Use of a Secondary Current Sensor in Plasma during Electron-Beam Welding with Focus Scanning for Process Control

We consider questions of building a closed-loop focus control system for electron-beam welding. As a feedback signal, we use the secondary current in the plasma that forms above the welding zone. This article presents a model of a secondary current sensor in plasma during electron-beam welding with focus scanning. A comparison of modeled results with experimental data confirms the adequacy of the model. We show that the best results for focus control are obtained when using phase relationships rather than amplitude relationships. We outline the principles for building an EBW focus control system based on parameters of the secondary current in plasma. We simulate the work of a control system’s circuits and demonstrate the stability of the synthesized system. We have conducted pilot tests on an experimental prototype

MANAGEMENT AND CONTROL OF AGRILUS AURICHALCEUS REDT. (COLEOPTERA: BUPRESTIDAE) IN BIOLOGICAL RASPBERRY PRODUCTION

The study was carried out in а raspberry plantation (2013-2015) in the experimental field of the Institute of Agriculture – Kyustendil. The purpose of this study is to investigate the effect of organic fertilizer application on the stock larvae of Agrilus aurichalceus and population management, using biological plant protection products. According to the results of this study, it has been proved that fertilizing with organic fertilizers has a reductive effect on the survival of the A. aurichalceus population and does not affect the population of the larval endoparasitoid Ttrastichus heeringi in the cultivars Willamette and Lyulin. The relationships between A. aurichalceus and T. heeringi in the conditions of organic raspberry production have been studied. The established degree of parasitism of the larvae by T. heeringi (32.7-68.4%) is capable of reducing and controlling the population of A. aurichalceus in the Willamette without chemical control. Two treatments with bioinsecticides have been carried out for the protection of plants from cultivar Lyulin due to a significantly lower degree of parasitism (18.1-50.0%). The most effective insecticides to the control of adults of A. aurichalceus have been identified: Pyrethrum FS EC-0.05% and NeemAzal®-T/S - 0.3 %. The adult control scheme involves two treatments with bioinsecticides of infested shrubs. The first treatment should be done during the buttoning, the second treatment during the mass flight of beetles (only at an established density of 3-4 beetles/m2)

Importance of optical microscopic investigation in provenance studies and quality characteristics of both historical and natural lower globigerina building limestone of Malta

Acknowledgements: This study is related to the realization of a Geological Institute project “Sedimentological study of the Lower Globigerina Limestone for determination of its provenance and assessment of its resistance as a building material of Historical Monuments in Malta”.Several megalithic architectural structures dating to the Neolithic Period as well as many early Baroque buildings were constructed from limestone extracted through open-pit mining from the Lower Globigerina Limestone of the Maltese Islands (Bianco, 2018). The Lower Globigerina Limestone Member is the oldest member of the Globigerina Limestone Formation, widely cropping out in the Maltese Archipelago. It is composed of massive, pale yellow in colour limestone that contains tests of globigerinid planktonic forminifera (Pedley, 1974). Limestone quarried from this member has been used as a building stone since time immemorial (Bianco, 2017). Being soft and porous and constantly exposed to atmospheric influences and weathering, the subsequent deterioration of this limestone significantly damages historical monuments. Different methods are used to study its properties, one of which is optical microscopic investigation (thin-section analysis) (Bianco, 2017, 2018). The objective of thin-section analysis is to investigate the texture, porosity and permeability, important properties of a given limestone, which have a bearing on its durability and weathering characteristics. Such investigation is particularly useful when rocks are fine-grained or strongly weathered (Dreesen et al., 2006).peer-reviewe

Multiresponse Robust Engineering: Case with Errors in Factor Levels

2000 Mathematics Subject Classification: 62J05, 62J10, 62F35, 62H12, 62P30.The model-based robust approach for improving the quality of the process is successfully applied to different industrial processes. In the case of multiple correlated responses the estimation of the mean and variance models of the quality characteristics in production conditions, taking into account the correlation between the multiple responses, together with the heteroscedasticity of the observations due to errors in the factor levels is considered at multivariate regression fit, robust engineering modeling and the optimization stages. The application of the proposed method gives the possibility to use raw industrial data for mean and variance models estimation and leads to reduction of the predicted variance of the responses in production conditions. The proposed approach is applied for electron beam melting and refining experiments

MONITORING OF POTATO CYST NEMATODES (GLOBODERA SPP.) IN SOUTHWEST BULGARIA

The potato cyst nematodes, Globodera pallida and Globodera rostochiensis, can cause significant economic damage to potato production and their conduct is a difficult process. They are quarantine pests for Europe, which are regulated by different directives specific to different regions. The main objective of the study was to provide data of the determination of the spread of potato cyst nematodes in Southwest Bulgaria in order to limit their further dissemination outside the infected areas. In the period 2015-2016, the monitoring of potato cyst nematodes was carried out in six major potato-producing regions in Bulgaria (Samokov, Pernik, Kyustendil, Pazardzhik, Blagoevgrad and Smolyan). The monitoring has covered seed production areas and potato areas intended for human consumption and/or for processing. The results confirm the presence of both species in the observed potato-growing areas. The distribution and density of nematodes of the genus Globodera varies between regions. G. rostochiensis was the most common species in all areas. The species was found by itself in a higher level than in joint populations of G. pallida

Physical Activity and Use of Electronic Devices in Medical College Students

The development of technology and its widespread application in everyday life is leading to a decrease in physical activity for people of all age groups. The COVID-19 pandemic has also contributed to limiting people's activities.This paper aims to investigate the frequency of electronic device use and the physical activity levels of medical college students. To achieve the objective, we conducted a survey using Google Forms. Forty-two students from the courses of rehabilitation and dental technician at the Medical College, Medical University of Varna, participated. The questionnaire included questions about physical activity, sports activities, awareness of the impact of reduced physical activity on health, and the health problems that e-dependence leads to. The results are presented using tabular and graphical methods as a convenient overview of the data used.The study found that the majority of the subjects lead a sedentary lifestyle and spend a large portion of their time using various electronic devices. Students' awareness of the harmful effects of electronic devices on their health is not conducive to increasing their physical activity

Oxfordian to Valanginian palaeoenvironmental evolution on the western Moesian Carbonate Platform : a case study from SW Bulgaria

Three sections (Rebro, Lyalintsi and Velinovo) of the Upper Jurassic-Lower Cretaceous carbonate sequences from the Lyubash unit (Srednogorie, Balkanides, SW Bulgaria) have been studied for elucidation of biostratigraphy and palaeoenvironmental evolution. Palaeontological studies of foraminifera, supplemented by studies of calcareous dinoflagellate cysts and corals, enabled the determination of the Oxfordian-Valanginian age of the analysed sequences. They were deposited on the Dragoman Block (western part of the Moesian Platform), and during Mid-Late Cretaceous included to the Srednogorie. A possible Middle to Late Callovian age of the lowermost part (overlying the Bajocian-Lower Bathonian Polaten Formation) of the studied sections assumed till now has not been confirmed by the present studies. Eleven facies have been distinguished and attributed to depositional environments. Marine sedimentation on a homoclinal ramp started in the Oxfordian and till the Early Kimmeridgian - in all three sections - was dominated by fine-grained peloidal-bioclastic wackestones to grainstones. Since the Late Kimmeridgian, when a rimmed platform established, facies pattern underwent differentiation into (i) the inner platform (lagoon and tidal flat facies) - only in Velinovo, (ii) reef and peri-reef facies/bioclastic shoals - mainly in Lyalintsi, and (iii) platform slope - mainly in Rebro. Sedimentation generally displays a shallowing-upward trend. Two stages in evolution of the rimmed platform are postulated. The mobile stage lasting till the Tithonian/Berriasian boundary was followed by a more stable stage in the Berriasian to Valanginian time. Reefs are developed mainly as coral-microbial biostromes, lower coral bioherms or coral thickets, in the environment of moderate energy and sedimentation. They contain highly diversified corals (72 species). Micro- bialites contributed to the reef framework, but they never dominated. Locally, microencrusters and cement crusts formed important part of reefal framework. During the mobile stage of the platform evolution a relative sea-level rise interrupted reef development, as evidenced by intercalations of limestones with Saccocoma. During the second stage high carbonate production and/or regressive eustatic events, not balanced by subsidence, decreased accommodation space, limiting reef growth and enhancing carbonate export to distal parts of the platform

Survey Of The Necessity For Improving The Quality Of Health Care Training

The globalization of processes poses the problem of the quality of training of health care professionals in the higher education institution. The teaching process at the higher school has the important social task of preparing specialists capable of carrying out quality professional work with the virtues built up, needed for the daily professional activity.The actuality of the research problem is determined by the need to improve the quality of health care education in the higher school. This requires an adequate assessment of the professional training of future medical specialists, in accordance with changing demographic processes, morbidity, chronic disease and human attitudes towards his or her own health as its highest value.The purpose of the scientific communication is to reveal and outline the need to improve the quality of health care education at the higher school.Tasks of the survey are: to examine the need to improve the quality of health care education in the higher education institution; to reveal the role of higher education; to investigate the effectiveness and relevance of health care education in the higher school; to determine the degree of satisfaction with their performance.The methods used in the research are questionnaire survey, programmed interview, purposefully included observation and pedagogical experiment. Subject of the survey is the necessity to improve the quality of healthcare education in the higher school with the students of the specialty "nurse" at the Medical University - Varna, Sliven Affiliate.Object of the survey is the process and conditions under which the need to improve the quality of healthcare education is being studied.   The analysis of the results has led to the conclusion that it is necessary to periodically increase the quality of healthcare education, in line with the growing needs of the population for proper and timely health care. This requires good organization and management of the learning process; provision of active and planned learning activity; acquiring of professional and moral knowledge, skills and competencies; formation of professionally significant personal qualities of the medical specialist