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  • Optimization of Data Assignment for Parallel Processing in a Hybrid Heterogeneous Environment Using Integer Linear Programming
    • Tomasz Boiński
    • Paweł Czarnul
    2021 Pełny tekst COMPUTER JOURNAL

    In the paper we investigate a practical approach to application of integer linear programming for optimization of data assignment to compute units in a multi-level heterogeneous environment with various compute devices, including CPUs, GPUs and Intel Xeon Phis. The model considers an application that processes a large number of data chunks in parallel on various compute units and takes into account computations, communication including bandwidths and latencies, partitioning, merging, initialization, overhead for computational kernel launch and cleanup. We show that theoretical results from our model are close to real results as differences do not exceed 5% for larger data sizes, with up to 16.7% for smaller data sizes. For an exemplary workload based on solving systems of equations of various sizes with various compute-to-communication ratios we demonstrate that using an integer linear programming solver (lp_solve) with timeouts allows to obtain significantly better total (solver+application) run times than runs without timeouts, also significantly better than arbitrary chosen ones. We show that OpenCL 1.2’s device fission allows to obtain better performance in heterogeneous CPU+GPU environments compared to the GPU-only and the default CPU+GPU configuration, where a whole device is assigned for computations leaving no resources for GPU management.

  • Optimization of the Aeration Strategies in a Deammonification Sequencing Batch Reactor for Efficient Nitrogen Removal and Mitigation of N2O Production
    • Hussein Al-Hazmi
    • Lu Xi
    • Joanna Majtacz
    • Przemysław Kowal
    • Li Xie
    • Jacek Mąkinia
    2021 Pełny tekst ENVIRONMENTAL SCIENCE & TECHNOLOGY

    In deammonification systems, nitrite-oxidizing bacteria (NOB) suppression and nitrous oxide (N2O) mitigation are two important operational objectives. To carry out this multivariable analysis of response, a comprehensive model for the N cycle was developed and evaluated against experimental data from a laboratory-scale deammonification granular sludge sequencing batch reactor. Different aeration strategies were tested, and the manipulated variables comprised the dissolved oxygen (DO) set point in the aerated phase, aeration on/off frequency (F), and the ratio (R) between the non-aerated and aerated phase durations. Experimental results showed that a high ammonium utilization rate (AUR) in relation to the low nitrate production rate (NPR) (NPR/AUR = 0.07−0.08) and limited N2O emissions (EN2O < 2%) could be achieved at the DO set point = 0.7 mg O2/L, R ratio = 2, and F frequency = 6−7 h−1 . Under specific operational conditions (biomass concentration, NH4 + -N loading rate, and temperature), simulation results confirmed the feasible aeration strategies for the trade-offs between the NOB suppression and N2O emission. The intermittent aeration regimes led to frequent shifts in the predominating N2O production pathways, that is, hydroxylamine (NH2OH) oxidation (aerated phase) versus autotrophic denitrification (non-aerated phase). The inclusion of the extracellular polymeric substance mechanism in the model explained the observed activity of heterotrophs, especially Anaerolineae, and granule formation.

  • OPTIMIZATION OF THE LAST STAGE OF GAS-STEAM TURBINE USING A HYBRID METHOD
    • Paweł Ziółkowski
    • Łukasz Witanowski
    • Piotr Klonowicz
    • Stanisław Głuch
    2021

    This paper relates to the CFD calculation of a new turbine type which is in the phase of theoretical analysis, because the working fluid is a mixture of steam and gas generated in wet combustion chamber. At first, this article concentrates on a possibility of streamlining the flow efficiency of a last stage of axial turbine working on gas-steam mixture using a hybrid of the particle swarm optimization algorithm with the Nelder-Mead method called HNMPSO. Subsequently, this article aim is to redesign and analyze the flow characteristics of the last stage of the gas-steam turbine. Values of the maximized objective function, which is the isentropic efficiency of the turbine stage, are found from 3D RANS computation of the flowpath geometry changing during the improving scheme. Among the optimized variables are parameters characterising the shape of the endwall contours within the rotor domain.

  • Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements
    • Ewa Janicka
    • Michał Mielniczek
    • Łukasz Gaweł
    • Kazimierz Darowicki
    2021 Pełny tekst ENERGIES

    Water management is a key factor affecting the efficiency of proton exchange membrane fuel cells (PEMFCs). The currently used monitoring methods of PEMFCs provide limited information about which processes or components that humidity has a significant impact upon. Herein, we propose the use of a novel approach of impedance measurements using a multi-sinusoidal perturbation signal, which enables impedance measurements under dynamic operating conditions. The manuscript presents the effect of the relative humidity (RH) of the reactants on the instantaneous impedance of the middle cell in the PEMFC stack as a function of the current load. Analysis of changes in the values of equivalent circuit elements was carried out to determine which process determines the stack’s performance depending on the load range of the fuel cell during operation. Comprehensive impedance analysis showed that to ensure optimal cell operation, the humidity of the reactants should be adjusted depending on the load level. The results showed that at low-current loads, the humidity of gases should be at least 50%, while at high-current loads, the cell should operate optimally at a gas humidity of 30% or lower. The presented methodology provides an important tool for optimizing and monitoring the operation of fuel cells.

  • 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.

  • Performance of Passive and Active Balancing Systems of Lithium Batteries in Onerous Mine Environment
    • Wojciech Kurpiel
    • Przemysław Deja
    • Bartosz Polnik
    • Marcin Skóra
    • Bogdan Miedziński
    • Marcin Habrych
    • Grzegorz Debita
    • Monika Zamłyńska
    • Przemysław Falkowski-Gilski
    2021 Pełny tekst ENERGIES

    To use lithium-iron-phosphate battery packs in the supply systems of any electric mining equipment and/or machines, the required conditions of work safety must be met. This applies in particular to coal mines endangered by fire and/or explosion. To meet the spark-safety conditions, the cells (together with the battery management system—BMS) must be isolated from the influence of the environment, and therefore placed in special fire-tight housings. This significantly degrades the heat dissipation, thus affecting the operating conditions of the cell-packs. Therefore, their usage without the so-called BMS is not recommended, as shown in the authors’ preliminary research. In practice, various BMS are used, most often with the so-called passive balancing. However, their application in mines is uncertain, due to the effect of heating under operation. When it comes to active BMS, they usually possess a quite complex structure and hence, are relatively expensive. Therefore, the authors conducted research for two specially developed active and one commercial passive BMS cooperating with selected lithium-iron-phosphate (LiFePO4) batteries when used in a suspended mining vehicle type PCA-1. The tests were carried out under environmental temperatures ranging from +5 °C to +60 °C. The effect of mismatching (12.5% to 37.5% of total cells number) of the cell parameters on the temperature distribution and voltage fading at the terminals of individual cells was checked. As a result of the investigations, the practical usefulness of the developed active BMS was determined, enabling the extension of the lithium-iron-phosphate battery life under onerous mine conditions, for a single recharge, which is a novelty. On the basis of the obtained results, appropriate practical conclusions were formulated.

  • Persistent homology as a new method of the assessment of heart rate variability
    • Grzegorz Graff
    • Beata Graff
    • Paweł Pilarczyk
    • Grzegorz Jabłoński
    • Dariusz Gąsecki
    • Krzysztof Narkiewicz
    2021 Pełny tekst PLOS ONE

    Heart rate variability (hrv) is a physiological phenomenon of the variation in the length of the time interval between consecutive heartbeats. In many cases it could be an indicator of the development of pathological states. The classical approach to the analysis of hrv includes time domain methods and frequency domain methods. However, attempts are still being made to define new and more effective hrv assessment tools. Persistent homology is a novel data analysis tool developed in the recent decades that is rooted at algebraic topology. The Topological Data Analysis (TDA) approach focuses on examining the shape of the data in terms of connectedness and holes, and has recently proved to be very effective in various fields of research. In this paper we propose the use of persistent homology to the hrv analysis. We recall selected topological descriptors used in the literature and we introduce some new topological descriptors that reflect the specificity of hrv, and we discuss their relation to the standard hrv measures. In particular, we show that this novel approach provides a collection of indices that might be at least as useful as the classical parameters in differentiating between series of beat-to-beat intervals (RR-intervals) in healthy subjects and patients suffering from a stroke episode.

  • Pervaporation in food processing
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2021 Pełny tekst

    This chapter is about pervaporation in food processing

  • Pervaporation Zeolite-Based Composite Membranes for Solvent Separations
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2021 Pełny tekst MOLECULES

    Thanks to their well-defined molecular sieving and stability, zeolites have been proposed in selective membrane separations, such as gas separation and pervaporation. For instance, the incorporation of zeolites into polymer phases to generate composite (or mixed matrix) membranes revealed important advances in pervaporation. Therefore, the goal of this review is to compile and elucidate the latest advances (over the last 2-3 years) of zeolite applications in pervaporation membranes either combining zeolites or polymers. Here, particular emphasis has been focused on relevant insights and findings in using zeolites in pervaporative azeotropic separations and specific aided applications, together with novel concepts of membranes. A brief background of the pervaporation process is also given. According to the findings of this review, we provide future perspectives and recommendations for new researchers in the field.

  • Pharmaceuticals and another groups of emerging contaminants: Occurrence and sources in Admiralty Bay (King George Island, Maritime Antarctica)
    • Małgorzata Szopińska
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Joanna Potapowicz
    • Ola Svahn
    • Erland Bjorklund
    • Żaneta Polkowska
    2021

    Everyday live activities may introduce a wide range of chemicals into wastewater systems. In this study presence of selected types of pharmaceuticals from cardiovascular system group, nervous and muscolo-skeleton system group, antimicrobial agents, genitourinary and sex hormones were tested in the wastewater from H. Arctowski Antarctic station. Moreover, the receiver of discharged wastewater (Admiralty Bay) were also studied. Considering the construction of new station facilities in the nearest future, this study was undertaken to support the selection of proper wastewater management, which is crucial to mitigate the environmental impact of human activity. The dispersal and distribution of wastewater after discharge into the receiver was analysed in 2017 and 2019 using: pharmaceuticals and other emerging pollutants analysis. Total list of compounds is available in (Svahn and Björklund 2016). Pharmaceuticals were tested using UPLC-ESI-MS/MS. Results have shown the presence of pharmaceutical substances in wastewater including: diclofenac, naproxen, doxycillin, propanolol at the level of ng/L. Moreover, their trace amounts have also been identified in the receiver (marine costal water of Admiralty Bay). The presence of anti-inflammatory agents, antibiotics or beta-blockers in marine waters in the such e pristine environment like Antarctica can lead to long-term negative effects, which are not yet fully understood at this moment. Thus, considering high expectation for preserving Antarctic environment novel approaches for wastewater treatment should be considered (including zero discharge of pollutants (emerging contaminants and non-indigenous microorganisms), as well as potential reuse of treated water – as an important aspect of circular economy.

  • Phosphorus and nitrogen forms in liquid fraction of digestates from agricultural biogas plants
    • Agnieszka Tuszyńska
    • Anna Wilińska
    • Krzysztof Czerwionka
    2021 ENVIRONMENTAL TECHNOLOGY

    The novelty of the presented research is the determination of the nitrogen and phosphorus fraction in the liquid fraction of digestate from agricultural biogas plants. This information is important because it can help in proposing possible further liquid fraction management or developing of new technologies for their purification. The research covered digestates from agricultural biogas plants, obtained from the fermentation of three different groups of waste, i.e. agricultural lignocellulosic waste (where corn silage was a monosubstrate or a dominant co-substrate), food waste (where fruit and vegetable waste or distillery residue were monosubstrate or dominant cosubstrate) and livestock manure (where cow manure was a monosubstrate or a dominant cosubstrate). Concentrations of nutrients in the liquid fraction of digestates varied within a wide range (230.9–649.1 mg PO4 3−/L and 1363–3211 mg N/L), and their content was determined by the feedstock characteristic. The highest concentrations of organic phosphorus were found in the liquid fraction of digestates from the fermentation of distillery brew and livestock manure, and the lowest in the fermentation of fruit and vegetable waste. In the liquid fraction of digestates from agricultural biogas plants, regardless of the composition of the feedstock, the dominant nitrogen form was ammonium nitrogen (from 60% to 90% TN). Organic nitrogen was dominated by CON fraction, which was from 35% to 54% of ON. It was 1.3–1.6 times higher than the DON fraction

  • Phosphorus concentration and availability in raw organic waste and post fermentation products
    • Agnieszka Tuszyńska
    • Krzysztof Czerwionka
    • Hanna Obarska-Pempkowiak
    2021 JOURNAL OF ENVIRONMENTAL MANAGEMENT

    The aim of the study was to determine the mobility of phosphorus forms in raw organic waste and from the solid and liquid fractions of digestate. To achieve the purpose of this study, the components (including livestock manure, agricultural waste, food waste, sewage sludge) and their post fermentation products were considered. Subsequently, the effect of the fermentation process on the mobility of phosphorus forms in post-fermentation fractions (solid and liquid) was investigated. Then, the evaluation of the fertilising potential of digestate fractions was assessed. The available organic and inorganic phosphorus forms were determined according to the Standards in Measurements and Testing (SMT) Programme extraction protocol and according to the acid molybdate spectrophotometric method. It has been shown that phosphorus in digestates occurred mainly in inorganic forms with Fe, Al, Mn, Mg and Ca ions. Its proportion in relation to total phosphorus ranged from 80 to 90%. The lowest phosphorus content was found in digestate from the fermentation of agricultural and food waste (fruit and vegetables), while digestate from livestock manure and sewage sludge fermentation was rich in phosphorus. It was shown that the solid fractions of digestate represented from 30 to 70% of highly labile phosphorus (i.e. phosphorus with organic matter and in bonds with Al, Fe, Mg and Mn oxides and hydroxides) in relation to total phosphorus. However, the share of labile phosphorus forms in the liquid fraction of digestates was much higher and accounted for 80–90% of the total phosphorus.

  • Photogrammetry image-based approach for imperfect structure modelling and FE analysis
    • Krzysztof Wołoszyk
    • Paweł Bielski
    • Yordan Garbatov
    • Tomasz Mikulski
    2021 Pełny tekst OCEAN ENGINEERING

    This study aims to model and analyse imperfect tructures using real measurements, employing photogrammetry technique commonly used in the geodesy. The study highlights the capability of the photogrammetry in aiding the structural analysis of imperfect engineering objects. Firstly, the photogrammetry measurements of a stiffened plate are carried out using a specially designed for the purpose experimental stand. Then, the plate surface geometry and structural configuration are reconstructed using commercial software. The resulting cloud of points is transformed into a regular mesh with a controlled grid size using a specially developed algorithm. The geometry of a stiffened plate, with measured initial imperfections, is then transferred to a finite element model and analysed. The ultimate strength analysis of stiffened plates considering different imperfections modelling techniques is conducted. The results are compared with the one obtained for measured imperfections, and several conclusions are derived. The proposed methodology revealed to be cost-effective and can be applied in various branches of shipbuilding and ocean engineering.

  • Photoluminescence as a probe of phosphorene properties
    • Maciej R. Molas
    • Łukasz Macewicz
    • Aleksandra Wieloszyńska
    • Paweł Jakóbczyk
    • Andrzej Wysmołek
    • Robert Bogdanowicz
    • Jacek B. Jasinski
    2021 Pełny tekst npj 2D Materials and Applications

    Here, we provide a detailed evaluation of photoluminescence (PL) as a comprehensive tool for phosphorene characterization with the emphasis on a prominent quantitative role of PL in providing fingerprint-like features due to its extreme sensitivity to the band structure details, anisotropy, disorder, external fields, etc. Factors such as number of layers, dimensionality, structural and chemical disorder, and environmental factors and their effect on phosphorene’s PL signal are reviewed and discussed. Applications of PL in monitoring phosphorene and its modifications, as well as potential impacts on the fields of chemical and biosensing, nanomedicine, and solar energy harvesting, are also elaborated.

  • PHOTON LUMINESCENCE STUDIES OF TETRAHYDROFURAN FOLLOWING TRIHYDROGEN CATIONS IMPACT IN THE 20–1000 EV ENERGY RANGE
    • Tomasz Wąsowicz
    2021 Pełny tekst Romanian Reports in Physics

    Photon emission arising during tetrahydrofuran (C4H8O, THF) fragmentation initiated by H3 + ion impact has been studied experimentally. Luminescence fragmentation spectra and the relative emission cross-sections of the excited fragments have been measured using collision-induced emission spectroscopy in the 20–1000 eV energy range. The main features in the spectra are the H Balmer series lines, whose intensities decrease with increasing principal quantum number n more quickly than predicted by quantum theory. Optical spectra also display weak emission of vibrationally and rotationally excited diatomic CH fragments. The possible mechanisms leading to the observed products are discussed.

  • Photoresponsive Amide-Based Derivatives of Azobenzene-4,4′-Dicarboxylic Acid—Experimental and Theoretical Studies
    • Natalia Łukasik
    • Koleta Hemine
    • Iwona Anusiewicz
    • Piotr Skurski
    • Ewa Paluszkiewicz
    2021 Pełny tekst Materials

    Azobenzene derivatives are one of the most important molecular switches for biological and material science applications. Although these systems represent a well-known group of compounds, there remains a need to identify the factors influencing their photochemical properties in order to design azobenzene-based technologies in a rational way. In this contribution, we describe the synthesis and characterization of two novel amides (L1 and L2) containing photoresponsive azobenzene units. The photochemical properties of the obtained compounds were investigated in DMSO by UV-Vis spectrophotometry, as well as 1H NMR spectroscopy, and the obtained results were rationalized via Density Functional Theory (DFT) methods. After irradiation with UV light, both amides underwent trans to cis isomerization, yielding 40% and 22% of the cis isomer of L1 and L2 amides, respectively. Quantum yields of this process were determined as 6.19% and 2.79% for L1 and L2, respectively. The reverse reaction (i.e., cis to trans isomerization) could be achieved after thermal or visible light activation. The analysis of the theoretically determined equilibrium structure of the transition-state connecting cis and trans isomers on the reaction path indicated that the trans-cis interconversion is pursued via the flipping of the substituent, rather than its rotation around the N=N bond. The kinetics of thermal back-reaction and the effect of the presence of the selected ions on the half-life of the cis form were also investigated and discussed. In the case of L1, the presence of fluoride ions sped the thermal relaxation up, whereas the half-life time of cis-L2 was extended in the presence of tested ions.

  • Physics-Based Coarse-Grained Modeling in Bio- and Nanochemistry
    • Adam Liwo
    • Adam K. Sieradzan
    • Agnieszka S. Karczyńska
    • Emilia Lubecka
    • Sergey A. Samsonov
    • Cezary Czaplewski
    • Paweł Krupa
    • Magdalena Mozolewska
    2021

    Coarse-grained approaches, in which groups of atoms are represented by single interaction sites, are very important in biological and materials sciences because they enable us to cover the size- and time-scales by several orders of magnitude larger than those available all-atom simulations, while largely keeping the details of the systems studied. The coarse-grained approaches differ by the scheme of reduction and by the origin and parameterization of the respective force fields. Both statistical (database-derived) and physics-based potentials are used, the physics-based potentials enabling us to bridge the coarse-grained level with the all-atom level, which is necessary when carrying out the simulations at multiple resolutions (multiscale simulations). The physics-based potentials originate from the potential of mean force (PMF) of a system under study, in which the degrees of freedom that are not considered in the model are averaged out. For tractability and transferability the PMF has to be expressed as a sum of contributions that constitute the effective energy terms. These terms are often assigned analytical expressions imported from all-atom force fields or engineered to reproduce certain structural patterns (e.g., the secondary structures of proteins or nucleic acids). Tabulated (model-free) potentials are also applied. Approaches also exist in which the effective energy terms are derived systematically by splitting the potential of mean force into transferable terms, e.g., by expressing the PMF by the Kubo cluster-cumulant functions. Two approaches, or a combination thereof, are applied in the parameterization of the coarse-grained force fields: the bottom-up one, in which the potentials of mean force are determined from atomistically-detailed calculations and then used to parameterize the respective expressions, and the top-down approach, in which the force field is tuned to fit the experimental data. In this chapter, the theory and parameterization of the physics-based coarse-grained force fields, along with the corresponding methods of conformational search are reviewed. Examples of physics-based coarse-grained force fields applied to study biomolecules and their assemblies and nanosystems are discussed.

  • Physics-guided neural networks (PGNNs) to solve differential equations for spatial analysis
    • Bartłomiej Borzyszkowski
    • Karol Damaszke
    • Jakub Romankiewicz
    • Marcin Świniarski
    • Marek Moszyński
    2021 Pełny tekst Bulletin of the Polish Academy of Sciences-Technical Sciences

    Numerous examples of physically unjustified neural networks, despite satisfactory performance, generate contradictions with logic and lead to many inaccuracies in the final applications. One of the methods to justify the typical black-box model already at the training stage and lead to many inaccuracies in the final applications. One of the methods to justify the typical black-box model already at the training stage involves extending its cost function by a relationship directly inspired by the physical formula. This publication explains the concept of physics- involves extending its cost function by a relationship directly inspired by the physical formula. This publication explains the concept of Phys- guided neural network (PGNN), makes an overview of already proposed solutions in the field and describes possibilities of implementing ics-guided neural networks (PGNN), makes an overview of already proposed solutions in the field and describes possibilities of implementing physics-based loss functions for spatial analysis. Our approach shows that the model predictions are not only optimal but also scientifically physics-based loss functions for spatial analysis. Our approach shows that the model predictions are not only optimal but also scientifically consistent with domain specific equations. Furthermore, we present two applications of PGNNs and illustrate their advantages in theory by consistent with domain specific equations. Furthermore, we present two applications of PGNNs and illustrate their advantages in theory by solving Poisson’s and Burger’s partial differential equations. The proposed formulas describe various real-world processes and have numerous solving Poisson’s and Burger’s partial differential equations. The proposed formulas describe various real-world processes and have numerous applications in the area of applied mathematics. Eventually, the usage of scientific knowledge contained in the tailored cost functions shows that applications in the area of applied mathematics. Eventually, the usage of scientific knowledge contained in the tailored cost functions shows that our methods guarantee physics-consistent results as well as better generalizability of the model compared to classical, artificial neural networks. our methods guarantee physics-consistent results as well as better generalizability of the model compared to classical, artificial neural networks

  • Physiological Biomarkers Assessed by Low‐Tech Exercise Tests Predict Complications and Overall Survival in Patients Undergoing Pneumonectomy Due to Lung Cancer
    • Tomasz Marjanski
    • Damian Wnuk
    • Robert Dziedzic
    • Marcin Ostrowski
    • Wioletta Sawicka
    • Ewa Marjańska
    • Witold Rzyman
    2021 Pełny tekst Cancers

    Due to its debilitating character pneumonectomy this is last‐resort procedure. Preoperative results of the 6‐min walking test (6MWT) help to identify high risk of postoperative complications and increased mortality in patients undergoing lobectomy for lung cancer. The aim of the study was to validate the value of 500 m in 6MWT as an indicator, which differentiates risk of complications in patients undergoing pneumonectomy. 125 patients who underwent pneumonectomy at Thoracic Surgery Department between 2009 and 2018. On the day preceding the surgery, patients underwent 6MWT. The patients were in median age of 63 years. The cut‐off value of 500 m identified patients with increased 90‐day mortality [17.9% vs. 3.5%, odds ratio (OR) 6.271, 95% confidence interval (CI) 1.528–25.739], first‐year mortality (30.7% vs. 11.6%, OR 3.378, 95%CI 1.310–8.709), and overall survival (p = 0.02). Patients who covered a distance ≤ 500 m had an increased risk of atrial fibrillation (35.9% vs. 16.3%, OR 2.880, 95%CI 1.207–6.870) and cardiac complications (38.4% vs. 19.8%, OR 2.537, 95%CI 1.100–5.849). Patients unable to reach 500 m in 6MWT are in a high risk of postoperative death after pneumonectomy, what may be a result of increased frequency of postoperative cardiac complications. Poor result of 6MWT is a predictor of worse overall survival.

  • Pier of the future- investigation of green and blue strategies as tools for modernization of Gdynia's public waterfront
    • Dominik Sędzicki
    • Jarosław Bąkowski
    2021

    Between rising water levels and global migration to cities, architects and designers need to critically reimagine the relationship between coastal landscapes and public space. Cities are facing entirely new risks and environmental conditions. Resiliency, infrastructure, and ecology are increasingly common terms, reflecting the growing demand to address the spatial and formal challenges faced by cities worldwide. Rethinking boundaries and edges, designers have unique opportunities to help shape public understanding of these conditions through waterfront parks.

  • Pierwsza prezentacja obrazu na wystawie "Differentia specifica" w Galerii Feininger w Trzebiatowskim Ośrodku Kultury w Trzebiatowie w terminie 31 lipca do 31 sierpnia 2021. Obraz "Bez tytułu", technika akrylowa na papierze. Wymiary: 75 x 75 cm. Rok powstania: 2021.
    • Dominika Krechowicz
    2021

    Obraz "Bez tytułu", technika akrylowa na papierze. Wymiary: 75 x 75 cm. Rok powstania: 2021

  • Pin Angle Thermal Effects on Friction Stir Welding of AA5058 Aluminum Alloy: CFD Simulation and Experimental Validation
    • Supat Chupradit
    • Dmitry Olegovich Bokov
    • Wanich Suksatan
    • Michał Landowski
    • Dariusz Fydrych
    • Mahmoud E. Abdullah
    • Hesamoddin Aghajani Derazkola
    2021 Pełny tekst Materials

    The friction stir welding (FSW) of tool pin geometry plays a critical role in the final properties of the produced joint. The tool pin geometry directly affects the generation of heat and the flow of internal materials during the FSW process. The effects of the FSW tool pin angle on heat generation and internal flow have not been quantitatively investigated in detail. In this manuscript, a validated Computational Fluid Dynamic (CFD) model was implemented to analyze the effects of pin angle on the thermo-mechanical action during the FSW process of AA5058 Al-Mg alloy. Experimental test results validate the thermal outcomes of the used model. The obtained results revealed that, when the pin angle is increased, the heat generation decreases while the mechanical action of the tool increases. The internal heat distribution at a higher pin angle is symmetrical. The higher mechanical action of the tool decreases the viscosity of the internal materials and increases stirring action (materials flow) around the pin. Furthermore, plastic flow near the tool increased stirring action and formed a larger stir zone in the joint area.

  • Planning optimised multi-tasking operations under the capability for parallel machining
    • Mieczysław Siemiątkowski
    • Mariusz Deja
    2021 Pełny tekst JOURNAL OF MANUFACTURING SYSTEMS

    The advent of advanced multi-tasking machines (MTMs) in the metalworking industry has provided the opportunity for more efficient parallel machining as compared to traditional sequential processing. It entailed the need for developing appropriate reasoning schemes for efficient process planning to take advantage of machining capabilities inherent in these machines. This paper addresses an adequate methodical approach for a non-linear process planning with a variety of alternatives, enabled through the STEP_NC standard. A relevant algorithmic approach of high efficacy is developed for feature clustering and operation sequencing based on AND-OR graph modelling. It involves a discrete modelling scheme for setup formulation so that the workload of machine spindles is levelled and its total cycle time is minimized. The so-formulated optimization problem, and related in particular to feature distribution among setups, can be successfully solved by a non-linear generalized reduced gradient (GRC) algorithm. The solution algorithms outlined can be relatively readily implemented in industrial informatics systems of small and medium-sized manufacturing enterprises. The entire methodical approach is validated through illustrative case studies based on exemplary mill-turn parts.

  • PLA–Potato Thermoplastic Starch Filament as a Sustainable Alternative to the Conventional PLA Filament: Processing, Characterization, and FFF 3D Printing
    • Agnieszka Haryńska
    • Helena Janik
    • Maciej Sienkiewicz
    • Barbara Mikolaszek
    • Justyna Kucińska-Lipka
    2021 Pełny tekst ACS Sustainable Chemistry & Engineering

    The growing popularity of the fused filament fabrication (FFF) 3D printing technology in science, industry, and in-home use is associated with an increased demand for high-quality polymer filaments. This study presents an in-depth characterization and analysis of a self-made bio-based polylactide (PLA)/thermoplastic potato starch (TPS) filament dedicated for the FFF 3D printing technology. The obtained results were compared with the commercial PLA filament (FF). The series of conducted studies (i.e., Fourier-transform infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis) revealed that both of the investigated filaments are stable under FFF 3D printing conditions. The mechanical test showed a correlation between the print orientation and raster angle on the strength features. The most favorable strengths values were recorded for the ZX_0° configuration, which were ∼18/22 MPa of tensile strength and ∼9/18 kJ m–2 of Charpy impact strength for the PLA/TPS filament and FF, respectively. Also, it was observed that the developed bio-filament has a more hydrophilic surface and is more susceptible to hydrolytic degradation in the phosphate-buffered saline solution than the FF. The composting study (according to the EN ISO 20200 standard) revealed that the commercial PLA printouts remain intact, while the PLA/TPS samples showed a mass loss of 19%. Finally, the remarkable printability of PLA/TPS was successfully demonstrated by FFF 3D printing of personalized anatomical models and complex porous structures.

  • Plasma free amino acid profiling as metabolomic diagnostic and prognostic biomarker in paediatric cancer patients: a follow‑up study
    • Anna Synakiewicz
    • Anna Stanisławska-Sachadyn
    • Małgorzata Sawicka-Żukowska
    • Grażyna Gałęzowska
    • Joanna Ratajczyk
    • Anna Owczarzak
    • Małgorzata Skuza
    • Lidia Wolska
    • Teresa Stachowicz-Stencel
    2021 Pełny tekst AMINO ACIDS

    Amino acids (AAs) play a crucial role in cancer cell metabolism. Levels of 22 plasma AAs at the time of diagnosis and after treatment were established among 39 pediatric cancer patients and 33 healthy children. Glutamic acid levels decreased and tryptophan levels increased during treatment. Cancer patients presented significantly lower levels of glutamine and leucine post-treatment while levels of 12 other AAs were higher comparing to controls. Results suggest that plasma free AA profile may serve as a prognostic biomarker.

  • Plasmon-enhanced photoluminescence from TiO2 and TeO2 thin films doped by Eu3+ for optoelectronic applications
    • Marcin Łapiński
    • Jakub Czubek
    • Katarzyna Drozdowska
    • Anna Synak
    • Wojciech Sadowski
    • Barbara Kościelska
    2021 Pełny tekst Beilstein Journal of Nanotechnology

    In this work we study the luminescence properties of europium-doped titanium dioxide and tellurium oxide thin films enhanced by gold plasmonic nanostructures. We propose a new type of plasmon structure with an ultrathin dielectric film between plasmonic platform and luminescent material. Plasmonic platforms were manufactured through thermal annealing of the gold thin film. Thermal dewetting of gold film results in spherical gold nanostructures with average dimensions of 50 nm. Both, luminescent TiO2:Eu and TeO2:Eu films were deposited by RF magnetron sputtering from mosaic targets. The morphology of the gold nanostructures was investigated by SEM and TEM, while the composition of oxides film was analyzed by XPS. Luminescence properties were studied on the basis of excitation and emission spectra. The experiments show that the additional dielectric layer enhances the luminescence intensity. Such structures could be potential candidates as phosphors in white LEDs.

  • Platforma aktywnego nauczania dla zwiększenia poziomu umiejętności techników i inżynierów
    • Marek Chodnicki
    2021 Pełny tekst Przegląd Spawalnictwa

    Przemysł 4.0 całkowicie przekształca sektor wytwórczy w Unii Europejskiej wprowadzając zasady cyfryzacji procesów przemysłowych. W rezultacie, nowe cyber-fizyczne systemy produkcyjne wywierają ogromny wpływ na siłę roboczą, a zwłaszcza na techników i inżynierów. Systemy te wymagają nowych hybrydowych zespołów "człowiek – maszyna", w których technicy i inżynierowie powinni umieć analizować zbiory danych Big Data, tworzyć symulacje linii produkcyjnych, koordynować pracę robotów, diagnozować/naprawiać złożone zautomatyzowane systemy. Dane pokazują jednak, że pracownicy przemysłowi nie są gotowi stawić czoła tej nowej rzeczywistości, ponieważ brakuje im odpowiednich umiejętności i wiedzy niezbędnej w nowym środowisku przemysłowym. Wydaje się, że pracownicy nie posiadają odpowiednich kwalifikacji, co z kolei ogranicza ich możliwości zatrudnienia jak i dostęp do dobrych zawodów. Ankieta European skills and jobs survey (ESJS) [1] wykazuje że 43% dorosłych pracowników doświadczyło ostatnio zmian technologii, której używają w pracy, a 47% odnotowało zmiany w metodzie pracy. Niemal 1 na 5 badanych uważa, że kilka z umiejętności jakie posiada staną się przestarzałe w ciągu kilku lat.

  • Podstawowe zagadnienia z mikrobiologii ogólnej
    • Agata Sommer
    2021

    W rozdziale opisano podstawowe zagadnienia z mikrobiologii ogólnej, przedstawiono podział mikroorganizmów i zaprezentowano metody oznaczania liczby drobnoustrojów.

  • Podstawy pól i fal elektromagnetycznych
    • Włodzimierz Zieniutycz
    2021

    W pracy przedstawiono w sposób systematyczny podstawowe zagadnienia elektromagnetyzmu. Materiał zawarto w dwunastu rozdziałach, w których zagadnienia teoretyczne, o ile to było możliwe, ilustrowano przykładami przybliżającymi Czytelnikowi ich sens fizyczny. Początkowe rozdziały poświęcono narzędziom matematycznym stosowanym w analizie zagadnień polowych oraz przedstawieniu koncepcji pól: elektrycznego i magnetycznego. Następnie omówiono równania Maxwella w próżni i w ośrodkach materialnych, warunki dla pól na granicy ośrodków oraz zagadnienia energetyczne (twierdzenie Poyntinga). Kolejne rozdziały poświęcono rozwiązaniu równań Maxwella i dyskusji własności fali płaskiej rozchodzącej się w ośrodku nieograniczonym oraz padającej na granicę ośrodków. Końcowy rozdział omawia propagację fal elektromagnetycznych w popularnych prowadnicach falowych. Dobór treści oraz układ pracy są efektem przemyśleń autora, który przez szereg lat prowadził wykłady z przedmiotów związanych z omawianą tematyką na Wydziale Elektroniki Telekomunikacji i Informatyki Politechniki Gdańskiej.

  • Pojęcie ideologii. Między krytyką ekonomii politycznej a hermeneutyką podejrzeń
    • Andrzej Karalus
    2021 Pełny tekst

    Monografia stanowi systematyczne i historyczne opracowanie zagadnienia "ideologii". Pojęcie to narodziło się pierwotnie w kontekście inspirowanej filozofią Hegla krytyki klasycznej ekonomii politycznej (Smith, Ricardo, Say) jako określenie na pewną społecznie reprodukowaną iluzję poznawczą , utrwalającą nierówności władzy i dominację klasową. Uległo ono następnie semantycznym przekształceniom i w drugiej połowie XX wieku stało się wraz z "rodziną" znaczeniowo pokrewnych pojęć (takich jak "dyskurs", interpelacja", "hegemonia" czy "mit") narzędziem krytycznego badania społeczeństwa i kultury oraz wpisanych weń relacji władzy. W ostatnich dwóch dekadach widać jednak stopniowy powrót do klasycznych (klasowych, ekonomicznych) wykładni zagadnienia ideologii, zwłaszcza w kontekście krytyki neoliberalizmu i w reakcji na globalny kryzys kapitalizmu (zagrożenie ekologiczne, nierówności dochodowe, kryzys finansowy).

  • Poland's economic relations with Uzbekistan
    • Krystyna Gomółka
    2021 Pełny tekst Studia Wschodnioeuropejskie

    The article describes economic relations between Poland and Uzbekistan 1992-2020