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The Modeling of Nitrogen Mass Transport in CoCr Alloys
2016
Petraitienė, Akvilė
The kinetics of plasma nitriding of CoCr alloy below temperatures of nitrides formation and mechanisms of nitrogen penetration are analyzed by proposed kinetic modeling in this article. Proposed nitrogen diffusion model is based on the trapping – detrapping (TD) model and developed taking into account the effect of the concentration dependent diffusivity of nitrogen, nitrogen adsorption on the surface of alloy and surface swelling process. The model indicates the influence of chromium atoms to nitrogen atoms diffusivity. The model consists of time and depth dependent diffusion, which is described by a partial differential equation, and it is solved by using Crank – Nicolson finite difference method. By fitting of experimental nitrogen depth profiles, it is shown that nitrogen diffusion coefficient varies with nitrogen concentration according to Einstein-Smoluchowski relation. Nitrogen depth profiles in plasma nitrided medical grade CoCr alloy (ISO 5831 – 12) at T = 400 °C for 1, 4 and 20 hours calculated on the basis of this model are in good agreement with experimental nitrogen profiles. Furthermore, the swelling process is showed and analyzed, derived the dependency of swelling rate on nitriding duration – the swelling rate is inversely proportional to the square root of nitriding duration. The obtained diffusion coefficient value and the swelling process rates satisfy the experimental data form Ref. The derived model explains physical processes during plasma nitriding and allows obtaining nitrogen depth profiles for any requisite nitriding duration.
显示更多 [+] 显示较少 [-]Theoretical Studies of the Vibration Process of the Dryer for Waste of Food
2020
Bulgakov, Volodymyr | Sevostianov, Ivan | Kaletnik, Gryhoriy | Babyn, Ihor | Ivanovs, Semjons | Holovach, Ivan | Ihnatiev, Yevhen
An urgent problem is drying and processing of the wet dispersed waste, obtained in the production of food products, which can then be efficiently used as a fertiliser, for feeding livestock or as biofuel. A new design of a vibrating fluidised bed dryer has been developed, which, with low energy consumption, provides a pre-set productivity and the required final moisture content. The process of vertical oscillations of the body of a vibration dryer, together with the food waste contained in it, is analysed analytically, the necessary equivalent scheme is built, on the basis of which differential equations of the vertical oscillations of the body are compiled, their analytical solutions are obtained, and a numerical calculation is performed on a PC using the developed program. Rational parameters of the vibration dryer, providing vibroboiling of the mass of the food waste, have been determined: the body mass m = 250 ... 510 kg; the debalance mass md = 10… 15 kg; the number of revolutions of the debalance electric motor nd = 1950 ... 2650 rpm ∙ min ∙¹; maximum stiffness of the support springs Cₚ = 8∙10⁵ N∙m–¹; the diameter of the centre of mass of the debalances dd = 0.01 m. In addition, as a result of the thermophysical theoretical and experimental studies of the vibration drying process, the following optimal design and technological parameters of the vibration dryer were obtained: the heat transfer area Sₜ.ₚ.ₙ= 4.15 m²; the radius of the heating pipe rₜ= 0.1 m; the length of the heating pipe lₜ = 3 m; the number of heating pipes nₜ= 50; the heat transfer coefficient Kₚ= 2500; the final temperature of the dried waste tₒ₂ = 100 ºС.
显示更多 [+] 显示较少 [-]A Case-study: Temperature Distribution and Heat Penetration in Steam-air Retort, Using Glass Jars and Retort Pouches
2021
Raits, Evalds | Pinte, Lasma | Kirse-Ozolina, Asnate | Muizniece-Brasava, Sandra
Retort thermal sterilization of canned food is a technology, which allows preserving food products by applying heat on packaged food in retorts (autoclaves) at temperatures up to 121 °C. The thermodynamics of the processes in the retort are influenced by the product stacking method in the basket and packaging material. The aims of this study were: 1) to analyse and compare temperature distribution (TD) and the slowest to heat location in the steam-air retort stacked with glass jars and with retort pouches; 2) to analyse and compare commercial product heat penetration (HP) characteristics in glass jars and retort pouches. Temperature measurements were performed with wireless thermocouples. The come-up time (heating phase) required to achieve in the retort temperature uniformity criteria of ±0.5 °C, is 28 min when the retort is stacked with glass jars, and 24 min when the retort is stacked with retort pouches. Total calculated process time (holding phase), necessary to achieve the sterilization value (F₀ of 3 min), for sample in glass jars was 67 min, but in retort pouches – 62 min. The overall sterilization process time difference between two considered packaging types was 9 min, which is significant amount of time in the context of commercial processing. The study clearly shows the necessity to perform the Temperature Distribution and Heat Penetration study, as each packaging material, stacking method and product will affect sterilization process thermodynamics and, therefore, the overall process time and consequently - the safety of food product.
显示更多 [+] 显示较少 [-]The Influence of Germinated Hull-less Barley Sordough Fermentation Conditions on the Microbiota Development
2021
Kl̦ava, Dace | Poisa, Iveta | Reidzane, Sanita | Kince, Tatjana | Kazantseva, Jekaterina | Traksmaa, Anna
Sourdough plays an important role in quality assurance, especially during developing wholegrain wheat bread products. The value of barley and hull-less barley grains is determined by the low lipid and high carbohydrate (starch and resistant starch) content, balanced amino acid profile, dietary fibre and phenolic compounds. During germination (24 h) the amount of sugar, amino acids and vitamins increase in the grains. Therefore, it could be optimal environment for microbiota growth in sourdough. The goal of the research was to find optimal technological parameters and to study microorganism growth dynamic during the fermentation of sourdough with germinated hull-less barley. The study was performed using three steps of fermentation, with different temperature and time parameters. At each step pH, dynamics of lactic acid bacteria (LAB), yeast-like fungi and total plate count (TPC) growth were determined using standard methods. The results of the study showed that the optimal fermentation conditions for the first stage are 48 h and 26 ± 1 °C, for the second stage 8 h and 26 ± 1 °C and for the third stage 20 h and 28 ± 1 °C. During fermentation of the sourdough, the pH 3.91 is reached, LAB 8.8 log₁₀ CFU g⁻¹, and the yeast-like fungi 8.7 log₁₀ CFU g⁻¹ was determined. Obtained data show that more than 80 bacteria and 50 microscopic fungal species were detected in hull-less barley flour, but after germination their diversity decreased and in the germinated hull-less barley sourdoughs dominated species were Pediococcus pentosaceus.
显示更多 [+] 显示较少 [-]Fault Diagnosis of Low-Power Three-Phase Induction Motor
2016
Gedzurs, Aleksejs
An Induction motor reliability survey at an egg processing plant shows that almost 50% of the total motor failures are fan induction motors. Visual investigations of the faulty fan motors show that the main cause of the induction motor failure is air gap eccentricity. In this study, experimental tests are performed on a 1.1kW three-phase induction motor to detect air gap eccentricity and overheating of the induction motor. Heating tests show that end shield housing temperature reaches 100°C with blocked air flow from the fan, which can reduce the lifespan of the bearing. Dimension measurements of the end shield housing show that the dimensions of both tested motors back-end shields are larger than ISO tolerance grade limit. It leads to a loose fit between the housing and bearing, causing air gap eccentricity. Also, both motor back end shield housing has an out-of-round condition leading to an unbalanced magnetic pull. To detect the air gap eccentricity caused by too loose of a fit between housing bore and bearing, current Park’s vector approach is used. To measure three phase current, Hall Effect current transducers, a digital oscilloscope is used and Matlab software to process the measurement data. Results show that Park’s vector approach can be used to detect the air gap eccentricity caused by too loose a fit between bearing and housing. Therefore, the Park’s vector approach can be used to diagnose air gap eccentricity and analyse the type of the air gap eccentricity.
显示更多 [+] 显示较少 [-]Temperature and weight monitoring of the Apis Cerana bee colony Indonesia
2020
Kviesis, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia). Faculty of Information Technologies. Dept. of Computer Systems | Zacepins, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia). Faculty of Information Technologies. Dept. of Computer Systems | Komasilovs, V., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia). Faculty of Information Technologies. Dept. of Computer Systems | Paramita, A.M., Labtek Indie, Bandung, West Java (Indonesia) | Muhammad, F.R., Labtek Indie, Bandung, West Java (Indonesia)
Remote and automatic monitoring of two Apis Cerana bee colonies was conducted in Indonesia to demonstrate precision beekeeping approach in that region. Successful implementation of the precision beekeeping system includes development of the bee colony monitoring hardware and software for data collection, analysis and visualisation. This paper focuses on development and installation of such systems at the private apiary in Indonesia. For bee colony monitoring at the apiary a developed monitoring unit was used, which is based on ESP microchip, and for the data storage SAMS data warehouse was used. The monitoring results showed that the choice of the location of the temperature sensor is important, as the temperature at the hive sides changes synchronously with the outside temperature. Also, feedback from the beekeeper is collected to further improve the system and monitoring process. This research is conducted within the SAMS – Smart Apiculture Management Services project, which is funded by the European Union within the H2020-ICT-39-2016-2017 call and with close collaboration with the local private beekeeper. To find out more, visit the project website https://sams-project.eu/.
显示更多 [+] 显示较少 [-]Effect of storage period on acid value and sensory attributes of puffed wheat grains ‘Badyrak vanilla’ and ‘Badyrak with whey’
2023
Konkubaeva, Nurzat | Kulmyrzaev, Asylbek | Deydiev, Anarseit | Radenkovs, Vitalijs | Galoburda, Ruta
Puffed grains made from whole wheat, corn or rice grains are ready-to-eat breakfast cereals that do not require additional preparation. Two recipes for puffed grain coatings were developed in the previous studies. Sunflower oil was used in the coating, which may affect storage stability. Due to lipid hydrolysis, free fatty acids may be released, causing rancid off-flavour. The aim of this study was to determine the changes in the acid value of lipids and sensory attributes of sweet-coated puffed wheat grains ‘Badyrak vanilla’ (BV) and ‘Badyrak with whey’ (MC) depending on temperature during their eight-month storage. The products were packaged in metallised polypropylene pouches, 30 g each. The acid value was studied monthly at different storage temperatures (20 ± 2 °С and 4 ± 2 °С). In puffed wheat grain products, 65% of fatty acids are polyunsaturated, 25% monounsaturated, and 10% saturated. The high proportion of unsaturated fatty acids over saturated makes oil more susceptible to oxidation. Literature studies and sensory evaluation of puffed wheat grains allowed setting a limiting acid value at 4.0 mg KOH gE−1 lipids. The increase in acid value was storage temperature dependent. Thus, the acid value exceeded the established limit in the fifth month for MC and the sixth month for BV when stored at 20 ± 2 °С. At the same time, noticeable changes in puffed wheat grain flavour were observed. The temperature coefficient (Q10) for MC was 2.0, whereas for BV it was 1.5, indicating that the acid value increase in MC was more affected by temperature than that in BV.
显示更多 [+] 显示较少 [-]The quality function in determining the effectiveness of example bioeconomics tasks
2022
Levkin, Artur | Abuselidze, George | Berezhna, Natalija | Levkin, Dmytro | Volkova, Tetiana | Kotko, Yana
The aim of the publication is to develop theoretical and methodological foundations and practical recommendations for determining the efficiency of biotechnological processes with the subsequent justification of technical parameters to ensure a high level of viability of bio-objects. In the course of the conducted scientific research, the criteria of quality function were defined and formalised, in accordance with which the conditions of biotechnological processes of laser division of embryo were formulated as a single case in the realisation of the economic mechanism of biotechnology. This makes it possible to ensure a high level of cattle (cattle) productivity, reduce the time for the reproduction of livestock and reduce the costs of movement, trade and transportation of cattle. The quality function of the biotechnological process of laser division of embryo is formulated on the basis of criterion of non-exceeding of the temperature field in cells of blastomeres and the predetermined acceptable value that allowed one to take into account the main parameters and to propose the criterion of biotechnological process optimisation. As a promising task for the development of the bioeconomy as an economic mechanism in implementing biotechnologies, the necessity of determining the quality function by formalising the integral indicator of efficiency has been established, This enables one to ensure a high level of commercialisation of biotechnologies, to increase the productivity of agricultural animals, and to suggest alternative methods for the quick renewal of livestock.
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