA:DNA hybrids in human cells
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Effect of Newly Created Water Reservoirs on Agricultural Landscape Stability
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Wettability and Stability of Naproxen, Ibuprofen and/or Cyclosporine A/Silica Delivery Systems
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Stability Improvement of the Speed Observer of Induction Motor for Electric Vehicles
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Rheological properties and stability of water in Canola oil ethyl esteremulsion.
PublikacjaWyznaczono krzywe płynięcia i podatność na rozdział dla emulsji fazy wodnej w estrze etylowym oleju Canola. Właściwości te stanowią o podatności tej emulsji jako symulanta ropy naftowej w badaniach terenowych rozlewów olejowych.