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Measurements of Thermal Conductivity of LWC Cement Composites Using Simplified Laboratory Scale Method
PublicationThe implementation of low-energy construction includes aspects related to technological and material research regarding thermal insulation. New solutions are sought, firstly, to reduce heat losses and, secondly, to improve the environment conditions in isolated rooms. The effective heat resistance of insulating materials is inversely proportional to temperature and humidity. Cement composites filled with lightweight artificial...
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Charge Transport in High-Entropy Oxides
PublicationThis work presents the results of research on the transport properties of the high-entropy BaZr1/8Hf1/8Sn1/8Ti1/8Y1/8In1/8Sm1/8Yb1/8O3–x perovskite oxide with special focus on proton transport. The presented study is part of broader work in which we focus on multiple different chemical compositions with the cation number varying from 5 up to 12 (in B-sublattice). The presence of proton defects is analyzed with thermogravimetry,...
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Analytical approach for membrane action in laterally-restrained reinforced concrete square slabs under uniformly distributed loads
PublicationLaterally-restrained reinforced concrete slabs can mobilise compressive membrane action and subsequent tensile membrane action under extreme loading conditions, thereby enhancing the load resistance under uniformly distributed loads. Previous analytical study focuses primarily on tensile membrane action in simply-supported slabs. This paper describes an analytical approach for membrane action in laterally-restrained square slabs....
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CHARAKTERYSTYKA WYMIANY CIEPŁA I OPORÓW PRZEPŁYWU OMYWANIA MIKROSTRUGAMI ROZWINIĘTEJ POWIERZCHNI
PublicationW artykule przedstawiono eksperymentalne badania kompaktowego wymiennika ciepła z intensyfikacją przejmowania ciepła przy użyciu mikrostrug. Niniejszy artykuł przedstawia projekt i testy prototypu, wymiennika ciepła typu mikrostrugowego. Modułowa konstrukcja wymiennika umożliwia zmianę wymiarów geometrycznych, a także zmianę materiału przegrody wymiennika ciepła. Metoda graficzna Wilsona została z zastosowana w celu określenia...
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Microstructure and residual stresses in surface coatings with PTFE reservoirs
PublicationThe paper presents the results of experimental study into the microstructure and changes in residual stresses resulting from sliding and rolling/sliding loaded interaction between metallic surface coatings with embedded PTFE reservoirs and various counter faces. It was found that before testing surface coatings had compressive residual stresses. Molybdenum coating with all types of PTFE reservoirs displayed, as a result of testing,...
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A method to synthesise groove cam Geneva mechanisms with increased dwell period
PublicationThe present study develops a method to synthesise the groove cam Geneva mechanism with increased dwell period. The main condition of the synthesis is to provide the desired law of motion of the wheel. Additional synthesis conditions are the limitation of the maximum pressure angle and the limitation of the minimum curvature radius of the cam profile. Unlike the conventional Geneva mechanisms, the synthesised groove cam Geneva mechanisms...
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Numerical simulation of natural convection of Glycol-Al2O3 nanofluids from a horizontal cylinder
PublicationThis paper deals with natural convection around a circular cylinder with constant heat flux in a cavity using computational fluid dynamics. As fluids ethylene glycol and a mixture of ethylene glycol with Al2O3 nanoparticles (mass concentrations of nanoparticles: 0.1% and 1%) are chosen. Rayleigh number ranges from 3104 to 3105. The nanofluids are modeled with single-phase approach. For the investigated range of nanoparticle concentration, the...
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A Comparison of STI Measured by Direct and Indirect Methods for Interiors Coupled with Sound Reinforcement Systems
PublicationThis paper presents a comparison of STI (Speech Transmission Index) coefficient measurement results carried out by direct and indirect methods. First, acoustic parameters important in the context of public address and sound reinforcement systems are recalled. A measurement methodology is presented that employs various test signals to determine impulse responses. The process of evaluating sound system performance, signals enabling...
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Experimental investigation of two-phase thermosyphon heat exchanger charged with acetone
PublicationThis paper presents thermal characteristics of prototype of a two-phase thermosyphon heat exchanger (TPTHEx) charged with acetone as a working fluid. The TPTHEx consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. The tested TPTHEx operates in a vacuum. Therefore, the working liquid is boiled...
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Detection of Polish clinical Aspergillus fumigatus isolates resistant to triazoles
PublicationWe studied the presence of triazole resistance of 121 Aspergillus fumigatus clinical isolates collected in two Polish cities, Warsaw and Wrocław, to determine if resistance is emerging in our country. We identified five itraconazole resistant isolates (4.13%) carrying the TR34/L98H alteration in Cyp51A gene, four of which were cross-resistant to posaconazole and one to voriconazole. One isolate was intermediate susceptible to itraconazole...
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Charakterystyka oporności Klebsiella pneumoniae New Delhi na karbapenemy
PublicationBakterie Klebsiella pneumoniae New Delhi, posiadające gen oporności na karbapenemy (blaNDM) zostały po raz pierwszy wyizolowane w 2008 roku w Szwecji od pacjenta wcześniej hospitalizowanego w Indiach. Bakterie te szybko rozprzestrzeniają się po całym świecie, a od 2011 roku występują również w Polsce. Stanowią one wysokie ryzyko epidemiologiczne, ponieważ gen oporności na karbapenemy przekazywany jest pomiędzy bakteriami poprzez...
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Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy
PublicationIn this article, the mechanical properties and microstructure of 304L austenitic stainless steel/Incoloy 800HT nickel alloy dissimilar welded joints are investigated. The joints were made of 21.3 mm × 7.47 mm tubes using the TIG process with the use of S Ni 6082 nickel filler metal. No welding imperfections were found and high strength properties of joints were obtained, meeting the assumed acceptance criteria of the product’s...
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Underwater Electrochemical Offshore Tests of a Paint Coating Applied in Water on the Legs of an Oil Production Platform
PublicationThis paper presents the methodology developed for underwater measurements using electrochemical impedance spectroscopy (EIS) technique, aimed at determining the resistance of an epoxy coating applied in seawater to the legs of an oil production platform. Performing such underwater tests in an offshore environment was technically challenging. The results of measurements obtained on the platform were confronted with comparative results...
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Comparative study of flow condensation in conventional and small diameter tubes
PublicationIn the paper a method developed earlier by the first author is applied to calculations of heat transfer coefficient for inside tube condensation. The method has been verified using experimental data from literature on several fluids in different microchannels and compared to three well established correlations.
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Analysis of positioning methods using Global Navigation Satellite Systems (GNSS) in Polish State Railways (PKP)
PublicationEach year, global navigation satellite systems (GNSS) improve their accuracy, availability, continuity, integrity, and reliability. Due to these continual improvements, the systems are increasingly used in various modes of transport, including rail transport, the subject of this publication. GNSS are used for rail passenger information, rail traffic management, and rail traffic control. These applications differ in the positioning...
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Współczynniki strat energetycznych w elementach napędu hydrostatycznego
PublicationW każdym układzie napędowym należy zastąpić obraz przepływu mocy opisany dotychczas powszechnie stosowanym wykresem Sankey’a spadku mocy zgodnego z kierunkiem przepływu mocy proponowanym przez autora wykresem wzrostu mocy w układzie przeciwnego do kierunku przepływu mocy. Należy więc opisywać straty i sprawność energetyczną a także pole pracy każdego silnika i układu napędowego jako zależne od wielkości fizycznych niezależnych...
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Drug-resistant and hospital-associated Enterococcus faecium from wastewater, riverine estuary and anthropogenically impacted marine catchment basin.
PublicationEnterococci, ubiquitous colonizers of humans and other animals, play an increasingly important role in health-care associated infections (HAIs). Acquisition of resistance determinants not only seriously limits available therapeutic options but also increases available gene pool for other species. It is believed that the recent evolution of two clinically relevant species, Enterococcus faecalis and Enterococcus faecium occurred...
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Nickel-nanodiamond coatings electrodeposited from tartrate electrolyte at ambient temperature
PublicationIn this study, nanocrystalline Ni and Ni-diamond coatings were obtained by electrodeposition from tartrate electrolyte at ambient temperature aiming at improving corrosion and wear properties of the material. The created surfaces were investigated with regard to microhardness, adhesion, wear- and corrosion-resistance. The various methods such as atomic force microscopy, scanning electron microscopy, electrochemical impedance spectroscopy...
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Hydrogen Damage in Superaustenitic 904L Stainless Steels
Publicationresults on the influence of hydrogen on corrosion resistance and of hydrogen embrittlement of 904L superaustenitic stainless steel were investigated. The cracking behavior was studied by performing a slow strain rate test in synthetic seawater under varying cathodic polarization conditions. The results showed that the steel’s plasticity varied with the applied cathodic current density. Significant reductions in ductility were found,...
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Effect of cobalt addition on the corrosion behaviorof near equiatomic NiTi shape memory alloy in normal saline solution: electrochemical and XPS studies
PublicationThe electrochemical and corrosion (uniform and localized) behavior of a binary Ni52Ti48 shape memory alloy (SMA) and two ternary Ni52Ti48-xCox (x = 1.5 and 4.0 wt.%) SMAs were studied. Measurements were conducted in 0.9% NaCl solution at 37 oC employing various electrochemical methods. These include: linear polarization resistance (LPR), linear sweep voltammetry (LSV), chronoamperometry and dynamic electrochemical impedance spectroscopy...
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Generalized Dobrushin Coefficients on Banach Spaces
PublicationThe asymptotic behavior of iterates of bounded linear operators (not necessarily positive), acting on Banach spaces, is studied. Through the Dobrushin ergodicity coefficient, we generalize some ergodic theorems obtained earlier for classical Markov semigroups acting on L1 (or positive operators on abstract state spaces).
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Structure and thermoelectric properties of Te/Ag/Ge/Sb (TAGS) materials obtained by reduction of melted oxide substrates
PublicationThe Ge0.77Ag0.1Sb0.13Te1alloy was fabricated by a novel two step route. For that purpose firstly the oxide reagents were melted at high temperature and quenched into pellets. After that pellets were milled to the powder and then reduced in hydrogen at various temperatures and for various periods of time. Energy dispersive X-ray analysis indicated the possibility of successful fabrication of stoichiometric thermoelectric materials...
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Slurry Erosion -Design of Test Devices
PublicationDegradation of material caused by impacts of a solid particle (erodent) suspended in a liquid is called slurry erosion and is a major problem in the hydropower and maritime industry. Slurry erosion depends on many factors, e.g. liquid and erodent velocity, size, shape, angle of impact, hardness and number of erodents, and strength of a target material. The various types of test devices have been designed to investigate an effect...
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Mechanical Properties of a Dike Formed from a Soil-ash Composite
PublicationThe paper presents the research results on application of composite soils for dike construction. The composite soil is produced by mixing bottom ash (by-product of energetics) with dredged material (sand) taken from the mouth of The Vistula river. The optimum composite for dike core was chosen with respect to mechanical parameters: high internal friction angle, good compaction and reduced hydraulic conductivity. The test dike was...
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Degradation of protective coatings in steel chimneys of flue gas desulfurisation system
PublicationThis paper presents problems associated with corrosion of steel stacks and changes in philosophy of corrosion protection when implemented into flue gas desulphurization systems. In-situ tests were taken by means of electrochemical impedance spectroscopy at the stack which discharges flue gas before wet lime/limestone desulphurization. A very quick electrolyte absorption by the spherical infill vinylester coating was found using...
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Discrimination of hospital isolates of Acinetobacter baumannii using repeated sequences and whole genome alignment differential analysis
PublicationAn optimized method for bacterial strain differentiation, based on combination of Repeated Sequences and Whole Genome Alignment Differential Analysis (RS&WGADA), is presented in this report. In this analysis, 51 Acinetobacter baumannii multidrug-resistance strains from one hospital environment and patients from 14 hospital wards were classified on the basis of polymorphisms of repeated sequences located in CRISPR region, variation...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: a review
PublicationPurpose – This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors. Design/methodology/approach – This paper compares various methods of improving gas sensing by temperature modulation, UV irradiation or fluctuation-enhanced sensing. The authors analyze low-frequency resistance fluctuations in commercial Taguchi gas sensors and the recently developed tungsten trioxide (WO3) gas-sensing...
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CO2 capture using steam ejector condenser under electro hydrodynamic actuator with non-condensable gas and cyclone separator: A numerical study
PublicationThe concept for condensation of steam and CO2 separation in a negative CO2 emission gas power plant involves the utilization of a steam ejector condenser (SEC) for direct-contact condensation of vapor with inert gas (CO2) on a spray of subcooled liquid, integrated with a separator to produce pure CO2. Due to the increasing diffusion resistance and reduced convective heat transfer between the steam and subcooled water phases...
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Analytical ‘Steady-State’-Based Derivation and Clarification of the Courant-Friedrichs-Lewy Condition for Pipe Flow
PublicationThis article addresses the problem of choosing the optimal discretization grid for emulating fluid flow through a pipeline. The aggregated basic flow model is linearized near the operating point obtained from the steady state analytic solution of the differential equations under consideration. Based on this model, the relationship between the Courant number (μ) and the stability margin is examined. The numerically set coefficient...
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Contribution of dynamic vehicle loads to pavement failure
PublicationPavement surfaces are not ideally even, which causes dynamic loads of vehicle axles. Distribution of dynamic loads of a given axle is similar to normal distribution and can be described by static load and dynamic load coefficient. The dynamic load coefficient depends on road profile, vehicle speed, properties of suspensions and static load of axle. While for a given road section road profile remains constant, vehicle speed and...
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Electrical mapping of AISI 304 stainless steel subjected to intergranular corrosion performed by means of AFM-LIS in the contact mode
PublicationThe paper presents results of the AFM-based approach to local impedance spectroscopy (LIS) measurements performed in a 20 20 lm grid within an austenite grain–grain boundary region for sensitized AISI 304 stainless steel (SS). Maps of electrical parameters obtained on the basis of localized impedance spectra were demonstrated, presenting their changes and correlation with the sample topography. Performed research revealed significant...
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Mechanical and thermo-mechanical properties of natural rubber composites filled with submicron- and nano-sized silica particles and prepared using glycolysate as a plasticizer
PublicationThe main aim of this work was to examine the selected mechanical and thermo-mechanical properties of natural rubber/silica composites prepared using glycolysate as a plasticizer. Prepared composites contained different amounts of submicron- (10, 15, 20 or 25 pphr) or nano-particles (0.5, 0.75, 1.0 or 1.25 pphr). The tensile properties, tear resistance, hardness, abrasion resistance and resilience of prepared materials were determined....
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Fluctuation-enhanced scent sensing using a single gas sensor
PublicationScent or aroma sensing during aromatherapy can be carried out by applying only a single resistance gas sensor (TGS - Taguchi Gas Sensors). This paper considers the efficiency of detection of essential oils by DC resistance and its fluctuations observed in TGS sensors. A detailed study has been conducted for scents emitted by five popular essential oils using three sensor types (TGS 2600, TGS 2602, TGS 823). The research was focused...
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Drgania i hałaśliwość silników asynchronicznych - weryfikacja nowych hipotez
PublicationArtykuł zawiera nowe spojrzenie na postaci drgań kadłuba i tarcz silników asynchronicznych wymuszanych siłami elektromagnetycznymi. Omówiono badania postaci drgań własnych i eksploatacyjnych kadłuba i tarcz łożyskowych. Poddano analizie związki przyczynowo-skutkowe postaci drgań tarcz łożyskowych z łożyskami tocznymi i ślizgowymi. Wykazano, że wibracyjne eksploatacyjne odkształcenia tarcz silników klatkowych małej i średniej mocy,...
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Analiza porównawcza metod zwiększania nośności i sztywności stalowych, doczołowych węzłów śrubowych.
PublicationInnowacyjna, w porównaniu z dotychczas stosowanym sposobem, metoda obliczania nośności stalowych węzłów została wdrożona wraz z normami europejskimi. Pozwala ona dokładniej odwzo-rować rzeczywistą pracę poszczególnych części węzła, gdyż wynik obliczeń uzależniony jest od znacznie większej liczby zmiennych. Dzięki postępowi technologicznemu w zakresie metalurgii oraz badaniom naukowym obecnie możliwe jest wzmacnianie połączeń...
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A method of RTS noise identification in noise signals of semiconductor devices in the time domain
PublicationIn the paper a new method of Random Telegraph Signal (RTS) noise identification is presented. The method is based on a standardized histogram of instantaneous noise values and processing by Gram-Charlier series. To find a device generating RTS noise by the presented method one should count the number of significant coefficients of the Gram-Charlier series. This would allow to recognize the type of noise. There is always one (first)...
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Frequency Guided Generalized Adaptive Notch Filtering - Tracking Analysis and Optimization
PublicationGeneralized adaptive notch filters (GANFs) are estimators of coefficients of quasi-periodically time-varying systems, encountered e.g., in RF applications when Doppler effect takes place. Current state of the art GANFs can deliver highly accurate estimates of system variations’ frequency, but underperform in terms of accuracy of system coefficient estimates. The paper proposes a novel multistage GANF with improved coefficient...
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Thermal performance of a prototype plate heat exchanger with minichannels under boiling conditions
PublicationTo solve the problem and to meet the requirements of customers in the field of high heat fluxes transfer in compact units, a new design of plate heat exchanger with minichannels (minichannels PHE) was proposed. The aim was to construct a compact heat exchanger of high effectiveness for the purpose of household cogeneration ORC system. In this paper the experimental analysis of an assembled prototype of such compact heat exchanger...
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Friction and Lubrication of Large Tilting-Pad Thrust Bearings
PublicationFluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due...
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A Meta-Analysis of Pulse Arrival Time Based Blood Pressure Estimation
PublicationThe paper presents a preliminary meta-analysis of the sample correlation between pulse arrival time (PAT) and blood pressure (BP). The aim of the study was to verify sample correlation coefficient between PAT and BP using an affine model BP = a · P AT + b for systolic and diastolic blood pressure. The databases included in the search were the IEEE Xplore Digital Library, Springer Link and Google Scholar. Only papers from 2005 to...
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Automatic Marking of Allophone Boundaries in Isolated English spoken Words
PublicationThe work presents a method that allows delimiting the borders of allophones in isolated English words. The described method is based on the DTW algorithm combining two signals, a reference signal and an analyzed one. As the reference signal, recordings from the MODALITY database were used, from which the words were extracted. This database was also used for tests, which were described. Test results show that the automatic determination...
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Wpływ technicznych włókien celulozowych na wybrane właściwości kompozytów kauczuku naturalnego
PublicationCelem niniejszej pracy było zbadanie wpływu technicznych włókien celulozowych (dodanych w ilości 10, 20, 30 i 40 phr) jako naturalnego napełniacza na wybrane właściwości kompozytów na osnowie kauczuku naturalnego. Zbadano właściwości wulkanizatów przy statycznym rozciąganiu, w próbie rozdzierności, a także twardość, elastyczność przy odbiciu oraz ścieralność otrzymanych materiałów. Wyniki badań zostały porównane z wulkanizatem...
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Estimation of the effectiveness of nbpt for limiting ammonia emission from urea based on the field experiments
PublicationThe efectiveness of the ammonia emission reduction from NBPT-stabilized urea was investigating in 2011 during a field experiment on a grassland plot fertilized with a one-time dose of 60 kgN/ha. The obtained reduction coefficient of ammonia emission equaled 73% and 39-51% relative to erea without the inhibitor and ammonium nitrate, respectively.
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Prediction of Pile Shaft Capacity in Tension Based on Some Direct CPT Methods—Vistula Marshland Test Site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with diameter 0.4 m and the length varied from 8 m to 14.6 m were subjected to static load tests in tension. Their...
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Influence of the thermal modernization of window on transmission heat losses
PublicationThe article presents the results of calculations of the heat transfer coefficient for the state before and after renovation for the historic windows. The aim of the analysis was to obtain the values of thermal insulation parameters demanded by the regulations, while not losing the historical value of the window. The described example of the renovation of the existing window consisted in installing an additional window panel from...
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Impedance of cation-coupled electron transfer reaction: Theoretical description of one pathway process
PublicationIt has been assumed that cation electron coupled charge transfer can be conducted in accordance with two mutually coupled reactions. Using a differential method an expression was introduced which describes the impedance of a cation electron coupled transfer reaction. Also, an electrical equivalent circuit has been defined. The total faradaic impedance is the sum of electron transfer impedance and cation transfer impedance. Issues...
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The mechanism of grouting action under the base of bored pile
PublicationThe grouting under the base of bored pile is carried out in order to reduce pile settlement and improve its bearing capacity. The principal aim of grouting is to introduce an initial force between the soil and the pile base. In non-cohesive soil, the grouting can also enlarge the pile base area and therefore improve the base resistance. The example of static load tests on instrumented bored piles installed with and without grouting...
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Influence of laser melting on surface layer properties of titanium alloy Ti6Al4V
PublicationIn time of rapid technology and medicine progress, implants are becoming more widely used in the human body, ranging from dental implants, stabilizing plates, screws, orthopaedic prostheses. For example, there are many types of hip prostheses used for hip replacement as well as various types of materials used for these orthopaedic prostheses. Properties of titanium alloys used in hip prostheses combined with good strength properties,...
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Morphology of bio-based polyurethane composites filled by mer-cerized or silanized natural fibres
PublicationBio-composites are materials which possess unique properties and undergo biodegra-dation under specific conditions. Bio-composites belong to the group of materials produced with the use of renewable raw materials. They contain reinforcement, mainly in the form of natural fiber, which has high stiffness and resistance; filler powders are less frequently used. Significant features of natural fibers are elongation, density, thermal...
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The Impact of Crushed Rock Spoil on Pitting Corrosion of Selected Stainless Steel
PublicationThe paper presents the results of the pitting resistance investigations of selected stainless steels in the chloride environment and the simultaneous impact of erosive factors using the cyclic polarization technique. Additionally, using electrochemical techniques, ie: electrochemical impedance spectroscopy (EIS) and measurement of corrosion potential, the behavior of the passive layer of selected stainless steels in the environment...