2020 - Repozytorium publikacji - Politechnika Gdańska

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Theoretical and Actual Feed Per Tooth During Wood Sawing on an Optimizing Cross-Cut Saw
- Kazimierz Orłowski
- Wojciech Blacharski
- Daniel Chuchała
- Przemysław Dudek
2020 Pełny tekst
The work presents the geometries of circular saw teeth, whose task is to divide the cross-cut of the cutting layer. For efficient machining on a cross-cut saw with high feed speed values (about 1 ms−1) maximal theoretical feeds per tooth are determined. These values were compared with the actual values determined during transverse cutting of pine wood on a special test stands in industrial conditions. In the experiment the rotational speed of the main driving motor and the feed speed of the saw blade were simultaneously measured. Unique experimental results revealed that the feed driving system with the crank mechanism driven with the rotary servo motor only the phenomenon of the decrease in the spindle rotational speed was present, which caused a slight increase of the feed per tooth. In the case of the pneumatic actuator applied in the feeding driving system its flexibility together with larger changes in feed speed additionally were observed. For that reason in a new cross-cut saw for the feeding system driven by the crank mechanism with the rotary servo motor ought to be recommended.
Theoretical and Economic Evaluation of Low-Cost Deep Eutectic Solvents for Effective Biogas Upgrading to Bio-Methane
- Edyta Słupek
- Patrycja Makoś
- Jacek Gębicki
2020 Pełny tekst ENERGIES
This paper presents the theoretical screening of 23 low-cost deep eutectic solvents (DESs) as absorbents for effective removal of the main impurities from biogas streams using a conductor-like screening model for real solvents (COSMO-RS). Based on thermodynamic parameters, i.e., the activity coefficient, excess enthalpy, and Henry’s constant, two DESs composed of choline chloride: urea in a 1:2 molar ratio (ChCl:U 1:2), and choline chloride: oxalic acid in a 1:2 molar ratio (ChCl:OA 1:2) were selected as the most effective absorbents. The σ-profile and σ-potential were used in order to explain the mechanism of the absorptive removal of CO2, H2S, and siloxanes from a biogas stream. In addition, an economic analysis was prepared to demonstrate the competitiveness of new DESs in the sorbents market. The unit cost of 1 m3 of pure bio-methane was estimated to be in the range of 0.35–0.37 EUR, which is comparable to currently used technologies.
Theoretical and Experimental Studies on the Visible Light Activity of TiO2 Modified with Halide-Based Ionic Liquids
- Marta Paszkiewicz-Gawron
- Samanta Makurat
- Janusz Rak
- Magdalena Zdrowowicz
- Wojciech Lisowski
- Adriana Zaleska-Medynska
- Kowalska Ewa
- Paweł Mazierski
- Justyna Łuczak
2020 Pełny tekst Catalysts
Formation of a surface complex between organic molecules and TiO2 is one of the possible strategies for the development of visible light-induced TiO2 photoactivity. Herein, three ionic liquids (ILs) with the same cation and dierent anions (1-butylpirydynium chloride/bromide/iodide) have been applied for the surface modification of TiO2 and to understand the role of anions in visible light-induced activity of ILs-TiO2 systems. Photocatalytic screening tests (the measurements of phenol photodegradation reaction rate) revealed that anion type aected visible light activity ( > 420 nm) of TiO2 obtained by the ILs-assisted solvothermal method. Density functional theory (DFT) calculations demonstrated that interactions between halogen anions and oxygen vacancies (OV) on the surface of the TiO2 particles could be responsible for the specific wavelength-induced excitation and finally for the observed photoactivity of titania under visible light. Finally, our theoretical calculations have been proven by experiments using monochromatic light (the apparent quantum eciency was measured) and the properties of obtained samples were characterized using scanning electron microscopy (SEM), X-ray powder
Theoretical and experimental study on scattering of low-energy electrons by dimethyl and diethyl ethers
- Gillian Tatreau
- Borna Hlousek
- Mateusz Zawadzki
- Murtadha Khakoo
- Fernanda P Bardela
- Alessandra Souza Barbosa
- Márcio H F Bettega
2020 JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
We report a joint theoretical and experimental investigation on low-energy electron scattering by dimethyl and diethyl ethers. The experimental elastic differential cross sections were measured at impact energies from 1 eV up to 30 eV and scattering angle range of 10◦ to 130◦. Theoretical elastic differential, integral and momentum-transfer cross sections are calculated at impact energies up to 30 eV, employing the Schwinger multichannel method implemented with norm-conserving pseudopotentials, in the static-exchange and static-exchange plus polarization approximations. Our experimental and theoretical results for dimethyl and diethyl ether are compared with previous data for their isomers, ethanol and butanol, respectively. These comparisons reveal that although the cross sections for the ether and its respective alcohol present similar magnitudes, the angular behavior of their differential cross sections shows some significant differences. From the analysis of the integral cross sections for electron scattering by dimethyl and diethyl ether, we observe a broad structure, at around 9.5 eV, which we assign as the overlap of several resonant structures.
Therapeutic Potential of Carnosine and Its Derivatives in the Treatment of Human Diseases
- Klaudia Chmielewska
- Krystyna Dzierzbicka
- Iwona Inkielewicz-Stępniak
- Maja Przybyłowska
2020 Pełny tekst CHEMICAL RESEARCH IN TOXICOLOGY
Despite significant progress in the pathogenesis, diagnosis, treatment, and prevention of cancer and neurodegenerative diseases, their occurrence and mortality are still high around theworld. The resistance of cancer cells to the drugs remains a significant problem in oncology today,while in the case of neuro-degenerative diseases, therapies reversing the process are still yet to be found. Furthermore, it is important to seek new chemotherapeutics reversing side effects of currently used drugs or helping them perform their function to inhibit progression of the disease. Carnosine, a dipeptide constisting of β-alanine and L-histidine, has a variety of functions to mention: antioxidant, antiglycation, and reducing the toxicity of metal ions. It has therefore been proposed to act as a therapeutic agent for many pathological states. The aim of this paper was to find if carnosine and its derivatives can be helpful in treating various diseases. Literature search presented in this review includes review and original papers found in SciFinder, PubMed, and Google Scholar. Searches were based on substantial keywords concerning therapeutic usage of carnosine and its derivatives in several diseases including neurodegenerative disorders and cancer. In this paper, we review articles and find that carnosine and its derivatives are potential therapeutic agents in many diseases including cancer, neurodegenerative diseases, diabetes, and schizophrenia. Carnosine and its derivatives can be used in treating neurodegenerative diseases, cancer, diabetes, or schizophrenia, although their usage is limited. Therefore, there’s an urge to synthesize and analyze new substances,vercoming the limitation of carnosine itself.
Thermal Biomass Conversion: A Review
- Witold Lewandowski
- Michał Ryms
- Wojciech Kosakowski
2020 Pełny tekst Processes
In this paper, the most important methods of thermal conversion of biomass, such as: hydrothermal carbonization (180–250 °C), torrefaction (200–300 °C), slow pyrolysis (carbonization) (300–450 °C), fast pyrolysis (500–800 °C), gasification (800–1000 °C), supercritical steam gasification, high temperature steam gasification (>1000 °C) and combustion, were gathered, compared and ranked according to increasing temperature. A comprehensive model of thermal conversion as a function of temperature, pressure and heating rate of biomass has been provided. For the most important, basic process, which is pyrolysis, five mechanisms of thermal decomposition kinetics of its components (lignin, cellulose, hemicellulose) were presented. The most important apparatuses and implementing devices have been provided for all biomass conversion methods excluding combustion. The process of combustion, which is energy recycling, was omitted in this review of biomass thermal conversion methods for two reasons. Firstly, the range of knowledge on combustion is too extensive and there is not enough space in this study to fully discuss it. Secondly, the authors believe that combustion is not an environmentally-friendly method of waste biomass utilization, and, in the case of valuable biomass, it is downright harmful. Chemical compounds contained in biomass, such as biochar, oils and gases, should be recovered and reused instead of being simply burnt—this way, non-renewable fuel consumption can be reduced.
Thermal failure of a second rotor stage in heavy duty gas turbine
- Daniel Sławiński
- Paweł Ziółkowski
- Janusz Badur
2020 Pełny tekst ENGINEERING FAILURE ANALYSIS
The impulse mode of operation and the supply of various types of fuels causes frequent failures even in the heavy duty gas turbines. The paper presents the ravages of second rotor stage failure in a gas turbine. The excessive thermal elongation rise caused by fuel change was indicated as the main cause. We applied nonlinear numerical analysis, preceded by thermodynamic calculations of the turbine and visual inspection of the effects of failure. Simulations were performed on undamaged blade geometry under load resulting from combustion: nominal fuel and the changed fuel. Thermodynamic calculations demonstrated a 70 °C increase in temperature using the changed fuel. The blade tip displacements demonstrated the possibility of abrasion. The amount of displacement of the tip of the turbine blade with increasing pressure or increasing rotational speed do not pose as great a threat, as does the increase in the temperature. To maintain long-term and safe operation of a gas turbine, it is necessary to strictly observe the manufacturer's guidelines regarding fuel composition. If during the operation of a gas turbine it is likely that it can be powered by various types of fuels, then the structure should have adequate effort reserves and working tolerances.
Thermal Images Analysis Methods using Deep Learning Techniques for the Needs of Remote Medical Diagnostics
- Alicja Kwaśniewska
2020 Pełny tekst
Remote medical diagnostic solutions have recently gained more importance due to global demographic shifts and play a key role in evaluation of health status during epidemic. Contactless estimation of vital signs with image processing techniques is especially important since it allows for obtaining health status without the use of additional sensors. Thermography enables us to reveal additional details, imperceptible in images acquired with standard visible light cameras, yet, low resolution is its significant limitation. In the presented doctoral dissertation, original artificial intelligence solutions were proposed based on performed analysis of innovative thermal image processing methods using Deep Learning techniques for the needs of remote medical diagnostics. Possibility of modifying architecture of deep neural network designed for classification of visible light images in such a way that distribution of extracted features will be recreated enabling detection of facial areas from low resolution thermal data was verified in conducted experiments. Effectiveness of the proposed deep neural network architecture was demonstrated in practical applications, increasing resolution of thermal images and leading to better image quality metrics in comparison to stateof-the-art convolutional models, as well as increasing accuracy of facial areas detection, contactless estimation of respiratory rate and person recognition.
Thermally tuneable optical and electrochemical properties of Au-Cu nanomosaic formed over the host titanium dimples
- Wiktoria Lipińska
- Katarzyna Grochowska
- Jakub Karczewski
- Jacek Ryl
- Adam Cenian
- Siuzdak Katarzyna
2020 Pełny tekst CHEMICAL ENGINEERING JOURNAL
Au-Cu nanostructures offer unique optical and catalytic properties unlike the monometallic ones resulting from the specific interaction. Among others, they have the ability to exhibit surface plasmon resonance, electrochemical activity towards the oxygen and hydrogen evolution reaction (OER, HER) as well as improved photoresponse in relation to monometalic but those properties depend highly on the substrate where bimetallic structures are immobilized. In this work, bimetallic gold-copper mosaics over the conducting structured titanium substrate were fabricated via following steps: anodization of Ti foil, chemical etching of as-formed titania resulting in nanodimpled Ti substrate (TiND), sputtering of thin metal layer (Au, Cu) in various sequences, and finally thermal treatment in furnace at 450°C or 600°C. The morphology, optical and structural properties were investigated in details and it was shown that both arrangements of metallic films and thermal conditions strongly affect the morphology and optical features. The XPS results confirmed the presence of gold-copper alloys and copper oxide species. Last but not least, the electrochemical activities were verified in 0.1 M NaOH using cyclic voltammetry and linear voltammetry measurements performed in dark and under visible light illumination. Among all investigated materials in both anodic and cathodic regimes bimetallic 5Au/5Cu sample annealed at 450°C exhibits the highest response towards OER and HER, respectively. This is further boosted by the light with λ>420 nm. Upon exposure to visible light, the current density for 5Au/5Cu and 5Cu/5Au electrodes reached 1.32 mA cm-2 and 1.26 mA cm-2, respectively, while in the case of monometallic structures the current was below 10 μA cm-2. Both optical and electrochemical behaviour indicate a strong synergistic effect arising within the bimetallic mosaic formed over the TiND.
Thermal-Resistant Polyurethane/Nanoclay Powder Coatings: Degradation Kinetics Study
- Maryam Jouyandeh
- Behzad Hadavand
- Farimah Tikhani
- Reza Khalili
- Babak Bagheri
- Payam Zarrintaj
- Krzysztof Formela
- Henri Vahabi
- Mohammad Saeb
2020 Pełny tekst Coatings
In the present study, thermal degradation kinetics of polyurethane (PU) powder coatings reinforced with organo-modified montmorillonite (OMMT) was investigated. PU nanocomposites were prepared in different concentrations of 1, 3, and 5 wt.% of OMMT via the extrusion method. The microstructure of the nanocomposites was observed by scanning electron microscope (SEM) illustrating uniform dispersion of OMMT nano-clay platelets in the PU matrix except for the sample containing 5 wt.% nano-palates. Thermal degradation kinetics of the PU nanocomposite was investigated using thermogravimetric analysis (TGA) at different heating rates of 5, 10, and 20 °C/min. The results showed that the initial decomposition temperatures were shifted toward higher values (more than 40 °C for T5% and up to 20 °C for T10%) by introducing the nano-clay to the PU matrix. Friedman, Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and modified Coats-Redfern iso-conversional methods were applied to model the decomposition reaction and the activation energy of the nanocomposite powder coatings. Overall, the presence of nano-clay increased the activation energy of the PU degradation up to 45 kJ/mol, when compared to the blank PU, which suggests very high thermal stability of nanocomposites. The Sestak-Berggren approach proposed a good approximation for the reaction model, especially at low temperatures. Thus, PU decomposition was detected as an autocatalytic reaction, which was suppressed by the barrier effect of OMMT nano-palates intercalated with polymer chains.
Thermochemical Conversion of Biomass and Municipal Waste into Useful Energy Using Advanced HiTAG/HiTSG Technology
- Jan Stąsiek
- Marek Szkodo
2020 Pełny tekst ENERGIES
An advanced thermal conversion system involving high-temperature gasification of biomass and municipal waste into biofuel, syngas or hydrogen-rich gas is presented in this paper. The decomposition of solid biomass and wastes by gasification is carried out experimentally with a modern and innovative regenerator and updraft continuous gasifier, among others. A ceramic high-cycle regenerator provides extra energy for the thermal conversion of biomass or any other solids waste. Highly preheated air and steam gas (heated up to 1600 C) was used as an oxidizing or gasification agent (feed gas). Preheated feed gas also enhances the thermal decomposition of the gasification solids for fuel gas. However, the main objective of this work is to promote new and advanced technology for the thermochemical conversion of biomass for alternative energy production. Selected results from experimental and numerical studies are also presented.
Thermodynamic study of binary mixtures of toluene with ionic liquids, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide
- Dorota Warmińska
- Iwona Cichowska-Kopczyńska
2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS
Densities, refractive indices and viscosities at 293.15, 298.15, 303.15, 308.15 and 313.15 K of binary mixtures of toluene with 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide have been measured over the miscible region at p = 0.1 MPa. From the experimental data, values of excess molar volume, excess thermal expansion, deviation in refractive index, deviation in viscosity and excess Gibbs energy of activation for viscous flow have been calculated. These properties have been fitted to the Redlich-Kister-type polynomial equation in order to analyse non-ideal behaviour of the studied mixtures. Moreover, partial and apparent molar volumes of toluene and ionic liquid in their binary systems have been calculated. Finally, the effects of temperature and cation of ionic liquid on the physicochemical properties were analysed and discussed in terms of intermolecular interactions occurring in the studied systems.
Thermohydraulic maldistribution reduction in mini heat exchangers
- Paweł Dąbrowski
2020 Pełny tekst APPLIED THERMAL ENGINEERING
A detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm × 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave manifolds in Z-type flow configuration. The working medium was ethanol and the mass flow rate was 5 × 10−4 kg/s. Both sections were heated from the bottom side. Heat flux of 10 000 W/m2 and 5000 W/m2 was applied to the minichannel and minigap section respectively. The method of the flow maldistribution mitigation in the diabatic flow has been checked. Thanks to introducing a threshold, the maldistribution coefficient can be reduced about twice in the minigap section or three times in the minichannel section with the 0.5 mm threshold as compared to the conventional arrangement. The velocity profile and temperature profile over the heat exchanger’s surface have been analyzed. Reduction of the maldistribution results in lower maximum temperature over the surface. The distribution is more uniform in the minichannel section than in the minigap section. This is due to a two-dimensional flow over a minigap. Hence, a two-dimensional approach to define maldistribution coefficients in minigap sections, which has not been distinguished in literature yet was used.
Thermophysical study of the binary mixtures of triethyl phosphate with N-methylformamide, N,N-dimethylformamide and N,N-dimethylacetamide – Experimental and theoretical approach
- Dorota Warmińska
- Maciej Śmiechowski
2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS
Densities at (293.15, 298.15, 303.15 and 308.15) K, and viscosities and ultrasonic velocities at 298.15 K of binary liquid mixtures of triethyl phosphate with N-methylformamide, N,N-dimethylformamide and N,N-dimethylacetamide have been measured over the entire range of composition at p = 0.1 MPa. From the experimental data, values of excess molar volume, excess isentropic compressibility, viscosity deviation and excess Gibbs energy of activation for viscous flow have been calculated. These results were fitted to the Redlich-Kister-type polynomial equation. The viscosity deviations and the excess Gibbs energy were found to be positive for the all systems investigated, while the excess volumes and the excess isentropic compressibilities were negative for TEP + DMA and for TEP + DMF systems, and positive for mixtures TEP + NMF. These results were interpreted based on the strength of the specific interaction, size and shape of molecules. Molecular dynamics simulations were used to provide a detailed explanation of the differences between the TEP + NMF and other systems, which were ultimately traced to strong hydrogen bonding between NMF and TEP.
Thickness accuracy of sash gang sawing
- Kazimierz Orłowski
- Jakub Sandak
- Daniel Chuchała
2020 Pełny tekst BIORESOURCES
Thin lamellae, corresponding to the layer components of structural glued members, i.e. 2-ply or 3-ply glued parquet, can be manufactured in re-sawing operations of kiln-dried wood blocks. These must be prepared with high dimensional accuracy and adequate surface quality following specific technical requirements for lamellae thickness variations, especially in the upper layers of the glued composite parquet. The accuracy of oak lamellae thickness was examined here for a re-sawing process performed on the sash gang saw. A series of cutting tests were carried out in sawmill production conditions. The overall objective for these observations was to determine an effect of both the cumulative time of sawing (progress of the tool wear) and the lamella position (distribution of lateral forces) on the dimensional accuracy of production. Lamellae size control was conducted following the Brown methodology. Detailed within-board, between-board, and total sawing standard deviations for the examined lamellae positions in the gang were determined. The obtained results revealed that outermost lamellae are more subjected to dimensional inaccuracy than lamellae from the centre of the sawn block or frieze
Three-dimensional printed trachea helps to design tailored treatment for tracheobronchomalacia
- Robert Dziedzic
- Gustaw Rzyman
- Witold Rzyman
2020 Pełny tekst Polish Archives of Internal Medicine
Tracheobronchomalacia is a rare respiratory disease that is manifesting by impaired ventilation with expiratory collapse of the tracheal wall due to softening of the supporting cartilage and hypotonia of myoelastic elements [1]. Surgery is the mainstay of treatment. We report the case of 39 -year old man with exacerbation of chronic respiratory distress. The membranous wall of the trachea and the large bronchi was stretched to such an extent that the tracheal lumen was almost completely closed during the exhalation phase, and the cartilage bent in the opposite direction taking the opposite C-shape. To plan the operation in detail, we used 3D printing. We made the airway model in 3d using the GE AW-suite software. Then the model was printed on a 3d printer in plastic. The tracheobronchoplasty through right posterolateral thoracotomy was performed. A polipropylen mesh was sewn into the membranous wall of the trachea and main bronchi. A satisfactory wallresult was obtained. 3D printed trachea was very helpful in the planning of the operational strategy.
Tight bounds on global edge and complete alliances in trees
- Kacper Wereszko
- Robert Kozakiewicz
- Robert Lewoń
- Michał Małafiejski
2020
In the talk the authors present some tight upper bounds on global edge alliance number and global complete alliance number of trees. Moreover, we present our NP-completeness results from [8] for global edge alliances and global complete alliances on subcubic bipartite graphs without pendant vertices. We discuss also polynomial time exact algorithms for finding the minimum global edge alliance on trees [7] and complete alliance on trees [8].
TIM
- Luciano Segreto
2020
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Time Domain Modeling of Propeller Forces due to Ventilation in Static and Dynamic Conditions
- Anna Kozłowska
2020 Pełny tekst Journal of Marine Science and Engineering
This paper presents experimental and theoretical studies on the dynamic effect on the propeller loading due to ventilation by using a simulation model that generates a time domain solution for propeller forces in varying operational conditions. For ventilation modeling, the simulation model applies a formula based on the idea that the change in lift coefficient due to ventilation computes the change in the thrust coefficient. It is discussed how dynamic effects, like hysteresis effects and blade frequency dynamics, can be included in the simulation model. Simulation model validation was completed by comparison with CFD (computational fluid dynamics) calculations and model experiments. Experiments were performed for static and dynamic (heave motion) conditions in the large towing tank at the SINTEF Ocean in Trondheim and in the Marine Cybernetics Laboratories at NTNU (Norwegian University of Science and Technology). The main focus of this paper is to explain and validate the prediction model for thrust loss due to ventilation and out of water effects in static and dynamic heave conditions.
TiO2-based magnetic nanocomposites with core-shell structure
- Zuzanna Bielan
2020 Pełny tekst
The main aim of the doctoral dissertation was preparation and characterization of photocatalysts, with particular emphasis on modified titanium (IV) oxide photocatalysts, which can be applied for the degradation of organic pollutants not susceptible to biodegradation. A particularly important aspect of the work was the development of preparation method of nanocomposites with the magnetic core-shell and photocatalyst shell (TiO2) structure, photocatalytic active under UV/Vis radiation. The use of the microemulsion method for the preparation of magnetic nanocomposites allowed for the creation of the desired structure, in which the core of the nanocomposite was iron (II) diiron (III), (Fe3O4), covered with a layer of inert silica and TiO2 photocatalyst. The second scientific aspect of the work was to increase the photocatalytic activity of the obtained nanocomposites in UV/Vis light and visible light by modifying the titanium(IV) oxide surface with platinum and copper, as well as introducing titanium defects into the crystal structure of TiO2. The obtained nanocomposites were used for the effective degradation of persistent organic pollutants present in flowback water after the hydraulic fracturing process and carbamazepine, a commonly used antiepileptic drug, classified as a pharmaceutical pollutant of the aquatic environment.