A self-consistent kinetic model for droplet heating and evaporation

A new kinetic model for heating and evaporation of Diesel fuel droplets is suggested. The model is based on the introduction of the kinetic region in the immediate vicinity of the heated and evaporating droplets, where the dynamics of molecules are described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. Diesel fuel is approximated by n-dodecane or a mixture of 80% n-dodecane and 20% p-dipropylbenzene. In both cases, the evaporation coefficient is assumed equal to 1. The values of temperature and vapour density at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour (or vapour components) in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions should be equal. Initially, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following the above-mentioned procedure, are used to calculate the corrected values of hydrodynamic heat and mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region etc. It is shown that this process quickly converges for the cases analysed in the paper, and it leads to self-consistent values for both heat and mass fluxes. The model is applied to the analysis of heating and evaporation of Diesel fuel droplets with initial radii and temperature equal to 5 μm and 300 K, immersed into gas with temperatures in the range 800–1200 K and pressure equal to 30 bar. It is shown that in all cases the kinetic effects lead to a decrease in droplet surface temperature and an increase in the evaporation time. The kinetic effects on the droplet evaporation time are shown to increase with increasing gas temperatures. Publisher statement: NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Heat and Mass Transfer. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Heat and Mass Transfer, [79, (2015)] DOI: 10.1016/j.ijheatmasstransfer.2015.10.039 © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0

Methodology for Training Teachers in Basic and Specific Computer Skills

This article describes methodology for training teachers in Maths, Physics, Astronomy and Professional subjects in basic and specific computer skills

Implementing AI technologies for enhanced e-commerce strategies

openThe emergence growth of the electronic commerce (e-commerce) industry during recent decades transformed business processes. It, firstly, involves the need and capability to collect and process huge amounts of data on consumer behaviour and internal company operations to reach a performance increase. To archive it effectively, e-commerce industry is implementing AI technologies for various functions including price maintaining, recommendation systems, personalized and voice assistance, supply chain optimization and many more. AI empowered such e-commerce tools as personalized systems, improved A/B testing, immediate customer support that evidently led to data-driven strategies adoption and structural business changes. This study aimed to analyze how AI algorithms such as Machine Learning, Natural Language Producing (NLP), etc. are used for e-commerce tools in order to boost performance metrics. Through the deep literature review the integrative map of AI technologies in various e-commerce processes was created. Additionally, the article explored case studies from e-commerce companies and firms providing AI solutions for businesses. Nowadays, the rapid development of both AI and e-commerce creates not only more opportunities but also challenges, making the integration of AI essential for businesses aiming to have a competitive position in the market.The emergence growth of the electronic commerce (e-commerce) industry during recent decades transformed business processes. It, firstly, involves the need and capability to collect and process huge amounts of data on consumer behaviour and internal company operations to reach a performance increase. To archive it effectively, e-commerce industry is implementing AI technologies for various functions including price maintaining, recommendation systems, personalized and voice assistance, supply chain optimization and many more. AI empowered such e-commerce tools as personalized systems, improved A/B testing, immediate customer support that evidently led to data-driven strategies adoption and structural business changes. This study aimed to analyze how AI algorithms such as Machine Learning, Natural Language Producing (NLP), etc. are used for e-commerce tools in order to boost performance metrics. Through the deep literature review the integrative map of AI technologies in various e-commerce processes was created. Additionally, the article explored case studies from e-commerce companies and firms providing AI solutions for businesses. Nowadays, the rapid development of both AI and e-commerce creates not only more opportunities but also challenges, making the integration of AI essential for businesses aiming to have a competitive position in the market

Expression of the KNOTTED HOMEOBOX Genes in the Cactaceae Cambial Zone Suggests Their Involvement in Wood Development

The vascular cambium is a lateral meristem that produces secondary xylem (i.e., wood) and phloem. Different Cactaceae species develop different types of secondary xylem; however, little is known about the mechanisms underlying wood formation in the Cactaceae. The KNOTTED HOMEOBOX (KNOX) gene family encodes transcription factors that regulate plant development. The role of class I KNOX genes in the regulation of the shoot apical meristem, inflorescence architecture, and secondary growth is established in a few model species, while the functions of class II KNOX genes are less well understood, although the Arabidopsis thaliana class II KNOX protein KNAT7 is known to regulate secondary cell wall biosynthesis. To explore the involvement of the KNOX genes in the enormous variability of wood in Cactaceae, we identified orthologous genes expressed in species with fibrous (Pereskia lychnidiflora and Pilosocereus alensis), non-fibrous (Ariocarpus retusus), and dimorphic (Ferocactus pilosus) wood. Both class I and class II KNOX genes were expressed in the cactus cambial zone, including one or two class I paralogs of KNAT1, as well as one or two class II paralogs of KNAT3-KNAT4-KNAT5. While the KNOX gene SHOOTMERISTEMLESS (STM) and its ortholog ARK1 are expressed during secondary growth in the Arabidopsis and Populus stem, respectively, we did not find STM orthologs in the Cactaceae cambial zone, which suggests possible differences in the vascular cambium genetic regulatory network in these species. Importantly, while two class II KNOX paralogs from the KNAT7 clade were expressed in the cambial zone of A. retusus and F. pilosus, we did not detect KNAT7 ortholog expression in the cambial zone of P. lychnidiflora. Differences in the transcriptional repressor activity of secondary cell wall biosynthesis by the KNAT7 orthologs could therefore explain the differences in wood development in the cactus species

Kinetic and MD modelling of automotive fuel droplets heating and evaporation: recent results

[EN] Recent results of the investigation of kinetic and molecular dynamics (MD) models for automotive fuel droplet heating and evaporation are summarised. The kinetic model is based on the consideration of the kinetic region in the close vicinity of the surface of the heated and evaporating droplets, where the motion of molecules is described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region away from this surface. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. A new self-consistent kinetic model for heating and evaporation of Diesel fuel droplets is briefly described. The values of temperature and vapour densities at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour components in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions are equal. At first, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following this procedure, are used to calculate the corrected values of hydrodynamic heat and species mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region. It is shown that this process quickly converges and leads to self-consistent values for both heat and mass fluxes. Boundary conditions at the surface of the droplet for kinetic calculations are inferred from the MD calculations. These calculations are based on the observation that methyl (CH3) or methylene (CH2) groups in n-dodecane (approximation of Diesel fuel) molecules can be regarded as separate atom-like structures in a relatively simple United Atom Model. Some results of the application of quantum chemical methods to the estimation of the evaporation/condensation coefficient are discussed.The authors are grateful to the EPSRC (UK) (grants EP/K005758/1, EP/K020528/1 and EP/M002608/1), the Royal Society (UK) (grant IE 160014) and the Russian Foundation for Basic Research (grant No. 17-08-01274) for their financial support.Sazhin, S.; Shishkova, I. (2017). Kinetic and MD modelling of automotive fuel droplets heating and evaporation: recent results. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 1076-7082. https://doi.org/10.4995/ILASS2017.2017.4593OCS1076708

THE ROLE OF SOCIAL FARMING FOR SUSTAINABLE RURAL DEVELOPMENT IN BULGARIA

The concept of social farming has gained wide popularity in Bulgaria over the last decade. A number of authors emphasize the importance of this concept for social inclusion and economic empowerment of vulnerable groups of society. Social farming contributes to increasing the level of social capital of the representatives of these groups, provides employment and allows them to become independent economic units. The aim of the study is to show the potential of social farming for achieving sustainable results in the rural areas of Bulgaria, based on the analysis of a network of organizations implementing an integrated model for small business support among disadvantaged families. The study applies social network analysis and case study methods. The results confirm the importance of the concept in addressing major rural problems. Some challenges for social farming have been outlined. Conclusions and recommendations have been made on policies in the area concerned

The influence of acid rain and drought on early growth and development of jack pine and balsam poplar

The influence of "acid rain" (watering with tap water acidified to pH 3.0 ) and drought on jack pine seedlings and balsam poplar cuttings growing in two different soil types was studied in a short-term greenhouse experiment. Changes in soil chemistry were assessed and a number of growth parameters and physiological processes measured. Irrigation with "acid rain" led to rapid soil acidification. It resulted in decreased soil pH, cation exchange capacity and base saturation, and altered concentrations of the basic exchangeable ions; the level of Al’” increased, while the levels of Ca*', Mg”and K’ decreased. There was a slight decrease in total soil organic matter and a slight increase in soil nitrogen. Drought generally enhanced the adverse effects of the soil acidification process. “Acid rain" had a beneficial effect on seedling and cutting growth and development. Height and diameter growth, development of root surface area, production of aboveground and belowground biomass were stimulated by "rain" with pH 3.0. Seedlings and cuttings watered with "acid rain" also had lower water saturation deficit, lower diffusive resistance and higher transpiration rates. Changes in leaf chlorophyll fluorescence indicated slight stimulation of photosynthesis. Drought reduced seedling and cutting growth and development, but "rain" with pH 3.0 significantly reduced these adverse effects. Both tree species responded in a similar way to the stress factors. Plants performed better in the lighter soil because of better growth conditions. For early tree growth and development, "acid rain" was not directly harmful even when combined with drought

LOCAL ACTION GROUPS AND RURAL DEVELOPMENT IN BULGARIA- CHALLENGES AND PROSPECTS

Over the last decade, local action groups (LAGs) in Bulgaria have become key organizations supporting the implementation of projects important for rural development. Prerequisites for this are the unique characteristics of the LEADER/CLLD approach, which allow empowerment of the population, capacity building combined with providing access to financial resources, as well as building trust and accumulation of social capital. Since the beginning of the application of the approach in the country, LAGs have been facing some difficulties, but at the same time the opportunities for attracting funds to support a wide range of initiatives at the local level are expanding. In this regard, the aim of this study is based on the analyses of the activities of LAGs in the country, to outline the challenges facing these organizations and to reveal their potential for sustainable development of rural areas. The case study method is applied. The results of the study show a significant potential of LAGs to accelerate the socio-economic processes in rural areas

IMPLEMENTATION OF COMMUNITY – LED LOCAL DEVELOPMENT STRATEGIES - EVIDENCE FROM SOUTHERN BULGARIA

The LEADER approach/ Community Led - Local Development (CLLD) is one of the most effective tools for rural development at EU level. It enables empowerment of the population, involving all stakeholders in the decisionmaking process. The built trust and the growing role of the Local Action Groups (LAGs), through which the approach is applied, are a prerequisite for LEADER/ CLLD to become a key instrument for tackling the challenges facing the rural areas of Bulgaria. The aim of the study is, based on the analysis of the main factors influencing the results of the implementation of integrated strategies, to outline the opportunities for increasing the number of supported initiatives, as well as to formulate recommendations in the respective field. The study encompasses 34 LAGs operating on the territory of Southern Bulgaria. The results of the regression analysis reveal the following main factors determining the number of supported initiatives under the local development strategies: the experience of the LAGs, the type of strategy (single-fund or multi-fund support) and the ongoing communication with relevant government agencies