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Search results for: STABILITY ANALYSIS
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A Control Theoretical Approach to Spectral Factorization is Unstable
PublicationLocal stability analysis of a recently proposed recursive feedback-based approach to spectral factorization is performed. The method is found not to give stability guarantees. Interestingly enough, its global behavior often allows one to obtain reasonable approximations of spectral factorizations if a suitable stopping criterion is employed.
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Numerical analysis and in situ tests of the Grot Rowecki Bridge in Warsaw
PublicationThe paper presents the FEM analysis of the reconstructed the Grot-Rowecki Bridge over Vistula river in Warsaw. The bridge has seven spans and consists of two independent structures with the longest spans of 120 m. After reconstruction the bridge is over 10 m wider. The numerical, nonlinear analysis has been con-ducted on a global and local FEM models. These models are defined so as they strictly comply with global structural bridge...
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Stability of the FDTD scheme containing macromodels.
PublicationZaprezentowano analizę stabilnościową algorytmu różnic skończonych w dziedzinie czasu zawierającego makromodele. Pokazano, że dla uzyskania stabilnych makromodeli stabilność schematu FDTD połączonego z makromodelami zależy od sposobu przeprowadzenia interpolacji pól granicznych. Maksymalny dozwolony krok czasowy jest dużo większy niż dla subgriddingu.
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Effect of Silicone on the Collagen Fibrillogenesis and Stability
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Investigation of stability of ester-urethane prepolymers
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Model studies on then-alkane emulsions stability
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On the characteristic and stability of iron diet supplements
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Stability of Superhalogen Anions in the Aqueous Phase
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Vibrational properties and stability of FePt nanoalloys
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Structural Dynamics and Stability of Composite Structures
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THE PROBLEM OF THE BANKING SYSTEM STABILITY IN THE LITERATURE
PublicationThe article is an overview of the literature output in the field of banking sector stability. In the literature a plethora of definitions of the term may be encountered. There is no universal definition of the term. Therefore, the article proposes a unique division of the existing explanations into the following groups: stability determined by the quality of the banking sector, stability in terms of its influence on the macroeconomic...
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Selected problems of stability of steel structures.
PublicationW pracy przedstawiono wyniki badań dotyczących stateczności wybranych konstrukcji stalowych. Prezentowane rozważania są oparte na klasycznych założeniach teorii prętów cienkościennych o nieodkształcalnym przekroju poprzecznym. Wyznaczono pierwszą wariację sił krytycznych pręta cienkościennego o bisymetrycznym otwartym przekroju poprzecznym uwzględniając następujące zmienne projektowe: ⎯wymiary przekroju poprzecznego, ⎯ charakterystyki...
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Comparison of buckling resistance of columns modelled by beam and shell elements using non-linear analysis
PublicationThe aim of the paper is to investigate the stability process in the axially compressed columns modelled by beam and shell elements using static and dynamic finite element analysis by taking both the geometric and material non-linearity into account. The perfect columns and columns with geometric imperfections were analysed. The differences between the results of static and dynamic analyses in shell and beam models were discussed.
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Computer-aided analysis of resonance risk in power system with Static Var Compensators
PublicationStatic Var Compensators operation in a power system may significantly improve voltage profiles in nodes and the reactive power balance, as well as ensure greater system stability in emergency conditions. However these devices may be a cause of a resonance in the system. The aim of this paper is to call attention to the need to include resonance phenomena in a compensator’s location evaluation process. The analysis performed in...
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Fully bio-based poly(propylene succinate) synthesis and investigation of thermal degradation kinetics with released gases analysis
PublicationOne of the most important information about polyesters is their thermal stability and phase transition tem- peratures. These characteristics give information about the promising behavior of the polyester during proces- sing. In this work, linear bio-based polyester polyols were prepared with the use of succinic acid and 1.3- propanediol (both with natural origin). As a polycondensation catalyst was used tetraisopropyl orthotitanate...
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Investigation of buckling resistance of columns using non-linear static and dynamic analysis
PublicationThe aim of this paper is to investigate the stability process in an axially compressed column using a static and dynamic finite element analysis by taking both the geometric and material non-linearity into account. The perfect column and column with geometric imperfections were analysed. The linear buckling analyses were used to obtain the lowest buckling load and shapes of buckled forms that were taken into account as initial...
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Buckling Analysis of Cold Formed Silo Column
PublicationThe paper is devoted to stability analysis of different models of steel cold formed silo column. The steel cylindrical silos are often composed of corrugated walls and vertical open-sectional columns uniformly placed along the silo circumference. Both the whole 3D silo, a simplified model consisting of one column with a part of the silo walls, and a single column resting on elastic foundation provided by the silo walls were analyzed....
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Comparison of oxidative stability of different edible oils
PublicationCelem prezentowanych badań było porównanie stabilności oksydacyjnej olejów roślinnych z Polski, Finlandii i Hiszpanii. Na etapie przyspieszania utleniania zastosowano promieniowanie ultrafioletowe (UV). Po naświetlaniu olejów powstałe związki lotne ekstrahowano z fazy nadpowierzchniowej za pomocą techniki mikroekstrakcji do fazy stacjonarnej (HS-SPME) i analizowano z zastosowaniem chromatografu gazowego z detektorem płomieniowo-jonizacyjnym...
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Thermal stability of the cobalt base clad layers
PublicationBadano wpływ długotrwałego oddziaływania temperatury na mikrostrukturę i własności mechaniczne warstw napawanych laserowo wykonanych ze stopów na bazie kobaltu zawierających chrom i wolfram. Stopy te są przewidywane do zastosoania na przylgnie zaworów wydechowych silników diesla.
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Stability of free floating ship. Part II
PublicationJest to część II artykułu, którego I część ukazała się w PMR 2/2005. Ramiona prostujące są niejednoznaczne dla statku swobodnego, bowiem zależą od sposobu działania momentu przechylającego. Omówiono dwa przypadki, gdy moment przechylający jest równoległy do płaszczyzny symetrii statku oraz gdy wykonuje najmniejszą pracę, czyli gdy jest równoległy do głównej osi bezwładności wodnicy pływania. Pokazano, że przemieszczenia kątowe...
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Investigations of transverse stability of semi-displacement ships
PublicationPrzedstawiono 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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The measurement of conformational stability of proteins adsorbed on siloxanes
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Thermal stability of expanded perlite modified by mullite
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Dynamics and stability of icosahedral Fe–Pt nanoparticles
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Thermodynamic properties and phase stability of wadsleyite II
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The Stability of 4‐Chloromethcathinone in Blood and Vitreous Humor
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Recent breakthroughs in the stability testing of pharmaceutical compounds
PublicationPharmaceutical development is mostly focused on the research leading to approval of a new and viable active substance. However, there is a number of old generation compounds that are still being used in contemporary medicinal practice. So that new analytical developments should cover not only the safety of newly developed drug substances, which is obvious, but should also be directed into the search of individual stability issues...
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A history of the physical and chemical stability of pharmaceuticals : a review
Publication: There is a great need for a broad range review of stability tests of active pharmaceutical ingredients (APIs) in comparison with current requirements contained in the pharmacopoeia. This review focuses on a pharmaceutical history of physical and chemical stability determination. Traditional knowledge must be considered in the context of physical stability, while new knowledge must be applied and acquired in terms of identification...
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Wind farms influence on power system stability
PublicationW artykule przedstawiono analizę wpływu elektrowni i farm wiatrowych na stabilność systemu elektroenergetycznego. Pokazano wyniki pomiarów modów kołysań elektromechanicznych wykonanych w rzeczywistym systemie elektroenergetycznym.
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A New Approach to Stability Evaluation of Digital Filters
PublicationIn this paper, a new numerical method of evaluating digital filter stability is presented. This approach is based on novel root-finding algorithms at the complex plane using the Delaunay triangulation and Cauchy's Argument Principle. The presented algorithm locates unstable zeros of the characteristic equation with their multiplicities. The proposed method is generic and can be applied to a vast range of systems. Verification of...
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Weak Stability of Centred Quadratic Stochastic Operators
PublicationWe 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
PublicationWe 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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Stability of free floating ship. Part I
PublicationSformułowano problem obliczeń ramion prostujących statku swobodnie pływającego, tj. wzdłużnie zrównoważonego przy każdym kącie przechyłu. Ramiona prostujące są niejednoznaczne w takim wypadku, zależą bowiem od sposobu działania momentu przechylającego. Omówiono dwa przypadki, gdy moment przechylający jest równoległy do płaszczyzny symetrii statku, oraz gdy wykonuje najmniejszą pracę, czyli gdy jest równoległy do głównej osi bezwładności...
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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
PublicationA 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
PublicationAn 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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Computational analysis of substituent effects on proton affinity and gas-phase basicity of TEMPO derivatives and their hydrogen bonding interactions with water molecules
PublicationThe 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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MEMORY EFFECT ANALYSIS USING PIECEWISE CUBIC B-SPLINE OF TIME FRACTIONAL DIFFUSION EQUATION
PublicationThe 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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Stability criteria as constraints in a fleet of ships optimisation problem
PublicationRozwiązano 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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Surprising Radiolytic Stability of 8‑Thiomethyladenine in an Aqueous Solution
Publication8-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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Transient stability improvement of turbogenerator using fuzzy control.
PublicationW 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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Power System Dynamics. Stability and Control. 3rd edition
PublicationComprehensive, 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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In Vitro Measurement of Conformational Stability of Fibrinogen Adsorbed on Siloxane
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Motion stability during optimal control of the mobile platform
PublicationPraca 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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Structural stability of invariant sets of vibro-impact systems
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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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Porous nanopeapod Pd catalyst with excellent stability and efficiency
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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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Anatomical and Clinical Implications in Neocondyle Stability After a Condylectomy
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