CALCULATION OF LOSSES OF ACTIVE POWER AND ENERGY IN TRANSMISSION LINES AND TRANSFORMERS, AS A PART OF THE ELECTRICAL DISTRIBUTION POWER NETWORK

The paper inhere discusses the impact of renewable distributed generation sources upon the power and energy losses in electrical distribution power networks where these sources are attached. In addition a set of mathematical expressions to calculate these active power and energy losses are presented with the respective examples and implementation

Емпирично изследване на управлението на услугите на агроекосистемите в България

The study is a report from the second stage of the research project "Management of agro-ecosystem services", funded by the Agricultural Academy - https://maessbg.alle.bg The approach developed during the first stage for analysis, evaluation and improvement of the management system of the agro-ecosystem services in the country has been tested. A survey with agricultural producers identified the size and type of "produced" services of agro-ecosystems of different types, and the dominant forms, factors and efficiency of management of agro-ecosystem services. Primary micro-information was collected from managers of 162 "typical" farms of different legal type, size, production specialization, ecological and geographical location. The main agro-regions and basic agroecosystems (plain, mountainous, protected areas, non-favored areas, etc.) are covered, as well as 12 main specific agroecosystems and their agro-ecosystems - Western Stara Planina, Central Balkans, Danube Plain, Stara Planina, Northeast Fore-Balkans, Struma River Valley, Rhodopes, Pernik Basin, Radomir Field, Sredna Gora, Sub-Balkans, Thracian Lowland and Southeastern Bulgaria. By grouping and summarizing the collected primary information, the structure and volume of agro-ecosystem services in the country and in the main types of agro-ecosystems are identified - geographical, basic and specific ecosystems, subsectors of agricultural production, size and legal type of farming organization. Share of participating producers and degree of participation in storage and supply were used as proxy indicators for production volume of the respective types of holdings. The connection between the main characteristics of farm managers (gender, age, education, farming experience, etc.) and their knowledge and application of the concept of agro-ecosystem services has been established. The main domestic, market, contractual, collective, tripartite, etc. are identified. forms of management of agro-ecosystem services of different types in general and depending on the type of agro-ecosystem and the agricultural producer. An in-depth study of the predominant forms of management of basic agro-ecosystem services such as providing external access to the farm, biodiversity conservation, plant pollination, bioproduction, etc. has been established, and a link with specialization, location, etc. has been established. characteristics of holdings. The effectiveness of the various forms of management of agro-ecosystem services has been established by assessing the direct and additional costs associated with the supply and management of agro-ecosystem services, as well as the direct, additional and indirect effects of their supply. The main behavioral, economic, institutional, natural, etc. are identified. factors that stimulate or limit the "production" of agro-ecosystem services by farmers. The intentions of the agricultural producers related to the protection of ecosystems and ecosystem services in the near future have also been determined. An in-depth analysis of the development and efficiency of organic production as one of the main forms of supply of agro-ecosystem services by Bulgarian farms. A multifaceted analysis of soils has been made as part of Bulgaria's agri-environmental resource, on the example of rural areas in the South Central region. The possibilities for using the sludge from the wastewater treatment plants as a form of agro-eco-service in support of agriculture have been assessed. The use of the customer value category in the management of agro-ecosystem services is analyzed. Summarized conclusions and proposals for improving the approach to scientific analysis and guidelines for improving public policies and forms of public intervention, and individual, business and collective strategies and actions for effective management of agro-ecosystems and services of agro-ecosystems of different types have been prepared

WALOWA (wave loads on walls) : large-scale experiments in the delta flume

Overtopping wave loads on vertical structures on top of a dike have been investigated in several small scale experiments in the past. A large-scale validation for a mild foreshore situation is still missing. Hence the WALOWA experimental campaign was carried out to address this topic. In the present paper the objectives of the WALOWA project are outlined in detail, the model and measurement set-up described and the test program presented. Furthermore, preliminary results featuring a single 1000 irregular waves test of the test program are highlighted. This includes the study of the mild and sandy foreshore evolution by comparing profiles before and after the test execution. The profile measurements are obtained with a mechanical profiler. The wave parameters offshore and at the dike toe are numerically simulated using a SWASH model. The numerical results are validated against the measurements. Finally, the force and pressure time series of the waves impacting against the wall are processed and filtered. The load cell measurements and the time series of integrated pressures are compared to each other and for each impact event the maximum force is derived.Hydraulic Structures and Flood RiskEnvironmental Fluid Mechanic

Холистичен подход за дефиниране, оценяване и подобряване на конкурентоспособността на земеделските стопанства в България

The report presents the results of the first stage of the research project "Competitiveness of agricultural farms in Bulgaria" funded by the Agricultural Academy and implemented by a team from the Institute of Agrarian Economics, UNWE, NBU and IPAZR "N. Pushkarov ”in Sofia. A holistic framework for understanding, evaluating, and improving the competitiveness of agricultural holdings in Bulgaria has been elaborated. The achievements of the interdisciplinary New Institutional Economics, Theory of Economic Organizations, Theory of Competitiveness and other scientific methods such as: study of literature and experience, summary, synthesis, design, comparative and institutional analysis, multicriteria analysis, groupings, discrete structural analysis, value -measuring, qualitative analysis, expert evaluation, survey, Shift-share Analysis, VTOPSIS and statistical analysis, localization analysis, etc. Numerous publications and experience in the country and the world for understanding and assessing the competitiveness of agricultural holdings have been studied. On this basis, a (more) adequate definition of the competitiveness of the farm is given, it is justified that it has four equally important pillars (economic efficiency, financial capability, adaptability and sustainability), and a hierarchical system is developed to assess its level consisting of adequate criteria, indicators and reference values, and an approach to integration and interpretation. The new evaluation system is being experimented with, using survey information from managers of "typical" farms of different types, production specializations and geographical locations. The theoretical bases of business models are summarized and an innovative model of competitiveness of agricultural holdings is developed. An approach to assessing market and factor competitiveness has been adapted and tested in the dairy sector. The regional differences in the competitiveness of agriculture in the EU countries have been identified. The competitive positions and forms of management of alternative farms in the conditions of the Kovid pandemic are assessed. The peculiarities in determining the competitiveness of organic farms are highlighted. The advantages of strategic partnerships and network structures as a tool for increasing the competitiveness of small and medium farms were assessed. The possibilities of the "new" forms of marketing (green, niche, sustainable, etc.) and digitalization to increase the competitiveness of farms are assessed. A regional analysis of agricultural holdings and employees in the South Central region was made. Alternative forms of financing agriculture from banks and leasing companies to improve the competitiveness of farms have been assessed. Conclusions and recommendations for improving public policies and farming strategies have been prepared. The performed activity and the achieved results in terms of volume and quality fully correspond (and exceed) the planned for all tasks. More information can be obtained from the project website https://cfb.alle.bg

Wave impacts on storm walls, a study on scale effects

Low-lying countries such as Belgium and the Netherlands are naturally susceptible to overtopping wave attacks. Coastal regions are therefore facing the threat of such events causing damage to dike-positioned structures and buildings. Research in this filed is often conducted using scaled-down 2D hydraulic physical models, which introduces so called scale effects that can bias the results with regard to measured wave-structure impact forces. This thesis therefore attempts to determine the effects of scaling for post-overtopping wave impacts. To achieve this, large scale physical modelling tests were conducted at Deltares’ Delta flume and compared with a small scale model of similar configuration. A second thesis aim stems from the application of measurement devices in an innovative manner while conducting the large scale tests, and their applicability is assessed here. The model comparison shows that in general the small scale test performs very similarly to its large scale counterpart, and scaling effects did not appear to bias the impact events considerably. This was also observed for the pre-impact flow evolution, where the wave interference mechanisms and resulting bore characteristics were also largely similar. The force-time signal for the largest impacts also is related to the pre-impact mechanisms observed. Classification of the extreme bore impacts according to their impact peak ratio did outline a discrepancy between the two models, which was also linked to the difference in entrapped air pocket impacts.The four measurement instruments assessed are a Terrestrial Laser Scanner (TLS), waterproof action camera(s), optical phase detection probe (OPDP) and a high speed camera mounted behind an opening in the impacted wall. Data from the former two was also used in this analysis and their performance was determined to be good.Coastal and Marine Engineering and Management (CoMEM

Cardiac implantable electronic devices in Bulgaria: results from the electronic registry BG-Pace for 2022

Настоящото проучване представя анализ на дейността по електрокардиостимулация в България през 2022 година на базата на данни от национален регистър на имплантираните пациенти. Материали и методи:              Данните, въведени в регистъра BG-Pace за 2022 година са изследвани ретроспективно. Анализирани са демографски данни на пациентите, типа процедура, типа устройство, режима на стимулация, етиологията, симптомите и ЕКГ образа преди имплантацията. Анализиран е броят имплантации при различните типове устройства и обема дейност на центрове и оператори.               Резултати: За изследвания период са имплантирани 4770 устройства от 45 оператори в 30 центъра. Възрастта на пациентите при имплантацията е била 76 (IQR 69-82, 14-98) години като преобладават пациентите от мъжки пол – 2843 (59,6%). Най-голям брой имплантации са осъществени във възрастовата група 70-79 години. Основен дял заемат антибрадикардните стимулатори - 578,8/милион. От тях системи за физиологична стимулация са били 111 (2,3%). Броят на имплантираните кардиовертер-дефибрилатори е по-висок спрямо предходни периоди и достига 31,9/милион. Имплантациите на системи за ресинхронизираща терапия с функция на дефибрилатор също бележат ръст до 15,9/милион. Значителен ръст се наблюдава и при имплантируемите лууп-рекордери, които достигат до 8,8/милион. Броят имплантации за център е  бил 115,5 (IQR 53-261,3, 3-546), а за оператор – 76,5 (IQR 36,8-154,8, 3-364) устройства. Преобладават имплантациите на двукухинни устройства, чийто дял е 83,1% при АV блок І и ІІ степен, 72,5% при пълен АV блок, 82,6% при нарушения на вътрекамерната проводимост и 66,8% при синдрома на болния синусов възел. Режимите, позволяващи предсърден сензинг демонстрират превъзходство  – 62,4% при всички проводни нарушения. Налице е значимо (Р<0,001) нарастване на дяла на VVІ режима с нарастване на възрастта. Заключение: Националният регистър BG-Pace включва системно въведени клинични, демографски и процедурни данни на имплантираните пациенти. Демонстрира се повишаване на броя на  имплантации в сравнение с предходни периоди като същият остава нисък спрямо средното европейско ниво. The current study analyses the activity on cardiac pacing in Bulgaria in 2022 based on data derived from a national registry of patients with cardiac implantable electronic devices (CIEDs). Materials and methods. Data from the national registry BG-Pace for 2022 was studied retrospectively. Demographic data, procedure and device type, pacing mode, etiology, symptoms, preimplantation ECG, number of implantations, and centre and operator volumes were analyzed. Results: Four thousand seven hundred seventy devices were implanted by 45 operators in 30 centers. Median age was 76 (IQR 69-82, 14-98) years, and male patients were 2843 (59,6%). The most significant number of implantations were carried out in the age group 70-79 years. The most commonly implanted CIEDs were antibradycardia devices - 578,8/million. Of them, conduction system pacing was used in 111 (2.3%). Implanted cardioverter-defibrillators demonstrated a growth compared to previous periods and reached 31.9/million. Cardiac resynchronization defibrillators implantations also shown a growth to 15.9/million. A considerable increase was found with implantable loop-recorders, which reached 8.8/million. Number of implantations per center was 115.5 (IQR 53-261.,3, 3-546), and 76,5 (IQR 36,8-154,8, 3-364) devices per operator. Dual chamber devices were most commonly implanted with a share of 83.1% in AVB I and II degrees, 72.5% in complete AVB, 82.6% in intraventricular conduction disturbances, and in 66.8% in patients with sick sinus syndrome. Pacing modes allowing for atrial sensing were most frequently implanted – 62.4% of all implantations for conduction disturbances. There was a significant increase in the use of VVI mode with increasing age (P<0.001). Conclusion: The national registry BG-Pace includes systematic clinical, demographical, and procedural data for CIED implantations in Bulgaria. There is a growth in the implantation rates compared to previous periods, but they remain lower than the average number for Europe

Cardiac implantable electronic devices in Bulgaria: results from the electronic registry BG-Pace for 2022

Настоящото проучване представя анализ на дейността по електрокардиостимулация в България през 2022 година на базата на данни от национален регистър на имплантираните пациенти. Материали и методи:              Данните, въведени в регистъра BG-Pace за 2022 година са изследвани ретроспективно. Анализирани са демографски данни на пациентите, типа процедура, типа устройство, режима на стимулация, етиологията, симптомите и ЕКГ образа преди имплантацията. Анализиран е броят имплантации при различните типове устройства и обема дейност на центрове и оператори.               Резултати: За изследвания период са имплантирани 4770 устройства от 45 оператори в 30 центъра. Възрастта на пациентите при имплантацията е била 76 (IQR 69-82, 14-98) години като преобладават пациентите от мъжки пол – 2843 (59,6%). Най-голям брой имплантации са осъществени във възрастовата група 70-79 години. Основен дял заемат антибрадикардните стимулатори - 578,8/милион. От тях системи за физиологична стимулация са били 111 (2,3%). Броят на имплантираните кардиовертер-дефибрилатори е по-висок спрямо предходни периоди и достига 31,9/милион. Имплантациите на системи за ресинхронизираща терапия с функция на дефибрилатор също бележат ръст до 15,9/милион. Значителен ръст се наблюдава и при имплантируемите лууп-рекордери, които достигат до 8,8/милион. Броят имплантации за център е  бил 115,5 (IQR 53-261,3, 3-546), а за оператор – 76,5 (IQR 36,8-154,8, 3-364) устройства. Преобладават имплантациите на двукухинни устройства, чийто дял е 83,1% при АV блок І и ІІ степен, 72,5% при пълен АV блок, 82,6% при нарушения на вътрекамерната проводимост и 66,8% при синдрома на болния синусов възел. Режимите, позволяващи предсърден сензинг демонстрират превъзходство  – 62,4% при всички проводни нарушения. Налице е значимо (Р<0,001) нарастване на дяла на VVІ режима с нарастване на възрастта. Заключение: Националният регистър BG-Pace включва системно въведени клинични, демографски и процедурни данни на имплантираните пациенти. Демонстрира се повишаване на броя на  имплантации в сравнение с предходни периоди като същият остава нисък спрямо средното европейско ниво. The current study analyses the activity on cardiac pacing in Bulgaria in 2022 based on data derived from a national registry of patients with cardiac implantable electronic devices (CIEDs). Materials and methods. Data from the national registry BG-Pace for 2022 was studied retrospectively. Demographic data, procedure and device type, pacing mode, etiology, symptoms, preimplantation ECG, number of implantations, and centre and operator volumes were analyzed. Results: Four thousand seven hundred seventy devices were implanted by 45 operators in 30 centers. Median age was 76 (IQR 69-82, 14-98) years, and male patients were 2843 (59,6%). The most significant number of implantations were carried out in the age group 70-79 years. The most commonly implanted CIEDs were antibradycardia devices - 578,8/million. Of them, conduction system pacing was used in 111 (2.3%). Implanted cardioverter-defibrillators demonstrated a growth compared to previous periods and reached 31.9/million. Cardiac resynchronization defibrillators implantations also shown a growth to 15.9/million. A considerable increase was found with implantable loop-recorders, which reached 8.8/million. Number of implantations per center was 115.5 (IQR 53-261.,3, 3-546), and 76,5 (IQR 36,8-154,8, 3-364) devices per operator. Dual chamber devices were most commonly implanted with a share of 83.1% in AVB I and II degrees, 72.5% in complete AVB, 82.6% in intraventricular conduction disturbances, and in 66.8% in patients with sick sinus syndrome. Pacing modes allowing for atrial sensing were most frequently implanted – 62.4% of all implantations for conduction disturbances. There was a significant increase in the use of VVI mode with increasing age (P<0.001). Conclusion: The national registry BG-Pace includes systematic clinical, demographical, and procedural data for CIED implantations in Bulgaria. There is a growth in the implantation rates compared to previous periods, but they remain lower than the average number for Europe

Minimally Invasive Management of Giant Esophageal Polyp - a Case Report

Introduction: The benign tumors of the esophagus are rare disease. Their size has a great variation - from a few centimeters to taking up the whole length of the esophagus. Usually, they present with dysphagia, anemia and in some cases - aspiration or protrusion through the mouth. The polyps are mainly of fibroepithelial origin. Most of them are treated surgically with cervicotomy or esophagotomy.Materials and Methods: We present a case of a 65-year-old male patient with a large 18x5 cm esophageal polyp with an origin from the upper esophagus after the hypopharynx. The preoperative computed tomography angiography excluded the presence of large vessels in the polyp stalk and that helped to establish the surgical strategy - injection of aethoxysklerol at the polyp base and resection with the help of laparoscopic vessel sealer and divider (LigaSureâ„¢). The transoral endoscopic approach was achieved using Weerda diverticuloscope.Results: The polyp was resected successfully. The vessel sealer provided excellent hemostasis and no damage to the surrounding tissues. The only limitation of the transoral approach was due to the large size of the polyp, which had to be extracted via gastrotomy through a 5cm midline laparotomy incision. The postprocedural period was uneventful, liquid food intake was restored on the 2nd postprocedural day and solid food on the 3rd day. The patient was discharged on the fifth day. After one-year follow-up no recurrence was detected. Discussion: Various approaches have been described for the removal of large esophageal polyps, varying from transoral hybrid approach, cervical approach, thoracoscopic approach and even esophagectomy according to the experience of the institution. Due to the benign characteristics of the disease more minimally invasive approach is preferred and it should be offered to the patient.Conclusion: Preoperative staging of the disease is essential to determine the operational approach that will be applied. The LigaSure device can provide safe hemostasis and facilitate the resection of the polyp stalk. The minimally invasive approach even in cases of large esophageal polyp is safe and feasible and the tumor can be easily extracted via small laparotomy and gastrotomy