Nowe zasoby w kolekcji Artykuły i czasopisma http://suw.biblos.pk.edu.pl/ Biblioteka Politechniki Krakowskiej lipinska@biblos.pk.edu.pl 60 <![CDATA[2D digital reconstruction of asphalt concrete microstructure for numerical modeling purposes]]> Tue, 16 Aug 2022 14:17:40 +0200 Klimczak, Marek; Jaworska, Irena; Tekieli, Marcin
rodzaj: artykuł w czasopiśmie
Abstrakt: In this paper, we deal with the issue of asphalt concrete microstructure recognition for further numerical analysis. An efficient reconstruction of the underlying microstructure makes the composite analysis more reliable. We propose for this purpose a methodology based on the image processing and focus on a two-dimensional case (it can be easily used as a part of the 3D geometry reconstruction, however). Initially obtained geometry of the inclusions is further simplified to reduce the cost of the finite element mesh generation. Three straightforward geometry simplification algorithms are used to perform this process in a controlled way. Subsequently, we present the solutions of two problems, i.e., heat flow and elasticity (plane strain), in order to illustrate the effectiveness of the whole elaborated methodology. The numerical results were obtained using the finite element method. Consequently, an error analysis is demonstrated in order to refer the overkill mesh solutions to the ones presented in this study. The main finding of this paper is the efficient methodology dedicated to a digital reconstruction of the asphalt concrete microstructure by the image processing. It can be also extended to other materials exhibiting similar microstructure.]]>
<![CDATA[Impact of salt crystallization on the mechanical properties of structural masonry: An experimental and numerical study]]> Tue, 16 Aug 2022 13:55:13 +0200 Pietruszczak, S.; Przecherski, P.; Stryszewska, T.
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Abstrakt: This paper provides the results of an experimental study examining the evolution of mechanical properties of primary constituents of structural masonry (i.e., brick units, mortar and brick–mortar interfaces) during the process of salt crystallization. The precipitated salt changes the pore structure. At the early stages, the porosity decreases which enhances the mechanical performance. However, as the concentration of precipitated salt increases further, the internal damage within the porous matrix leads to a progressive degradation of mechanical properties. The aim of this research is to assesses the impact of salt crystallization on the conditions at failure and the stiffness characteristics of the constituent materials. The evolution laws are expressed in terms of a parameter which represents the degree of accumulation of salt precipitated in pore space. The general form of an elastoplastic constitutive relation, employing this parameter, is briefly discussed and the results of some preliminary numerical simulations are given.]]>
<![CDATA[Thermal and flow calculations of platen superheater in large scale CFB boiler]]> Thu, 11 Aug 2022 11:23:08 +0200 Madejski, Paweł; Taler, Dawid; Taler, Jan
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Abstrakt: Circulating Fluidized Bed (CFB) boilers are desirable technology to utilize solid fuels, operate within a wide load range, and promote the high flexibility in burning a wide range of coal and other solid fuels, keeping high efficiency and low gaseous pollution. The paper presents thermal and flow modeling results of steam superheater operated in the large-scale coal-fired CFB boiler, both in steady and transient states. The mathematical model of the superheater wall was developed using Control Volume-based Finite Element Method. The heat transfer coefficient as the sum of radiative and convective heat transfer coefficients was considered in the presented approach to modeling thermal processes in a circulating fluidized bed. The overall heat transfer coefficient was computed for the analyzed type of the boiler at full load and steady-state conditions using available measuring data and results obtained using Computational Fluid Dynamics (CFD) modeling. Depending on the modeling approach adopted in the CFD model, the heat transfer coefficient at full boiler load varies between 159.96 and 189.63 W/(m2·K). In the analyzed period of boiler start-up, results of steam outlet temperature (455 °C–485 °C), heat transfer coefficients on the flue-gas side (100 W/(m2∙K) and 120 W/(m2∙K)), and heat transfer coefficients on the steam-side (925–2008 W/(m2∙K)) vary with time. The methods presented in the paper can be applied to modeling transient flow and thermal processes in superheaters with complicated flow arrangements. The advantage of the proposed method is a short computing time compared to detailed and complex 3D models. The developed model of the superheater with the transfer coefficient determination methods can be used to perform calculations in the full range of boiler load, both during steady and transient boiler operation.]]>
<![CDATA[Progress in smart and sustainable technologies]]> Wed, 10 Aug 2022 12:12:57 +0200 Nižetić, Sandro; Ocłoń, Paweł; Tsoutsos, Theocharis
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Abstrakt: Digitalization in various engineering fields enables a path to progressive development possibilities that are nowadays mainly focused on the utilization of smart technologies in different applications. The implementation of smart technologies leads to more efficient customer oriented services, increases process efficiency, provides better security, i.e. ensures a wide range of technological advancements. An important aspect linked with the fast development of smart technologies is related to environmental implications that need to be carefully considered. This review editorial is focused on the research contributions presented at the 5th International Conference on Smart and Sustainable Technologies held in Split and Bol, Croatia, in 2020 (SpliTech2020). The focus of the conference was directed towards key conference tracks such as Smart City, Energy/Environment, e-Health and Engineering Modelling. Several main topical areas were discussed in the herein editorial, i.e. latest advancements in further fields such as: Energy Sector, Circular Economy, Environmental protection, etc. The research presented and discussed at the SpliTech2020 conference helped in understanding current progress and research directions in the field of smart technologies and highlighted their sustainability aspect.]]>
<![CDATA[A comparison study on magnetorheological multi-disc clutches in steady continuous-duty states from the viewpoint of electrical energy consumption and spatial temperature distribution]]> Wed, 10 Aug 2022 10:43:38 +0200 Kluszczyński, Krzysztof; Pilch, Zbigniew
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Abstrakt: The paper is focused on magnetorheological (MR) clutches applied in industrial drive systems working in a steady continuous-duty state. The main goal of the carried out numerical and analytical analyses oriented towards electrical power consumption, copper losses (Joule heat) in an excitation coil, spatial temperature distributions and the highest temperature possible for an MR fluid is to compare MR clutches due to a different number of discs. The authors considered selected representative MR multi-disc clutches with one, two, three or four discs, developing clutching torque Tc equal to 20, 35 and 50 Nm. These clutches were constructed based on the in-house design that integrates analytical and field methods (further in the paper referred to as the integrated analyticalfield design method) described in the literature. The thermal computer simulation results obtained with the help of the AGROS2D program, combined with findings achieved with the use of simplified physical reasonings, allow one to draw the conclusion that the most advantageous, recommended number of discs for a magnetorheological clutch from the viewpoint of various (both constructional and thermal) criteria is the number of discs: N = 2. This conclusion takes into account the results presented earlier in the literature: the choice is a compromise between decreasing the mass (volume) of the MR clutches and increasing both the electrical power consumption and the maximum temperature of MR fluids in a clutch working region as the number of discs, N, increases.]]>
<![CDATA[Research on the hourly water consumption structure in rural and suburban household]]> Tue, 09 Aug 2022 12:32:27 +0200 Młyńska, Anna; Bergel, Tomasz
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Abstrakt: Currently, the character of many households located in rural areas is closer to that of suburban households. The change in the characters of households located in rural areas results in changes in the size and irregularity of water demand, which should translate into a new approach at the stage of water supply systems designing. Therefore, in order to supplement the state of knowledge in this study area, this paper presents the results of the research on the structure of hourly water consumption in two households located in rural areas; the first household had a suburban character, whereas the second one was a typical rural household. The results showed differences in the amount and the distribution of hourly water consumption in the analyzed households. Except on weekends, the average hourly water consumption in rural household was higher than in suburban household. In contrast, in the rural household, the distribution of hourly water consumption on all days of the week was very similar and the peak water consumption was clearly marking in the morning and in the evening. In the case of the suburban household, a tendency of increased water consumption in the evening was observed, but without clearly noticeable peak water consumption. Moreover, the structure of hourly water consumption in suburban household on Saturday and Sunday was different than on weekdays. The analyzed households were characterized by the highest share of hourly water consumption up to 20.0 dm3·h-1. In the rural household, both the amount and the distribution of hourly water consumption were determined by water use for additional purposes. In the case of the suburban household, it was shaped by the living needs of the inhabitants.]]>
<![CDATA[Wykorzystanie odpadów wydobywczych modyfikowanych wapnem do budowy wałów przeciwpowodziowych]]> Tue, 09 Aug 2022 12:28:31 +0200 Pilecka, Elżbieta; Morman-Wątor, Justyna
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Abstrakt: W artykule przedstawiono wyniki badań właściwości fizycznych i mechanicznych odpadów wydobywczych o uziarnieniu mniejszym od 2 mm, zmodyfikowanych spoiwem wapiennym, w aspekcie wykorzystania ich jako materiału budowlanego do budowy wałów przeciwpowodziowych. Wyniki badań laboratoryjnych wskazują na poprawianie właściwości fizycznych, a przede wszystkim zmniejszenie współczynnika filtracji o 98%.Analiza wyników obliczeń MES modelu wału przeciwpowodziowego w programie MIDAS wykazała zwiększenie współczynnika stateczności do bezpiecznego poziomu.]]>
<![CDATA[Analysis of a landslide on a railway track using laser scanning and FEM numerical modelling]]> Tue, 09 Aug 2022 12:24:37 +0200 Pilecka, Elżbieta; Szwarkowski, Dariusz; Stanisz, Jacek; Blockus, Marcin
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Abstrakt: In this study, we present an analysis of the causes of a landslide along a railway track in the Polish Lowlands. The landslide damaged the railway track and caused significant material losses. Digital models of the terrain surface before and after the landslide were elaborated. Remote sensing using LIDAR aerial technique and a terrestrial laser scanner was performed to determine the morphology. Soil mass behaviour was analysed by 3D numerical simulation. A numerical model was created based on geotechnical tests. Taking into account the behaviour of the dry and wet models, the numerical simulation showed the most probable scenario of mass movement. The main reasons for the landslide were rainwater infiltration in the track basement and the unfavourable morphology of the area on which the railway embankment was located. The study demonstrates that combined methods—laser scanning, geotechnical testing of the soil material, and 3-dimensional numerical simulation—enabled the assessment of the causes of the analysed landslide.]]>
<![CDATA[Influence of elbow angle on erosion-corrosion of 1018 steel for gas–liquid–solid three phase flow]]> Tue, 09 Aug 2022 12:18:46 +0200 Khan, Rehan; Ya, Hamdan H.; Shah, Imran; Niazi, Usama Muhammad; Ahmed, Bilal Anjum; Irfan, Muhammad; Glowacz, Adam; Pilch, Zbigniew; Brumercik, Frantisek; Azeem, Mohammad; Alam, Mohammad Azad; Ahmed, Tauseef
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Abstrakt: Erosive wear due to the fact of sand severely affects hydrocarbon production industries and, consequently, various sectors of the mineral processing industry. In this study, the effect of the elbow geometrical configuration on the erosive wear of carbon steel for silt–water–air flow conditions were investigated using material loss analysis, surface roughness analysis, and microscopic imaging technique. Experiments were performed under the plug flow conditions in a closed flow loop at standard atmospheric pressure. Water and air plug flow and the disperse phase was silt (silica sand) with a 2.5 wt % concentration, and a silt grain size of 70 µm was used for performing the tests. The experimental analysis showed that silt impact increases material disintegration up to 1.8 times with a change in the elbow configuration from 60◦ to 90◦ in plug flow conditions. The primary erosive wear mechanisms of the internal elbow surface were sliding, cutting, and pit propagation. The maximum silt particle impaction was located at the outer curvature in the 50◦ position in 60◦ elbows and the 80◦ position in 90◦ elbows in plug flow. The erosion rate decreased from 10.23 to 5.67 mm/year with a change in the elbow angle from 90◦ to 60◦ . Moreover, the microhardness on the Vickers scale increased from 168 to 199 in the 90◦ elbow and from 168 to 184 in the 60◦ elbow.]]>
<![CDATA[A review of methods for the isolation of microplastics in municipal wastewater treatment]]> Tue, 09 Aug 2022 11:48:13 +0200 Ormaniec, Paulina; Mikosz, Jerzy
rodzaj: artykuł w czasopiśmie
Abstrakt: Wastewater treatment plants are considered to be one of the largest sources of microplastics in the natural environment. The problem of microplastics has been widely studied in many environments. It remains a subject of the growing interest for researchers. By definition, microplastic is plastic that does not exceed 5 mm in size. There are three stages in the study of microplastics in wastewater: sampling, treatment, and the identification of microplastics. This paper aims to review the strategies for sampling microplastics in wastewater treatment plants and their laboratory treatment to isolate microplastics. The collection of samples from the wastewater treatment plant is based on two mechanisms, namely a continuous filtering and pumping system and instantaneous sampling (steel bucket, glass jar, telescopic sampling). The removal of organic and inorganic matter is carried out with the use of physical and chemical analyses. The subject of this article is the compilation of the generally available research methods on microplastics. Based on the literature analysis, conclusions were drawn regarding the recommended methods of microplastic detection.]]>
<![CDATA[Selected physical and spectroscopic properties of TPS moldings enriched with durum wheat bran]]> Tue, 09 Aug 2022 11:40:58 +0200 Combrzyński, Maciej; Wójtowicz, Agnieszka; Oniszczuk, Anna; Karcz, Dariusz; Szponar, Jarosław; Matwijczuk, Arkadiusz P.
rodzaj: artykuł w czasopiśmie
Abstrakt: The impact of the amount of durum wheat bran additive used on the selected structural, mechanical, and spectroscopic properties of thermoplastic starch moldings was examined in this study. Bran was added to corn starch from 10 to 60% by weight in the blends. Four temperature settings were used for the high-pressure injection: 120, 140, 160, and 180 °C. The highest value of elongation at break (8.53%) was observed for moldings containing 60% bran. Moreover, for these moldings, the tensile strength and flexural strength were lower (appropriately 3.43 MPa and 27.14 MPa). The highest deformation at break (1.56%) were obtained for samples with 60% bran and injection molded at 180 °C. We saw that higher bran content (50 and 60%) and a higher injection molding temperature (160 °C and 180 °C) significantly changed the color of the samples. The most significant changes in the FTIR spectra were observed at 3292 and 1644 cm−1 and in the region of 1460–1240 cm−1. Moreover, notable changes were observed in the intensity ratio of bands at 1015 and 955 cm−1. The changes observed correspond well with the amount of additive used and with the injection temperature applied; thus it may be considered as a marker of interactions affecting plasticization of the material obtained.]]>
<![CDATA[The use of combined quality management instruments to analyze the causes of non-conformities in the castings of the cover of the rail vehicle bearing housing]]> Tue, 09 Aug 2022 11:35:12 +0200 Czerwińska, Karolina; Piwowarczyk, Adam
rodzaj: artykuł w czasopiśmie
Abstrakt: The most critical activities influencing the success of each company are continuous improvement of the quality of manufactured products and monitoring of the production process. Skillful use of avail-able technologies and quality management tools allows for eliminating casting non-conformities and preventing their repetition in the future. The research aimed to analyze the types of defects occurring in castings, the location of their most frequent occurrence areas, and to identify the causes of defects in castings of bearing housings used in rail vehicles. The benefits of a combination of quality manage-ment tools for diagnosing material discontinuities in the analyzed castings are presented in this article. ]]>
<![CDATA[Air-side Nusselt numbers and friction factor’s individual correlations of finned heat exchangers]]> Tue, 09 Aug 2022 09:43:38 +0200 Marcinkowski, Mateusz; Taler, Dawid; Taler, Jan; Węglarz, Katarzyna
rodzaj: artykuł w czasopiśmie
Abstrakt: Currently, when designing finned heat exchangers (FHE), the average value of the entire heat transfer coefficient (HTC) is considered. However, each row of the heat exchanger (HEX) has different hydraulic-thermal characteristics. The novelty of this research is to present the differentiation of the individual air-side Nusselt number and Darcy-Weisbach friction factor correlations in each row of FHE using CFD modelling. FHE has four-rows, circular tubes, and continuous fins with a staggered tube arrangement. Relationships for the Nusselt number and D-W friction factor derived for the entire exchanger based on CFD modelling were compared with those available in the literature, determined using experimental data. The maximum relative differences between the Nusselt number for a four-row FHE determined experimentally and by CFD modelling are in the range from 22% for a Reynolds number based on a tube outside diameter of 1000 to 30% for a Reynolds number of 13,000. The maximum relative differences between the D-W friction factor for a four-row FHE determined experimentally and by CFD modelling are in the range of 50% for a Reynolds number based on a tube outer diameter of 1000 to 10% for a Reynolds number of 13,000. The CFD modelling performed shows that in the range of Reynolds numbers based on hydraulic diameters from 150 to 1400, the Nusselt number for the first row in a four-row FHE is about 22% to 15% higher than the average Nusselt number for the entire exchanger. In the range of Reynolds number changes based on hydraulic diameter from 2800 to 6000, the Nusselt numbers on the first and second rows of tubes are close to each other. Correlations of Nusselt numbers and D-W friction factors derived for individual tube rows can be used in the design of plate-fin and tube heat exchangers used in equipment such as air-source heat pumps, automotive radiators, air-conditioning systems, and in air hot-liquid coolers. In particular, the correlations can be used to select the optimum number of tube rows in the exchanger.]]>
<![CDATA[Integral equation-based simulation of transient experiments for an EC2 mechanism: beyond the steady state simplification]]> Tue, 09 Aug 2022 09:38:07 +0200 Bieniasz, Lesław K.; Vynnycky, Michael; McKee, Sean
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Abstrakt: Transient electrochemical experiments are usually described theoretically by systems of reaction–diffusion partial differential equations. Converting them to integral equations is a classical and valuable modelling approach. Unfortunately, if any reaction–diffusion equation contains nonlinear reaction rate terms, up to now such a conversion has only been possible by assuming a steady state for the equation. Consequently, only sufficiently fast homogeneous reactions could be handled. In this work a novel integral equation-based modelling approach is described. The steady state assumption is replaced by a two-term singular perturbation expansion of the concentration–flux relationship, recently published by the authors. The expansion is valid for homogeneous reactions of (integer) order m>=1, occurring at planar electrodes. An example simulation of cyclic voltammetry for an EC2 reaction mechanism involving a second order dimerization reaction is performed. It is found that in this way the voltammograms can be satisfactorily simulated for homogeneous reaction rate constants smaller by about one order of magnitude than was previously possible.]]>
<![CDATA[Bio-Morpheme as innovative design concept for "Bio City" urban structure in the context of water-saving and human health]]> Mon, 08 Aug 2022 10:09:42 +0200 Rybicki, Stanisław M.; Schneider-Skalska, Grażyna; Stochel-Cyunel, Jadwiga
rodzaj: artykuł w czasopiśmie
Abstrakt: This paper presents a novel model of an elementary autonomous housing complex called Bio-Morpheme, intended to be an element of a Bio-City's structure. Its novelty manifests from the idea of urban form integration with the form of the water transformation cycle in the building and its immediate surroundings. Key factors include the retention and utilisation of rainwater in the Bio-Morpheme. Another feature of the proposal is the potential to use Bio-Morpheme-like complexes as autonomous units or combine them into larger structures based on integrated water management in typologically diverse city zones. Define the urban and architectural features of a Bio-Morpheme complex allowed using the proposed theoretical model to verify the potential for comprehensive water management featuring the utilisation of rainwater and stormwater harvested from roofs, pavements, bicycle paths, and roads. The study assumed climate and hydrological conditions for Krakow, Poland, predicting the potential for application. The authors observed that a Bio-Morpheme's structure allows for incorporating 41% of the collected runoff into its water supply infrastructure and using this water for domestic purposes when the remaining water can be direct to a surface reservoir. The reservoir provides the Bio-Morpheme's residents with direct contact with a water surface and enhances the microclimate. The Bio-Morpheme model is a solution that allows for rationalizing processes in elementary urban structure cells, which has a beneficial effect on lowering the demand for grid-sourced water and the amount of sewage produced. It also allows for introducing a surface reservoir into an urban interior and guarantees the highest quality of the environment and the health of residents.]]>
<![CDATA[From the source to the reservoir and beyond – tracking sediment particles with modeling tools under climate change predictions (Carpathian Mts.)]]> Fri, 05 Aug 2022 13:08:01 +0200 Wilk, Paweł; Szlapa, Monika; Hachaj, Paweł S.; Orlińska-Woźniak, Paulina; Jakusik, Ewa; Szalińska, Ewa
rodzaj: artykuł w czasopiśmie
Abstrakt: Purpose: The study tracks spatial and temporal distribution of sediment particles from their source to the deposition area in a dammed reservoir. This is particularly important due to the predicted future climate changes, which will increase the severity of problems with sediment transport, especially in catchments prone to erosion. Methods: Analyses were performed with a monthly step for two mineral and one mineral/organic sediment fractions delivered from the Carpathian Mts. catchment (Raba River) to the drinking water reservoir (Dobczyce) by combining SWAT (Soil and Water Assessment Tool), and AdH/PTM (Adaptive Hydraulics Model/Particle Tracking Model) modules on the digital platform— Macromodel DNS (Discharge Nutrient Sea). To take into account future changes in this catchment, a variant scenario analysis including RCP (representative concentration pathways) 4.5 and 8.5, and land use change forecasts, was performed. Results: The differences between the two analyzed hydrological units (catchment and reservoir) have been highlighted and showed a large variability of the sediment load between months. The predicted climate changes will cause a significant increase of mineral fraction loads (silt and clay) during months with high flows. Due to the location and natural arrangement of the reservoir, silt particles will mainly affect faster loss of the first two reservoir zones capacities. Conclusions: The increased mobility of finer particles (clay) in the reservoir may be more problematic in the future, mainly due to their binding pollutant properties, and the possible negative impact on drinking water abstraction from the last res‑ ervoir zone. Moreover, the study shows that the monthly approach to forecasting the impact of climate change on sediment loads in the reservoir is recommended, instead of a seasonal one.]]>
<![CDATA[The potential of selected plant extracts in anti-acne skincare formulations]]> Fri, 05 Aug 2022 12:20:59 +0200 Dziki, A.; Matusik-Tabor, A.; Malinowska, M. A.
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Abstrakt: Consumers' awareness and the desire to reach for cosmetics with natural ingredients are still growing. The active ingredients of plants have the ability to reduce acne lesions and skin redness accompanying them. Anti-acne products containing therapeutic agents reducing visible skin inflammation should be supported by the specialized cosmetic formulations. These products should act simultaneously, ensuring proper skin care due to the content of plant metabolites exhibiting desired biological activity. In this study, the application of a selected plant extract in cosmetic preparations for acne skin care containing selected plant extracts were prepared: Arnica montana flower, Sambucus nigra and Rosmarinus officinalis leaf, Saponaria officinalis root, Aloe barbadensis leaf juice and Silybum marianum seed oil and then their effects were compared. The extracts obtained were applied as active ingredients in the formulations of face cream, serum and micellar solution. The physicochemical properties (pH value, stability, dispersed phase particle size and type of emulsion) were evaluated, moreover, rheological tests of the samples were carried out and the skin cleansing ability of the micellar solution was examined. In addition, all the formulations were subject to various tests which allowed to evaluate their organoleptic properties. It was noticed that the used plant raw materials have an effect supporting the care of the skin with acne tendencies. Both extracts (Arnica montana flower extract and Sambucus nigra extract) were used in the same concentrations in the cosmetics so that differences in results were easy to compare. Importantly, during the consumer tests, the probants discontinued usage of other anti-acne agents applied normally, which allowed for an objective assessment of the effect of the tested extracts on the acne skin. The formulations tested were proven to be effective cosmetics supporting anti-acne therapy.]]>
<![CDATA[Excavations in the vicinity of the antiflood embankments – calculating issues]]> Fri, 05 Aug 2022 10:45:55 +0200 Grodecki, Michał
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Abstrakt: According to Polish law, it is prohibited to perform excavations or locate buildings closer than 50 m from the embankment. In order to obtain exemption from this ban, filtration and stability analysis of the embankment and excavation in the flood conditions have to be performed. This paper presents results of the numerical investigations on interactions between excavations and embankment. Complex nature of the problem is presented. Methodology of numerical simulations and real case examples are described.]]>
<![CDATA[E-usługi w Bibliotece Politechniki Krakowskiej – realizacja zaplanowanej strategii czy odpowiedź na aktualne zapotrzebowanie?]]> Fri, 05 Aug 2022 10:31:45 +0200 Buzdygan, Dorota; Pietrukowicz, Maria
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Abstrakt: W artykule zaprezentowano wpływ pandemii koronawirusa na działalność Biblio-teki Politechniki Krakowskiej (BPK). Przedstawiono obszary działalności BPK, w których zmiana sposobu realizacji usług, z tradycyjnych na elektroniczne, została ugruntowana lub przyspieszona pod wpływem wprowadzonego lockdownu. Omówiono szereg oferowanych przez BPK e-usług, wśród nich przygotowaną we współpracy z jednostkami Politechniki Krakowskiej usługę udostępniania podręczników w elektronicznej wersji. Przybliżono także zaplanowane działania biblioteki, mające na celu poszerzanie oferty zbiorów i usług.]]>
<![CDATA[A novel design and development of a strip-fed circularly polarized rectangular dielectric resonator antenna for 5G NR Sub-6 GHz band applications]]> Fri, 05 Aug 2022 10:27:08 +0200 Illahi, Usman; Iqbal, Javed; Irfan, Muhammad; Sulaiman, Mohamad Ismail; Khan, Muhammad Abbas; Rauf, Abdul; Bari, Inam; Abdullah, Mujeeb; Muhammad, Fazal; Nowakowski, Grzegorz; Glowacz, Adam
rodzaj: artykuł w czasopiśmie
Abstrakt: In this article, a rectangular dielectric resonator antenna (RDRA) with circularly polarized (CP) response is presented for 5G NR (New Radio) Sub-6 GHz band applications. A uniquely shaped conformal metal feeding strip is proposed to excite the RDRA in higher-order mode for high gain utilization. By using the proposed feeding mechanism, the degenerate mode pair of the first higherorder, i.e., TEx δ13 at 4.13 GHz and TEy 1δ3 , at 4.52 GHz is excited to achieve a circularly polarized response. A circular polarization over a bandwidth of ~10%, in conjunction with a wide impedance matching over a bandwidth of ~17%, were attained by the antenna. The CP antenna proposed offers a useful gain of ~6.2 dBic. The achieved CP bandwidth of the RDRA is good enough to cover the targeted 5G NR bands around 4.4–4.8 GHz, such as n79. The proposed antenna configuration is modelled and optimized using computer simulation technology (CST). A prototype was built to confirm (validate) the performance estimated through simulation. A good agreement was observed between simulated and measured results.]]>
<![CDATA[A review to diagnose faults related to three-phase industrial induction motors]]> Thu, 04 Aug 2022 13:12:24 +0200 Sheikh, Muhammad Aman; Bakhsh, Sheikh Tahir; Irfan, Muhammad; Nor, Nursyarizal bin Mohd; Nowakowski, Grzegorz
rodzaj: artykuł w czasopiśmie
Abstrakt: The induction motor is one of the essential components of the industry. In industrial applications, the controllability, protection, and reliability of induction motors are of major concern to reserve energy. Thus, condition monitoring of an induction motor is critical for improving the unit’s reliability and, as a result, reducing downtime, labor, reducing energy wastage. Induction motor stator winding and bearing failures account for 37% and 41% of failures, respectively. As the sophisticated controls rely on parameters of the motor, while the protection and reliability depend on continuous and accurate monitoring of the health of the motor. This paper covers the state of the art of parameter estimation and condition monitoring of induction motors in order to help out the industry to minimize energy wastage. In order to assist the exact operation of an induction motor, initially, the fundamentals, structure, and model of an induction motor are explained. Further, this paper covers fault diagnoses that are capable of finding the symptoms of motor failure through the state of the art of parameter estimation. In addition, the medium for the root cause of an induction motor failure is described. Finally, the paper is concluded with what has been done already, the knowledge gap, and the potential of future research.]]>