Body Impedance Research Articles

A high adherence level to nutritional recommendations minimizes protein and minerals loss while maximizes visceral fat loss in bariatric surgery patients

BackgroundMetabolic bariatric surgeries are considered the finest and most appropriate treatment option for patients with severe obesity. Besides the surgical procedure, many factors appear to be associated with improved postoperative outcomes such as compliance to the postoperative diet and supplementation, regular physical activity, medical and nutritional follow-up, and modifications in dietary habits. The objectives of this study were to investigate the effect of adherence to post-operative recommendations on anthropometric measurements and body composition and assess the percentage of total weight loss (%TWL) and excess weight loss (%EWL) 3 months post-operative. Material and MethodsFifty-two participants who underwent a Roux-en-Y gastric bypass or sleeve gastrectomy were included. Participants have filled out a pre-operative questionnaire. Anthropometric measurements were obtained pre-operative and 3 months post-operative using a Body Impedance Analyzer (Inbody 270). The adherence to post-operative recommendations was assessed by the Bariatric Surgery Self-management Questionnaire 3 months post-operative and classified to three adherence levels. ResultsMost anthropometric measurements decreased 3 months post-operative in the three adherence groups (p≤0.05). No significant differences were observed between groups in anthropometric measurements and body composition, except for minerals and visceral fat levels. The mineral loss has decreased in both the high and intermediate adherence groups (-0.09 ± 0.22 kg, and -0.09 ± 0.18 kg, respectively). Also, the high adherence group showed less loss in protein amount post-operatively (p=0.06). Visceral fat level decreased in the high adherence group (p≤ 0.05). ConclusionAdherence to post-operative behavioral and nutritional recommendations was associated with less protein and mineral loss and enhanced visceral fat reduction post-operatively.

Enhancing Electric Field Distribution in the Pancreas for Improved TTFields Therapy: A Computational Modeling Investigation.

Tumor treating fields (TTFields) therapy has shown effectiveness in glioblastoma treatment and holds potential for other cancers. However, its application in pancreatic cancer and the distribution of electric fields in pancreas remain unexplored. This study aims to investigate the electric field distributions in pancreatic regions using different array configurations for TTFields therapy. Computational modelling was employed to simulate electric field distributions, and quantitative analysis was conducted. Human body impedance measurements were used to optimize the electric properties of the model. Various array configurations were examined to assess their impact on the electric field distributions. The study revealed that well-positioned arrays, specifically the combination of 20-piece transducer arrays in anterior-posterior orientation and 13-piece transducer arrays in left-right orientation, consistently achieved electric fields exceeding the 1V/cm threshold in over 99.4% of the pancreas. Even with a reduced number of transducers (13 pieces for both orientations), sufficient electric field coverage was achieved, exceeding the threshold in over 92.9% of the pancreas. Additionally, different array placements within the same orientation were explored to address clinical challenges such as skin rash and patient anatomical variations. This research lays the groundwork for understanding TTFields distribution within the abdomen, offering insights into optimizing array configurations for improved electric field delivery. The findings have the potential to guide practical designs of TTFields devices, enhance treatment efficacy, and improve patient outcomes. These results offer promises of advancing TTFields therapy for pancreatic cancer towards clinical applications, and potentially enhancing treatment efficacy and patient outcomes.

Abstract 40: Sodium-mediated Blood Pressure Increase in Chronic Kidney Disease and Diabetic Kidney Disease Patients Coincides With Vasodysfunction.

Background: Chronic kidney disease (CKD) and diabetic kidney disease (DKD) patients are advised to limit salt intake, because of its detrimental effects on blood pressure (BP) and albuminuria. The salt-sensitive BP response in these patients may be attributed to impaired renal ability to excrete sodium (Na+) resulting in fluid overload and/or vasodysfunction. To define which factor relates to BP sensitivity in both CKD and DKD, we studied the Na+-mediated BP response in these patients as compared to healthy volunteers (HV). Methods: In this randomized crossover study, CKD patients (KDIGO stage G2/3A, proteinuria >0.5 g/d), Type 2 DKD patients (KDIGO stage G2/3A, proteinuria 0.2 - 0.5 g/d) and HV followed a 7-day low sodium diet (LSD, <50mmol/d) and high sodium diet (HSD, >200mmol/d), respectively. After each diet, assessment of the hemodynamic profile included daytime BP (Mobil-O-Graph) and cardiac output (CO) measurements (using NexfinTM), by which SVR was calculated accordingly. Extracellular fluid volume (ECV) change was assessed with multi-frequency body impedance spectroscopy (Fresenius). Results: We included 20 CKD (mean age 48 yrs, median (IQR) proteinuria 0.7 (0.6-1.6) g/d, mean (SD) eGFR 60.7 (16.3) ml/min/1.73m2) and 8 DKD patients (age 68 yrs, proteinuria 0.3 (0.2-0.4) g/d, eGFR 59.0 (15.9) ml/min/1.73m2), and 16 HV (age 41 yrs). Dietary salt intervention was successful with mean difference in urine Na+ excretion of 185, 168, and 209 mmol/day in CKD, DKD and HV respectively. After HSD, mean (SD) systolic BP change was 9.3 mmHg (8.9; p<0.001) in CKD and 13.8 mmHg (10.4; p<0.01) in DKD, while systolic BP change (3.1 mmHg (6)) in HV was not significant. After HSD, we observed significant ECV expansion in all groups without differences between groups (CKD 1.6 L, DKD 1.6 L, HV 1.4 L, p=0.27), while no effects on CO were observed. After HSD, the mean (SD) SVR in CKD increased with 125.7 dyn*sec*cm-5 (247.9, p=0.04) and in DKD with 125.5 dyn*sec*cm-5 (142.6, p=0.04), while in HC a non-significant decline of -109.2 dyn*sec*cm-5 was observed (358.2, p=0.24). Conclusion: The Na+-mediated BP rise in both CKD and DKD coincides with an increase in SVR. The absence of differences in ECV and CO between the three groups indicates that salt sensitivity in both CKD and DKD is not completely based on fluid overload but might be due to an inability to induce vasodilation.

IEat: automatic wearable dietary monitoring with bio-impedance sensing

Diet is an inseparable part of good health, from maintaining a healthy lifestyle for the general population to supporting the treatment of patients suffering from specific diseases. Therefore it is of great significance to be able to monitor people’s dietary activity in their daily life remotely. While the traditional practices of self-reporting and retrospective analysis are often unreliable and prone to errors; sensor-based remote diet monitoring is therefore an appealing approach. In this work, we explore an atypical use of bio-impedance by leveraging its unique temporal signal patterns, which are caused by the dynamic close-loop circuit variation between a pair of electrodes due to the body-food interactions during dining activities. Specifically, we introduce iEat, a wearable impedance-sensing device for automatic dietary activity monitoring without the need for external instrumented devices such as smart utensils. By deploying a single impedance sensing channel with one electrode on each wrist, iEat can recognize food intake activities (e.g., cutting, putting food in the mouth with or without utensils, drinking, etc.) and food types from a defined category. The principle is that, at idle, iEat measures only the normal body impedance between the wrist-worn electrodes; while the subject is doing the food-intake activities, new paralleled circuits will be formed through the hand, mouth, utensils, and food, leading to consequential impedance variation. To quantitatively evaluate iEat in real-life settings, a food intake experiment was conducted in an everyday table-dining environment, including 40 meals performed by ten volunteers. With a lightweight, user-independent neural network model, iEat could detect four food intake-related activities with a macro F1 score of 86.4% and classify seven types of foods with a macro F1 score of 64.2%.

Ultrasound‐Driven Highly Stable Implantable Triboelectric Nanogenerator with Human‐Tissue Acoustic Impedance‐Matched Polyether Ether Ketone

AbstractImplantable electrical neurostimulators offer a promising avenue for treating neurological disorders. However, their dependency on a finite battery life limits their long‐term utility. Emerging transcutaneous ultrasound‐driven triboelectric nanogenerator (TENG) techniques provide solutions for converting external ultrasound waves into internal electricity. This study proposes an implantable ultrasound‐driven TENG (IU‐TENG) using polyether ether ketone (PEEK) for its exceptional stability inside a human body and acoustic impedance compatibility with human tissues. This IU‐TENG remarkably surpasses traditional titanium‐based encapsulation, resulting in a 99.94% efficiency in ultrasound transmission. In addition, PEEK contains numerous electron‐donating functional groups, making it suitable for TENG applications, particularly as a positive triboelectric layer. The device exhibits robust voltage outputs, reaching up to 11.50 and 8.75 V in water and in vivo, respectively, under body‐safe ultrasound intensities. Moreover, its ability to sustain a stable electrical output for over 300 min emphasizes the durability and mechanical resilience of PEEK. In vivo mouse models and ex vivo porcine tissue trials demonstrate the effectiveness of the IU‐TENG in nerve stimulation, showing its potential in medical treatments, enhancing the functionality and longevity of implantable medical devices.

Ten-electrode bioelectrical impedance analysis (BIA) system: Sensitivity investigation by simulation and phantom experiment

Sensitivity of Bioelectrical Impedance Analysis (BIA) measurement was investigated in this study. Limb segments and the trunk of the body are usually assessed for the whole body impedance in the common-used eight-electrode system. However, even though the trunk is the largest part, the measurement sensitivity of the trunk part is extremely low resulting in low trunk impedance. In this study, a ten-electrode BIA system is proposed to improve the sensitivity of the trunk region by adding two more electrodes at the abdomen and proposing a new measurement scheme. Simulation results showed that the proposed system improved the sensitivity in the trunk region by 3.4–4.2 times. With the eight-electrode system, the content of a body segment could also affect the measured impedance of the other segments, but this effect was substantially reduced in the proposed system. The simulation results were confirmed by a phantom experiment on a piece of pork.

Study protocol for a non-inferiority, multicenter, randomized study to evaluate a smartphone app-based follow-up program after bariatric surgery (BELLA plus trial)

IntroductionAdherence to follow-up (FU) care after bariatric surgery is poor despite strong recommendations. In our pilot Bella trial, we demonstrated that a completely remote follow-up program via smartphone is feasible and safe for patients after bariatric surgery. Building on this, we aim to verify our results in a multicenter, randomized controlled setting. MethodsThis trial plans to enroll 410 participants undergoing primary bariatric surgery in seven German bariatric centers. Participants are randomized into two groups: a control group receiving in-person FU according to the standard in the bariatric centers, and an interventional group monitored using a smartphone application (app). The app sends standardized questionnaires and reminders regarding regular vitamin intake and exercises. The built-in messaging function enables patients to communicate remotely with medical care professionals. After one year, all participants are evaluated at their primary bariatric centers. The primary outcome is weight loss 12 months after surgery. The secondary outcomes include obesity-related comorbidities, quality of life, serum values of vitamins and minerals, body impedance analysis, visits to the emergency department or readmission, patient compliance, and medical staff workload. DiscussionThe current study is the first prospective, individually randomized-controlled, multicenter trial where a mobile application completely replaces traditional in-person visits for post-bariatric surgery follow-ups in bariatric centers.

Wearable-Based Integrated System for In-Home Monitoring and Analysis of Nocturnal Enuresis.

Nocturnal enuresis (NE) is involuntary bedwetting during sleep, typically appearing in young children. Despite the potential benefits of the long-term home monitoring of NE patients for research and treatment enhancement, this area remains underexplored. To address this, we propose NEcare, an in-home monitoring system that utilizes wearable devices and machine learning techniques. NEcare collects sensor data from an electrocardiogram, body impedance (BI), a three-axis accelerometer, and a three-axis gyroscope to examine bladder volume (BV), heart rate (HR), and periodic limb movements in sleep (PLMS). Additionally, it analyzes the collected NE patient data and supports NE moment estimation using heuristic rules and deep learning techniques. To demonstrate the feasibility of in-home monitoring for NE patients using our wearable system, we used our datasets from 30 in-hospital patients and 4 in-home patients. The results show that NEcare captures expected trends associated with NE occurrences, including BV increase, HR increase, and PLMS appearance. In addition, we studied the machine learning-based NE moment estimation, which could help relieve the burdens of NE patients and their families. Finally, we address the limitations and outline future research directions for the development of wearable systems for NE patients.

Evaluation of adults' acumen exerted from cerebral stress with quantified anthropometric indices using bioelectrical impedance analysis

This work considers cerebral stress-struck adults to assess their ‘acumen’ with four quantified anthropometric indices like cell membrane capacitance (CM), total body impedance (TBI), total body fat (TBF), and total body water (TBW). Primarily, a bio-impedance model of the epithelial tissue structure of human body has been presented and anatomized considering mental stress driven hormonal changes happen inside human body to propose several preambles. Secondly, an intelligence quotient (IQ) test designed to create ‘racing’ thoughts has been conducted right before measuring indices using bioelectrical impedance spectroscopy (BIS) method. Finally, juxtaposed investigations to vindicate the correlation between bio-impedance model-implied preambles and the variance of the four quantified indices were made by comparing them to the IQ test outcomes. This article reports, an effectively innervated nervous system having homeostasis endocrine human anatomy with CM, TBI, TBF, and TBW, in the range of 1.0–2.1 nF, 470–550 Ω, 7.9–20%, and 56.8–80%, respectively for the subjects whose acumen is classified as “Class-A", while “Class-B" subjects are also presented with other distinct quantified indices. The outcomes of this work are expected to be a paradigm in the digital judgment of adults' psychological engagement to any tasks.

Assessing the Body Composition of "Picky Eaters" Using Body Impedance Analysis: An Experience From a Tertiary Care Center.

Picky eating might be associated with a higher risk of being underweight and poor growth. This study aimed to investigate if picky eaters aged between three and 12 yearsshowed differences in height, weight, and body composition compared to their non-picky peers using a body impedance analysis (BIA). This cross-sectional study was conducted between March 1, 2022, and July 31, 2022, on children aged three to 12 years who presented to the outpatient pediatric clinics at Al Habib Ar Rayyan in Riyadh, Saudi Arabia. Body composition was measured using BIA after manually inserting the height, gender, and age into the machine, where body mass index (BMI), fat mass, and skeletal muscle mass were recorded. Participants were classified as under/normal/over for each body composition measurement. A total of 2234 children were entered into the final data analysis. Our analysis showed that 1917 (85.8%) were Saudis and 1117 (50%) were males. The mean age of participants was 6.08±2.01 years and 1151 (51.5%) were in the pre-school age. The reported prevalence of picky eaters was 1684 (75.4%), of whom, 606 (27.0%) were selective eaters, 365 (16.2%) were low appetite eaters, and 723 (32.2%) were both selective and low appetite eaters. Being underweight was significantly more common among the picky eaters 487 (28.9%) compared to those non-picky eaters 55 (10.0%) (p<0.001). Significantly, 1280 (76%) picky eaters had below-average skeletal muscle mass compared to 151non-picky eaters (27.5%) (p<0.001). The low appetite picky eater group had more under skeletal muscle mass children 277 (75.9%) compared to the selective picky eater group412 (68.0%) (p=0.009).Additionally, the low appetite group possessed lower muscle ratios (p=0.012) and were more underweight than the selective group (p<0.001). Furthermore, the low appetite group showed a higher percentage of children below the 3rd percentile in the height for age category (p=0.003) compared to the selective group. This study is the first of its kind in Saudi and globallyto evaluate body composition using BIA among children. The study showed that picky eating is more associated with underweight children and low muscular mass. Despite the normal BMI, height, and weightof a picky eater, their skeletal muscle mass might be less than average,which could be associated with an increased risk of morbidity.

Implementation of Bioelectrical Impedance Measuring Instrument Based on Embedded System

The present research aims to measure the segmental bioelectrical impedance (BI) of the human body at multifrequency, using a server user interface-based prototype, which provides subjects with measured data online anywhere accessed by their unique identifications. The present research measures the BI of the human leg and arm at a multifrequency range of 50–400 kHz with a developed and standard device. Recorded data can be transferred to the subject using Wi-Fi technology with their unique identifications and password. The system uses Wi-Fi interfacing for real-time data measurement and online data storage. The prototype can be used commercially. The compact size of the prototype becomes the demand of the common population. The pocket carry size makes it easy to carry anywhere for regular monitoring of the human body to prevent critical disease. The resultant data show that the mean and standard deviation of the left and right leg are 282.2 ± 14.29 and 274.80 ± 13.91 Ω, respectively. Similarly, in the case of the left arm and right arm, the mean and standard deviation are 325.41 ± 16.54 and 320.73 ± 16.07 Ω, respectively. The relative error between developed and standard devices is 3.53%. Results show that the left leg and arm impedance is always greater. However, the right leg and arm muscles are stronger than the left one, with less impedance at all frequencies.

Multipoint ECG Signal Extraction on Palms and Figures for Human Identification System

The ECG signal contain vital information for cardiac disease which is one of main cause of catastrophic mortality. In conventional technique, the signals are extracted through different points located on the limbs and surface of the chest. The biological impedance of human body eliminates any practical means of making fake copies of the relevant physiological traits. Moreover, this method needs the complex data acquisition system and apparatus as well as inconvenience way of acquisition of signal at the chest. Hence, there is a demand to find out the promising alternative technique to extract the ECG signals in more convenient way with high accuracy. In this paper, the real-time ECG monitor has been developed to extract the signals from the multipoint on the hands and fingers. Placement of the electrodes are done based on the acupressure point on palms and fingers. A total of 120 volunteers were investigated to develop the ECG database as the development dataset. This work uses the template matching algorithm and distance classification method to analyze and to find the best similarities between the developed dataset of ECG biometric signals to improve the identification rate. In order to lessen the noise that was recorded with the ECG signals, signal averaging was used to create ECG databases and templates. The recognition rate rose to 98% accuracy on the development dataset when the prescreening procedure was introduced to create a combined system model. ECG biometric model was created by combining the two models and using the development dataset's results. The algorithm was applied on the entire developed ECG dataset and 96% of accuracy rate was achieved in identification.

Effects of temperature on electrical impedance of biological tissues: ex-vivo measurements.

Bioelectrical impedance techniques have been useful in various applications, including body composition analysis, impedance plethysmography, impedance cardiography, lung ventilation, perfusion, and tissue characterization. Electrical impedance methods have also been useful in characterizing different foods like meat, fruits, and beverages. However, the temperature of tissue samples can change their dielectric properties, affecting their impedance. This research investigated the effects of temperature on the impedance of various biological tissues over the frequency range of 10 Hz to 5 MHz. Freshly excised animal tissues (lamb, cow, chicken), fish, fruits, and plants were considered as biological samples. The samples were placed in a test cell and submerged in a water bath heated by a hot plate to vary the temperature. Impedance measurements were conducted using a bioimpedance spectrometer in 2 °C steps within the temperature range of 20 °C to 50 °C. Impedance values decreased with increased temperature across all measurement frequencies for all biological samples. Curve fitting indicated that impedance decreased linearly with temperature, with a mean correlation coefficient of 0.972 for all samples. For all biological samples under investigation, the relative impedance change ranged from -0.58% to -2.27% per °C, with a mean and standard deviation of (-1.42±0.34) %/°C. On average, animal samples exhibited a higher relative temperature coefficient of -1.56% per °C (±0.41) across the frequency range, compared to -1.31% per °C (±0.26) for fruit and vegetable samples. Additionally, the relative temperature coefficient values were generally higher at lower frequencies than at higher frequencies. The findings of this research can be valuable for studies or biomedical applications involving variable tissue temperatures.

Ab. No. 118 Test-Retest Reliability of Commercially Available Bio-Electrical Impedance-Based Body Composition Analyzer in India

Introduction: The purpose of the study is to determine the consistency of body composition measures using a commercially available bioelectrical impedance-based body composition analyzer in India. Body composition assessment has application in several clinical populations including but not limited to those with obesity, cancer, renal failure, endocrine disorders. DEXA is considered gold standard but impractical to use in regular clinical practice. Bioelectrical impedance analysis (BIA) is emerging as a simpler alternative, especially in field settings and routine clinical practice. Its use is also recommended in current sarcopenia diagnostic guidelines. Many low-cost BIA devices are available but their reliability and validity information are seldom available. Such information can improve their relevance and utility in clinical settings. Methods: Forty apparently healthy adults (Age: 28±7.5 years; 78% women, BMI: 26.1±4.4). Following necessary approvals, body composition was assessed using four-point full body impedance analysis with Omron HBF-702T device on two occasions (1-4 days apart). The timing of measurement, food and fluid intake were not standardized to mimic clinical scenarios. Paired T-test determined significant difference between two assessments. Test-retest reliability was determined by ICC using two-way mixed methods model for consistency between measurements. Results: There was no clinically and statistically significant difference between two consecutive measurements (Mean difference of - Skeletal Muscle Percentage: 0.06%; Body Fat Percentage: 0.12%; RMR: 8.5 Kcal/day). All parameters exhibited excellent test-retest reliability (ICC &amp; Cronbach’s Alpha: Skeletal Muscle Percentage – 0.97 &amp; 0.98; Body Fat Percentage – 0.93 &amp; 0.96; RMR – 0.94 &amp; 0.97. Conclusion: The tested device exhibited excellent test-retest reliability for skeletal muscle, body fat percentage, and resting metabolic rate despite testing in non-standardized routine clinical setting. Implications: Bio-electrical impedance-based body composition analyzers could be a reliable way to measure body composition in clinical practice. However, each equipment’s reliability and validity needs to be established prior to clinical use.

Unraveling Age-Driven Shifts in Adolescent Cardiorespiratory Fitness: A Comprehensive Analysis Using the Yo-Yo Intermittent Endurance Test

Objective: This study aimed to examine cardiorespiratory responses during the Yo-Yo Intermittent Endurance Test in adolescents aged 14–18 years. Methods and Materials: A total of 80 male high school students participated, with 20 from each grade (9–12) at Pendik Vocational and Technical Anatolian High School in Istanbul. Anthropometric measurements, including height and weight, were recorded. Body composition was assessed using a Tanita body impedance analyzer, and aerobic capacity was evaluated using the Yo-Yo IR1 test. Statistical analyses, including ANOVA and Pearson correlation, were performed using SPSS v25. Findings: Significant differences were observed in height, distance covered, and VO2max across age groups. ANOVA revealed significant variations in height and distance covered, with older students performing better. Pearson correlation indicated strong positive relationships between Yo-Yo test levels, VO2max, and distance covered. Conclusion: The findings underscore the need for age-specific fitness assessments in physical education programs to optimize athletic performance during adolescence.

EFFECTS OF PHYSICAL EXERCISE ON ABILITY MEASURED BY FMS TESTS AND MENTAL HEALTH OF MIDDLE-AGED PERSONS

The aim of the research was to determine the impact of physical exercise on: 1. abi-lities measured by FMS tests, 2. the impact of physical status on the mental health of middle-aged people and 3. body composition. The research used a quasiexperimental design (test-retest). 20 respondents (11 men and 9 women) were included in this paper. The average age of the respondents is 52.3 years, average body height 169.4 cm, average body weight 78.62 kg. All respondents live in the territory of the United Arab Emirates, where they are physically minimally active or completely inactive. Body impedance (InBody120), FMS device and survey questionnaire were used in the research. Descriptive statistics and T-test were used for data processing. The results showed that there is a statistically significant difference in the variables that were measured at the beginning and after the application of the defined exercise program (test-retest), in the variable point score-FMS test (p = 0.000) and in the satisfaction questionnaire (p &lt; 0.05). However, the exercise program had no effect on body com-position because it focused on trunk mobility and stabilization exercises.

EFFECTS OF PHYSICAL EXERCISE ON ABILITY MEASURED BY FMS TESTS AND MENTAL HEALTH OF MIDDLE-AGED PERSONS

The aim of the research was to determine the impact of physical exercise on: 1. abi-lities measured by FMS tests, 2. the impact of physical status on the mental health of middle-aged people and 3. body composition. The research used a quasi-experimental design (test-retest). 20 respondents (11 men and 9 women) were included in this paper. The average age of the respondents is 52.3 years, average body height 169.4 cm, average body weight 78.62 kg. All respondents live in the territory of the United Arab Emirates, where they are physically minimally active or completely inactive. Body impedance (InBody120), FMS device and survey questionnaire were used in the research. Descriptive statistics and T-test were used for data processing. The results showed that there is a statistically significant difference in the variables that were measured at the beginning and after the application of the defined exercise program (test-retest), in the variable point scoreFMS test (p = 0.000) and in the satisfaction questionnaire (p &lt; 0.05). However, the exercise program had no effect on body com-position because it focused on trunk mobility and stabilization exercises.

Electromagnetic interference and the effect of low-voltage protective measures at electric vehicle charging stations

The nominal power of electric vehicle charging stations or charging parks is constantly increasing. Most of the users are ordinary persons and handle such equipment with a rated power of several 100 kW. Until now, equipment with such power ratings was only common in electrical operating facilities such as industrial plants where the users are at least instructed and protective measures are specified. If ordinary persons handle equipment with such power ratings in the field, the question arises as to whether the conventional safety goals are met in the event of an electrical fault. The consideration is: If the power increases so much, it can be assumed that the short-circuit power and thus the fault current increase and so does the risk of a dangerous electric shock. In this contribution, calculations of line-to-earth short-circuits on the low-voltage AC side of the three-phase system and their effects in typical configurations of charging stations are carried out. Considering the electromagnetic interference, the calculations provide the fault current and its distribution to determine the electrical potentials during the fault. From this, the (partial) fault voltages and active fault voltages are calculated. Based on the active fault voltage, the expected body impedance and consequently, the body current can be determined. With the body current and the break time of the protection device the risk of electric shock using international standards as guidelines is evaluated. As a result, recommendations for the planning, installation and safe operation of charging stations are given. It turns out that considering certain aspects like the conductor cross-sections or the electromagnetic interference, the risk of electric shock can be reduced to a conventional level. Periodic testing of the electrical system is necessary for safe and reliable operation. For example, follow-on faults due to unintended, improper use by ordinary persons can be prevented. Also, regular inspection of the electrical system is necessary for safe and reliable operation to prevent hazards due to aging or wear. However, it seems challenging to define an installation guideline that applies to all configurations as the boundary conditions vary depending on the type of system, installations in the area of interference and environmental influences.

Frequency‐Domain Dielectric Response of Insulating Paper with High Humidity

AbstractThe frequency‐domain dielectric spectroscopy (FDS) of humid insulating paper has been measured at different temperatures. The data show three independent dielectric processes: electrode polarization, hopping conductivity and interfacial polarization. The dielectric properties of humid insulating paper are composed of hopping conductivity and interfacial polarization, and its equivalent dielectric model can be represented by a Havriliak‐Negami (HN) relaxation branch parallel hopping conductivity. At high temperatures and low frequencies, the measured dielectric spectroscopy bends downward, which is caused by the electrode polarization. In this case, the equivalent dielectric model is composed of the body impedance of insulating paper and the electrode polarization in series. According to the equivalent dielectric model, the components of electrode polarization, hopping conductivity, and interface polarization can be separated, thereby eliminating the parasitic effect of electrode polarization on the dielectric properties of insulating paper. Both of hopping conductivity and interface polarization of insulating paper move toward high‐frequency direction with temperature increasing. For humid insulating paper with a moisture content of 5.9%, the activation energies of hopping conductivity and interface polarization are 1.18 and 0.99 eV, respectively. This difference in activation energies results in the inability of the spectrums of insulating paper to overlap with each other at different temperatures. Based on the insulating paper without oil immersion, the results obtained in this article are not affected by oil or oil‐immersion operations. This provides a reference for exploring the dielectric properties and physical mechanisms of oil‐paper composite insulation materials widely used in high‐voltage equipment. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Muscle strength, not muscle mass, determines the health-related quality of life in Indonesian women with systemic lupus erythematosus

ObjectiveNo study evaluated the impact of low muscle strength and mass on the Sarcopenia-related Quality of Life (SarQoL) in women with SLE.MethodsThis cross-sectional study recruited 145 women with SLE consecutively;...