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Wyniki wyszukiwania dla: VARIABLE KINEMATICS
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A New Approach for the Mitigating of Flow Maldistribution in Parallel Microchannel Heat Sink
PublikacjaThe problem of flow maldistribution is very critical in microchannel heat sinks (MCHS). It induces temperature nonuniformity, which may ultimately lead to the breakdown of associated system. In the present communication, a novel approach for the mitigation of flow maldistribution problem in parallel MCHS has been proposed using variable width microchannels. Numerical simulation of copper made parallel MCHS consisting of 25 channels...
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Models of Brushless Synchronous Generator for Studying Autonomous Electrical Power System
PublikacjaThis is a PhD dissertation. The work presented in this monograph was carried out at the Department of Power Electronics and Electrical Machines, Faculty of Electrical and Control Engineering at the Gdansk University of Technology. Developed during the research models of brushless synchronous generator ware verified using FEM based simulations and measurements conducted on the prototype generator. The main focus of the research...
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Is sequential batch reactor an efficient technology to protect recipient against non-steroidal anti-inflammatory drugs and paracetamol in treated wastewater?
PublikacjaThe tested facility was a wastewater treatment plant (WWTP) in Swarzewo, where the wastewater treatment takes place in aeration chambers with activated sludge using sequential batch reactors (SBRs). The concentration of the following pharmaceuticals: ibuprofen, paracetamol, flurbiprofen, naproxen, diclofenac, and its metabolites 5OH-diclofenac and 4OH-diclofenac was tested in influents and effluents. Simultaneously, the conventional...
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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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Effect of Simultaneous Valve Closures in Hydraulic Piping Systems
PublikacjaThe paper investigates wave interference (between pressure waves) occurring in simple hydraulic systems. Water hammer was induced by simultaneous closure of three valves located at the reservoirs of a “Y” type hydraulic system. Numerical simulations were carried out with the help of the freeware computer package Allievi enabling the reader to replicate results in a direct manner. The influence of the following quantities has been...
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Polynomial analysis as a new way of describing dynamic impedance spectra – Differential and relative impedance spectra
PublikacjaModel measurements of an equivalent electrical system were carried out using the technique of Dynamic Electrochemical Impedance Spectroscopy. The measurement took the form of potentiodynamic changes imposed on the tested system. Using the possibility of continuous impedance measurements, an attempt was made to develop an original and innovative method of analyzing impedance spectrograms, which is termed polynomial analysis. As...
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Simulation Environment in Python for Ship Encounter Situations
PublikacjaTo assess the risk of collision in radar navigation distance-based safety measures such as Distance at the Closest Point of Approach and Time to the Closest Point of Approach are most commonly used. Also Bow Crossing Range and Bow Crossing Time measures are good complement to the picture of the meeting situation. When ship safety domain is considered then Degree of Domain Violation and Time to Domain Violation can be applied. This...
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A hyperelastic model for soils with stress-induced and inherent anisotropy
PublikacjaIn this paper, modelling of the superposition of stress-induced and inherent anisotropy of soil small strain stiffness is8presented in the framework of hyperelasticity. A simple hyperelastic model, capable of reproducing variable stress-induced9anisotropy of stiffness, is extended by replacement of the stress invariant with mixed stress–microstructure invariant to10introduce constant inherent cross-anisotropic component. A convenient...
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Global value chains and wages under different wage setting mechanisms
PublikacjaThis study examines whether, and how, differences in wage bargaining schemes shape the relationship between global value chains (GVCs) and the wages of workers while considering both GVC participation and position in GVC. Our dataset is derived from the European Structure of Earnings Survey (SES), containing employee–employer data from 18 European countries, merged with sectoral data from the World Input-Output Database (WIOD)....
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Analysis of the Hydrodynamic Properties of the 3-Column Spar Platform for Offshore Wind Turbines
PublikacjaThe article presents a design of a floating platform for offshore wind turbines. The concept is a modification of the Spar design and consists of three variable section columns connected to each other by a ballast tank in the lower part of the platform. This solution makes it possible to influence the position of the centre of buoyancy and the centre of mass of the structure. Compared to the classic Spar platform structure, the...
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Understainding solid-phase microextraction: key factors influencing the extraction process and trends in improving the technique
PublikacjaAnalytical chemists are faced with the daunting challenges of accurately monitoring the state of the environment and the processes taking place in it and of determining an enormous range of analytes often present in trace and ultratrace amounts in sample matrixes with complex or variable compositions. Further challenges are presented by the need to introduce new methodologies into current analytical practice and equipment to comply...
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Experimental investigations and damage growth modeling of EN‐AW 2024 aluminum alloy under LCF loading accounting creep pre‐deformation
PublikacjaThis article presents the results of experimental tests of creep rupture and of low-cycle fatigue (LCF) of EN-AW 2024 aluminum alloy devoid of damage and having preliminary damage. The preliminary damage was dealt in the process of creep at elevated temperature 100C, 200C, and 300C until achievement of two different strain values at each temperature. Samples with preliminary damage were subjected to fatigue tests at room temperature....
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Efficient Multi-Objective Simulation-Driven Antenna Design Using Co-Kriging
PublikacjaA methodology for fast multi-objective antenna optimization is presented. Our approach is based on response surface approximation (RSA) modeling and variable-fidelity electromagnetic (EM) simulations. In the design process, a computationally cheap RSA surrogate model constructed from sampled coarse-discretization EM antenna simulations is optimized using a multi-objective evolutionary algorithm. The initially determined Pareto...
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Combination of hydrodynamic cavitation and SR-AOPs for simultaneous degradation of BTEX in water
PublikacjaHydrodynamic cavitation (HC) is an emerging technology gaining interest in water treatment for use in elimination of a wide range of organic pollutants. The energy released during cavitation phenomenon has number of applications and, particularly, it can be utilized for activation of persulfate (PS) and peroxymonosulfate (PMS). In the present study, hybrid techniques: HC combined with persulfates – HC-PS and HC-PMS were tested...
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Nonlinear Control of a Doubly Fed Generator Supplied by a Current Source Inverter
PublikacjaNowadays, wind turbines based on a doubly fed induction generator (DFIG) are a commonly used solution in the wind industry. The standard converter topology used in these systems is the voltage source inverter (VSI). The use of reverse-blocking insulated gate bipolar transistor (RB-IGBT) in the current source inverter topology (CSI), which is an alternative topology, opens new possibilities of control methods. This paper presents...
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Effective Air Quality Prediction Using Reinforced Swarm Optimization and Bi-Directional Gated Recurrent Unit
PublikacjaIn the present scenario, air quality prediction (AQP) is a complex task due to high variability, volatility, and dynamic nature in space and time of particulates and pollutants. Recently, several nations have had poor air quality due to the high emission of particulate matter (PM2.5) that affects human health conditions, especially in urban areas. In this research, a new optimization-based regression model was implemented for effective...
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Wykorzystanie Web 2.0 oraz architektury informacji w pracy brokera informacji.
PublikacjaThe development of information and communication technologies, dissemination of access as well as unlimited increase of publications result in the uncontrolled growth of knowledge resources. Looking up for the relevant information becomes increasingly difficult, especially when time plays a role. Such process requires vast knowledge, practical experience in obtaining and providing information and also analytical skills that...
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Rospuda - czy wszędzie budować mosty?
PublikacjaStreszczenie - SummaryThe article presents the problem of planning transport system in the areas of high natural and landscape values. Bridges and roads crossing valuable areas undergo Environmental Impact Assessment (EIA) Procedure. This procedure in Poland is often treated only as formal requirement, not as an instrument helping to solve conflicts and to minimise negative environmental and landscape effects. The potential of...
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Rating mathematical models for first-pass of tracer in pCT lung studies
PublikacjaThis paper presents a comparison of model based on the Gauss function and the most commonly used Gamma-variate model in perfusion computed tomography (pCT) lung studies. It also verifies whether used model affects value of blood volume parameter. Three mean concentration-time curves were created from actual pCT measurements: arterial input function, blood vessels in lungs and lung parenchyma. On the basis of these mean curves we...
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Analiza sterowania ułamkowego PIλDμ mocą reaktora jądrowego
PublikacjaW artykule przedstawiono syntezę regulatora PIλDμ niecałkowitego rzędu dla potrzeb sterowania mocą reaktora jądrowego lekko wodnego określanego, jako typu PWR (Pressurized Water Reactor). W tym celu wykorzystano nieliniowy model matematyczny reaktora PWR o parametrach skupionych obejmujący procesy generacji i wymiany ciepła oraz termicznych efektów reaktywnościowych. Nastawy regulatora PIλDμ niecałkowitego rzędu dobrano w sposób...
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Temperature Impact of Nitrogen Transformation in Technological System: Vertical Flow Constructed Wetland and Polishing Pond
PublikacjaThe article describes the results of the research, purpose of which was to evaluate influence of the temperature on the effectiveness of nitrification and denitrification in the sewage treatment system consisting of vertical flow constructed wetland and polishing pond. During the analysed period, the efficiency of removing total nitrogen was low and amounted to 12.7%. In the polishing pond in the summer period, content of total...
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Helicity discrimination in N,N'-dibenzoyl-1,2,3,4,7,8,9,10-octahydro-1,10-phenanthrolines and their thiono- and selenocarbonyl analogues by inclusion complexation with chiral diols
PublikacjaX-ray crystallographic analysis of the title compounds revealed that they assume a folded helical con- formation of an approximate C2 symmetry in the solid state. Dithioamide, diselenoamide and monoselenoamide were resolved to enantiomers by inclusion crystallization with optically active diols (TADDOLs). The absolute configuration of the guest molecules in the complexes was assigned as P. The optical activity of the resolved compounds...
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Polyarmonic model of synchronous generator for analysis of autonomous power generation systems
PublikacjaAbstract: This paper presents the polyharmonic modelling of synchronous generator (SG) in machine variables. The simple geometry and windings physical layout has been used for inductance calculations of a salient-pole SG. The main advantage of this model is the ease of describing an autonomous power generation system (APGS) in terms of its topology and thus providing effective analysis at the static and dynamic states, both for...
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Export Diversification and Development - Empirical Assessment
PublikacjaThis paper assesses the role played by country specific factors as determinants of exports' diversification process. Using a panel data-set for 60 countries and twenty years (1985-2004) we confirm that even after clearing out differences in income per capita, cross section variability in the degree of exports' diversification is significant. In general, apart from per capita income, variables influencing the size of accessible...
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Uncertainty assessment of ultimate strength of corroded stiffened plates subjected to different maintenance actions
PublikacjaThe study deals with the uncertainty assessment of different governing factors related to the ultimate strength of the corroded stiffened plates. The load-carrying capacity is predicted with the use of the nonlinear Finite Element Method. The most influencing governing factors in the non-linear FE analysis, such as material properties and initial imperfections are modeled and analysed as stochastic variables. The ultimate strength...
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Data from the Survey on Gdańsk University of Technology Graduates’ Professional Careers
PublikacjaThe dataset titled Data from the survey on Gdańsk University of Technology graduates’ professional careers includes data from a survey of Gdańsk University of Technology (Gdańsk Tech) graduates’ professional careers. The survey was conducted in 2017, two years after the respondents obtained graduate status. The research sample included 2553 respondents. The study concerned, i.a. the percentage of people working among graduates...
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Compatibilization of polymeric composition filled with ground tire rubber – short review
PublikacjaWaste rubber is recognized as valuable materials resource and searching for new recycling methods is the main activity of many research institutions and companies. At the turn of the last years only few scientific papers about foamed polymer compositions filled with ground tire rubber were published. In paper review about progress in compatibilization and foaming of polymeric compositions filled with ground tire rubber.
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A Pilot Study on Machining Difficult-to-Cut Materials with the Use of Tools Fabricated by SLS Technology
PublikacjaThe growing use of contemporary materials in various industrial sectors, such as aerospace, automotive, as well as the oil and gas industry, requires appropriate machining methods and tools. Currently, apart from the necessity to obtain high-dimensional and shape accuracy, the efficiency and economic aspects of the selected manufacturing process are equally important, especially when difficult-to-cut materials, such as hard and...
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Balance errors generated by numerical diffusion in the solution of non-linear open channel flow equations
PublikacjaThe paper concerns the untypical aspect of application of the dissipative numerical methods to solve nonlinear hyperbolic partial differential equations used in open channel hydraulics. It is shown that in some cases the numerical diffusion generated by the applied method of solution produces not only inaccurate solution but as well as a balance error. This error may occur even for an equation written in the conservative form not...
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Badanie wybranych właściwości wyłączników różnicowoprądowych typu F
PublikacjaW instalacjach elektrycznych niskiego napięcia instaluje się coraz więcej przekształtników energoelektronicznych (systemy fotowoltaiczne, instalacje ładowania pojazdów elektrycznych, układy napędowe o regulowanej prędkości obrotowej silnika), a mają one wpływ na dobór typu wyzwalania wyłączników różnicowoprądowych (AC, A, F lub B). W obwodach, w których pojawia się prąd różnicowy zawierający składowe o częstotliwości innej niż...
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SPECTRAL RESPONSE OF STATIONARY JACK-UP PLATFORMS LOADED BY SEA WAVES AND WIND USING PERTURBATION METHOD
PublikacjaThe paper addresses non-linear vibrations of offshore jack-up drilling platforms loaded by sea waves and wind in their stationary condition using the perturbation method. Non-linearity of dynamic equations of motion for fixed offshore platforms yields from two factors. The first is load excitation generating non-linear velocity coupling in a dynamic system. This coupling is inherent in the modified Morison equation, involving the...
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E-Learning Service Management System For Migration Towards Future Internet Architectures
PublikacjaAs access to knowledge and continuous learning are among the most valuable assets in modern, technological society, it is hardly surprising that e-learning solutions can be counted amongst the most important groups of services being deployed in modern network systems. Based on analysis of their current state-of-the-art, we decided to concentrate our research and development work on designing and implementing a management system...
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A New Method of Noncausal Identification of Time-varying Systems
PublikacjaThe paper shows that the problem of noncausal identification of a time-varying FIR (finite impulse response) sys- tem can be reformulated, and solved, as a problem of smoothing of the preestimated parameter trajectories. Characteristics of the smoothing filter should be chosen so as to provide the best trade- off between the bias and variance of the resulting estimates. It is shown that optimization of the smoothing operation can...
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SLIDING MODE-PID FUZZY CONTROLLER WITH A NEW REACHING MODE FOR UNDERWATER ROBOTIC MANIPULATORS
PublikacjaDesign of an accurate and robust controller is a challenging topic in an underwater manipulator control. This is due to hydrodynamic disturbances in underwater environment. In this paper a sliding mode control (SMC) included a PID sliding surface and fuzzy tunable gain is designed. In this proposed controller robustness property of SMC and fast response of PID are incorporated with fuzzy rules to reduce error tracking. In the...
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Electroelastic biaxial compression of nanoplates considering piezoelectric effects
PublikacjaIn the present theoretical work, it is assumed that a piezoelectric nanoplate is connected to the voltage meter which voltages have resulted from deformation of the plate due to in-plane compressive forces whether they are critical buckling loads or arbitrary forces. In order to derive governing equations, a simplified four-variable shear deformation plate theory has been employed using Hamilton’s principle and Von-Kármán...
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Application of electrochemical impedance spectroscopy to monitoring discharging process of nickel/metal hydride battery.
PublikacjaThis paper presents the possibility of applying impedance analysis to cell diagnostics. In order to obtain characteristic curves of both electrodes of a NiMH battery simultaneously, a reference electrode was added into the circuit. The authors analysed the cell under three cases, i.e. when its properties are determined only by the state of the positive electrode, only by the state of the negative electrode, or when both electrodes...
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Structural Heterogeneity Between EU15 and 12 New EU Members – the Obstacle to Lisbon Strategy Implementation
PublikacjaThe aim of this article is to identify diversity between the EU-15 and the New Members in their implementation of the Lisbon Strategy in the period 2000-2010. By analyzing a set of structural indicators, we aim to fill a gap in the literature: a lack of publications providing complex evaluation of the implementation of the Lisbon Strategy using measurable indicators. Given their suitability for international comparisons, we use...
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On structural physical approximations and entanglement breaking maps
PublikacjaVery recently, a conjecture saying that the so-called structural physical approximations (SPAs) to optimal positive maps (optimal entanglement witnesses) give entanglement breaking (EB) maps (separable states) has been posed (Korbicz et al 2008 Phys. Rev. A 78 062105). The main purpose of this contribution is to explore this subject. First, we extend the set of entanglement witnesses supporting the conjecture. Then, we ask whether...
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Some aspects of noise generated by a small ship in the shallow sea
PublikacjaThe passing and underwater moving objects produce the noises of variable intensity, which significantly increase the overall level of noise in the sea. This applies to both the sonic and ultrasonic range. The excessive levels of underwater noise adversely affects the so-called underwater acoustic climate and is the reason why this phenomenon is intensively investigated from the number of years. The results of experimental work...
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Debonding Detection in Reinforced Concrete Beams with the Use of Guided Wave Propagation
PublikacjaOne of the most frequent damage of the reinforced concrete structures is debonding between steel bar and concrete cover. In the case of debonding occurrence not only the strength of the structure decreases, but also it is more vulnerable to corrosion damages. For this reason fast and effective methods of debonding detection in an early stage of its development need a significant boost. The paper presents analytical and experimental...
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Nonlinear planar modeling of massive taut strings travelled by a force-driven point-mass
PublikacjaThe planar response of horizontal massive taut strings, travelled by a heavy point-mass, either driven by an assigned force, or moving with an assigned law, is studied. A kinematically exact model is derived for the free boundary problem via a variational approach, accounting for the singularity in the slope of the deflected string. Reactive forces exchanged between the point-mass and the string are taken into account via Lagrange...
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Effects of Surface Energy and Surface Residual Stresses on Vibro-Thermal Analysis of Chiral, Zigzag, and Armchair Types of SWCNTs Using Refined Beam Theory
PublikacjaIn this article, vibration characteristics of three different types of Single-Walled Carbon Nanotubes (SWCNTs) such as armchair, chiral, and zigzag carbon nanotubes have been investigated considering the effects of surface energy and surface residual stresses. The nanotubes are embedded in the elastic substrate of the Winkler type and are also exposed to low and high-temperature environments. A new refined beam theory namely, one-variable...
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Guided ultrasonic waves for detection of debonding in bars partially embedded in grout
PublikacjaThis paper deals with theoretical, numerical and experimental investigations of guided wave propagation in multilayered cylindrical bars with pre-existing debonding. The research focuses on a complex description of the nature of the wave phenomena occurring in a debonded specimen with a special emphasis on the influence of the location of damage on the wave conversion and diffraction. Experimental non-destructive and destructive...
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Pareto Ranking Bisection Algorithm for EM-Driven Multi-Objective Design of Antennas in Highly-Dimensional Parameter Spaces
PublikacjaA deterministic technique for fast surrogate-assisted multi-objective design optimization of antennas in highly-dimensional parameters spaces has been discussed. In this two-stage approach, the initial approximation of the Pareto set representing the best compromise between conflicting objectives is obtained using a bisection algorithm which finds new Pareto-optimal designs by dividing the line segments interconnecting previously...
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Wild oscillations in a nonlinear neuron model with resets: (I) Bursting, spike-adding and chaos
PublikacjaIn a series of two papers, we investigate the mechanisms by which complex oscillations are generated in a class of nonlinear dynamical systems with resets modeling the voltage and adaptation of neurons. This first paper presents mathematical analysis showing that the system can support bursts of any period as a function of model parameters, and that these are organized in a period-incrementing structure. In continuous dynamical...
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Radio Channel Measurements in 868 MHz Off-Body Communications in a Ferry Environment
PublikacjaIn this paper, a characterization of the 868 MHz off-body radio channel in BANs is presented. Measurements were carried out in a ferry environment using a specific set-up. A method for path loss using radio distance measurements (RDMs) was developed. It allows to automate the measurements process and make it independent from the variable speed of a moving person. Based on the observed path loss as a function of distance, the obtained...
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Local electrochemical impedance spectroscopy in dynamic mode of galvanic coupling
PublikacjaA novel method that combines local electrochemical impedance spectroscopy and mapping in dynamicmode is proposed. Method was validated over two galvanic couplings, namely zinc/copper and cad-mium/copper. Impedance spectrum response for all measuring points was obtained by means ofsimultaneous implementation of selected range of frequencies. Proposed method allows the measure-ment in a more time-efficient manner, at the same time...
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Specificity of Infant Digestive Conditions: Some Clues for Developing Relevant In Vitro Models
PublikacjaDigestion of nutrients is an essential function of the newborn infant gut to allow growth and development and understanding infant digestive function is essential to optimize nutrition and oral drug delivery. Ethical considerations prohibit invasive in vivo trials and as a consequence in vitro assays are often conducted. However, the choice of in vitro model parameters are not supported by an exhaustive analysis of the literature...
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Assessing groundwater vulnerability to pollution in the Puck region (denudation moraine upland) using vertical seepage method
PublikacjaDegradation of groundwater quality can cause a serious water supply and environmental problems. The identify of potential groundwater pollution can be determined by assessment of groundwater vulnerability method. The assessment of groundwater vulnerability to pollution was based on estimation of migration time of potential conservative contamination through the vadose zone. Area of investigation is a type of denudation moraine...
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Nanoindentation tests titanium alloy Ti-6Al-4V after interference laser treatment
PublikacjaThe study aimed was to assess selected mechanical properties of surface layers obtained after interference laser treatment – DLIL of titanium alloy Ti-6Al-4V used for implants. The samples were melted in still air at room temperature, for this purpose Nd:YAG laser was used, the number of laser shots was variable. Next, nanoindentation tests were performed, based on which Young’s modulus and nanohardness in the obtained surface...