Search

The methodology for the evaluation of long-term exposure to the overhead line magnetic field is presented, in this paper. The developed methodology is based on the ambient temperature measurements and phase conductors' height measurements to find a linear regression model to determine phase conductors' height changes for different ambient temperatures. Based on the overhead transmission line geometry, and datasets about historical overhead line phase current intensity values and ambient temperatures long-term magnetic field exposure can be determined. For magnetic flux density determination, a method based on artificial neural networks is used. The methodology is applied to the case study of overhead line that connect substations Sarajevo 10 and Sarajevo 20. A period of one year is analyzed and magnetic flux density values are determined. The obtained results indicate that during the analyzed period for significant amounts of time magnetic flux density values surpass the recommended values for long-term exposure. [ABSTRACT FROM AUTHOR]

This paper deals with an advanced electromagnetic radiation approach for analyzing the time-domain performance of grounding systems under pulse excitation currents. The model of the grounding systems presented within this paper is based on the homogeneous Pocklington integro-differential equation for the calculation of the current distribution on the grounding system and Lorentz gauge condition which is used for the grounding system transient voltage calculation. For the solution of the Pocklington integro-differential equation, the indirect boundary element method and marching on-in time method are used. Fur- thermore, the solution technique for the calculation of the grounding system transient voltage is presented. The numerical model for the calculation of the grounding system transients was verified by comparing it with onsite measurement results.

The decrease in overall inertia in power systems due to the shift from synchronous generator production to renewable energy sources (RESs) presents a significant challenge. This transition affects the system's stable frequency response, making it highly sensitive to imbalances between production and consumption, particularly during large disturbances. To address this issue, this paper introduces a novel approach using Multivariate Empirical Mode Decomposition (MEMD) for the accurate estimation of power system inertia. This approach involves applying MEMD, a complex signal processing technique, to power system frequency signals. The study utilizes PMU (Phasor Measurement Unit) data and simulated disturbances in the IEEE 39 bus test system to conduct this analysis. MEMD offers substantial advantages in analyzing multivariate data and frequency signals during disturbances, providing accurate estimations of system inertia. This approach enhances the understanding of power system dynamics in the context of renewable energy integration. However, the complexity of this methodology and the requirement for precise data collection are challenges that need to be addressed. The results from this approach show high accuracy in estimating the rate of change of frequency (RoCoF) and system inertia, with minimal deviation from actual values. The findings highlight the significant impact of renewable energy integration on system inertia and emphasize the necessity of accurate inertia estimation in modern power systems. [ABSTRACT FROM AUTHOR]

Introduction: Previous studies have found that, in addition to the general factors for the occurrence of pain and reduced mobility of the cervical spine, the use of electronic devices promotes these, the excessive use of which can also lead to the occurrence of depressive symptoms in students. The aim of this study was to determine the mobility limitation of the cervical spine in students with reported neck pain, to determine the degree of disability and depression due to neck pain, to determine the correlation of mobility limitation of the cervical spine with the degree of disability and depression of students, and to determine the correlation of the degree of disability with the degree of depression. Methods: The research was conducted as a cross-sectional study from May to July 2021 at the University of Zenica in four faculties. The study used the General Questionnaire and two standardized questionnaires to assess disability due to neck pain (Index of Disability due to Neck Pain) and the degree of depression (patient health questionnaire). Results: A total of 147 students with reported neck pain participated in the study. A limitation of mobility was found in 30.6% of the students in flexion, 25.2% in rotation, 23.8% in lateral flexion, and 20.4% on extension. Mild disability due to neck pain was found in 58.5% of students, moderate in 23.8%, and severe in 2.7%. 45.6% of the students had mild depression, 18.4% had moderate depression, and 5.4% had severe depression. Conclusion: Restricted flexion and rotation are more common than restricted lateral flexion and extension of the cervical spine. About half of the students who reported neck pain had a mild degree of disability and mild depression. A strong positive correlation was found between the degree of disability and depression in students with neck pain. [ABSTRACT FROM AUTHOR]

In this article the summary of measurement and calculation values of low frequency electric field radiation around the high-voltage transmission lines and impact of the increased voltage values on the AC corona onset voltage gradient are presented. The measurements of the low frequency electric field radiation level were performed under the 400 kV transmission lines of horizontal configuration with standard and compact dimensions. In all cases analyzed in this article, the measurements are performed in the middle of the span, because at this point the conductors are closest to the ground. The analysis in this article has been initiated by the increased voltage values of long duration that have been registered in nodes of the 400 kV network in Bosnia and Herzegovina and the neighbouring countries during the last years. The calculation of the low frequency electric field radiation of the different configuration of the high-voltage transmission lines will be useful for determining the non-ionization radiation exposure levels of the general public in the future as well as to determine their impact on the AC corona onset voltage gradient.

The paper discusses the possibility of improving the character of gas surge arresters. Examined were: the magnetic field effect, the effect of the hollow cathode, and the effect of the alpha radiation source 241Am. Numerical and real experiments conducted are presented together with theoretical interpretations of the obtained results. Real experiments were carried out on a model of a gas surge arrester spatially constructed for experiments presented in this paper. The model was designed in such a way that it was possible to change all the relevant parameters of the gas surge arrester model. Experiments were conducted under well-controlled laboratory conditions. The tests were performed with d. c. and impulse voltage. The results obtained by experiments were processed by sophisticated statistical methods. The expressed measurement uncertainty of the experimental procedure showed a high statistical reliability of the obtained results. Based on the results of the research, the model of a gas surge arrester, in which the effect of the hollow cathode and the radioactive source 241Am were combined, unambiguously proved to have the best characteristics.

Introduction: As a result of research conducted globally, experts continue to extensively study the long-term consequences that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can have on patients, as well as the factors contributing to severe outcomes. The aim of this study was to investigate the values of basic biochemical and hematological parameters in patients with fatal outcomes of SARS-CoV-2 infection, as well as to determine the combination of hematological and biochemical parameters that contribute to the progression of SARS-CoV-2 infection. The examined parameters were correlated with the age and gender distribution of patients with fatal outcomes from the SARS-CoV-2 infection. Methods: The study represents a retrospective study of patients hospitalized at the Cantonal Hospital Zenica from February to April 2021, focusing on the biochemical and hematological parameters of subjects with confirmed presence of the SARS-CoV-2 virus using the reverse transcription-polymerase chain reaction methods who were hospitalized at the Cantonal Hospital Zenica. Results: Of the 250 deceased subjects in the sample, females comprised the relative majority at 53.6%. Among the examined parameters, hemoglobin, mean corpuscular hemoglobin (MCH), and MCH were significantly lower in females compared to males, while males had significantly higher values of urea, creatinine, and troponin. The average age of the patients was 74 years, and with aging, the values of erythrocytes, hemoglobin, and troponin increased. Troponin showed a statistically significant positive correlation with age, as well as with urea and creatinine. Conclusion: We can conclude that hemoglobin, urea, creatinine, and troponin are parameters that can be considered to contribute to the progression of SARS-CoV-2 infection. These parameters can be useful for assessing disease severity and prognosis in patients infected with the SARS-CoV-2 virus. [ABSTRACT FROM AUTHOR]

Introduction: Knee osteoarthritis (OA) develops gradually and causes pain, a decrease in range of motion, muscle mass, and strength and leads to a decrease in physical activity and a poor quality of life for the patient. The aim of this study was to investigate the effects of different physiotherapy programs on pain intensity, range of motion, and quality of life in people with knee OA. Methods: The study was designed as a prospective, experimental, and randomized trial. Sixty subjects of both sexes and all ages with OA of the knee were enrolled in the study. In the studied Group I (n = 30), in addition to the standard protocol, high induction electromagnetic stimulation was applied using a Salus Talent device with a strength of 3 T and a frequency of up to 50 Hz for 10 min. In the test Group II (n = 30), in addition to the standard protocol, high-intensity laser therapy (HILT) with a power of 5 J was applied with the help of the Ilux Yag 1064 device for 7 min. The therapy protocol for both test groups lasted 8 weeks, with subjects treated once a week. Results: Analysis of the mean scores on the VAS scale shows that in both groups, the lowest mean scores were recorded in the III measurement (4.35) and the highest in the I measurement (7.96). In all three measurements, there was a difference in the extent of mobility of internal rotation in the form of a higher average range of motion in the test group II, in which HILT was applied. Analysis of the mean scores on the knee injury and osteoarthritis outcome score quality of life scale showed that in both groups, the lowest mean scores were recorded at the first measurement (14.84), with the mean score increasing at the second (32.95) and third measurements (41.08). Conclusion: Both methods showed significant results in reducing pain intensity, improving knee mobility, activities of daily living, and quality of life in people with knee OA. The obtained data do not give preference to any method but indicate them as adequate physiotherapy protocols to improve the function and quality of life of people with knee OA. [ABSTRACT FROM AUTHOR]

Copyright of Electrotechnical Review / Elektrotehniski Vestnik is the property of Electrotechnical Society of Slovenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to decide the appropriate arrangements of fictitious charges in the charge simulation method, the use of the Monte Carlo method is proposed for the estimation of the probability density function of two variables, the radius ratio, and the angle ratio. The scale and shape parameters of the Weibull's distribution are determined by the maximum likelihood estimator. The obtained results are used to calculate the electric field at arbitrary points in the neighborhood of high voltage transmission lines. The comparisons between the results computed by this method, the results calculated by the genetic algorithm, and those measured, confirm the effectiveness and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Introduction: Neck pain (NP) may have a local mechanical (non-specific) origin caused by dysfunction of the joint, muscle, and ligament structures in the neck or by a discogenic etiology. Most people (50–60%) suffer from NP at some point in their lives. They are more common in highly developed countries and in urban areas. The aim of this study is to determine the prevalence of NP and its impact on daily living activities in the student population. Methods: The study included students of the University of Sarajevo - Faculty of Health Studies in the period from May 2021 to June 2021. The sample of respondents was formed by the method of random selection and included respondents of both sexes, aged 19–28 years. The study was conducted as a transversal cross-sectional study at a specific time point on the frequency of NP and the ability to perform activities of daily living in the student population. Results: Out of the total number of 255 respondents, 77 (30.2%) reported that they have NP while 178 (69.8%) respondents reported that they do not feel NP and it was found that there was no statistically significant difference between the age groups of the subjects with and without NP. The study concluded that a higher percentage of respondents with NP did not engage in leisure activities and that respondents with NP had lower mobility in daily life, sleep disturbance, and poorer ability to perform activities of daily living due to NP. Conclusion: The study conducted revealed that a significant percentage of the student population with NP has a lower ability to perform activities of daily living. Considering the above facts and the current transformation of the educational model, in which static postures dominate, it is necessary to design and implement programs for targeted physical activity and prevention of long-term inactivity that leads to painful musculoskeletal syndromes. [ABSTRACT FROM AUTHOR]

Copyright of B&H Electrical Engineering is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the detection method and analysis methodology of dynamic stray current effects on underground pipelines based on simultaneous multiparametric measurements in combination with continuous wavelet cross‐correlation and frequency plots. Measurements presented within this paper were conducted at two locations experiencing tram induced dynamic stray currents, in the first case, on unprotected pipeline and in the second case, on pipeline under cathodic protection. On both pipelines, measurements of pipe‐to‐soil potential, lateral potential gradient, corrosion probe current, and pipeline current were simultaneously done for time period of 20 min. For both locations, the two wavelet cross‐correlation spectrograms for the quantities: lateral potential gradient and probe current versus pipe‐to‐soil potential show that 5% statistical significance levels are in periods between 16 and 128 s. Time spans and period lengths of observed cross‐correlations on spectrograms reflect the stray current influence that may be linked to specific events, such as passing of trams. On the other hand, frequency plots of the measured quantities give clear visual representation of the time that pipeline spends in a certain state related to the possible harmful effect of stray current and also show the degree of cathodic protection beneficial effect. A novel analysis methodology of dynamic stray current impact on the underground pipelines is presented. The methodology was applied on two pipelines that are under influence of dynamic stray current, one being unprotected and second one being protected by cathodic protection system. The severity of stray current influence for each location has been deduced and the benefits of application of the cathodic protection system have been illustrated. [ABSTRACT FROM AUTHOR]