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Abstract

The availability of freshwater is increasingly becoming an international concern because of the increase in population and the diminishing forest area as a source of water, leading to a freshwater crisis. The coastal and swamp areas abound in water, but humans cannot consume it due to the quality. One effort that can be done in overcoming this problem is by treating existing raw water with solar distillation methods. However, the main obstacle faced in this method is the intensity of sunlight that is not stable throughout the day so that the productivity of distilled water is disrupted. Using the appropriate phase change material (PCM) is expected to make the distillation process smoother and increase the production of pure water. In this study, myristic acid was used as PCM in double slope solar distillation system. Through observation, it was obtained that the average water temperature in the basin equaled to 42.5 °C while the melting point of the myristic acid was 58 °C. This shows that the use of myristic acid as an energy storage through phase change process does not occur. Therefore, the use of myristic acid as PCM for increasing the productivity of solar distillation in these experiments is not effective because the melting point of PCM is higher than water temperature in the basin. Therefore, material with a phase change temperature below 42.5 °C is more appropriate to use in these conditions.

Open access

Abstract

Virtual machine (VM) management is a fundamental challenge in the cloud datacenter, as it requires not only scheduling and placement, but also optimization of the method to maintain the energy cost and service quality. This paper reviews the different areas of literature that deal with the resource utilization prediction, VM migration, VM placement and the selection of physical machines (PMs) for hosting the VMs. The main features of VM management policies were also examined using a comparative analysis of the current policies. Many research works include Machine Learning (ML) for detecting the PM overloading, the selection of VMs from over-utilized PM and VM placement as the main activities. This article aims to identify and classify research done in the area of scheduling and placement of VMs using the ML with resource utilization history. Energy efficiency, VM migration counts and Service quality were the key performance parameters that were used to assess the performance of the cloud datacenter.

Open access

Abstract

Due to recent changes in the labour market, recruitment and retaining employees have become more important than ever. Research dealing with the appearance of new generations in the labour market has found that they are less loyal to their employers, have high demands, and the key factors that they consider when choosing a job are salary, career opportunities, working environment, and work-life balance. As numerous studies in recent years have proved the importance of a healthy lifestyle in the context of labour, the question has arisen whether opportunities for sport participation and services supporting the well-being of employees have an influence on young people when they are seeking employment. We carried out an online survey to find out what students of the University of Debrecen think about the issue. The results were in line with the findings of previous studies, that is, young people look for high salaries, good working conditions, work-life balance and career opportunities when choosing a job. However, respondents did not identify sports opportunities and well-being benefits as major factors Yet, we found significant differences between different groups in terms of preference of particular factors, depending on sex, marital status, and whether someone does physical exercises regularly, and whether someone works while attending a university course or not.

Open access
International Review of Applied Sciences and Engineering
Authors: Adebayo Surajudeen Adekunle, Adekunle Akanni Adeleke, Peter Pelumi Ikubanni, Peter Olorunleke Omoniyi, Tajudeen Adelani Gbadamosi, and Jamiu Kolawole Odusote

Abstract

Heat treatment industries require various quenching media to improve the properties of the materials to be quenched. Petroleum based mineral (PBM) oil, a non-biodegradable oil, is popular amongst others quenchants in heat treatment processes. Recently, biodegradable oils mostly in their raw, unblended and unbleached forms have been employed for quenching of various engineering materials. Therefore, the present study examined the effects of some selected bio-quenchants in blended raw (BR) and blended bleached (BB) forms on the mechanical properties and microstructure of solution heat treated aluminum (Al)-alloy. Edible vegetable oil (70% by volume) was blended with 30% by volume of jatropha oil to form the bio-quenchant oils. Another set of bio-quenchants were formed by bleaching the raw oils before mixing so as to reduce the oxidation level and contaminations in the oil. The Al-alloy is solution heat treated at 500 °C and soaked for 15 min in an electric muffle furnace before quenching in the various established bio-quenchants. Results showed that samples treated in blended raw melon (BRM) oil have higher tensile strength of 151.76 N/mm2 while samples quenched in blended bleached melon (BBM) oil have higher hardness value of 61.00 HRC. In accordance to the results obtained the bio-quenchants were found to be effective replacement to the PBM oil.

Open access

Abstract

The article highlights the worldwide dissemination of precision agriculture scientific researches published from the period of 1996–2018, data gathered in the Scopus citation database, using the science mapping method. The findings show that there is a constant rise in the number of publications in precision agriculture. The USA is not only leading in the adoption of precision agriculture technologies but also in the publication of papers, accompanied by China placed in second place. The most frequent keywords highlighted the main topics authors concentrated on more, and the national affiliation of most cited papers was the USA. The main prominence and contributions of the results present scientific research trends in precision agriculture in the last two decades, and demonstrate the main countries, authors and organizations who have contributed, and were more productive in this area.

Open access

Abstract

The main idea of the current paper consists in introducing the fractional order calculus in a control system. To control the system, an adaptive control technique with reference model is used. The fractional order models for the plant and reference model are obtained. To achieve the performances imposed by the fractional order reference model, a fractional order adaptive control law is proposed, which is a combination of two methods (MIT and Lyapunov stability). The original contribution in this paper is the use of fractional order calculus in the combined MIT and Lyapunov stability method and showing the dynamic behavior of the system. Several simulations are used to emphasize the effectiveness and benefits of the proposed method.

Open access

Scope of the study was to find more effective N fertilisation doses and applications to reach not only higher quantity but better quality grains as well as to be able to help preserving the continuity of feed and food quality improvement, since wheat is one of the most consumed crops all over the world.

Samples of winter wheat (Triticum aestivum L.) varieties harvested from the experimental field of the Szent István University in two consecutive crop seasons had been examined in the laboratory of the Crop Production Institute. Effects of nitrogen (N) application on the performance of grain protein were tested. Five high quality winter wheat varieties were studied regarding grain quality traits affected by applying undivided and split doses of N. The evaluated samples show that increasing doses of N topdressing and increasing time of application have beneficial effects on the yield and the value of protein content. Wheat grain protein value ranged between 9.9% of the untreated Mv Karéj and Alföld, where the 120+40 kg ha-1 N was applied resulting in the highest value of 16.0%. Similarly, the gluten values among untreated and N applied plots were in a wide range. Mv Karéj had the lowest wheat gluten value on untreated plot with 18.4% and Alfold had the highest value with 36.8% on the plot where the 120+40 kg ha-1 N was applied. There were no significant changes recorded on test weight and thousand kernel weight. In the case of baking quality, there were significant differences between varieties. The best records were obtained in the case of Mv Toborzö followed by Mv Karéj.

Open access

Medium chain fatty acids are candidates of partial sulphur dioxide replacement in wine, as a solution to the growing consumer concerns about chemical additives. In botrytised sweet wine specialties, large amount of sulphur dioxide addition is one of the effective practices to stop alcoholic fermentation. Increasing medium chain fatty acid levels up to 80 mg l-1 was tested as a sole inhibitor on solid agar surface. S. bacillaris seemed to be the most sensitive, S. cerevsisiae and S. bayanus were more tolerant, while Z. bailii showed the highest tolerance. Then, increasing medium chain fatty acid levels up to 40 mg l-1 combined with 100 mg l-1 sulphur dioxide was introduced into a Tokaj Essence under refermentation. After 56 days, the highest dosage had pronounced effect on the yeast population, but the refermentation was not inhibited completely. Medium chain fatty acids have varying inhibitory effect on botrytised wine-related yeasts, moreover, it could be used effectively in media with high ethanol content, unlike Tokaj Essence.

Open access
Acta Alimentaria
Authors: J.A. Pino, E. Sauri-Duch, O. Sosa-Moguel, C.A. Can-Cauich, V.M. Moo-Huchin, and L. Cuevas-Glory

An aroma distillate with the odour note described as ‘fresh Habanero chilli pepper' was obtained from hydrodistillation of the fruit. GC-MS analysis of the volatile constituents from the aroma distillate allowed the identification of 100 compounds, most of them esters followed by aldehydes, alcohols, terpenes, ketones, and acids. Encapsulation process of the aroma distillate by spray drying was optimised using response surface methodology. Independent variables were inlet air temperature (150-200 °C) and carrier (maltodextrin 10 DE and gum arabic in 2:1 ratio) content (10-20% wb), while response variables were powder moisture and volatiles retention. Moisture content of the powder varied inversely proportional to the air temperature, while the volatile retention was directly related. Retention of volatiles in the powder increased when the carrier content increased, while this factor negatively affected moisture content. Based on the optimisation model of the response variables, the powder with the highest flavour quality was obtained with an air inlet temperature of 200 °C and 20% wb carrier content, with 4% moisture content and 88.6% volatiles retention.

Open access

The aim of the study was the identification and characterisation of coagulase-positive Staphylococcus bacteria obtained from food matrices by mass spectrometry and molecular methods. A total of 46 coagulase-positive Staphylococcus isolates were collected from different foodstuffs. The Staphylococcus isolates were identified by MALDI-TOF MS and confirmed by the presence and sequence analysis of the Staphylococcus protein A gene. Staphylococcal enterotoxin genes were also investigated by multiplex PCR. Based on the identification of strains by the MALDI-TOF MS technique and spa-typing, all strains were identified as Staphylococcus aureus. Based on their MS peak profiles, the isolates matched the spectra of three S. aureus reference strains in the Bruker MALDI Biotyper database, with identification scores higher than 1.999 in the case of all 46 (100%) isolates. The isolates showed great genetic variability. Twenty spa types were identified, from which most lineages are capable of colonizing humans. Fifty percent of the strains harboured at least one of four enterotoxin genes (seg, seh, sei, and ser), but none of the classical enterotoxin genes could be detected.

Open access