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Search results for: disc spring
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Emission Profiles of Volatiles during 3D Printing with ABS, ASA, Nylon, and PETG Polymer Filaments
PublicationIn this short communication we characterize the emission of volatile organic compounds (VOCs) from fused filament fabrication (FFF) 3D printing using four polymer materials, namely polyethylene terephthalate glycol-modified (PETG), acrylonitrile styrene acrylate (ASA), Nylon, and acrylonitrile butadiene styrene (ABS). Detailed emission profiles are obtained during thermal degradation of the polymers as a function of temperature...
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Adjusting the Stiffness of Supports during Milling of a Large-Size Workpiece Using the Salp Swarm Algorithm
PublicationThis paper concerns the problem of vibration reduction during milling. For this purpose, it is proposed that the standard supports of the workpiece be replaced with adjustable stiffness supports. This affects the modal parameters of the whole system, i.e., object and its supports, which is essential from the point of view of the relative tool–workpiece vibrations. To reduce the vibration level during milling, it is necessary to...
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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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Optimum shapes and dimensions of rubber bumpers in order to reduce structural pounding during seismic excitations
PublicationLarge displacement of structures observed during seismic excitations may lead to collisions between two adjacent, insufficiently-separated buildings and may result in major damages of both of them. In many building codes, appropriate equations or approximately recommended distances between structures in order to avoid pounding hazard have been introduced. Unfortunately, further, more detailed considerations show that safety situation...
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Which Curve Fits Best: Fitting ROC Curve Models to Empirical Credit-Scoring Data
PublicationIn the practice of credit-risk management, the models for receiver operating characteristic (ROC) curves are helpful in describing the shape of an ROC curve, estimating the discriminatory power of a scorecard, and generating ROC curves without underlying data. The primary purpose of this study is to review the ROC curve models proposed in the literature, primarily in biostatistics, and to fit them to actual credit-scoring ROC data...
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ESG investing during the Covid-19 crisis. Evidence from Central European Stock Exchanges
PublicationAs COVID-19 turned into a global pandemic, world markets gradually began to recover after initial dynamic declines. Restrictions, and their subsequent loosening, were, and are, not without significance for the financial markets. These particular circumstances provide a unique opportunity to contribute to the literature by focusing on the potential resilience of ESG (environmental, social and governance) investing in an era of crisis....
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Safeguarding democracy during pandemics. Social distancing, postal, or internet voting—the good, the bad, or the ugly?
PublicationDuring a pandemic, many countries and organizations must decide whether to postpone upcoming elections or to hold them (Krimmer et al., 2020a). If the decision is made to hold the election, three main scenarios come to mind: continue using the existing system but include measures to ensure the health of participants; or look for alternatives among remote voting channels which could ensure social distancing is guaranteed either...
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Tacit knowledge acquisition & sharing, and its influence on innovations: A Polish/US cross-country study
PublicationThis study measures the relationship between tacit knowledge sharing and innovation in the Polish (n=350) and US (n=379) IT industries. Conceptually, the study identifies the potential sources of tacit knowledge development by individuals. That is, the study examines how “learning by doing” and “learning by interaction” lead to a willingness to share knowledge and, as a consequence, to support process and product/service innovation....
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Connected early-career experiences of equality in academia during the pandemic and beyond: Our liminal journey
PublicationIn this paper, we draw on our subjective experiences as two female early-career academics during the global COVID-19 pandemic. While we acknowledge that the pandemic had negative implications for many female scholars due to compulsory telework or increased family responsibilities, we also want to shed light on the empowering experiences shaped by collegial support that became an important part of our pandemic story. We build on...
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Real-time monitoring of volatiles and particles emitted from thermoplastic filaments during 3D printing
PublicationPresentation on the use of instrumental analytical techniques for the assessment of emission of volatiles and particulates during fdm 3d printing.
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Validation of Hydraulic Mechanism during Blowout Trauma of Human Orbit Depending on the Method of Load Application
PublicationThe more we know about mechanisms of the human orbital blowout type of trauma, the better we will be able to prevent them in the future. As long as the buckling mechanism’s veracity is not in doubt, the hydraulic mechanism is not based on equally strong premises. To investigate the correctness of the hydraulic mechanism’s theory, two different methods of implementation of the hydraulic load to the finite element method (FEM) model...
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Comparison of the fracture toughness of pine wood determined on the basis of orthogonal linear cutting and frame sawing
PublicationIn this paper, the values of the fracture toughness of Scots pine determined by cutting tests are presented. The cutting tests were carried out using the samples of Scotch pine (Pinus sylvestris L.) from Pomeranian Region, Poland. These experiments were carried out on two research stands: orthogonal linear cutting tests were conducted using the microtome instrument and the frame saw PRW-15M was used for sawing tests. The values...
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Elemental and water-insoluble organic carbon in Svalbard snow: a synthesis of observations during 2007–2018
PublicationLight-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplifying Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007...
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Real-time monitoring of volatiles and particles emitted from thermoplastic filaments during 3D printing
PublicationThe proliferation of consumer-grade three-dimensional (3D) printers using fused deposition, also known as fused filament fabrication, has given rise to concerns over the exposure of users to potentially harmful substances. Thermoplastic filaments made of different polymers are extruded through a heated printer nozzle and deposited layer by layer on a build platform to form the printed object. This process leads to the emission...
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Cure Index demonstrates curing of epoxy composites containing silica nanoparticles of variable morphology and porosity
PublicationAn image was taken by Cure Index on curability of epoxy with silica nanoparticles having variable morphology and porosity. Three kinds of silica nanoparticles with non-porous curved-rod, non-porous spherical, and mesoporous spherical microstructures were synthesized and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM) and Brunauer–Emmett–Teller analyses. Epoxy nanocomposites containing...
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The analysis of temperature changes of the saliva traces left on the fur during laboratory rats social contacts
PublicationAutomatic analysis of complex rodent social be- havior, especially aggressive ones, is of important scientific interest. In this paper we analyze the properties of the data created as a result of aggressive rodent social behavior. Detec- tion of specific aggressive behaviors is based on the event of leaving traces of saliva on the fur of the attacked individual, which are clearly visible in the thermal imaging. The traces change...
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Experimental studies on the impact of changing the pipe material on the propagation of the pressure wave during water hammer
PublicationAim of the paper is to present the results studying the water hammer phenomenon in pipes made of different materials, and to show the impact of changing the type of material of the pipe on the velocity of the pressure wave during the transient flow in the pipes. In terms of research material and methods, pipes made of galvanized steel and high-density polyethylene were tested. Measurements were made using strain gauges with a high...
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Hydraulic analysis of causes of washout of Gdynia-Orłowo seashore during the flood in the Kacza river estuary
PublicationIn July 2016 in the Three-city agglomeration a rainfall episode of over a day duration and 150 mm summary rainfall height, occurred. This situation, extreme as for Polish conditions, caused significant freshets in rivers and streams running into Gdansk Bay, the Baltic Sea, and serving as collectors of rainfall waters for the sea-coast towns. In many areas of the Three-city flood phenomena and overflows took place. The flood also...
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Channel Blockage and Flow Maldistribution during Unsteady Flow in a Model Microchannel Plate heat Exchanger
PublicationThis paper describes the problem of channel blockage as a result of flow maldistribution between the channels of a model mini channel plate heat exchanger consisting of one pass on each leg. Each leg of the heat exchanger contains 51 parallel and rectangular minichannels of four hydraulic diameters namely 461 μm, 571 μm, 750 μm and 823 μm. In addition, a more complex geometry has been investigated where for the sake of breaking...
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Curing epoxy with ethylenediaminetetraacetic acid (EDTA) surface-functionalized Co Fe3-O4 magnetic nanoparticles
PublicationIn this work, the bulk and surface composition of Fe3O4 supermagnetic nanoparticles were modified for efficient epoxy curing. The bare, ethylenediaminetetraacetic acid (EDTA) capped, and cobalt (Co)-doped EDTA capped Fe3O4 nanoparticles were synthesized electrochemically. The crystalline structure and phase information, surface capping, morphology and magnetization behavior of nanoparticles were studied by X-Ray diffraction (XRD),...
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GTR/NBR/Silica Composites Performance Properties as a Function of Curing System: Sulfur versus Peroxides
PublicationIn this work, conventional sulfur and two types of organic peroxides (dicumyl peroxide (DCP) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB)) curing systems were used to investigate the possibility for tailoring of the performance properties of GTR/NBR blends reinforced with a variable content of highly dispersive silica (0–30 phr). The curing characteristics, static mechanical and acoustical properties, swelling behavior,...
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Natural Products Counteracting Cardiotoxicity during Cancer Chemotherapy: The Special Case of Doxorubicin, a Comprehensive Review
PublicationCardiotoxicity is a frequent undesirable phenomenon observed during oncological treatment that limits the therapeutic dose of antitumor drugs and thus may decrease the effec-‐‑ tiveness of cancer eradication. Almost all antitumor drugs exhibit toxic properties towards cardiac muscle. One of the underlying causes of cardiotoxicity is stimulation of oxidative...
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Unsupervised machine-learning classification of electrophysiologically active electrodes during human cognitive task performance
PublicationIdentification of active electrodes that record task-relevant neurophysiological activity is needed for clinical and industrial applications as well as for investigating brain functions. We developed an unsupervised, fully automated approach to classify active electrodes showing event-related intracranial EEG (iEEG) responses from 115 patients performing a free recall verbal memory task. Our approach employed new interpretable...
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The clamping selection method to reduce the vibration of large-size workpieces during the face milling process
PublicationThe article introduces a method for selecting the best clamping conditions to obtain vibration reduction during milling of large-size workpiece. It is based on experimental modal analysis performed for a set of assumed, fixing conditions of a considered workpiece to identify Frequency Response Functions (FRFs) for each tightening torque of the mounting screws. Simulated plots of periodically changing nominal cutting forces are...
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Reduction of vibration level by the spindle speed optimisation during ball end milling of flexible details
PublicationPraca dotyczy nadzorowania drgań podczas skrawania przedmiotów podatnych frezem kulistym. Przedsatwiono wspomaganą komputerowo procedurę nadzorowania z optymalizacją prędkości obrotowej narzędzia. Przy modelowaniu wykorzystano niestacjonarny model obliczeniowy. Rezultatem modelowania jest układ hybrydowy, w którym oddzielono podukłady: modalny, łączący i strukturalny. Metoda wymaga identyfikacji częstości własnych co może być wykonane...
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A new method of ergonomic testing of gloves protecting against cuts and stabs during knife use
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Application of electrical capacitance tomography (ECT) to measurement of sand concentration changes during silo flow
PublicationW artykule przedstawiono wyniki doświadczeń pomiaru zmian koncentracji materiału granulowanego podczas przepływu silosowego. Zmiany zostały pomierzone przy pomocy tomografu. Doświadczenia wykonano w silosie cylindrycznym dla 2 różnych szorstkości ścian.
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Deterministic and statistical size effect during shearing of granular layer within a micro-polar hypoplasticity
PublicationArtykuł omawia deterministyczny i statystyczny efekt skali w materiałach granulowanych podczas ścinania cienkiej warstwy piasku między dwoma bardzo szorstkimi ścianami. Obliczenia wykonano metodą elementów skończonych na bazie mikropolarnego prawa hipoplastycznego. Przyjęto różne metody redukujące ilość realizacji pól losowych dla początkowego wskaźnika porowatości..
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FE-investigations on crack spacing in reinforced concrete beams within non-local continuum mechanics.
PublicationW artykule przedstawiono wyniki numerycznej analizy rozstawu rys w belkach żelbetowych przy zastosowaniu dwóch ciągłych modeli nielokalnych. Zbadano wpływ wielu różnych parametrów na rozstaw rys.
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Application of inserts for suppression of coupled dynamic-acoustic effects during confined granular flow in silos
PublicationArtykuł omawia sposoby redukcji efektów dynamiczno-akustycznych w silosach. Do redukcji zastosowano różne wkładki. Zbadano wpływ kształtu i liczby wkładek w doświadczeniach. Na podstawie wyników doświadczalnych opracowano metodę redukcji efektów dynamiczno-akustycznych w dużych stalowych silosach.
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Experimental and numerical investigations of concrete behaviour at meso-level during quasi-static splitting tension.
PublicationArtykuł omawia wyniki numeryczne dotyczące pękania betonu uzyskane stosując metodę elementów dyskretnych. Dwuwymiarowe obliczenia wykonano dla próbek betonowych podczas rozłupywania. Beton został opisany jako model 4-fazowy. Mikrostruktura betonu odpowiadała zdjęciom tomograficznym. Zbadano wpływ warunków brzegowych na proces pękania. W obliczeniach zwrócono uwagę na porzebieg zjawisk mikrostrukturalnych przebieg pękania. Wyniki...
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EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF CONCRETE BEHAVIOUR AT MESO-LEVEL DURING QUASI-STATIC SPLITTING TENSION
PublicationThe paper describes experimental and numerical results of quasi-static splitting tensile tests on concrete specimens at meso-scale level. The loading strip was made of plywood or steel. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: 3D x-ray micro-computed tomography, 2D scanning electron microscope and manual 2D digital microscope. The discrete element method was used to directly...
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Finite element study of patterns of shear zones in granular bodies during plane strain compression
PublicationW artykule przedstawiono obliczenia efektów skali na nośność fundamentu na piasku. Obliczenia wykonano przy pomocy mikropolarnego prawa hipoplastycznego. W obliczeniach wykorzystano stochastyczne rozkłady początkowego wskaźnika porowatości według rozkładu Gaussa.
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Investigations of shear localization during granular silo flow with non-local hypoplastic Constitutive Model
PublicationW artykule przedstawiono wyniki numerycznej analizy lokalizacji odkształceń w materiałach granulowanych podczas przepływu w silosach. Obliczenia wykonano przy zastosowaniu metody elementów skończonych w podejściu ALE i mikropolarnego modelu hipoplastycznego. Pokazano wpływ szorstkości ścian silosu i zagęszczenia materiału sypkiego na typ lokalizacji.
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Modeling of shear localization during confined granular flow in silos within non-local hypoplasticity.
PublicationW artykule przedstawiono wyniki numerycznej analizy lokalizacji odkształceń w materiałach granulowanych podczas przepływu w silosach. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i mikropolarnego modelu hipoplastycznego. Zastosowano podejście ALE. Pokazano wpływ szorstkości ścian silosu i zagęszczenia materiału sypkiego na typ lokalizacji.
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Application of the 3D DEM in the modelling of fractures in pre-flawed marble specimens during uniaxial compression
PublicationPrzedstawiono w tym artykule wyniki modelowania pęknięć w cylindrycznych próbkach marmurowych ze wstępnymi nacięciami w czasie jednoosiowego ściskania . Zastosowano metodę elementów dyskretnych (DEM). Zbadano propagację i koalescencję pęknięć w próbkach marmuru z istniejącymi otwartymi nacięciami pod różnymi kątami do poziomu. Wyniki numerycznych symulacji trójwymiarowych (3D) zostały bezpośrednio porównane z badaniami laboratoryjnymi....
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Application of Multivariate Adaptive Regression Splines (MARSplines) for Predicting Hansen Solubility Parameters Based on 1D and 2D Molecular Descriptors Computed from SMILES String
PublicationA new method of Hansen solubility parameters (HSPs) prediction was developed by combining the multivariate adaptive regression splines (MARSplines) methodology with a simple multivariable regression involving 1D and 2D PaDEL molecular descriptors. In order to adopt the MARSplines approach to QSPR/QSAR problems, several optimization procedures were proposed and tested. The effectiveness of the obtained models was checked via standard...
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Analysis of different tillage implements with respect to reduced fuel consumption, tractor operating speed and its wheel slippage
PublicationNowadays the prices of agricultural farm produced products are increasing with ant-speed and the prices of input for raising crops are increasing with rocket-speed. Therefore, there is a dire need to conduct some important studies to innovate the techniques which can lower the costs of crop production. In this context, this study was conducted to evaluate the consumption of fuel at different tillage implements, tractor operating...
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Assessment of the results of surgical treatment and postoperative physiotherapy in patients with degenerations of the cervical spine
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Analysis of the Possibilities of Applying 3D Print Methods for the Needs of Ship-Building Industry
PublicationArticle presents the analysis of applying additive and hybrid manufacturing methods and its impact on dynamic stiffness of prepared samples. Dynamic analysis of the handle bracket specimens consisted in plotting the resonance curves and using these curves to estimate the dynamic stiffness of elements produced with additive manufacturing technology. Authors focused especially on 3D print in Fused Deposiotion Modeling/Fused Filament...
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Biomechanics of Lumbar Spine Injury in Road Barrier Collision–Finite Element Study
PublicationLiterature and field data from CIREN database have shown that lumbar spine injuries occur during car crashes. There are multiple hypotheses regarding how they occur; however, there is no biomechanical explanation for these injuries during collisions with road safety barriers (RSBs). Therefore, the objective of this study was to investigate the mechanics of vertebral fractures during car collisions with concrete RSBs. The finite...
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A six-ring probe for monitoring conductivity changes
Publicationstreszczenie: W pracy przedstawiono konstrukcję sondy szściopierścieniowej do monitorowania zmian immitancji. Zdefiniowano czułość sondy i przedstawiono jej rozkład dla przypadków izotropowych i anizotropowych. Teoretyczne symulacje za pomocą metody elementów skończonych zostały zweryfikowane eksperymentalnie, za pomocą specjalnie skonstruowanego zestawu pomiarowego. Zamieszczono przykładowe pomiary in vivo.
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A ring-based probe for determination of the skin conductivity
PublicationW pracy przedstawiono konstrukcję sondy do pomiarów przewodności skóry wstanie oparzenia.
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Some remarks on the Euler ring U(G)
PublicationNiech G będzie zwartą grupą Liego i niech U(G) oznacza pierściń Eulera G skonstruoawany przez tom Diecka w [5,6]. Główny wynikpracy (Twierdzenie 4.1) opisuje homomorfizm pierścienia U(SO(3)) w pierścień U(SO(2))indukowany przez włożenie grupy SO(2) w grupę SO(3).
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Kagome Lattice Promotes Chiral Spin Fluctuations
PublicationDynamical spin fluctuations in magnets can be endowed with a slight bent toward left- or right-handed chirality by Dzyaloshinskii-Moriya interactions. However, little is known about the crucial role of lattice geometry on these chiral spin fluctuations and on fluctuation-related transport anomalies driven by the quantum-mechanical (Berry) phase of conduction electrons. Via thermoelectric Nernst effect and electric Hall effect experiments,...
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Wideband crossover structure with double ring resonators
PublicationThe structure of a four-port microstrip crossover is presented. The device is composed of two ring resonators, one circular and one built from meander lines, connected by four straight lines. The equivalent circuit model of the crossover is derived. The structure is designed on thin and flexible substrate to allow it to bend. The possibility of applying the device on curved surfaces is tested experimentally.
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Routing equal-size messages on a slotted ring
PublicationAnalizujemy problem routingu wiadomości w sieci slotted ring, biorąc pod uwagę dwa kryteria optymalizacyjne: długość uszeregowania oraz liczbę 'cykli' pracy sieci. Optymalny routing dla wiadomości o rozmiarze k jest silnie NP-trudny, natomiast dla k=q, gdzie q jest rozmiarem sieci, można obliczyć w czsie O(n^2log n) dla pierwszego kryterium. Podajemy również algorytm o czasie działania O(nlog n) oraz o stałym współczynniku dobroci....
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Objectivity in the non-Markovian spin-boson model
PublicationObjectivity constitutes one of the main features of the macroscopic classical world. An important aspect of the quantum-to-classical transition issue is to explain how such a property arises from the microscopic quantum theory. Recently, within the framework of open quantum systems, there has been proposed such a mechanism in terms of the so-called spectrum broadcast structures. These are multipartite quantum states of the system...
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Microwave Ring Resonator Based Pressure Sensor
PublicationThis paper demonstrates a microwave pressure sensor, which is based on microstrip line-fed ring resonators. The first ring resonator is loaded with the concentric cylindrical shafts, while the same number of the hollow shanks as the shafts are mounted on the second ring resonator. The arrangement of the cylindrical shaft and hollow shank allows for mechanical movement between two substrates while maintaining electrical contact....
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Vertical vibration reduction and audible sound analysis in surface grinding with electroplated tools
PublicationOne of the first approaches to the development of a grinding process monitoring system based on audible sound sensors is presented in the paper. Electroplated diamond tools (abrasive D64 and D107) were used in a modified single-disc lapping machine configuration for flat grinding of ceramics (Al2O3). The main aim of the machine modification was to reduce the vertical vibration in order to decrease the tool wear and to increase...