Nowe zasoby w Repozytorium PK http://suw.biblos.pk.edu.pl/ Biblioteka Politechniki Krakowskiej lipinska@biblos.pk.edu.pl 60 <![CDATA[Dynamic simulations for inhomogeneous components]]> Tue, 07 Apr 2020 11:50:31 +0200 Baldinelli, Giorgio; Bianchi, Francesco; Lechowska, Agnieszka; Schnotale, Jacek
rodzaj: materiały konferencyjne w książce
Abstrakt: For highly inhomogeneous components (windows, doors, etc...), imposing sinusoidal temperatures from one side and constant temperature to the other side, could give periodic thermal transmittance exactly with the same definition described in the standard EN 13786. For thermal bridges something similar to the ψ value of steady-state conditions could be defined: the idea is that a homogenous wall as its own periodic thermal transmittance; when a thermal bridge is applied to this wall (for instance with the insertion of a pillar), the simulation will give a new periodic thermal transmittance. The difference between the two periodic thermal transmittances gives information on the effect of the thermal bridge, obtaining something similar to the ψ value. With a Computational Fluid Dynamic analysis, the paper deals with the definition of linear periodic thermal transmittance that could be useful for the response of the whole building envelope (in terms of complex heat flow rate through the inner environment) to the external temperature oscillation. This approach opens the way to define a new Standard to include thermal bridges and inhomogeneous components in general in the dynamic calculations of the buildings envelope.]]>
<![CDATA[Synthesis and performance of TiO2/fly ash cenospheres as a catalytic film in a novel type of periodic air-sparged photocatalytic reactor]]> Tue, 07 Apr 2020 09:16:06 +0200 Żukowski, Witold; Migas, Przemysław; Bradło, Dariusz; Dulian, Piotr
rodzaj: artykuł w czasopiśmie
Abstrakt: The results of a photocatalytic process performed in a new type of inclined, three-phase fluidised bed reactor with a periodic photocatalyst film are presented. These phases were fly ash cenospheres coated with TiO2, an aqueous solution of methylene blue and an air stream passing from the bottom of the photoreactor. The cenospheres have a density lower than water and could thus form a catalytic film on a top irradiated window. The formed surface film is stable but is easy to break and be reproduced in a cyclic air-sparged process. Mixing was performed in either a cyclic or a continuous manner. From an operational point of view, the best variant of mixing was a 10 s air-sparge/10 s break with a 50% duty cycle, because it provided the same discolouration efficiency and reduced energy demand by 50% in comparison with the continuous mixing. Due to film formation, the proposed catalytic reactor enables a substantial reduction in the energy required for mixing while maintaining the desired degree of discolouration.]]>
<![CDATA[An overview of potential application of acoustic emission in machining processes]]> Tue, 07 Apr 2020 07:06:08 +0200 Krajewska-Śpiewak, Joanna; Żyra, Agnieszka
rodzaj: materiały konferencyjne w książce
Abstrakt: The paper presents the potential application of acoustic emission method (AE) in conventional and unconventional machining processes. To reduce the probability of production defects more attention is paid to the manufacturing processes monitoring. According to the basis of acoustic emission method, which allows for analyzing material destruction in the entire volume of the analyzed sample in real time were described. An overview of potential application of AE method in conventional machining processes such as cutting and also during electro discharge machining were presented.]]>
<![CDATA[Use of dynamically adaptive grid techniques for the solution of electrochemical kinetic equations Part 3. An adaptive moving grid–adaptive time step strategy for problems with discontinuous boundary conditions at the electrodes]]> Mon, 06 Apr 2020 18:16:38 +0200 Bieniasz, Lesław K.
rodzaj: artykuł w czasopiśmie
Abstrakt: The finite-difference adaptive moving grid strategy suggested in Parts 1 and 2 for the solution of electrochemical kinetic one-dimensional partial differential equations has been further extended to allow temporal grid adaptation as well as time-stepping across discontinuities in boundary conditions. This extension aims at the development of a general simulation algorithm, capable of a largely automatic solution of a variety of kinetic problems. The validity of the strategy developed has been tested on three examples of the modelling of electrochemical transients: square-wave-controlled potential transient in pure diffusion conditions, potential-step transient for the catalytic electrode reaction mechanism with a fast homogeneous reaction and linear potential scan voltammetric transient for an electrode reaction accompanied by a fast follow-up homogeneous dimerization reaction.]]>
<![CDATA[Use of dynamically adaptive grid techniques for the solution of electrochemical kinetic equations Part 4: The adaptive moving-grid solution of one-dimensional fast homogeneous reaction-diffusion problems with extremely thin reaction zones away from the electrodes ]]> Mon, 06 Apr 2020 17:51:24 +0200 Bieniasz, Lesław K.
rodzaj: artykuł w czasopiśmie
Abstrakt: The adaptive moving-grid strategy suggested in Parts 1–3 for the solution of electrochemical kinetic partial differential equations in one space dimension has been subject to further evaluation and tuning. The strategy has been applied to two kinetic examples of fast homogeneous reaction–diffusion systems involving extremely thin moving reaction zones away from the electrodes. One example, the simulation of the double-potential step transient for a simple mechanism of electrogenerated chemiluminescence, has been considered in much detail. As the second example the simulation of the linear potential scan voltammetry for a double-electron transfer with "nuances" has been briefly discussed. The adaptive grid strategy provides effective, satisfactorily accurate and complete solutions to these difficult problems, which would not be possible to obtain by traditional fixed-grid finite difference methods, except at much higher computational cost or with radical simplifications.]]>
<![CDATA[Ground reaction forces generated by runners – harmonic analyses and modelling]]> Mon, 06 Apr 2020 17:37:48 +0200 Pańtak, Marek
rodzaj: artykuł w czasopiśmie
Abstrakt: Building structures carrying pedestrian traffic, e.g., footbridges, long-span floors and long cantilevered platforms projecting outwards from the walls (long balconies), can be susceptible to the dynamic influence of its users. One type of dynamic action that can occur on these structures is the dynamic action of people running. The main aim of this paper is to present the results of the harmonic analyses and mathematical models of two types of ground reaction forces (GRFs) generated by people applying different running techniques, i.e., forefoot- and heel-strike (rearfoot) running technique. The analyses of the GRFs were performed on the basis of the results of laboratory tests of running people and concern the vertical component of the ground reaction forces (VGRFs) generated by runners. The harmonic analyses were performed using Fourier transform. The results of the study show the main features and differences between forces generated by forefoot- and heel-strike runners. Data obtained for various running styles allowed the development of a load model proposal for the VGRFs generated by heel-strike runners. The results of the VGRF parameterization and the proposed new VGRF model allow the VGRFs generated by forefoot and heel-strike runners to be accurately estimated in the case of normal running pace (recreational running). The application of the presented results allows improvements to the accuracy of determining the dynamic response of structures induced by runners.]]>
<![CDATA[Sensitivity of mountain catchments to global warming: a case study of the San Basin, Poland]]> Mon, 06 Apr 2020 17:35:54 +0200 Kędra, Mariola
rodzaj: artykuł w czasopiśmie
Abstrakt: In changing climatic conditions with rising surface air temperatures mountain regions with their characteristic environment and accumulated snow deserve special attention and sustainable management. To investigate the sensitivity of mountain catchments to global warming, this study explores potential trends for hydro-climatic variables between 1957 and 2016 (60 years). Based on the Mann-Kendall test results, upward trends in air temperature were found from April to August; they are accompanied by less frequent but significant trends in precipitation, with increases in precipitation for January and May, but a decrease for December. For river flow, significant upward trends were identified only for January, in line with precipitation trends. In addition, comparative analyzes of changes for two 30-year periods (1987–2016 versus 1957–1986) corroborate the main change directions and provide detailed information for more realistic future land and water management in the mountain catchments studied.]]>
<![CDATA[Detection and monitoring of bottom-up cracks in road pavement using a machine-learning approach]]> Mon, 06 Apr 2020 17:34:44 +0200 Praticò, Filippo Giammaria; Fedele, Rosario; Naumov, Vitalii; Sauer, Tomas
rodzaj: artykuł w czasopiśmie
Abstrakt: The current methods that aim at monitoring the structural health status (SHS) of road pavements allow detecting surface defects and failures. This notwithstanding, there is a lack of methods and systems that are able to identify concealed cracks (particularly, bottom-up cracks) and monitor their growth over time. For this reason, the objective of this study is to set up a supervised machine learning (ML)-based method for the identification and classification of the SHS of a differently cracked road pavement based on its vibro-acoustic signature. The method aims at collecting these signatures (using acoustic-sensors, located at the roadside) and classifying the pavement’s SHS through ML models. Different ML classifiers (i.e., multilayer perceptron, MLP, convolutional neural network, CNN, random forest classifier, RFC, and support vector classifier, SVC) were used and compared. Results show the possibility of associating with great accuracy (i.e., MLP = 91.8%, CNN = 95.6%, RFC = 91.0%, and SVC = 99.1%) a specific vibro-acoustic signature to a differently cracked road pavement. These results are encouraging and represent the bases for the application of the proposed method in real contexts, such as monitoring roads and bridges using wireless sensor networks, which is the target of future studies.]]>
<![CDATA[Gra brył domu jednorodzinnego]]> Mon, 06 Apr 2020 11:38:27 +0200 Kozłowski, Tomasz
rodzaj: artykuł w czasopiśmie
Abstrakt: Świat architektury zmienia się, jest to dość oczywiste. Piękno tak potrzebne kiedyś jako warunek sine qua non istnienia działa sztuki umarło. Funkcja budująca przez ostatnie dekady kształt architektury jest dziś raczej błahym pretekstem. Kompozycja niezbędna w tworzeniu sztuki została zabita przez sztukę awangardową. Sztuka dekompozycji wdarła się natarczywie w świat architektury. Dom jednorodzinny, do którego się przyzwyczailiśmy także zmianie swój kształt. Duch ekspresjonizmu wdziera się do architektury mieszkaniowej. Nauka projektowania musi podążyć nową, nie do końca znaną drogą.]]>
<![CDATA[Monte Carlo-based procedure for determining the maximum energy at the output of accelerometers]]> Mon, 06 Apr 2020 11:35:52 +0200 Tomczyk, Krzysztof
rodzaj: artykuł w czasopiśmie
Abstrakt: The solutions presented in this paper can be the basis for mutual comparison of different types of accelerometers produced by competing companies. An application of a procedure based on the Monte Carlo method to determine the maximum energy at the output of accelerometers is discussed here. The fixed-point algorithm controlled by the Monte Carlo method is used to determine this energy. This algorithm can only be used for the time-invariant and linear measurement systems. Hence, the accelerometer nonlinearities are not considered here. The mathematical models of the accelerometer and the special filter, represented by the relevant transfer functions, are the basis for the above procedure. Testing results of the voltage-mode accelerometer of type DJB A/1800/V are presented here as an example of an implementation of the solutions proposed. Calculation of the energy was executed in Mathcad 14 program with the built-in Programming Toolbar. The value of the maximum output energy determined for a specified time interval corresponds to the maximum integral-square error of the accelerometer. Such maximum energy can be a comparative ratio just like the accuracy class in the case of instruments used for the static measurements. Hence, the main analytical and technical contributions of this paper concern the development of theoretical procedures and the presentation of their application on the example of a real type of accelerometer.]]>
<![CDATA[Sustainable suburban supply chain]]> Mon, 06 Apr 2020 10:58:09 +0200 Rossolov, Alexander; Lobashov, Oleksii; Kopytkov, Denis; Naumov, Vitalii
rodzaj: materiały konferencyjne w czasopiśmie
Abstrakt: The paper deals with the issue of building a suburban supply chain from the standpoint of sustainable development. Mathematical models for determining the rational number of local depots have been obtained taking into account the amount of CO2 emissions and the monetary assessment of the negative environmental impact of the suburban supply chain. The study considers the variable nature of the demand for the supply of the goods by estimating the changes in the number of customers at the service area and each customer delivery size. The theory of planning extreme experiments has been used to describe the possible states of the usual and sustainable suburban supply chain option. Experimental studies of the supply chain functioning in two options have been conducted for alternative vehicles with a load-carrying capacity of 0.6 to 2.0 tons. As a result, a rational number of the local depots has been determined for the usual and sustainable option of the suburban supply chain.]]>
<![CDATA[Development of adaptive methods for reaction-diffusion and other transport problems arising in electrochemistry]]> Mon, 06 Apr 2020 08:51:57 +0200 Bieniasz, Lesław K.
rodzaj: materiały konferencyjne w czasopiśmie
Abstrakt: In the course of over 15 years of work of the author, on the development of adaptive finite-difference methods for reaction-diffusion and other reactive transport phenomena occurring in electrochemistry, much experience has been accumulated, which can also be of interest to modellers in other areas, including materials science. The results of that research are briefly summarized, indicating the advantages and disadvantages of the various methods. It is argued that much more work still has to be done to design satisfactory adaptive methods, even for spatially one-dimensional equations, despite the fact that for such problems the adaptive methodology is currently regarded to be mature.]]>
<![CDATA[Identyfikacja i implementacja wzorców prawidłowego kształtowania śródmiejskiej ulicy na przykładzie miasta Rzeszowa : rozprawa doktorska]]> Fri, 03 Apr 2020 17:35:18 +0200 Dudek, Joanna
rodzaj: rozprawa doktorska
Abstrakt: Jedna spośród wielu definicji miasta określa tę strukturę osadniczą jako miejsce spotkań, handlu i komunikacji. Wymienione w przytoczonym sformułowaniu czynniki miastotwórcze to trzy odmienne rodzaje aktywności. Każda spośród nich wymaga infrastruktury odpowiedniej do swojej specyfiki. Miasta na różnych etapach rozwoju dostosowywały swoją tkankę do tych aktywności, których obecność była im potrzebna. Początkowo w sposób spontaniczny, następnie coraz bardziej planowy budowniczowie odpowiadali na zmieniające się potrzeby użytkowników. Śledząc rozwój miast, można zaobserwować dążenie do pewnej równowagi pomiędzy różnymi funkcjami miejskimi. Przemiany związane z rewolucją przemysłową, takie jak masowa migracja ludności do miast oraz silny rozwój transportu, spowodowały zaburzenie panującej harmonii i postawiły nowe wyzwania przed urbanistyką. W toku swej ewolucji miasta dostosowywały i wciąż dostosowują swoją zabudowę oraz place, skwery i ulice do bieżących potrzeb. Właśnie przestrzeń ulicy wraz z jej częściami składowymi znalazły się w centrum problematyki podejmowanej w niniejszej pracy. Głównym celem pracy była identyfikacja czynników wpływających na zachowania użytkowników przestrzeni publicznej, a konkretniej rzecz ujmując: zastanowieniu się czy fizyczne właściwości ulicy są bezpośrednio związane z wolą przebywania i czasem pozostawania ludzi w danej przestrzeni. W związku z tym, że szczególnie na ulicach znajdujących się w centrum miasta następuje duże nawarstwienie aktywności społecznych oraz zjawisk związanych z trudnościami transportowymi i strukturalnymi, zostały one wybrane jako temat rozważań.]]>
<![CDATA[Wykrywanie i identyfikacja uszkodzeń złożonego układu elektromechanicznego w ich początkowej fazie powstawania metodami falkowo-neuronowymi : rozprawa doktorska]]> Fri, 03 Apr 2020 17:04:12 +0200 Tomczyk, Marcin
rodzaj: rozprawa doktorska
Abstrakt: Rejestrowane w czasie rzeczywistym sygnały układów elektromechanicznych, zarówno elektryczne, jak i mechaniczne, zazwyczaj zawierają istotne informacje o stanie tych układów oraz o zachodzących w nich procesach fizycznych, mogących być symptomami pojawiających się uszkodzeń. W złożonych układach elektromechanicznych, zawierających silne nieliniowości, i działających w warunkach istnienia zakłóceń, dostęp do tych informacji jest zwykle bardzo trudny i wymaga stosowania specjalistycznego aparatu badawczego. Wymienione ograniczenia sprawiają, że wybór aparatu badawczego jest bardzo istotny. W rozprawie tej badania charakteru sygnałów przeprowadzono jednocześnie w dziedzinie czasu i częstotliwości, co zwiększyło efektywność selekcji zawartych w tych sygnałach informacji. Wybór ten był podyktowany dogłębną analizą istniejącego stanu wiedzy, która wykazała, że analiza czasowo-częstotliwościowa stanowi efektywne narzędzie monitorowania i diagnostyki niestacjonarnych stanów dynamicznych, które zazwyczaj są efektem występowania silnych nieliniowości (luzów, nieciągłości charakterystyk tłumienia, czy skokowych zmian momentu bezwładności). W pracy przyjęto, że analiza wrażliwości układu na niewielkie skokowe zmiany wartości wybranych parametrów układu może być pierwszym etapem badań takich stanów. W wyniku przeprowadzonych analiz stwierdzono, że zastosowanie metody sieci neuronowych, a także metody grupowania danych pozwala na wydatne zwiększenie efektywności wykorzystania informacji zawartej w rozkładach współczynników falkowych i skalogramach.]]>
<![CDATA[Dataset on flue gas composition during combustion in the fluidised bed reactor. Glycerol combustion]]> Fri, 03 Apr 2020 15:10:36 +0200 Żukowski, Witold; Berkowicz, Gabriela
rodzaj: artykuł w czasopiśmie
Abstrakt: The dataset presented in this article is the supplementary data for the research article by Żukowski and Berkowicz (doi:10.1016/j.combustflame.2019.05.024) [1], in which for the first time the inert and catalytic cenospheres were used as the fluidised bed material, giving the possibility to burn liquids inside the fluidised bed without the need for using specialized dosing systems. The instantaneous concentrations of the gaseous products during the combustion of glycerol samples were detected using Fourier Transform Infrared Spectroscopy (FTIR, Gasmet DX-4000). The accurate composition at the outlet of the reactor makes it possible to evaluate and verify new kinetic models of the glycerol combustion in the fluidised bed. It also will be helpful in creating new simplified models. The data presented here is essential for the evaluation of CFD combustion models which have to include accurate kinetic data.]]>
<![CDATA[Valuing groundwater quality in the Częstochowa case study (Poland)]]> Fri, 03 Apr 2020 15:00:40 +0200 Godyń, Izabela; Kountouris, Yiannis; Sauer, Johannes
rodzaj: artykuł w czasopiśmie
Abstrakt: This paper presents results of the study on preferences of inhabitants of the Częstochowa Region in Poland in the field of groundwater protection. The choice experiment (CE) method was applied, and willingness to pay (WTP) for improving groundwater quality through the development of sewerage systems was assessed. The results indicate that there is substantial WTP for water quality improvements. Households are willing to pay 18.25 PLN (4.43 EUR) per month to remain pollution at the maximum safe level according to EU regulations (reducing nitrate concentration in groundwater to 50 mg∙L-1). Our results add to the expanding literature on the valuation of water resources and can be useful in analysis of investment effectiveness, in the valuation of environmental costs and benefits related to improvement or deterioration of groundwater condition, and in the pricing policy debate in terms of fees and prices for water and water services.]]>
<![CDATA[Burzliwe dzieje kamienicy przy ulicy Szerokiej 12]]> Fri, 03 Apr 2020 14:08:51 +0200 Pierścionek, Marzena
rodzaj: opis bibliograficzny artykułu
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<![CDATA[New empirical model using landscape hydric potential method to estimate median peak discharges in mountain ungauged catchments]]> Fri, 03 Apr 2020 13:44:26 +0200 Wałęga, Andrzej; Młyński, Dariusz; Wojkowski, Jakub; Radecki-Pawlik, Artur; Lepeška, Tomáš
rodzaj: artykuł w czasopiśmie
Abstrakt: Designing hydraulic structures, such as culverts, bridges, weirs, and check dams, while planning new flood inundation areas, needs correct assessment of design discharges. In gauged catchments with long time series of discharges, statistical methods are commonly used based on fixed theoretical distributions and on empirical distributions. However, in ungauged catchments, this approach is not possible. In addition to more advanced methods, which are used today, e.g., rainfall–runoff models, much more simple approaches are still needed based on regionalization and empirical models. Thus, the objective of this work is to develop a new empirical model for calculating peak discharge expressed as the median of annual peak discharge (QMED). The innovative aspect of this paper is the use of a new parameter, named landscape hydric potential (LHP), as a descriptor of water storage in catchments. LHP has a crucial role as the descriptor of water storage in catchment and, thus, it has an influence on forming discharges. The work was done in the Upper Vistula basin in the Polish Carpathians. This study was carried out in mountain catchments located in the Upper Vistula basin, in the south part of Poland in in the Polish Carpathians. Results show that the proposed model could provide appropriate calculations in changing climate conditions, as well as when land use is changed. The proposed model is simple and effective; for calculating QMED, it needs only two parameters: catchment area and LHP. Since the model has a significant and high correlation coefficient, it could be used for assessing of QMED in ungauged mountain catchments. The determined form of the empirical equation finds application in the entire Upper Vistula basin, for catchments with a surface area from 24 km2 up to 660 km2.]]>
<![CDATA[A method-oriented approach to the formulation of algorithms for electrochemical kinetic simulations. Part 2. Extension to kinetic problems characterized by the simultaneous presence of bulk and interfacial species]]> Fri, 03 Apr 2020 13:38:23 +0200 Bieniasz, Lesław K.
rodzaj: artykuł w czasopiśmie
Abstrakt: The previously suggested method-oriented approach to the construction of algorithms of the numerical solution of initial boundary value problems occurring in electrochemical kinetics is extended to the class of kinetic problems characterized by the simultaneous presence of bulk species (distributed in the electrolyte) and interfacial species (localized at the electrodes). Such problems are described by coupled sets of partial differential and differential–algebraic equations, which in particular cases may also take the form of the sets of partial differential and algebraic equations, or partial differential and ordinary differential equations. Seven algorithms based on finite-difference discretizations are formulated, and their accuracy, efficiency and numerical stability are examined in calculations using typical examples of kinetic problems. An improvement of the coding of text input formulae and run-time interpretation of the codes, based on the idea of the three-address code in quadruple form, is also described.]]>
<![CDATA[Wolność słowa zakonspirowana w przestrzeni publicznej]]> Fri, 03 Apr 2020 13:12:28 +0200 Winskowski, Piotr
rodzaj: artykuł w czasopiśmie
Abstrakt: Artykuł przedstawia strategie reprezentowania idei w przestrzeni publicznej w przeciągu drugiej połowy XX wieku z naciskiem nie na klasyczne pomniki-obiekty lecz na strategie takiej modyfikacji parametrów „pustej” przestrzeni, aby jej ukształtowanie stało się nośnikiem zamierzonych treści. Gdy tą treścią jest sprawa wolności słowa, a zadaniem – upamiętnienie ludzi zasłużonych dla tej sprawy ‒ stawia to przed projektantami specyficzne, a chwilami rozbieżne wymagania. Jeden ze sposobów, w jaki starano się sprostać tym wymaganiom, ilustruje koncepcja konkursowa Memoriału Wolnego Słowa w Warszawie (2013) autorstwa Katarzyny Wojtygi, Olafa Ciruta, Piotra Winskowskiego i Jacka Godlewskiego.]]>
<![CDATA[Studenckie projekty Centrum "Nowy Hrubieszów" ]]> Fri, 03 Apr 2020 13:09:49 +0200 Gierbienis, Marcin
rodzaj: artykuł w czasopiśmie
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<![CDATA[Automatic derivation of the governing equations that describe a transient electrochemical experiment, given a reaction mechanism of arbitrary complexity. Part 1. Problem parameters and initial conditions]]> Fri, 03 Apr 2020 12:03:28 +0200 Bieniasz, Lesław K.
rodzaj: artykuł w czasopiśmie
Abstrakt: We describe a systematic procedure for determining a self-consistent set of thermodynamic and kinetic parameters and initial conditions that are needed for the simulation of transient electrochemical experiments, given a reaction mechanism of arbitrary complexity. This is an extension of the algorithm recently suggested by Luo et al. (J. Electroanal. Chem., 368 (1994) 109) to the larger class of reaction networks involving elementary or non-elementary electrochemical, heterogeneous non-electrochemical and homogeneous reactions of unrestricted molecularities, subject to the power rate law with reaction orders that can be different from stoichiometric coefficients. Equilibrium, non-equilibrium reversible and irreversible reactions between bulk species (distributed in the electrolyte) and interfacial species (located at electrodes) are allowed, as well as the presence of species with invariant concentrations. Tests enabling verification of the correctness of the symbolically written reaction mechanisms are described. The procedure is part of an algorithm for automatic, computer-aided translation of electrochemical reaction mechanisms into corresponding texts of mathematical governing equations.]]>
<![CDATA[Refinement of the Hardening Soil model within the small strain range]]> Fri, 03 Apr 2020 11:40:06 +0200 Cudny, Marcin; Truty, Andrzej
rodzaj: artykuł w czasopiśmie
Abstrakt: The popularity of the elasto-plastic Hardening Soil (HS) model is based on simple parameter identification from standard testing and empirical formulas. The HS model is implemented in many commercial FE codes designed to analyse geotechnical problems. In its basic version, the stress–strain behaviour within the elastic range is subject to the hypoelastic power law, which assures the barotropy of the elastic stiffness. However, a proper modelling within the small strain range, i.e. strain-induced stiffness degradation and correct reproduction of the hysteretic behaviour, was one of the most important drawbacks in the HS formulation. The first small strain stiffness extension to the HS model was proposed by Benz (Small strain stiffness of soils and its numerical consequences, 2007), and the new model was called Hardening Soil Small (HSS). Despite the simple isotropic formulation, its applicability was proved in various numerical simulations in geotechnics. However, the HSS formulation exhibits a serious fault known in the literature as overshooting, i.e. uncontrolled reset of the loading memory after tiny unloading–reloading cycles. The authors’ main aim was to retain the set of material parameters for the HSS formulation and to propose a new small strain extension to the HS model without overshooting. The new proposal is based on the BRICK model which represents the concept of nested yield surfaces in strain space. The implementation aspects of the new HS-Brick model are described, and its performance is presented in some element tests and selected boundary value problems by comparisons with the HSS formulation.]]>
<![CDATA[Automatic derivation of the governing equations that describe a transient electrochemical experiment, given a reaction mechanism of arbitrary complexity. Part 2. Governing equations in one-dimensional geometry]]> Fri, 03 Apr 2020 11:16:06 +0200 Bieniasz, Lesław K.
rodzaj: artykuł w czasopiśmie
Abstrakt: A systematic procedure for deriving the governing equations that describe a transient electrochemical experiment, given a reaction mechanism of arbitrary complexity under conditions of controlled-potential or controlled-current transients methods, is outlined. The procedure is based on the analysis and transformations of the stoichiometric matrix and other data, and applies to the class of reaction networks involving electrochemical, heterogeneous non-electrochemical and homogeneous reactions between bulk species (subject to semi-infinite diffusion and/or convection in one-dimensional spatial geometry) and interfacial species (located at electrodes). Equilibrium, non-equilibrium reversible and irreversible reactions are allowed, as well as the presence of species with invariant concentrations. The corresponding governing equations are proven to take the form of coupled sets of partial differential equations with initial and boundary conditions (for the concentrations of bulk species), and differential-algebraic equations (for the concentrations of interfacial species). The procedure is a part of the algorithm of an automatic, computer-aided translation of electrochemical reaction mechanisms into corresponding texts of the governing equations.]]>
<![CDATA[Ensemble residual network-based gender and activity recognition method with signals]]> Fri, 03 Apr 2020 10:33:10 +0200 Tuncer, Turker; Ertam, Fatih; Dogan, Sengul; Aydemir, Emrah; Pławiak, Paweł
rodzaj: artykuł w czasopiśmie
Abstrakt: Nowadays, deep learning is one of the popular research areas of the computer sciences, and many deep networks have been proposed to solve artificial intelligence and machine learning problems. Residual networks (ResNet) for instance ResNet18, ResNet50 and ResNet101 are widely used deep network in the literature. In this paper, a novel ResNet-based signal recognition method is presented. In this study, ResNet18, ResNet50 and ResNet101 are utilized as feature extractor and each network extracts 1000 features. The extracted features are concatenated, and 3000 features are obtained. In the feature selection phase, 1000 most discriminative features are selected using ReliefF, and these selected features are used as input for the third-degree polynomial (cubic) activation-based support vector machine. The proposed method achieved 99.96% and 99.61% classification accuracy rates for gender and activity recognitions, respectively. These results clearly demonstrate that the proposed pre-trained ensemble ResNet-based method achieved high success rate for sensors signals.]]>
<![CDATA[Potato starch utilization in ecological loose-fill packaging materials – sustainability and characterization]]> Fri, 03 Apr 2020 10:30:57 +0200 Combrzyński, Maciej; Karcz, Dariusz
rodzaj: artykuł w czasopiśmie
Abstrakt: Biodegradable materials are used in the manufacture of packaging and compostable films and various types of medical products. These have demonstrated high potential in medical applications: cardiac, vascular and orthopaedic conditions in adults as well in children. In our research, the extrusion-cooking technique was used to obtain environmentally friendly loose-fill foams as packaging. Potato starch was the basic raw material. Polyvinyl alcohol was used as an additive in the amount of 1%, 2% and 3% to replace starch. The components were mixed and moistened with water to various initial moisture contents of the blend (17%, 18% and 19%). The processing of starch foams employed the TS-45 single screw extruder-cooker (Gliwice, Poland) with the L/D ratio of 12. The foams were processed with various screw speeds (100 and 130 rpm) and with two types of forming dies (circular and ring die). The extrusion-cooking process efficiency (kg h−1 ) and the energy consumption (kWh kg−1 ) during the processing were also measured. The results showed that the processing efficiency of potato starch foams varied depending on the level of polyvinyl alcohol, the shape of the forming die and the screw speed applied. The analysis of energy consumption, mechanical properties and FTIR analyses demonstrated that the type of the forming die and the initial moisture level had the most significant impact on specific energy demands during the processing of potato starch-based foams.]]>
<![CDATA[Vertical dynamic loads on footbridges generated by people running]]> Fri, 03 Apr 2020 09:20:58 +0200 Pańtak, Marek
rodzaj: artykuł w czasopiśmie
Abstrakt: This paper concerns the issue of the dynamic impact of people running on footbridges with particular with attention to various footstrike patterns occurring during the running (i.e. heel strike pattern and forefoot strike pattern). The results of a series of laboratory tests of vertical ground reaction force (VGRF) measurements generated by running people are presented along with the characteristics of the VGRF curves. Based on the results of the tests, a new proposal for a dynamic load model generated by people classified as heel strike runners has been developed, and corrections of the input parameters of two load models proposed by other authors have been performed. Moreover, the VGRF modelling technique using the Gaussian functions is presented along with a set of equations describing the variability of the Gaussian function parameters as a function of the frequency of running. The presented methods of the VGRF modelling allow increasing the accuracy of determining the VGRF values and, consequently, increasing the accuracy of dynamic analyses of footbridges subjected to dynamic loads generated by people running.]]>
<![CDATA[History of origin and development, compositional and morphological features of park pavilions in Ancient China]]> Thu, 02 Apr 2020 14:31:03 +0200 Ivashko, Yulia; Kuśnierz-Krupa, Dominika; Peng, Chang
rodzaj: artykuł w czasopiśmie
Abstrakt: The article analyses the origins of such a small architectural form as the Chinese pavilion, investigates its functional, planning and artistic figurative features. The evolution of functional and artistic figurative solution of pavilions from dynasty to dynasty is determined. On the basis of the dimensions of the preserved pavilions, their proportional and metro-rhythmic features were determined; a list of the most characteristic forms of roofs as the main exponents of the national originality of the Chinese pavilions was compiled. The reasons for the revival of the tradition of "chinoiserie" style in modern landscape design are argued.]]>
<![CDATA[Use of sensitivity analysis methods in the modelling of electrochemical transients. Part 2. Model expansion and model reduction]]> Thu, 02 Apr 2020 12:03:04 +0200 Bieniasz, L. K.; Dümmling, S.; Speiser, B.; Würde, M.
rodzaj: artykuł w czasopiśmie
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<![CDATA[Comments on the paper by M. Rudolph, entitled "Digital simulations on unequally spaced grids. Part 1. Critical remarks on using the point method by discretisation on a transformed grid" [J. Electroanal. Chem. 529 (2002) 97]]]> Thu, 02 Apr 2020 11:47:42 +0200 Bieniasz, L. K.
rodzaj: artykuł w czasopiśmie
Abstrakt: According to the recent suggestion by M. Rudolph [J. Electroanal. Chem. 529 (2002) 97], the point method of the finite-difference electrochemical simulations suffers from a considerable loss of accuracy, when used in conjunction with moderately or strongly non-uniform exponentially expanding spatial grids defined by coordinate transformation. Furthermore, Rudolph concludes that when using a three-point approximation for the second spatial derivative, the point method cannot be better than first-order accurate in such cases. These opinions are debatable because they have been confirmed by the examination of only two variants of the point method. We investigate an alternative variant of the point method, also based on a three-point discretisation of the second spatial derivative on the uniform grid of the transformed space coordinate. This discretisation contradicts the Rudolph opinions because it is second-order accurate and it provides distinctly more accurate results than the variants considered by Rudolph. This is demonstrated for the example of the simulation of the potential step chronoamperometry under limiting current conditions at a planar electrode.]]>
<![CDATA[Use of sensitivity analysis methods in the modelling of electrochemical transients: Part 3. Statistical error/uncertainty propagation in simulation and in nonlinear least-squares parameter estimation]]> Thu, 02 Apr 2020 11:11:54 +0200 Bieniasz, L. K.; Speiser, B.
rodzaj: artykuł w czasopiśmie
Abstrakt: Sensitivity information obtained by means of a local direct method can be useful in performing various tasks associated with the analysis of the statistical error propagation in the solution of forward and inverse problems in the modelling of electrochemical transients. First- and second-order sensitivity coefficients of the transient curves with respect to model parameters play a crucial role in the formalism presented, which links errors of known parameters, errors of parameters estimated by single or multiresponse nonlinear least-squares fitting of the entire transient curves or their features, and errors of the transient curves. Uncertainty analysis of the simulated transient curves, so far unpractised in electrochemical kinetics, can be performed. Error analysis of parameters estimated using direct search (e.g. simplex) or other types of least-squares minimisation, pointwise analysis of the variances of estimated parameters, least-squares gradient-based minimisation, or identification of deterministic correlations between parameters, can be performed easily, and/or more efficiently or reliably compared with formerly used techniques. Some of these features are demonstrated by making a detailed error/uncertainty analysis of linear potential scan and cyclic voltammetric transients for a quasi-reversible charge-transfer reaction, assuming one known but uncertain parameter (charge-transfer coefficient), and two unknown parameters (heterogeneous electron transfer rate constant and formal potential).]]>
<![CDATA[Three-dimensional analysis of laminated plates with functionally graded layers by two-dimensional numerical model]]> Thu, 02 Apr 2020 09:03:02 +0200 Pluciński, Piotr; Jaśkowiec, Jan
rodzaj: artykuł w czasopiśmie
Abstrakt: This work presents a three-dimensional (3D) numerical analysis of multi-layered laminated plates in which selected layers may be made of functionally graded material (FGM), in which the Young’s modulus may change along the thickness as a consequence of a continuous and graded mixture of two materials. For the analysis, the method, known as FEM23, is applied, which uses a two-dimensional (2D) mesh, yet enables obtaining full 3D results for the layered structure. In FEM23, the layered structure may be a combination of thin and thick layers made of materials with significantly different properties. This paper presents two examples comparing the results to other numerical or analytical solutions. The examples confirm the correctness and flexibility of FEM23 for laminated plates with functionally graded layers.]]>
<![CDATA[Analiza wykorzystania płyty postojowej w Międzynarodowym Porcie Lotniczym im. Jana Pawła II w Krakowie]]> Thu, 02 Apr 2020 09:01:25 +0200 Bryniarska, Zofia; Pindel, Iwona
rodzaj: artykuł w czasopiśmie
Abstrakt: John Paul II International Airport Krakow-Balice is an airport that is developing very dynamically. The number of serviced passengers increases year by year. For this reason, the airport is constantly being extended. At the end of 2016, a new terminal was opened, now also the apron is renovated. The article is to analyse the use of the apron before construction works and reorganization of the plate. The calculations were made to check the apron use and, in the future, to be able to compare them with the analysis of the refurbished apron. The analysis was performed on the basis of the data containing information on the number of aviation operations registered during one year, including actual and scheduled times of flight operations - arrivals and departures along with the allocated number of the parking stand at the apron. An analysis includes the usage of apron and its individual aircraft stands throughout the entire analysed period and the size of aircraft standstill times, including the division into traditional and low-cost airlines. The use of the apron and its individual stands on the day of the largest number of aircraft accepted by the airport was analysed. The summary contains the most important conclusions from the analysis and the calculated values that characterize: the use of the apron on the day with the largest number of operations, the occupancy of individual positions in the examined period, the average aircraft standstill times.]]>
<![CDATA[Analiza pracy podkładu kolejowego przy uwzględnieniu sprężenia prętami]]> Wed, 01 Apr 2020 16:04:43 +0200 Urbanek, Małgorzata; Dziewoński, Paweł
rodzaj: materiały konferencyjne w czasopiśmie
Abstrakt: Artykuł przedstawia pracę podkładu kolejowego pod wpływem obciążenia eksploatacyjnego. Wykorzystując model numeryczny ustalono przemieszczenia pionowe dla dwóch typów podkładu - PS-94 i PS-08 oraz określono wpływ zastosowania prętów sprężonych.]]>
<![CDATA[Konserwacja kamienicy przy ulicy Szerokiej 12]]> Wed, 01 Apr 2020 12:50:13 +0200 Cempla-Dziadoń, Ewa
rodzaj: opis bibliograficzny artykułu
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<![CDATA[Finite-difference electrochemical kinetic simulations using the Rosenbrock time integration scheme]]> Wed, 01 Apr 2020 12:14:33 +0200 Bieniasz, L. K.
rodzaj: artykuł w czasopiśmie
Abstrakt: Temporal integration based on multistep backward differentiation formulae may not be the best choice for finite-difference electrochemical kinetic simulations. A one-step, highly accurate, unconditionally stable and non-oscillatory implicit time scheme that also provides temporal error estimates, would be more desirable. The Lawson–Morris–Gourlay extrapolation (LMGE) method, suggested by Strutwolf and Schoeller, partially satisfies these requirements, but it is computationally rather expensive, especially for nonlinear governing equations. The Rosenbrock method, thus far unused in electrochemical simulations, is shown here to be competitive. By combining a three-stage ROWDA3 Rosenbrock method for differential–algebraic equations (DAEs), with a finite-difference spatial discretization of the governing equations, an effective simulation algorithm can be obtained. This is demonstrated for three example kinetic models represented by a single reaction–diffusion equation in one space dimension: potential step experiment, linear sweep voltammetry for a first- and second-order irreversible heterogeneous charge transfer, and linear sweep voltammetry for an enzymatic catalytic reaction mechanism. Numerical properties of the algorithm are compared in calculations with those of the finite-difference methods based on first- and second-order backward differentiation formulae, the Crank–Nicolson (CN) method, and the second-order LMGE method. Fixed, uniform grids are used. Under conditions of a large temporal-to-spatial grid step ratio, important for electrochemical simulations, the third-order accurate ROWDA3 integration proves more efficient than the second-order extrapolation method. In one case it is also more efficient than the method based on the second-order (two-step) backward differentiation formula.]]>
<![CDATA[Regulacja hydrauliczna a efektywność i komfort. Ręczne zawory równoważące i zawory mieszające oraz rozdzielające]]> Wed, 01 Apr 2020 11:41:54 +0200 Muniak, Damian
rodzaj: artykuł w czasopiśmie
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<![CDATA[Rešenie kinetičeskih uravnenij v nestacionarnyh usloviâh dlâ èlektrohimičeskoj reakcii soprovoždaemoj himičeskoj kataličeskoj reakciej]]> Wed, 01 Apr 2020 09:22:36 +0200 Benâš, L.
rodzaj: materiały konferencyjne w książce
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<![CDATA[Hydro-climatic trends in mountain catchments (Polish Eastern Carpathians)]]> Wed, 01 Apr 2020 08:58:53 +0200 Kędra, Mariola
rodzaj: materiały konferencyjne w książce
Abstrakt: In a changing climatic conditions and rising surface air temperatures, mountain areas with their characteristic environment and accumulated snow deserve special attention and sustainable management. Thick snowpacks, usually lying in the mountains for most of the year, are valuable resources of fresh water, supplying streams and rivers during spring and summer thaws, that is, during the vegetation period. Obviously, as the air temperature rises, snow melting begins earlier and lasts shorter, while the vegetation requires more water to grow. In this context, updated information on available water resources and their potential changes, including hydro-climatic trends, is necessary to enable sustainable management of mountain areas. The aim of the study was to examine potential trends in hydro-climatic variables (river flow, precipitation and surface air temperature) for the medium-height mountain catchments located in the Polish Eastern Carpathians. The monthly data covering the period 1957–2016 (60 years) were made available for research purposes by the Polish Institute of Meteorology and Water Management—the National Research Institute. In order to assess the magnitude of hydro-climatic trends, the Mann-Kendall test with the trend-free pre-whitening procedure was used. Research has shown that long-term monotonic trends are significant (p<0.05) mainly for air temperature, both on annual and monthly basis (for months from April to August). Increasing trends in air temperature are accompanied by less frequent, but significant trends in precipitation, with increases in precipitation for January and May, but a decrease in precipitation for December. For river flow, significant increasing trends were found only for January, in line with precipitation trends.]]>
<![CDATA[Resistance of insulating-structural concretes to high temperature]]> Tue, 31 Mar 2020 14:48:02 +0200 Domagała, Lucyna
rodzaj: materiały konferencyjne w czasopiśmie
Abstrakt: The aim of this paper is to assess durability of concretes made of expanded glass, perlite and polystyrene aggregates exposed to high temperature. The following tests of four concretes, used in practice for insulating-structural applications, were carried out: density in saturated, natural and oven-dry state, compressive and flexural strength at the curing temperature and after heating at the temperature of 100 oC, 200 oC, 300 oC and 400 oC. The tests results showed that applied high temperatures affected the properties of concretes in different way depending on their compositions. Nevertheless, all four composites retained sufficient strength to be still regarded as insulating-structural concretes.]]>
<![CDATA[Multisensoryczne przestrzenie publiczne. Zasady tworzenia multisensorycznych otwartych stref nauki i rekreacji : praca doktorska]]> Tue, 31 Mar 2020 14:35:29 +0200 Tota, Paulina
rodzaj: rozprawa doktorska
Abstrakt: Dla dzieci i młodzieży niewidomych i słabowidzących podstawowym problemem jest zapewnienie wszechstronnego rozwoju. Współczesna tyflopedagogika w większości realizuje ogólnorozwojowy program przystosowania tej grupy do pełnej socjalizacji w środowisku osób widzących, jednak obok tyflopedagogiki i tyflorehabilitacji istnieje również szereg rozwiązań przestrzennych, które w znaczący sposób mogą przyczyniać się do zwiększenia samodzielności i podniesienia jakości funkcjonowania w środowisku miejskim osób z niepełnosprawnością wzroku. Za szczególnie istotne uważane są właściwie zaprojektowane i wykonane miejskie przestrzenie publiczne, w tym także przestrzenie edukacji i rekreacji. Celem pracy jest określenie bezpośrednich powiązań pomiędzy układem przestrzennym a jego wpływem na ogólną jakość życia, a w szczególności rehabilitację i codzienne funkcjonowanie dzieci i młodzieży z niepełnosprawnością wzroku a także – rozpoznanie przemian i aktualnie wiodących tendencji w projektowaniu szczególnego rodzaju miejskich przestrzeni publicznych, jakimi są multisensoryczne otwarte strefy nauki i rekreacji.]]>
<![CDATA[Assessment of the spatial distribution of moisture content in granular material using Electrical Impedance Tomography]]> Tue, 31 Mar 2020 13:45:23 +0200 Porzuczek, Jan
rodzaj: materiały konferencyjne w książce
Abstrakt: This paper presents a method for on-line determination of the spatial distribution of the moisture content in granular material. It might be essential for monitoring and optimal control of e.g. drying processes. The proposed method utilizes Electrical Impedance Tomography (EIT). As the exemplary material for experimental research the black chokeberry (Aronia melanocarpa) was used. The relationship between electrical impedance of chokeberry and its moisture content was determined for wide range of frequency (20Hz-200kHz). The EIT research consisted of both simulation as well as experimental investigation. Experimental studies of the spatial distribution of the moisture content was performed in the cylindrical vessel equipped with 8-electrode circumferentially arranged. Voltage signal from the electrodes was acquired simultaneously using data acquisition module. Due to high impedance of the chokeberries, exceeding 10^9 ohm for dried matter, extraordinary instrumentation was necessary to be applied. On the other hand raw chokeberry is characterized by several orders of magnitude lower impedance (10^3-10^4 ohm) especially for high frequency. Wide range of observed impedance was able to be measured owing to use of the voltage stimulation instead of the current stimulation (which is most common for EIT). The image reconstruction problem was solved using iterative Gauss-Newton algorithm and the EIDORS software package. The obtained results showed satisfactory ability to localize insufficiently dried part of the material. Prospect for the improvement of the imaging quality was also discussed.]]>
<![CDATA[Chronopotentiometry at a microband electrode: simulation study using a Rosenbrock time integration scheme for differential–algebraic equations and a direct sparse solver]]> Tue, 31 Mar 2020 13:31:42 +0200 Bieniasz, L. K.; Britz, D.
rodzaj: artykuł w czasopiśmie
Abstrakt: Two-dimensional digital simulation of chronopotentiometry at a microband electrode cannot be performed by conventional alternating direction implicit finite-difference simulation methods, as a result of non-local boundary conditions at the electrode. It is also potentially troublesome for iterative Krylov algorithms for solving linear algebraic equations that result from implicit temporal integration schemes. These difficulties can be avoided by representing the spatially discretised initial boundary value problem in the form of a set of differential–algebraic equations, to which a suitable integration scheme, such as the Rosenbrock ROWDA3 scheme, can be applied. The resulting linear algebraic equations can be solved unfailingly by a general direct sparse algorithm such as Y12M. Using this technique it has been found that the chronopotentiometric potential–time curves and transition time characteristics of a single charge transfer reaction at a microband electrode resemble those for a microhemicylinder electrode of the same surface area, although transition times are somewhat shorter. The simulation reveals also that the assumption of a uniform flux of the concentration at the electrode, encountered in the literature in the context of the two-dimensional theories of chronopotentiometry at microelectrodes, is not adequate, owing to non-negligible edge effects observed.]]>
<![CDATA[Problem adaptacji zabytkowych kamienic na cele hotelowe na przykładzie Hotelu Rubinstein]]> Tue, 31 Mar 2020 12:10:54 +0200 Zalewski, Władysław
rodzaj: opis bibliograficzny artykułu
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<![CDATA[Refleksje na temat prac budowlano-konserwatorskich przy ulicy Szerokiej 12]]> Tue, 31 Mar 2020 11:59:01 +0200 Sarnik-Konieczna, Maria
rodzaj: opis bibliograficzny artykułu
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<![CDATA[Analiza przepływów materiałowych jako narzędzie w wyborze kryteriów oceny wielokryterialnej różnych wariantów spalarni odpadów komunalnych]]> Tue, 31 Mar 2020 10:20:09 +0200 Generowicz, Agnieszka; Kulczycka, Joanna; Kowalski, Zygmunt
rodzaj: artykuł w czasopiśmie
Abstrakt: Porównano 4 spalarnie odpadów komunalnych pod względem ich oddziaływania na środowisko, stosując analizę przepływów materiałowych i analizę multikryterialną. Sporządzono bilanse materiałowe spalarni. Najkorzystniejsza okazała się spalarnia w Wuppertal (Niemcy).]]>
<![CDATA[Two new compact finite-difference schemes for the solution of boundary value problems in second-order non-linear ordinary differential equations, using non-uniform grids]]> Tue, 31 Mar 2020 10:08:07 +0200 Bieniasz, L. K.
rodzaj: artykuł w czasopiśmie
Abstrakt: Two new finite-difference, three-point compact discretisations of boundary value problems in second-order non-linear ordinary differential equations: U(2)(x)−F(x, U(x),U(1)(x)) = 0, applicable to non-uniform grids, are derived and compared in calculations with three previously published methods. The discretisations are modifications of the efficient uniform-grid arithmetic average method of Chawla and Shivakumar [Neural Parallel Sci. Comput. 4 (1996) 387–396]. Formal error analysis reveals that the truncation errors of the new discretisations are of third order with respect to the local grid spacings. New, economical, fourth-order accurate, two-point compact approximations to the first derivatives of the solution at the boundaries are also designed. Numerical experiments with the solution of singularly perturbed example problems, characterized by boundary and interior layers, indicate that the practical orders of accuracy of the new schemes are close to four, even for non-uniform grids. The methods prove competitive with the three-point extension of the Numerov method, and with one other extension of the Chawla and Shivakumar method.]]>
<![CDATA[Odzyskane piękno – opinie i spostrzeżenia]]> Mon, 30 Mar 2020 14:44:51 +0200 rodzaj: opis bibliograficzny artykułu
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<![CDATA[Krakowski Kazimierz. Trasy turystyczne Krakowa, cz. IV]]> Mon, 30 Mar 2020 13:49:47 +0200 Skrzypek, Beata; Pomykalski, Paweł
rodzaj: opis bibliograficzny artykułu
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<![CDATA[Use of dynamically adaptive grid techniques for the solution of electrochemical kinetic equations. Part 14: extension of the patch-adaptive strategy to time-dependent models involving migration–diffusion transport in one-dimensional space geometry, and its application to example transient experiments described by Nernst–Planck–Poisson equations]]> Mon, 30 Mar 2020 09:11:36 +0200 Bieniasz, L. K.
rodzaj: artykuł w czasopiśmie
Abstrakt: The finite-difference patch-adaptive strategy for electrochemical kinetic simulations, introduced in Part 5 and extended in Part 10 of this series of papers, is further extended to time-dependent models involving migration–diffusion transport in one-dimensional space geometry. The extensions include: spatial discretisation of generalised second spatial derivative expressions typical of migration–diffusion equations; allowance for the dependence of boundary conditions on displacement current; support for an a posteriori calculation of the displacement current as one of the model responses; optional calculation of steady-state initial conditions; the ability to use enhanced precision of floating point calculations. The extended strategy is used to simulate four examples of transient experiments, represented by Nernst–Planck–Poisson equation systems: coulostatic charge injection at an ideally polarised planar electrode; a voltage step for a thin layer asymmetric electrochemical cell; chronopotentiometry for an electrolyte|membrane|electrolyte system; and chronopotentiometry for a bipolar membrane. The strategy provides fairly reliable solutions, but its automatism and efficiency are less satisfactory compared to models without electric migration, owing to the need for model-dependent tuning of the method parameters, and increased computational cost necessary for the exact adaptive determination of the electric potential profiles.]]>
<![CDATA[Impact of the deionized water on making high aspect ratio holes in the Inconel 718 alloy with the use of electrical discharge drilling]]> Mon, 30 Mar 2020 07:31:38 +0200 Machno, Magdalena; Bogucki, Rafał; Szkoda, Maciej; Bizoń, Wojciech
rodzaj: artykuł w czasopiśmie
Abstrakt: Nickel-based superalloys are being increasingly applied to manufacture components in the aviation industry. The materials are classified as dicult-to-machine using conventional methods. Nowadays, manufacturing techniques are needed to drill high aspect ratio holes of above 20:1 (depth-to-diameter ratio) in these materials. One of the most e ective methods of making high-aspect-ratio holes is electrical discharge drilling (EDD). While drilling high aspect ratio holes, a crucial issue is the flushing of the gap area and the evacuation of the erosion products. The use of deionized water as the dielectric fluid in the EDD o ers a considerable potential. This paper includes an analysis of the influence of the machining parameters (pulse time, current amplitude and discharge voltage) on the process performance (drilling speed, linear tool wear, taper angle, hole’s aspect ratio, side gap thickness), during the EDD with the use of deionized water in the Inconel 718 alloy. The obtained through holes were subjected to the extended analysis. The impact of the initial working fluid temperature and pressure on the conditions of the flow through the electrode channel was also subjected to the analysis. The deionized water properties were changed by applying an initial temperature. Based on the results of an analysis of the previous research, the EDD of the through holes was performed for a pre-set initial temperature (~313.15 K) and initial pressure of the working fluid (8 MPa) and selected process parameters. An analysis of the results indicates increasing of hole’s aspect ratio by about 15% (above 30), decreasing the side gap thickness by about 40% and enhanced surface integrity.]]>