2021 - Repozytorium publikacji - Politechnika Gdańska

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Optimization of thermal backfill configurations for desired high-voltage power cables ampacity
- Stanisław Czapp
- Filip Ratkowski
2021 Pełny tekst ENERGIES
The ampacity of high-voltage power cables depends, among others, on their core cross-sectional area as well as thermal resistivity of the thermal backfill surrounding the cables. The cross-sectional area of the power cables’ core is selected according to the expected power to be transferred via the cable system. Usually, the higher the power transfer required, the higher the cross-sectional area of the core. However, the cost of high-voltage power cables is relatively high and strictly depends on the dimensions of the core. Therefore, from the economic point of view, it is interesting to focus on the improvement of the thermal condition around the cables, by changing the dimension of the thermal backfill, instead of increasing the power cables’ core cross-sectional area. In practice, it is important to find the optimal dimensions of both cable core and thermal backfill to achieve the economically attractive solution of the power cable transfer system. This paper presents a mathematical approach to the power-cable system design, which enables selecting the cost-optimal cross-section of a power cable core depending on the dimensions of the thermal backfill. The proposal herein allows us to indicate the condition in which it is advantageous to increase the core cross-sectional area or to expand the dimension of the backfill. In this approach, the optimal backfill geometry can also be evaluated. The investment costs of the 110 kV power cable system with the core cross-sectional areas consecutively equal to 630, 800 and 1000 mm2 have been compared.
Optimization of Train Energy Cooperation Using Scheduled Service Time Reserve
- Michał Urbaniak
- Ewa Kardas-Cinal
2021 Pełny tekst ENERGIES
The main aim of the paper was to develop an innovative approach to the preliminary estimation possibility of train energy cooperation based on data from timetables, without traction calculations. The article points out the need to strive for sustainable and environmentally friendly transport. It was pointed out that rail transport using electric traction is one of the more ecological branches of transport. It also offers a number of possibilities for improving energy efficiency and reducing energy consumption, one of which is the recovery and reuse of energy lost in the electrodynamic braking process. The main ways in which such energy can be used are listed, but the focus is mainly on the aspect of the so-called “energy cooperation” of trains. Then, the current state of the research and knowledge on the narrowed scope of rail traffic management and recuperative braking in rail transportation is presented; an innovative approach to the indirect optimization of the amount of recuperated electrical energy immediately usable by another vehicle by maximizing the duration of energy co-optimization is proposed; and the authors’ function is proposed to enable optimization, taking into account various parameters. The optimization was performed with the use of a proprietary, multi-criteria objective function and the Solver optimization module. Finally, the results obtained using the proposed approach are presented and illustrated with the example of train timetables used by some of the largest railway stations in Poland.
Optimization-based antenna miniaturization using adaptively-adjusted penalty factors
- Marzieh Mahrokh
- Sławomir Kozieł
2021 Pełny tekst Electronics
The continuing trend for miniaturization of electronic devices necessitates size reduction of the comprising components and circuitry. Specifically, integrated circuit-antenna modules therein require compact radiators in applications such as 5G communications, implantable and on-body devices, or internet of things (IoT). The conflict between the demands for compact size and elec-trical and field performance can be mitigated by means of constrained numerical optimization. Evaluation of performance-related constraints requires expensive electromagnetic (EM) analysis of the system at hand, therefore their explicit handling is inconvenient. A workaround is the penalty function approach where the primary objective (typically, antenna size) is complement-ed by additional terms quantifying possible constraint violations. The penalty coefficients that determine contributions of these terms, are normally adjusted manually, which hinders precise control over antenna performance figures and often leads to inferior results in terms of achieved miniaturization rates. This paper proposes a novel algorithm featuring an automated adjust-ment of the penalty factors throughout the optimization process. Our methodology is validated using three broadband antenna structures. The obtained results demonstrate that the presented adaptive adjustment permits a precise control over the constraint violations while leading to better miniaturization rates as compared to manual penalty term setup.
Optimizing FSO networks resilient to adverse weather conditions by means of enhanced uncertainty sets
- Ilya Kalesnikau
- Marinela Shehaj
- Dritan Nace
- Michał Pióro
2021 Optical Switching and Networking
This work deals with dimensioning of wireless mesh networks (WMN) composed of FSO (free space optics) links. Although FSO links realize broadband transmission at low cost, their drawback is sensitivity to adverse weather conditions causing transmission degradation on multiple links. Hence, designing such FSO networks requires an optimization model to find the cheapest configuration of link capacities that will be able to carry an acceptable level of the demanded traffic in all weather states that can be foreseen in network operation. Such a model can be achieved using robust optimization techniques, and for that it is important to find a tractable way of characterizing possible link (capacity) degradation states corresponding to weather conditions not known in advance. In the paper we show how the set of link degradation states may be represented mathematically in a compact and tractable way to be exploited in optimization. To solve this task we will make use of a generalization of a combinatorial problem of finding a minimum hitting set to deduce a compact set approximating a given set of link degradation states, (called uncertainty set). Finally, we provide a mathematical model with respect to a general form of uncertainty sets and illustrate the effectiveness of our model by means of a numerical study.
Organic syntheses greenness assessment with multicriteria decision analysis
- Marek Tobiszewski
- Witold Przychodzeń
- Marta Bystrzanowska
- Maria Milewska
2021 Pełny tekst GREEN CHEMISTRY
Green chemistry requires a metrics system that is comprehensive by the criteria included and simple in the application at the same time. We propose the application of multicriteria decision analysis for com- parative greenness assessment of organic synthesis procedures. The assessment is based on 9 criteria (the reagent, reaction efficiency, atom economy, temperature, pressure, synthesis time, solvent, catalyst and reactant) for which data points are easily extractable from synthesis protocols. The criteria are given weights by two experts to differentiate their relative importance. Two datasets are created, one of the pro- cedures for benzoic acid synthesis, the second one of procedures for γ-valerolactone synthesis. In both cases, the greenest procedure is identified and the remaining ones are ranked according to their green- ness. The proposed assessment procedure incorporates more assessment criteria than product/waster ratio mass-based metric and is much less tedious than the application of life-cycle assessment.
Otwarte innowacje w polskich małych i średnich przedsiębiorstwach
- Natalia Przybylska
2021
Niniejsza monografia poświęcona jest analizie związku między działalnością innowacyjną małych i średnich przedsiębiorstw a otwartymi innowacjami. Publikacja wpisuje się w szeroki nurt badań empirycznych nad otwartymi innowacjami oraz stanowi uzupełnienie luki poznawczej dotyczącej badania zależności między wykorzystaniem OI a aktywnością innowacyjną polskich małych i średnich przedsiębiorstw. Badania empiryczne, których fragment zaprezentowano w monografii, zostały przeprowadzone w 2015 roku na reprezentatywnej próbie małych i średnich przedsiębiorstw w Polsce.
Otwarte zasoby edukacyjne - przegląd inicjatyw w Polsce i na świecie
- Kamila Kokot-Kanikuła
- Anna Wałek
2021 Pełny tekst e-mentor
Otwarte zasoby edukacyjne (OZE) to materiały szkoleniowe oraz narzędzia wspierające zarówno uczenie, jak i nauczanie. Zjawisko to nierozerwalnie łączy się z szerszym pojęciem otwartej edukacji (OE), które postuluje zniesienie barier w nauczaniu tak, aby uczący się mogli zdobywać wiedzę zgodnie ze swoimi potrzebami edukacyjno-szkoleniowymi. Celem artykułu jest zapoznanie czytelników z zagadnieniem otwartych zasobów edukacyjnych, prezentacja kluczowych dla ich powstania i rozwoju podstaw prawnych i organizacyjnych oraz przedstawienie najnowszych inicjatyw podejmowanych w zakresie upowszechniania OZE. W pierwszej części artykułu wyjaśnione zostały pojęcia oraz rola otwartych zasobów edukacyjnych w procesie nauczania, a następnie zaprezentowane wybrane inicjatywy realizowane przez członków European Network of Open Education Librarians (ENOEL), a także wyniki ankiety przeprowadzonej wśród pracowników europejskich bibliotek akademickich przez organizację SPARC Europe. Analiza piśmiennictwa, treści dokumentów prawnych, raportów i rekomendacji pozwoliła na precyzyjne określenie znaczenia otwartych zasobów edukacyjnych dla ich użytkowników. Wieloaspektowość działań oraz ich skala potwierdzają, że nowoczesne nauczanie może rozwijać się szybciej w oparciu o otwarte materiały edukacyjne.
Oxidation step in the preparation of benzocamalexin: The crystallographic evidence
- Yordan Stremski
- Anife Ahmedova
- Anna Dołęga
- Stela Statkova-Abeghe
- Desislava Kirkova
2021 MENDELEEV COMMUNICATIONS
The study of oxidation step in the preparation of benzocamalexin by the α-amidoalkylation–oxidation sequence revealed the formation of perchloro-1,2-phenylene dibenzoate as the product of transformation of tetrachloro- 1,2-benzoquinone applied as the oxidant. The structures of benzocamalexin and perchloro-1,2-phenylene dibenzoate were confirmed by X-ray diffraction analysis. The extraction step in the final isolation of benzocamalexin is supposed to be crucial for the complete transformation of mono- and di- acylated perchloropyrocatechol.
Palm Oil Fuel Ash-Based Eco-Efficient Concrete: A Critical Review of the Short-Term Properties
- Mugahed Amran
- G. Murali
- Roman Fediuk
- Nikolai Vatin
- Yuriy Vasilev
- Hakim Abdelgader
2021 Pełny tekst Materials
The huge demand for concrete is predicted to upsurge due to rapid construction developments. Environmental worries regarding the large amounts of carbon dioxide emanations from cement production have resulted in new ideas to develop supplemental cementing materials, aiming to decrease the cement volume required for making concrete. Palm-oil-fuel-ash (POFA) is an industrial byproduct derived from palm oil waste’s incineration in power plants’ electricity generation. POFA has high pozzolanic characteristics. It is highly reactive and exhibits satisfactory micro-filling ability and unique properties. POFA is commonly used as a partially-alternated binder to Portland cement materials to make POFA-based eco-efficient concrete to build building using a green material. This paper presents a review of the material source, chemical composition, clean production and short-term properties of POFA. A review of related literature provides comprehensive insights into the potential application of POFA-based eco-efficient concrete in the construction industry today.
Paradoks decyzyjny – racjonalne i intuicyjne podejmowanie decyzji
- Henryk Krawczyk
2021
W pracy scharakteryzowano poszczególne etapy działań prowadzące do znajdowania najlepszych rozwiązań dla rozpatrywanego problemu. Zwrócono uwagę na paradoks decyzyjny który wskazuje, że mądre rozwiązanie problemu wymaga zarówno racjonalnego, jak i intuicyjnego podejścia. Na przykładzie sortowania obrazów zaprezentowano niezależnie oba podejścia podkreślając potrzebę ich wzajemnego uzupełniania się. Podkreślono trudność budowy algorytmów, które będą uwzględniać jednocześnie te dwa odmienne podejścia. Prowadzi to do znalezienia rozwiązań nieoptymalnych, ale satysfakcjonujących wszystkich zainteresowanych. Pozwoli też na stopniowe wyjaśnianie ludzkiej mądrości i jej roli przy rozwiązywaniu życiowych problemów.
PARAMETRIC ANALYSIS OF THE EFFICIENCY OF THE COMBINED GAS-STEAM TURBINE UNIT OF A HYBRID CYCLE FOR THE FPSO VESSEL
- Serhiy Serbin
- Nikolay Washchilenko
- Marek Dzida
- Jerzy Kowalski
2021 Pełny tekst Polish Maritime Research
A thermal diagram of the combined gas‒steam turbine unit of a hybrid cycle, which is an energy complex consisting of a base gas turbine engine with a steam turbine heat recovery circuit and a steam-injected gas turbine operating with overexpansion, is proposed. A mathematical model of a power plant has been developed, taking into consideration the features of thermodynamic processes of simple, binary, and steam-injected gas‒steam cycles. Thermodynamic investigations and optimization of the parameters of a combined installation of a hybrid cycle for the generation of electrical energy have been carried out. Three-dimensional calculations of the combustion chamber of a steam-injected gas turbine were carried out, which confirmed the low emissions of the main toxic components.
Parseval Wavelet Frames on Riemannian Manifold
- Marcin Bownik
- Karol Dziedziul
- Anna Kamont
2021 Pełny tekst JOURNAL OF GEOMETRIC ANALYSIS
We construct Parseval wavelet frames in L 2 (M) for a general Riemannian manifold M and we show the existence of wavelet unconditional frames in L p (M) for 1 < p < ∞. This is made possible thanks to smooth orthogonal projection decomposition of the identity operator on L 2 (M), which was recently proven by Bownik et al. (Potential Anal 54:41–94, 2021). We also show a characterization of Triebel–Lizorkin F sp,q (M) and Besov B sp,q (M) spaces on compact manifolds in terms of magnitudes of coefficients of Parseval wavelet frames. We achieve this by showing that Hestenes operators are bounded on F sp,q (M) and B sp,q (M) spaces on manifolds M with bounded geometry.
Partial inhibition of borohydride hydrolysis using porous activated carbon as an effective method to improve the electrocatalytic activity of the DBFC anode
- Małgorzata Graś
- Łukasz Kolanowski
- Zhijie Chen
- Katarzyna Lota
- Kacper Jurak
- Jacek Ryl
- Bing-Jie Ni
- Grzegorz Lota
2021 Sustainable Energy & Fuels
Carbon materials are commonly used catalyst supports in various types of fuel cells. Due to the possibility of designing their properties, they seem to be attractive and functional additives. In Direct Borohydride Fuel Cells (DBFCs), the electrooxidation reaction of borohydride competes with the undesirable hydrolysis reaction, therefore our work aimed to modify anodes based on a multi-component hydrogen storage alloy with a small number of activated carbons obtained from coffee waste to improve the hydrogen electrosorption properties. The produced activated carbons differed in terms of their physicochemical properties due to the different coffee waste-to-KOH ratio (1 : 1–1 : 4). Pressure measurements confirmed their effectiveness in relation to unconsumed hydrogen release, which initially hindered fuel diffusion. Nevertheless, it has been established that the addition of activated carbons improved the electrocatalytic activity of the anode, especially during cyclic operation (coulombic efficiency increased from 23% to 44% of the theoretical value). Moreover, X-ray photoelectron spectroscopy revealed that borohydride as a known reducing agent caused the reduction of oxygen functional groups on the carbon surface during DBFC operation, which made it possible to eliminate one of the factors influencing the BOR characteristics, and thus a more precise comparison of the analyzed activated carbons.
PAYMENT TRANSACTIONS’ ENERGY EFFICIENCY
- Tetiana Osadcha
- Oleksandr Melnychenko
2021 Pełny tekst Współpraca Europejska
The payment system and infrastructure is a sector that is not given enough attention today in the context of energy efficiency. This sector plays a big role in organizing and ensuring money circulation and funds. It has its value consisting on the one hand of the cost of payment equipment, infrastructure, payment instruments. On other hand, its value consists of the cost of energy for their manufacture and maintenance. The European Commission has proposed raising the target for reducing greenhouse gas emissions, including emissions and removals, to at least 55% by 2030 compared to 1990. The EU's ambitions to improve energy efficiency can be enhanced either by improving the energy efficiency of each sector or by improving some sectors more than others. And there are thousands upon thousands of areas in which energy efficiency can and should be improved: from matchmaking to, in fact, payment transactions. The payment system and money circulation seem to be not the biggest problems in the energy sector. However, this is a very delicate topic, because often people pay in supermarkets the money earned, buying food and basic necessities. They spend their energy in vain, waiting in line for a payment transaction. Modern means of payment and payment methods do not address the problem of reducing the time for servicing payments, which entails the overuse of time, energy, and money. And the latest method of payment using cryptocurrencies can not change the situation for the better today. The use of new and advanced technologies such as new generation data transmission systems, the use of modern computers' computing power, the replacement of means of payment with "faster" ones, the use of more efficient cashiers, or their replacement by functional machines can reduce these indicators.
Perfect thermal contact of hyperbolic conduction semispaces with an interfacial heat source
- Oleksii Nosko
2021 Pełny tekst INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
The problem of thermal contact between two bodies with a heat source at their interface presents great scientific and practical interest. On the time scale of a nanosecond or shorter, heat propagation should be considered in the form of thermal waves of finite speeds. This study investigated the thermal behaviour of hyperbolic conduction semispaces in perfect thermal contact subjected to the action of an interfacial heat source. An analytical solution was derived using the Laplace integral transform approach. The contact temperature and heat fluxes were analysed for different ratios of thermal conductivities K 1 and K 2 , thermal diffusivities k 1 and k 2 , and thermal relaxation times τ1 and τ2 of the semispaces. It was shown that the interfacial heat generation results in a step-wise change in the contact temperature. It was also found that the initial partition of heat between the semispaces occurs due to the ratio of K 1 / k 1 τ1 and K 2 / k 2 τ2 . The applicability of the obtained solution and its particular expressions was illustrated on the example of microscopic problems of ultra-short laser pulse welding and sliding friction.
Performance and Emission Modelling and Simulation of Marine Diesel Engines using Publicly Available Engine Data
- Mohammad Ghaemi
2021 Pełny tekst Polish Maritime Research
To analyse the behaviour of marine diesel engines in unsteady states for different purposes, for example to determine the fuel consumption or emissions level, to adjust the control strategy, to manage the maintenance, etc., a goal-based mathematical model that can be easily implemented for simulation is necessary. Such a model usually requires a wide range of operating data, measured on a test stand. This is a time-consuming process with high costs and the relevant data are not available publicly for a selected engine. The present paper delivers a rapid and relatively simple method for preparing a simulation model of a given marine diesel engine, based only on the widely available data in the project guides indicated for steady state conditions. After establishing the framework of the mathematical model, it describes how the parameters of the model can be adjusted for the simulation model and how the results can be verified as well. Conceptually, this is a trial and error method, but the presented case example makes clear how the parameters can be selected to reduce the number of trials and quickly determine the model parameters. The necessary descriptions are given through a case study, which is the MAN-B&W 8S65ME-C8 marine diesel engine. The engine is assumed to be connected to a constant pitch propeller. The presented mathematical model is a mean-value zero-dimensional type with seven state variables. The other variables of the engine are determined based on the state independent variables and the input value, which is the fuel rate. The paper can be used as a guideline to prepare a convenient mathematical model for simulation, with the minimum publicly available data.
Performance Evaluation of GAM in Off-Body Path Loss Modelling for Body Area Networks
- Michał Laskowski
- Sławomir Ambroziak
- Luis M. Correia
- Krzysztof Świder
2021 Pełny tekst
This paper addresses the performance evaluation of an off-body path loss model, based on measurements at 2.45 GHz, which has been developed with the use of the Generalised Additive Model, allowing to model a non-linear dependence on different predictor variables. The model formulates path loss as a function of distance, antennas’ heights, antenna orientation angle and polarisation, results showing that performance is very sensitive to the orientation angle and to the polarisation of the transmitting and receiving antennas. Considering the model’s global performance, the obtained overall value of the adjusted coefficient of determination equals 0.60, while the mean error and the root mean square error equal 0 dB and 5.6 dB, respectively, which can be considered quite good for such a large diversity of addressed scenarios. One can then conclude that, regardless of the low performance of the method for some particular cases, the overall model accuracy may be considered good.
Performance Models of a Multidomain IMS/NGN Service Stratum
- Sylwester Kaczmarek
- Maciej Sac
2021
This paper quantifies call processing performance (CPP) of a multidomain IMS/NGN architecture, which was proposed to deliver current and future telecommunication services with strict quality requirements, independently of the transport network technologies. A realistic simulation model is used as a reference for evaluation of the analytical results, in which vari-ous types of queuing systems are applied to model the opera-tion of servers and links in a multidomain IMS/NGN. The compared results include mean Call Set-up Delay (E(CSD)) and mean Call Disengagement Delay (E(CDD)), a subset of standardized CPP parameters, which are very important for satisfaction of users and must be taken into account during network design. As a result, complete recommendations on queuing systems for a design process of a multidomain IMS/NGN are presented, given both accuracy and computation complexity.
Performance of a new commercial high-definition 3D patient specific quality assurance system for CyberKnife robotic radiotherapy and radiosurgery
- Md Abdullah Al Kafi
- Akram Al Moussa
- Mohd Fahmi Mohd Yousof
- Marek J. Maryański
- Belal Moftah
2021 RADIATION MEASUREMENTS
Conventional two dimensional and low-definition measurement techniques for dosimetric verification of radiotherapy treatment deliveries are no longer adequate in the era of hypofractionation and extremely high dose gradients. New quality assurance (QA) tools with 3D capability and high definition are urgently needed. The purpose of this study was to evaluate the performance of one of the first such commercial systems as applied to CyberKnife (CK) radiotherapy/radiosurgery system. This study employed the recently developed commercial 3D patient-specific quality assurance (PSQA) system. Tissue-equivalent radiochromic polymer gel dosimeters, sealed in light protective thin-wall glass spheres (CrystalBalls), were mounted in a high-precision acrylic QA stand. Patient treatment plans were superimposed on the simulator CT scan of one selected CrystalBall and were irradiated in CK machine. CrystalBalls were then scanned using a laser CT scanner (OCTOPUS, MGS Research, Inc., DBA 3D Dosimetry, Madison, CT, USA). The simulator CT scan and the laser CT scan of the CrystalBall were registered in 6D using the VOLQA (MGS Research, Inc., DBA 3D Dosimetry, Madison, CT, USA) software. Planned and delivered dose distributions were compared by means of 3D gamma passing rates at user-selected acceptance criteria. Cumulative 3D dose-volume histograms and overlays of orthogonal profiles and isodoses both in 2D and in 3D were also generated, along with voxel statistics for dose difference and distance-to-agreement criteria. Twelve stereotactic radiosurgery/stereotactic radiotherapy/stereotactic body radiation therapy patients were selected randomly such that each set of two represented one of the six diagnoses: brain metastasis, trigeminal neuralgia, spine metastasis, prostate cancer, lung cancer and liver cancer. [...] The 3D gamma passing rate averaged over all patients studied was (90.5 ± 6.7) % at acceptance criteria of 2% (local) dose difference and 2 mm distance-to-agreement down to 20% isodose. For 3% (local) dose difference and 3 mm distance-to-agreement (also down to 20% cutoff dose), the average passing rate was (96.0 ± 3.1) %. The results of the study presented here form part of the information needed to assess suitability of a system and hence, the results suggest that the new high-definition 3D CrystalBall system can be a useful PSQA tool as a part of quality assurance for CK.
Performance of acicular grindable thermocouples for temperature measurements at sliding contacts
- Oleksii Nosko
- Wojciech Tarasiuk
- Yurii Tsybrii
- Andrey Nosko
- Adolfo Senatore
- Veronica D'Urso
2021 Pełny tekst MEASUREMENT
The present study investigates the performance of acicular grindable thermocouples based on a constantan wire / steel hollow cylinder construction. The experiments showed that the measuring junction electrical resistance, temperature–voltage characteristic, measuring junction rise time and signal noise standard deviation of the acicular thermocouples are comparable to those of conventional J-type thermocouples with bare wire diameter 0.25–0.5 mm. A pin-on-disc tribometer study of brake friction materials revealed that the acicular thermocouple involved in friction indicates up to 30% higher temperature than the contact temperature rise measured by infrared thermography. Another finding is that the infrared thermography contact temperature can be predicted with significantly higher accuracy by combining the acicular and conventional thermocouple techniques and taking the weighted sum of the respective temperatures.