Analysis of current and voltage harmonics introduced by the drive systems of a bucket wheel excavator

Purpose. The quality of electricity is a problem of major interest, making it necessary to analyze the factors and causes that result in the worsening of the electric energy quality. An important aspect of electricity quality is the introduction of current and voltage harmonics in the alternating current network by non-linear consumers. The paper analyzes the deforming regime introduced by the drive systems of a bucket wheel excavator within a technological line at an open pit mine. Methods. The paper presents the measurements of power quality in a laboratory experimental study and measurements of an upgraded technological line at a lignite open pit. In this sense, the present the study of a distorting regime introduced by the drive systems formed from a static frequency converter and an asynchronous motor, as well as the results of quality power measurements introduced by the drive systems in the electric network. Findings. The paper presents analysis of the voltage and current harmonics introduced in the alternating current network of static converter-asynchronous motor drive systems, which is necessary to establish the deformation factor. The values of the deforming regime are essential to obtain the harmonic compensation solutions. Originality. The originality of the paper consists in the approach to the measurements performed and the analysis of the deforming regime introduced by the electric drive systems. Practical implications. The values of the current and voltage harmonics were determined both by the laboratory measurements and by measurements made on the supply line of a bucket wheel excavator in different operating regimes.Мета. Дослідження та аналіз гармоніки струму й напруги, що з’являються в мережі змінного струму, а також деформуючого режиму, заданого системами приводу багатоковшового екскаватора на технологічній лінії кар’єра. Методика. Виконано лабораторні вимірювання для дослідження змінного деформуючого режиму, створюваного приводними системами зі статичним перетворювачем частоти – асинхронним двигуном. Виміри проводилися на лабораторному стенді з наступним обладнанням: асинхронний двигун (Pn = 3 кВт), непрямий статичний перетворювач частоти VARISPEED F7, генератор постійного струму, що працює як тормоз навантаження на приводний двигун, обладнання для аналізу якості енергії. Вимірювання проводились при запуску, зміні частоти та при різних значеннях напруги й навантаження, включаючи роботу без навантаження. Результати. Встановлено, що на виході інвертора деформуючий режим сильніше в разі напруги, ніж в разі електричного струму, що відбувається внаслідок особливого режиму формування кривих напруги на виході інвертора. Визначено, що на модернізованій виробничої лінії, що складається з оснащених випрямлячами з широтною модуляцією, спостерігалося, що гармонійний режим значно знижений у порівнянні з технологічними лініями, що не модернізуються і які використовують напівкеровані випрямлячі, тим самим, що вводять у режим гармоніки досить яскраво виражений гармонійний режим. Виявлено, що в разі модернізованих виробничих ліній немає суттєвих перешкод у зміні напруги й струму, але виявлено, що зміна коефіцієнта потужності є неадекватною, становить 0.5 і менше при більш високих значеннях навантаження, що пов’язано з більш довгими електричними лініями або впливом інших користувачів. Наукова новизна. Розроблено принципово новий підхід до експериментальних вимірів якості електроенергії та аналізу деформуючого режиму, викликаного системами електроприводу. Практична значимість. Отримані результати дозволяють модернізувати якість системи електропостачання та підвищити якість електроенергії для виїмкової техніки при відкритій розробці родовищ.Цель. Исследование и анализ гармоники тока и напряжения, появляющихся в сети переменного тока, а также деформирующего режима, заданного системами привода многоковшового экскаватора на технологической линии карьера. Методика. Выполнены лабораторные измерения для исследования искажающего деформирующего режима, создаваемого приводными системами со статическим преобразователем частоты – асинхронным двигателем. Измерения проводились на лабораторном стенде со следующим оборудованием: асинхронный двигатель (Pn = 3 кВт), непрямой статический преобразователь частоты VARISPEED F7, генератор постоянного тока, работающий как тормоз нагрузки на приводной двигатель, оборудование для анализа качества энергии. Измерения проводились при запуске, изменении частоты и при различных значениях напряжения и нагрузки, включая работу без нагрузки. Результаты. Установлено, что на выходе инвертора деформирующий режим сильнее в случае напряжения, чем в случае электрического тока, что происходит вследствие особого режима формирования кривых напряжения на выходе инвертора. Определено, что на модернизированной производственной линии, состоящей из оснащенных выпрямителей с широтной модуляцией, наблюдалось, что гармонический режим значительно снижен по сравнению с технологическими линиями, которые не модернизируются и которые используют полууправляемые выпрямители, тем самым вводящие в режим гармоники достаточно ярко выраженный гармонический режим. Выявлено, что в случае модернизированных производственных линий нет сильных помех в изменении напряжения и тока, но обнаружено, что изменение коэффициента мощности неадекватно, составляет 0.5 и менее при более высоких значениях нагрузки, что связано с более длинными электрическими линиями или влиянием других пользователей. Научная новизна. Разработан принципиально новый подход к экспериментальным измерениям качества электроэнергии и анализа деформирующего режима, вызванного системами электропривода. Практическая значимость. Полученные результаты позволяют модернизировать системы электроснабжения и повысить качество электроэнергии для выемочной техники при открытой разработке месторождений.The authors state that this research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors

Impact of Sodium–Glucose Cotransporter 2 (SGLT2) Inhibitors on Arterial Stiffness and Vascular Aging—What Do We Know So Far? (A Narrative Review)

Vascular aging, early vascular aging or supernormal vascular aging are concepts used for estimating the cardiovascular risk at a certain age. From the famous line of Thomas Sydenham that “a man is as old as his arteries” to the present day, clinical studies in the field of molecular biology of the vasculature have demonstrated the active role of vascular endothelium in the onset of cardiovascular diseases. Arterial stiffness is an important cardiovascular risk factor associated with the occurrence of cardiovascular events and a high risk of morbidity and mortality, especially in the presence of diabetes. Sodium–glucose cotransporter 2 inhibitors decrease arterial stiffness and vascular resistance by decreasing endothelial cell activation, stimulating direct vasorelaxation and ameliorating endothelial dysfunction or expression of pro-atherogenic cells and molecules

Disciple-COA: From Agent Programming to Agent Teaching

This paper presents Disciple-COA, the most recent learning agent shell developed in the Disciple framework that aims at changing the way an intelligent agent is built: from “being programmed ” by a knowledge engineer, to “being taught ” by a domain expert. Disciple-COA can collaborate with the expert to develop its knowledge base consisting of a frame-based ontology that defines the terms from the application domain, and a set of plausible version space rules expressed with these terms. Its central component is a plausible reasoner that can distinguish between four types of problem solving situations: routine, innovative, inventive and creative. This ability guides the interactions with the expert during which the agent learns general rules from specific examples, by integrating a wide range of knowledge acquisition and machine learning strategies, including apprenticeship learning, empirical inductive learning from examples and explanations, and analogical learning. Disciple-COA was developed in the DARPA's High Performance Knowledge Bases program to solve the challenge problem of critiquing military courses of action that were developed as hasty candidate plans for ground combat operations. We present the course of action challenge problem, the process of teaching Disciple-COA to solve it, and the results of DARPA’s evaluation in which Disciple-COA demonstrated the best knowledge acquisition rate and problem solving performance. We also present a separate knowledge acquisition experiment conducted at the Battle Command Battle Lab where experts with no prior knowledge engineering experience succeeded to rapidly teach Disciple-COA to correctly critique courses of action

Highlighting the Benefits of Rehabilitation Treatments in Hip Osteoarthritis

Background and objectives: Due to its frequency and possible complications, hip arthrosis or hip osteoarthritis (hip OA) has a high social impact, its advanced stages eventually leading to irreversible lesions involving major complications or surgery. In the early stages, conservative treatment plays a key role in the prophylaxis of complications and in slowing down the degenerative process. The association between an appropriate drug therapy (DT) and a rehabilitation treatment (RT)—including individualized physical therapy (PT) and adapted occupational therapy (OT)—provides good results. Our objective was to highlight the benefits of associating RT with DT in patients with hip OA. Materials and Methods: An observational follow-up study was conducted between 2018–2021, which included 100 patients with hip OA divided into two groups: the study group—group A (50 subjects who complied with RT) and the control group—group B (who did not comply with RT). To evaluate them, the evolution of the Lequesne hip index (LHI), Tinetti test (TT) and the hip joint mobility: flexion (FH) and abduction (AH) were monitored before the beginning of the study (T0) and after one-year (T1) for each patient. The mean values of the parameters, the standard deviations, the frequency intervals, as well as the tests of statistical significance were calculated using the Student method (t-test) and χ2, ANOVA (Bonferroni) being used to compare the means. Results: Compared to the evolution of group B, improvements were observed in group A, as follows: in LHI group A (p = 0.023) vs. group B (p = 0.650); in TT group A (p = 0.011) vs. group B (p p = 0.001) vs. group B (p = 0.025); in AH group A (p = 0.001) vs. group B (p p = 0.223) and B (p = 0.513). Evaluating group A, the most significant improvements of the studied parameters were observed in the age group 41–50 years. Conclusions: The study reveals the benefits of combining RT with DT in patients with especially early-stage hip OA, aged up to 50 years old

Highlighting the Benefits of Rehabilitation Treatments in Hip Osteoarthritis

Background and objectives: Due to its frequency and possible complications, hip arthrosis or hip osteoarthritis (hip OA) has a high social impact, its advanced stages eventually leading to irreversible lesions involving major complications or surgery. In the early stages, conservative treatment plays a key role in the prophylaxis of complications and in slowing down the degenerative process. The association between an appropriate drug therapy (DT) and a rehabilitation treatment (RT)—including individualized physical therapy (PT) and adapted occupational therapy (OT)—provides good results. Our objective was to highlight the benefits of associating RT with DT in patients with hip OA. Materials and Methods: An observational follow-up study was conducted between 2018–2021, which included 100 patients with hip OA divided into two groups: the study group—group A (50 subjects who complied with RT) and the control group—group B (who did not comply with RT). To evaluate them, the evolution of the Lequesne hip index (LHI), Tinetti test (TT) and the hip joint mobility: flexion (FH) and abduction (AH) were monitored before the beginning of the study (T0) and after one-year (T1) for each patient. The mean values of the parameters, the standard deviations, the frequency intervals, as well as the tests of statistical significance were calculated using the Student method (t-test) and χ2, ANOVA (Bonferroni) being used to compare the means. Results: Compared to the evolution of group B, improvements were observed in group A, as follows: in LHI group A (p = 0.023) vs. group B (p = 0.650); in TT group A (p = 0.011) vs. group B (p < 0.001); in FH group A (p = 0.001) vs. group B (p = 0.025); in AH group A (p = 0.001) vs. group B (p < 0.001). BMI changes were non-significant in both groups A (p = 0.223) and B (p = 0.513). Evaluating group A, the most significant improvements of the studied parameters were observed in the age group 41–50 years. Conclusions: The study reveals the benefits of combining RT with DT in patients with especially early-stage hip OA, aged up to 50 years old

Benefits of Combining Physical Therapy with Occupational Therapy in Hip Arthroplasty

(1) Background: Hip arthroplasty (HA) is a surgery that replaces the damaged hip joint with an artificial implant called a hip prosthesis. The increase in life expectancy correlated with the population aging level, to which the increase in the number of prosthetic interventions among the young population is added, translates to the imperative need to analyze the quality of life beyond the immediate postoperative period. Strict adherence to an individualized rehabilitation program (IRP), and adapted to each patient, is followed by an improved quality of life. The main goal is the recovery of the patient with HA. This study was aimed to demonstrate that an IRP, represented by physical therapy associated with occupational therapy, improves the quality of life of patients with HA; (2) Methods: In this study, conducted between 2019 and 2021, 50 patients with HA were divided into two groups: study group—group A (25 subjects compliant with the IRP) and control group—group B (25 subjects, non-compliance with the IRP). To evaluate the two study groups, we monitored the evolution of the modified Harris hip score (mHHS) in both hips (arthroplasty hip (AH), contra lateral hip (CH)), for four months, respectively 30 days before the surgery (T0) and at 90 days after the surgery (T1); (3) Results: We notice significant differences in mHHS values at 90 days-T1 after surgery, both on AH in favor of subjects from group A vs. group B (p = 0.030) and on CH, where mHHS values were statistically higher in group A compared to group B (p < 0.001). The results of our study outline at T1 moment, both on the AH (p = 0.030) and on the CH (p < 0.001), the fact that mHHS values were statistically higher in patients included in group A compared to group B. In terms of the results for mHHS, comparing AH with CH, it is noted that the number of subjects who had a good or excellent mHHS result in group A versus group B is statistically significant in the case of CH (group A: 23 (92%) vs. group B: 11 (44%), p = 0.039); (4) Conclusions: The study reveals clear advantages of HA in both hips, both in subjects who complied with the IRP and those who did not comply; the higher therapeutic benefits of IRP are outlined at the level of CH compared to AH; in patients who comply with the IRP, the mHHS parameters that have improved in both CH and AH are pain, leaning, and shoes and socks activities; in addition, limping was reduced in CH

Cardiovascular Involvement in Tuberculosis: From Pathophysiology to Diagnosis and Complications—A Narrative Review

Although primarily a lung disease, extra-pulmonary tuberculosis (TB) can affect any organ or system. Of these, cardiovascular complications associated with disease or drug toxicity significantly worsen the prognosis. Approximately 60% of patients with TB have a cardiovascular disease, the most common associated pathological entities being pericarditis, myocarditis, and coronary artery disease. We searched the electronic databases PubMed, MEDLINE, and EMBASE for studies that evaluated the impact of TB on the cardiovascular system, from pathophysiological mechanisms to clinical and paraclinical diagnosis of cardiovascular involvement as well as the management of cardiotoxicity associated with antituberculosis medication. The occurrence of pericarditis in all its forms and the possibility of developing constrictive pericarditis, the association of concomitant myocarditis with severe systolic dysfunction and complication with acute heart failure phenomena, and the long-term development of aortic aneurysms with risk of complications, as well as drug-induced toxicity, pose complex additional problems in the management of patients with TB. In the era of multidisciplinarity and polymedication, evidence-based medicine provides various tools that facilitate an integrative management that allows early diagnosis and treatment of cardiac pathologies associated with TB