Herbert De Gersem, Mariana Ion, Markus Wilke, Thomas Weiland and Andrzej Demenko
To propose trigonometric interpolation in combination with both sliding‐surface and moving‐band techniques for modelling rotation in finite‐element electrical machine models. To…
Abstract
Purpose
To propose trigonometric interpolation in combination with both sliding‐surface and moving‐band techniques for modelling rotation in finite‐element electrical machine models. To show that trigonometric interpolation is at least as accurate and efficient as standard stator‐rotor coupling schemes.
Design/methodology/approach
Trigonometric interpolation is explained concisely and put in a historical perspective. Characteristic drawbacks of trigonometric interpolation are alleviated one by one. A comparison with the more common locked‐step linear‐interpolation and mortar‐element approaches is carried out.
Findings
Trigonometric interpolation offers a higher accuracy and therefore can outperform standard stator‐rotor coupling techniques when equipped with an appropriate iterative solver incorporating Fast Fourier Transforms to reduce the higher computational cost.
Originality/value
The synthetic interpretation of trigonometric interpolation as a spectral‐element approach in the machine's air gap, the efficient iterative solver combining conjugate gradients with Fast Fourier Transforms. The unified application to both sliding‐surface and moving‐band techniques.
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Mariana Ion, Herbert De Gersem, Markus Wilke and Thomas Weiland
To propose trigonometric interpolation in combination with the sliding‐surface technique for modeling rotation in electrical machine models discretised by the finite integration…
Abstract
Purpose
To propose trigonometric interpolation in combination with the sliding‐surface technique for modeling rotation in electrical machine models discretised by the finite integration technique (FIT).
Design/methodology/approach
Locked‐step, linear and trigonometric interpolation techniques are developed for coupling the stator and rotor model parts of an electrical machine model.
Findings
Linear and trigonometric interpolation should be preferred over the locked‐step approach. Three‐machine models with sliding‐surface coupling discretised by the FIT result in efficient and reliable models.
Originality/value
The introduction of sliding‐surface techniques in the FIT, the trigonometric interpolation used in combination, the application of the FIT for simulating electrical machines.
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Suhendrayatna, Muhammad Zaki, Annisa Delima Habdani Harahap and Fitriani Verantika
Purpose – In this study, the possibility of the application of rice husks for adsorbing Mn(II) ion in the water phase has been studied.Design/Methodology/Approach – Experimental…
Abstract
Purpose – In this study, the possibility of the application of rice husks for adsorbing Mn(II) ion in the water phase has been studied.
Design/Methodology/Approach – Experimental studies have been initiated by preparing activated carbon from rice husks. The activation of rice husks was done using both physical and chemical treatment methods through heating at 110 °C and washing with citric acid activator at 0.2 M, 0.4 M, and 0.6 M. The adsorption tests were conducted as two part tests: preliminary and primary. The preliminary test was conducted to choose the best condition of four independent variables, i.e., contact time (0–120 minutes), activator concentrations (0.2, 0.4, and 0.6 M), initial Mn(II) concentrations (10, 20, 50, 100, 200, and 400 mg/L), and adsorption temperatures (30, 47, and 67 °C).
Findings – By identifying the substituted groups using Fourier Transform Infrared Spectroscopy after activation with citric acid, it was found that the highest transmittance percentage was present in activated carbon with 0.2 M of citric acid. The best adsorption capacity and efficiency was 13.87 mg/g and 79.60%, respectively, which were obtained at 200 mg/L initial concentration with a 0.2 M citric acid concentration for 120 min contact time at 47 °C. These results lead to a conclusion that rice husks after activation with citric acid can be applied as an adsorbent for Mn(II) adsorption in the water phase.
Research Limitations/Implications – The activated carbon produced was only applicable for the adsorption of Mn(II) ions from the water phase, but not applicable for the adsorption of other heavy metals ions.
Practical Implications – Rice husks were potentially prepared as an adsorbent for Mn(II) ion adsorption in the water phase that was low cost, environmental friendly, and easy to prepare.
Originality/Value – Activated carbon prepared from biomass was mostly carried out using acids at high concentrations while the study was conducted using weak acids (citric acid) at low concentrations.
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Ivan M. Zin, Vasyl I. Pokhmurskii, Sergiy A. Korniy, Olena V. Karpenko, Stuart B. Lyon, Olha P. Khlopyk and Mariana B. Tymus
The purpose of this paper is to study the influence of rhamnolipid biosurfactant complex on the corrosion and the repassivation of a freshly cut Al-Cu-Mg aluminium alloy surface.
Abstract
Purpose
The purpose of this paper is to study the influence of rhamnolipid biosurfactant complex on the corrosion and the repassivation of a freshly cut Al-Cu-Mg aluminium alloy surface.
Design/methodology/approach
The electrochemical methods, supported by quantum-chemical calculations and scanning electron microscopy data, were used.
Findings
It was established that the rhamnolipid biosurfactant effectively inhibits corrosion of the alloy in synthetic acid rainwater. The efficiency of inhibition becomes stronger with the increase of biosurfactant concentration; however, above the critical micelle concentration, the further improvement in inhibition is minor. It is believed that the mechanism of corrosion inhibition is related to the adsorption of the biosurfactant molecule on the aluminium alloy surface and the formation of a barrier film; however, the formation of a complex compound (salt film) between aluminium ions and rhamnolipid on anodic sites of the alloy is not ruled out. In case of surface mechanical activation of the alloy, the biosurfactant molecule effectively prevents corrosion. Furthermore, addition of the biosurfactant to the corrosion environment increases the repassivation kinetics of the alloy by two to four times as compared with an uninhibited environment.
Practical implications
The commercial impact of the study consists in the possibility of obtaining of environmentally safe corrosion inhibitors of aluminium alloys by biosynthesis from renewable agricultural raw materials.
Originality/value
The originality of this paper is to study the effectiveness of “green” corrosion inhibitor based on biogenic product on freshly generated surface of aluminium alloy.
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Mirela Cătălina Türkeş, Aurelia Felicia Stăncioiu, Mihai Cristian Orzan, Mariana Jugănaru, Roxana-Cristina Marinescu and Ion Dănuț Jugănaru
Almost four years after the COVID-19 pandemic, the changes in the labour market and legislation, but also in people's lives, do not stop. At the same time, employees' perceptions…
Abstract
Purpose
Almost four years after the COVID-19 pandemic, the changes in the labour market and legislation, but also in people's lives, do not stop. At the same time, employees' perceptions regarding the change in the legislative and contractual framework, as well as in the working conditions and the use of telework, also change. Therefore, the aim of the paper is to identify the perceptions of employees regarding the use of telework in the post-pandemic period.
Design/methodology/approach
The research was based on a survey carried out on 128 teleworkers in the post-pandemic period. The statistical hypotheses were tested using Kolmogorov–Smirnov and Kruskal–Wallis tests, multiple linear regression and pairwise comparison analysis.
Findings
The results of the study demonstrate that the modification of the legislative and contractual framework and of the working conditions, as well as of the way of using information and communication technology in the post-pandemic era, generates a positive and significant impact on the use of telework by employees. Some of the main advantages valued by teleworkers included the possibility of benefitting from a flexible work schedule and the possibility of reducing transport costs.
Originality/value
The study highlights the need to continuously develop and update labour policies and strategies in line with current and future labour market requirements, considering the implications of telework on the perceptions of employees, so that government organisations and managers who want to protect the rights and interests of teleworkers, aspects of their lives and organise an appropriate work environment manage to do so in order to achieve the expected results.
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Daniela da Costa de Oliveira, Amanda Cristina Cristina Andrade, Jéssica Guimarães, Jéssica Ferreira Rodrigues, Mariana Mirelle Pereira Natividade and Sabrina Carvalho Bastos
Excessive sodium intake is associated with several diseases. Accordingly, several measures, including microparticulate salt, have been adopted to reduce the salt contents of food…
Abstract
Purpose
Excessive sodium intake is associated with several diseases. Accordingly, several measures, including microparticulate salt, have been adopted to reduce the salt contents of food products. However, no studies have reported the effectiveness of microparticulate salt in semisolid and liquid products. Accordingly, the purpose of this paper is to evaluate the application of microparticulate salt to reduce sodium contents in semisolid products.
Design/methodology/approach
The optimal salt content to be added in butter was defined by the just-about-right-scale test. Butter samples were prepared using microparticulate salt to achieve 25, 50 and 75 per cent reductions in conventional salt concentrations. Multiple comparison tests were performed to evaluate sample taste.
Findings
The ideal concentration of conventional salt to be added to butter was 2.16 per cent. Discriminative tests showed that samples with 25 and 75 per cent salt reduction showed significant differences (p ⩽ 0.05) compared with butter prepared at the ideal salt content, whereas the sample with 50 per cent salt reduction had no significant difference (p > 0.05). Thus, microparticulate salt showed higher salting power than conventional salt. These results indicated the effectiveness of microparticulate salt in the preparation of semisolid products with sodium reduction.
Research limitations/implications
More detailed studies about the reduced-sodium butter shelf life are necessary to verify the microparticulate salt application in the product preparation. Moreover, microparticulate salt application in semisolid and liquid products elaboration must be more investigated to better elucidate its practicability of reducing sodium content in these kinds of products. Therefore, researchers are encouraged to test the proposed propositions further.
Practical implications
Microparticulate salt has been successfully applied to reduce sodium in solid products, being added to the finished product surface. However, there are no studies that report its effectiveness in semisolid and liquid products, such as the butter, in which the salt is added during the product preparation. Thus, this research provides new scientific information to the food industry and research fields, to expand the knowledge of reduced-sodium products development using microparticulate salt with sensory quality.
Originality/value
No studies have evaluated the application of microparticulate salt for semisolid product preparation. Therefore, the findings will support the development of healthy products.
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Tainara Leal de Sousa, Jessyca Pinheiro da Silva, Ariadne Ribeiro Lodete, Daniele Silva Lima, Abner Alves Mesquita, Adrielle Borges de Almeida, Geovana Rocha Placido and Mariana Buranelo Egea
This study aims to analyze the levels of vitamin C, phenolic compounds and antioxidants in baby food. Providing nutritious food to the infants is essential for their growth and…
Abstract
Purpose
This study aims to analyze the levels of vitamin C, phenolic compounds and antioxidants in baby food. Providing nutritious food to the infants is essential for their growth and development. Baby foods are foods prepared from any suitable nutritive material and intended for feeding children after six months of age. The search for foods that meet the nutritional needs of children and that also promote aspects of health has increased on the part of parents.
Design/methodology/approach
A total of 17 different types of baby foods (2 brands) were purchased and the vitamin C content, total phenolic compounds (TPC) and antioxidant activity were determined. The authors also assessed the adequacy of labeling in accordance with regulatory parameters. Data was submitted to analysis of variance, and the means were compared by the Tukey test at 5% probability. Principal component analysis was performed to evaluate the results (phenolic compounds, vitamin C and antioxidant activity) from the multidimensional point of view.
Findings
In general, the labeling of baby foods proved to be within the legislation, but with confusing information for the consumer. BF7-AAPO (apple pulp and juice, papaya and orange juice), BF-BAO (banana, apple juice and oatmeal) and BF-AA (apple pulp and juice) showed the highest vitamin C content (20–28 mg/100 g; p < 0.001). BF-A (apple), BF-B (banana) and BF-AA showed the highest TPC (7–8.2 mg/100 g; p < 0.001). BF-CP (cassava-parsley), BF-PCBCP (potato, carrot, beef and cassava-parsley) and BF-PCBB (potato, carrot, beef and broccoli) showed the highest antioxidant activity (44–48%; p < 0.001). High value of TPC was related to high value of antioxidant activity in baby foods. In conclusion, vitamin C content in the baby foods was different from those reported on the labels and there was a direct relationship between the content of TPC and the antioxidant capability.
Originality/value
The objective of this work was to evaluate bioactive compounds and antioxidant activity in baby foods. So far, few papers have reported on the subject as the authors seek to know about essential nutrients. However, this knowledge is important because these compounds can decrease and/or prevent inflammatory processes in the body.
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Abstract
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Igor Gomes Vidigal, Mariana Pereira de Melo, Adriano Francisco Siqueira, Domingos Sávio Giordani, Érica Leonor Romão, Eduardo Ferro dos Santos and Ana Lucia Gabas Ferreira
This study aims to describe a bibliometric analysis of recent articles addressing the applications of e- noses with particular emphasis on those dealing with fuel-related…
Abstract
Purpose
This study aims to describe a bibliometric analysis of recent articles addressing the applications of e- noses with particular emphasis on those dealing with fuel-related products. Documents covering the general area of e-nose research and published between 1975 and 2021 were retrieved from the Web of Science database, and peer-reviewed articles were selected and appraised according to specific descriptors and criteria.
Design/methodology/approach
Analyses were performed by mapping the knowledge domain using the software tools VOSviewer and RStudio. It was possible to identify the countries, research organizations, authors and disciplines that were most prolific in the area, together with the most cited articles and the most frequent keywords. A total of 3,921 articles published in peer-reviewed journals were initially retrieved but only 47 (1.19%) described fuel-related e-nose applications with original articles published in indexed journals. However, this number was reduced to 38 (0.96%) articles strictly related to the target subject.
Findings
Rigorous appraisal of these documents yielded 22 articles that could be classified into two groups, those aimed at predicting the values of key parameters and those dealing with the discrimination of samples. Most of these 22 selected articles (68.2%) were published between 2017 and 2021, but little evidence was apparent of international collaboration between researchers and institutions currently working on this topic. The strategy of switching energy systems away from fossil fuels towards low-carbon renewable technologies that has been adopted by many countries will generate substantial research opportunities in the prediction, discrimination and quantification of volatiles in biofuels using e-nose.
Research limitations/implications
It is important to highlight that the greatest difficulty in using the e-nose is the interpretation of the data generated by the equipment; most studies have so far used the maximum value of the electrical resistance signal of each e-nose sensor as the only data provided by this sensor; however, from 2019 onwards, some works began to consider the entire electrical resistance curve as a data source, extracting more information from it.
Originality/value
This study opens a new and promising way for the effective use of e-nose as a fuel analysis instrument, as low-cost sensors can be developed for use with the new data analysis methodology, enabling the production of portable, cheaper and more reliable equipment.
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THE catalogue, as a library appliance of importance, has had more attention devoted to it than, perhaps, any other method or factor of librarianship. Its construction, materials…
Abstract
THE catalogue, as a library appliance of importance, has had more attention devoted to it than, perhaps, any other method or factor of librarianship. Its construction, materials, rules for compilation and other aspects have all been considered at great length, and in every conceivable manner, so that little remains for exposition save some points in the policy of the catalogue, and its effects on progress and methods. In the early days of the municipal library movement, when methods were somewhat crude, and hedged round with restrictions of many kinds, the catalogue, even in the primitive form it then assumed, was the only key to the book‐wealth of a library, and as such its value was duly recognized. As time went on, and the vogue of the printed catalogue was consolidated, its importance as an appliance became more and more established, and when the first Newcastle catalogue appeared and received such an unusual amount of journalistic notice, the idea of the printed catalogue as the indispensable library tool was enormously enhanced from that time till quite recently. One undoubted result of this devotion to the catalogue has been to stereotype methods to a great extent, leading in the end to stagnation, and there are places even now where every department of the library is made to revolve round the catalogue. Whether it is altogether wise to subordinate everything in library work to the cult of the catalogue has been questioned by several librarians during the past few years, and it is because there is so much to be said against this policy that the following reflections are submitted.