2021 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2021

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Model obliczania kosztu cyklu życia obiektu na przykładzie budynku mieszkalnego jednorodzinnego
- Adam Kristowski
- Beata Grzyl
- Marcin Szczepański
- Anna Jakubczyk-Gałczyńska
2021 Przegląd Budowlany
W artykule przedstawiono model obliczania kosztu cyklu życia budynku mieszkalnego jednorodzinnego oraz wskazano możliwości ograniczenia wydatków związanych z jego użytkowaniem w okresie trzydziestu lat. Celem prezentowanej analizy rachunku kosztu cyklu życia jest porównanie i ocena kosztów nabycia i użytkowania domu realizowanego według alternatywnych technologii z uwzględnieniem przyjętych rozwiązań w zakresie pozyskania energii, wykorzystanych materiałów, systemów grzewczych i wentylacji. Otrzymane rezultaty wskazują na korzyści płynące z wykorzystania w praktyce algorytmu przedstawionego w artykule.
Model-Based Adaptive Machine Learning Approach in Concrete Mix Design
- Patryk Ziółkowski
- Maciej Niedostatkiewicz
- Shao-Bo Kang
2021 Full text Materials
Concrete mix design is one of the most critical issues in concrete technology. This process aims to create a concrete mix which helps deliver concrete with desired features and quality. Contemporary requirements for concrete concern not only its structural properties, but also increasingly its production process and environmental friendliness, forcing concrete producers to use both chemically and technologically complex concrete mixtures. The concrete mix design methods currently used in engineering practice are joint analytical and laboratory procedures derived from the Three Equation Method and do not perform well enough for the needs of modern concrete technology. This often causes difficulties in predicting the final properties of the designed mix and leads to precautionary oversizing of concrete properties for fear of not providing the required parameters. A new approach that would make it possible to predict the newly designed concrete mix properties is highly desirable. The answer to this challenge can be methods based on machine learning, which have been intensively developed in recent years, especially in predicting concrete compressive strength. Machine learning-based methods have been more or less successful in predicting concrete compressive strength, but they do not reflect well the variability that characterises the currently used concrete mixes. A new adaptive solution that allows estimating concrete compressive strength on the basis of the concrete mix main ingredient composition by including two observations for a given batch of concrete is proposed herein. In presented study, a machine learning model was built with a deep neural network architecture, trained on an extensive database of concrete recipes, and translated into a mathematical formula. Testing on four concrete mix recipes was performed, which were calculated according to contemporary design methods (Bolomey and Fuller method), and a comparative analysis was conducted. It was found out that the new algorithm performs significantly better than that without adaptive features trained on the same dataset. The presented algorithm can be used as a concrete strength checking tool for the concrete mix design process.
Modeling an Industrial Revolution: How to Manage Large-Scale, Complex IoT Ecosystems?
- Geza Kulcsar
- Pal Varga
- Marek Tatara
- Federico Montori
- Michel A. Inigo
- Gianvito Urgese
- Paolo Azzoni
2021 Full text
Advancements around the modern digital industry gave birth to a number of closely interrelated concepts: in the age of the Internet of Things (IoT), System of Systems (SoS), Cyber-Physical Systems (CPS), Digital Twins and the fourth industrial revolution, everything revolves around the issue of designing well-understood, sound and secure complex systems while providing maximum flexibility, autonomy and dynamics. The aim of the paper is to present a concise overview of a comprehensive conceptual framework for integrated modeling and management of industrial IoT architectures, supported by actual evidence from the Arrowhead Tools project; in particular, we adopt a three-dimensional projection of our complex engineering space, from modeling the engineering process to SoS design and deployment. In particular, we start from modeling principles of the the engineering process itself. Then, we present a design-time SoS representation along with a toolchain concept aiding SoS design and deployment. This brings us to reasoning about what potential workflows are thinkable for specifying comprehensive toolchains along with their data exchange interfaces. We also discuss the potential of aligning our vision with RAMI4.0, as well as the utilization perspectives for real-life engineering use-cases.
Modeling and Evaluation of Electric Treeing Phenomena in Polymeric Cable Insulation
- Qasim Khan
- Shady S. Refaat
- Haitham Abu-Rub
- Hamid Toliyat
- Marek Olesz
2021
This paper investigates the treeing phenomenon in polymeric materials such as crosslinked polyethylene (XLPE) that is widely used in medium and high voltage power cables as primary insulation. The modeling of electrical tree growth in the insulation from its initiation to breakdown is significant research work that illustrates the discharge dynamics and its impact on aging process in polymeric insulation. This study utilizes pulse sequence analysis (PSA) mapping and phase-resolved partial discharge (PRPD) pattern to model the tree growth and its correlation with the aging in the XLPE samples. The applied electric stress magnitude as a crucial treeing aspect is utilized to comprehend treeing and its relationship with insulation degradation. The tree mapping and plots exemplify and characterize treeing stages to work as a reliable diagnostic tool to determine aging in solid insulation.
Modeling of Electrified Transportation Systems Featuring Multiple Vehicles and Complex Power Supply Layout
- Aleksander Jakubowski
- Leszek Jarzębowicz
- Mikołaj Bartłomiejczyk
- Jacek Skibicki
- Sławomir Judek
- Andrzej Wilk
- Mateusz Płonka
2021 Full text ENERGIES
The paper proposes a novel approach to modeling electrified transportation systems. The proposed solution reflects the mechanical dynamics of vehicles as well as the distribution and losses of electric supply. Moreover, energy conversion losses between the mechanical and electrical subsystems and their bilateral influences are included. Such a complete model makes it possible to replicate, e.g., the impact of voltage drops on vehicle acceleration or the necessity of partial disposal of regenerative braking energy due to temporary lack of power transmission capability. The modeling methodology uses a flexible twin data-bus structure, which poses no limitation on the number of vehicles and enables modeling complex traction power supply structures. The proposed solution is suitable for various electrified transportation systems including suburban and urban systems. The modeling methodology is applicable i.a. to Matlab/Simulink, which makes it broadly available and customizable, and provides short computation time. The applicability and accuracy of the method were verified by comparing simulation and measurement results on an exemplary trolleybus system operating in Pilsen, Czech Republic. Simulation of daily operation of an area including four supply sections and maximal simultaneous number of nine vehicles showed a good conformance with the measured data, with the difference in the total consumed energy not exceeding 5%.
Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators
- Jan Stąsiek
- Adam Stąsiek
- Marek Szkodo
2021 Full text ENERGIES
The main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal thermal and flow parameters requires the knowledge of the theory of heat exchangers as well as measurement methods and numerical calculations. Bearing in mind the above, the liquid crystal techniques (LCT), particle image velocimetry (PIV) and digital image processing (DIP) for temperature, velocity, friction factor and heat transfer coefficient measurements are presented herein. These three optical tools (using desktop computers) create an extremely powerful and advanced measuring technique that has not been available anywhere before. Brief histories of these measurement methods and techniques are discussed and some examples are presented. In order to assess and select the value of the measurement technique, local and average distributions of Nusselt numbers (in the measurement section) obtained by the transit analysis method on the inter-rib regions of a plate coated by thermochromics liquid crystal and heated by air as an alternative to the steady-state analysis. In the parallel, numerical calculation was performed with the use of the ANSYS Fluent software code and supported by laser anemometrycomputed turbulence intensity of air flow. Comparison of the Nusselt number distributions was determined by three methods, i.e., steady state, the transient method and CFD simulation. Up to three-fold enhancement of the local heat transfer capability was observed. Failure to take into account the surface of the ribs in heat transfer causes differences in the obtained results of the Nusselt number depending on the method used. Apart from the heat transfer data, the pressure drop in the form of friction factors is also presented. On the basis of the conducted research, it can be stated that both qualitative and quantitative coherence was obtained between the experimental and computational studies.
Modeling protein structures with the coarse-grained UNRES force field in the CASP14 experiment
- Anna Antoniak
- Iga Biskupek
- Krzysztof K. Bojarski
- Cezary Czaplewski
- Artur Giełdoń
- Mateusz Kogut
- Małgorzata M. Kogut
- Paweł Krupa
- Agnieszka Lipska
- Adam Liwo
- Emilia Lubecka
- Mateusz Marcisz
- Martyna Maszota-Zieleniak
- Sergey A. Samsonov
- Adam K. Sieradzan
- Magdalena J. Ślusarz
- Rafał Ślusarz
- Patryk A. Wesołowski
- Karolina Ziȩba
2021 Full text JOURNAL OF MOLECULAR GRAPHICS & MODELLING
The UNited RESidue (UNRES) force field was tested in the 14th Community Wide Experiment on the Critical Assessment of Techniques for Protein Structure Prediction (CASP14), in which larger oligomeric and multimeric targets were present compared to previous editions. Three prediction modes were tested (i) ab initio (the UNRES group), (ii) contact-assisted (the UNRES- contact group), and (iii) template-assisted (the UNRES-template group). For most of the targets, the contact restraints were derived from the server models top-ranked by the DeepQA method, while the DNCON2 method was used for 11 targets. Our consensus- fragment procedure was used to run template-assisted predictions. Each group also processed the Nuclear Magnetic Resonance (NMR)- and Small Angle X-Ray Scattering (SAXS)-data assisted targets. The average Global Distance Test Total Score (GDT TS) of the ‘Model 1’ predictions were 29.17, 39.32, and 56.37 for the UNRES, UNRES-contact, and UNRES-template predictions, respectively, increasing by 0.53, 2.24, and 3.76, respectively, compared to CASP13. It was also found that the GDT TS of the UNRES models obtained in ab initio mode and in the contact-assisted mode decreases with the square root of chain length, while the exponent in this relationship is 0.20 for the UNRES-template group models and 0.11 for the best performing AlphaFold2 models, which suggests that incorporation of database information, which stems from protein evolution, brings in long-range correlations, thus enabling the correction of force-field inaccuracies.
Modeling SARS‐CoV‐2 proteins in the CASP‐commons experiment
- Andriy Kryshtafovych
- John Moult
- Wendy M. Billings
- Dennis Della Corte
- Krzysztof Fidelis
- Sohee Kwon
- Kliment Olechnovič
- Chaok Seok
- Česlovas Venclovas
- Jonghun Won
- Alphafold Team
- Badri Adhikari
- Recep Adiyaman
- Joaquim Aguirre-plans
- Ivan Anishchenko
- Minkyung Baek
- David Baker
- Frederico Baldassarre
- Jacob Barger
- Sutanu Bhattacharya
- Debswapna Bhattacharya
- Mor Bitton
- Renzhi Cao
- Jianlin Cheng
- Charles Christoffer
- Cezary Czaplewski
- Zongyang Du
- Arne Elofsson
- Eshel Faraggi
- Michael Feig
- Narcis Fernandez-fuentes
- Nick Grishin
- Sergei Grudinin
- Zhiye Guo
- Yuya Hanazono
- Demis Hassabis
- Bryce Hedelius
- Lim Heo
- Naozumi Hiranuma
- Cassandra Hunt
- Ilia Igashov
- Takashi Ishida
- Robert L. Jernigan
- David Jones
- John Jumper
- Maria Kadukova
- Shaun Kandathil
- Chen Keasar
- Daisuke Kihara
- Lisa Kinch
- Yasuomi Kiyota
- Andrzej Kloczkowski
- Pushmeet Kohli
- Mateusz Kogut
- Elodie Laine
- Cade Lilley
- Jian Liu
- Adam Liwo
- Emilia Lubecka
- Arup Mondal
- Connor J. Morris
- Liam Mcguffin
- Alexis Molina
- Tsukasa Nakamura
- Baldo Oliva
- Alberto Perez
- Gabriele Pozzati
- Daipayan Sarkar
- Rin Sato
- Torsten Schwede
- Bikash Shrestha
- Tomer Sidi
- Gabriel Studer
- Md Hossain Shuvo
- Mayuko Takeda-shitaka
- Yuma Takei
- Genki Terashi
- Kentaro Tomii
- Yuko Tsuchiya
- Kathryn Tunyasuvunakool
- Bjorn Wallner
- Tianqi Wu
- Jinbo Xu
- Yu Yamamori
- Jianyi Yang
- Lisha Ye
- Chengxin Zhang
- Yang Zhang
- Wei Zheng
2021 PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS
Critical Assessment of Structure Prediction (CASP) is an organization aimed at advancing the state of the art in computing protein structure from sequence. In the spring of 2020, CASP launched a community project to compute the structures of the most structurally challenging proteins coded for in the SARS-CoV-2 genome. Forty-seven research groups submitted over 3000 three-dimensional models and 700 sets of accuracy estimates on 10 proteins. The resulting models were released to the public. CASP community members also worked together to provide estimates of local and global accuracy and identify structure-based domain boundaries for some proteins. Subsequently, two of these structures (ORF3a and ORF8) have been solved experimentally, allowing assessment of both model quality and the accuracy estimates. Models from the AlphaFold2 group were found to have good agreement with the experimental structures, with main chain GDT_TS accuracy scores ranging from 63 (a correct topology) to 87 (competitive with experiment).
Modelling AOB-NOB competition in shortcut nitrification compared with conventional nitrification-denitrification process
- Jakub Drewnowski
- Mehdi Sharifshourjeh
- Przemysław Kowal
- W Cel
2021 Full text Journal of Physics : Conference Series
In particular, mainstream deammonification and/or shortened nitrificationdenitrification via nitrite (so-called “nitrite shunt”) is a promising new treatment concept that has the potential to revolutionise how nitrogen removal is achieved at WWTPs. Understanding the role of the AOB/NOB competition in the nitrogen cycle in wastewater treatment systems will change operational strategies of the novel nitrogen removal processes. The key role in this process is inhibition of NOB activity undesirably affects AOB activity and leads to inefficient partial nitrification process and when used as pre-treatment for Anammox it can limit nitrite supply to Anammox bacteria. Successful NOB repression requires a combination of such factors as a low DO concentration, a rapid transition from aerobic to anoxic conditions, and tight control of Temperature and/or pH. The major driving force behind the successful NOB washout is the inhibition of those bacteria based on the difference in the growth rate between AOB and NOB. The obtained results from this study show the mechanisms and operating conditions (e.g. DO concentration, Temp.) leading to complete domination of AOB over NOB under aerobic conditions. This paper presents the perspectives on modelling AOB-NOB competition in shortcut nitrification. The combined deammonification, shortened nitrification-denitrification and/or nitritation-anammox process was compared with conventional nitrification-denitrification based on own experiments and literature data. Its successful application as shortcut nitrification technology and new control system will represent a paradigm shift for the wastewater industry, offering the opportunity for sustainable wastewater treatment, energy-neutral or even energypositive facilities, and substantial reductions in treatment costs.
Modelling Long‐Term Transition from Coal‐Reliant to Low‐Emission Power Grid and District Heating Systems in Poland
- Marcin Jaskólski
- Paweł Bućko
2021 Full text ENERGIES
Energy systems require technological changes towards climate neutrality. In Poland, where the power system is dominated by outdated coal-fired power plants, efforts to minimize the environmental impact are associated with high costs. Therefore, optimal paths for the development of the energy sector should be sought in order to achieve ambitious long-term strategic goals, while minimizing the negative impact on the consumers’ home budget. A methodology and a model for the development of the electricity and heat generation structure were developed and implemented in market allocation (MARKAL) modelling framework. Two scenarios were presented, i.e., business as usual (BAU) and withdrawal from coal (WFC) scenarios. The calculations showed a significant role of nuclear energy and offshore wind power in the pursuit of climate neutrality of electricity generation. In the BAU scenario, the model proposes to stay with coal technologies using carbon capture and storage systems. Withdrawal from coal (WFC scenario) makes it necessary to replace them by gas-fired power plants with CO2 sequestration. Solar energy can be used both in electricity and district heating. In order to build on the latter technological option, appropriate energy storage techniques must be developed. Geothermal energy is expected to be the key option for district heat generation in the long-term horizon. The proposed development paths guarantee a significant reduction in greenhouse gases and industrial emissions. However, complete climate neutrality is uncertain, given the current degree and dynamics of technological development.
Modelling of dark fermentation of glucose and sour cabbage
- Gaweł Sołowski
- Krzysztof Pastuszak
2021 Full text Heliyon
In the article, modified Anaerobic Digestion Models 1 (ADM-1) was tested for modelling dark fermentation for hydrogen production. The model refitting was done with the Euler method. The new model was based on sets of differential equations. The model was checked for hydrogen production from sour cabbage in batch and semi-batch in 5 g VSS (volatile solid suspension)/L and at the semi-batch process from glucose at 5 and 10 g VSS/L. Added parameters determined the conversion of a substrate, hydrogen production, and stress parameters. In the case of a semi-batch process, for one month, cumulative hydrogen production from sour cabbage of 5 g VSS/L was 0.9 L of cumulative hydrogen volume and from glucose 5 g VSS/L (in case of feeding 2 g VSS/L every two days) 2.5 L of cumulative hydrogen volume. At the bacterial population level, hydrogen production was a continuous process at an adequate range of population size and environmental parameters
Modelling of full-scale silo experiments with flow correcting inserts using material point method (MPM) based on hypoplasticity.
- Jakub Krzyżanowski
- Andrzej Tejchman-Konarzewski
- Michał Wójcik
2021 POWDER TECHNOLOGY
Charakterystyki przepływu materiałów sypkich w silosach mają znaczenie dla naporów wywieranych na ściany silosu. Można je zmieniać za pomocą różnych wkładek. W pracy omówiono wyniki liczbowe dotyczące ograniczonego przepływu niespoistego ziarnistego piasku w pełnowymiarowym silosie metalowym z różnymi symetrycznie rozmieszczonymi wkładami, służącymi do korekcji wzorca przepływu (podwójny stożek, stożek w stożku i odwrócony stożek). Do symulacji dynamicznego przepływu piasku w silosie zastosowano metodę punktu materialnego (MPM). Do opisu zachowania płynięcia piasku niespoistego przyjęto hipoplastyczny model konstytutywny. Nacisk położono na schematy przepływu i napory na ściany i wkładki silosu. Wyniki liczbowe zostały bezpośrednio porównane z odpowiednimi eksperymentami w silosie pełnowymiarowym. Osiągnięto zadowalającą zgodność wyników liczbowych i eksperymentalnych. W obliczeniach MPM zbadano również wpływ początkowego współczynnika porowatości piasku, kąta tarcia ściany silosu, położenia wkładki silosowej i rozmiaru komórek siatki MPM.
Modelling of shear zones during quasi-static granular silo flow using material point method (MPM)
- Jakub Krzyżanowski
- Andrzej Tejchman-Konarzewski
- Wojciech Sołowski
- Michał Wójcik
2021 Full text POWDER TECHNOLOGY
The paper focuses on confined silo flow of cohesionless sand. The problem considered is a quasi-static flow in a plane strain model silo with parallel walls simulated with the material point method (MPM). The simulation used a non-local hypoplastic constitutive model. Initially, the paper validated the implemented numerical approach with basic element tests and a plane strain compression test. The subsequent MPM calculations for a model silo were performed with different initial void ratios of sand and silo wall roughness. The flow simulations took also into account the different both location and width of the outlet. The emphasis was on the evolution of both shear zones (wall and internal curvilinear shear zones) and their impact on wall stresses/forces during flow. The numerical findings enhance the understanding of shear localization in granular materials during confined controlled flow in silos and its immense effect on the magnitude and distribution of wall pressures.
MODERNIZACJA DYDAKTYCZNEGO STANOWISKA LABORATORYJNEGO UMOŻLIWIAJĄCEGO ANALIZĘ PORÓWNAWCZĄ SPRAWNOŚCI ŚRUB NAPĘDOWYCH JACHTU MOTOROWEGO
- Piotr Bzura
2021 Full text Journal of Polish CIMEEAC
W artykule przedstawiono autorską metodę wyznaczania sprawności działania różnych śrub napędowych jachtu motorowego na podstawie wyników badań wykonanych na zmodernizowanym stanowisku laboratoryjnym. Modernizacja stanowiska składającego się ze źródła mocy w postaci silnika elektrycznego, części pośredniczącej i pędnika polegała na dodaniu przetwornika częstotliwości umożliwiającego starowanie silnikiem elektrycznym, czujnika do pomiaru prędkości wody względem pędnika i zanurzenia pędnika (śruby napędowej) w kanale przepływowym. Na podstawie analizy przeprowadzonych badań został przedstawiony algorytm, według którego porównano dwie różne śruby napędowe.
Modification of cellulosic filler with diisocyanates – volatile organic compounds emission assessment and stability of chemical structure over time
- Aleksander Hejna
- Mariusz Marć
- Jerzy Korol
2021 Full text NORDIC PULP & PAPER RESEARCH JOURNAL
This paper investigated the impact of type and content of diisocyanate on the structure of modified cellulose fillers. Four the most popular isocyanates were applied – isophorone, hexamethylene, toluene and methylene diphenyl diisocyanate – at loadings of 1–15 wt%. Chemical structure, and its short-term storage stability, were investigated for eight weeks. Moreover, the main volatile organic compounds detected during modification, as well as emitted from fillers before and after storage, were identified. The main compounds detected in the air during modifications were terpenes and terpenoids. No diisocyanates were detected, which is very beneficial considering their toxicity. They were emitted from modified fillers at 40 °C, but only from fresh samples. After storage no emissions were noted, which indicated successful modification of fillers, also confirmed by FTIR spectroscopy and changes in polarity of fillers’ surface. Observed changes should be considered beneficial for the potential applications of modified fillers in manufacturing of polymer composites.
Modification of structured bio‑carbon derived from spongin-based scaffolds with nickel compounds to produce a functional catalyst for reduction and oxidation reactions: Potential for use in environmental protection
- Sonia Żółtowska
- Zuzanna Bielan
- Joanna Zembrzuska
- Katarzyna Siwińska-Ciesielczyk
- Adam Piasecki
- Anna Zielińska-Jurek
- Teofil Jesionowski
2021 Full text SCIENCE OF THE TOTAL ENVIRONMENT
Three different 3D fibrous-like NiO/Ni(OH)2/Ni‑carbonized spongin-based materials were prepared via a simple sorption–reduction method. Depending on the support used, the catalysts were composed of carbon, nickel oxide, nickel hydroxide and zero-valent nickel, with the surface content of the nickel-containing phase in the range 15.2–26.0 wt%. Catalytic studies showed promising activity in the oxidation of phenolic compounds in water and in the reduction of 4-nitrophenol. The oxidation efficiency depends on the substrate used and ranges from 80% for phenol at pH 2 to 99% for 4-chlorophenoxyacetic acid (4-CPA) and methylchlorophenoxypropionic acid (MCPP). In the reduction reaction, all catalysts exhibited superior activity, with rate constants in the range 0.648–1.022 min-1. The work also includes a detailed investigation of reusability and kinetic studies.
Modified Inductive Multi-Coil Wireless Power Transfer Approach Based On Z-Source Network
- Bohdan Pakhaliuk
- Oleksandr Husev
- Viktor Shevchenko
- Janis Zakis
- Maksym Khomenko
- Ryszard Strzelecki
2021 Full text IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
This article presents a non-conventional approach to a multi-coil wireless power transfer system based on a Z-source network. The novelty of the approach lies in the use of a Z-source as a voltage source for energy transmission through the wireless power transfer coils. The main advantage is in a reduced number of semiconductors. This paper provides the design approach, simulation and experimental study. Feasibility and possible application fields are presented in the conclusions.
Modified SPWM Technique with Zero-Sequence Voltage Injection for a Five-Phase, Three-Level NPC Inverter
- Charles Odeh
- Dmytro Kondratenko
- Arkadiusz Lewicki
- Andrzej Jąderko
2021 Full text ENERGIES
This article presents a modified sinusoidal pulse-width modulation (SPWM) scheme for a five-phase, three-level neutral-point-clamped inverter. The modulation scheme deploys a modified min–max function to inject the zero-sequence components into the reference modulating signals; hence enabling the effective utilization of the DC-link voltage. Balanced split-input DC-link voltages were achieved through further incorporation of adjustable voltage-dependent variables into the reference signals. The dynamic performance of the control approach is demonstrated through simulations and experiments on a laboratory inverter prototype; the results are well presented.
Modular Approach for Modelling Warming Up Process in Water Installations with Flow-Regulating Elements
- Jacek Kropiwnicki
- Mariusz Furmanek
- Andrzej Rogala
2021 Full text ENERGIES
The paper presents a new method for modelling the warming up process of a water system with elements regulating the flow in a stochastic manner. The paper presents the basic equations describing the work of typical elements which the water installation is composed of. In the proposed method, a new computational algorithm was used in the form of an iterative procedure enabling the use of boundary conditions that can be stochastically modified during the warming-up process. A typical situation, when such a modification is processed, is the regulation of the medium flow through two-way or three-way valves or applying additional heat source. Moreover, the presented method does not require the transformation of the differential equations, describing the operation of individual elements, into a linear form, which significantly facilitates analytical work and makes it more flexible. The example of analysis of the operation of water installation used for controlling temperature of the process gases in a chemical installation shows the functionality and flexibility of the method. The adopted calculation schematics enable changing the direction of the heat flow while the heat exchanger is in operation. Additionally, the sequence of calculation processed in modules describing operation of installation elements is elective (there is no situation that output parameters from one element are used as input parameters for other element in the same calculation step).
Modyfikacja cementu kostnego w celu uzyskania długotrwałej ochrony antybakteryjnej
- Marcin Wekwejt
2021
Niniejsza rozprawa doktorska stanowi przewodnik po jednotematycznym cyklu publikacji, dotyczącym modyfikacji akrylowego cementu kostnego celem uzyskania długotrwałej i efektywnej ochrony antybakteryjnej. W ramach niego przeprowadzono badania eksperymentalne polegające na opracowaniu technologii wytwarzania modyfikowanego cementu kostnego oraz procedury medycznej jego stosowania. Cement kostny był modyfikowany przez zastosowanie trzech typów dodatków w różnych stężeniach: antybakteryjnych (nanocząstek srebra, miedzi lub ich kombinacji), biodegradowalnych (celuloza, chitozan, trójfosforan wapnia, polidioksanon i magnez) oraz bioaktywnych (bioszkło 45S5 i 1393-B3). W badaniach oceniano zależność między składem cementu, zwłaszcza rodzajami i stężeniami dodatków, a jego właściwościami fizyczno-chemicznymi, mechanicznymi oraz biologicznymi. Uzyskane wyniki pozwoliły na dobór optymalnego składu chemicznego cementu kompozytowego, w którym dodatek nanosrebra wynosi 1,5% mas., zaś bioaktywnego szkła 5,0 % mas. W zależności od medycznego przeznaczenia, domieszkowany nanosrebrem cement zawierający bioszkło 45S5 zaleca się do zastosowań jako substytut kości z profilaktyczną osłoną antybakteryjną, natomiast cement wzbogacony bioszkłem 1393-B3 do zastosowań terapeutycznych w celu zwalczenia infekcji. Opracowane cementy pozwalają znacząco eliminować problemy związane ze stosowaniem dotychczasowych cementów w praktyce klinicznej.