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Sample records for bioelectrical impedance method

  1. [Abdomen specific bioelectrical impedance analysis (BIA) methods for evaluation of abdominal fat distribution].

    Science.gov (United States)

    Ida, Midori; Hirata, Masakazu; Hosoda, Kiminori; Nakao, Kazuwa

    2013-02-01

    Two novel bioelectrical impedance analysis (BIA) methods have been developed recently for evaluation of intra-abdominal fat accumulation. Both methods use electrodes that are placed on abdominal wall and allow evaluation of intra-abdominal fat area (IAFA) easily without radiation exposure. Of these, "abdominal BIA" method measures impedance distribution along abdominal anterior-posterior axis, and IAFA by BIA method(BIA-IAFA) is calculated from waist circumference and the voltage occurring at the flank. Dual BIA method measures impedance of trunk and body surface at the abdominal level and calculates BIA-IAFA from transverse and antero-posterior diameters of the abdomen and the impedance of trunk and abdominal surface. BIA-IAFA by these two BIA methods correlated well with IAFA measured by abdominal CT (CT-IAFA) with correlatipn coefficient of 0.88 (n = 91, p abdominal adiposity in clinical study and routine clinical practice of metabolic syndrome and obesity.

  2. Development of a new method for estimating visceral fat area with multi-frequency bioelectrical impedance

    International Nuclear Information System (INIS)

    Nagai, Masato; Komiya, Hideaki; Mori, Yutaka; Ohta, Teruo; Kasahara, Yasuhiro; Ikeda, Yoshio

    2008-01-01

    Excessive visceral fat area (VFA) is a major risk factor in such conditions as cardiovascular disease. In assessing VFA, computed tomography (CT) is adopted as the gold standard; however, this method is cost intensive and involves radiation exposure. In contrast, the bioelectrical impedance (BI) method for estimating body composition is simple and noninvasive and thus its potential application in VFA assessment is being studied. To overcome the difference in obtained impedance due to measurement conditions, we developed a more precise estimation method by selecting the optimum body posture, electrode arrangement, and frequency. The subjects were 73 healthy volunteers, 37 men and 36 women, who underwent CT scans to assess VFA and who were measured for anthropometry parameters, subcutaneous fat layer thickness, abdominal tissue area, and impedance. Impedance was measured by the tetrapolar impedance method using multi-frequency BI. Multiple regression analysis was conducted to estimate VFA. The results revealed a strong correlation between VFA observed by CT and VFA estimated by impedance (r=0.920). The regression equation accurately classified VFA≥100 cm 2 in 13 out of 14 men and 1 of 1 woman. Moreover, it classified VFA≥100 cm 2 or 2 in 3 out of 4 men and 1 of 1 woman misclassified by waist circumference (W) which was adopted as a simple index to evaluate VFA. Therefore, using this simple and convenient method for estimating VFA, we obtained an accurate assessment of VFA using the BI method. (author)

  3. Evaluation of segmental body composition by gender in obese children using bioelectric impedance analysis method

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    İhsan Çetin

    2015-12-01

    Full Text Available Objective: In this study, it was aimed to evaluate segmental body composition of children diagnosed with obesity using bioelectrical impedance analysis method in terms of different gender. Methods: 48 children, aged between 6-15 years, 21 of whom were boys while 27 were girls, diagnosed with obesity in Erciyes University Medical Faculty Department of Pediatric Endocrinology Outpatient Clinic were included in our study from April to June in 2011. Those over 95 percentile were defined as obese group. Tanita BC-418 device was used to analyze the body composition. Results: As a result of bioelectrical impedance analysis, lean body mass and body muscle mass were found to be statistically significantly higher in obese girls compared with obese boys. However, lean mass of the left arm, left leg muscle mass and basal metabolic rate were found to be statistically significantly lower in obese girls compared with obese boys. Conclusion: Consequently, it may be suggest that segmental analysis, where gender differences are taken into account, can provide proper exercise pattern and healthy way of weight loss in children for prevention of obesity and associated diseases including obesity and type 2 diabetics and cardiovascular diseases.

  4. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant...

  5. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    International Nuclear Information System (INIS)

    Li, Nan; Xu, Hui; Zhou, Zhou; Wang, Wei; Qiao, Guofeng; Li, David D-U

    2013-01-01

    A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz–10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications. (paper)

  6. Assessment of body composition by segmental bioelectrical impedance method in Japanese college athletes : focus on the different characteristic of sports

    OpenAIRE

    村松, 愛梨奈; 乙木, 幸道; 井川, 正治

    2013-01-01

    The purpose of this study was to clarify a characteristic of body composition of limbs in Japanese athletes by the segmental bioelectric impedance analysis (S-BIA) method. The subjects were 131 college athletes (baseball, volleyball, handball, combined competition, wrestling, soft tennis, swimming; athletes group) and 107 healthy college students (control group). The items of measurement were body height, body weight, BMI, percent of body fat (%FAT), skeletal muscle mass (SMM). We measured %F...

  7. Evaluation of the usefulness of visceral fat area measurement by the bioelectrical impedance method during workplace health screening

    International Nuclear Information System (INIS)

    Igarashi, Chiyo

    2008-01-01

    In the field of occupational health, health guidance concerning obesity is often conducted in order to prevent lifestyle-related diseases. With recent awareness of the concept of metabolic syndrome, measurement of the visceral fat area (VFA) by CT has been useful for health guidance, but it is difficult in workplace health screening. Presently, the BMI (Body Mass Index), body fat percentage measured by the bioelectrical impedance method, and waist girth at the umbilical level (abdominal girth) are practical indices of obesity used in such health screening. In this study, VAF was measured in 590 clerical or sales workers in the manufacturing industry using a body fat meter capable of a visceral fat measurement by the bioelectrical impedance method. The relationship of this value to the results of biochemical tests and lifestyle was then evaluated using analysis of covariance structures. Analysis indicated that the risk of lifestyle-related disease was closely related to the degree of obesity. Among indices of the degree of obesity, VFA was more closely related than BMI or body fat percentage, and only slightly less closely related than abdominal girth to the risk of lifestyle-related diseases. Since VFA is effective in screening for latent obesity, health guidance based on digital data, and the subjects' body imaging, its measurement by the bioelectrical impedance method is considered useful for workplace health management. (author)

  8. Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance

    Directory of Open Access Journals (Sweden)

    C.M.M. Resende

    2011-11-01

    Full Text Available The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA and the deuterium dilution method (DDM, to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg, fat-free mass (FFM; kg, and total body water (TBW; % determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001, FM (r = 0.93; P < 0.001 and TBW (r = 0.62; P < 0.001. The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg. TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.

  9. Gender differences and age-related changes in body fat mass in Tibetan children and teenagers: an analysis by the bioelectrical impedance method.

    Science.gov (United States)

    Zhang, Hai-Long; Fu, Qiang; Li, Wen-Hui; Liu, Su-Wei; Zhong, Hua; Duoji, Bai-Ma; Zhang, Mei-Zhi; Lv, Po; Xi, Huan-Jiu

    2015-01-01

    We aimed to obtain the fat base value and the fat distribution characteristics of Tibetan children and teenagers by estimating their body fat content with the bioelectrical impedance method. We recruited 1427 healthy children and teenagers by a stratified cluster sampling method. By using bioelectrical impedance analysis, we obtained various values relevant to fat. We found that total body fat mass and the fat mass of various body parts increased with age in boys and girls. Yet there were no differences between age groups until 11 years. However, fat mass increased quickly between 11 and 18 years, and significant differences were seen between adolescent boys and girls; all fat indices were higher in girls than in boys (pfat in Tibetan children and teenagers in Tibet is related to age and gender related hormone secretion, which reflects the physiological characteristics in different developmental stages.

  10. The comparative evaluation of patients′ body dry weight under hemodialysis using two methods: Bioelectrical impedance analysis and conventional method

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    Neda Alijanian

    2012-01-01

    Full Text Available Background: Dry weight (DW is an important concept related to patients undergoing hemodialysis. Conventional method seems to be time consuming and operator dependent. Bio impedance analysis (BIA is a new and simple method reported to be an accurate way for estimating DW. In this study, we aimed to compare the conventional estimation of DW with measuring DW by BIA. Materials and Methods: This study involved 130 uremic patients, performed in Isfahan, Iran. DW was calculated by both conventional (CDW and BIA (BIADW method and results were compared based on different grouping factors including sex, underlying cause of renal failure (RF (diabetic RF and non-diabetic RF, body mass index (BMI status, and sessions of hemodialysis. We also calculated the difference between DWs of 2 methods (DW diff = CDW-BIADW. Results: The mean of BIADW was significantly lower than CDW (57.20 ± 1.82 vs 59.36 ± 1.77, P value < 0.001. After grouping cases according to the underlying cause, BMI, sex, and dialysis sessions BIADW was significantly lower than CDW. Conclusion: Based on the combination of problems with CDW measurement which are corrected by BIA, and more clinical reliability of CDW, we concluded that although conventional method is a time-consuming and operator-dependent way to assess DW, DW could be estimated by combining both of these methods by finding the mathematic correlation between these methods.

  11. BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS

    Science.gov (United States)

    Loss of muscle mass and water shifts between body compartments are contributing factors to frailty in the elderly. The body composition changes are especially pronounced in institutionalized elderly. We investigated the ability of single-frequency bioelectrical impedance analysis (BIA) to identify b...

  12. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    Science.gov (United States)

    Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J

    2016-08-01

    Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment.

  13. Body composition of young people aged 17-18 years, practicing and not practicing swimming, with the use of the bioelectrical impedance method

    Directory of Open Access Journals (Sweden)

    Marek Jendrysek

    2015-11-01

    Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.

  14. BODY COMPOSITION OF YOUNG PEOPLE AGED 17-18 YEARS, PRACTICING AND NOT PRACTICING SWIMMING, WITH THE USE OF THE BIOELECTRICAL IMPEDANCE METHOD

    Directory of Open Access Journals (Sweden)

    Jendrysek Marek

    2015-11-01

    Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.

  15. Bioelectrical impedance analysis to estimate body composition in surgical and oncological patients: a systematic review

    NARCIS (Netherlands)

    Haverkort, E. B.; Reijven, P. L. M.; Binnekade, J. M.; de van der Schueren, M. A. E.; Earthman, C. P.; Gouma, D. J.; de Haan, R. J.

    2015-01-01

    Bioelectrical impedance analysis (BIA) is a commonly used method for the evaluation of body composition. However, BIA estimations are subject to uncertainties.The aim of this systematic review was to explore the variability of empirical prediction equations used in BIA estimations and to evaluate

  16. Bioelectrical impedance analysis of bovine milk fat

    Science.gov (United States)

    Veiga, E. A.; Bertemes-Filho, P.

    2012-12-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  17. Bioelectrical impedance analysis of bovine milk fat

    Energy Technology Data Exchange (ETDEWEB)

    Veiga, E A; Bertemes-Filho, P [Department of Electrical Eng., State University of Santa Catarina, Joinville (Brazil)

    2012-12-20

    Three samples of 250ml at home temperature of 20 Degree-Sign C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  18. Bioelectrical impedance analysis of bovine milk fat

    International Nuclear Information System (INIS)

    Veiga, E A; Bertemes-Filho, P

    2012-01-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  19. Bioelectrical impedance analysis for bovine milk: Preliminary results

    Science.gov (United States)

    Bertemes-Filho, P.; Valicheski, R.; Pereira, R. M.; Paterno, A. S.

    2010-04-01

    This work reports the investigation and analysis of bovine milk quality by using biological impedance measurements using electrical impedance spectroscopy (EIS). The samples were distinguished by a first chemical analysis using Fourier transform midinfrared spectroscopy (FTIR) and flow citometry. A set of milk samples (100ml each) obtained from 17 different cows in lactation with and without mastitis were analyzed with the proposed technique using EIS. The samples were adulterated by adding distilled water and hydrogen peroxide in a controlled manner. FTIR spectroscopy and flow cytometry were performed, and impedance measurements were made in a frequency range from 500Hz up to 1MHz with an implemented EIS system. The system's phase shift was compensated by measuring saline solutions. It was possible to show that the results obtained with the Bioelectrical Impedance Analysis (BIA) technique may detect changes in the milk caused by mastitis and the presence of water and hydrogen peroxide in the bovine milk.

  20. Effect of Intravenous Infusion Solutions on Bioelectrical Impedance Spectroscopy.

    Science.gov (United States)

    Yap, Jason; Rafii, Mahroukh; Azcue, Maria; Pencharz, Paul

    2017-05-01

    Bioelectrical impedance (BIA) is often used to measure body fluid spaces and thereby body composition. However, in acute animal studies, we found that impedance was driven by the saline content of intravenous (IV) fluids and not by the volume. The aim of the study was to investigate the effect of 3 different fluids acutely administered on the change in impedance, specifically resistance (R). Nine healthy adults participated in 3 treatment (0.9% saline, 5% dextrose, and a mixture of 0.3% saline + 3.3% dextrose) experiments on nonconsecutive days. They all received 1 L of one of the treatments intravenously over a 1-hour period. Repeated BIA measurements were performed prior to IV infusion and then every 5 minutes for the 1-hour infusion period, plus 3 more measurements up to 15 minutes after the completion of the infusion. The change in R in the 0.9% saline infusion experiment was significantly lower than that of the glucose and mixture treatment ( P < .001). Bioelectrical impedance spectroscopy and BIA measure salt rather than the volume changes over the infusion period. Hence, in patients receiving IV fluids, BIA of any kind (single frequency or multifrequency) cannot be used to measure body fluid spaces or body composition.

  1. Measuring body composition using the bioelectrical impedance method can predict the outcomes of gemcitabine-based chemotherapy in patients with pancreatobiliary tract cancer.

    Science.gov (United States)

    Muramatsu, Mami; Tsuchiya, Aya; Ohta, Seiko; Iijima, Yukie; Maruyama, Miyuki; Onodera, Yoshiko; Hagihara, Megumi; Nakaya, Naoki; Sato, Itaru; Omura, Kenji; Ueno, Soichiro; Nakajima, Hideo

    2015-12-01

    In order to examine the effect on body composition of anticancer drug treatments, the body composition rate in patients being treated with gemcitabine (GEM)-based chemotherapy was measured over time on an outpatient basis with a simple body composition monitor using the bioelectrical impedance (BI) method. The results revealed a significant reduction in the body fat rate (P=0.01) over the course of treatment in patients with pancreatobiliary tract cancer who became unable to continue GEM-based chemotherapy due to progressive disease or a decreased performance status. Meanwhile, no changes were observed in the body composition of control patients with urothelial carcinoma receiving GEM-based chemotherapy. In association with the adverse reactions to GEM and the hematotoxicity profile, a decreased white blood cell count was more likely to occur in body fat-dominant patients (mean fat rate, 25.8%; mean muscle rate, 26.2%), whereas a decreased blood platelet count was more likely to occur in skeletal muscle-dominant patients (mean fat rate, 23.3%; mean muscle rates, 28.7%). The correlation between body composition parameters and the relative dose intensity (RDI) associated with GEM administration was also analyzed. The results revealed a positive correlation between the RDI and basal metabolism amount (P=0.03); however, the RDI did not correlate with the body fat rate, skeletal muscle rate or body mass index (P=0.61, P=0.14 and P=0.20, respectively). In conclusion, the body composition rate measurement using the BI method over time may be useful for predicting the outcome of GEM-based chemotherapy and adverse events in patients with pancreatobiliary tract cancer. In particular, the present findings indicate that the changes in body fat rate may be helpful as an adjunct index for assessing potential continuation of chemotherapy and changes in physical conditions.

  2. Prediction of fat-free mass by bioelectrical impedance analysis in older adults from developing countries: a cross-validation study using the deuterium dilution method

    International Nuclear Information System (INIS)

    Mateo, H. Aleman; Romero, J. Esparza; Valencia, M.E.

    2010-01-01

    Objective: Several limitations of published bioelectrical impedance analysis (BIA) equations have been reported. The aims were to develop in a multiethnic, elderly population a new prediction equation and cross- validate it along with some published BIA equations for estimating fat-free mass using deuterium oxide dilution as the reference method. Design and setting: Cross-sectional study of elderly from five developing countries. Methods: Total body water (TBW) measured by deuterium dilution was used to determine fat-free mass (FFM) in 383 subjects. Anthropometric and BIA variables were also measured. Only 377 subjects were included for the analysis, randomly divided into development and cross-validation groups after stratified by gender. Stepwise model selection was used to generate the model and Bland Altman analysis was used to test agreement. Results: FFM = 2.95 - 3.89 (Gender) + 0.514 (Ht2/Z) + 0.090 (Waist) + 0.156 (Body weight). The model fit parameters were an R2, total F-Ratio, and the SEE of 0.88, 314.3, and 3.3, respectively. None of the published BIA equations met the criteria for agreement. The new BIA equation underestimated FFM by just 0.3 kg in the cross-validation sample. The mean of the difference between FFM by TBW and the new BIA equation were not significantly different; 95% of the differences were between the limits of agreement of -6.3 to 6.9 kg of FFM. There was no significant association between the mean of the differences and their averages (r= 0.008 and p= 0.2). Conclusions:This new BIA equation offers a valid option compared with some of the current published BIA equations to estimate FFM in elderly subjects from five developing countries. (Authors)

  3. Bioelectrical impedance vector distribution in the first year of life.

    Science.gov (United States)

    Savino, Francesco; Grasso, Giulia; Cresi, Francesco; Oggero, Roberto; Silvestro, Leandra

    2003-06-01

    We assessed the bioelectrical impedance vector distribution in a sample of healthy infants in the first year of life, which is not available in literature. The study was conducted as a cross-sectional study in 153 healthy Caucasian infants (90 male and 63 female) younger than 1 y, born at full term, adequate for gestational age, free from chronic diseases or growth problems, and not feverish. Z scores for weight, length, cranial circumference, and body mass index for the study population were within the range of +/-1.5 standard deviations according to the Euro-Growth Study references. Concurrent anthropometrics (weight, length, and cranial circumference), body mass index, and bioelectrical impedance (resistance and reactance) measurements were made by the same operator. Whole-body (hand to foot) tetrapolar measurements were performed with a single-frequency (50 kHz), phase-sensitive impedance analyzer. The study population was subdivided into three classes of age for statistical analysis: 0 to 3.99 mo, 4 to 7.99 mo, and 8 to 11.99 mo. Using the bivariate normal distribution of resistance and reactance components standardized by the infant's length, the bivariate 95% confidence limits for the mean impedance vector separated by sex and age groups were calculated and plotted. Further, the bivariate 95%, 75%, and 50% tolerance intervals for individual vector measurements in the first year of life were plotted. Resistance and reactance values often fluctuated during the first year of life, particularly as raw measurements (without normalization by subject's length). However, 95% confidence ellipses of mean vectors from the three age groups overlapped each other, as did confidence ellipses by sex for each age class, indicating no significant vector migration during the first year of life. We obtained an estimate of mean impedance vector in a sample of healthy infants in the first year of life and calculated the bivariate values for an individual vector (95%, 75%, and 50

  4. The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer

    OpenAIRE

    Gupta, Digant; Lis, Christopher G; Dahlk, Sadie L; King, Jessica; Vashi, Pankaj G; Grutsch, James F; Lammersfeld, Carolyn A

    2008-01-01

    Abstract Background Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as ei...

  5. Muscle development in healthy children evaluated by bioelectrical impedance analysis.

    Science.gov (United States)

    Uchiyama, Tomoka; Nakayama, Takahiro; Kuru, Satoshi

    2017-02-01

    This study aimed to use bioelectrical impedance analysis (BIA) to generate a new muscle density index (MDI), the MDI_BIA, to evaluate muscle development, and to demonstrate the changes that occur in the BIA-based muscle cross-sectional area index (MCAI_BIA) that accompany growth. We also sought to determine the traceability of chronological changes in the MDI_BIA and MCAI_BIA. Healthy children (n=112) aged 8.68±3.16years (0.33-14.00years) underwent bioelectrical impedance (BI) measurements of their upper arms, thighs, and lower legs. The MDI_BIA and MCAI_BIA were calculated, and cross-sectional investigations were conducted into the changes in these indices that accompanied growth. Data collected after 1.10±0.08years from 45 participants determined the traceability of the chronological changes in the MDI_BIA and MCAI_BIA. The MDI_BIA and MCAI_BIA were significantly positively correlated with age and height at all locations (Pchildren, and they showed significant chronological increases. Hence, these indices could be used to represent muscle development and muscle mass increases. BIA is non-invasive, convenient, and economical and it may be useful in evaluating muscle development and muscle cross-sectional areas in children. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  6. Bioelectrical impedance analysis for the prediction of hot carcass weight in buffalo calf

    Directory of Open Access Journals (Sweden)

    Leopoldo Iannuzzi

    2010-01-01

    Full Text Available Twenty young buffalo male calves were fed ad libitum with a total mix ration and with vitamin-mineral integration for 14 months. Seven days before slaughter, the animals were weighed and bioelectrical impedance measurements were collected in live animals. Physical and chemical characteristics were assessed on the Longissimus dorsi muscle after slaughter. Correlations and regression equations were calculated to determine the possible use of bioelectrical impedance for evaluating hot carcass weight. Bioelectrical impedance analysis at different frequencies, simple correlation and analysis of regression were examined for all the data collected, supporting the possibility of hot carcass weight prediction with equation at multifrequency. The results show that, probably due to the variability in animal live weight, the distribution of the colour parameters was not normally distributed. Moreover, using different frequencies of resistance and reactance, hot carcass weight in buffalo may be predicted with the following equation: Y=98.47–8.84(Rs100KHz+4.41(Rs1000 KHz-116.27(Xc5 KHz+51.04(Xc50 KHz+20.30(Xc100 KHz-33.92(Xc500 KHz+9.01(Xc1000 KHz±ε (Adjusted R Square value of .907 and SE of 5.728 However, further studies are required to improve the technique also in buffalo, after standardization of the method.

  7. Estimation of total body water by bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Kushner, R.F.; Schoeller, D.A.

    1986-01-01

    Total body water (TBW) measured by bioelectrical impedance analysis (BIA) was directly compared with deuterium-isotope dilution in a total of 58 subjects. First, sex-specific and group equations were developed by multiple regression analysis in (10 each) obese and nonobese men and women. Height/resistive impedance was the most significant variable used to predict deuterium-dilution space (D2O-TBW) and, combined with weight, yielded R = 0.99 and SE of estimate = 1.75 L. Equations predicted D2O-TBW equally well for obese and nonobese subjects. Second, the equations were prospectively tested in a heterogeneous group of 6 males and 12 females. Sex-specific equations predicted D2O-TBW with good correlation coefficients (0.96 and 0.93), total error (2.34 and 2.89 L), and a small difference between mean predicted and measured D2O-TBW (-1.4 +/- 2.05 and -0.48 +/- 2.83 L). BIA predicts D2O-TBW more accurately than weight, height, and/or age. A larger population is required to validate the applicability of our equations

  8. Body fat measurement by bioelectrical impedance and air displacement plethysmography: a cross-validation study to design bioelectrical impedance equations in Mexican adults

    Directory of Open Access Journals (Sweden)

    Valencia Mauro E

    2007-08-01

    Full Text Available Abstract Background The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP as standard method to measure body composition in Mexican adult men and women. Methods This study included 155 male and female subjects from northern Mexico, 20–50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg and height (Ht, cm were obtained by standard anthropometric techniques. Resistance, R (ohms and reactance, Xc (ohms were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM. Results and Discussion The final model was: FFM (kg = 0.7374 * (Ht2 /R + 0.1763 * (BW - 0.1773 * (Age + 0.1198 * (Xc - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE was 1.99 kg, and the pure error (PE was 2.96. There was no difference between FFM predicted by the new equation (48.57 ± 10.9 kg and that measured by ADP (48.43 ± 11.3 kg. The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 ± 2.84 kg. Conclusion The new bioelectrical impedance equation based on the two-compartment model (2C was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample.

  9. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities

    NARCIS (Netherlands)

    Havinga-Top, Thamar; Waninge, Aly; van der Schans, Cees; Jager, Harriët

    2015-01-01

    Background: Body composition measurements provide importanti nformation about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a

  10. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities

    NARCIS (Netherlands)

    Havinga-Top, A. M.; Waninge, A.; van der Schans, C. P.; Jager-Wittenaar, H.

    2015-01-01

    Background: Body composition measurements provide important information about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a

  11. Monitoring thoracic fluid content using bioelectrical impedance spectroscopy and Cole modeling

    NARCIS (Netherlands)

    Dovancescu, Silviu; Saporito, Salvatore; Herold, Ingeborg H.F.; Korsten, H.H.M.; Aarts, Ronald M.; Mischi, Massimo

    2017-01-01

    Heart failure is a chronic disease marked by frequenthospitalizations due to pulmonary fluid congestion. Monitoringthe thoracic fluid status may favor the detection of fluidcongestion in an early stage and enable targeted preventivemeasures. Bioelectrical impedance spectroscopy (BIS) has beenused in

  12. Is bioelectrical impedance accurate for use in large epidemiological studies?

    Directory of Open Access Journals (Sweden)

    Merchant Anwar T

    2008-09-01

    Full Text Available Abstract Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult. Bioelectrical impedance analysis (BIA is a relatively simple, quick and non-invasive technique, to measure body composition. It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large epidemiologic studies simpler surrogate techniques such as body mass index (BMI, waist circumference, and waist-hip ratio are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed systems such as foot (or hand-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are developed for different groups participating in the study.

  13. Knee bioelectric impedance assessment in healthy/with osteoarthritis subjects

    International Nuclear Information System (INIS)

    Neves, Eduardo Borba; Pino, Alexandre Visintainer; De Almeida, Renan Moritz Varnier Rodrigues; De Souza, Márcio Nogueira

    2010-01-01

    The present study analyzes parameters estimated by bioelectric impedance spectroscopy (BIS) in subjects with healthy and with osteoarthritis (OA) knees. Thirty-two male volunteers, members of the Parachute Military Infantry Brigade of Rio de Janeiro, Brazil, participated in the study (62 knee joints). Clinical specialists used the Dejour scale for OA classification and divided the subjects into a control (without OA) and a pathological group (with different degrees of OA). BIS data were obtained in a standing position using a BIS technique based on the current response to a step voltage excitation. Differences between groups were measured by means of a Wilcoxon–Mann–Whitney test. Results indicate that raw bioimpedance parameters seem to be sensitive to the physiological changes associated with OA. Thus, data indicate that extra-cellular resistance (Re) and reactance of the equivalent capacitance (Xcx) increase according to the disease intensity (p < 0.001). In conclusion, the BIS technique seems to be able to provide the objective and non-invasive basis for helping the diagnosis of knee OA

  14. The use of bioelectrical impedance analysis for body composition in epidemiological studies

    DEFF Research Database (Denmark)

    Böhm, A; Heitmann, B L

    2013-01-01

    BACKGROUND/OBJECTIVES: Bioelectrical impedance analysis (BIA) is a relatively simple, inexpensive and non-invasive technique to measure body composition and is therefore suitable in field studies and larger surveys. SUBJECTS/METHODS: We performed an overview of BIA-derived body fat percentages (BF......%) from 55 published studies of healthy populations aged 6-80 years. In addition, the relationship between body mass index (BMI) and body composition is documented in the context of BIA as a good alternative to closely differentiate which composition of the body better relates to the risk...

  15. Bioelectrics

    CERN Document Server

    Heller, Richard

    2017-01-01

    This book focuses on bioelectrics, a new multidisciplinary field encompassing engineering and biology with applications to the medical, environmental, food, energy, and biotechnological fields. At present, 15 universities and institutes in Japan, the USA and the EU comprise the International Consortium of Bioelectrics, intended to advance this novel and important research field. This book will serve as an introductory resource for young scientists and also as a textbook for use by both undergraduate and graduate students – the world’s first such work solely devoted to bioelectrics.

  16. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    International Nuclear Information System (INIS)

    Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A.

    1990-01-01

    The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition

  17. Bioelectrical impedance analysis to define an excess of body fat: evaluation in patients with psoriasis.

    Science.gov (United States)

    Galluzzo, M; Talamonti, M; Perino, F; Servoli, S; Giordano, D; Chimenti, S; De Simone, C; Peris, K

    2017-06-01

    There is strong evidence that obesity is closely associated with psoriasis. However, data on body composition are lacking in psoriasis. The purpose of this study were to investigate the body composition in psoriasis patients using bioelectrical impedance analysis and to correlate the bioelectrical impedance data with disease severity and laboratory parameters. Anthropometric measurements and bioelectrical impedance analyses were performed on patients with psoriasis, naïve to any systemic treatment, who attended the outpatient clinics of two University centers. Data of 164 adult patients were analyzed. Compared to men, women had several significantly higher bioelectrical impedance parameters including reactance, fat mass% and adipose tissue%. The values of adipose tissue were positively correlated only with patients age (p = .021) and age at disease onset (p = .0006), but not with disease severity. In addition, we observed that the use of BMI cutoffs allowed to categorize 36.7% of women and 19.2% of men as obese, while fat mass% showed that 53.3% of women and 48.1% of men were obese. In our study, psoriasis is been associated with a high fat mass%. We suggest that screening for body fat distribution in psoriatic patients might be useful to identify early obesity-related disease.

  18. The validity and accuracy in foot-to-foot bioelectrical impedance ...

    African Journals Online (AJOL)

    The validity and accuracy in foot-to-foot bioelectrical impedance analysis measuring models referenced by dual-energy X-ray absorptiometry in body composition in standing position. KC Hsieh, HK Lu, CH Chen, TR Jang, YY Chen, MF Kao ...

  19. Impact of hemodialysis on dual X-ray absorptiometry, bioelectrical impedance measurements, and anthropometry

    DEFF Research Database (Denmark)

    Abrahamsen, Bo; Hansen, T B; Høgsberg, I M

    1996-01-01

    ), bioelectrical impedance analysis (BIA), and simple anthropometry in 19 patients (9 women and 10 men, mean age 46 y) before and after hemodialysis, removing 0.9-4.3 L (x: 2.8L) of ultrafiltrate. The reduction in fat-free mass (FFM) measured by DXA was highly correlated with the ultrafiltrate, as determined...... by the reduction in gravimetric weight (r = 0.975, P FFM reductions (r = 0.66, P ..., was estimated to be 0.6% lower after dialysis. None of the simple anthropometric measurements correlated significantly with the reduction in FFM. In an unmodified clinical setting, DXA appears to be superior to other simple noninvasive methods for determining body composition, particularly when the emphasis...

  20. Lipid and moisture content modeling of amphidromous Dolly Varden using bioelectrical impedance analysis

    Science.gov (United States)

    Stolarski, J.T.; Margraf, F.J.; Carlson, J.G.; Sutton, T.M.

    2014-01-01

    The physiological well-being or condition of fish is most commonly estimated from aspects of individual morphology. However, these metrics may be only weakly correlated with nutritional reserves stored as lipid, the primary form of accumulated energy in fish. We constructed and evaluated bioelectrical impedance analysis (BIA) models as an alternative method of assessing condition in amphidromous Dolly Varden Salvelinus malma collected from nearshore estuarine and lotic habitats of the Alaskan Arctic. Data on electrical resistance and reactance were collected from the lateral and ventral surfaces of 192 fish, and whole-body percent lipid and moisture content were determined using standard laboratory methods. Significant inverse relationships between temperature and resistance and reactance prompted the standardization of these data to a constant temperature using corrective equations developed herein. No significant differences in resistance or reactance were detected among spawning and nonspawning females after accounting for covariates, suggesting that electrical pathways do not intersect the gonads. Best-fit BIA models incorporating electrical variables calculated from the lateral and ventral surfaces produced the strongest associations between observed and model-predicted estimates of proximate content. These models explained between 6% and 20% more of the variability in laboratory-derived estimates of proximate content than models developed from single-surface BIA data and 32% more than models containing only length and weight data. While additional research is required to address the potential effects of methodological variation, bioelectrical impedance analysis shows promise as a way to provide high-quality, minimally invasive estimates of Dolly Varden lipid or moisture content in the field with only small increases in handling time.

  1. Can abdominal bioelectrical impedance refine the determination of visceral fat from waist circumference?

    International Nuclear Information System (INIS)

    Watson, S; Blundell, H L; Evans, W D; Griffiths, H; Newcombe, R G; Rees, D A

    2009-01-01

    Ryo et al (2005 Diabetes Care 28 451–3) reported a new method for measuring the visceral fat area (VFA) by combining abdominal bioelectrical impedance analysis (BIA) with measurement of waist circumference (WC), but very few methodological details were provided. Furthermore, the study did not test the use of WC alone as an indicator of VFA even though others had previously reported a strong correlation. We sought to determine the optimal measurement technique and analysis for measuring VFA by abdominal BIA and WC. 18 volunteers (age 23–64 years) underwent measurement of WC, abdominal impedance (Bodystat 500 four-electrode system) and a single cross-sectional CT scan at the umbilicus. VFA derived using WC 3 and measurements of abdominal impedance from electrode pairs sited at the flank predicted the value of VFA measured by CT with correlation r = 0.904 (p 1.9 alone, without involving BIA at all, provided a similar correlation (r = 0.923). Our small preliminary study shows that abdominal BIA is potentially a practicable non-invasive technique for measurement of VFA but casts doubt on whether it adds any value to the use of WC alone. Larger studies are now required to test this finding. (note)

  2. [Resting metabolic rate estimated by bioelectrical impedance analysis and its determinants in maintenance hemodialysis patients].

    Science.gov (United States)

    Da, J J; Peng, H Y; Lin, X; Shen, Y; Zhao, J Q; He, S; Zha, Y

    2018-03-27

    Objective: To explore the level of resting energy expenditure (REE) estimated by bioelectrical impedance analysis and the association of resting metabolic rate (RMR) with clinical related factors, and provide new ideas for improving protein energy wasting (PEW) in maintenance hemodialysis (MHD) patients. Methods: Seven hundred and sixty-five subjects receiving MHD between July 2015 and September 2016 in 11 hemodialysis centers in Guizhou province were enrolled in this cross-sectional study. Bioelectrical impedance analysis was used to measure RMR and body composition, such as lean body mass, fat mass and body cell mass (BCM). Baseline characteristics, routine blood test indexes and biochemical data of hemodialysis patients were collected. The level of RMR and body composition in hemodialysis patients was compared by gender grouping. Then the patients were divided into four groups according to the cutoff value of RMR quartile. Spearman correlation analysis and multiple linear regression analysis were used to analyze the relationships between RMR and clinical related factors. Results: The average age of MHD patients was (54.96±15.78) years and the duriation of dialysis was (42.3±9.0) months. The level of RMR in male patients (474 cases, 61.96%) was significantly higher than that in female patients [1 591(1 444, 1 764) kcal/d vs 1 226 (1 104, 1 354) kcal/d, P lean body mass ( P =0.193). Multiple linear regression analysis showed that RMR was positively correlated with body surface area (β=0.817) and lactate dehydrogenase (LDH) (β=0.198), and negatively correlated with age (β=-0.141), all P maintenance hemodialysis are associated with lactate dehydrogenase level, which may become a new index to evaluate energy consumption.

  3. Application of bioelectrical impedance analysis in prediction of light kid carcass and muscle chemical composition.

    Science.gov (United States)

    Silva, S R; Afonso, J; Monteiro, A; Morais, R; Cabo, A; Batista, A C; Guedes, C M; Teixeira, A

    2018-06-01

    Carcass data were collected from 24 kids (average live weight of 12.5±5.5 kg; range 4.5 to 22.4 kg) of Jarmelista Portuguese native breed, to evaluate bioelectrical impedance analysis (BIA) as a technique for prediction of light kid carcass and muscle chemical composition. Resistance (Rs, Ω) and reactance (Xc, Ω), were measured in the cold carcasses with a single frequency bioelectrical impedance analyzer and, together with impedance (Z, Ω), two electrical volume measurements (VolA and VolB, cm2/Ω), carcass cold weight (CCW), carcass compactness and several carcass linear measurements were fitted as independent variables to predict carcass composition by stepwise regression analysis. The amount of variation explained by VolA and VolB only reached a significant level (Pcarcass fat weight (0.814⩽R 2⩽0.862; Pcarcass fat weight (combined with carcass length, CL; R 2=0.943; Pcarcass composition.

  4. Bioelectrical impedance vector analysis (BIVA for measuring the hydration status in young elite synchronized swimmers.

    Directory of Open Access Journals (Sweden)

    Marta Carrasco-Marginet

    Full Text Available The assessment of body hydration is a complex process, and no measurement is valid for all situations. Bioelectrical impedance vector analysis (BIVA has emerged as a relatively novel technique for assessing hydration status in sports. We applied BIVA a to determine hydration changes evoked by an intense synchronized swimming (SS training session; b to characterize the sample of young elite swimmers in relation with a nonathletic reference population; and c to generate its 50%, 75% and 95% percentiles of the bioelectrical variables.Forty-nine elite SS female swimmers of two age categories, comen (Co: 13.9 ± 0.9 years, n = 34 and junior (Jr: 16.3 ± 0.6 years, n = 15, performed a long, high intensity training session. Body mass (BM and bioelectrical variables (R, resistance; Xc, reactance; PA, phase angle; and Z, impedance module were assessed pre- and post-training. BIVA was used to characterize 1 the distribution pattern of the bioelectrical vector (BIA vector for both age groups, and 2 pre- to post-training BIA vector migration. Bioelectrical variables were also correlated with BM change values.Most swimmers were mostly located outside the 75% and some beyond the 95% percentile of the bioelectrical tolerance ellipses of the general population. The BIA vector showed statistically significant differences in both Co (T2 = 134.7, p = 0.0001 and Jr (T2 = 126.2, p < 0.001. Both groups were also bioelectrically different (T2 = 17.6, p < 0.001. After the training session, a decrease in BM (p = 0.0001 and an increase in BIA variables (p = 0.01 was observed. BIVA also showed a significant pre-post vector migration both in Co (T2 = 82.1; p < 0.001 and Jr (T2 = 41.8; p < 0.001. No correlations were observed between BM changes and bioelectrical variables.BIVA showed specific bioelectrical characteristics in young elite SS athletes. Considering the decrease in BM and the migration of the BIA vector, we conclude that the homeostatic hydration status of these

  5. Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study

    NARCIS (Netherlands)

    Hofsteenge, G.H.; Chin A Paw, M.J.M.; Weijs, P.J.M.

    2015-01-01

    Background: In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11-18 years) compared to

  6. The Effect of an Acute After-School Exercise Bout on Percentage of Body Fat Using Leg-to-Leg Bioelectrical Impedance Analysis in Children

    Science.gov (United States)

    Andreacci, Joseph L.; Dixon, Curt B.; Rompolski, Krista; VanGorden, Kelly M.

    2008-01-01

    Bioelectrical impedance analysis (BIA) is a fast, easy to administer, and relatively inexpensive method of evaluating body composition. Due to the ease of operation, interest in using BIA to estimate percentage of body fat (%BF) has grown, especially in settings where body composition assessments are often performed without the benefit of…

  7. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    DEFF Research Database (Denmark)

    Ejlerskov, Katrine Tschentscher; Jensen, Signe Marie; Christensen, Line B

    2014-01-01

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99......-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2-4 years...

  8. Hydration in advanced cancer: can bioelectrical impedance analysis improve the evidence base? A systematic review of the literature.

    Science.gov (United States)

    Nwosu, Amara Callistus; Mayland, Catriona R; Mason, Stephen R; Khodabukus, Andrew F; Varro, Andrea; Ellershaw, John E

    2013-09-01

    Decisions surrounding the administration of clinically assisted hydration to patients dying of cancer can be challenging because of the limited understanding of hydration in advanced cancer and a lack of evidence to guide health care professionals. Bioelectrical impedance analysis (BIA) has been used to assess hydration in various patient groupings, but evidence for its use in advanced cancer is limited. To critically appraise existing methods of hydration status assessment in advanced cancer and review the potential for BIA to assess hydration in advanced cancer. Searches were carried out in four electronic databases. A hand search of selected peer-reviewed journals and conference abstracts also was conducted. Studies reporting (de)hydration assessment (physical examination, biochemical measures, symptom assessment, and BIA) in patients with advanced cancer were included. The results highlight how clinical examination and biochemical tests are standard methods of assessing hydration, but limitations exist with these methods in advanced cancer. Furthermore, there is disagreement over the evidence for some commonly associated symptoms with dehydration in cancer. Although there are limitations with using BIA alone to assess hydration in advanced cancer, analysis of BIA raw measurements through the method of bioelectrical impedance vector analysis may have a role in this population. The benefits and burdens of providing clinically assisted hydration to patients dying of cancer are unclear. Bioelectrical impedance vector analysis shows promise as a hydration assessment tool but requires further study in advanced cancer. Innovative methodologies for research are required to add to the evidence base and ultimately improve the care for the dying. Copyright © 2013 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

  9. Impact of eating and drinking on body composition measurements by bioelectrical impedance.

    Science.gov (United States)

    Androutsos, O; Gerasimidis, K; Karanikolou, A; Reilly, J J; Edwards, C A

    2015-04-01

    Bioelectrical impedance analysis would be a more practical tool to measure body composition in clinical settings, dietetic practice and epidemiological studies if patients/subjects did not have to fast before measurements. The present study assessed whether the ingestion of food or drink had any biologically significant effect on bioimpedance measurements and body composition by the foot-to-foot method. Fifty-five healthy adults [30 males and 25 females; mean (SD) age 27.7 (7.1) years; mean (SD)body mass index 24 (3.8) kg m(-2)] were randomly assigned to a 2-day food trial (high-fat meal or high-carbohydrate meal) or a 2-day drink trial (water or high electrolyte drink). Body composition measurements were carried out in the fasting state, immediately after meal consumption and every 30 min for 2 h by the foot-to-foot single frequency bioimpedance technique. Bioimpedance increased significantly after the ingestion of food and fluid, although the changes were small. The electrolyte drink, high-fat and high-carbohydrate meals significantly increased the percentage body fat and fat mass. In all cases, the median percentage changes from baseline were approximately 1% in body fat percentage units. Although there were statistically significant changes in body composition estimates after food or drink consumption, these were small and within the imprecision of the impedance technique, and so are unlikely to be of clinical significance. The present study suggests that impedance measures of body fatness in clinical settings do not require strict adherence to fasting, and this should increase the opportunities for clinical application. © 2014 The British Dietetic Association Ltd.

  10. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

    Directory of Open Access Journals (Sweden)

    Raquel D. Langer

    2016-03-01

    Full Text Available Background: Bioelectrical Impedance Analysis (BIA is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA as a reference method. Student’s t-test (for paired sample, linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05 and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.

  11. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets.

    Science.gov (United States)

    Langer, Raquel D; Borges, Juliano H; Pascoa, Mauro A; Cirolini, Vagner X; Guerra-Júnior, Gil; Gonçalves, Ezequiel M

    2016-03-11

    Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. A total of 396 males, Brazilian Army cadets, aged 17-24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student's t-test (for paired sample), linear regression analysis, and Bland-Altman method were used to test the validity of the BIA equations. Predictive BIA equations showed significant differences in FFM compared to DXA (p FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.

  12. Percentiles of body fat measured by bioelectrical impedance in children and adolescents from Bogotá (Colombia): the FUPRECOL study.

    Science.gov (United States)

    Escobar-Cardozo, Germán D; Correa-Bautista, Jorge E; González-Jiménez, Emilio; Schmidt-RioValle, Jacqueline; Ramírez-Vélez, Robinson

    2016-04-01

    The analysis of body composition is a fundamental part of nutritional status assessment. The objective of this study was to establish body fat percentiles by bioelectrical impedance in children and adolescents from Bogotá (Colombia) who were part of the FUPRECOL study (Asociación de la Fuerza Prensil con Manifestaciones Tempranas de Riesgo Cardiovascular en Niños y Adolescentes Colombianos - Association between prehensile force and early signs of cardiovascular risk in Colombian children and adolescents). This was a cross-sectional study conducted among 5850 students aged 9-17.9 years old from Bogotá (Colombia). Body fat percentage was measured using foot-to-foot bioelectrical impedance (Tanita®, BF-689), by age and gender. Weight, height, waist circumference, and hip circumference were measured, and sexual maturity was self-staged. Percentiles (P3, P10, P25, P50, P75, P90 and P97) and centile curves were estimated using the LMS method (L [BoxCox curve], M [median curve] and S [variation coefficient curve]), by age and gender. Subjects included were 2526 children and 3324 adolescents. Body fat percentages and centile curves by age and gender were established. For most age groups, values resulted higher among girls than boys. Participants with values above P90 were considered to have a high cardiovascular risk due to excess fat (boys > 23.428.3, girls > 31.0-34.1). Body fat percentage percentiles measured using bioelectrical impedance by age and gender are presented here and may be used as reference to assess nutritional status and to predict cardiovascular risk due to excess fat at an early age. Sociedad Argentina de Pediatría.

  13. Validation of a portable bioelectrical impedance analyzer for the assessment of body composition.

    Science.gov (United States)

    Karelis, Antony D; Chamberland, Gabriel; Aubertin-Leheudre, Mylène; Duval, Christian

    2013-01-01

    One of the major challenges in field research has been the difficulty to adequately measure body composition, such as % body fat and fat-free mass (FFM). Therefore, the purpose of the present study was to investigate the convergent validity of the portable bioelectrical impedance body composition analyzer, the Inbody 230, with dual X-ray absorptiometry (DXA) (General Electric Lunar Prodigy). The study population consisted of 145 men and women (age, 44.6 ± 20 years; BMI, 24.5 ± 3.8 kg·m(-2)). We measured body composition (fat mass, % body fat, total FFM, trunk FFM, and appendicular FFM) using DXA and the Inbody 230. Results show strong significant correlations between both methods for fat mass, % body fat, total FFM, and trunk FFM (r = 0.94-0.99). Furthermore, we showed a modest significant correlation between both methods for appendicular FFM (r = 0.63). Finally, as shown by Bland-Altman analysis, no significant biases were observed between Inbody 230 and DXA for fat mass, % body fat, and total FFM. However, trunk and appendicular FFM were shown to have significant biases between the Inbody 230 and DXA. In conclusion, the present study indicated that the portable Inbody 230 may be an acceptable device to measure fat mass, % body fat, and total FFM (except for women) in healthy adults. In addition, there appears to be a systematic bias for the estimation of trunk and appendicular FFM with the Inbody 230 in men and women.

  14. Bioelectrical impedance analysis for diagnosing sarcopenia and cachexia: what are we really estimating?

    Science.gov (United States)

    Gonzalez, Maria Cristina; Heymsfield, Steven B

    2017-04-01

    As reference methods are not available for identifying low skeletal muscle mass in clinical practice, the European Group on Sarcopenia in Older People the Asian Working Group for Sarcopenia and the International Consensus for Cancer Cachexia guidelines accept bioelectrical impedance analysis (BIA) as an option for sarcopenia and cachexia assessment. Using different BIA equations, several components that represent 'muscularity' can be assessed. Total skeletal muscle mass or appendicular skeletal muscle mass normalized in relation to height (skeletal muscle mass index or appendicular skeletal muscle index, respectively) is the most common term used in the consensus. These terms are similar, but they should not be used as synonymous. Both terms can be used to define sarcopenia, but adequate equations and cut-off values should be used according to the studied population. However, there is a disagreement between the sarcopenia definition assessed by using BIA from the European Group on Sarcopenia in Older People and Cachexia Consensus, and this can lead to an overestimation of sarcopenia and, consequently, cachexia. An effort should be made to standardize the terminology employed by the Societies to define low muscularity and sarcopenia by using BIA. Future validation studies may show the need for specific cut-off values for each population using this method. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  15. Bioelectrical impedance vector analysis for evaluating zinc supplementation in prepubertal and healthy children

    Directory of Open Access Journals (Sweden)

    Márcia Marília Gomes Dantas

    2015-09-01

    Full Text Available Background: The prevalence of abnormal nutritional status has increased in children and adolescents. Nutritional assessment is important for monitoring the health and nutritional status. Bioelectrical impedance vector analysis (BIVA combines changes in tissue hydration and structure and body composition that can be assessed. Objectives: The objective of this study was to use BIVA to evaluate nutritional status in 60 prepubertal children, aged between 8 and 9 years, supplemented with zinc, to detect possible changes in body composition. Design: We performed a randomized, controlled, triple-blind study. The children were divided into the control group (CG; sorbitol 10%, n=29 or the experimental group (EG; 10 mg Zn/day, n=31, and the duration of the experiment was 3 months. Anthropometric assessments were performed for all of the children. Results: The body mass index-for-age increased after oral zinc supplementation in the EG (p=0.005. BIVA indicated that the CG demonstrated a tendency for dehydration and decreased soft tissue and the EG demonstrated a tendency for increased soft tissue, primarily the fat-free mass. After analyses of BIVA ellipses, we observed that this method could detect improvements in body composition in healthy children supplemented with zinc. Conclusions: These results suggest that BIVA could be an auxiliary method for studying a small population undergoing zinc intervention.

  16. Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

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    de Blasio F

    2016-09-01

    Full Text Available Francesca de Blasio,1 Francesco de Blasio,2,3 Giulia Miracco Berlingieri,2 Andrea Bianco,3,4 Marta La Greca,1 Frits M E Franssen,5 Luca Scalfi1 1Department of Public Health, Medical School, “Federico II” University of Naples, 2Respiratory Medicine and Pulmonary Rehabilitation Section, Clinic Center, Private Hospital, Naples, 3Department of Medicine and Health Sciences “V Tiberio”, University of Molise, Campobasso, 4Department of Cardio-Thoracic and Respiratory Sciences, Second University of Naples, Naples, Italy; 5Department of Research and Education, CIRO, Horn, the NetherlandsBackground: Multifrequency bioelectrical impedance analysis (MF-BIA is a technique that measures body impedance (Z at different frequencies (5, 10, 50, 100, and 250 kHz. Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality.Objectives: To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients.Methods: MF-BIA was performed (Human Im-Touch analyzer in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients.Results: After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001 and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively. Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001, 6-minute walk distance (P<0.005, respiratory muscle strength (P<0.005, forced

  17. The diagnostic accuracy of multi-frequency bioelectrical impedance analysis in diagnosing dehydration after stroke

    Science.gov (United States)

    Kafri, Mohannad W.; Myint, Phyo Kyaw; Doherty, Danielle; Wilson, Alexander Hugh; Potter, John F.; Hooper, Lee

    2013-01-01

    Background Non-invasive methods for detecting water-loss dehydration following acute stroke would be clinically useful. We evaluated the diagnostic accuracy of multi-frequency bioelectrical impedance analysis (MF-BIA) against reference standards serum osmolality and osmolarity. Material/Methods Patients admitted to an acute stroke unit were recruited. Blood samples for electrolytes and osmolality were taken within 20 minutes of MF-BIA. Total body water (TBW%), intracellular (ICW%) and extracellular water (ECW%), as percentages of total body weight, were calculated by MF-BIA equipment and from impedance measures using published equations for older people. These were compared to hydration status (based on serum osmolality and calculated osmolarity). The most promising Receiver Operating Characteristics curves were plotted. Results 27 stroke patients were recruited (mean age 71.3, SD10.7). Only a TBW% cut-off at 46% was consistent with current dehydration (serum osmolality >300 mOsm/kg) and TBW% at 47% impending dehydration (calculated osmolarity ≥295–300 mOsm/L) with sensitivity and specificity both >60%. Even here diagnostic accuracy of MF-BIA was poor, a third of those with dehydration were wrongly classified as hydrated and a third classified as dehydrated were well hydrated. Secondary analyses assessing diagnostic accuracy of TBW% for men and women separately, and using TBW as a percentage of lean body mass showed some promise, but did not provide diagnostically accurate measures across the population. Conclusions MF-BIA appears ineffective at diagnosing water-loss dehydration after stroke and cannot be recommended as a test for dehydration, but separating assessment by sex, and using TBW as a percentage of lean body weight may warrant further investigation. PMID:23839255

  18. The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity

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    Marini E

    2012-12-01

    Full Text Available Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity.Subjects and methods: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The “classic” and “specific” BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student’s t-test and Hotelling’s T2 test, as well as Pearson’s correlation coefficient.Results: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01 and impedance/height (Z/H; p < 0.01, and a lower phase angle (p < 0.01. Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T2 = 15.7, p < 0.01; women: T2 = 10.7, p < 0.01, with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01. Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T2 = 13.4, p < 0.01, mainly due to the higher values of specific R in sarcopenic obese individuals.Conclusion: BIVA detected

  19. Adiposity and postural balance control: correlations between bioelectrical impedance and stabilometric signals in elderly Brazilian women

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    Míriam Raquel Meira Mainenti

    2011-01-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the correlation between body adiposity and postural control in elderly women. INTRODUCTION: Aging and obesity account for a significant portion of healthcare spending. Life expectancy is increasing worldwide, and Rio de Janeiro has the largest proportion of elderly residents of all Brazilian states. METHODS: A total of 45 women underwent bioelectrical impedance analysis, waist circumference measurements, weight and height measurements, and stabilometric tests in eight different stance conditions (opened and closed bases with both eyes opened and closed and right and left tandem and unilateral stances with eyes opened. During unilateral stances, the number of hand or foot contacts was counted. RESULTS: Weight, body mass index, waist circumference, fat percentage, and fat mass showed statistically significant (p,0.05 and positive correlations with the number of contacts made during unilateral stances. The subjects with greater fat mass showed significantly higher anterior-posterior standard deviation and range when their eyes were closed. The sway area was also greater for this group in opened base when their eyes were closed. DISCUSSION: The results relating body adiposity and postural control can be explained by the difficulty of maintaining a greater quantity of body fat mass within the limits of the individual support base, especially while assuming a unilateral stance. CONCLUSION: The subjects with a greater fat mass exhibited poor balance control, indicating that body adiposity level was associated with postural control in the elderly women examined in the present study.

  20. Sex and age specific prediction formulas for estimating body composition from bioelectrical impedance : a cross-validation study

    NARCIS (Netherlands)

    Deurenberg, P.; van der Kooy, K; Leenen, R; Weststrate, J A; Seidell, J C

    In 827 male and female subjects, with a large variation in body composition and an age range of 7-83 years, body composition was measured by densitometry, anthropometry and bioelectrical impedance. The relationship between densitometrically determined fat free mass (FFM) with body impedance (R),

  1. [Assessing nutritional status of severe malnutrition patients by bioelectrical impedance technique: a multicenter prospective study].

    Science.gov (United States)

    Li, Qiang; Li, Xueni; Leng, Yuxin; Zhu, Xi; Yao, Gaiqi

    2018-02-01

    To assess the nutritional status of severe malnutrition patients with anorexia nervosa by multi-frequency bioelectrical impedance technique, and to provide the basis for nutritional support therapy. A prospective study was conducted. Twenty-six severe malnutrition patients with anorexia nervosa, body mass index (BMI) ≤ 16 kg/m 2 admitted to intensive care unit (ICU) of Peking University Third Hospital and general three ward of Peking University Sixth Hospital from June 1st to September 30th, 2017 were enrolled. The extracellular water (ECW), intracellular water (ICW), ECW/ICW ratio, adipose tissue mass (ATM), lean tissue mass (LTM), total body water/body weight (TBW/WT), ATM/WT, and LTM/WT were measured by multi-frequency bioelectrical impedance meter. Thirty-eighty healthy volunteers with normal nutritional status (23.0 kg/m 2 > BMI > 18.5 kg/m 2 ) matched by gender and height were enrolled as healthy control group. The predictive value of main body composition for nutritional status were analyzed by receiver operating characteristic (ROC) curve. All the patients were female. There was no significant difference in height between two groups, but WT and BMI in the severe malnutrition group were significantly higher than those in the healthy control group [WT (kg): 38.1±4.9 vs. 54.2±3.3, BMI (kg/m 2 ): 13.6±2.5 vs. 21.2±1.1, both P anorexia nervosa changed significantly. Bioelectrical impedance technology can be an effective assessment tool for the nutritional status of such patients.

  2. Estimation of body fat from anthropometry and bioelectrical impedance in Native American children.

    Science.gov (United States)

    Lohman, T G; Caballero, B; Himes, J H; Davis, C E; Stewart, D; Houtkooper, L; Going, S B; Hunsberger, S; Weber, J L; Reid, R; Stephenson, L

    2000-08-01

    Obesity, as measured by body mass index, is highly prevalent in Native American children, yet there are no valid equations to estimate total body fatness for this population. This study was designed to develop equations to estimate percentage body fat from anthropometry and bioelectrical impedance as a critical part of Pathways, a multi-site study of primary prevention of obesity in Native American children. Percentage fat was estimated from deuterium oxide dilution in 98 Native American children (Pima/Maricopa, Tohono O'odham and White Mountain Apache tribes) between 8 and 11 y of age. The mean fat content (38.4%+/-8. 1%) was calculated assuming the water content of the fat-free body was 76%. Initial independent variables were height, weight, waist circumference, six skinfolds and whole-body resistance and reactance from bioelectrical impedance (BIA). Using all-possible-subsets regressions with the Mallows C (p) criterion, and with age and sex included in each regression model, waist circumference, calf and biceps skinfolds contributed least to the multiple regression analysis. The combination of weight, two skinfolds (any two out of the four best: triceps, suprailiac, subscapular and abdomen) and bioelectrical impedance variables provided excellent predictability. Equations without BIA variables yielded r2 almost as high as those with BIA variables. The recommended equation predicts percentage fat with a root mean square error=3.2% fat and an adjusted r2=0.840. The combination of anthropometry and BIA variables can be used to estimate total body fat in field studies of Native American children. The derived equation yields considerably higher percentage fat values than other skinfold equations in children.

  3. Comparison of body fat using various bioelectrical impedance analyzers in university students

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    Petr Kutáč

    2015-12-01

    Full Text Available Background: At present, the portfolio of devices using the bioelectrical impedance (BIA method is continuously expanding as a result of the wide use of this method in the field as measurements by this method are fast and staff training is simple and reasonably priced. Nonetheless, the problem is that despite using the same method, bioimpedance analyzers can differ in many parameters. They use different electric current frequencies, a different number of electrodes and the electric current may be conducted through different parts of the body.Objective: The main objective of the study is to compare and evaluate the differences of values of the analysis of the body fat of university students measured by BIA analyzers that differ in the applied electric current frequency, number of electrodes and flow of the electric current through the individual body parts.Methods: The research included 125 participants (70 male and 55 female. The measurements were taken by the following analyzers: Tanita 418 MA, InBody 720, InBody R20 and Omron BF 300.Results: The differences in the mean values of the body fat representation between the used analyzers in men ranged from 0.1 to 3.4% and from 0.0 to 2.4 kg, in women from 0.5 to 6.5% and from 0.4 to 3.8 kg in relation to the used analyzer.Conclusions: In men with regular physical activity, the values measured by InBody R20 were statistically and practically different. The analyzer measured higher values that other analyzers. In women, there were statistically and practically significant differences in the values measured by Omron BF 300. This analyzer measured lower values than other analyzers.

  4. Validation of bioelectrical impedance analysis in Ethiopian adults with HIV

    DEFF Research Database (Denmark)

    Hegelund, Maria H; Wells, Jonathan C; Girma, Tsinuel

    2017-01-01

    in populations of different ethnic origin and health status. The aim of the present study was to test the validity of BIA in Ethiopian antiretroviral-naive HIV patients. BIA was validated against the 2H dilution technique by comparing fat-free mass (FFM) measured by the two methods using paired t tests and Bland...... % were underweight with a BMI below 18·5 kg/m2. There were no differences in FFM between the methods. Overall, BIA slightly underestimated FFM by 0·1 kg (-0·1, 95 % CI -0·3, 0·2 kg). The Bland-Altman plot indicated acceptable agreement with an upper limit of agreement of 4·5 kg and a lower limit...... of agreement of -4·6 kg, but with a small correlation between the mean difference and the average FFM. BIA slightly overestimated FFM at low values compared with the 2H dilution technique, while it slightly underestimated FFM at high values. In conclusion, BIA proved to be valid in this population and may...

  5. Use of electrocardiogram (ECG) electrodes for Bioelectrical Impedance Analysis (BIA)

    International Nuclear Information System (INIS)

    Caicedo-Eraso, J C; González-Correa, C H; González-Correa, C A

    2012-01-01

    BIA is a safe, noninvasive, portable and relatively inexpensive method of estimating body composition that is practical and suitable for individual use and large-scale studies. However, the cost of the electrodes recommended by some BIA manufacturers is too high for developing countries; where very often the long and complicated process of importation reduces the time they can be used. The purpose of this study was to evaluate the use of two types of ECG electrodes (2290 and 2228 by 3M ® ) in BIA measurements to decrease the costs of the test. The results showed that the 2228 ECG electrodes can be used in BIA measurements for adult's body composition assessment. These electrodes are available in the domestic market and their costs are 92% lower than the electrodes recommended by manufacturer. The results show a new cost-benefit relation for BIA method and make this a more accessible tool for individual tests, large-scale researches and studies in the community.

  6. Cross validation of bioelectrical impedance equations for men

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    Maria Fátima Glaner

    2005-06-01

    Full Text Available The purpose of this study was to analyze the cross validity of bioimpedance equations (BIA on the estimation of the fat free mass (FFM of 44 men, with mean age of 24.98 ± 3.40 years and relative body fat (%BF of 17.15 ± 6.41%. A dual energy x-ray absorptiometry was used as a reference method for %BF and FFM. Total body resistance was assessed by the Biodynamics (Model 310. The equations analyzed in this study were: two equations (Eq.1 and 2 developed by Carvalho e Pires Neto (1998; one equation (Eq. 3 developed by Rising et al.(1991; one equation (Eq. 4 developed by Oppliger et al.(1991; two equations (Eq. 5 (%FM RESUMO Este estudo teve como objetivo analisar a validade concorrente de equações de impedância bioelétrica (IB para estimar a massa corporal livre de gordura (MLG, em 44 homens, com idade média de 24,98 ± 3,40 anos e gordura relativa (%G de 17,15 ± 6,41 %. A absortometria de raio-x de dupla energia foi usada como critério, para mensurar a %G e a MLG, e para obter estas variáveis decorrentes das equações de IB foi utilizado o Biodynamics (Modelo 310. As equações de IB analisadas neste estudo foram: duas equações (Eq. 1 e 2 de Carvalho e Pires Neto (1998; uma equação (Eq. 3 de Rising et al. (1991; uma equação (Eq. 4 de Oppliger et al.(1991; duas equações (Eq. 5 (%G < 20% e Eq. 6 (%G ≥ 20% de Segal et al. (1988. Os critérios adotados para validação foram os propostos por Lohman (1991. Todas as correlações foram altas e significativas, oscilando de 0,906 (Eq. 2 a 0,981 (Eq. 6. As equações 1 a 5 superestimaram de forma significativa (p < 0,001 a MLG, sendo que os erros constantes variaram de 1,32 kg (Eq. 5 a 5,90 kg (Eq. 4. A equação 6 atendeu a todos os critérios de validação, apresentando: correlação = 0,981; erro constante = -0,38 kg; erro total = 1,10 kg. Esta equação de Segal et al.(1988, para homens com gordura relativa ≥ 20% (Eq. 6 foi a única que apresentou validade concorrente, estimando

  7. The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer

    Directory of Open Access Journals (Sweden)

    Grutsch James F

    2008-06-01

    Full Text Available Abstract Background Bioelectrical Impedance (BIA derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as either well-nourished or malnourished using the SGA. BIA was conducted on all patients and phase angle was calculated. The correlation between phase angle and SGA was studied using Spearman correlation coefficient. Receiver Operating Characteristic curves were estimated using the non-parametric method to determine the optimal cut-off levels of phase angle. Results Well-nourished patients had a statistically significantly higher (p = 0.005 median phase angle score (6.12 as compared to those who were malnourished (5.18. The Spearman rank correlation coefficient between phase angle and SGA was found to be 0.33 (p = 0.004, suggesting better nutritional status with higher phase angle scores. A phase angle cut-off of 5.2 was 51.7% sensitive and 79.5% specific whereas a cut-off of 6.0 was 82.8% sensitive and 54.5% specific in detecting malnutrition. Interestingly, a phase angle cut-off of 5.9 demonstrated high diagnostic accuracy in males who had failed primary treatment for advanced colorectal cancer. Conclusion Our study suggests that bioimpedance phase angle is a potential nutritional indicator in advanced colorectal cancer. Further research is needed to elucidate the optimal cut-off levels of phase angle that can be incorporated into the oncology clinic for better nutritional evaluation and management.

  8. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities.

    Science.gov (United States)

    Havinga-Top, A M; Waninge, A; van der Schans, C P; Jager-Wittenaar, H

    2015-12-01

    Body composition measurements provide important information about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a reliable and non-invasive method to asses body composition in healthy persons and various patient populations; however, currently, there is no feasible method available to determine body composition in people with SIVD. In this study, therefore, we aimed to assess the feasibility of BIA measurements in persons with SIVD. In 33 participants with SIVD and Gross Motor Functioning Classification System (GMFCS) Scale I, II, III, or IV, two BIA measurements were sequentially performed employing Resistance and Reactance in Ohm and fat-free mass (FFM) in kg as outcome variables, utilizing the Bodystat(®) QuadScan 4000. Feasibility was considered sufficient if ≥ 80% of the first measurement was performed successfully. Agreement between two repeated measurements was determined by using the paired t-test and Intraclass Correlation Coefficient (ICC; two way random, absolute agreement). Bland-Altman analyses were utilized to determine limits of agreement (LOAs) and systematic error. Agreement was considered acceptable if LOAs were feasible in persons with SIVD. Although these results require confirmation in a more extensive sample of persons with SIVD, the findings of this study are an important first step in the assessment of applicability of BIA measurements for non-invasive monitoring of physical fitness and nutritional status of persons with SIVD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Evaluation of Bioelectrical Impedance Spectroscopy for the Assessment of Extracellular Body Water

    Directory of Open Access Journals (Sweden)

    Sören Weyer

    2012-01-01

    Full Text Available This study evaluates bioelectrical impedance spectroscopy (BIS measurements to detect body fluid status. The multifrequency impedance measurements were performed in five female pigs. Animals were connected to an extracorporeal membrane oxygenation device during a lung disease experiment and fluid balance was recorded. Every 15 min the amount of fluid infusion and the weight of the urine drainage bag was recorded. From the fluid intake and output, the fluid balance was calculated. These data were compared with values calculated from a mathematical model, based on the extracellular tissue resistance and the Hanai Mixture theory. The extracellular tissue resistance was also measured with BIS. These experimental results strongly support the feasibility and clinical value of BIS for in vivo assessment of the hydration status.

  10. Validating Body Fat Assessment by Bioelectric Impedance Spectroscopy in Taiwanese Hemodialysis Patients.

    Science.gov (United States)

    Lim, Paik Seong; Chen, Chang Hsu; Zhu, Fansan; Kotanko, Peter; Jeng, Yachung; Hu, Chun Yu; Chiu, Li Shu; Chang, Hui-Chen

    2017-01-01

    Obesity is becoming increasingly common in hemodialysis (HD) patients and is associated with inflammation and increased mortality. The primary aim of the present study was to evaluate the accuracy and variability of the bioimpedance device in measuring body fat in Taiwanese dialysis patients. Cross-sectional study. One hundred twenty-two adult patients receiving HD in a single hospital in Taiwan. We compared the results of fat mass (FM) measured by dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance spectroscopy device (Body composition monitor, BCM). FM measured by BCM was calculated by subtracting fat-free mass (FFM) from body mass assuming fractional hydration of FFM of 0.73 or the proprietary prediction equations from the BCM model. Assessment of whole-body composition showed that percentage FM measured using the 2 techniques was highly correlated when using the BCM model or estimating from total body water using constant (0.73) hydration (r = 0.87, P < .001). There was no evident difference in measurement between patients gender. The Bland-Altman plot also showed good agreement of percentage of FM (t = 3.82; P < .001). In female patients, it was found that BCM significantly underestimated mean FM as compared to DEXA. However, the mean differences of the estimates between the methods were small (0.35 ± 3.00 kg) and with Bland-Altman plot the limits of agreements were -5.5 to 6.2 kg (P = .40) for FM in female patients. Using DEXA as the reference test, BCM is a valid tool for the assessment of total body fat in HD patients. Hence, it may provide a more accessible tool for early detection of changes in body composition in these high-risk patients. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  11. Prevalence of rheumatoid cachexia assessed by bioelectrical impedance vector analysis and its relation with physical function.

    Science.gov (United States)

    Santillán-Díaz, Cira; Ramírez-Sánchez, Noemi; Espinosa-Morales, Rolando; Orea-Tejeda, Arturo; Llorente, Luis; Rodríguez-Guevara, Gerardo; Castillo-Martínez, Lilia

    2018-03-01

    Rheumatoid arthritis (RA) patients frequently have changes in their body composition, with a decrease in muscle mass and an increase in fat mass, a syndrome that is termed rheumatoid cachexia (RC). The prevalence of this nutritional alteration is not well known; there is as yet no consensus, seeing as it depends on the methods, techniques, and cutoff points that are used for its diagnosis. The main aim of this study was to identify RC through assessment by bioelectrical impedance vector analysis (BIVA) and its association with metabolic causes, physical function, and the main disease status, among others. The prevalence of RC was identified in those subjects who fell outside the right lower quadrant of the reference curve of RXc graph of BIVA. Clinical, anthropometric, biochemical and physical activity, emotional status, and diet markers were also evaluated. Ninety-four patients were included (92.55% women). The prevalence of RC assessed by BIVA was 21.28%. BIVA-cachexia patients had a lesser value of handgrip strength vs. patients without BIVA-cachexia 10.2 kg (7.2-13.4) vs. 14.7 kg (9.6-19), p = 0.0062. Disability and folic acid with methotrexate consumption are related to BIVA-cachexia ((OR 4.69, 95% CI 1.33, 16.54, p = 0.016) and (OR 0.19, 95%CI 0.058, 0.651, p = 0.008), respectively). BIVA could represent a valuable tool to assess presence of RC. It is important that RA patients have physical therapy to improve their nutritional status.

  12. Measurement errors in multifrequency bioelectrical impedance analyzers with and without impedance electrode mismatch

    International Nuclear Information System (INIS)

    Bogónez-Franco, P; Nescolarde, L; Bragós, R; Rosell-Ferrer, J; Yandiola, I

    2009-01-01

    The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the patient to ground and the skin–electrode impedance mismatch. Results showed that both sets of equipment are optimized for right-side measurements and for moderate skin–electrode impedance mismatch. In right-side measurements with mismatch electrode, 4000B is more accurate than SFB7. When an electrode impedance mismatch was simulated, errors increased in both bioimpedance analyzers and the effect of the mismatch in the voltage detection leads was greater than that in current injection leads. For segments with lower impedance as the leg and thorax, SFB7 is more accurate than 4000B and also shows less dependence on electrode mismatch. In both devices, impedance measurements were not significantly affected (p > 0.05) by the capacitive coupling to ground

  13. Validity of bioelectrical impedance analysis to assess fat−free mass in head and neck cancer patients : an exploratory study

    NARCIS (Netherlands)

    Jager-Wittenaar, Harriët; Dijkstra, Pieter; Earthman, Carrie; Krijnen, Wim; Langendijk, Johannes A.; van der Laan, Bernard; Pruim, Jan; Roodenburg, Jan

    2013-01-01

    Assessment and monitoring of fat-free mass (FFM) is of clinical importance, because FFM is reflective of body cell mass, the total mass of protein-rich, metabolically active cells which is affected during malnutrition and therefore related to clinical outcome. Bioelectrical impedance analysis (BIA)

  14. The relationship between nocturnal polyuria and the distribution of body fluid: assessment by bioelectric impedance analysis.

    Science.gov (United States)

    Torimoto, Kazumasa; Hirayama, Akihide; Samma, Shoji; Yoshida, Katsunori; Fujimoto, Kiyohide; Hirao, Yoshihiko

    2009-01-01

    Increased nocturnal urinary volume is closely associated with nocturia. We investigated the relationship between nocturnal polyuria and the variation of body fluid distribution during the daytime using bioelectric impedance analysis. A total of 34 men older than 60 years were enrolled in this study. A frequency volume chart was recorded. Nocturnal polyuria was defined as a nocturnal urine volume per 24-hour production of greater than 0.35 (the nocturnal polyuria index). Bioelectric impedance analysis was performed 4 times daily at 8 and 11 a.m., and 5 and 9 p.m. using an InBody S20 body composition analyzer (BioSpace, Seoul, Korea). A significant difference was found in mean +/- SEM 24-hour urine production per fat-free mass between the groups with and without nocturnal polyuria (17.8 +/- 1.4 vs 7.7 +/- 0.9 ml/kg). The increase in fluid in the legs compared with the volume at 8 a.m. was significantly larger at 5 p.m., while there was no difference in the arms or trunk. Nocturnal urine volume significantly correlated with the difference in fluid volume in the legs (r = 0.527, p = 0.0019) and extracellular fluid volume (r = 0.3844, p = 0.0248) between the volumes at 8 a.m. and 9 p.m. Overproduction of urine per fat-free mass leads to nocturnal polyuria. Extracellular fluid accumulates as edema in the legs during the day in patients with nocturnal polyuria. The volume of accumulated extracellular fluid correlates with nocturnal urine volume. We suggest that leg edema is the source of nocturnal urine volume and decreasing edema may cure nocturnal polyuria.

  15. Does bioelectrical impedance analysis accurately estimate the condition of threatened and endangered desert fish species?

    Science.gov (United States)

    Dibble, Kimberly L.; Yard, Micheal D.; Ward, David L.; Yackulic, Charles B.

    2017-01-01

    Bioelectrical impedance analysis (BIA) is a nonlethal tool with which to estimate the physiological condition of animals that has potential value in research on endangered species. However, the effectiveness of BIA varies by species, the methodology continues to be refined, and incidental mortality rates are unknown. Under laboratory conditions we tested the value of using BIA in addition to morphological measurements such as total length and wet mass to estimate proximate composition (lipid, protein, ash, water, dry mass, energy density) in the endangered Humpback Chub Gila cypha and Bonytail G. elegans and the species of concern Roundtail Chub G. robusta and conducted separate trials to estimate the mortality rates of these sensitive species. Although Humpback and Roundtail Chub exhibited no or low mortality in response to taking BIA measurements versus handling for length and wet-mass measurements, Bonytails exhibited 14% and 47% mortality in the BIA and handling experiments, respectively, indicating that survival following stress is species specific. Derived BIA measurements were included in the best models for most proximate components; however, the added value of BIA as a predictor was marginal except in the absence of accurate wet-mass data. Bioelectrical impedance analysis improved the R2 of the best percentage-based models by no more than 4% relative to models based on morphology. Simulated field conditions indicated that BIA models became increasingly better than morphometric models at estimating proximate composition as the observation error around wet-mass measurements increased. However, since the overall proportion of variance explained by percentage-based models was low and BIA was mostly a redundant predictor, we caution against the use of BIA in field applications for these sensitive fish species.

  16. Drug and bioactive molecule screening based on a bioelectrical impedance cell culture platform

    Directory of Open Access Journals (Sweden)

    Ramasamy S

    2014-12-01

    Full Text Available Sakthivel Ramasamy,1 Devasier Bennet,1 Sanghyo Kim1,2 1Department of Bionanotechnology, Gachon University, Gyeonggi-Do, Republic of Korea; 2Graduate Gachon Medical Research Institute, Gil Medical Center, Incheon, Republic of Korea Abstract: This review will present a brief discussion on the recent advancements of bioelectrical impedance cell-based biosensors, especially the electric cell-substrate impedance sensing (ECIS system for screening of various bioactive molecules. The different technical integrations of various chip types, working principles, measurement systems, and applications for drug targeting of molecules in cells are highlighted in this paper. Screening of bioactive molecules based on electric cell-substrate impedance sensing is a trial-and-error process toward the development of therapeutically active agents for drug discovery and therapeutics. In general, bioactive molecule screening can be used to identify active molecular targets for various diseases and toxicity at the cellular level with nanoscale resolution. In the innovation and screening of new drugs or bioactive molecules, the activeness, the efficacy of the compound, and safety in biological systems are the main concerns on which determination of drug candidates is based. Further, drug discovery and screening of compounds are often performed in cell-based test systems in order to reduce costs and save time. Moreover, this system can provide more relevant results in in vivo studies, as well as high-throughput drug screening for various diseases during the early stages of drug discovery. Recently, MEMS technologies and integration with image detection techniques have been employed successfully. These new technologies and their possible ongoing transformations are addressed. Select reports are outlined, and not all the work that has been performed in the field of drug screening and development is covered. Keywords: screening of bioactive agents, impedance-based cell

  17. Comparison of Body Fat Results from 4 Bioelectrical Impedance Analysis Devices vs. Air Displacement Plethysmography in American Adolescent Wrestlers

    Directory of Open Access Journals (Sweden)

    Melissa M. Montgomery

    2017-10-01

    Full Text Available Background: Accurate and accessible methods of body composition are necessary to ensure health and safety of wrestlers during competition. The most valid and reliable instruments are expensive and relatively inaccessible to high school wrestlers; therefore, more practical technology is needed. Objective: To compare body fat percentage (BF% results from 4 bioelectrical impedance analysis (BIA devices to those from air displacement plethysmography (ADP in adolescent wrestlers. Methodology: 134 adolescent male and female wrestlers (1.72±0.9 m, 66.8±14.3 kg, 15.6±1.1 yrs. were tested for hydration and then completed 4 body composition tests with different BIA devices and one with Bod Pod. Relative and absolute agreement were assessed between each BIA device and ADP on a single day. Results: When compared with ADP, all devices demonstrated excellent reliability (ICC (2,1 range: 0.88-0.94, but questionable measurement error (SEM range: 2.3-3.6 %BF. Bland-Altman plots revealed that each bioelectrical impedance device we tested over-estimated body fat percent in high school wrestlers (range: 0.8-3.6 %BF and demonstrated wide 95% limits of agreement (range: 15.0-20.8 %BF compared to ADP. Conclusions: The devices investigated demonstrated reasonable measurement accuracy. However, wide margins of error of each device were noted. Caution should be taken when assessing adolescent wrestlers with lower amounts of body fat, as it may result in failing to identify those who do not meet the minimum body fat percentage for competition. The governing bodies should use the research data in the decision-making process regarding appropriate devices for use in their weight management programs.

  18. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

    Directory of Open Access Journals (Sweden)

    Ahyoung Choi

    2015-09-01

    Full Text Available Current bioelectric impedance analysis (BIA systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea. In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC in South Korea and the Pennington Biomedical Research Center (PBRC in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p < 0.0001. Additionally, body fat estimates from DXA did not yield significant differences (p > 0.728 (paired t-test, DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg. Thus, this portable BIA system shows a promising ability to estimate an individual’s body composition that is comparable to large stationary BIA systems.

  19. Discordance between bioelectrical impedance vector analysis and the new ESPEN definition of malnutrition for the diagnosis of hospital malnutrition.

    Science.gov (United States)

    Dehesa-López, Edgar; Martínez-Felix, Jesús Israel; Ruiz-Ramos, Arturo; Atilano-Carsi, Ximena

    2017-04-01

    No universally accepted diagnostic criteria for malnutrition are available to date. The aim was to assess the concordance for the diagnosis of hospital malnutrition between the bioelectrical impedance vector analysis (BIVA) and the new definition of malnutrition proposed by the European Society for Clinical Nutrition and Metabolism (ESPEN). A total of 140 adult hospitalized patients were included. The malnutrition risk was assessed by the Nutritional Risk Screening. The ESPEN malnutrition criteria (body mass index (BMI) malnutrition was diagnosed using the BIVA method. Diagnostic concordance between the BIVA and the new ESPEN definition was assessed with the Kappa coefficient. The malnutrition prevalence was higher with the BIVA vs ESPEN definition (22.1% vs 13.6%) in the global population and was similar (12.8% vs 12.1%) in the population at risk of malnutrition. The diagnostic performance of the BIVA was acceptable, with higher sensitivity in patients with fluid overload (FO) and more specificity in euvolemic patients. Diagnostic concordance between the BIVA and the ESPEN definition was poor for the global population (kappa = 0.56) and the population at risk of malnutrition (kappa = 0.67) but was acceptable in patients with FO (kappa = 0.78). However, the discordant BIVA+/ESPEN- patients classified as false positives for BIVA showed clinical and body composition data (low FFMI, low phase angle) consistent with malnutrition. According to the clinical and bioelectrical characteristics of the discordant BIVA+/ESPEN- patients, the BIVA could perform better that the new ESPEN definition for the diagnosis of hospital malnutrition, which should be confirmed with other studies. Copyright © 2017 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

  20. Validity of a new abdominal bioelectrical impedance device to measure abdominal and visceral fat: comparison with MRI

    OpenAIRE

    Browning, Lucy M; Mugridge, Owen; Chatfield, Mark; Dixon, Adrian; Aitken, Sri; Joubert, Ilse; Prentice, Andrew M.; Jebb, Susan A

    2010-01-01

    Abdominal fat, and in particular, visceral adipose tissue (VAT), is the critical fat depot associated with metabolic aberrations. At present VAT can only be accurately measured by computed tomography (CT) or magnetic resonance imaging (MRI). This study was designed to compare a new abdominal bioelectrical impedance device against total abdominal adipose tissue (TAAT) and VAT area measurements made from an abdominal MRI scan, and to assess it’s reliability and accuracy.

  1. The novel application of artificial neural network on bioelectrical impedance analysis to assess the body composition in elderly

    Science.gov (United States)

    2013-01-01

    Background This study aims to improve accuracy of Bioelectrical Impedance Analysis (BIA) prediction equations for estimating fat free mass (FFM) of the elderly by using non-linear Back Propagation Artificial Neural Network (BP-ANN) model and to compare the predictive accuracy with the linear regression model by using energy dual X-ray absorptiometry (DXA) as reference method. Methods A total of 88 Taiwanese elderly adults were recruited in this study as subjects. Linear regression equations and BP-ANN prediction equation were developed using impedances and other anthropometrics for predicting the reference FFM measured by DXA (FFMDXA) in 36 male and 26 female Taiwanese elderly adults. The FFM estimated by BIA prediction equations using traditional linear regression model (FFMLR) and BP-ANN model (FFMANN) were compared to the FFMDXA. The measuring results of an additional 26 elderly adults were used to validate than accuracy of the predictive models. Results The results showed the significant predictors were impedance, gender, age, height and weight in developed FFMLR linear model (LR) for predicting FFM (coefficient of determination, r2 = 0.940; standard error of estimate (SEE) = 2.729 kg; root mean square error (RMSE) = 2.571kg, P < 0.001). The above predictors were set as the variables of the input layer by using five neurons in the BP-ANN model (r2 = 0.987 with a SD = 1.192 kg and relatively lower RMSE = 1.183 kg), which had greater (improved) accuracy for estimating FFM when compared with linear model. The results showed a better agreement existed between FFMANN and FFMDXA than that between FFMLR and FFMDXA. Conclusion When compared the performance of developed prediction equations for estimating reference FFMDXA, the linear model has lower r2 with a larger SD in predictive results than that of BP-ANN model, which indicated ANN model is more suitable for estimating FFM. PMID:23388042

  2. V-dotO2max prediction from multi-frequency bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Stahn, Alexander; Strobel, Günther; Terblanche, Elmarie

    2008-01-01

    Bioelectrical impedance analysis (BIA) has been shown to be highly related to skeletal muscle mass and blood volume, both of which are important determinants of maximal oxygen uptake (V-dotO 2max ). The aim of the present study was therefore to investigate the ability of whole-body and segmental multi-frequency BIA to improve current nonexercise V-dotO 2max prediction models. Data for V-dotO 2max (mL min −1 ), anthropometry, self-reported physical activity (PA-R) and BIA were collected in 115 men and women. Multiple linear regression analysis (MLR) was used to develop the most parsimonious prediction model. Segmental BIA was not superior to whole-body measurements. Correlation coefficients between V-dotO 2max and resistance indices were significantly higher at 500 kHz compared to 50 kHz (p 2max (r = 0.89). After adjusting for age, gender and PA-R, MLR revealed that the inclusion of intracellular resistance index was slightly, but significantly (p 2max ( −1 ). In short, whole-body BIA marginally improves the accuracy of nonexercise V-dotO 2max prediction models and its advantage is most pronounced in individuals with particularly low V-dotO 2max

  3. Alterations in body fluid content can be detected by bioelectrical impedance analysis.

    Science.gov (United States)

    Scheltinga, M R; Jacobs, D O; Kimbrough, T D; Wilmore, D W

    1991-05-01

    The electrical resistance across the whole body and its segments to the conduction of a weak alternating current was determined in human subjects under three different conditions: (1) during bed rest, (2) during infusion of 1 liter of saline, and (3) during donation of 1 unit of blood. During bed rest, extracellular and total body water were measured by dilution of bromide and heavy water, respectively. Electrical resistance obtained from electrodes placed on proximal portions of extremities ("proximal resistance") accounted for less than 50% of that determined by electrodes positioned on routinely used portions of a hand and foot ("whole body resistance"). Following saline infusion, resistance determined from the whole body and all its segments fell (P less than 0.001); the magnitude of the drop in both proximal and whole body resistance was inversely related to the volume of total body water (TBW) (r = -0.82, P less than 0.002, and r = -0.73, P less than 0.01, respectively). In contrast, blood donation was associated with significantly increased resistance at both measurement sites. TBW predicted from anthropometrics was inversely related to both proximal (r = -0.90, P less than 0.001) and whole body resistance (r = -0.75, P less than 0.001). Bioelectrical impedance analysis is a simple technique which may be useful in monitoring minimal alterations in TBW. Furthermore, altered fluid status may be predicted more accurately by changes in proximal resistance compared to changes in traditionally used whole body resistance.

  4. Validity of bioelectrical impedance analysis in estimation of fat-free mass in colorectal cancer patients.

    Science.gov (United States)

    Ræder, Hanna; Kværner, Ane Sørlie; Henriksen, Christine; Florholmen, Geir; Henriksen, Hege Berg; Bøhn, Siv Kjølsrud; Paur, Ingvild; Smeland, Sigbjørn; Blomhoff, Rune

    2018-02-01

    Bioelectrical impedance analysis (BIA) is an accessible and cheap method to measure fat-free mass (FFM). However, BIA estimates are subject to uncertainty in patient populations with altered body composition and hydration. The aim of the current study was to validate a whole-body and a segmental BIA device against dual-energy X-ray absorptiometry (DXA) in colorectal cancer (CRC) patients, and to investigate the ability of different empiric equations for BIA to predict DXA FFM (FFM DXA ). Forty-three non-metastatic CRC patients (aged 50-80 years) were enrolled in this study. Whole-body and segmental BIA FFM estimates (FFM whole-bodyBIA , FFM segmentalBIA ) were calculated using 14 empiric equations, including the equations from the manufacturers, before comparison to FFM DXA estimates. Strong linear relationships were observed between FFM BIA and FFM DXA estimates for all equations (R 2  = 0.94-0.98 for both devices). However, there were large discrepancies in FFM estimates depending on the equations used with mean differences in the ranges -6.5-6.8 kg and -11.0-3.4 kg for whole-body and segmental BIA, respectively. For whole-body BIA, 77% of BIA derived FFM estimates were significantly different from FFM DXA , whereas for segmental BIA, 85% were significantly different. For whole-body BIA, the Schols* equation gave the highest agreement with FFM DXA with mean difference ±SD of -0.16 ± 1.94 kg (p = 0.582). The manufacturer's equation gave a small overestimation of FFM with 1.46 ± 2.16 kg (p FFM DXA (0.17 ± 1.83 kg (p = 0.546)). Using the manufacturer's equation, no difference in FFM estimates was observed (-0.34 ± 2.06 kg (p = 0.292)), however, a clear proportional bias was detected (r = 0.69, p FFM compared to DXA using the optimal equation. In a population of non-metastatic CRC patients, mostly consisting of Caucasian adults and with a wide range of body composition measures, both the whole-body BIA and segmental BIA device

  5. Combined evaluation of nutrition and hydration in dialysis patients with bioelectrical impedance vector analysis (BIVA).

    Science.gov (United States)

    Piccoli, Antonio; Codognotto, Marta; Piasentin, Paola; Naso, Agostino

    2014-08-01

    Body hydration changes continuously in hemodialysis patients. The Subjective Global Assessment (SGA) is used for the nutritional evaluation but it does not allow a direct evaluation of hydration. Bioelectrical impedance vector analysis (BIVA) is very sensitive to hydration. The potential of the combined evaluation of hydration and nutrition with SGA and BIVA is still lacking. Observational cross-sectional study on 130 (94 Male) uremic patients undergoing chronic hemodialysis three times a week. Nutritional status was evaluated with the SGA. Each subject was classified as SGA-A (normal nutritional status), SGA-B (moderate malnutrition), or SGA-C (severe malnutrition). Body hydration was evaluated with BIVA. The two vector components resistance (R) and reactance (Xc) were normalized by the subject's height and standardized as bivariate Z-score, i.e. Z(R) and Z(Xc). Undernutrition influenced impedance vector distribution both before and after a dialysis session. In pre-dialysis, the mean vector of SGA A was inside the 50% tolerance ellipse. In SGA B and C, Z(R) was increased and Z(Xc) decreased, indicating a progressive loss of soft tissue mass. Fluid removal with dialysis increased both Z(R) and Z(Xc) in SGA A and B but not in C. With ROC curve analysis on the slope of increase, we found the cutoff value of 27.8° below which undernutrition was present, either moderate or severe. The area under the ROC curve was 77.7° (95% CI 69.5-84.5, P hydration in each SGA category can be detected with BIVA. Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  6. Validity of bioelectrical impedance measurement in predicting fat-free mass of Chinese children and adolescents.

    Science.gov (United States)

    Wang, Lin; Hui, Stanley Sai-chuen; Wong, Stephen Heung-sang

    2014-11-15

    The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents. A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz between the hand and the foot. The criterion measure of FFM was also employed using dual-energy X-ray absorptiometry (DEXA). FFM estimated from 24 published BIA equations was cross-validated against the criterion measure from DEXA. Multiple linear regression was conducted to examine alternative BIA equation for the studied population. FFM estimated from the 24 published BIA equations yielded high correlations with the directly measured FFM from DEXA. However, none of the 24 equations was statistically equivalent with the DEXA-measured FFM. Using multiple linear regression and cross-validation against DEXA measurement, an alternative prediction equation was determined as follows: FFM (kg)=1.613+0.742×height (cm)2/impedance (Ω)+0.151×body weight (kg); R2=0.95; SEE=2.45 kg; CV=6.5, 93.7% of the residuals of all the participants fell within the 95% limits of agreement. BIA was highly correlated with FFM in Chinese children and adolescents. When the new developed BIA equations are applied, BIA can provide a practical and valid measurement of body composition in Chinese children and adolescents.

  7. Development of bioelectrical impedance analysis-based equations for estimation of body composition in postpartum rural Bangladeshi women.

    Science.gov (United States)

    Shaikh, Saijuddin; Schulze, Kerry J; Kurpad, Anura; Ali, Hasmot; Shamim, Abu Ahmed; Mehra, Sucheta; Wu, Lee S-F; Rashid, Mahbubar; Labrique, Alain B; Christian, Parul; West, Keith P

    2013-02-28

    Equations for predicting body composition from bioelectrical impedance analysis (BIA) parameters are age-, sex- and population-specific. Currently there are no equations applicable to women of reproductive age in rural South Asia. Hence, we developed equations for estimating total body water (TBW), fat-free mass (FFM) and fat mass in rural Bangladeshi women using BIA, with ²H₂O dilution as the criterion method. Women of reproductive age, participating in a community-based placebo-controlled trial of vitamin A or β-carotene supplementation, were enrolled at 19·7 (SD 9·3) weeks postpartum in a study to measure body composition by ²H₂O dilution and impedance at 50 kHz using multi-frequency BIA (n 147), and resistance at 50 kHz using single-frequency BIA (n 82). TBW (kg) by ²H2O dilution was used to derive prediction equations for body composition from BIA measures. The prediction equation was applied to resistance measures obtained at 13 weeks postpartum in a larger population of postpartum women (n 1020). TBW, FFM and fat were 22·6 (SD 2·7), 30·9 (SD 3·7) and 10·2 (SD 3·8) kg by ²H₂O dilution. Height²/impedance or height²/resistance and weight provided the best estimate of TBW, with adjusted R² 0·78 and 0·76, and with paired absolute differences in TBW of 0·02 (SD 1·33) and 0·00 (SD 1·28) kg, respectively, between BIA and ²H₂O. In the larger sample, values for TBW, FFM and fat were 23·8, 32·5 and 10·3 kg, respectively. BIA can be an important tool for assessing body composition in women of reproductive age in rural South Asia where poor maternal nutrition is common.

  8. Reference Centile Curves for Body Fat Percentage, Fat-free Mass, Muscle Mass and Bone Mass Measured by Bioelectrical Impedance in Asian Indian Children and Adolescents.

    Science.gov (United States)

    Chiplonkar, Shashi; Kajale, Neha; Ekbote, Veena; Mandlik, Rubina; Parthasarathy, Lavanya; Borade, Ashwin; Patel, Pinal; Patel, Prerna; Khadilkar, Vaman; Khadilkar, Anuradha

    2017-12-15

    To create gender-specific percentile curves for percent body fat (%BF) by Bio electrical Impedance Analysis (BIA) for screening adiposity and risk of hypertension in Indian children and generate reference curves for percent fat-free mass (%FFM), muscle mass (%LM) and bone mineral content (BMC) by using bioelectrical impedance. Secondary analysis of data from previous multicenter cross-sectional studies. Private schools from five regions of India. A random sample of 3850 healthy school children (2067 boys) (5-17 yr) from private schools in five major Indian cities. Anthropometry, blood pressure (BP) and body composition were measured by bioelectrical impedance. Reference curves were generated by the LMS method. %BF, %FFM, %LM, BMC and BP. Median %BF increased by 6% from 5 to 13 years of age and declined (around 2%) up to 17 years in boys. In girls, %BF increased by 8% from 5 to 14 years and thereafter declined by 3%. Based upon the risk of hypertension, the new cut-offs of 75th and 85th percentile of %BF were proposed for detecting over fatness and excess fatness in children. Median %FFM was 90% at 5 yrs and decreased till 12 years, and then showed a slight increase to 84% at 17 yrs in boys. In girls, it was 86% at 5 yrs and decreased till 15 yrs, and plateaued at 71.8% at 17 yrs. Reference curves for percent body fat for Indian children would be useful to screen children for health risk in clinical set up.

  9. Estimation of prevalence of sarcopenia by using a new bioelectrical impedance analysis in Chinese community-dwelling elderly people.

    Science.gov (United States)

    Wang, Hui; Hai, Shan; Cao, Li; Zhou, Jianghua; Liu, Ping; Dong, Bi-Rong

    2016-12-28

    The aim of the present study was to validate the usefulness of the new octapolar multifrequency bioelectrical impedance analysis (BIA) for assessment of appendicular skeletal muscle mass (ASM) by comparing it with that of dual-energy X-ray absorptiometry (DXA) and to investigate the prevalence of sarcopenia in Chinese community-dwelling elderly according to Asian Working Group for Sarcopenia (AWGS) definition. A cross-sectional study was conducted in communities of Chengdu, China. A total of 944 community-dwelling elderly adults aged ≥60 years were included. ASM was measured by using DXA as a criterion method to validate a standing eight-electrode multifrequency BIA (InBody 720), followed by a further estimation of the prevalence of sarcopenia according the AWGS definition. In the Bland-Altman analysis, no significant difference was found between DXA and BIA based on the ASM measurements. The prevalence of AWGS-defined sarcopenia was 12.5% in the elderly women and 8.2% in the elderly men. BIA is suitable for body composition monitoring (ASM) in elderly Chinese as a fast, noninvasive, and convenient method; therefore, it may be a better choice in large epidemiological studies in the Chinese population. The prevalence of AWGS-defined sarcopenia was approximately 10.4% and increased with age in the Chinese community-dwelling elderly in this study.

  10. Relationship between Height-Weight Difference Index and Body-Fat Percentage Estimated by Bioelectrical Impedance Analysis in Thai Adults

    Directory of Open Access Journals (Sweden)

    Kanokkarn Juntaping

    2017-01-01

    Full Text Available Introduction. The height-weight difference index (HWDI is a new indicator for evaluating obesity status. While body-fat percentage (BF% is considered to be the most accurate obesity evaluation tool, it is a more expensive method and more difficult to measure than the others. Objective. Our objectives were to find the relationship between HWDI and BF% and to find a BF% prediction model from HWDI in relation to age and gender. Method. Bioelectrical impedance analysis was used to measure BF% in 2,771 healthy adult Thais. HWDI was calculated as the difference between height and weight. Pearson’s correlation coefficient was used to assess the relationship between HWDI and BF%. Multiple linear and nonlinear regression analysis were used to construct the BF% prediction model. Results. HWDI and BF% were found to be inverse which related to a tendency toward a linear relationship. Results of a multivariate linear regression analysis, which included HWDI and age as variables in the model, predicted BF% to be 34.508 − 0.159 (HWDI + 0.161 (age for men and 53.35 − 0.265 (HWDI + 0.132 (age for women. Conclusions. The prediction model provides an easy-to-use obesity evaluation tool that should help awareness of underweight and obesity conditions.

  11. Association of phase angle on bioelectrical impedance analysis and dialysis frequency with survival of chronic hemodialysis patients

    Science.gov (United States)

    Muzasti, R. A.; Lubis, H. R.

    2018-03-01

    Phase angle, a parameter by Bioelectrical Impedance Analysis, can detect body composition changes, so it can be used as a prognostic indicator in some chronic conditions. This study was for determining the relationship between PhA and hemodiálisis frequency with the survival of chronic hemodiálisis patients. This longitudinal retrospective study involved 173 chronic hemodiálisis patients at Rasyida Renal Hospital. The Kaplan-Meier method is used to determine the survival. Cox proportional hazard analysis is used to determine which variables significantly increase mortality. During the study period, 89 patients underwent hemodiálysis 3x a week (4 hours/session), and 84 patients underwent HD 2x a week (5 hours/session). Demographic and clinical characteristics in both groups were similar. There was no difference in PhA value in groups of 3x a week and group 2x a week (4.02 ± 1.13 vs 4.25 ± 1.12). Patients with twice a week hemodiálisis had a shorter survival than the 3x week group (35.14 ± 2.76 vs 38.62 ± 3.03) although it was not statistically significant (p = 0.126).

  12. Increased abdominal fat levels measured by bioelectrical impedance are associated with histological lesions of nonalcoholic steatohepatitis.

    Science.gov (United States)

    Margariti, Aikaterini; Kontogianni, Meropi D; Tileli, Nafsika; Georgoulis, Michael; Deutsch, Melanie; Zafeiropoulou, Rodessa; Tiniakos, Dina; Manios, Yannis; Pectasides, Dimitrios; Papatheodoridis, George V

    2015-08-01

    Abdominal fat is considered to play an important role in nonalcoholic fatty liver disease (NAFLD), although it is not adequately studied because abdominal fat levels cannot be estimated easily. In this study, associations between abdominal obesity, as assessed by abdominal bioelectrical impedance analysis (BIA), and the characteristics of patients with NAFLD were explored. Seventy-four consecutive NAFLD patients who underwent measurement of abdominal fat levels by BIA were included. Levels of abdominal fat 12.5 or less and more than 12.5 were considered to be average and increased, respectively. The mean±SD BMI was 30±4 kg/m and the mean abdominal fat levels were 16±5, whereas 26% of patients had average abdominal fat levels. Patients with average compared with those with increased abdominal fat levels were more frequently women (50 vs. 12%, P=0.001), had lower BMI (27±3 vs. 31±4 kg/m, Pabdominal fat levels (78 vs. 38%, P=0.030) and in patients with BMI 30 or more compared with less than 30 kg/m (87 vs. 48%, P=0.033), but similar in patients with increased or normal waist circumference (67 vs. 56%, P=0.693). Average levels of abdominal fat, as assessed by abdominal BIA, are mainly present in female patients with NAFLD and are associated with a lower degree of insulin resistance. Increased abdominal fat as assessed by BIA and obesity seem to represent strong risk factors for histological steatohepatitis.

  13. The validity and accuracy in foot-to-foot bioelectrical impedance ...

    African Journals Online (AJOL)

    owner

    2011-04-18

    Apr 18, 2011 ... impedance analysis measuring models referenced by dual-energy ... The ZF-F value was 481.85 ± 63.37 ohm in male and ... BIA method to predict the body composition such as ... position have been published, the comparison of various ..... Bioimpedance analysis: evaluation of leg-to-leg system based.

  14. Making the invisible visible: bioelectrical impedance analysis demonstrates unfavourable body composition in rheumatoid arthritis patients in clinical practice.

    Science.gov (United States)

    Konijn, N P C; van Tuyl, L H D; Bultink, I E M; Lems, W F; Earthman, C P; van Bokhorst-de van der Schueren, M A E

    2014-01-01

    To examine differences between the assessment of body composition by body mass index (BMI) and bioelectrical impedance analysis (BIA) in patients with rheumatoid arthritis (RA). The body composition of RA patients was assessed during their visit to the outpatient department of a Dutch academic hospital using BMI, fat-free mass index (FFMI), and fat mass index (FMI). FFMI and FMI were determined by single-frequency BIA. Sixty-five consecutive RA patients (83% women, mean age 58 years, median disease duration 7 years) with moderately active disease [mean Disease Activity Score using 28 joint counts (DAS28) = 3.40; mean Rheumatoid Arthritis Disease Activity Index (RADAI) score = 3.49] and moderate disability [mean Health Assessment Questionnaire (HAQ) score = 0.87] were included. Based on BMI, 2% of our study population were underweight, 45% had a healthy body composition, and 54% were overweight or obese. Based on BIA, 18% of the patients showed a low FFMI and 74% had a high or very high FMI. Low FFMI was found in 44% of the women with a normal BMI, and high FMI was found in 40% of the women and 75% of the men with a normal BMI. A high frequency of unfavourable body composition, predominantly reduced FFMI and elevated FMI, was found in a cohort of RA patients with moderately active disease, turning BMI into an unreliable method for assessment of body composition in RA. BIA, however, might be the preferred method to assess FFMI and FMI in RA patients in clinical practice, as it is easy to use and relatively inexpensive.

  15. Validation of equations using anthropometric and bioelectrical impedance for estimating body composition of the elderly

    Directory of Open Access Journals (Sweden)

    Cassiano Ricardo Rech

    2006-08-01

    Full Text Available The increase of the elderly population has enhanced the need for studying aging-related issues. In this context, the analysis of morphological alterations occurring with the age has been discussed thoroughly. Evidences point that there are few information on valid methods for estimating body composition of senior citizens in Brazil. Therefore, the objective of this study was to cross-validate equations using either anthropometric or bioelectrical impedance (BIA data for estimation of body fat (%BF and of fat-free mass (FFM in a sample of older individuals from Florianópolis-SC, having the dual energy x-ray absorptiometry (DEXA as the criterion-measurement. The group was composed by 180 subjects (60 men and 120 women who participated in four community Groups for the elderly and were systematically randomly selected by a telephone interview, with age ranging from 60 to 81 years. The variables stature, body mass, body circumferences, skinfold thickness, reactance and resistance were measured in the morning at The Sports Center of the Federal University of Santa Catarina. The DEXA evaluation was performed in the afternoon at The Diagnosis Center through Image in Florianópolis-SC. Twenty anthropometric and 8 BIA equations were analyzed for cross-validation. For those equations that estimate body density, the equation of Siri (1961 and the adapted-equation by Deurenberg et al. (1989 were used for conversion into %BF. The analyses were performed with the statistical package SPSS, version 11.5, establishing the level of significance at 5%. The criteria of cross-validation suggested by Lohman (1992 and the graphic dispersion analyses in relation to the mean, as proposed by Bland and Altman (1986 were used. The group presented values for the body mass index (BMI between 18.4kg.m-2 and 39.3kg.m-2. The mean %BF was of 23.1% (sd=5.8 for men and 37.3% (sd=6.9 in women, varying from 6% to 51.4%. There were no differences among the estimates of the equations

  16. Prevalence of malnutrition and validation of bioelectrical impedance analysis for the assessment of body composition in patients with systemic sclerosis.

    Science.gov (United States)

    Spanjer, Moon J; Bultink, Irene E M; de van der Schueren, Marian A E; Voskuyl, Alexandre E

    2017-06-01

    The aims were to assess the prevalence of malnutrition and to validate bioelectrical impedance analysis (BIA) against whole-body DXA for the assessment of body composition in patients with SSc. Malnutrition was defined as BMI 10% in combination with a fat-free mass index (FFMI) 70 years). Body composition was assessed in 72 patients with whole-body DXA (Hologic, Discovery A) and BIA (Bodystat Quadscan 400). The manufacturer's equation and the Geneva equation were used to estimate FFM and fat mass. The agreement between BIA and whole-body DXA was assessed with Bland-Altman analysis and intraclass correlation coefficient. Malnutrition was found in 8.3% (n = 6) and low FFMI in 20.8% (n = 15) of patients. The mean difference in FFM between BIA and DXA applying the Geneva equation was 0.02 ( s . d . 2.4) kg, intraclass correlation coefficient 0.97 (95% CI: 0.95, 0.98). Limits of agreement were ±4.6 kg. The manufacturer's equation was less adequate to predict FFM. This study shows a relatively low prevalence of malnutrition in comparison with other studies, but a high prevalence of low FFMI, underlining the necessity of measuring body composition in SSc patients with a standardized and validated method. A good validity of BIA in determining FFM was found at a group level, while at an individual level the FFM may vary by 4.6 kg. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  17. Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: is ethnic-specific calibration of bioelectrical impedance required?

    Directory of Open Access Journals (Sweden)

    Simon Lee

    Full Text Available Bioelectrical Impedance Analysis (BIA has the potential to be used widely as a method of assessing body fatness and composition, both in clinical and community settings. BIA provides bioelectrical properties, such as whole-body impedance which ideally needs to be calibrated against a gold-standard method in order to provide accurate estimates of fat-free mass. UK studies in older children and adolescents have shown that, when used in multi-ethnic populations, calibration equations need to include ethnic-specific terms, but whether this holds true for younger children remains to be elucidated. The aims of this study were to examine ethnic differences in body size, proportions and composition in children aged 5 to 11 years, and to establish the extent to which such differences could influence BIA calibration.In a multi-ethnic population of 2171 London primary school-children (47% boys; 34% White, 29% Black African/Caribbean, 25% South Asian, 12% Other detailed anthropometric measurements were performed and ethnic differences in body size and proportion were assessed. Ethnic differences in fat-free mass, derived by deuterium dilution, were further evaluated in a subsample of the population (n = 698. Multiple linear regression models were used to calibrate BIA against deuterium dilution.In children < 11 years of age, Black African/Caribbean children were significantly taller, heavier and had larger body size than children of other ethnicities. They also had larger waist and limb girths and relatively longer legs. Despite these differences, ethnic-specific terms did not contribute significantly to the BIA calibration equation (Fat-free mass = 1.12+0.71*(height2/impedance+0.18*weight.Although clear ethnic differences in body size, proportions and composition were evident in this population of young children aged 5 to 11 years, an ethnic-specific BIA calibration equation was not required.

  18. Validity of segmental bioelectrical impedance analysis for estimating fat-free mass in children including overweight individuals.

    Science.gov (United States)

    Ohta, Megumi; Midorikawa, Taishi; Hikihara, Yuki; Masuo, Yoshihisa; Sakamoto, Shizuo; Torii, Suguru; Kawakami, Yasuo; Fukunaga, Tetsuo; Kanehisa, Hiroaki

    2017-02-01

    This study examined the validity of segmental bioelectrical impedance (BI) analysis for predicting the fat-free masses (FFMs) of whole-body and body segments in children including overweight individuals. The FFM and impedance (Z) values of arms, trunk, legs, and whole body were determined using a dual-energy X-ray absorptiometry and segmental BI analyses, respectively, in 149 boys and girls aged 6 to 12 years, who were divided into model-development (n = 74), cross-validation (n = 35), and overweight (n = 40) groups. Simple regression analysis was applied to (length) 2 /Z (BI index) for each of the whole-body and 3 segments to develop the prediction equations of the measured FFM of the related body part. In the model-development group, the BI index of each of the 3 segments and whole body was significantly correlated to the measured FFM (R 2 = 0.867-0.932, standard error of estimation = 0.18-1.44 kg (5.9%-8.7%)). There was no significant difference between the measured and predicted FFM values without systematic error. The application of each equation derived in the model-development group to the cross-validation and overweight groups did not produce significant differences between the measured and predicted FFM values and systematic errors, with an exception that the arm FFM in the overweight group was overestimated. Segmental bioelectrical impedance analysis is useful for predicting the FFM of each of whole-body and body segments in children including overweight individuals, although the application for estimating arm FFM in overweight individuals requires a certain modification.

  19. Preoperative and postoperative agreement in fat free mass (FFM) between bioelectrical impedance spectroscopy (BIS) and dual-energy X-ray absorptiometry (DXA) in patients undergoing cardiac surgery

    NARCIS (Netherlands)

    van Venrooij, Lenny M. W.; Verberne, Hein J.; de Vos, Rien; Borgmeijer-Hoelen, Mieke M. M. J.; van Leeuwen, Paul A. M.; de Mol, Bas A. J. M.

    2010-01-01

    Background & aims: To measure undernutrition in terms of fat free mass (FFM), there are several options. The aim of this study was to assess agreement in FFM between the portable, bedside bioelectrical impedance spectrometry (BIS) and relatively expensive, non-portable dual-energy X-ray

  20. Prediction of fat-free body mass from bioelectrical impedance among 9- to 11-year-old Swedish children

    DEFF Research Database (Denmark)

    Nielsen, Birgit Marie; Dencker, M; Ward, L

    2007-01-01

    AIM: Predictive equations for estimating body composition from bioelectrical impedance analysis (BIA) among Scandinavian children are lacking. In the present study, equations for estimation of fat-free body mass (FFM) and lean tissue mass (LTM) were developed and cross-validated from BIA using dual...... linear regression and cross-validated against DXA measurements of body composition. RESULTS: FFM was predicted from BIA and anthropometric variables with an adjusted R(2)= 0.95 and root mean square error (RMSE) = 0.84 kg, and LTM was predicted with an adjusted R(2)= 0.95 and RMSE = 0.87 kg. Cross......-validation revealed a mean RMSE = 0.95 kg FFM and a mean RMSE = 0.96 kg LTM. Prediction of body composition from equations developed in previous literature was mixed when applied to the present cohort of children. CONCLUSIONS: FFM and LTM are predicted with sufficient accuracy at the population level. We recommend...

  1. Accuracy of Bioelectrical Impedance Analysis in Estimated Longitudinal Fat-Free Mass Changes in Male Army Cadets.

    Science.gov (United States)

    Langer, Raquel D; Matias, Catarina N; Borges, Juliano H; Cirolini, Vagner X; Páscoa, Mauro A; Guerra-Júnior, Gil; Gonçalves, Ezequiel M

    2018-03-26

    Bioelectrical impedance analysis (BIA) is a practical and rapid method for making a longitudinal analysis of changes in body composition. However, most BIA validation studies have been performed in a clinical population and only at one moment, or point in time (cross-sectional study). The aim of this study is to investigate the accuracy of predictive equations based on BIA with regard to the changes in fat-free mass (FFM) in Brazilian male army cadets after 7 mo of military training. The values used were determined using dual-energy X-ray absorptiometry (DXA) as a reference method. The study included 310 male Brazilian Army cadets (aged 17-24 yr). FFM was measured using eight general predictive BIA equations, with one equation specifically applied to this population sample, and the values were compared with results obtained using DXA. The student's t-test, adjusted coefficient of determination (R2), standard error of estimation (SEE), Lin's approach, and the Bland-Altman test were used to determine the accuracy of the predictive BIA equations used to estimate FFM in this population and between the two moments (pre- and post-moment). The FFM measured using the nine predictive BIA equations, and determined using DXA at the post-moment, showed a significant increase when compared with the pre-moment (p FFM changes in the army cadets between the two moments in a very similar way to the reference method (DXA). However, only the one BIA equation specific to this population showed no significant differences in the FFM estimation between DXA at pre- and post-moment of military routine. All predictive BIA equations showed large limits of agreement using the Bland-Altman approach. The eight general predictive BIA equations used in this study were not found to be valid for analyzing the FFM changes in the Brazilian male army cadets, after a period of approximately 7 mo of military training. Although the BIA equation specific to this population is dependent on the amount of

  2. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    Science.gov (United States)

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs. Copyright © 2016. Published by Elsevier Ltd.

  3. Assessment of fat-free mass from bioelectrical impedance analysis in obese women with Prader-Willi syndrome.

    Science.gov (United States)

    Bedogni, Giorgio; Grugni, Graziano; Tringali, Gabriella; Agosti, Fiorenza; Sartorio, Alessandro

    2015-01-01

    Fat-free mass (FFM) is lower in obese subjects with Prader-Willi syndrome (PWS) than in obese subjects without PWS. FFM prediction equations developed in non-PWS subjects may, thus, not work in PWS subjects. To test whether the estimation of FFM from bioelectrical impedance analysis (BIA) in PWS subjects requires population-specific equations. Using dual-energy X-ray absorptiometry, this study measured FFM in 27 PWS and 56 non-PWS obese women and evaluated its association with the impedance index at 50 kHz (ZI50), i.e. the ratio between squared height and whole-body impedance at 50 kHz. At the same level of ZI50, PWS women had a lower FFM than non-PWS women. However, when PWS-specific equations were used, FFM was accurately estimated at the population level. An equation employing a dummy variable coding for PWS status was able to explain 85% of the variance of FFM with a root mean squared error of 3.3 kg in the pooled sample (n = 83). Population-specific equations are needed to estimate FFM from BIA in obese PWS women.

  4. The use of bioelectrical impedance analysis to estimate total body water in young children with cerebral palsy.

    Science.gov (United States)

    Bell, Kristie L; Boyd, Roslyn N; Walker, Jacqueline L; Stevenson, Richard D; Davies, Peter S W

    2013-08-01

    Body composition assessment is an essential component of nutritional evaluation in children with cerebral palsy. This study aimed to validate bioelectrical impedance to estimate total body water in young children with cerebral palsy and determine best electrode placement in unilateral impairment. 55 young children with cerebral palsy across all functional ability levels were included. Height/length was measured or estimated from knee height. Total body water was estimated using a Bodystat 1500MDD and three equations, and measured using the gold standard, deuterium dilution technique. Comparisons were made using Bland Altman analysis. For children with bilateral impairment, the Fjeld equation estimated total body water with the least bias (limits of agreement): 0.0 L (-1.4 L to 1.5 L); the Pencharz equation produced the greatest: 2.7 L (0.6 L-4.8 L). For children with unilateral impairment, differences between measured and estimated total body water were lowest on the unimpaired side using the Fjeld equation 0.1 L (-1.5 L to 1.6 L)) and greatest for the Pencharz equation. The ability of bioelectrical impedance to estimate total body water depends on the equation chosen. The Fjeld equation was the most accurate for the group, however, individual results varied by up to 18%. A population specific equation was developed and may enhance the accuracy of estimates. Australian New Zealand Clinical Trials Registry (ANZCTR) number: ACTRN12611000616976. Copyright © 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  5. Validation of two portable bioelectrical impedance analyses for the assessment of body composition in school age children.

    Directory of Open Access Journals (Sweden)

    Li-Wen Lee

    Full Text Available Bioelectrical impedance analysis (BIA is a convenient and child-friendly method for longitudinal analysis of changes in body composition. However, most validation studies of BIA have been performed on adult Caucasians. The present cross-sectional study investigated the validity of two portable BIA devices, the Inbody 230 (BIA8MF and the Tanita BC-418 (BIA8SF, in healthy Taiwanese children.Children aged 7-12 years (72 boys and 78 girls were recruited. Body composition was measured by the BIA8SF and the BIA8MF. Dual X-ray absorptiometry (DXA was used as the reference method.There were strong linear correlations in body composition measurements between the BIA8SF and DXA and between the BIA8MF and DXA. Both BIAs underestimated fat mass (FM and percentage body fat (%BF relative to DXA in both genders The degree of agreement in lean body mass (LBM, FM, and %BF estimates was higher between BIA8MF and DXA than between BIA8SF and DXA. The Lin's concordance correlation coefficient (ρc for LBM8MF met the criteria of substantial to perfect agreement whereas the ρc for FM8MF met the criteria of fair to substantial agreement. Bland-Altman analysis showed a clinically acceptable agreement between LBM measures by BIA8MF and DXA. The limit of agreement in %BF estimation by BIA and DXA were wide and the errors were clinically important. For the estimation of ALM, BIA8SF and BIA8MF both provided poor accuracy.For all children, LBM measures were precise and accurate using the BIA8MF whereas clinically significant errors occurred in FM and %BF estimates. Both BIAs underestimated FM and %BF in children. Thus, the body composition results obtained using the inbuilt equations of the BIA8SF and BIA8MF should be interpreted with caution, and high quality validation studies for specific subgroups of children are required prior to field research.

  6. New reference values for body composition by bioelectrical impedance analysis in the general population: results from the UK Biobank.

    Science.gov (United States)

    Franssen, Frits M E; Rutten, Erica P A; Groenen, Miriam T J; Vanfleteren, Lowie E; Wouters, Emiel F M; Spruit, Martijn A

    2014-06-01

    Low fat-free mass (FFM) is a risk factor for morbidity and mortality in elderly and patient populations. Therefore, measurement of FFM is important in nutritional assessment. Bioelectrical impedance analysis (BIA) is a convenient method to assess FFM and FFM index (FFMI; FFM/height(2)). Although reference values have been established for individuals with normal body weight, no specific cutoff values are available for overweight and obese populations. Also, limited studies accounted for the age-related decline in FFM. To determine BMI- and age-specific reference values for abnormal low FFM(I) in white-ethnic men and women free of self-reported disease from the general population. The UK Biobank is a prospective epidemiological study of the general population from the United Kingdom. Individuals in the age category 45 to 69 years were analyzed. In addition to body weight, FFM and FFMI were measured using a Tanita BC-418MA. Also, self-reported chronic conditions and ethnic background were registered, and lung function was assessed using spirometry. After exclusion of all individuals with missing data, nonwhite ethnicity, self-reported disease, body mass index (BMI) less than 14 or 36 kg/m(2) or higher, and/or an obstructive lung function, reference values for FFM and FFMI were derived from 186,975 individuals (45.9% men; age: 56.9 ± 6.8 years; BMI: 26.5 ± 3.6 kg/m(2); FFMI 18.3 ± 2.4 kg/m(2)). FFM and FFMI were significantly associated with BMI and decreased with age. Percentiles 5, 10, 25, 50, 75, 90, and 95 were calculated for FFM, FFMI, and fat mass (index), after stratification for gender, age, and BMI. Using the UK Biobank dataset, new reference values for body composition assessed with BIA were determined in white-ethnic men and women aged 45 to 69 years. Because these reference values are BMI specific, they are of broad interest for overweight and obese populations. Copyright © 2014 American Medical Directors Association, Inc. Published by Elsevier Inc. All

  7. Preliminary bioelectrical impedance analysis (BIA) equation for body composition assessment in young females from Colombia

    International Nuclear Information System (INIS)

    Caicedo, J C; González-Correa, C H; González-Correa, C A

    2013-01-01

    A previous study showed that reported BIA equations for body composition are not suitable for Colombian population. The purpose of this study was to develop and validate a preliminary BIA equation for body composition assessment in young females from Colombia, using hydrodensitometry as reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, BIA, residual lung volume (RV) and underwater weight (UWW) were measured. A preliminary BIA equation was developed (r 2 = 0.72, SEE = 2.48 kg) by stepwise multiple regression with fat-free mass (FFM) as dependent variable and weight, height and impedance measurements as independent variables. The quality of regression was evaluated and a cross-validation against 50% of sample confirmed that results obtained with the preliminary BIA equation is interchangeable with results obtained with hydrodensitometry (r 2 = 0.84, SEE = 2.62 kg). The preliminary BIA equation can be used for body composition assessment in young females from Colombia until a definitive equation is developed. The next step will be increasing the sample, including a second reference method, as deuterium oxide dilution (D 2 O), and using multi-frequency BIA (MF-BIA). It would also be desirable to develop equations for males and other ethnic groups in Colombia.

  8. Influence of Posture and Frequency Modes in Total Body Water Estimation Using Bioelectrical Impedance Spectroscopy in Boys and Adult Males

    Directory of Open Access Journals (Sweden)

    Masaharu Kagawa

    2014-05-01

    Full Text Available The aim of the study was to examine differences in total body water (TBW measured using single-frequency (SF and multi-frequency (MF modes of bioelectrical impedance spectroscopy (BIS in children and adults measured in different postures using the deuterium (2H dilution technique as the reference. Twenty-three boys and 26 adult males underwent assessment of TBW using the dilution technique and BIS measured in supine and standing positions using two frequencies of the SF mode (50 kHz and 100 kHz and the MF mode. While TBW estimated from the MF mode was comparable, extra-cellular fluid (ECF and intra-cellular fluid (ICF values differed significantly (p < 0.01 between the different postures in both groups. In addition, while estimated TBW in adult males using the MF mode was significantly (p < 0.01 greater than the result from the dilution technique, TBW estimated using the SF mode and prediction equation was significantly (p < 0.01 lower in boys. Measurement posture may not affect estimation of TBW in boys and adult males, however, body fluid shifts may still occur. In addition, technical factors, including selection of prediction equation, may be important when TBW is estimated from measured impedance.

  9. Effect of the ethinylestradiol/norelgestromin contraceptive patch on body composition. Results of bioelectrical impedance analysis in a population of Italian women

    Directory of Open Access Journals (Sweden)

    Bruni Vincenzina

    2008-08-01

    Full Text Available Abstract Background As weight gain is one of the most frequently cited reasons for not using and for discontinuing hormonal contraceptives, in an open-label, single-arm, multicentre clinical study we evaluated the effect of the ethinylestradiol/norelgestromin contraceptive patch (EVRA, Janssen-Cilag International, Belgium on body composition using bioelectrical impedance analysis (BIA. Methods Body weight and impedance vector components (resistance (R and reactance (Xc, at 50 kHz frequency, Akern-RJL Systems analyzer were recorded before entry, after 1, 3 and 6 months in 182 Italian healthy women aged 29 yr (18 to 45, and with BMI 21.8 kg/m2 (16 to 31. Total body water (TBW was estimated with a BIA regression equation. Vector BIA was performed with the RXc mean graph method and the Hotelling's T2 test for paired and unpaired data. Results After 6 months body weight increased by 0.64 kg (1.1% and TBW increased by 0.51 L (1.7%. The pattern of impedance vector displacement indicated a small increase in soft tissue hydration (interstitial gel fluid. Body composition changes did not significantly differ among groups of previous contraceptive methods. Arterial blood pressure did not significantly change over time. Conclusion After 6 months of treatment with the ethinylestradiol/norelgestromin contraceptive patch we found a minimal, clinically not relevant, increase in body weight less than 1 kg that could be attributed to an adaptive interstitial gel hydration. This fluctuation is physiological as confirmed by the lack of any effect on blood pressure. This could be useful in increasing women's choice, acceptability and compliance of the ethinylestradiol/norelgestromin contraceptive patch.

  10. Nutrition Status Parameters and Hydration Status by Bioelectrical Impedance Vector Analysis Were Associated With Lung Function Impairment in Children and Adolescents With Cystic Fibrosis.

    Science.gov (United States)

    Hauschild, Daniela Barbieri; Barbosa, Eliana; Moreira, Emilia Addison Machado; Ludwig Neto, Norberto; Platt, Vanessa Borges; Piacentini Filho, Eduardo; Wazlawik, Elisabeth; Moreno, Yara Maria Franco

    2016-06-01

    (1) To compare nutrition and hydration status between a group of children/adolescents with cystic fibrosis (CFG; n = 46; median age, 8.5 years) and a control group without cystic fibrosis (CG). (2) To examine the association of nutrition and hydration status with lung function in the CFG. A cross-sectional study. Nutrition screening, anthropometric parameters, and bioelectrical impedance analysis (BIA) were assessed. The z scores for body mass index for age, height for age, mid upper arm circumference, triceps and subscapular skinfold thickness, mid upper arm muscle area, resistance/height, and reactance/height were calculated. Bioelectrical impedance vector analysis was conducted. Forced expiratory volume in 1 second hydration status were associated with lung function. © 2016 American Society for Parenteral and Enteral Nutrition.

  11. Body composition of adult cystic fibrosis patients and control subjects as determined by densitometry, bioelectrical impedance, total-body electrical conductivity, skinfold measurements, and deuterium oxide dilution

    International Nuclear Information System (INIS)

    Newby, M.J.; Keim, N.L.; Brown, D.L.

    1990-01-01

    This study contrasts body compositions (by six methods) of eight cystic fibrosis (CF) subjects with those of eight control subjects matched for age, height, and sex. CF subjects weighed 84% as much as control subjects. Densitometry and two bioelectrical impedance-analysis methods suggested that reduced CF weights were due to less lean tissue (10.7, 9.5, and 10.4 kg). Total-body electrical conductivity (TOBEC) and skinfold-thickness measurements indicated that CF subjects were leaner than control subjects and had less fat (5.4 and 3.6 kg) and less lean (5.2 and 7 kg) tissue. D2O dilution showed a pattern similar to TOBEC (8.3 kg less lean, 2.7 kg less fat tissue). Densitometry estimates of fat (mass and percent) were not correlated (r less than 0.74, p greater than 0.05) with any other method for CF subjects but were correlated with all other methods for control subjects. CF subjects contained less fat and lean tissue than did control subjects. Densitometry by underwater weighing is unsuitable for assessing body composition of CF patients

  12. Bioelectrical impedance spectroscopy as a fluid management system in heart failure

    International Nuclear Information System (INIS)

    Weyer, Sören; Wartzek, Tobias; Leicht, Lennart; Leonhardt, Steffen; Zink, Matthias Daniel; Mischke, Karl; Vollmer, Thomas

    2014-01-01

    Episodes of hospitalization for heart failure patients are frequent and are often accompanied by fluid accumulations. The change of the body impedance, measured by bioimpendace spectroscopy, is an indicator of the water content. The hypothesis was that it is possible to detect edema from the impedance data. First, a finite integration technique was applied to test the feasibility and allowed a theoretical analysis of current flows through the body. Based on the results of the simulations, a clinical study was designed and conducted. The segmental impedances of 25 patients suffering from heart failure were monitored over their recompensation process. The mean age of the patients was 73.8 and their mean body mass index was 28.6. From these raw data the model parameters from the Cole model were deduced by an automatic fitting algorithm. These model data were used to classify the edema status of the patient. The baseline values of the regression lines of the extra- and intracellular resistance from the transthoracic measurement and the baseline value of the regression line of the extracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of peripheral edema. The rate of change of the imaginary impedance at the characteristic frequency and the mean intracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of pulmonary edema. To classify the data, two decision trees were considered: One should detect pulmonary edema (n pulmonary = 13, n none = 12) and the other peripheral edema (n peripheral = 12, n none = 13). Peripheral edema could be detected with a sensitivity of 100% and a specificity of 90%. The detection of pulmonary edema showed a sensitivity of 92.31% and a specificity of 100%. The leave-one-out cross-validation-error for the peripheral edema detection was 12% and 8% for the detection of pulmonary edema. This enables the application of BIS as an

  13. Validity of Standing Posture Eight-electrode Bioelectrical Impedance to Estimate Body Composition in Taiwanese Elderly

    Directory of Open Access Journals (Sweden)

    Ling-Chun Lee

    2014-09-01

    Conclusion: The results of this study showed that the impedance index and LST in the whole body, upper limbs, and lower limbs derived from DXA findings were highly correlated. The LST and BF% estimated by BIA8 in whole body and various body segments were highly correlated with the corresponding DXA results; however, BC-418 overestimates the participants' appendicular LST and underestimates whole body BF%. Therefore, caution is needed when interpreting the results of appendicular LST and whole body BF% estimated for elderly adults.

  14. Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Altamir, Vaz; Frère, Slaets Annie France; Leonardo, López Ramírez

    2012-01-01

    Body-fat is essential for human body, provided that its amount is at healthy levels. If in-excess body-fat is deleterious, its lack is otherwise also harmful. Estimated percent body-fat performed with commercially available devices measuring bioimpedance have many advantages, such as easy measurement and low cost. However, these measurements are based on standard models and equations that are not disclosed by manufacturers, and this leads to questioning the validity of these estimates for Brazilian females. The aim of this study was to compare electrical tetrapolar and octapolar impedance results obtained with commercially available equipment: Maltron BF-906 and OMRON 510-W. Data analysis involved descriptive and inferential statistics. Devices used in this study to estimate body fat quantity have not shown any significant differences in results; this is a major issue when selecting equipment based on three factors: study focus, available financial resources, and target population. Results obtained from the two devices have not shown any significant differences, which lead to the conclusion that either device may be reliably used.

  15. The investigation of the some body parameters of obese and (obese+diabetes) patients with using bioelectrical impedance analysis techniques

    Science.gov (United States)

    Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep

    2016-04-01

    Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount p<0.00 between (diabetes+obese) and obese groups. Besides, when these patient groups and control group were analyzed, there were significant difference between most parameters. In terms of education level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result

  16. Novel use of bioelectric impedence technique to detect alterations in body composition in advanced small cell lung cancer.

    Science.gov (United States)

    Mohan, A; Poulose, R; Ansari, A; Madan, K; Hadda, V; Khilnani, G C; Guleria, R

    2017-01-01

    Malnutrition is frequent in lung cancer and is measured using various tools, including the novel bioelectric impedance technique for measuring body composition. However, the validation of this technique for assessing body composition in advanced small cell lung cancer (SCLC) is untested. Forty-one treatment naïve patients (all males) and an equal number of age- and sex-matched controls were evaluated by anthropometric measurements of skinfold thicknesses and body composition parameters such as body fat%, fat mass, fat-free mass (FFM), and total body water (TBW). The mean (SD) age of the patient group was 55.7 (7.5) years, median pack-years was 20 (range, 0-80), and mean (SD) duration of symptoms was 152.6 (153.7) days. Median Karnofsky Performance Scale was 70 (range, 50-90). Majority of our patients (68.3%) were Stage IV followed by Stage III (31.7%). The percentage of patients with low, normal, and high body mass index (BMI) was 31.7%, 61%, and 7.3%, respectively. All components of body composition, i.e., body fat%, FFM, and TBW were significantly lower in patients compared to controls. However, the body composition in patients and controls with normal BMI was similar. The phenomenon of sarcopenia as a cause of cancer cachexia may explain these findings, whereas the combination of loss of body fat and lean body mass may lead to weight loss and reduced BMI. Our results indicate that body composition is markedly altered in Indian patients with advanced SCLC. The impact of these parameters on clinically relevant outcomes needs further evaluation.

  17. Fat mass to fat-free mass ratio reference values from NHANES III using bioelectrical impedance analysis.

    Science.gov (United States)

    Xiao, J; Purcell, S A; Prado, C M; Gonzalez, M C

    2017-10-06

    Low fat-free mass (FFM) or high fat mass (FM) are abnormal body composition phenotypes associated with morbidity. These conditions in combination lead to worse health outcomes, and can be identified by a high FM/FFM ratio. Here, we developed sex, age, and body mass index (BMI) stratified, population-based FM/FFM reference values using bioelectrical impedance analysis (BIA) measurements. White, non-Hispanic individuals aged 18-90 years old with data for weight, stature and BIA resistance measures from the third National Health and Nutrition Examination Survey (NHANES) III were included. Previously validated and sex-specific BIA prediction equations were used to calculate FM and FFM. FM/FFM values were generated at 5th, 50th and 95th percentiles for each sex, age (18-39.9, 40-59.9, 60-69.9 and 70-90 years), and BMI category (underweight, normal weight, overweight, class I/II and class III obesity). A total of 6372 individuals who had estimated FM and FFM values were identified (3366 females, 3006 males). Median values of FM/FFM were 0.24 and 0.40 for young (≤39.9 years) males and females with normal BMI, and 0.34 for males and 0.59 for females who were overweight. For elderly individuals aged >70 years, median FM/FFM for males and females were respectively 0.28 and 0.45 for those with normal BMI, and 0.37 and 0.61 for those in the overweight category. These FM/FFM reference values provide information on body composition characteristics that account for age, sex and BMI, which can be useful to identify individuals at risk for body composition abnormalities. Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  18. Phase angle assessment by bioelectrical impedance analysis and its predictive value for malnutrition risk in hospitalized geriatric patients.

    Science.gov (United States)

    Varan, Hacer Dogan; Bolayir, Basak; Kara, Ozgur; Arik, Gunes; Kizilarslanoglu, Muhammet Cemal; Kilic, Mustafa Kemal; Sumer, Fatih; Kuyumcu, Mehmet Emin; Yesil, Yusuf; Yavuz, Burcu Balam; Halil, Meltem; Cankurtaran, Mustafa

    2016-12-01

    Phase angle (PhA) value determined by bioelectrical impedance analysis (BIA) is an indicator of cell membrane damage and body cell mass. Recent studies have shown that low PhA value is associated with increased nutritional risk in various group of patients. However, there have been only a few studies performed globally assessing the relationship between nutritional risk and PhA in hospitalized geriatric patients. The aim of the study is to evaluate the predictive value of the PhA for malnutrition risk in hospitalized geriatric patients. One hundred and twenty-two hospitalized geriatric patients were included in this cross-sectional study. Comprehensive geriatric assessment tests and BIA measurements were performed within the first 48 h after admission. Nutritional risk state of the patients was determined with NRS-2002. Phase angle values of the patients with malnutrition risk were compared with the patients that did not have the same risk. The independent variables for predicting malnutrition risk were determined. SPSS version 15 was utilized for the statistical analyzes. The patients with malnutrition risk had significantly lower phase angle values than the patients without malnutrition risk (p = 0.003). ROC curve analysis suggested that the optimum PhA cut-off point for malnutrition risk was 4.7° with 79.6 % sensitivity, 64.6 % specificity, 73.9 % positive predictive value, and 73.9 % negative predictive value. BMI, prealbumin, PhA, and Mini Mental State Examination Test scores were the independent variables for predicting malnutrition risk. PhA can be a useful, independent indicator for predicting malnutrition risk in hospitalized geriatric patients.

  19. [Comparison BMC assessed by dual-energy X-ray absorptiometry and multi-frequency bioelectrical impedance in Chinese overweight and obesity adults].

    Science.gov (United States)

    Wang, Zhenghe; Fu, Lianguo; Yang, Yide; Wang, Shuo; Ma, Jun

    2016-05-01

    To compare consistency of Body Mineral Content (BMC, kg) assessed by Multi-frequency Bioelectrical Impedance Analysis ( MF-BIA) and Dual Energy X-ray Absorptiometry (DXA) measurement, providing evidence for MF-BIA accurate application in Chinese overweight/obese adults. A total of 1323 overweight/obesity adults aged 22-55 years were recruited voluntarily. All the subjects received the measurement of BMC both using MF-BIA and DXA. To evaluate the agreement of BMC measured by MF-BIA and DXA using interclass correlation coefficients (ICC), then establish correction prediction models. The mean difference of BMC between two methods was significant different with 0, overweight male subgroup was 0.28 kg, and 0.38 kg for obesity male, 0.24 kg for overweight female and 0.36 kg for obesity female, respectively (P BMC between MF-BIA and DXA measurement were statistically significant in all subgroups (P BMC (DXA method) = -0.297 + 1.005 x BMC (MF-BIA method). Obese male population: BMC (DXA method) =0.302 + 0.799 x BMC (MF-BIA method). Overweight female groups: BMC (DXA method) = 0.780 + 0.598 x BMC (MF-BIA method). Obese female group: BMC (DXA method) = 0.755 + 0.597 x BMC (MF-BIA method). Upon examination, correction prediction models were better. Co The correlation and agreement of BMC measured by BIA and DXA are weak in Chinese overweight/obese adults. Therefore, consideration should be given to BMC measured by BIA method in Chinese overweight/obese adults. It should be corrected or adjusted to reduce errors compared with DXA method.

  20. Feasibility and acceptability of a self-measurement using a portable bioelectrical impedance analysis, by the patient with chronic heart failure, in acute decompensated heart failure.

    Science.gov (United States)

    Huguel, Benjamin; Vaugrenard, Thibaud; Saby, Ludivine; Benhamou, Lionel; Arméro, Sébastien; Camilleri, Élise; Langar, Aida; Alitta, Quentin; Grino, Michel; Retornaz, Frédérique

    2018-06-01

    Chronic heart failure (CHF) is a major public health matter. Mainly affecting the elderly, it is responsible for a high rate of hospitalization due to the frequency of acute heart failure (ADHF). This represents a disabling pathology for the patient and very costly for the health care system. Our study is designed to assess a connected and portable bioelectrical impedance analysis (BIA) that could reduce these hospitalizations by preventing early ADHF. This prospective study included patients hospitalized in cardiology for ADHF. Patients achieved 3 self-measurements using the BIA during their hospitalization and answered a questionnaire evaluating the acceptability of this self-measurement. The results of these measures were compared with the clinical, biological and echocardiographic criteria of patients at the same time. Twenty-three patients were included, the self-measurement during the overall duration of the hospitalization was conducted autonomously by more than 80% of the patients. The acceptability (90%) for the use of the portable BIA was excellent. Some correlations were statistically significant, such as the total water difference to the weight difference (p=0.001). There were common trends between the variation of impedance analysis measures and other evaluation criteria. The feasibility and acceptability of a self-measurement of bioelectrical impedance analysis by the patient in AHF opens up major prospects in the management of monitoring patients in CHF. The interest of this tool is the prevention of ADHF leading to hospitalization or re-hospitalizations now requires to be presented by new studies.

  1. Use of bioelectrical impedance analysis to assess body composition in rural Gambian children

    NARCIS (Netherlands)

    Prins, M.; Hawkesworth, S.; Wright, A.; Fulford, A.J.C.; Jarjou, L.M.A.; Prentice, A.M.; Moore, S.E.

    2008-01-01

    Objective: To validate the Tanita BC-418MA Segmental Body Composition Analyser and four-site skinfold measurements for the prediction of total body water (TBW), percentage fat-free mass (% FFM) and percentage body fat (%BF) in a population of rural Gambian children. Subjects/Methods: One hundred and

  2. Bioelectrical impedance analysis (BIA) equations validation against hydrodensitometry in a Colombian population

    International Nuclear Information System (INIS)

    Caicedo-Eraso, J C; Gonzalez-Correa, C A; Gonzalez-Correa, C H

    2013-01-01

    Several studies have shown that the accuracy of BIA results depends of ethnicity, age, gender, hormonal and genetic variations and, so far, there are not specific equations for Colombian population. The purpose was to evaluate reported BIA equations to determine their usefulness in body composition assessment in young females from Colombia using hydrodensitometry as the reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, multi-frequency BIA, residual lung volume (RV) and underwater weight (UWW) were measured. Five BIA equations met the inclusion criteria of this study. Three equations overestimated and two equations underestimated body fat (BF). Paired Student t-test and Bland and Altman analysis (p<0.05) showed significant differences in four BIA equations. However, all standard error of estimate (SEE) to BF was greater than 2.7 kg. This study showed that the five selected BIA equations are not valid for estimation of body composition in young females from Colombia. It is recommended to develop BIA equations to improve BF fat assessment in our population.

  3. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly

    International Nuclear Information System (INIS)

    Eickemberg, Michaela; Roriz, Anna Karla Carneiro; Fontes, Gardenia Abreu Vieira; Sampaio, Lilian Ramos

    2013-01-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas ≥ 130 cm 2 were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  4. Pengembangan Bioelectrical Impedance Sebagai Control Commands Pengaturan Kecepatan Gerak Kursi Roda Dengan Metoda PID Controller

    Directory of Open Access Journals (Sweden)

    Juli Sardi

    2014-09-01

    Full Text Available In the present study, bioimpedance signals of human body was utilized to control speed of a wheelchair movement. A bioimpedance is electrically passive part contained the body tissues. The research is one of alternative solutions for patients with paralysis of the upper and lower limb. Firstly, design of system of the research consisted of bioimpedance measuring instruments and a mechanical design of the wheelchair. Bioimpedance measurement was performed by injecting a sinusoidal current source of 0.5 mArms with a frequency of 50 kHz to muscle tissue (shoulder to obtain the output voltage in the range of 0-5 Vdc. With impulse and manual thresholding methods, the voltage signal was classified into several controls command to adjust the speed and direction of the wheelchair control based on PID Controller. The experimental result of the research was realization of bioimpedance signal that used as a reference to control the direction and speed of the wheelchair with a success rate of 86.7 %. A wheelchair velocity was classified into three types of motion, namely slow, medium and fast. Slow speed has a rated speed of 30 Cm/s, medium speed value speed of 40 Cm/s and fast speed value of 50 Cm/s. The wheelchair can also turn to the left and the right in accordance with the wishes of wheelchair user beside to moving forward.

  5. Hand-to-Hand Model for Bioelectrical Impedance Analysis to Estimate Fat Free Mass in a Healthy Population.

    Science.gov (United States)

    Lu, Hsueh-Kuan; Chiang, Li-Ming; Chen, Yu-Yawn; Chuang, Chih-Lin; Chen, Kuen-Tsann; Dwyer, Gregory B; Hsu, Ying-Lin; Chen, Chun-Hao; Hsieh, Kuen-Chang

    2016-10-21

    This study aimed to establish a hand-to-hand (HH) model for bioelectrical impedance analysis (BIA) fat free mass (FFM) estimation by comparing with a standing position hand-to-foot (HF) BIA model and dual energy X-ray absorptiometry (DXA); we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women) participated. FFM (FFM DXA ) reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland-Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping) were conducted to compare tests of agreement with FFM DXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFM m HH = 0.537 h²/Z HH - 0.126 year + 0.217 weight + 18.235 ( r ² = 0.919, standard estimate of error (SEE) = 2.164 kg, n = 269). The mean validated correlation coefficients and limits of agreement (LOAs) of the Bland-Altman analysis of the calculated values for FFM m HH and FFM DXA were 0.958 and -4.369-4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFM m HF ) and FFM DXA were 0.958 and -4.356-4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFM F HH = 0.615 h²/Z HH - 0.144 year + 0.132 weight + 16.507 ( r ² = 0.870, SEE = 1.884 kg, n = 201); the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFM F HH and FFM DXA ) were 0.929 and -3.880-3.886 kg, respectively. The FFM HF and FFM DXA were 0.942 and -3.511-3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.

  6. Hand-to-Hand Model for Bioelectrical Impedance Analysis to Estimate Fat Free Mass in a Healthy Population

    Directory of Open Access Journals (Sweden)

    Hsueh-Kuan Lu

    2016-10-01

    Full Text Available This study aimed to establish a hand-to-hand (HH model for bioelectrical impedance analysis (BIA fat free mass (FFM estimation by comparing with a standing position hand-to-foot (HF BIA model and dual energy X-ray absorptiometry (DXA; we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women participated. FFM (FFMDXA reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland–Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping were conducted to compare tests of agreement with FFMDXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFMmHH = 0.537 h2/ZHH − 0.126 year + 0.217 weight + 18.235 (r2 = 0.919, standard estimate of error (SEE = 2.164 kg, n = 269. The mean validated correlation coefficients and limits of agreement (LOAs of the Bland–Altman analysis of the calculated values for FFMmHH and FFMDXA were 0.958 and −4.369–4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFMmHF and FFMDXA were 0.958 and −4.356–4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFMFHH = 0.615 h2/ZHH − 0.144 year + 0.132 weight + 16.507 (r2 = 0.870, SEE = 1.884 kg, n = 201; the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFMFHH and FFMDXA were 0.929 and −3.880–3.886 kg, respectively. The FFMHF and FFMDXA were 0.942 and −3.511–3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.

  7. Bioelectrical impedance phase angle in clinical practice: implications for prognosis in stage IIIB and IV non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Grutsch James F

    2009-01-01

    Full Text Available Abstract Background A frequent manifestation of advanced lung cancer is malnutrition, timely identification and treatment of which can lead to improved patient outcomes. Bioelectrical impedance analysis (BIA is an easy-to-use and non-invasive technique to evaluate changes in body composition and nutritional status. We investigated the prognostic role of BIA-derived phase angle in advanced non-small cell lung cancer (NSCLC. Methods A case series of 165 stages IIIB and IV NSCLC patients treated at our center. The Kaplan Meier method was used to calculate survival. Cox proportional hazard models were constructed to evaluate the prognostic effect of phase angle, independent of stage at diagnosis and prior treatment history. Results 93 were males and 72 females. 61 had stage IIIB disease at diagnosis while 104 had stage IV. The median phase angle was 5.3 degrees (range = 2.9 – 8. Patients with phase angle 5.3 had 12.4 months (95% CI: 10.5 to 18.7; n = 84; (p = 0.02. After adjusting for age, stage at diagnosis and prior treatment history we found that every one degree increase in phase angle was associated with a relative risk of 0.79 (95% CI: 0.64 to 0.97, P = 0.02. Conclusion We found BIA-derived phase angle to be an independent prognostic indicator in patients with stage IIIB and IV NSCLC. Nutritional interventions targeted at improving phase angle could potentially lead to an improved survival in patients with advanced NSCLC.

  8. Bioelectrical impedance vectorial analysis and nutritional status of older women according. 10.5007/1980-0037.2011v13n6p415

    Directory of Open Access Journals (Sweden)

    Sandra Maria Lima Ribeiro

    2011-11-01

    Full Text Available The objective of the present study was to compare and discuss the nutritional status of older women according to different categories of BMI. Additionally, the study was aimed at introducing the bioelectrical impedance vector analysis (BIVA as a tool to assess the nutritional status. Thirty-two women (60 years or older, physically independent, and with moderate level of physical activity were divided into three groups according toBMI classification: G1 (BMI28 Kg/ m2. The following variables were analyzed as indicators of nutritional status: body mass and height to calculate BMI, waist circumference (WC, hip circumference (HC, waisthipratio (WHR, bioelectrical impedance (BIVA, resting energy expenditure (REE, biochemical markers of nutritional status (glucose, total cholesterol, and fractions, IGF-1, and leptin. The groups were compared using ANOVA and the Hotelling’s T 2 test for vector analysis. The main findings based on vector displacement showed lower reactance and higher resistance in G1. G3 showed the highest values of CC and leptin, and also lower REE. Therefore, higher BMI suggested at the same time higher cell mass and higher risk of developing chronic diseases. In turn, lower BMI values suggested reduced fat-free body mass. These results confirm the search for specific classification of BMI for the elderly and suggest the BIVA as a viable alternative in physical and nutritional assessment.

  9. Assessment of body fat proportion by means of bioelectrical impedance in athletic boys aged 7 to 18 years with respect to specific types of instruments

    Directory of Open Access Journals (Sweden)

    Sigmund Martin

    2015-07-01

    Full Text Available BACKGROUND: Bioelectrical impedance (BIA seems an appropriate method for basic diagnostics of body composition in a practical environment. This is a non-time consuming non-invasive method that provides a high degree of response relevance. However, the values identifi ed by the BIA method are susceptible to a number of factors, which need to be taken into account during the investigation stage and interpretation of the results. One of the signifi cant factors infl uencing the outcomes of measurement is the instrument factor.OBJECTIVE: The objective of the present comparative survey was to analyse the proportions of body fat by means of the BIA hand-to-leg method and BIA leg-to-leg method in a sample of athletic individuals aged 7 to 18 years.METHODS: The survey included a total of 178 ice-hockey players aged 7 to 18 years. The proportion of body fat analysed by means of the BIA hand-to-leg method was measured by the Tanita BC-418 MA instrument. For the purposes of the BIA leg-to-leg method the Tanita BF-350 instrument was used (Tanita, Japan. Both instruments work at a frequency of 50 kHz.RESULTS: The percentage of body fat established by the BIA leg-to-leg method (M = 13.5%; SD = 4.8 indicated signifi cantly lower values of fat percentage than the values measured by the BIA hand-to-leg method (M = 17.1%; SD = 4.3. The overall diff erence represents an average value of 3.6% (standard mode; p < .001; d = 0.8. Regarding the monitored age categories the observed diff erences are in the range of 3.1–4.7% (p < .001; d = 0.7–1.2.CONCLUSION: The present study compares the proportions of body fat by means of the BIA leg-to-leg method and BIA hand-to-leg method in athletic boys aged 7 to 18 years. The results measured by the BIA leg-to-leg method signifi cantly undervalue the proportion of body fat in comparison with the BIA hand-to-leg method. The instrument factor and age factor represented signifi - cant variables infl uencing the results of the

  10. Utility of Volume Assessment Using Bioelectrical Impedance Analysis in Critically Ill Patients Receiving Continuous Renal Replacement Therapy: A Prospective Observational Study

    Directory of Open Access Journals (Sweden)

    Ki Hyun Park

    2017-08-01

    Full Text Available Background Fluid overload prior to continuous renal replacement therapy (CRRT is an important prognostic factor. Thus, precise evaluation of fluid status is necessary to treat such patients. In this study, we investigated whether fluid assessment using bioelectrical impedance analysis (BIA can predict outcomes in critically ill patients requiring CRRT. Methods A prospective observational study was performed in patients who were admitted to the intensive care unit and who required CRRT. BIA was conducted before CRRT; then, the ratio of extracellular water to total body water (ECW/TBW was derived to estimate volume status. Results A total of 31 patients treated with CRRT were included. There were 18 men (58.1%, and the median age was 67 years (interquartile range, 51 to 78 years. Fourteen patients (45.2% died within 28 days after CRRT initiation. Patients were divided into 16 with ECW/TBW ≥0.41 and 15 with ECW/TBW <0.41. Survival rate within 28 days was different between the two groups (P = 0.044. Cox regression analysis revealed a relationship between ECW/TBW ≥0.41 and 28-day mortality, but it was not statistically significant (hazard ratio, 3.0; 95% confidence interval, 0.9 to 9.8; P = 0.061. Lastly, the area under the curve of ECW/TBW for 28-day mortality was analyzed. The area under the curve of ECW/TBW was 0.73 (95% confidence interval, 0.54 to 0.92, and this was significant (P = 0.037. Conclusions Fluid status can be assessed using BIA in critically ill patients requiring CRRT, and BIA can predict mortality. Further large trials are needed to confirm the usefulness of BIA in critically ill patients.

  11. Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study.

    Science.gov (United States)

    Hofsteenge, Geesje H; Chinapaw, Mai J M; Weijs, Peter J M

    2015-10-15

    In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11-18 years) compared to FFM measured by dual-energy x-ray absorptiometry (FFM-DXA) and a new population specific FFM-BIA equation is developed. After an overnight fast, the subjects attended the outpatient clinic. After measuring height and weight, a full body scan by dual-energy x-ray absorptiometry (DXA) and a BIA measurement was performed. Thirteen predictive FFM-BIA equations based on weight, height, age, resistance, reactance and/or impedance were systematically selected and compared to FFM-DXA. Accuracy of FFM-BIA equations was evaluated by the percentage adolescents predicted within 5% of FFM-DXA measured, the mean percentage difference between predicted and measured values (bias) and the Root Mean Squared prediction Error (RMSE). Multiple linear regression was conducted to develop a new BIA equation. Validation was based on 103 adolescents (60% girls), age 14.5 (sd1.7) years, weight 94.1 (sd15.6) kg and FFM-DXA of 56.1 (sd9.8) kg. The percentage accurate estimations varied between equations from 0 to 68%; bias ranged from -29.3 to +36.3% and RMSE ranged from 2.8 to 12.4 kg. An alternative prediction equation was developed: FFM = 0.527 * H(cm)(2)/Imp + 0.306 * weight - 1.862 (R(2) = 0.92, SEE = 2.85 kg). Percentage accurate prediction was 76%. Compared to DXA, the Gray equation underestimated the FFM with 0.4 kg (55.7 ± 8.3), had an RMSE of 3.2 kg, 63% accurate prediction and the smallest bias of (-0.1%). When split by sex, the Gray equation had the narrowest range in accurate predictions, bias, and RMSE. For the assessment of FFM with BIA, the Gray-FFM equation appears to be the most accurate, but 63% is still not at an acceptable accuracy level for obese adolescents. The new equation appears to

  12. Multi-frequency bioelectrical impedance analysis (BIA) compared to magnetic resonance imaging (MRI) for estimation of fat-free mass in colorectal cancer patients treated with chemotherapy

    DEFF Research Database (Denmark)

    Palle, Stine Skov; Tang Møllehave, Line; Kadkhoda, Zahra Taheri

    2016-01-01

    during the course of their treatments. Objective: To examine relationships between single cross-sectional thighs magnetic resonance imaging (MRI), skeletal muscle mass (SM) as reference and multi-frequency bioelectrical impedance analysis (BIA) fat free mass (FFM) in patients with colorectal cancer...... undergoing chemotherapy. Design: In an observational, prospective study we examine the relationships between single cross-sectional thighs MRI (T1-weighted (1.5 T) SM compared to FFM BIA (8-electrodes multi-frequency Tanita MC780MA)) and FFM skin-fold thickness (ST) (4-points (Harpenden, Skinfold Caliper......)) and SM equation for non-obese persons from Lee et al. 2000 (L2000) (based on age, height, weight, sex and race). FFM and SM (kg) were calculated based on either area (MRI) or weight. Results: 18 CRC patients (10 males and 8 females) with mean (SD) age 67 yr (6) were measured at baseline, and 13 were...

  13. Agreement Between Bioelectrical Impedance and Dual-Energy X-Ray Absorptiometry to Track Changes in Fat-Free Mass After Resistance Training in Older Women.

    Science.gov (United States)

    Nascimento, Matheus A; Silva, Danilo R P; Ribeiro, Alex S; Pina, Fábio L C; Gerage, Aline M; Gobbo, Luís A; Mayhew, Jerry L; Cyrino, Edilson S

    2018-05-23

    Nascimento, MA, Silva, DRP, Ribeiro, AS, Pina, FLC, Gerage, AM, Gobbo, LA, Mayhew, JL, and Cyrino, ES. Agreement between bioelectrical impedance and dual-energy x-ray absorptiometry to track changes in fat-free mass after resistance training in older women. J Strength Cond Res XX(X): 000-000, 2018-The aim of our study was to compare the agreement between bioelectrical impedance (BIA) and dual-energy X-ray absorptiometry (DXA) to track changes on fat-free mass (FFM) after a resistance training (RT) program in older women. Forty-three older women (65.2 ± 4.6 years, 59.5 ± 9.2 kg, 156.4 ± 6.0 cm, 24.3 ± 3.3 kg·m) participated in a RT intervention (12 weeks, 8 exercises, 2 sets, 10-15 repetitions, 3 nonconsecutive days per week). Fat-free mass changes were determined by a single-frequency BIA device (EQ1), 6 BIA prediction equations for older women (EQ2, EQ3, EQ4, EQ5, EQ6, and EQ7), and DXA. At pretraining, 3 equations overpredicted, and 3 underpredicted DXA FFM (F = 244.63, p FFM (F = 176.25, p FFM (0.65 ± 0.82 kg; p FFM. Low correlations between FFM and equation change values suggest that single-frequency BIA-derived equations may not provide sufficient accuracy to track changes in FFM after 12 weeks of RT in older women.

  14. Calibration of bioelectrical impedance analysis for body composition assessment in Ethiopian infants using air-displacement plethysmography

    DEFF Research Database (Denmark)

    Christensen, Rasmus Wibæk; Kæstel, Pernille; Skov, R.

    2015-01-01

    and noninvasive method for assessing BC. However, very little research has been conducted in low- and middle-income populations, where efforts to prevent or treat malnutrition in early life are a public health priority. We aimed to develop equations for predicting fat-free mass (FFM) and fat mass (FM) based......, age and an impedance index (L(2)/Z50) were predictors. Prediction equations were developed using stepwise multiple linear regression and the accuracy was evaluated with a 10-fold cross-validation approach. RESULTS: A linear regression model based on body weight, age and sex predicted FFM, estimated...... model fit for predicting FFM compared with a model already comprising weight, sex and age. CONCLUSIONS: The derived equations predicted FFM with acceptable accuracy and may be used in future field surveys, epidemiological studies and clinical trials conducted in similar sub-Saharan African population...

  15. Fluid management in the intensive care unit: bioelectrical impedance vector analysis as a tool to assess hydration status and optimal fluid balance in critically ill patients.

    Science.gov (United States)

    Basso, Flavio; Berdin, Giovanna; Virzì, Grazia Maria; Mason, Giacomo; Piccinni, Pasquale; Day, Sonya; Cruz, Dinna N; Wjewodzka, Marzena; Giuliani, Anna; Brendolan, Alessandra; Ronco, Claudio

    2013-01-01

    Fluid balance disorders are a relevant risk factor for morbidity and mortality in critically ill patients. Volume assessment in the intensive care unit (ICU) is thus of great importance, but there are currently few methods to obtain an accurate and timely assessment of hydration status. Our aim was to evaluate the hydration status of ICU patients via bioelectric impedance vector analysis (BIVA) and to investigate the relationship between hydration and mortality. We evaluated 280 BIVA measurements of 64 patients performed daily in the 5 days following their ICU admission. The observation period ranged from a minimum of 72 h up to a maximum of 120 h. We observed the evolution of the hydration status during the ICU stay in this population, and analyzed the relationship between mean and maximum hydration reached and mortality--both in the ICU and at 60 days--using logistic regression. A state of overhydration was observed in the majority of patients (70%) on admission, which persisted during the ICU stay. Patients who required continuous renal replacement therapy (CRRT) were more likely to be overhydrated starting from the 2nd day of observation. Logistic regression showed a strong and significant correlation between mean/maximum hydration reached and mortality, both independently and correcting for severity of prognosis. Fluid overload measured by BIVA is a frequent condition in critically ill patients--whether or not they undergo CRRT--and a significant predictor of mortality. Hence, hydration status should be considered as an additional prognosticator in the clinical management of the critically ill patient. (i) On the day of ICU admittance, patients showed a marked tendency to overhydration (>70% of total). This tendency was more pronounced in patients on CRRT. (ii) Hyperhydration persisted during the ICU stay. Patients who underwent CRRT showed significantly higher hyperhydration from the 2nd day of hospitalization. (iii) Nonsurvivors showed worse hyperhydration

  16. Randomized trial of bioelectrical impedance analysis versus clinical criteria for guiding ultrafiltration in hemodialysis patients: effects on blood pressure, hydration status, and arterial stiffness.

    Science.gov (United States)

    Onofriescu, Mihai; Mardare, Nicoleta Genoveva; Segall, Liviu; Voroneanu, Luminiţa; Cuşai, Claudiu; Hogaş, Simona; Ardeleanu, Serban; Nistor, Ionuţ; Prisadă, Octavian Viorel; Sascău, Radu; Covic, Adrian

    2012-04-01

    Chronic fluid overload is common in maintenance hemodialysis (HD) patients and is associated with severe cardiovascular complications, such as arterial hypertension, left ventricular hypertrophy, congestive heart failure, and arrhythmia. Therefore, a crucial target of HD is to achieve the so-called dry weight; however, the best way to assess fluid status and dry weight is still unclear. Dry weight is currently determined in most dialysis units on a clinical basis, and it is commonly defined as the lowest body weight a patient can tolerate without developing intra-dialytic or inter-dialytic hypotension or other symptoms of dehydration. One of the most promising methods that have emerged in recent years is bioelectrical impedance analysis (BIA), which estimates body composition, including hydration status, by measuring the body's resistance and reactance to electrical current. Our objective was to study the effect BIA-guided versus clinical-guided ultrafiltration on various cardiovascular disease risk factors and markers in HD patients. We included 135 HD patients from a single center in a prospective study, aiming to compare the long-term (12 months) effect of BIA-based versus clinical-based assessment of dry weight on blood pressure (BP), pulse wave velocity (PWV), and serum N-terminal fragment of B-type natriuretic peptide (NT-proBNP). The body composition was measured using the portable whole-body multifrequency BIA device, Body Composition Monitor-BCM(®) (Fresenius Medical Care, Bad Homburg, Germany). In the "clinical" group there were no changes in BP, body mass index (BMI), and body fluids. The PWV increased from 7.9 ± 2.5 to 9.2 ± 3.6 m/s (P = 0.002), whereas serum NT-proBNP decreased from 5,238 to 3,883 pg/ml (P = 0.05). In the "BIA" group, BMI and body volumes also did not change; however, there was a significant decrease in both systolic BP, from 144.6 ± 14.7 to 135.3 ± 17.8 mmHg (P < 0.001), and diastolic BP, from 79.5 ± 9.7 to 73.2 ± 11.1 mmHg (P

  17. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Federica Villa

    2016-05-01

    Full Text Available Bioelectrical Impedance Spectroscopy (BIS allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously.

  18. Total and Segmental Body Composition Examination in Collegiate Football Players Using Multifrequency Bioelectrical Impedance Analysis and Dual X-ray Absorptiometry.

    Science.gov (United States)

    Raymond, Christiana J; Dengel, Donald R; Bosch, Tyler A

    2018-03-01

    Raymond, CJ, Dengel, DR, and Bosch, TA. Total and segmental body composition examination in collegiate football players using multifrequency bioelectrical impedance analysis and dual X-ray absorptiometry. J Strength Cond Res 32(3): 772-782, 2018-The current study examined the influence of player position on the agreement between multifrequency bioelectrical impedance analysis (MfBIA) and dual X-ray absorptiometry (DXA) when assessing total and segmental percent body fat (BF%), fat mass (FM), and fat-free mass (FFM) in National Collegiate Athletic Association Division I collegiate football athletes. Forty-four male collegiate athletes (age = 19 ± 1 year; height = 1.9 ± 1.0 m; and body mass = 106.4 ± 18.8 kg) participated. Player positions included: offensive linemen (OL; n = 7), tight ends (TE; n = 4), wide receivers (WR; n = 9), defensive linemen (DL; n = 6), defensive backs (DB; n = 8), linebackers (LB; n = 6), and running backs (RB; n = 4). Total and segmental body composition measured using MfBIA were compared with values obtained using DXA. Compared with DXA, MfBIA underestimated BF% (3.0 ± 3.8%), total FM (2.5 ± 4.3 kg), arm FM (0.4 ± 0.8 kg), arm FFM (1.4 ± 0.9 kg), leg FM (2.8 ± 2.0 kg), and leg FFM (5.4 ± 2.4 kg) (all p FFM (-2.4 ± 4.5 kg) (p FFM), ±3.83 kg (leg FM), ±4.62 kg (leg FFM), and ±8.83 kg (total FFM). No significant differences were observed between devices for trunk FM (-0.3 ± 3.0 kg; p = 0.565) and trunk FFM (0.4 ± 2.4 kg; p = 0.278), with LOAs of ±5.92 and ±4.69 kg, respectively. Player position significantly affected all between-device mean body composition measurement differences (adjusted p ≤ 0.05), with OL demonstrating the greatest effect on each variable. Therefore, MfBIA does not seem accurate in examining between-player body composition in college football players.

  19. Ratio of muscle mass to fat mass assessed by bioelectrical impedance analysis is significantly correlated with liver fat accumulation in patients with type 2 diabetes mellitus.

    Science.gov (United States)

    Kurinami, Noboru; Sugiyama, Seigo; Morita, Ayami; Yoshida, Akira; Hieshima, Kunio; Miyamoto, Fumio; Kajiwara, Keizo; Jinnouch, Katsunori; Jinnouchi, Tomio; Jinnouchi, Hideaki

    2018-05-01

    Obesity and ectopic fat accumulation are important conditions of type 2 diabetes mellitus (T2DM). Our aim was to determine whether bioelectrical impedance body composition analysis combined with blood test results could estimate liver ectopic fat accumulation in patients with treatment-naïve T2DM. Subjects were 119 untreated T2DM patients. Computed tomography scans were performed to calculate the liver to spleen attenuation ratio (L/S ratio) as a measure of liver fat accumulation, with excess liver fat accumulation defined as an L/S ratio analysis using InBody770. The Nagelkerke R 2 test showed that the muscle mass/fat mass ratio (muscle/fat ratio) was the most suitable variable among anthropometric factors and body component indexes for estimating liver fat accumulation. The muscle/fat ratio was significantly correlated with the L/S ratio (ρ = 0.4386, P analysis showed that the muscle/fat ratio (odds ratio 0.40, 95% confidence interval 0.22-0.73, P ratio 1.06, 95% confidence interval 1.02-1.10, P analysis, the cutoff value of the muscle/fat ratio for excess liver fat accumulation was 2.34. In patients with treatment-naïve T2DM, the muscle/fat ratio and ALT are useful for estimating the presence of excess liver fat accumulation in daily clinical practice. Copyright © 2018. Published by Elsevier B.V.

  20. Single- and multi-frequency bioelectrical impedance analyses to analyse body composition in maintenance haemodialysis patients: comparison with dual-energy x-ray absorptiometry

    International Nuclear Information System (INIS)

    Donadio, C; Halim, A Ben; Caprio, F; Grassi, G; Khedr, B; Mazzantini, M

    2008-01-01

    The aim of this study was to evaluate the adequacy of single-frequency (sf-BIA) and multi-frequency bioelectrical impedance analyses (mf-BIA), in comparison with dual-energy x-ray absorptiometry (DXA), to evaluate body composition in maintenance haemodialysis (MHD) patients. Body composition of 27 adult MHD patients (9 f, 18 m), BMI 17.5–34.4 kg m −2 , was examined with DXA and BIA, with two different sf-BIA and 1 mf-BIA analysers. Biochemical markers of nutritional status and adequacy of dialytic treatment were also determined. Fat mass (FM) estimated by the different BIA analysers was found to be slightly but significantly higher than FM measured by DXA. In contrast, fat-free mass (FFM) obtained with BIA was found to be slightly but significantly lower than FFM DXA. No significant differences were found between LBM-DXA (that is FFM-DXA minus bone mass) and the different FFM BIA. The lowest mean prediction error versus DXA values was found with sf1BIA. In any case, a close correlation was found between all BIA values and DXA values, particularly for FFM. Furthermore, FFM and LBM results were significantly correlated with serum creatinine, which in MHD patients is an indicator of muscle mass. These results indicate that BIA can be used to evaluate body composition in MHD patients

  1. Preoperative and postoperative agreement in fat free mass (FFM) between bioelectrical impedance spectroscopy (BIS) and dual-energy X-ray absorptiometry (DXA) in patients undergoing cardiac surgery.

    Science.gov (United States)

    van Venrooij, Lenny M W; Verberne, Hein J; de Vos, Rien; Borgmeijer-Hoelen, Mieke M M J; van Leeuwen, Paul A M; de Mol, Bas A J M

    2010-12-01

    To measure undernutrition in terms of fat free mass (FFM), there are several options. The aim of this study was to assess agreement in FFM between the portable, bedside bioelectrical impedance spectrometry (BIS) and relatively expensive, non-portable dual-energy X-ray absorptiometry (DXA) in patients undergoing cardiac surgery. In a prospective study, body composition measurements by BIS and DXA were performed two weeks prior and two months after cardiac surgery. Preoperative and postoperative agreement in FFM between BIS and DXA were analyzed with Bland and Altman plots. Twenty-six patients were analyzed. BIS overestimated preoperative and postoperative FFM by 2 kg compared to DXA (2.3 kg (95%CI: -3.5-8.1 kg) and 2.1 kg (95%CI: -4.5-8.7 kg), respectively). BIS underestimated FFM change by -0.5% (95%CI: -8.4-7.5%). There is a large inter-individual variation between BIS and DXA. This hinders the interchange-ability of BIS and DXA in routine clinical practice and may lead to misclassifications and thereby inappropriate nutritional treatment and possible postoperative complications. To evaluate nutritional therapy in patients undergoing cardiac surgery, we advocate the use of DXA assessed FFM in parallel to BIS assessed extracellular and intracellular water and FFM. Copyright © 2010 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  2. The Impact of Feet Callosities, Arm Posture, and Usage of Electrolyte Wipes on Body Composition by Bioelectrical Impedance Analysis in Morbidly Obese Adults.

    Science.gov (United States)

    Roekenes, Jessica; Strømmen, Magnus; Kulseng, Bård; Martins, Catia

    2015-01-01

    This study evaluated the impact of feet callosities, arm posture, and use of electrolyte wipes on body composition measurements by bioelectrical impedance analysis (BIA) in morbidly obese adults. 36 morbidly obese patients (13 males, aged 28-70 years, BMI 41.6 ± 4.3 kg/m2) with moderate/severe feet callosities participated in this study. Body composition (percent body fat (%BF)) was measured while fasting using multi-frequency BIA (InBody 720®), before and after removal of callosities, with and without InBody® electrolyte wipes and custom-built auxiliary pads (to assess arm posture impact). Results from BIA were compared to air displacement plethysmography (ADP, BodPod®). Median %BF was significantly higher with auxiliary pads than without (50.1 (interquartile range 8.2) vs. 49.3 (interquartile range 9.1); p interquartile range 9.1) vs. 50.0 (interquartile range 7.9); NS) or use of wipes (49.6 (interquartile range 8.5) vs. 49.3 (interquartile range 9.1); NS). No differences in %BF were found between BIA and ADP (49.1 (IQR: 8.9) vs. 49.3 (IQR: 9.1); NS). Arm posture has a significant impact on %BF assessed by BIA, contrary to the presence of feet callosities and use of electrolyte wipes. Arm posture standardization during BIA for body composition assessment is, therefore, recommended. © 2015 S. Karger GmbH, Freiburg.

  3. Method for conducting nonlinear electrochemical impedance spectroscopy

    Science.gov (United States)

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  4. Bioelectrical impedance values among indigenous children and adolescents in Rio Grande do Sul, Brazil Valores de impedancia bioeléctrica en niños y adolescentes indígenas en Rio Grande do Sul, Brasil

    Directory of Open Access Journals (Sweden)

    Laura Augusta Barufaldi

    2011-07-01

    Full Text Available OBJECTIVE: To describe the nutritional status of indigenous children and adolescents in Rio Grande do Sul, Brazil, through bioelectrical values, and to compare the nutritional classifications of the anthropometric method to those of the body composition method. METHODS: A cross-sectional survey was conducted of 3 204 subjects at 35 schools in the 12 Kaingang indigenous lands of Rio Grande do Sul, Brazil. Following World Health Organization recommendations, the weight and height (H of each subject was measured twice and the body mass index/age (BMI/A was classified. Body composition was assessed by Bioelectrical Impedance Vector Analysis (BIVA. Resistance (R and reactance (Xc were estimated using a bioelectrical impedance analyzer. Divergences between these two methods were performed on RXc graph. RESULTS: Of the sample, 56.8% were adolescents and 50.6% were males. The mean values of phase angle were higher in adolescents, in males, and in individuals overweight by BMI/A. Mean values of R, Xc, R/H, and Xc/H were higher among children and among those with BMI/A OBJETIVO: Describir el estado nutricional de niños y adolescentes indígenas en Rio Grande do Sul, Brasil, mediante los valores de impedancia bioeléctrica y comparar las clasificaciones nutricionales del método antropométrico con las del método de composición corporal. MÉTODOS: Se llevó a cabo un estudio transversal en 3 204 participantes de 35 escuelas de los 12 territorios indígenas habitados por el pueblo kaingang (o guayaná del estado de Rio Grande do Sul (Brasil. Según las recomendaciones de la Organización Mundial de la Salud, se midió el peso y la talla (T de cada participante en dos oportunidades y se clasificó el índice de masa corporal (IMC según la edad. La composición corporal se evaluó mediante análisis vectorial de impedancia bioeléctrica. La resistencia (R y la reactancia (Xc se calcularon con un analizador de impedancia bioeléctrica. Las divergencias

  5. Application of bioelectrical impedance vector analysis (BIVA in dogs: a preliminary study on gender-related differences

    Directory of Open Access Journals (Sweden)

    Rebecca Ricci

    2010-01-01

    Full Text Available In this preliminary study, BIVA has been performed on 17 healthy Italian Hound dogs, 10 males (M and 7 females (F, in order to verify if gender-related differences can be detected. Only in F higher reactance (Xc values (F: 46.4 vs M: 37.7, P<0.05 and a significant negative correlation (-0.80, P<0.05 between BCS and resistance (R values were detected. 50%, 75% and 95% tolerance ellipses were calculated both in M and F using average Xc and R values standardized for withers height. Probably due to the low number of subjects used in the present study, the variability of the individual vector distribution (F: 79.6 vs M: 53.0Ohm/m, as well as the mean impedance vector lengtht (F: 548.2 vs M: 498.9Ohm/m, were similar in F and M. The gender-related difference in phase angle values was not significant (F: 0.168 vs M: 0.157, P=ns. In conclusion, the use of BIVA in dogs indicated differences between males and females which should be confirmed by a larger number of subjects.

  6. The additional value of bioelectrical impedance analysis-derived muscle mass as a screening tool in geriatric assessment for fall prevention.

    Science.gov (United States)

    Van Puyenbroeck, Karolien; Roelandts, Lieven; Van Deun, Thomas; Van Royen, Paul; Verhoeven, Veronique

    2012-01-01

    The decline in skeletal muscle in old age is a factor in the development of functional limitations. The objective of this study was to assess if there is a correlation between muscle mass based on bioelectrical impedance analysis (BIA) detection and the fall incidence in nursing home residents and to examine the risk factors for falling in nursing home residents. This prospective cohort study was part of a longitudinal study on nutritional issues in 52 nursing homes in Antwerp (Belgium) from October 2007 to April 2008. Two hundred and seventy-six people aged 65 years and older were included. Each subject was assessed with BIA, the timed get-up-and-go test, the Katz score, the Mini Nutritional Assessment - Short Form and the 36-Item Short Form Health Survey. The primary outcome parameter was fall incidence during the study. The prevalence of sarcopenia varied from 24.3 to 81.5% depending on which definition was used. No association was found between BIA-derived muscle mass and fall incidence. Logistic regression analysis showed that gait speed (odds ratio 1.029; p = 0.003) and mental health (odds ratio 0.981; p = 0.015) are significantly associated with fall incidence in nursing homes. A receiver operating characteristic curve showed that none of the BIA-derived muscle parameters are good predictors of the risk of falling. This study shows that there is no association between sarcopenia based on BIA and fall incidence and that BIA-derived muscle mass has no additional value in predicting fall incidents compared to the timed get-up-and-go test. Copyright © 2012 S. Karger AG, Basel.

  7. Cross-mode bioelectrical impedance analysis in a standing position for estimating fat-free mass validated against dual-energy x-ray absorptiometry.

    Science.gov (United States)

    Huang, Ai-Chun; Chen, Yu-Yawn; Chuang, Chih-Lin; Chiang, Li-Ming; Lu, Hsueh-Kuan; Lin, Hung-Chi; Chen, Kuen-Tsann; Hsiao, An-Chi; Hsieh, Kuen-Chang

    2015-11-01

    Bioelectrical impedance analysis (BIA) is commonly used to assess body composition. Cross-mode (left hand to right foot, Z(CR)) BIA presumably uses the longest current path in the human body, which may generate better results when estimating fat-free mass (FFM). We compared the cross-mode with the hand-to-foot mode (right hand to right foot, Z(HF)) using dual-energy x-ray absorptiometry (DXA) as the reference. We hypothesized that when comparing anthropometric parameters using stepwise regression analysis, the impedance value from the cross-mode analysis would have better prediction accuracy than that from the hand-to-foot mode analysis. We studied 264 men and 232 women (mean ages, 32.19 ± 14.95 and 34.51 ± 14.96 years, respectively; mean body mass indexes, 24.54 ± 3.74 and 23.44 ± 4.61 kg/m2, respectively). The DXA-measured FFMs in men and women were 58.85 ± 8.15 and 40.48 ± 5.64 kg, respectively. Multiple stepwise linear regression analyses were performed to construct sex-specific FFM equations. The correlations of FFM measured by DXA vs. FFM from hand-to-foot mode and estimated FFM by cross-mode were 0.85 and 0.86 in women, with standard errors of estimate of 2.96 and 2.92 kg, respectively. In men, they were 0.91 and 0.91, with standard errors of the estimates of 3.34 and 3.48 kg, respectively. Bland-Altman plots showed limits of agreement of -6.78 to 6.78 kg for FFM from hand-to-foot mode and -7.06 to 7.06 kg for estimated FFM by cross-mode for men, and -5.91 to 5.91 and -5.84 to 5.84 kg, respectively, for women. Paired t tests showed no significant differences between the 2 modes (P > .05). Hence, cross-mode BIA appears to represent a reasonable and practical application for assessing FFM in Chinese populations. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Effect of body build on the validity of predicted body fat from body mass index and bioelectrical impedance

    NARCIS (Netherlands)

    Snijder, M.B.; Kuyf, B.E.M.; Deurenberg, P.

    1999-01-01

    Background: Membrane fluidity is an important aspect of cellular physiology which may be manipulated by diet. Methods: We studied the effect of dietary fish oil on the membrane composition of erythrocytes and cheek cells, and on membrane fluidity of erythrocytes as assessed by fluorescence recovery

  9. DXA, bioelectrical impedance, ultrasonography and biometry for the estimation of fat and lean mass in cats during weight loss

    Directory of Open Access Journals (Sweden)

    Borges Naida C

    2012-07-01

    Full Text Available Abstract Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO, bioimpedance analysis (BIA and ultrasonography (US in cats, proposing equations to estimate fat (FM and lean (LM body mass, as compared to dual energy x-ray absorptiometry (DXA as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals, after 10% of weight loss (T1 and after 20% of weight loss (T2. Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p r2, 19 equations were selected (12 for FM, 7 for LM; however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed.

  10. Does the presence of an arteriovenous fistula alter changes in body water following hemodialysis as determined by multifrequency bioelectrical impedance assessment?

    Science.gov (United States)

    Panorchan, Kwanpeemai; Nongnuch, Arkom; El-Kateb, Sally; Goodlad, Cate; Davenport, Andrew

    2015-10-01

    Multifrequency bioelectrical impedance assessments (MFBIAs) aid clinical assessment of hydration status for hemodialysis (HD) patients. Many MFBIA devices are restricted to whole body measurements and as many patients dialyze using arteriovenous fistulas (AVFs), we wished to determine whether AVFs affected body water measurements. We reviewed pre- and post-HD segmental MFBIA measurements in 229 patients attending for midweek HD sessions. Up to 144 were dialyzed with a left arm AVF (L-AVF), 42 with a right arm AVF (R-AVF), and 43 by central venous access catheter (CVC). Water content and lean tissue were greater in the left compared to right arm in those patients with L-AVFs both pre and post dialysis (pre 2.1 ± 0.7 vs. 2.0 ± 0.7 L, and post 1.9 ± 0.6 vs. 1.8 ± 0.6 L and pre 2.65 ± 0.9 vs. 2.56 ± 0.8 kg, and post 2.34 ± 0.8 vs. 2.48 ± 0.8 vs. 2.34 ± 0.8 kg, respectively) and were also greater in the right compared to left arm for those patients dialyzing with R-AVFs (pre-HD 1.92 ± 0.5 vs. 1.86 ± 0.6 L and post-HD 1.79 ± 0.5 vs. 1.7 ± 0.5 L, and pre-HD 2.47 ± 0.6 vs. 2.38 ± 0.7 kg and post-HD 2.3 ± 0.74 vs. 1.28 ± 0.7 kg, respectively), all Ps Hemodialysis.

  11. Rf Discharge Impedance Measurements Using a New Method to Determine the Stray Impedances

    NARCIS (Netherlands)

    Bakker, L.P.; Kroesen, G.M.W.; Hoog, de F.J.

    1999-01-01

    The impedance of a capacitively coupled radio frequency discharge in a tubular fluorescent lamp filled with neon and mercury is measured. The stray impedances in the electrical network are determined using a new method that requires no extra instruments. The reflection of power is used to determine

  12. A Method Sustaining the Bioelectric, Biophysical, and Bioenergetic Function of Cultured Rabbit Atrial Cells

    Directory of Open Access Journals (Sweden)

    Noa Kirschner Peretz

    2017-08-01

    Full Text Available Culturing atrial cells leads to a loss in their ability to be externally paced at physiological rates and to maintain their shape. We aim to develop a culture method that sustains the shape of atrial cells along with their biophysical and bioenergetic properties in response to physiological pacing. We hypothesize that adding 2,3-Butanedione 2-monoxime (BDM, which inhibits contraction during the culture period, will preserve these biophysical and bioenergetic properties. Rabbit atrial cells were maintained in culture for 24 h in a medium enriched with a myofilament contraction inhibitor, BDM. The morphology and volume of the cells, including their ability to contract in response to 1–3 Hz electrical pacing, was maintained at the same level as fresh cells. Importantly, the cells could be successfully infected with a GFP adenovirus. Action potentials, Ca2+ transients, and local Ca2+ spark parameters were similar in the cultured and in fresh cells. Finally, these cultured cells' flavoprotein autofluorescence was maintained at a constant level in response to electrical pacing, a response similar to that of fresh cells. Thus, eliminating contraction during the culture period preserves the bioelectric, biophysical and bioenergetic properties of rabbit atrial myocytes. This method therefore has the potential to further improve our understanding of energetic and biochemical regulation in the atria.

  13. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Directory of Open Access Journals (Sweden)

    Claire M Nightingale

    Full Text Available BACKGROUND: Bioelectrical impedance analysis (BIA is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500. Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z; B: FFM = linear combination(height(2/Z; C: FFM = linear combination(height(2/Z+weight}. RESULTS: Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A. The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A. Consistent results were observed when the equations were applied to a large external data set. CONCLUSIONS: Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations

  14. Are Ethnic and Gender Specific Equations Needed to Derive Fat Free Mass from Bioelectrical Impedance in Children of South Asian, Black African-Caribbean and White European Origin? Results of the Assessment of Body Composition in Children Study

    Science.gov (United States)

    Nightingale, Claire M.; Rudnicka, Alicja R.; Owen, Christopher G.; Donin, Angela S.; Newton, Sian L.; Furness, Cheryl A.; Howard, Emma L.; Gillings, Rachel D.; Wells, Jonathan C. K.; Cook, Derek G.; Whincup, Peter H.

    2013-01-01

    Background Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. Methods Cross-sectional study of children aged 8–10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500). Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z); B: FFM = linear combination(height2/Z); C: FFM = linear combination(height2/Z+weight)}. Results Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A). The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM) and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A). Consistent results were observed when the equations were applied to a large external data set. Conclusions Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations can

  15. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Science.gov (United States)

    Nightingale, Claire M; Rudnicka, Alicja R; Owen, Christopher G; Donin, Angela S; Newton, Sian L; Furness, Cheryl A; Howard, Emma L; Gillings, Rachel D; Wells, Jonathan C K; Cook, Derek G; Whincup, Peter H

    2013-01-01

    Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500). Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z); B: FFM = linear combination(height(2)/Z); C: FFM = linear combination(height(2)/Z+weight)}. Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A). The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM) and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A). Consistent results were observed when the equations were applied to a large external data set. Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations can misrepresent these ethnic differences.

  16. Modelling a coal subcrop using the impedance method

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.A.; Thiel, D.V.; O' Keefe, S.G. [Griffith University, Nathan, Qld. (Australia). School of Microelectronic Engineering

    2000-07-01

    An impedance model was generated for two coal subcrops in the Biloela and Middlemount areas (Queensland, Australia). The model results were compared with actual surface impedance data. It was concluded that the impedance method satisfactorily modelled the surface response of the coal subcrops in two dimensions. There were some discrepancies between the field data and the model results, due to factors such as the method of discretization of the solution space in the impedance model and the lack of consideration of the three-dimensional nature of the coal outcrops. 10 refs., 8 figs.

  17. Differences in body composition measured using the bioelectrical impedance analysis with steel and gel electrodes – on an example of professional fencers

    Directory of Open Access Journals (Sweden)

    Olga Mizera

    2018-03-01

    Full Text Available Introduction: Regular assessment of body composition in athletes is a key element of their nutritional status and general condition monitoring. Purpose: Analysis of differences in the impedance (I and body composition measurements performed by the use of analyzers with a constant current frequency of 50 kHz with steel and gel electrodes. Material and methods: Analysis were performed in experienced fencers by the use of analyzers: Tanita BC418MA (aT with steel electrodes (eT and Akern BIA101ASE (aA with gel electrodes (eA, eL, eT. During the first stage of the study in 48 athletes I, fat mass (FM and fat free mass (FFM were measured using aA with eB in a supine position and after 3 min using aT with eT in a standing position. Then 10 fencers were randomly selected. For them measurements were performed after 10, 13 and 16 min in a supine position using eA, eL, eB and then after 3 min in a standing one using eT. Intrinsic impedance of the 3 types of gel electrodes (eA, eL, eB were measured using aA. Results: The first stage. Differences in I, FM and FFM between eT and aA were observed (women: 101.4±52.2Ω, 1.2±2.1kg, -1.2±2.1kg, men: 98.8±27.5Ω, 1.1±1.5kg, -1.1±1.5kg, respectively. The second stage. In the subsequent measurements, differences in I were observed (women: eL-eA 3.8±1.8Ω, eB-eA 26.1±8.0Ω, eT-eA 154.4±40.6Ω;, men: of -0.7±9.4Ω, 11.1±9.2Ω, 107±36.3Ω, respectively. In both subgroups along with the increase in I, FM also increased, while  FFM decreased. Intrinsic impedance of the applied gel electrodes was measured and the differences between the results were reported (eL-eA 41.1±22.0Ω, eB-eL 138.4±20.7Ω, eB-eA 179.5Ω. As the intrinsic impedance of gel electrodes increased, an increase in the whole body I was observed. Conclusion: It seems that the observed differences in the whole body impedance were not only a simple effect of changes in a body position but they might have also been related to the intrinsic

  18. Validation of Standing Wave Liner Impedance Measurement Method, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hersh Acoustical Engineering, Inc. proposes to establish the feasibility and practicality of using the Standing Wave Method (SWM) to measure the impedance of...

  19. Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

    DEFF Research Database (Denmark)

    Hendel, H W; Gotfredsen, A; Højgaard, L

    1996-01-01

    ). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis....... The results of the BIA equations varied widely; FFM was generally overestimated by BIA as compared with DXA and TBK before and after weight loss. During weight loss, the FFM did not change, as estimated by DXA (1.3 +/- 2.3 kg, p > 0.05) and TBK (0.9 +/- 2.9 kg, p > 0.05). The recorded change in impedance (R......) was also insignificant. Three BIA equations from the literature, which were not specific for the degree of obesity in the present study group, predicted changes in FFM (from 0.5 + 3.6 to 2.4 +/- 4.4kg, p > 0.05) that were comparable with those estimated by the reference methods. Eight equations from...

  20. Nuclear EMP: stripline test method for measuring transfer impedance

    International Nuclear Information System (INIS)

    Miller, J.S.

    1975-11-01

    A method for measuring the transfer impedance of flat metal joints for frequencies to 100 MHz has been developed which makes use of striplines. The stripline method, which has similarities to the quadraxial method used for cylindrical components, is described and sets of test results are given. The transfer impedance of a simple joint is modeled as a spurious hyperbolic curve, and a close curve fit to transfer impedance test data from various samples is demonstrated for both the stripline and the quadraxial methods. Validity checks of the test data are discussed using the curve model and other criteria. The method was developed for testing riveted joints which form the avionics bays on B-1s. The joints must provide shielding from EMP currents

  1. Energy storage cell impedance measuring apparatus, methods and related systems

    Science.gov (United States)

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.

    2017-12-26

    Energy storage cell impedance testing devices, circuits, and related methods are disclosed. An energy storage cell impedance measuring device includes a sum of sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell. A method includes applying an SOS signal comprising a sum of sinusoidal current signals to the energy storage cell with the SOS current excitation circuit, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies. The method also includes measuring an electrical signal at a positive terminal and a negative terminal of the energy storage cell, and computing an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.

  2. Estimativa da massa muscular esquelética em mulheres idosas: validade da impedância bioelétrica Validity of bioelectrical impedance analysis for the estimation of skeletal muscle mass in elderly women

    Directory of Open Access Journals (Sweden)

    Cassiano Ricardo Rech

    2010-04-01

    Full Text Available O presente estudo tem como objetivos: a verificar a concordância entre os métodos da impedância bioelétrica (BIA e da absortometria radiológica de dupla energia (DXA para a estimativa da massa muscular esquelética (MME; e b analisar o poder preditivo de variáveis antropométricas e da BIA para a predição da MME em idosas. Foram avaliadas 120 mulheres (60 a 81 anos, residentes na região Sul do Brasil. Mensuraram-se as variáveis antropométricas (massa corporal e estatura; a resistência e hidratação dos tecidos livres de gordura foram medidas pela técnica da BIA tetrapolar (Biodinamics - BF-310, e pela DXA de corpo inteiro (Lunar Prodigy DF + 14319 Radiation e software 7.52.002 DPX-L. A diferença entre os métodos foi verificada pelo teste t pareado, análise dos resíduos e o coeficiente de correlação. O valor preditivo das variáveis antropométricas e de BIA foi verificado pela regressão linear múltipla, adotando nível de significância de p 0,01. Observou-se que a BIA subestimou em média 0,8kg (IC95%: -3,7; 2,0kg a MME, quando comparada com a DXA. Foi observada alta correlação entre os métodos (r² = 0,75; p The objectives of the present study were: a to determine the agreement between bioelectrical impedance analysis (BIA and dual-energy X-ray absorptiometry (DXA for the estimation of skeletal muscle mass (SMM, and b to analyze the predictive power of anthropometric variables and BIA for the prediction of SMM in elderly women. A total of 120 women (60 to 81 years, living in the southern region of Brazil, were studied. Anthropometric variables (body weight and height were measured. Resistance and hydration of fat-free tissues were measured by tetrapolar BIA (Biodynamics, BF-310 and by whole-body DXA (Lunar Prodigy DF + 14319 Radiation and DPX-L software, version 7.52.002. Differences between methods were determined using the paired t-test, analysis of residuals and correlation coefficient. The predictive value of the

  3. Multi-Electrode Impedance Method for Detection of Regional Ventilation

    International Nuclear Information System (INIS)

    Furuya, Norio; Sakamoto, Katsuyuki

    2013-01-01

    By means of computer simulation and experiment, we investigated the feasibility of simultaneously measuring the transfer impedance changes in the right apex, left apex, right base and left base of the lungs using the multi-electrode impedance method. To obtain the transfer impedance in each region, while suppressing the effects of other regions, changing the amplitude and polarity of the applied current must localize the high sensitivity areas in the interest region. Twelve current and eight voltage electrodes were equidistantly arranged on the anterior and posterior chest walls. The amplitudes and polarities of the currents that were simultaneously applied to the current electrodes, and which provided the appropriate sensitivity distribution, were theoretically obtained. The effects of the localized sensitivity distribution were verified by comparing the simulation results of the investigated method with the results of the conventional four-electrode method. From the results of the computer simulation, we developed a multi-electrode impedance pneumography and applied it to healthy adult volunteers who were both in sitting position and in left decubitus. We found that the measurement results were physiologically reasonable.

  4. Estimating surface acoustic impedance with the inverse method.

    Science.gov (United States)

    Piechowicz, Janusz

    2011-01-01

    Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.

  5. Transverse impedance measurement using response matrix fit method at APS

    International Nuclear Information System (INIS)

    Sajaev, V.

    2007-01-01

    The Advanced Photon Source (APS) is a third-generation synchrotron light source based on a 7-GeV electron storage ring. In third-generation light sources the synchrotron radiation is mainly produced in undulators. In order to achieve high photon flux and tunability, the magnet gap in undulators has to be as small as possible. Therefore, the undulators are installed on dedicated small-gap insertion device (ID) vacuum chambers. APS has thirty-five 5-m-long straight sections available for undulators. At the time of the measurements, there were 31 straight sections occupied with various insertion devices, and 4 straight sections were still empty. Most of the ID vacuum chambers have a 8-mm in-vacuum gap, and two chambers have a 5-mm gap. These narrow-gap vacuum chambers are believed to be the main source of the transverse impedance of the machine. One can measure the combined impedance by measuring the transverse tune slope with single-bunch current. Comparing this slope before and after installation of the narrow-gap vacuum chamber, one can deduce the impedance of the chamber. It is difficult to accurately measure the change in the tune slope after one or a few new ID chambers are installed. If several identical ID vacuum chambers are installed over a period of time, then one can estimate the contribution of one ID chamber. Over the last few years there have been a number of attempts to measure the impedance of separate components of accelerators. Phase-advance measurements from beam position monitor (BPM) turn-by-turn histories were used at LEP to measure the impedance distribution around the ring. Researches at LEP were able to fit average impedance in the long sections of the LEP arc and determine the impedance of the rf sections. The method was tried at APS; however, the accuracy of the measurements was not enough to determine the small impedance of a single ID vacuum chamber. There is also a different approach that uses local orbit bumps to probe different parts

  6. Impedance Method for Leak Detection in Zigzag Pipelines

    Science.gov (United States)

    Lay-Ekuakille, A.; Vergallo, P.; Trotta, A.

    2010-01-01

    Transportation of liquids is a primary aspect of human life. The most important infrastructure used accordingly is the pipeline. It serves as an asset for transporting different liquids and strategic goods. The latter are for example: chemical substances, oil, gas and water. Thus, it is necessary to monitor such infrastructures by means of specific tools. Leakage detection methods are used to reveal liquid leaks in pipelines for many applications, namely, waterworks, oil pipelines, industry heat exchangers, etc. The configuration of pipelines is a key issue because it impacts on the effectiveness of the method to be used and, consequently, on the results to be counterchecked. This research illustrated an improvement of the impedance method for zigzag pipeline by carrying out an experimental frequency analysis that has been compared with other methods based on frequency response. Hence, the impedance method is generally used for simple (straight) pipeline configurations because complicated pipelines with many curves introduce difficulties and major uncertainties in the calculation of characteristic impedance and in the statement of boundary conditions. The paper illustrates the case of a water pipeline where the leakage is acquired thanks to pressure transducers.

  7. Recent Progress on the Factorization Method for Electrical Impedance Tomography

    Directory of Open Access Journals (Sweden)

    Bastian Harrach

    2013-01-01

    method was introduced by Kirsch for inverse scattering problems and extended to electrical impedance tomography (EIT by Brühl and Hanke. Since these pioneering works, substantial progress has been made on the theoretical foundations of the method. The necessary assumptions have been weakened, and the proofs have been considerably simplified. In this work, we aim to summarize this progress and present a state-of-the-art formulation of the Factorization Method for EIT with continuous data. In particular, we formulate the method for general piecewise analytic conductivities and give short and self-contained proofs.

  8. Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

    DEFF Research Database (Denmark)

    Hendel, H W; Gotfredsen, A; Højgaard, L

    1996-01-01

    A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK). These measu......A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK......). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis....... The results of the BIA equations varied widely; FFM was generally overestimated by BIA as compared with DXA and TBK before and after weight loss. During weight loss, the FFM did not change, as estimated by DXA (1.3 +/- 2.3 kg, p > 0.05) and TBK (0.9 +/- 2.9 kg, p > 0.05). The recorded change in impedance (R...

  9. A dielectrophoresis-impedance method for protein detection and analysis

    Science.gov (United States)

    Mohamad, Ahmad Sabry; Hamzah, Roszymah; Hoettges, Kai F.; Hughes, Michael Pycraft

    2017-01-01

    Dielectrophoresis (DEP) has increasingly been used for the assessment of the electrical properties of molecular scale objects including proteins, DNA, nanotubes and nanowires. However, whilst techniques have been developed for the electrical characterisation of frequency-dependent DEP response, biomolecular study is usually limited to observation using fluorescent markers, limiting its applicability as a characterisation tool. In this paper we present a label-free, impedance-based method of characterisation applied to the determination of the electrical properties of colloidal protein molecules, specifically Bovine Serum Albumin (BSA). By monitoring the impedance between electrodes as proteins collect, it is shown to be possible to observe multi-dispersion behaviour. A DEP dispersion exhibited at 400 kHz is attributable to the orientational dispersion of the molecule, whilst a second, higher-frequency dispersion is attributed to a Maxwell-Wagner type dispersion; changes in behaviour with medium conductivity suggest that this is strongly influenced by the electrical double layer surrounding the molecule.

  10. Iterative Reconstruction Methods for Hybrid Inverse Problems in Impedance Tomography

    DEFF Research Database (Denmark)

    Hoffmann, Kristoffer; Knudsen, Kim

    2014-01-01

    For a general formulation of hybrid inverse problems in impedance tomography the Picard and Newton iterative schemes are adapted and four iterative reconstruction algorithms are developed. The general problem formulation includes several existing hybrid imaging modalities such as current density...... impedance imaging, magnetic resonance electrical impedance tomography, and ultrasound modulated electrical impedance tomography, and the unified approach to the reconstruction problem encompasses several algorithms suggested in the literature. The four proposed algorithms are implemented numerically in two...

  11. Impedance adaptation methods of the piezoelectric energy harvesting

    Science.gov (United States)

    Kim, Hyeoungwoo

    In this study, the important issues of energy recovery were addressed and a comprehensive investigation was performed on harvesting electrical power from an ambient mechanical vibration source. Also discussed are the impedance matching methods used to increase the efficiency of energy transfer from the environment to the application. Initially, the mechanical impedance matching method was investigated to increase mechanical energy transferred to the transducer from the environment. This was done by reducing the mechanical impedance such as damping factor and energy reflection ratio. The vibration source and the transducer were modeled by a two-degree-of-freedom dynamic system with mass, spring constant, and damper. The transmissibility employed to show how much mechanical energy that was transferred in this system was affected by the damping ratio and the stiffness of elastic materials. The mechanical impedance of the system was described by electrical system using analogy between the two systems in order to simply the total mechanical impedance. Secondly, the transduction rate of mechanical energy to electrical energy was improved by using a PZT material which has a high figure of merit and a high electromechanical coupling factor for electrical power generation, and a piezoelectric transducer which has a high transduction rate was designed and fabricated. The high g material (g33 = 40 [10-3Vm/N]) was developed to improve the figure of merit of the PZT ceramics. The cymbal composite transducer has been found as a promising structure for piezoelectric energy harvesting under high force at cyclic conditions (10--200 Hz), because it has almost 40 times higher effective strain coefficient than PZT ceramics. The endcap of cymbal also enhances the endurance of the ceramic to sustain ac load along with stress amplification. In addition, a macro fiber composite (MFC) was employed as a strain component because of its flexibility and the high electromechanical coupling

  12. Methods for calculating the electrode position Jacobian for impedance imaging.

    Science.gov (United States)

    Boyle, A; Crabb, M G; Jehl, M; Lionheart, W R B; Adler, A

    2017-03-01

    Electrical impedance tomography (EIT) or electrical resistivity tomography (ERT) current and measure voltages at the boundary of a domain through electrodes. The movement or incorrect placement of electrodes may lead to modelling errors that result in significant reconstructed image artifacts. These errors may be accounted for by allowing for electrode position estimates in the model. Movement may be reconstructed through a first-order approximation, the electrode position Jacobian. A reconstruction that incorporates electrode position estimates and conductivity can significantly reduce image artifacts. Conversely, if electrode position is ignored it can be difficult to distinguish true conductivity changes from reconstruction artifacts which may increase the risk of a flawed interpretation. In this work, we aim to determine the fastest, most accurate approach for estimating the electrode position Jacobian. Four methods of calculating the electrode position Jacobian were evaluated on a homogeneous halfspace. Results show that Fréchet derivative and rank-one update methods are competitive in computational efficiency but achieve different solutions for certain values of contact impedance and mesh density.

  13. Impedance method for measuring shear elasticity of liquids

    Science.gov (United States)

    Badmaev, B. B.; Dembelova, T. S.; Damdinov, B. B.; Gulgenov, Ch. Zh.

    2017-11-01

    Experimental results of studying low-frequency (74 kHz) shear elasticity of polymer liquids by the impedance method (analogous to the Mason method) are presented. A free-volume thick liquid layer is placed on the horizontal surface of a piezoelectric quartz crystal with dimensions 34.7 × 12 × 5.5 cm. The latter performs tangential vibrations at resonance frequency. The liquid layer experiences shear strain, and shear waves should propagate in it. From the theory of the method, it follows that, with an increase in the layer thickness, both real and imaginary resonance frequency shifts should exhibit damped oscillations and tend to limiting values. For the liquids under study, the imaginary frequency shift far exceeds the real one, which testifies to the presence of bulk shear elasticity.

  14. A comparison between handgrip strength, upper limb fat free mass by segmental bioelectrical impedance analysis (SBIA) and anthropometric measurements in young males

    International Nuclear Information System (INIS)

    Gonzalez-Correa, C H; Caicedo-Eraso, J C; Varon-Serna, D R

    2013-01-01

    The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r 2 = 0.60) and poorer between physical and electrical volume (r 2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt 2 = 0.07) and electrical (r 2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.

  15. Bioelectrical impedance for detecting and monitoring lymphedema in patients with breast cancer. Preliminary results of the florence nightingale breast study group.

    Science.gov (United States)

    Erdogan Iyigun, Zeynep; Selamoglu, Derya; Alco, Gul; Pilancı, Kezban Nur; Ordu, Cetin; Agacayak, Filiz; Elbüken, Filiz; Bozdogan, Atilla; Ilgun, Serkan; Guler Uysal, Fusun; Ozmen, Vahit

    2015-03-01

    The aim of this study was to evaluate the efficacy of bioimpedance spectroscopy for the follow-up of patients with lymphedema in Turkey and its benefits in the diagnosis of stage 0, 1, and 2 lymphedema in patients who are under treatment for breast cancer. Thirty-seven female patients with breast cancer who underwent surgical procedures in our Breast Health Centre were followed up for lymphedema using bioimpedance, and clinical measurements were taken for a minimum period of 1 year at 3-month intervals. Patients who had been monitored regularly between November, 2011, and September, 2013, were enrolled to the study. In total, 8 patients developed lymphedema with an overall rate of 21.6%. Among the 8 patients who developed lymphedema, 4 had Stage 2, 1 had Stage 1, and 3 had Stage 0 lymphedema. Stage 0 lymphedema could not be detected with clinical measurements. During the patients' 1-year follow-up period using measurements of bioimpedance, a statistically significant relationship was observed between the occurrence of lymphedema and the disease characteristics. including the number of the extracted and remaining lymph nodes and the region of radiotherapy (p=0.042, p=0.024, p=0.040). Bioimpedance analysis seems to be a practical and reliable method for the early diagnosis of lymphedema. It is believed that regular monitoring of patients in the high-risk group using bioimpedance analyses increases the ability to treat lymphedema.

  16. A dielectrophoresis-impedance method for protein detection and analysis

    Directory of Open Access Journals (Sweden)

    Ahmad Sabry Mohamad

    2017-01-01

    Full Text Available Dielectrophoresis (DEP has increasingly been used for the assessment of the electrical properties of molecular scale objects including proteins, DNA, nanotubes and nanowires. However, whilst techniques have been developed for the electrical characterisation of frequency-dependent DEP response, biomolecular study is usually limited to observation using fluorescent markers, limiting its applicability as a characterisation tool. In this paper we present a label-free, impedance-based method of characterisation applied to the determination of the electrical properties of colloidal protein molecules, specifically Bovine Serum Albumin (BSA. By monitoring the impedance between electrodes as proteins collect, it is shown to be possible to observe multi-dispersion behaviour. A DEP dispersion exhibited at 400 kHz is attributable to the orientational dispersion of the molecule, whilst a second, higher-frequency dispersion is attributed to a Maxwell-Wagner type dispersion; changes in behaviour with medium conductivity suggest that this is strongly influenced by the electrical double layer surrounding the molecule.

  17. Evaluation of electrical broad bandwidth impedance spectroscopy as a tool for body composition measurement in cows in comparison with body measurements and the deuterium oxide dilution method.

    Science.gov (United States)

    Schäff, C T; Pliquett, U; Tuchscherer, A; Pfuhl, R; Görs, S; Metges, C C; Hammon, H M; Kröger-Koch, C

    2017-05-01

    Body fatness and degree of body fat mobilization in cows vary enormously during their reproduction cycle and influence energy partitioning and metabolic adaptation. The objective of the study was to test bioelectrical impedance spectroscopy (BIS) as a method for predicting fat depot mass (FDM), in living cows. The FDM is defined as the sum of subcutaneous, omental, mesenteric, retroperitoneal, and carcass fat mass. Bioelectrical impedance spectroscopy is compared with the prediction of FDM from the deuterium oxide (DO) dilution method and from body conformation measurements. Charolais × Holstein Friesian (HF; = 18; 30 d in milk) crossbred cows and 2 HF (lactating and nonlactating) cows were assessed by body conformation measurements, BIS, and the DO dilution method. The BCS of cows was a mean of 3.68 (SE 0.64). For the DO dilution method, a bolus of 0.23 g/kg BW DO (60 atom%) was intravenously injected and deuterium (D) enrichment was analyzed in plasma and whey by stabile isotope mass spectrometry, and total body water content was calculated. Impedance measurement was performed using a 4-electrode interface and time domain-based measurement system consisting of a voltage/current converter for applying current stimulus and an amplifier for monitoring voltage across the sensor electrodes. For the BIS, we used complex impedances over three frequency decades that delivers information on intra- and extracellular water and capacity of cell membranes. Impedance data (resistance of extra- and intracellular space, cell membrane capacity, and phase angle) were extracted 1) by simple curve fit to extract the resistance at direct current and high frequency and 2) by using an electrical equivalent circuit. Cows were slaughtered 7 d after BIS and D enrichment measurements and dissected for the measurement of FDM. Multiple linear regression analyses were performed to predict FDM based on data obtained from body conformation measurements, BIS, and D enrichment, and applied

  18. A Method Sustaining the Bioelectric, Biophysical, and Bioenergetic Function of Cultured Rabbit Atrial Cells

    OpenAIRE

    Noa Kirschner Peretz; Sofia Segal; Limor Arbel-Ganon; Ronen Ben Jehuda; Ronen Ben Jehuda; Yuval Shemer; Yuval Shemer; Binyamin Eisen; Binyamin Eisen; Moran Davoodi; Ofer Binah; Ofer Binah; Yael Yaniv

    2017-01-01

    Culturing atrial cells leads to a loss in their ability to be externally paced at physiological rates and to maintain their shape. We aim to develop a culture method that sustains the shape of atrial cells along with their biophysical and bioenergetic properties in response to physiological pacing. We hypothesize that adding 2,3-Butanedione 2-monoxime (BDM), which inhibits contraction during the culture period, will preserve these biophysical and bioenergetic properties. Rabbit atrial cells w...

  19. Electrical impedance spectroscopy (EIS)-based evaluation of biological tissue phantoms to study multifrequency electrical impedance tomography (Mf-EIT) systems

    KAUST Repository

    Bera, Tushar Kanti; Nagaraju, J.; Lubineau, Gilles

    2016-01-01

    . In this direction the impedance responses of the saline solution (background) and a number vegetable and fruit tissues (inhomogeneities) are studied with electrical impedance spectroscopy (EIS) and the frequency responses of bioelectrical impedance and conductivity

  20. An Effective Measured Data Preprocessing Method in Electrical Impedance Tomography

    Directory of Open Access Journals (Sweden)

    Chenglong Yu

    2014-01-01

    Full Text Available As an advanced process detection technology, electrical impedance tomography (EIT has widely been paid attention to and studied in the industrial fields. But the EIT techniques are greatly limited to the low spatial resolutions. This problem may result from the incorrect preprocessing of measuring data and lack of general criterion to evaluate different preprocessing processes. In this paper, an EIT data preprocessing method is proposed by all rooting measured data and evaluated by two constructed indexes based on all rooted EIT measured data. By finding the optimums of the two indexes, the proposed method can be applied to improve the EIT imaging spatial resolutions. In terms of a theoretical model, the optimal rooting times of the two indexes range in [0.23, 0.33] and in [0.22, 0.35], respectively. Moreover, these factors that affect the correctness of the proposed method are generally analyzed. The measuring data preprocessing is necessary and helpful for any imaging process. Thus, the proposed method can be generally and widely used in any imaging process. Experimental results validate the two proposed indexes.

  1. A parametric framework for modelling of bioelectrical signals

    CERN Document Server

    Mughal, Yar Muhammad

    2016-01-01

    This book examines non-invasive, electrical-based methods for disease diagnosis and assessment of heart function. In particular, a formalized signal model is proposed since this offers several advantages over methods that rely on measured data alone. By using a formalized representation, the parameters of the signal model can be easily manipulated and/or modified, thus providing mechanisms that allow researchers to reproduce and control such signals. In addition, having such a formalized signal model makes it possible to develop computer tools that can be used for manipulating and understanding how signal changes result from various heart conditions, as well as for generating input signals for experimenting with and evaluating the performance of e.g. signal extraction methods. The work focuses on bioelectrical information, particularly electrical bio-impedance (EBI). Once the EBI has been measured, the corresponding signals have to be modelled for analysis. This requires a structured approach in order to move...

  2. Electromechanical impedance method to assess dental implant stability

    International Nuclear Information System (INIS)

    Tabrizi, Aydin; Rizzo, Piervincenzo; Ochs, Mark W

    2012-01-01

    The stability of a dental implant is a prerequisite for supporting a load-bearing prosthesis and establishment of a functional bone–implant system. Reliable and noninvasive methods able to assess the bone interface of dental and orthopedic implants (osseointegration) are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, we propose the electromechanical impedance method as a novel approach for the assessment of dental implant stability. Nobel Biocare ® implants with a size of 4.3 mm diameter ×13 mm length were placed inside bovine bones that were then immersed in a solution of nitric acid to allow material degradation. The degradation simulated the inverse process of bone healing. The implant–bone systems were monitored by bonding a piezoceramic transducer (PZT) to the implants’ abutment and measuring the admittance of the PZT over time. It was found that the PZT’s admittance and the statistical features associated with its analysis are sensitive to the degradation of the bones and can be correlated to the loss of calcium measured by means of the atomic absorption spectroscopy method. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of dental implant stability and integrity. (paper)

  3. Application of impedance spectroscopy method for analysis of benzanol fuels

    Directory of Open Access Journals (Sweden)

    Mamykin A. V.

    2015-06-01

    Full Text Available The authors have developed a method for express control of three component «gasoline-alcohol-water» fuel mixtures based on the spectral impedance investigation of benzanol mixture in the frequency range of 500 Hz — 10 kHz. A correlation dependence between the dielectric constant and the specific resistance of the fuel mixture on content of ethanol and water in the mixture has been found. On the basis of this dependence a calibration nomogram to quantify the gasoline and water-alcohol components content in the test benzanol fuel in the actual range of concentrations has been formed. The nomogram allows determining the water-alcohol and gasoline parts in the analyzed fuel with an error of no more than 1% vol., while the strength of water-alcohol solution is determined with an error of no more than 0.8% vol. The obtained nomogram can also give information about critical water content in the benzanol fuel to prevent its eventual phase separation. It is shown that the initial component composition of different gasoline brands has no significant effect on the electrical characteristics of the studied benzanol fuels, which makes the evaluation of alcohol and water content in the fuel sufficiently accurate. for practical applications.

  4. Modified coaxial wire method for measurement of transfer impedance of beam position monitors

    Science.gov (United States)

    Kumar, Mukesh; Babbar, L. K.; Deo, R. K.; Puntambekar, T. A.; Senecha, V. K.

    2018-05-01

    The transfer impedance is a very important parameter of a beam position monitor (BPM) which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables). This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.

  5. Modified coaxial wire method for measurement of transfer impedance of beam position monitors

    Directory of Open Access Journals (Sweden)

    Mukesh Kumar

    2018-05-01

    Full Text Available The transfer impedance is a very important parameter of a beam position monitor (BPM which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables. This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.

  6. Accurate position estimation methods based on electrical impedance tomography measurements

    Science.gov (United States)

    Vergara, Samuel; Sbarbaro, Daniel; Johansen, T. A.

    2017-08-01

    Electrical impedance tomography (EIT) is a technology that estimates the electrical properties of a body or a cross section. Its main advantages are its non-invasiveness, low cost and operation free of radiation. The estimation of the conductivity field leads to low resolution images compared with other technologies, and high computational cost. However, in many applications the target information lies in a low intrinsic dimensionality of the conductivity field. The estimation of this low-dimensional information is addressed in this work. It proposes optimization-based and data-driven approaches for estimating this low-dimensional information. The accuracy of the results obtained with these approaches depends on modelling and experimental conditions. Optimization approaches are sensitive to model discretization, type of cost function and searching algorithms. Data-driven methods are sensitive to the assumed model structure and the data set used for parameter estimation. The system configuration and experimental conditions, such as number of electrodes and signal-to-noise ratio (SNR), also have an impact on the results. In order to illustrate the effects of all these factors, the position estimation of a circular anomaly is addressed. Optimization methods based on weighted error cost functions and derivate-free optimization algorithms provided the best results. Data-driven approaches based on linear models provided, in this case, good estimates, but the use of nonlinear models enhanced the estimation accuracy. The results obtained by optimization-based algorithms were less sensitive to experimental conditions, such as number of electrodes and SNR, than data-driven approaches. Position estimation mean squared errors for simulation and experimental conditions were more than twice for the optimization-based approaches compared with the data-driven ones. The experimental position estimation mean squared error of the data-driven models using a 16-electrode setup was less

  7. IMPEDANCE METHOD OF MEASURING OF THE TITRATABLE ACIDITY OF YOGURT

    Directory of Open Access Journals (Sweden)

    Miroslav Vasilev

    2016-10-01

    Full Text Available In the present work are analyzed studies related to changes in the active impedance component of the dairy environment caused by the flow of lactic fermentation and coagulation of casein in milk. The aim of this work was to determine the relationship between the relative change of titratable acidity and the relative change of active impedance component of the dairy environment with lactic fermentation, causing coagulation of the casein in milk. . The data were interpolated with cubic spline, visualizing how when the fat content increases, the electrical resistance increases too. All data, collected during the tests would complement and be used for solving the optimization problem to determine the time of completion of the coagulation in future work.

  8. A New Method of On-line Grid Impedance Estimation for PV Inverter

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Asiminoaei, Lucian; Blaabjerg, Frede

    2004-01-01

    for on-line measuring the grid impedance is presented. The presented method requires no extra hardware being accommodated by typical PV inverters, sensors and CPU, to provide a fast and low cost approach of on-line impedance measurement. By injecting a non-characteristic harmonic current and measuring...

  9. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2004-01-01

    Analytical Method of Auxiliary Sources solutions for plane wave scattering by circular impedance cylinders are derived by transformation of the exact eigenfunction series solutions employing the Hankel function wave transformation. The analytical Method of Auxiliary Sources solution thus obtained...

  10. Bioelectric Signal Measuring System

    Science.gov (United States)

    Guadarrama-Santana, A.; Pólo-Parada, L.; García-Valenzuela, A.

    2015-01-01

    We describe a low noise measuring system based on interdigitated electrodes for sensing bioelectrical signals. The system registers differential voltage measurements in order of microvolts. The base noise during measurements was in nanovolts and thus, the sensing signals presented a very good signal to noise ratio. An excitation voltage of 1Vrms with 10 KHz frequency was applied to an interdigitated capacitive sensor without a material under test and to a mirror device simultaneously. The output signals of both devices was then subtracted in order to obtain an initial reference value near cero volts and reduce parasitic capacitances due to the electronics, wiring and system hardware as well. The response of the measuring system was characterized by monitoring temporal bioelectrical signals in real time of biological materials such as embryo chicken heart cells and bovine suprarenal gland cells.

  11. Perturbation method for calculation of narrow-band impedance and trapped modes

    International Nuclear Information System (INIS)

    Heifets, S.A.

    1987-01-01

    An iterative method for calculation of the narrow-band impedance is described for a system with a small variation in boundary conditions, so that the variation can be considered as a perturbation. The results are compared with numeric calculations. The method is used to relate the origin of the trapped modes with the degeneracy of the spectrum of an unperturbed system. The method also can be applied to transverse impedance calculations. 6 refs., 6 figs., 1 tab

  12. Impedance spectroscopy as a method for evaluation of lithium-thionyl chloride cells

    Energy Technology Data Exchange (ETDEWEB)

    Kanevskii, L.S.; Bagotzky, V.S.; Nizhnikovskii, E.A. [Frumkin Institute of Electrochemistry, Moscow (Russian Federation)

    1995-04-01

    Impedance spectroscopy was evaluated as a method for ascertaining the state of constituent components of Li-thionyl chloride cells. No unambiguous correlation between impedance characteristics and residual capacity was detected as a result of investigation of a large population of different size and capacity Li-thionyl chloride cells. Impedance studies of nonpolarized lithium electrodes in operating cells resulted in a conclusion that the diagnostics of Li-thionyl chloride cells is extremely difficult, due to the specific nature of lithium passivation in operating cells and the influence on this process exerted by sulfur dioxide generated during discharge.

  13. Ultrahigh impedance method to assess electrostatic accelerator performance

    Directory of Open Access Journals (Sweden)

    Nikolai R. Lobanov

    2015-06-01

    Full Text Available This paper describes an investigation of problem-solving procedures to troubleshoot electrostatic accelerators. A novel technique to diagnose issues with high-voltage components is described. The main application of this technique is noninvasive testing of electrostatic accelerator high-voltage grading systems, measuring insulation resistance, or determining the volume and surface resistivity of insulation materials used in column posts and acceleration tubes. In addition, this technique allows verification of the continuity of the resistive divider assembly as a complete circuit, revealing if an electrical path exists between equipotential rings, resistors, tube electrodes, and column post-to-tube conductors. It is capable of identifying and locating a “microbreak” in a resistor and the experimental validation of the transfer function of the high impedance energy control element. A simple and practical fault-finding procedure has been developed based on fundamental principles. The experimental distributions of relative resistance deviations (ΔR/R for both accelerating tubes and posts were collected during five scheduled accelerator maintenance tank openings during 2013 and 2014. Components with measured ΔR/R>±2.5% were considered faulty and put through a detailed examination, with faults categorized. In total, thirty four unique fault categories were identified and most would not be identifiable without the new technique described. The most common failure mode was permanent and irreversible insulator current leakage that developed after being exposed to the ambient environment. As a result of efficient in situ troubleshooting and fault-elimination techniques, the maximum values of |ΔR/R| are kept below 2.5% at the conclusion of maintenance procedures. The acceptance margin could be narrowed even further by a factor of 2.5 by increasing the test voltage from 40 V up to 100 V. Based on experience over the last two years, resistor and

  14. A novel method for real-time skin impedance measurement during radiofrequency skin tightening treatments.

    Science.gov (United States)

    Harth, Yoram; Lischinsky, Daniel

    2011-03-01

    The thermal effects of monopolar and bipolar radiofrequency (RF) have been proven to be beneficial in skin tightening. Nevertheless, these effects were frequently partial or unpredictable because of the uncontrolled nature of monopolar or unipolar RF and the superficial nature of energy flow for bipolar or tripolar configurations. One of the hypotheses for lack or predictability of efficacy of the first-generation RF therapy skin tightening systems is lack of adaptation of delivered power to differences in individual skin impedance. A novel multisource phase-controlled system was used (1 MHz, power range 0-65 W) for treatment and real-time skin impedance measurements in 24 patients (EndyMed PRO™; EndyMed, Cesarea, Israel). This system allows continuous real-time measurement of skin impedance delivering constant energy to the patient skin independent of changes in its impedance. More than 6000 unique skin impedance measurements on 22 patients showed an average session impedance range was 215-584 Ohm with an average of 369 Ohm (standard deviation of 49 Ohm). Analyzing individual pulses (total of 600 readings) showed a significant decrease in impedance during the pulse. These findings validate the expected differences in skin impedance between individual patients and in the same patients during the treatment pulse. Clinical study on 30 patients with facial skin aging using the device has shown high predictability of efficacy (86.7% of patients had good results or better at 3 months' follow-up [decrease of 2 or more grades in Fitzpatrick's wrinkle scale]). The real-time customization of energy according to skin impedance allows a significantly more accurate and safe method of nonablative skin tightening with more consistent and predictable results. © 2011 Wiley Periodicals, Inc.

  15. Estimativa da composição corporal e análise de concordância entre analisadores de impedância bioelétrica bipolar e tetrapolar Body composition estimation and agreement analysis between bipolar and tetrapolar bioelectrical impedance analyzers

    Directory of Open Access Journals (Sweden)

    José Claudio Jambassi Filho

    2010-02-01

    Full Text Available O objetivo deste estudo foi analisar as estimativas da composição corporal e a concordância das medidas produzidas por meio de dois diferentes analisadores de impedância bioelétrica em homens adultos jovens. Vinte e dois sujeitos (23,6 ± 2,9 anos; 73 ± 6,8kg; 177,6 ± 6,0cm; 23,1 ± 1,9kg/m², aparentemente saudáveis, foram submetidos a medidas de impedância bioelétrica por meio dos analisadores tetrapolar de corpo inteiro (TCI, Biodynamic Body Composition Analyser, modelo 310 e bipolar para membros superiores (BMS, Omron tm, modelo HBF-306BL após jejum de 12h. Estimativas da gordura corporal relativa (%GC, massa livre de gordura (MLG e massa gorda (MG foram estabelecidas a partir das informações fornecidas pelos dois equipamentos. Nenhuma diferença estatisticamente significante foi verificada para %GC (10,9 ± 4,3 vs. 10,0 ± 4,2%; P = 0,09, MG (8,1 ± 3,5 vs. 7,4 ± 3,5kg; P = 0,10 e MLG (64,9 ± 5,2 vs. 65,5 ± 4,9kg; P = 0,09 entre TCI e BMS, respectivamente. Correlações positivas e significantes (P The aim of this study was to analyze the body composition estimation and agreement of the measurements produced from two bioelectrical impedance analysers in young adult men. Twenty-two apparently healthy subjects (23.6 ± 2.9 yrs; 73.0 ± 6.8 kg; 177.6 ± 6.0 cm; 23.1 ± 1.9 kg/m², were submitted to bioelectrical impedance measurements by tetra-polar whole body (TWB, Biodynamic Body Composition Analyser, model 310 and bipolar for upper body (BUB, OMRON TM, model HBF-306BL after 12 h fast. Relative body fat (%BF, lean body mass (LBM and fat mass (FM estimation were established from information supplied by two analysers. No significant difference was verified for %BF (10.9 ±4.3 vs. 10.0 ±4.2%; P = 0.09, FM (8.1 ±3.5 vs. 7.4 ±3.5 kg; P = 0.10 or LBM (64.9 ±5.2 vs. 65.5 ±4.9 kg; P = 0.09 between TWB and BUB, respectively. Positive significant correlations (P < 0.001 were found between both analysers for LBM (r = 0.948, FM (r

  16. Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanlin [Department of Thermal Energy Engineering, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing, 102249 (China); Wang, Mi [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (China); Yao, Jun [School of Energy Research, Xiamen University, Xiamen 361005 (China)

    2014-04-11

    Electrical impedance tomography (EIT) is one of the process tomography techniques to provide an on-line non-invasive imaging for multiphase flow measurement. With EIT measurements, the images of impedance real part, impedance imaginary part, phase angle, and magnitude can be obtained. However, most of the applications of EIT in the process industries rely on the conductivity difference between two phases in fluids to obtain the concentration profiles. It is not common to use the imaginary part or phase angle due to the dominant change in conductivity or complication in the use of other impedance information. In a solid-liquid two phases system involving nano- or submicro-particles, characterisation of particles (e.g. particle size and concentration) have to rely on the measurement of impedance phase angle or imaginary part. Particles in a solution usually have an electrical double layer associated with their surfaces and can form an induced electrical dipole moment due to the polarization of the electrical double layer under the influence of an alternating electric field. Similar to EIT, electrical impedance spectroscopy (EIS) measurement can record the electrical impedance data, including impedance real part, imaginary part and phase angle (θ), which are caused by the polarization of the electrical double layer. These impedance data are related to the particle characteristics e.g. particle size, particle and ionic concentrations in the aqueous medium, therefore EIS method provides a capability for characterising the particles in suspensions. Electrical impedance tomography based on EIS measurement or namely, electrical impedance tomography spectroscopy (EITS) could image the spatial distribution of particle characteristics. In this paper, a new method, including test set-up and data analysis, for characterisation of particles in suspensions are developed through the experimental approach. The experimental results on tomographic imaging of colloidal particles

  17. Electrical impedance tomography methods for miniaturised 3D systems

    DEFF Research Database (Denmark)

    Canali, Chiara; Aristovich, K.; Ceccarelli, Lorenzo

    2016-01-01

    chambers (Ø 10 mm), each having eight gold plated needle electrodes vertically integrated along the chamber perimeter. As first method, the adjacent electrode configuration was tested solving the computationally simple back-projection algorithm using Comsol Multiphysics in time-difference EIT (t...

  18. Bioelectric Applications for Treatment of Melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Beebe, Stephen J., E-mail: sbeebe@odu.edu; Schoenbach, Karl H.; Heller, Richard [Frank Reidy Research Center for Bioelectrics/Old Dominion University 4211 Monarch Way, Suite 300, Norfolk, Virginia 23508 (United States)

    2010-09-27

    Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.

  19. Bioelectric Applications for Treatment of Melanoma

    Directory of Open Access Journals (Sweden)

    Richard Heller

    2010-09-01

    Full Text Available Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs. EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.

  20. Bioelectric Applications for Treatment of Melanoma

    International Nuclear Information System (INIS)

    Beebe, Stephen J.; Schoenbach, Karl H.; Heller, Richard

    2010-01-01

    Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma

  1. Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

    Directory of Open Access Journals (Sweden)

    Mohamed-Rachid Boulassel

    2015-11-01

    Full Text Available Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001. The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41–0.62, indicating moderate reliability between the methods. The degree of agreement between methods ranged from -85.5 to 24.3 with an estimated bias of -30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis.

  2. Experimental facility and void fraction calibration methods for impedance probes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fernando L. de; Rocha, Marcelo S., E-mail: floliveira@ipen.br, E-mail: msrocha@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    An experimental facility was designed and constructed with aims of to calibrate a capacitance probe for gas-liquid flow void fraction measurements. The facility is composed of a metallic hack with a vertical 2,300 mm high glass tube with 38 mm ID with stagnant water and compressed air bubbling system simulating the gas phase (vapor). At the lower part, a mixing section with a porous media element releases the air bubbles into the water, and the compressed air flow is measured by two calibrated rotameters. At the upper part a stagnant water tank separates the liquid and gas. Two pressure taps are located near the lower and upper sides of the glass tube for pressure difference measurement. The pressure difference is used for low void fraction values (0-15%) calibration methods, as described in the work. Two electrically controlled quick closing valves are installed between the porous media element and the upward separation tank for high void fraction values measurement (15-50%) used to calibrate the capacitance probe. The experimental facility design, construction, capacitance probe calibration methods and results, as well as flow pattern visualization, are presented. Finally, the capacitance probe will be installed on a natural circulation circuit mounted at the Nuclear Engineering Center (CEN/IPEN/CNEN-SP) for measurement of the instantaneous bulk void. Instantaneous signals generated by the capacitance probe will allow the determination of natural circulation loop global energy balance. (author)

  3. Experimental facility and void fraction calibration methods for impedance probes

    International Nuclear Information System (INIS)

    Oliveira, Fernando L. de; Rocha, Marcelo S.

    2013-01-01

    An experimental facility was designed and constructed with aims of to calibrate a capacitance probe for gas-liquid flow void fraction measurements. The facility is composed of a metallic hack with a vertical 2,300 mm high glass tube with 38 mm ID with stagnant water and compressed air bubbling system simulating the gas phase (vapor). At the lower part, a mixing section with a porous media element releases the air bubbles into the water, and the compressed air flow is measured by two calibrated rotameters. At the upper part a stagnant water tank separates the liquid and gas. Two pressure taps are located near the lower and upper sides of the glass tube for pressure difference measurement. The pressure difference is used for low void fraction values (0-15%) calibration methods, as described in the work. Two electrically controlled quick closing valves are installed between the porous media element and the upward separation tank for high void fraction values measurement (15-50%) used to calibrate the capacitance probe. The experimental facility design, construction, capacitance probe calibration methods and results, as well as flow pattern visualization, are presented. Finally, the capacitance probe will be installed on a natural circulation circuit mounted at the Nuclear Engineering Center (CEN/IPEN/CNEN-SP) for measurement of the instantaneous bulk void. Instantaneous signals generated by the capacitance probe will allow the determination of natural circulation loop global energy balance. (author)

  4. New equivalent-electrical circuit model and a practical measurement method for human body impedance.

    Science.gov (United States)

    Chinen, Koyu; Kinjo, Ichiko; Zamami, Aki; Irei, Kotoyo; Nagayama, Kanako

    2015-01-01

    Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

  5. Impedance ratio method for urine conductivity-invariant estimation of bladder volume

    Directory of Open Access Journals (Sweden)

    Thomas Schlebusch

    2014-09-01

    Full Text Available Non-invasive estimation of bladder volume could help patients with impaired bladder volume sensation to determine the right moment for catheterisation. Continuous, non-invasive impedance measurement is a promising technology in this scenario, although influences of body posture and unknown urine conductivity limit wide clinical use today. We studied impedance changes related to bladder volume by simulation, in-vitro and in-vivo measurements with pigs. In this work, we present a method to reduce the influence of urine conductivity to cystovolumetry and bring bioimpedance cystovolumetry closer to a clinical application.

  6. Method, system and computer-readable media for measuring impedance of an energy storage device

    Science.gov (United States)

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.; Motloch, Chester G.

    2016-01-26

    Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. A time profile of this sampled signal has a duration that is a few periods of the lowest frequency. A voltage response of the battery, average deleted, is an impedance of the battery in a time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time profile by rectifying relative to sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.

  7. The New Method of the PV Panels Fault Detection Using Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Symonowicz, Joanna Karolina; Riedel, Nicholas; Thorsteinsson, Sune

    The aim of our project is to develop a new method for photovoltaic (PV) panel fault detection based on analyzing impedance spectroscopy (IS) spectra. Although this technique was successful in assessing the state of degradation of fuel cells and batteries, it has never been applied to PV cells...

  8. Application of the Method of Auxiliary Sources for the Analysis of Electromagnetic Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  9. Method and device for bio-impedance measurement with hard-tissue applications

    International Nuclear Information System (INIS)

    Guimerà, A; Calderón, E; Los, P; Christie, A M

    2008-01-01

    Bio-impedance measurements can be used to detect and monitor several properties of living hard-tissues, some of which include bone mineral density, bone fracture healing or dental caries detection. In this paper a simple method and hardware architecture for hard tissue bio-impedance measurement is proposed. The key design aspects of such architecture are discussed and a commercial handheld ac impedance device is presented that is fully certified to international medical standards. It includes a 4-channel multiplexer and is capable of measuring impedances from 10 kΩ to 10 MΩ across a frequency range of 100 Hz to 100 kHz with a maximum error of 5%. The device incorporates several user interface methods and a Bluetooth link for bi-directional wireless data transfer. Low-power design techniques have been implemented, ensuring the device exceeds 8 h of continuous use. Finally, bench test results using dummy cells consisting of parallel connected resistors and capacitors, from 10 kΩ to 10 MΩ and from 20 pF to 100 pF, are discussed

  10. Method and device for bio-impedance measurement with hard-tissue applications.

    Science.gov (United States)

    Guimerà, A; Calderón, E; Los, P; Christie, A M

    2008-06-01

    Bio-impedance measurements can be used to detect and monitor several properties of living hard-tissues, some of which include bone mineral density, bone fracture healing or dental caries detection. In this paper a simple method and hardware architecture for hard tissue bio-impedance measurement is proposed. The key design aspects of such architecture are discussed and a commercial handheld ac impedance device is presented that is fully certified to international medical standards. It includes a 4-channel multiplexer and is capable of measuring impedances from 10 kOmega to 10 MOmega across a frequency range of 100 Hz to 100 kHz with a maximum error of 5%. The device incorporates several user interface methods and a Bluetooth link for bi-directional wireless data transfer. Low-power design techniques have been implemented, ensuring the device exceeds 8 h of continuous use. Finally, bench test results using dummy cells consisting of parallel connected resistors and capacitors, from 10 kOmega to 10 MOmega and from 20 pF to 100 pF, are discussed.

  11. Impedance measurement of irradiated potatoes: a method to identify radiation processing

    International Nuclear Information System (INIS)

    Mastro, N.L. del; Villavicencio, A.L.C.H.

    1992-01-01

    The potato is firmly established in many parts of the world as a major staple food. Then, radiation processing of potato is approved in many countries for sprouting inhibition and extension of shelf life in a dose range from about 0.01 to 0.15 kGy of 60 Co. The use of electrical conductance methods for the detection of Salmonella, some virus or the action of herbicides on plant has been reported and differences have been observed between instruments in respect of the magnitude of conductance change or rates of change in conductance response. A reliable technique to identify potatoes or other food products has not been established so far, though several methods have been reported. Electrical impedance might thus serve for characterization of unirradiated and irradiated tissues and cells. In this work, potato tubers from an European variety, named Bintje, grown in Sao Paulo State were employed. Potatoes were punctured with steel electrodes and impedance measured at different frequencies (1 k Hz-100 k Hz) by passing 3-5 m A alternating current through it. The impedance ratio of 50 k Hz/5 k Hz calculated from ten replicate samples decreases with the increment of the dose when doses of O 0.75 and 0.15 kGy from a Gamma Cell 220 were utilized. The impedance measurement were slightly affected by the place of puncture. (author)

  12. Electrical impedance spectroscopy and diagnosis of tendinitis

    International Nuclear Information System (INIS)

    Yoon, Kisung; Lee, Kyeong Woo; Kim, Sang Beom; Lee, Jong Hwa; Han, Tai Ryoon; Jung, Dong Keun; Roh, Mee Sook

    2010-01-01

    There have been a number of studies that investigate the usefulness of bioelectric signals in diagnoses and treatment in the medical field. Tendinitis is a musculoskeletal disorder with a very high rate of occurrence. This study attempts to examine whether electrical impedance spectroscopy (EIS) can detect pathological changes in a tendon and find the exact location of the lesion. Experimental tendinitis was induced by injecting collagenase into one side of the patellar tendons in rabbits, while the other side was used as the control. After measuring the impedance in the tendinitis and intact tendon tissue, the dissipation factor was computed. The real component of impedance and the dissipation factor turned out to be lower in tendinitis than in intact tissues. Moreover, the tendinitis dissipation factor spectrum showed a clear difference from that of the intact tendon, indicating its usefulness as a tool for detecting the location of the lesion. Pathologic findings from the tissues that were obtained after measuring the impedance confirmed the presence of characteristics of tendinitis. In conclusion, EIS is a useful method for diagnosing tendinitis and detecting the lesion location in invasive treatment

  13. Bioelectrical Perchlorate Remediation

    Science.gov (United States)

    Thrash, C.; Achenbach, L. A.; Coates, J. D.

    2007-12-01

    Several bioreactor designs are currently available for the ex-situ biological attenuation of perchlorate- contaminated waters and recently, some of these reactor designs were conditionally approved by the California Department of Health Services for application in the treatment of perchlorate contaminated drinking water. However, all of these systems are dependent on the continual addition of a chemical electron donor to sustain microbial activity and are always subject to biofouling and downstream water quality issues. In addition, residual labile electron donor in the reactor effluent can stimulate microbial growth in water distribution systems and contribute to the formation of potentially toxic trihalomethanes during disinfection by chlorination. As part of our ongoing studies into microbial perchlorate reduction we investigated the ability of dissimilatory perchlorate reducing bacteria (DPRB) to metabolize perchlorate using a negatively charged electrode (cathode) in the working chamber of a bioelectrical reactor (BER) as the primary electron donor. In this instance the DPRB use the electrons on the electrode surface either directly or indirectly in the form of electrolytically produced H2 as a source of reducing equivalents for nitrate and perchlorate reduction. As part of this investigation our fed-batch studies showed that DPRB could use electrons from a graphite cathode poised at -500mV (vs. Ag/AgCl) for the reduction of perchlorate and nitrate. We isolated a novel organism, Dechlorospirillum strain VDY, from the cathode surface after 70 days operation which readily reduced 100 mg.L-1 perchlorate in a mediatorless batch bioelectrical reactor (BER) in 6 days. Continuous up-flow BERs (UFBERs) seeded with active cultures of strain VDY continuously treated waters containing 100 mg.L-1 perchlorate with almost 100% efficiency throughout their operation achieving a non-optimized volumetric loading of 60 mg.L-1 reactor volume.day-1. The same UFBERs also treated

  14. A study on calculation method for mechanical impedance of air spring

    International Nuclear Information System (INIS)

    Changgeng, Shuai; Penghui, Li; Rustighi, Emiliano

    2016-01-01

    This paper proposes an approximate analytic method of obtaining the mechanical impedance of air spring. The sound pressure distribution in cylindrical air spring is calculated based on the linear air wave theory. The influences of different boundary conditions on the acoustic pressure field distribution in cylindrical air spring are analysed. A 1-order ordinary differential matrix equation for the state vector of revolutionary shells under internal pressure is derived based on the non-moment theory of elastic thin shell. Referring to the transfer matrix method, a kind of expanded homogeneous capacity high precision integration method is introduced to solve the non-homogeneous matrix differential equation. Combined the solved stress field of shell with the calculated sound pressure field in air spring under the displacement harmonic excitation, the approximate analytical expression of the input and transfer mechanical impedance for the air spring can be achieved. The numerical simulation with the Comsol Multiphysics software verifies the correctness of theoretical analysis result. (paper)

  15. Voltage Based Detection Method for High Impedance Fault in a Distribution System

    Science.gov (United States)

    Thomas, Mini Shaji; Bhaskar, Namrata; Prakash, Anupama

    2016-09-01

    High-impedance faults (HIFs) on distribution feeders cannot be detected by conventional protection schemes, as HIFs are characterized by their low fault current level and waveform distortion due to the nonlinearity of the ground return path. This paper proposes a method to identify the HIFs in distribution system and isolate the faulty section, to reduce downtime. This method is based on voltage measurements along the distribution feeder and utilizes the sequence components of the voltages. Three models of high impedance faults have been considered and source side and load side breaking of the conductor have been studied in this work to capture a wide range of scenarios. The effect of neutral grounding of the source side transformer is also accounted in this study. The results show that the algorithm detects the HIFs accurately and rapidly. Thus, the faulty section can be isolated and service can be restored to the rest of the consumers.

  16. Determination of abdominal fat thickness using dual electrode separation in the focused impedance method (FIM)

    International Nuclear Information System (INIS)

    Surovy, Nusrat Jahan; Billah, Md Masum; Haowlader, Salahuddin; Al-Quaderi, Golam Dastegir; Rabbani, K Siddique-e

    2012-01-01

    Subcutaneous fat layer thickness in the abdomen is a risk indicator of several diseases and disorders like diabetes and heart problems and could be used as a measure of fitness. Skinfold measurement using mechanical calipers is simple but prone to error. Ultrasound scanning techniques are yet to be established as accurate methods for this purpose. magnetic resonance imaging (MRI) and computed tomography (CT) scans can provide the answer but are expensive and not available widely. Some initiatives were made earlier to use electrical impedance to this end, but had inadequacies. In the first part of this paper, a 4-electrode focused impedance method (FIM) with different electrode separations has been studied for its possible use in the determination of abdominal fat thickness in a localized region. For this, a saline phantom was designed to provide different electrode separations and different layers of resistive materials adjacent to the electrodes. The background saline simulated the internal organs having low impedance while the resistive layers simulated the subcutaneous fat. The plot of the measured impedance with electrode separation had different ‘slopes’ for different thicknesses of resistive layers, which offered a method to obtain an unknown thickness of subcutaneous fat layer. In the second part, measurements were performed on seven human subjects using two electrode separations. Fat layer thickness was measured using mechanical calipers. A plot of the above ‘slope’ against fat thickness could be fitted using a straight line with an R 2 of 0.93. Then this could be used as a calibration curve for the determination of unknown fat thickness. Further work using more accurate CT and MRI measurements would give a better calibration curve for practical use of this non-invasive and low-cost technique in abdominal fat thickness measurement. (paper)

  17. A new lithium-ion battery internal temperature on-line estimate method based on electrochemical impedance spectroscopy measurement

    Science.gov (United States)

    Zhu, J. G.; Sun, Z. C.; Wei, X. Z.; Dai, H. F.

    2015-01-01

    The power battery thermal management problem in EV (electric vehicle) and HEV (hybrid electric vehicle) has been widely discussed, and EIS (electrochemical impedance spectroscopy) is an effective experimental method to test and estimate the status of the battery. Firstly, an electrochemical-based impedance matrix analysis for lithium-ion battery is developed to describe the impedance response of electrochemical impedance spectroscopy. Then a method, based on electrochemical impedance spectroscopy measurement, has been proposed to estimate the internal temperature of power lithium-ion battery by analyzing the phase shift and magnitude of impedance at different ambient temperatures. Respectively, the SoC (state of charge) and temperature have different effects on the impedance characteristics of battery at various frequency ranges in the electrochemical impedance spectroscopy experimental study. Also the impedance spectrum affected by SoH (state of health) is discussed in the paper preliminary. Therefore, the excitation frequency selected to estimate the inner temperature is in the frequency range which is significantly influenced by temperature without the SoC and SoH. The intrinsic relationship between the phase shift and temperature is established under the chosen excitation frequency. And the magnitude of impedance related to temperature is studied in the paper. In practical applications, through obtaining the phase shift and magnitude of impedance, the inner temperature estimation could be achieved. Then the verification experiments are conduced to validate the estimate method. Finally, an estimate strategy and an on-line estimation system implementation scheme utilizing battery management system are presented to describe the engineering value.

  18. Evaluation method for corrosion level of rebar in RC with electrical impedance measurement

    Science.gov (United States)

    Sasamoto, Akira

    2018-04-01

    The author reported that the impedance measurement using the 4-terminal method on the RC surface for diagnosing corrosion of internal rebar. The difference between the maximum value at 0.01 Hz and the minimum value around 10 Hz indicates the corrosion level of rebar in that report. This is successive report on a signal processing method for estimating the corrosion level by the measured impedance data to obtain more high accuracy. In the dielectric, a graph of frequency and dielectric constant (Cole-Cole plot diagram by KS Cole and RH Cole article of 1941) draws a shape of circle if the dielectric is independent of frequency but it draws a shape of ellipse in reality due to frequency dependency. Havriliak and Negami have also presented Havriliak-Negami model which introduced parameter into dielectric constant equation which deforms Cole-Cole plot diagram and showed that acquired dielectric data of polymer materials fit to this model with proper parameters. In this report, we first consider electric model connected with resistance and capacitance as a rough model of RC concrete. If the capacitance in this model circuit has some loss of dielectric, it is stated that graph in impedance plot is expected to take as similar deformation in the dielectric Cole-Cole plot. Then a numerical optimization computer code for obtaining parameters in the Cole-Cole plot diagram and Havriliak-Negami model is constructed, and the correlation between the deformation parameter of each model and corrosion is shown by this code. These results are feasibility study for diagnosis of corrosion level of rebar by associated parameters to a shape of impedance graph.

  19. INVESTIGATION OF CEMENT CONCRETE CONGLOMERATE SOLIDIFICATION PROCESS BY IMPEDANCE SPECTROSCOPY METHOD

    Directory of Open Access Journals (Sweden)

    S. N. Bandarenka

    2015-01-01

    Full Text Available One of the most prospective directions in preservation  and increase of service live of  road pavements is a construction of  automobile roads with cement concrete surface. Modern tendencies for provision of road construction quality presuppose a necessity to control processes of solidification and subsequent destruction of the material while forming and using cement concrete conglomerate being considered as a basic element of the road surface.  Multiyear practical experience of  automobile road operation using cement concrete pavements reveals an importance for monitoring  such processes as formation and destruction of cement concrete materials. An impedance spectroscopy method has been tried out and proposed as a tool for solution of the given problem.Experimental samples of cement concrete have been prepared for execution of tests, graded silica sand and granite chippings with particle size from 0.63 to 2.5 mm have been used as a fine aggregate in the samples. Dependencies of resistance (impedance on AC-current frequency  have been studied for samples of various nature and granulometric composition. The Gamry  G300 potentiostat has been used for measurement of complex impedance value. A spectrum analysis and calculation of equivalent circuit parameters calculation have been carried out while using EIS Spectrum Analyzer program.Comparison of impedance spectra for the prepared cement concrete samples have made it possible to reveal tendencies in changing spectrum parameters during solidification and subsequent contact with moisture in respect of every type of the sample. An equivalent electrical circuit has been developed that  characterizes physical and chemical processes which are accompanied by charge transfer in cement concrete conglomerate. The paper demonstrates a possibility to use an impedance spectroscopy for solution of a number of actual problems in the field of cement concrete technology problems. Particularly, the problems

  20. Abdominal fat thickness measurement using Focused Impedance Method (FIM) - phantom study

    Science.gov (United States)

    Haowlader, Salahuddin; Baig, Tanveer Noor; Siddique-e Rabbani, K.

    2010-04-01

    Abdominal fat thickness is a risk indicator of heart diseases, diabetes, etc., and its measurement is therefore important from the point of view of preventive care. Tetrapolar electrical impedance measurements (TPIM) could offer a simple and low cost alternative for such measurement compared to conventional techniques using CT scan and MRI, and has been tried by different groups. Focused Impedance Method (FIM) appears attractive as it can give localised information. An intuitive physical model was developed and experimental work was performed on a phantom designed to simulate abdominal subcutaneous fat layer in a body. TPIM measurements were performed with varying electrode separations. For small separations of current and potential electrodes, the measured impedance changed little, but started to decrease sharply beyond a certain separation, eventually diminishing gradually to negligible values. The finding could be explained using the intuitive physical model and gives an important practical information. TPIM and FIM may be useful for measurement of SFL thickness only if the electrode separations are within a certain specific range, and will fail to give reliable results if beyond this range. Further work, both analytical and experimental, are needed to establish this technique on a sound footing.

  1. Development of AC impedance methods for evaluating corroding metal surfaces and coatings

    Science.gov (United States)

    Knockemus, Ward

    1986-01-01

    In an effort to investigate metal surface corrosion and the breakdown of metal protective coatings the AC Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The model 368-1 AC Impedance Measurement System recently acquired by the MSFC Corrosion Research Branch was used to monitor changing properties of coated aluminum disks immersed in 3.5% NaCl buffered at ph 5.5 over three to four weeks. The DC polarization resistance runs were performed on the same samples. The corrosion system can be represented by an electronic analog called an equivalent circuit that consists of transistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacities that can be assigned in the equivalent circuit following a least squares analysis of the data describe changes that occur on the corroding metal surface and in the protective coating. A suitable equivalent circuit was determined that predicts the correct Bode phase and magnitude for the experimental sample. The DC corrosion current density data are related to equivalent circuit element parameters.

  2. Resistive wall impedance of the LHC beam screen without slots calculated by boundary element method

    CERN Document Server

    Tsutsui, H

    2002-01-01

    In order to calculate the resistive wall impedance of the LHC beam screen without slots, the Boundary Element Method (BEM) is used. The result at 1 GHz is Re(ZL/L) = 6.689×10−3 Ω/m, Re(Zx/L) = 1.251 Ω/m2, Re(Zy/L) = 1.776 Ω/m2, andRe(2Z0,2 cos/kL) = −0.525 Ω/m2, assuming σ = 5.8 × 109 /Ωm.

  3. Sugarcane bio ethanol and bioelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Luiz Augusto Horta; Leal, Manoel Regis Lima Verde

    2012-07-01

    This chapter approaches the Brazilian sugar cane production and processing model, sugarcane processing, sugarcane reception, sugarcane preparation and juice extraction, juice treatment, fermentation, distillation, sector efficiencies and future improvement - 2007, 2015 and 2025, present situation (considering the 2007/2008 harvesting season), prospective values for 2015 and for 2025, bioelectricity generation, straw recovery, bagasse availability, energy balance, present situation, perspective for improvements in the GHG mitigation potential, bio ethanol production chain - from field to tank, and surplus electricity generation.

  4. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly; Bioimpedancia eletrica e gordura visceral: uma comparacao com a tomografia computadorizada em adultos e idosos

    Energy Technology Data Exchange (ETDEWEB)

    Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)

    2013-05-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  5. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly; Bioimpedancia eletrica e gordura visceral: uma comparacao com a tomografia computadorizada em adultos e idosos

    Energy Technology Data Exchange (ETDEWEB)

    Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)

    2013-05-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  6. A novel broadband impedance method for detection of cell-derived microparticles.

    Science.gov (United States)

    Lvovich, Vadim; Srikanthan, Sowmya; Silverstein, Roy L

    2010-10-15

    A novel label-free method is presented to detect and quantify cell-derived microparticles (MPs) by the electrochemical potential-modulated electrochemical impedance spectroscopy (EIS). MPs are present in elevated concentrations during pathological conditions and play a major role in the establishment and pathogenesis of many diseases. Considering this, accurate detection and quantification of MPs is very important in clinical diagnostics and therapeutics. A combination of bulk solution electrokinetic sorting and interfacial impedance responses allows achieving detection limits as low as several MPs per μL. By fitting resulting EIS spectra with an equivalent electrical circuit, the bulk solution electrokinetic and interfacial impedance responses were characterized. In the bulk solution two major relaxations were prominent-β-relaxation in low MHz region due to the MP capacitive membrane bridging, and α-relaxation at ∼10 kHz due to counter ions diffusion. At low frequencies (10-0.1 Hz) at electrochemical potentials exceeding -100 mV, a facile interfacial Faradaic process of oxidation in MPs coupled with diffusion and non-Faradaic double layer charging dominate, probably due to oxidation of phospholipids and/or proteins on the MP surface and MP lysis. Buffer influence on the MP detection demonstrated that a relatively low conductivity Tyrode's buffer background solution is preferential for the MP electrokinetic separation and characterization. This study also demonstrated that standard laboratory methods such as flow cytometry underestimate MP concentrations, especially those with smaller average sizes, by as much as a factor of 2-40. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Soil-structure interaction - a general method to calculate soil impedance

    International Nuclear Information System (INIS)

    Farvacque, M.; Gantenbein, F.

    1983-01-01

    A correct analysis of the seismic response of nuclear power plant buildings needs to take into account the soil structure interaction. The most classical and simple method consists in characterizing the soil by a stiffness and a damping function for each component of the translation and rotation of the foundation. In a more exact way an impedance function of the frequency may be introduced. Literature provides data to estimate these coefficients for simple soil and foundation configurations and using linear hypothesis. This paper presents a general method to calculate soil impedances which is based on the computation of the impulsive response of the soil using an axisymmetric 2D finite element Code (INCA). The Fourier transform of this response is made in the time interval before the return of the reflected waves on the boundaries of the F.E. domain. This procedure which limits the perturbing effects of the reflections is improved by introducing absorbing boundary elements. A parametric study for homogeneous and layered soils has been carried out using this method. (orig.)

  8. Improving the Stability and Accuracy of Power Hardware-in-the-Loop Simulation Using Virtual Impedance Method

    Directory of Open Access Journals (Sweden)

    Xiaoming Zha

    2016-11-01

    Full Text Available Power hardware-in-the-loop (PHIL systems are advanced, real-time platforms for combined software and hardware testing. Two paramount issues in PHIL simulations are the closed-loop stability and simulation accuracy. This paper presents a virtual impedance (VI method for PHIL simulations that improves the simulation’s stability and accuracy. Through the establishment of an impedance model for a PHIL simulation circuit, which is composed of a voltage-source converter and a simple network, the stability and accuracy of the PHIL system are analyzed. Then, the proposed VI method is implemented in a digital real-time simulator and used to correct the combined impedance in the impedance model, achieving higher stability and accuracy of the results. The validity of the VI method is verified through the PHIL simulation of two typical PHIL examples.

  9. Evaluation of different methods for measuring the impedance of Lithium-ion batteries during ageing

    DEFF Research Database (Denmark)

    Stroe, Daniel Loan; Swierczynski, Maciej Jozef; Stroe, Ana-Irina

    2015-01-01

    The impedance represents one of the most important performance parameters of the Lithium-ion batteries since it used for power capability calculations, battery pack and system design, cooling system design and also for state-of-health estimation. In the literature, different approaches...... are presented for measuring the impedance of Lithium-ion batteries and electrochemical impedance spectroscopy and dc current pulses are the most used ones; each of these approaches has its own advantages and drawbacks. The goal of this paper is to investigate which of the most encountered impedance measurement...... approaches is the most suitable for measuring the impedance of Lithium-ion batteries during ageing....

  10. New method of silicon photovoltaic panel fault detection using impedance spectroscopy

    DEFF Research Database (Denmark)

    Symonowicz, Joanna Karolina; Riedel, Nicholas; Thorsteinsson, Sune

    2017-01-01

    The aim of our project is to develop a new method for photovoltaic (PV) panel fault detection based on analysing its impedance spectra (IS). Although this technique was successful in assessing the state of degradation of fuel cells and batteries [1, 2], it has never been applied to PV cells...... on a wide scale. In this paper, we show that, unlike current-voltage (I-V) tests, the IS method is capable of early detection of changes in PV panel parameters due to microcracks and potential-induced degradation (PID). Although our measurements are only successful under dark conditions, the results...... are similar for both laboratory environment and for outdoor tests in various weather conditions. A fully developed IS technique, accounting for all kinds of most common PV panel degradation types, would surpass the existing PV fault detection methods then it comes to cost and accuracy [3,4]....

  11. Hybrid islanding detection method by using grid impedance estimation in parallel-inverters-based microgrid

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

    2014-01-01

    This paper presents a hybrid islanding detection algorithm integrated on the distributed generation unit more close to the point of common coupling of a Microgrid based on parallel inverters where one of them is responsible to control the system. The method is based on resonance excitation under...... parameters, both resistive and inductive parts, from the injected resonance frequency determination. Finally, the inverter will disconnect the microgrid from the faulty grid and reconnect the parallel inverter system to the controllable distributed system in order to ensure high power quality. This paper...... shows that grid impedance variation detection estimation can be an efficient method for islanding detection in microgrid systems. Theoretical analysis and simulation results are presented to validate the proposed method....

  12. Image Reconstruction Based on Homotopy Perturbation Inversion Method for Electrical Impedance Tomography

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2013-01-01

    Full Text Available The image reconstruction for electrical impedance tomography (EIT mathematically is a typed nonlinear ill-posed inverse problem. In this paper, a novel iteration regularization scheme based on the homotopy perturbation technique, namely, homotopy perturbation inversion method, is applied to investigate the EIT image reconstruction problem. To verify the feasibility and effectiveness, simulations of image reconstruction have been performed in terms of considering different locations, sizes, and numbers of the inclusions, as well as robustness to data noise. Numerical results indicate that this method can overcome the numerical instability and is robust to data noise in the EIT image reconstruction. Moreover, compared with the classical Landweber iteration method, our approach improves the convergence rate. The results are promising.

  13. System-on-Chip Integration of a New Electromechanical Impedance Calculation Method for Aircraft Structure Health Monitoring

    OpenAIRE

    Boukabache, Hamza; Escriba, Christophe; Zedek, Sabeha; Medale, Daniel; Rolet, Sebastien; Fourniols, Jean Yves

    2012-01-01

    The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M...

  14. Use of stochastic methods for robust parameter extraction from impedance spectra

    International Nuclear Information System (INIS)

    Bueschel, Paul; Troeltzsch, Uwe; Kanoun, Olfa

    2011-01-01

    The fitting of impedance models to measured data is an essential step in impedance spectroscopy (IS). Due to often complicated, nonlinear models, big number of parameters, large search spaces and presence of noise, an automated determination of the unknown parameters is a challenging task. The stronger the nonlinear behavior of a model, the weaker is the convergence of the corresponding regression and the probability to trap into local minima increases during parameter extraction. For fast measurements or automatic measurement systems these problems became the limiting factors of use. We compared the usability of stochastic algorithms, evolution, simulated annealing and particle filter with the widely used tool LEVM for parameter extraction for IS. The comparison is based on one reference model by J.R. Macdonald and a battery model used with noisy measurement data. The results show different performances of the algorithms for these two problems depending on the search space and the model used for optimization. The obtained results by particle filter were the best for both models. This method delivers the most reliable result for both cases even for the ill posed battery model.

  15. Feature Extraction Method for High Impedance Ground Fault Localization in Radial Power Distribution Networks

    DEFF Research Database (Denmark)

    Jensen, Kåre Jean; Munk, Steen M.; Sørensen, John Aasted

    1998-01-01

    A new approach to the localization of high impedance ground faults in compensated radial power distribution networks is presented. The total size of such networks is often very large and a major part of the monitoring of these is carried out manually. The increasing complexity of industrial...... of three phase voltages and currents. The method consists of a feature extractor, based on a grid description of the feeder by impulse responses, and a neural network for ground fault localization. The emphasis of this paper is the feature extractor, and the detection of the time instance of a ground fault...... processes and communication systems lead to demands for improved monitoring of power distribution networks so that the quality of power delivery can be kept at a controlled level. The ground fault localization method for each feeder in a network is based on the centralized frequency broadband measurement...

  16. Bacteriocidal activity of sanitizers against Enterococcus faecium attached to stainless steel as determined by plate count and impedance methods.

    Science.gov (United States)

    Andrade, N J; Bridgeman, T A; Zottola, E A

    1998-07-01

    Enterococcus faecium attached to stainless steel chips (100 mm2) was treated with the following sanitizers: sodium hypochlorite, peracetic acid (PA), peracetic acid plus an organic acid (PAS), quaternary ammonium, organic acid, and anionic acid. The effectiveness of sanitizer solutions on planktonic cells (not attached) was evaluated by the Association of Official Analytical Chemists (AOAC) suspension test. The number of attached cells was determined by impedance measurement and plate count method after vortexing. The decimal reduction (DR) in numbers of the E. faecium population was determined for the three methods and was analyzed by analysis of variance (P plate count method after vortexing, and impedance measurement, respectively. Plate count and impedance methods showed a difference (P measurement was the best method to measure adherent cells. Impedance measurement required the development of a quadratic regression. The equation developed from 82 samples is as follows: log CFU/chip = 0.2385T2-0.96T + 9.35, r2 = 0.92, P plate count method after vortexing. These data suggest that impedance measurement is the method of choice when evaluating the number of bacterial cells adhered to a surface.

  17. Registration of T-2 mycotoxin with total internal reflection ellipsometry and QCM impedance methods.

    Science.gov (United States)

    Nabok, A V; Tsargorodskaya, A; Holloway, A; Starodub, N F; Gojster, O

    2007-01-15

    A sensitive optical method of total internal reflection ellipsometry (TIRE) in conjunction with immune assay approach was exploited for the registration of T-2 mycotoxin in a wide range of concentrations from 100 microg/ml down to 0.15 ng/ml. Association constants of 1.4x10(6) and 1.9x10(7)mol(-1)s for poly- and monoclonal T-2 antibodies, respectively, were evaluated from TIRE kinetic measurements. According to TIRE data fitting, binding of T-2 molecules to antibodies (at saturation) has resulted in the increase in adsorbed layer thickness of 4-5 nm. The QCM impedance measurements data showed anomalously large mass increase and film softening, most likely, due to the binding of large T-2 aggregates to antibodies.

  18. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    Science.gov (United States)

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Multi-phase flow monitoring with electrical impedance tomography using level set based method

    International Nuclear Information System (INIS)

    Liu, Dong; Khambampati, Anil Kumar; Kim, Sin; Kim, Kyung Youn

    2015-01-01

    Highlights: • LSM has been used for shape reconstruction to monitor multi-phase flow using EIT. • Multi-phase level set model for conductivity is represented by two level set functions. • LSM handles topological merging and breaking naturally during evolution process. • To reduce the computational time, a narrowband technique was applied. • Use of narrowband and optimization approach results in efficient and fast method. - Abstract: In this paper, a level set-based reconstruction scheme is applied to multi-phase flow monitoring using electrical impedance tomography (EIT). The proposed scheme involves applying a narrowband level set method to solve the inverse problem of finding the interface between the regions having different conductivity values. The multi-phase level set model for the conductivity distribution inside the domain is represented by two level set functions. The key principle of the level set-based method is to implicitly represent the shape of interface as the zero level set of higher dimensional function and then solve a set of partial differential equations. The level set-based scheme handles topological merging and breaking naturally during the evolution process. It also offers several advantages compared to traditional pixel-based approach. Level set-based method for multi-phase flow is tested with numerical and experimental data. It is found that level set-based method has better reconstruction performance when compared to pixel-based method

  20. Reconstruction of electrical impedance tomography (EIT) images based on the expectation maximum (EM) method.

    Science.gov (United States)

    Wang, Qi; Wang, Huaxiang; Cui, Ziqiang; Yang, Chengyi

    2012-11-01

    Electrical impedance tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. The image reconstruction for EIT is an inverse problem, which is both non-linear and ill-posed. The traditional regularization method cannot avoid introducing negative values in the solution. The negativity of the solution produces artifacts in reconstructed images in presence of noise. A statistical method, namely, the expectation maximization (EM) method, is used to solve the inverse problem for EIT in this paper. The mathematical model of EIT is transformed to the non-negatively constrained likelihood minimization problem. The solution is obtained by the gradient projection-reduced Newton (GPRN) iteration method. This paper also discusses the strategies of choosing parameters. Simulation and experimental results indicate that the reconstructed images with higher quality can be obtained by the EM method, compared with the traditional Tikhonov and conjugate gradient (CG) methods, even with non-negative processing. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Gastric motility measurement and evaluation of functional dyspepsia by a bio-impedance method

    International Nuclear Information System (INIS)

    Li, Zhangyong; Ren, Chaoshi

    2008-01-01

    method of impedance can be a potential tool for the noninvasive assessment of gastric motility under gastrointestinal physiology and pathology conditions

  2. Bioelectric modulation of macrophage polarization

    Science.gov (United States)

    Li, Chunmei; Levin, Michael; Kaplan, David L.

    2016-02-01

    Macrophages play a critical role in regulating wound healing and tissue regeneration by changing their polarization state in response to local microenvironmental stimuli. The native roles of polarized macrophages encompass biomaterials and tissue remodeling needs, yet harnessing or directing the polarization response has been largely absent as a potential strategy to exploit in regenerative medicine to date. Recent data have revealed that specific alteration of cells’ resting potential (Vmem) is a powerful tool to direct proliferation and differentiation in a number of complex tissues, such as limb regeneration, craniofacial patterning and tumorigenesis. In this study, we explored the bioelectric modulation of macrophage polarization by targeting ATP sensitive potassium channels (KATP). Glibenclamide (KATP blocker) and pinacidil (KATP opener) treatment not only affect macrophage polarization, but also influence the phenotype of prepolarized macrophages. Furthermore, modulation of cell membrane electrical properties can fine-tune macrophage plasticity. Glibenclamide decreased the secretion and gene expression of selected M1 markers, while pinacidil augmented M1 markers. More interestingly, glibencalmide promoted macrophage alternative activation by enhancing certain M2 markers during M2 polarization. These findings suggest that control of bioelectric properties of macrophages could offer a promising approach to regulate macrophage phenotype as a useful tool in regenerative medicine.

  3. A new method for electric impedance imaging using an eddy current with a tetrapolar circuit.

    Science.gov (United States)

    Ahsan-Ul-Ambia; Toda, Shogo; Takemae, Tadashi; Kosugi, Yukio; Hongo, Minoru

    2009-02-01

    A new contactless technique for electrical impedance imaging, using an eddy current managed along with the tetrapolar circuit method, is proposed. The eddy current produced by a magnetic field is superimposed on a constant current that is normally used in the tetrapolar circuit method, and thus is used to control the current distribution in the body. By changing the current distribution, a set of voltage differences is measured with a pair of electrodes. This set of voltage differences is used in the image reconstruction of the resistivity distribution. The least square error minimization method is used in the reconstruction algorithm. The principle of this method is explained theoretically. A backprojection algorithm was used to get 2-D images. Based on this principle, a measurement system was developed and model experiments were conducted with a saline-filled phantom. The estimated shape of each model in the reconstructed image was similar to that of the corresponding model. From the results of these experiments, it is confirmed that the proposed method is applicable to the realization of electrical conductivity imaging.

  4. A shape-based quality evaluation and reconstruction method for electrical impedance tomography.

    Science.gov (United States)

    Antink, Christoph Hoog; Pikkemaat, Robert; Malmivuo, Jaakko; Leonhardt, Steffen

    2015-06-01

    Linear methods of reconstruction play an important role in medical electrical impedance tomography (EIT) and there is a wide variety of algorithms based on several assumptions. With the Graz consensus reconstruction algorithm for EIT (GREIT), a novel linear reconstruction algorithm as well as a standardized framework for evaluating and comparing methods of reconstruction were introduced that found widespread acceptance in the community. In this paper, we propose a two-sided extension of this concept by first introducing a novel method of evaluation. Instead of being based on point-shaped resistivity distributions, we use 2759 pairs of real lung shapes for evaluation that were automatically segmented from human CT data. Necessarily, the figures of merit defined in GREIT were adjusted. Second, a linear method of reconstruction that uses orthonormal eigenimages as training data and a tunable desired point spread function are proposed. Using our novel method of evaluation, this approach is compared to the classical point-shaped approach. Results show that most figures of merit improve with the use of eigenimages as training data. Moreover, the possibility of tuning the reconstruction by modifying the desired point spread function is shown. Finally, the reconstruction of real EIT data shows that higher contrasts and fewer artifacts can be achieved in ventilation- and perfusion-related images.

  5. A shape-based quality evaluation and reconstruction method for electrical impedance tomography

    International Nuclear Information System (INIS)

    Antink, Christoph Hoog; Pikkemaat, Robert; Leonhardt, Steffen; Malmivuo, Jaakko

    2015-01-01

    Linear methods of reconstruction play an important role in medical electrical impedance tomography (EIT) and there is a wide variety of algorithms based on several assumptions. With the Graz consensus reconstruction algorithm for EIT (GREIT), a novel linear reconstruction algorithm as well as a standardized framework for evaluating and comparing methods of reconstruction were introduced that found widespread acceptance in the community.In this paper, we propose a two-sided extension of this concept by first introducing a novel method of evaluation. Instead of being based on point-shaped resistivity distributions, we use 2759 pairs of real lung shapes for evaluation that were automatically segmented from human CT data. Necessarily, the figures of merit defined in GREIT were adjusted. Second, a linear method of reconstruction that uses orthonormal eigenimages as training data and a tunable desired point spread function are proposed.Using our novel method of evaluation, this approach is compared to the classical point-shaped approach. Results show that most figures of merit improve with the use of eigenimages as training data. Moreover, the possibility of tuning the reconstruction by modifying the desired point spread function is shown. Finally, the reconstruction of real EIT data shows that higher contrasts and fewer artifacts can be achieved in ventilation- and perfusion-related images. (paper)

  6. A Local Region of Interest Imaging Method for Electrical Impedance Tomography with Internal Electrodes

    Directory of Open Access Journals (Sweden)

    Hyeuknam Kwon

    2013-01-01

    Full Text Available Electrical Impedance Tomography (EIT is a very attractive functional imaging method despite the low sensitivity and resolution. The use of internal electrodes with the conventional reconstruction algorithms was not enough to enhance image resolution and accuracy in the region of interest (ROI. We propose a local ROI imaging method with internal electrodes developed from careful analysis of the sensitivity matrix that is designed to reduce the sensitivity of the voxels outside the local region and optimize the sensitivity of the voxel inside the local region. We perform numerical simulations and physical measurements to demonstrate the localized EIT imaging method. In preliminary results with multiple objects we show the benefits of using an internal electrode and the improved resolution due to the local ROI image reconstruction method. The sensitivity is further increased by allowing the surface electrodes to be unevenly spaced with a higher density of surface electrodes near the ROI. Also, we analyse how much the image quality is improved using several performance parameters for comparison. While these have not yet been studied in depth, it convincingly shows an improvement in local sensitivity in images obtained with an internal electrode in comparison to a standard reconstruction method.

  7. A new method for calculation of low-frequency coupling impedance

    International Nuclear Information System (INIS)

    Kurennoy, S.S.; Stupakov, G.V.

    1993-05-01

    In high-energy proton accelerators and storage rings the bunch length is typically at least a few times larger than the radius of the vacuum chamber. For example, the SSC will have an rms bunch length above 6 cm and a beam-pipe radius below 2 cm. The main concern for beam stability in such a machine is the low-frequency impedance, i.e., the coupling impedance at frequencies wen below the cut-off frequency of the vacuum chamber. In the present paper we develop a new analytical approach for calculation of the low-frequency impedance of axisymmetric structures that allows us to give quick and reliable estimates of contributions to the impedance from various chamber discontinuities. Simple formulae for the longitudinal impedance of some typical discontinuities are obtained

  8. Linearized image reconstruction method for ultrasound modulated electrical impedance tomography based on power density distribution

    International Nuclear Information System (INIS)

    Song, Xizi; Xu, Yanbin; Dong, Feng

    2017-01-01

    Electrical resistance tomography (ERT) is a promising measurement technique with important industrial and clinical applications. However, with limited effective measurements, it suffers from poor spatial resolution due to the ill-posedness of the inverse problem. Recently, there has been an increasing research interest in hybrid imaging techniques, utilizing couplings of physical modalities, because these techniques obtain much more effective measurement information and promise high resolution. Ultrasound modulated electrical impedance tomography (UMEIT) is one of the newly developed hybrid imaging techniques, which combines electric and acoustic modalities. A linearized image reconstruction method based on power density is proposed for UMEIT. The interior data, power density distribution, is adopted to reconstruct the conductivity distribution with the proposed image reconstruction method. At the same time, relating the power density change to the change in conductivity, the Jacobian matrix is employed to make the nonlinear problem into a linear one. The analytic formulation of this Jacobian matrix is derived and its effectiveness is also verified. In addition, different excitation patterns are tested and analyzed, and opposite excitation provides the best performance with the proposed method. Also, multiple power density distributions are combined to implement image reconstruction. Finally, image reconstruction is implemented with the linear back-projection (LBP) algorithm. Compared with ERT, with the proposed image reconstruction method, UMEIT can produce reconstructed images with higher quality and better quantitative evaluation results. (paper)

  9. Progress in electrical impedance imaging of binary media: 1: Analytical and numerical methods

    International Nuclear Information System (INIS)

    Ovacik, Levent; Lin Jentai; Jones, Owen C.

    1998-01-01

    This is the first of two papers summarizing the use of electrical impedance excitation/measurement for producing cross sectional images of the distribution of insulating media imbedded in conducting media. This computed tomographic approach finds the distribution of electrical properties of an electric field which minimizes in the least squares sense the difference between measured and computed boundary response to excitation. In this paper we briefly review the basic analytical methods developed for this system. We then extend these methods to three dimensions, add a method for preconditioning voltages for error correction, describe methods for optimizing the resolution of a target by providing optimal excitation patterns and then describe the overall numerical sensitivity. The second paper then demonstrates the ability of this system to image multiple, separate, differently-sized two-dimensional or three-dimensional targets with demonstrated linear sensitivity of over 30:1 with maximum possible linear sensitivity of one part in 1300 based on our ability to distinguish variations from a homogeneous background. (author)

  10. A new index of hemodialysis adequacy: clearance x dialysis time / bioelectrical resistance.

    Science.gov (United States)

    Basile, Carlo; Vernaglione, Luigi; Lomonte, Carlo; Bellizzi, Vincenzo; Dambrosio, Nicola; Di Iorio, Biagio

    2010-01-01

    Kt/V urea was established as an index of hemodialysis (HD) adequacy. The use of V urea (as derived by the Watson et al formulae) as a normalizing factor has been questioned, and alternative parameters such as body weight 0.67 (W 0.67), body surface area (BSA), resting energy expenditure (REE), high metabolic rate organ (HMRO) mass and liver size (LV) have been proposed (respective HD adequacy indices: Kt/W 0.67, Kt/BSA, Kt/REE, Kt/HMRO and Kt/LV). The present study aimed to calculate the 6 previously described normalizing factors (all obtained utilizing anthropometric variables) and to measure bioelectrical resistance (R), an independent and directly achievable biological parameter, in 481 white, disease-free individuals and 270 white prevalent HD patients, pair-matched by age, body weight and height, after stratification by sex. Further, we aimed to evaluate the effect of substituting BSA, W 0.67, REE, HMRO, LV and R for V urea as denominator in Kt/V urea on the distribution of target dialysis dose in a cohort of 1,058 white prevalent HD patients. All individuals underwent 1 single-frequency bioelectrical impedance measurement, on the nondominant side of the body, injecting 800 μA at 50 kHz alternating sinusoidal current with a standard tetrapolar technique. When comparing pair-matched disease-free men and women with HD men and women, respectively, only R was statistically significantly different (pcalculations which utilize anthropometric variables. In contrast, R is a biological parameter which can be directly measured in the clinical setting by means of a simple, low-cost, fast and repeatable procedure. Even though Kt/R is probably the most appropriate method for scaling dialysis dose among those evaluated in the present study, further work is required to develop these concepts and translate them into rigorous outcome-based adequacy targets suitable for clinical usage.

  11. Quantitative electromechanical impedance method for nondestructive testing based on a piezoelectric bimorph cantilever

    International Nuclear Information System (INIS)

    Fu, Ji; Tan, Chi; Li, Faxin

    2015-01-01

    The electromechanical impedance (EMI) method, which holds great promise in structural health monitoring (SHM), is usually treated as a qualitative method. In this work, we proposed a quantitative EMI method based on a piezoelectric bimorph cantilever using the sample’s local contact stiffness (LCS) as the identification parameter for nondestructive testing (NDT). Firstly, the equivalent circuit of the contact vibration system was established and the analytical relationship between the cantilever’s contact resonance frequency and the LCS was obtained. As the LCS is sensitive to typical defects such as voids and delamination, the proposed EMI method can then be used for NDT. To verify the equivalent circuit model, two piezoelectric bimorph cantilevers were fabricated and their free resonance frequencies were measured and compared with theoretical predictions. It was found that the stiff cantilever’s EMI can be well predicted by the equivalent circuit model while the soft cantilever’s cannot. Then, both cantilevers were assembled into a homemade NDT system using a three-axis motorized stage for LCS scanning. Testing results on a specimen with a prefabricated defect showed that the defect could be clearly reproduced in the LCS image, indicating the validity of the quantitative EMI method for NDT. It was found that the single-frequency mode of the EMI method can also be used for NDT, which is faster but not quantitative. Finally, several issues relating to the practical application of the NDT method were discussed. The proposed EMI-based NDT method offers a simple and rapid solution for damage evaluation in engineering structures and may also shed some light on EMI-based SHM. (paper)

  12. NUMERICAL SIMULATION OF ELECTRICAL IMPEDANCE TOMOGRAPHY PROBLEM AND STUDY OF APPROACH BASED ON FINITE VOLUME METHOD

    Directory of Open Access Journals (Sweden)

    Ye. S. Sherina

    2014-01-01

    Full Text Available This research has been aimed to carry out a study of peculiarities that arise in a numerical simulation of the electrical impedance tomography (EIT problem. Static EIT image reconstruction is sensitive to a measurement noise and approximation error. A special consideration has been given to reducing of the approximation error, which originates from numerical implementation drawbacks. This paper presents in detail two numerical approaches for solving EIT forward problem. The finite volume method (FVM on unstructured triangular mesh is introduced. In order to compare this approach, the finite element (FEM based forward solver was implemented, which has gained the most popularity among researchers. The calculated potential distribution with the assumed initial conductivity distribution has been compared to the analytical solution of a test Neumann boundary problem and to the results of problem simulation by means of ANSYS FLUENT commercial software. Two approaches to linearized EIT image reconstruction are discussed. Reconstruction of the conductivity distribution is an ill-posed problem, typically requiring a large amount of computation and resolved by minimization techniques. The objective function to be minimized is constructed of measured voltage and calculated boundary voltage on the electrodes. A classical modified Newton type iterative method and the stochastic differential evolution method are employed. A software package has been developed for the problem under investigation. Numerical tests were conducted on simulated data. The obtained results could be helpful to researches tackling the hardware and software issues for medical applications of EIT.

  13. 基于直接寻找法的电阻抗断层成像%Electrical Impedance Tomography Based on Direct Search Method

    Institute of Scientific and Technical Information of China (English)

    蔡畅; 严壮志

    2005-01-01

    Solution to impedance distribution in electrical impedance tomography (EIT) is an ill-posed nonlinear inverse problem. It is especially difficult to reconstruct an EIT image in the center area of a measured object. Tikhonov regularization with some prior information is a sound regularization method for static electrical impedance tomography under the condition that some true impedance distribution information is known a priori. This paper presents a direct search method (DSM) as pretreatment of image reconstruction through which one not only can construct a regularization matrix which maylocate in areas of impedance change, but also can obtain an initial impedance distribution more similar to the true impedance distribution, as well as better current modes which can better distinguish the initial distribution and the true distribution. Simulation results indicate that, by using DSM, resolution in the center area of the measured object can be improved significantly.

  14. Assessment of dental implant stability by means of the electromechanical impedance method

    International Nuclear Information System (INIS)

    Boemio, Giovanni; Rizzo, Piervincenzo; Nardo, Luigi De

    2011-01-01

    Implant stability is a prerequisite for functional recovery in load-bearing prostheses. Robust, reliable and noninvasive methods to assess the bone interface of dental and orthopedic implants are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, a study of the feasibility of a noninvasive method based on electromechanical impedance (EMI) to assess dental prostheses stability is presented. Two different dental screws were entrenched in polyurethane foams (Sawbones ® ) and immersed in a solution of nitric acid to allow material degradation, inversely simulating a bone healing process. This process was monitored by bonding a piezoceramic transducer (PZT) to the implant and measuring the admittance of the PZT over time. It was found that the PZT's conductance and the statistical features associated with its analysis were sensitive to the degradation of the foams and can be correlated to the Sawbones mechanical properties. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of implanted prostheses

  15. Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

    Science.gov (United States)

    Komarkova, Tereza; Fiala, Pavel; Steinbauer, Miloslav; Roubal, Zdenek

    2018-02-01

    Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor-sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

  16. Computational method for estimating boundary of abdominal subcutaneous fat for absolute electrical impedance tomography.

    Science.gov (United States)

    Yamaguchi, Tohru F; Okamoto, Yoshiwo

    2018-01-01

    Abdominal fat accumulation is considered an essential indicator of human health. Electrical impedance tomography has considerable potential for abdominal fat imaging because of the low specific conductivity of human body fat. In this paper, we propose a robust reconstruction method for high-fidelity conductivity imaging by abstraction of the abdominal cross section using a relatively small number of parameters. Toward this end, we assume homogeneous conductivity in the abdominal subcutaneous fat area and characterize its geometrical shape by parameters defined as the ratio of the distance from the center to boundary of subcutaneous fat to the distance from the center to outer boundary in 64 equiangular directions. To estimate the shape parameters, the sensitivity of the noninvasively measured voltages with respect to the shape parameters is formulated for numerical optimization. Numerical simulations are conducted to demonstrate the validity of the proposed method. A 3-dimensional finite element method is used to construct a computer model of the human abdomen. The inverse problems of shape parameters and conductivities are solved concurrently by iterative forward and inverse calculations. As a result, conductivity images are reconstructed with a small systemic error of less than 1% for the estimation of the subcutaneous fat area. A novel method is devised for estimating the boundary of the abdominal subcutaneous fat. The fidelity of the overall reconstructed image to the reference image is significantly improved. The results demonstrate the possibility of realization of an abdominal fat scanner as a low-cost, radiation-free medical device. Copyright © 2017 John Wiley & Sons, Ltd.

  17. On the impedance of galvanic cells XXVI. Application of the complex plane method in the case of mixed currents

    NARCIS (Netherlands)

    Dekker, B.G.; Sluyters-Rehbach, M.; Sluyters, J.H.

    1969-01-01

    The applicability of the complex plane method for the evaluation of the impedance parameters in the case of two simultaneously proceeding electrode reactions is discussed. It is shown that the possibility of the evaluation depends strongly on the values of the irreversibility quotients of both

  18. Application of the Method of Auxiliary Sources for the Analysis of Plane-Wave Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  19. A Simultaneous and Continuous Excitation Method for High-Speed Electrical Impedance Tomography with Reduced Transients and Noise Sensitivity

    Directory of Open Access Journals (Sweden)

    Antoine Dupré

    2018-03-01

    Full Text Available This paper presents a concept for soft field tomographic scan of all the projections of electromagnetic waves emanating from an array of electrodes. Instead of the sequential excitation of all pairs of electrodes in the list of all projections, the new method present here consists of a single and continuous excitation. This excitation signal is the linear combination of the excitation signals in the projection set at different AC frequencies. The response to a given projection is discriminated by selecting the corresponding AC frequency component in the signal spectra of the digitally demodulated signals. The main advantage of this method is the suppression of transients after each projection, which is particularly problematic in electrical impedance tomography due to contact impedance phenomena and skin effect. The second benefit over the sequential scan method is the increased number of samples for each measurement for reduced noise sensitivity with digital demodulation. The third benefit is the increased temporal resolution in high-speed applications. The main drawback is the increased number of signal sources required (one per electrode. This paper focuses on electrical impedance tomography, based on earlier work by the authors. An experimental proof-of-concept using a simple 4-electrodes electrical impedance tomographic system is presented using simulations and laboratory data. The method presented here may be extended to other modalities (ultrasonic, microwave, optical, etc..

  20. Stabilization of time domain acoustic boundary element method for the interior problem with impedance boundary conditions.

    Science.gov (United States)

    Jang, Hae-Won; Ih, Jeong-Guon

    2012-04-01

    The time domain boundary element method (BEM) is associated with numerical instability that typically stems from the time marching scheme. In this work, a formulation of time domain BEM is derived to deal with all types of boundary conditions adopting a multi-input, multi-output, infinite impulse response structure. The fitted frequency domain impedance data are converted into a time domain expression as a form of an infinite impulse response filter, which can also invoke a modeling error. In the calculation, the response at each time step is projected onto the wave vector space of natural radiation modes, which can be obtained from the eigensolutions of the single iterative matrix. To stabilize the computation, unstable oscillatory modes are nullified, and the same decay rate is used for two nonoscillatory modes. As a test example, a transient sound field within a partially lined, parallelepiped box is used, within which a point source is excited by an octave band impulse. In comparison with the results of the inverse Fourier transform of a frequency domain BEM, the average of relative difference norm in the stabilized time response is found to be 4.4%.

  1. Lactate threshold by muscle electrical impedance in professional rowers

    Science.gov (United States)

    Jotta, B.; Coutinho, A. B. B.; Pino, A. V.; Souza, M. N.

    2017-04-01

    Lactate threshold (LT) is one of the physiological parameters usually used in rowing sport training prescription because it indicates the transitions from aerobic to anaerobic metabolism. Assessment of LT is classically based on a series of values of blood lactate concentrations obtained during progressive exercise tests and thus has an invasive aspect. The feasibility of noninvasive LT estimative through bioelectrical impedance spectroscopy (BIS) data collected in thigh muscles during rowing ergometer exercise tests was investigated. Nineteen professional rowers, age 19 (mean) ± 4.8 (standard deviation) yr, height 187.3 ± 6.6 cm, body mass 83 ± 7.7 kg, and training experience of 7 ± 4 yr, were evaluated in a rowing ergometer progressive test with paired measures of blood lactate concentration and BIS in thigh muscles. Bioelectrical impedance data were obtained by using a bipolar method of spectroscopy based on the current response to a voltage step. An electrical model was used to interpret BIS data and to derive parameters that were investigated to estimate LT noninvasively. From the serial blood lactate measurements, LT was also determined through Dmax method (LTDmax). The zero crossing of the second derivative of kinetic of the capacitance electrode (Ce), one of the BIS parameters, was used to estimate LT. The agreement between the LT estimates through BIS (LTBIS) and through Dmax method (LTDmax) was evaluated using Bland-Altman plots, leading to a mean difference between the estimates of just 0.07 W and a Pearson correlation coefficient r = 0.85. This result supports the utilization of the proposed method based on BIS parameters for estimating noninvasively the lactate threshold in rowing.

  2. Phase boundary estimation in electrical impedance tomography using the Hooke and Jeeves pattern search method

    International Nuclear Information System (INIS)

    Khambampati, Anil Kumar; Kim, Kyung Youn; Ijaz, Umer Zeeshan; Lee, Jeong Seong; Kim, Sin

    2010-01-01

    In industrial processes, monitoring of heterogeneous phases is crucial to the safety and operation of the engineering structures. Particularly, the visualization of voids and air bubbles is advantageous. As a result many studies have appeared in the literature that offer varying degrees of functionality. Electrical impedance tomography (EIT) has already been proved to be a hallmark for process monitoring and offers not only the visualization of the resistivity profile for a given flow mixture but is also used for detection of phase boundaries. Iterative image reconstruction algorithms, such as the modified Newton–Raphson (mNR) method, are commonly used as inverse solvers. However, their utility is problematic in a sense that they require the initial solution in close proximity of the ground truth. Furthermore, they also rely on the gradient information of the objective function to be minimized. Therefore, in this paper, we address all these issues by employing a direct search algorithm, namely the Hooke and Jeeves pattern search method, to estimate the phase boundaries that directly minimizes the cost function and does not require the gradient information. It is assumed that the resistivity profile is known a priori and therefore the unknown information will be the size and location of the object. The boundary coefficients are parameterized using truncated Fourier series and are estimated using the relationship between the measured voltages and injected currents. Through extensive simulation and experimental result and by comparison with mNR, we show that the Hooke and Jeeves pattern search method offers a promising prospect for process monitoring

  3. System-on-Chip Integration of a New Electromechanical Impedance Calculation Method for Aircraft Structure Health Monitoring

    Directory of Open Access Journals (Sweden)

    Daniel Medale

    2012-10-01

    Full Text Available The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline.

  4. System-on-chip integration of a new electromechanical impedance calculation method for aircraft structure health monitoring.

    Science.gov (United States)

    Boukabache, Hamza; Escriba, Christophe; Zedek, Sabeha; Medale, Daniel; Rolet, Sebastien; Fourniols, Jean Yves

    2012-10-11

    The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC) technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline.

  5. A Bioassay System Using Bioelectric Signals from Small Fish

    Science.gov (United States)

    Terawaki, Mitsuru; Soh, Zu; Hirano, Akira; Tsuji, Toshio

    Although the quality of tap water is generally examined using chemical assay, this method cannot be used for examination in real time. Against such a background, the technique of fish bioassay has attracted attention as an approach that enables constant monitoring of aquatic contamination. The respiratory rhythms of fish are considered an efficient indicator for the ongoing assessment of water quality, since they are sensitive to chemicals and can be indirectly measured from bioelectric signals generated by breathing. In order to judge aquatic contamination accurately, it is necessary to measure bioelectric signals from fish swimming freely as well as to stably discriminate measured signals, which vary between individuals. However, no bioassay system meeting the above requirements has yet been established. This paper proposes a bioassay system using bioelectric signals generated from small fish in free-swimming conditions. The system records signals using multiple electrodes to cover the extensive measurement range required in a free-swimming environment, and automatically discriminates changes in water quality from signal frequency components. This discrimination is achieved through an ensemble classification method using probability neural networks to solve the problem of differences between individual fish. The paper also reports on the results of related validation experiments, which showed that the proposed system was able to stably discriminate between water conditions before and after bleach exposure.

  6. Impedances of electrochemically impregnated nickel electrodes as functions of potential, KOH concentration, and impregnation method

    Science.gov (United States)

    Reid, Margaret A.

    1989-01-01

    Impedances of fifteen electrodes form each of the four U.S. manufactures were measured at 0.200 V vs. the Hg/HgO reference electrode. This corresponds to a voltage of 1.145 for a Ni/H2 cell. Measurements were also made of a representative sample of these at 0.44 V. At the higher voltage, the impedances were small and very similar, but at the lower voltage there were major differences between manufacturers. Electrodes from the same manufacturers showed only small differences. The impedances of electrodes from two manufacturers were considerably different in 26 percent KOH from those in 31 percent KOH. These preliminary results seen to correlate with the limited data from earlier life testing of cells from these manufacturers. The impedances of cells being tested for Space Station Freedom are being followed, and more impendance measurements of electrodes are being performed as functions of manufacturer, voltage, electrolyte concentration, and cycle history in hopes of finding better correlations of impedance with life.

  7. Applicability of impedance measuring method to the detection of irradiation treatment of potatoes

    International Nuclear Information System (INIS)

    Hayashi, Toru; Todoriki, Setsuko; Otobe, Kazunori; Sugiyama, Junnichi

    1993-01-01

    The incubation condition of potato tubers prior to impedance measurement greatly influenced the reliability of detection of irradiated potatoes; the impedance ratio at 5 kHz to 50 kHz (Z 5k /Z 50k ) determined at 22degC at an apical region of tuber which was pre-incubated at 22degC for 3 days or longer resulted in the best detection of radiation treatment of potatoes. The impedance ratio was dependent upon dose applied to potato tubers. Potatoes irradiated at 100 Gy could be distinguished from unirradiated potatoes for 10 cultivars of potatoes. The impedance ratio of potatoes irradiated at the same dose was little influenced by the planting locality if the cultivar was the same, although the ratio varied with potato cultivars. These results indicate that irradiated potatoes can be detected if the potato cultivar is known. Potatoes 'Danshaku' commercially irradiated at the Shihiro Potato Irradiation Center could be differentiated from unirradiated 'Danshaku' at different planting localities; the impedance ratio was lower than 2.75 for the unirradiated potatoes and higher than 2.75 for the irradiated ones. (author)

  8. A Method of Function Space for Vertical Impedance Function of a Circular Rigid Foundation on a Transversely Isotropic Ground

    Directory of Open Access Journals (Sweden)

    Morteza Eskandari-Ghadi

    2014-06-01

    Full Text Available This paper is concerned with investigation of vertical impedance function of a surface rigid circular foundation resting on a semi-infinite transversely isotropic alluvium. To this end, the equations of motion in cylindrical coordinate system, which because of axissymmetry are two coupled equations, are converted into one partial differential equation using a method of potential function. The governing partial differential equation for the potential function is solved via implementing Hankel integral transforms in radial direction. The vertical and radial components of displacement vector are determined with the use of transformed displacement-potential function relationships. The mixed boundary conditions at the surface are satisfied by specifying the traction between the rigid foundation and the underneath alluvium in a special function space introduced in this paper, where the vertical displacements are forced to satisfy the rigid boundary condition. Through exercising these restraints, the normal traction and then the vertical impedance function are obtained. The results are then compared with the existing results in the literature for the simpler case of isotropic half-space, which shows an excellent agreement. Eventually, the impedance functions are presented in terms of dimensionless frequency for different materials. The method presented here may be used to obtain the impedance function in any other direction as well as in buried footing in layered media.

  9. Electrical Impedance Tomography: a new study method for neonatal Respiratory Distress Syndrome?

    Science.gov (United States)

    Chatziioannidis, I; Samaras, T; Nikolaidis, N

    2011-01-01

    Treatment of cardiorespiratory system diseases is a procedure that usually demands data collection on terms of the anatomy and the operation of the organs that are under study. Electrical Impedance Tomography (EIT) is an alternative approach, in comparison to existing techniques. With EIT electrodes are placed in the perimeter of the human body and images of the estimated organ are reconstructed, using the measurement of its impendence (or resistance) distribution and determining its alteration through time, while at the same time the patient is not exposed to ionizing radiation. Its clinical use presupposes the correct placement of the electrodes over the perimeter of the human body, the rapid data collection and electrical safety. It is a low cost technique and it is implemented near the patient. It is able to determine the distribution of ventilation, blood supply, diffused or localized lung defects, but it can also estimate therapeutic interventions or alteration to assisted ventilation of the neonate. EIT was developed at the beginning of the 1980s, but it has only recently begun to be implemented on neonates, and especially in the study of their respiratory system function. The low rate of image analysis is considered to be a drawback, but it is offset by the potential offered for the estimation of lungs' function (both under normal and pathological conditions), since ventilation and resistance are two quite similar concepts. In this review the most important studies about EIT are mentioned as a method of estimating respiratory distress syndrome in neonates. In terms of the above mentioned development, it is supposed that this technique will offer a great amount of help to the doctor in his / her estimations of the cardiorespiratory system and to his / her selection of the best intervening strategies. PMID:22435017

  10. An efficient impedance method for induced field evaluation based on a stabilized Bi-conjugate gradient algorithm

    International Nuclear Information System (INIS)

    Wang Hua; Liu Feng; Crozier, Stuart; Xia Ling

    2008-01-01

    This paper presents a stabilized Bi-conjugate gradient algorithm (BiCGstab) that can significantly improve the performance of the impedance method, which has been widely applied to model low-frequency field induction phenomena in voxel phantoms. The improved impedance method offers remarkable computational advantages in terms of convergence performance and memory consumption over the conventional, successive over-relaxation (SOR)-based algorithm. The scheme has been validated against other numerical/analytical solutions on a lossy, multilayered sphere phantom excited by an ideal coil loop. To demonstrate the computational performance and application capability of the developed algorithm, the induced fields inside a human phantom due to a low-frequency hyperthermia device is evaluated. The simulation results show the numerical accuracy and superior performance of the method.

  11. An efficient impedance method for induced field evaluation based on a stabilized Bi-conjugate gradient algorithm.

    Science.gov (United States)

    Wang, Hua; Liu, Feng; Xia, Ling; Crozier, Stuart

    2008-11-21

    This paper presents a stabilized Bi-conjugate gradient algorithm (BiCGstab) that can significantly improve the performance of the impedance method, which has been widely applied to model low-frequency field induction phenomena in voxel phantoms. The improved impedance method offers remarkable computational advantages in terms of convergence performance and memory consumption over the conventional, successive over-relaxation (SOR)-based algorithm. The scheme has been validated against other numerical/analytical solutions on a lossy, multilayered sphere phantom excited by an ideal coil loop. To demonstrate the computational performance and application capability of the developed algorithm, the induced fields inside a human phantom due to a low-frequency hyperthermia device is evaluated. The simulation results show the numerical accuracy and superior performance of the method.

  12. RHIC injection kicker impedance

    International Nuclear Information System (INIS)

    Mane, V.; Peggs, S.; Trbojevic, D.; Zhang, W.

    1995-01-01

    The longitudinal impedance of the RHIC injection kicker is measured using the wire method up to a frequency of 3 GHz. The mismatch between the 50 ohm cable and the wire and pipe system is calibrated using the TRL calibration algorithm. Various methods of reducing the impedance, such as coated ceramic pipe and copper strips are investigated

  13. Estimating the absorptive root area in Norway spruce by using the common direct and indirect earth impedance methods

    Czech Academy of Sciences Publication Activity Database

    Čermák, J.; Cudlín, Pavel; Gebauer, R.; Borja, I.; Martinková, M.; Staněk, Z.; Koller, J.; Neruda, J.; Nadezhdina, N.

    2013-01-01

    Roč. 372, 1-2 (2013), s. 401-415 ISSN 0032-079X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk OC10023 Institutional support: RVO:67179843 Keywords : Active absorptive fine root area index * Fine root surface * Modified earth impedance * Picea abies * Root research methods Subject RIV: EH - Ecology, Behaviour Impact factor: 3.235, year: 2013

  14. Impedance Scaling and Impedance Control

    International Nuclear Information System (INIS)

    Chou, W.; Griffin, J.

    1997-06-01

    When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ''normal'' way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane

  15. Intracranial electrical impedance tomography: a method of continuous monitoring in an animal model of head trauma.

    Science.gov (United States)

    Manwaring, Preston K; Moodie, Karen L; Hartov, Alexander; Manwaring, Kim H; Halter, Ryan J

    2013-10-01

    Electrical impedance tomography (EIT) is a method that can render continuous graphical cross-sectional images of the brain's electrical properties. Because these properties can be altered by variations in water content, shifts in sodium concentration, bleeding, and mass deformation, EIT has promise as a sensitive instrument for head injury monitoring to improve early recognition of deterioration and to observe the benefits of therapeutic intervention. This study presents a swine model of head injury used to determine the detection capabilities of an inexpensive bedside EIT monitoring system with a novel intracranial pressure (ICP)/EIT electrode combination sensor on induced intraparenchymal mass effect, intraparenchymal hemorrhage, and cessation of brain blood flow. Conductivity difference images are shown in conjunction with ICP data, confirming the effects. Eight domestic piglets (3-4 weeks of age, mean 10 kg), under general anesthesia, were subjected to 4 injuries: induced intraparenchymal mass effect using an inflated, and later, deflated 0.15-mL Fogarty catheter; hemorrhage by intraparenchymal injection of 1-mL arterial blood; and ischemia/infarction by euthanasia. EIT and ICP data were recorded 10 minutes before inducing the injury until 10 minutes after injury. Continuous EIT and ICP monitoring were facilitated by a ring of circumferentially disposed cranial Ag/AgCl electrodes and 1 intraparenchymal ICP/EIT sensor electrode combination. Data were recorded at 100 Hz. Two-dimensional tomographic conductivity difference (Δσ) images, rendered using data before and after an injury, were displayed in real time on an axial circular mesh. Regions of interest (ROI) within the images were automatically selected as the upper or lower 5% of conductivity data depending on the nature of the injury. Mean Δσ within the ROIs and background were statistically analyzed. ROI Δσ was compared with the background Δσ after an injury event using an unpaired, unequal variance

  16. Applications of the conjugate gradient FFT method in scattering and radiation including simulations with impedance boundary conditions

    Science.gov (United States)

    Barkeshli, Kasra; Volakis, John L.

    1991-01-01

    The theoretical and computational aspects related to the application of the Conjugate Gradient FFT (CGFFT) method in computational electromagnetics are examined. The advantages of applying the CGFFT method to a class of large scale scattering and radiation problems are outlined. The main advantages of the method stem from its iterative nature which eliminates a need to form the system matrix (thus reducing the computer memory allocation requirements) and guarantees convergence to the true solution in a finite number of steps. Results are presented for various radiators and scatterers including thin cylindrical dipole antennas, thin conductive and resistive strips and plates, as well as dielectric cylinders. Solutions of integral equations derived on the basis of generalized impedance boundary conditions (GIBC) are also examined. The boundary conditions can be used to replace the profile of a material coating by an impedance sheet or insert, thus, eliminating the need to introduce unknown polarization currents within the volume of the layer. A general full wave analysis of 2-D and 3-D rectangular grooves and cavities is presented which will also serve as a reference for future work.

  17. A Novel Method for Monitoring Data Quality in Electrical Impedance Tomography

    International Nuclear Information System (INIS)

    Adler, Andy; Mamatjan, Yasin; Grychtol, Bartłomiej; Gaggero, Pascal; Justiz, Jörn; Koch, Volker

    2013-01-01

    Electrical impedance tomography (EIT) has the promise to help improve care for patients undergoing ventilation therapy by providing real-time bed-side information on the distribution of ventilation in their lungs. To realise this potential, it is important for an EIT system to provide a reliable and meaningful signal at all times, or alert clinicians when this is not possible. Because the reconstructed images in EIT are sensitive to system instabilities (including electrode connection problems) and artifacts caused by e.g. movement or sweat, there is a need for EIT systems to continuously monitor, recognize and, if possible, correct for such errors. Motivated by this requirement, our paper describes a novel approach to quantitatively measure EIT data quality suitable for online and offline applications. We used a publicly available data set of ventilation data from two pediatric patients with lung disease to evaluate the data quality on clinical data. Results suggest that the developed data quality could be a useful tool for real-time assessment of the quality of EIT data and, hence, to indicate the reliability of any derived physiological information.

  18. Method to measure autonomic control of cardiac function using time interval parameters from impedance cardiography

    International Nuclear Information System (INIS)

    Meijer, Jan H; Boesveldt, Sanne; Elbertse, Eskeline; Berendse, H W

    2008-01-01

    The time difference between the electrocardiogram and impedance cardiogram can be considered as a measure for the time delay between the electrical and mechanical activities of the heart. This time interval, characterized by the pre-ejection period (PEP), is related to the sympathetic autonomous nervous control of cardiac activity. PEP, however, is difficult to measure in practice. Therefore, a novel parameter, the initial systolic time interval (ISTI), is introduced to provide a more practical measure. The use of ISTI instead of PEP was evaluated in three groups: young healthy subjects, patients with Parkinson's disease, and a group of elderly, healthy subjects of comparable age. PEP and ISTI were studied under two conditions: at rest and after an exercise stimulus. Under both conditions, PEP and ISTI behaved largely similarly in the three groups and were significantly correlated. It is concluded that ISTI can be used as a substitute for PEP and, therefore, to evaluate autonomic neuropathy both in clinical and extramural settings. Measurement of ISTI can also be used to non-invasively monitor the electromechanical cardiac time interval, and the associated autonomic activity, under physiological circumstances

  19. Electrical Impedance Spectroscopy for Quality Assessment of Meat and Fish: A Review on Basic Principles, Measurement Methods, and Recent Advances

    Directory of Open Access Journals (Sweden)

    Xin Zhao

    2017-01-01

    Full Text Available Electrical impedance spectroscopy (EIS, as an effective analytical technique for electrochemical system, has shown a wide application for food quality and safety assessment recently. Individual differences of livestock cause high variation in quality of raw meat and fish and their commercialized products. Therefore, in order to obtain the definite quality information and ensure the quality of each product, a fast and on-line detection technology is demanded to be developed to monitor product processing. EIS has advantages of being fast, nondestructive, inexpensive, and easily implemented and shows potential to develop on-line detecting instrument to replace traditional methods to realize time, cost, skilled persons saving and further quality grading. This review outlines the fundamental theories and two common measurement methods of EIS applied to biological tissue, summarizes its application specifically for quality assessment of meat and fish, and discusses challenges and future trends of EIS technology applied for meat and fish quality assessment.

  20. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...... in the transmission such as the earphone impedance. In order to determine the acoustic impedances of human ear canals, the standardized method for measurement of complex impedances used for the measurement of the audiometric earphone impedances is applied. It is based on the transfer function between two microphone...... locations in an impedance tube. The end of the tube representing the measurement plane is placed at the ear canal entrance. Thus, the impedance seen from the entrance inward is measured on 25 subjects. Most subjects participated in the previous measurement of the ratio between the pressures at the open...

  1. Study of colored anodized aluminum with calcon in sulfuric acidic solution using cyclic voltammetry and impedance measurement methods

    Energy Technology Data Exchange (ETDEWEB)

    Norouzi, P.; Ganjali, M.R.; Golmohamaddi, M.; Mousavi, S. [Department of Chemistry, Faculty of Science, University of Tehran, Tehran (Iran); Vatankhah, G. [Iranian Organization for Science and Technology (IROST), Isfahan Center, A5 Ghezelbash Avenue, Tohid Street, Isfahan 8173954541 (Iran)

    2003-04-01

    The effect of coloring condition of Al with Calcon (sodium 2,2'-dihydroxy-azonaphthalene-4-sulfonate), on the corrosion resistance of Al in 0.1 M sulfuric acid solution was studied, using cyclic voltammetry and measurement of impedance noise methods. The changes in the corrosion resistance of colored aluminum electrodes were evaluated by measuring the magnitude of impedance and cyclic voltammetric responses of anodized and colored electrodes. An irreversible corrosion response was observed at the cyclic voltammogram of the colored aluminum electrode. The current and threshold potential of corrosion responses strongly depends on the applied conditions during anodizing, coloring and sealing stages. In addition, significant changes in impedance at the ac voltammogram and noise level at some ac frequencies were observed, when the electrodes were colored under various conditions. In this regard, the surface of the electrode was studied by Scanning Electron Microscopy (SEM). Comparison of SEM images of the colored and uncolored aluminum specimens showed that the colored surface contained a significant numbers of pits. The results indicated that coloring aluminum with Calcon could reduce corrosion resistance of aluminum and increase roughness of the oxide film. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Mit Hilfe zyklischer Voltammetrie und Messungen mit Impedanzrauschmethoden wurde der Einfluss der Faerbungsbedingungen von Aluminium mit Calcon (Natrium 2,2'-Dihydroxyazonaphthalen-4-Sulfonat) auf den Korrosionswiderstand von Aluminium in 0,1 M Schwefelsaeure untersucht. Die Veraenderungen des Korrosionswiderstandes von gefaerbten Aluminiumelektroden wurden durch Messungen der Hoehe der Impedanzreaktion bzw. der Reaktion bei der zyklischen Voltammetrie von anodisierten und gefaerbten Elektroden beurteilt. Eine irreversible Korrosionsreaktion wurde beim zyklischen Voltammogramm der gefaerbten Aluminiumelektrode beobachtet. Der Strom und das

  2. An efficient 3-D eddy-current solver using an independent impedance method for transcranial magnetic stimulation.

    Science.gov (United States)

    De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc

    2011-02-01

    In many important bioelectromagnetic problem settings, eddy-current simulations are required. Examples are the reduction of eddy-current artifacts in magnetic resonance imaging and techniques, whereby the eddy currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the eddy currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the eddy-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations.

  3. The method of impedance transformation for electromagnetic waves propagating in one-dimension plasma photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jingfeng; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Gao, Ruilin; Jia, Jieshu; Wang, Ying; Zhou, Zhongxiang, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Wang, Xiaoou [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Wu, Jian [National Key Laboratory of Electromagnetic Environment (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China); Li, Hui [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory of Electromagnetic Environment (LEME), China Research Institute of Radio Wave Propagation, Beijing 102206 (China)

    2016-08-15

    This study focuses on the transmission of normal-incidence electromagnetic waves in one-dimensional plasma photonic crystals. Using the Maxwell's equations in a medium, a method that is based on the concept of impendence is employed to perform the simulation. The accuracy of the method was evaluated by simulating a one-layer plasma and conventional photonic crystal. In frequency-domain, the transmission and reflection coefficients in the unmagnetized plasma photonic crystal were calculated, and the influence factors on plasma photonic crystals including dielectric constants of dielectric, spatial period, filling factor, plasma frequency, and collision frequency were studied.

  4. Microwave Impedance Measurement for Nanoelectronics

    Directory of Open Access Journals (Sweden)

    M. Randus

    2011-04-01

    Full Text Available The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances due to insufficient sensitivity of the reflection coefficient to impedance of the DUT. This paper brings theoretical description and experimental verification of a method developed especially for measurement of extreme impedances. The method can significantly improve measurement sensitivity and reduce errors caused by the VNA. It is based on subtraction (or addition of a reference reflection coefficient and the reflection coefficient of the DUT by a passive network, amplifying the resulting signal by an amplifier and measuring the amplified signal as a transmission coefficient by a common vector network analyzer (VNA. A suitable calibration technique is also presented.

  5. Electromagnetic Scattering Analysis of Coated Conductors With Edges Using the Method of Auxiliary Sources (MAS) in Conjunction With the Standard Impedance Boundary Condition (SIBC)

    DEFF Research Database (Denmark)

    Anastassiu, H.T.; D.I.Kaklamani, H.T.; Economou, D.P.

    2002-01-01

    A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer is initia......A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer...

  6. A DTI-based model for TMS using the independent impedance method with frequency-dependent tissue parameters

    Science.gov (United States)

    De Geeter, N.; Crevecoeur, G.; Dupré, L.; Van Hecke, W.; Leemans, A.

    2012-04-01

    Accurate simulations on detailed realistic head models are necessary to gain a better understanding of the response to transcranial magnetic stimulation (TMS). Hitherto, head models with simplified geometries and constant isotropic material properties are often used, whereas some biological tissues have anisotropic characteristics which vary naturally with frequency. Moreover, most computational methods do not take the tissue permittivity into account. Therefore, we calculate the electromagnetic behaviour due to TMS in a head model with realistic geometry and where realistic dispersive anisotropic tissue properties are incorporated, based on T1-weighted and diffusion-weighted magnetic resonance images. This paper studies the impact of tissue anisotropy, permittivity and frequency dependence, using the anisotropic independent impedance method. The results show that anisotropy yields differences up to 32% and 19% of the maximum induced currents and electric field, respectively. Neglecting the permittivity values leads to a decrease of about 72% and 24% of the maximum currents and field, respectively. Implementing the dispersive effects of biological tissues results in a difference of 6% of the maximum currents. The cerebral voxels show limited sensitivity of the induced electric field to changes in conductivity and permittivity, whereas the field varies approximately linearly with frequency. These findings illustrate the importance of including each of the above parameters in the model and confirm the need for accuracy in the applied patient-specific method, which can be used in computer-assisted TMS.

  7. Grid impedance estimation based hybrid islanding detection method for AC microgrids

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

    2017-01-01

    This paper focuses on a hybrid islanding detection algorithm for parallel-inverters-based microgrids. The proposed algorithm is implemented on the unit ensuring the control of the intelligent bypass switch connecting or disconnecting the microgrid from the utility. This method employs a grid...... to avoid interactions with other units. The selected inverter will be the one closest to the controllable distributed generation system or to a healthy grid side in case of meshed microgrid with multiple-grid connections. The detection algorithm is applied to quickly detect the resonance phenomena, so...

  8. Electrochemical Impedance Spectroscopy—A Simple Method for the Characterization of Polymer Inclusion Membranes Containing Aliquat 336

    Science.gov (United States)

    O'Rourke, Michelle; Duffy, Noel; De Marco, Roland; Potter, Ian

    2011-01-01

    Electrochemical impedance spectroscopy (EIS) has been used to estimate the non-frequency dependent (static) dielectric constants of base polymers such as poly(vinyl chloride) (PVC), cellulose triacetate (CTA) and polystyrene (PS). Polymer inclusion membranes (PIMs) containing different amounts of PVC or CTA, along with the room temperature ionic liquid Aliquat 336 and plasticizers such as trisbutoxyethyl phosphate (TBEP), dioctyl sebecate (DOS) and 2-nitrophenyloctyl ether (NPOE) have been investigated. In this study, the complex and abstract method of EIS has been applied in a simple and easy to use way, so as to make the method accessible to membrane scientists and engineers who may not possess the detailed knowledge of electrochemistry and interfacial science needed for a rigorous interpretation of EIS results. The EIS data reported herein are internally consistent with a percolation threshold in the dielectric constant at high concentrations of Aliquat 336, which illustrates the suitability of the EIS technique since membrane percolation with ion exchangers is a well-known phenomenon. PMID:24957616

  9. Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes

    International Nuclear Information System (INIS)

    Radicke, Marcus

    2009-01-01

    The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm 2 and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [de

  10. Biohydrogen, bioelectricity and bioalcohols from cellulosic materials

    Energy Technology Data Exchange (ETDEWEB)

    Nissila, M.

    2013-03-01

    The demand for renewable energy is increasing due to increasing energy demand and global warming associated with increasing use of fossil fuels. Renewable energy can be derived from biological production of energy carriers from cellulosic biomass. These biochemical processes include biomass fermentation to hydrogen, methane and alcohols, and bioelectricity production in microbial fuel cells (MFCs). The objective of this study was to investigate the production of different energy carriers (hydrogen, methane, ethanol, butanol, bioelectricity) through biochemical processes. Hydrogen production potential of a hot spring enrichment culture from different sugars was determined, and hydrogen was produced continuously from xylose. Cellulolytic and hydrogenic cultures were enriched on cellulose, cellulosic pulp materials, and on silage at different process conditions. The enrichment cultures were further characterized. The effect of acid pretreatment on hydrogen production from pulp materials was studied and compared to direct pulp fermentation to hydrogen. Electricity and alcohol(s) were simultaneously produced from xylose in MFCs and the exoelectrogenic and alcohologenic enrichment cultures were characterized. In the end, the energy yields obtained from different biochemical processes were determined and compared. In this study, cultures carrying out simultaneous cellulose hydrolysis and hydrogen fermentation were enriched from different sources at different operational conditions. These cultures were successfully utilized for cellulose to hydrogen fermentation in batch systems. Based on these results further research should be conducted on continuous hydrogen production from cellulosic materials.

  11. Method of Grasping Control by Computing Internal and External Impedances for Two Robot Fingers, and Its Application to Admittance Control of a Robot Hand-Arm System

    Directory of Open Access Journals (Sweden)

    Jian Huang

    2015-08-01

    Full Text Available Impedance control is an important technology used in the grasping control of a robot hand. Numerous studies related to grasping algorithms have been reported in recent years, with the contact force between robot fingers and the object to be grasped being primarily discussed in most cases. Generally, a coupling effect occurs between the internal loop of the grasping operation and the external loop of the interaction with the environment when a multi-fingered robot hand is used to complete a contact task. Therefore, a robot hand cannot hold an object using a large external force to complete a wide range of tasks by applying the conventional method. In this paper, the coupling of the internal/external forces occurring in grasping operations using multiple fingers is analysed. Then, improved impedance control based on the previous method is proposed as an effective tool to solve the problem of grasping failure caused by single-finger contact. Furthermore, a method for applying the improved grasping algorithm to the admittance control of a robot hand-arm system is also proposed. The proposed method divides the impedance effect into the grasping control of the hand and the cooperative control of the arm, so that expanding the task space and increasing the flexibility of impedance adjustment can be achieved. Experiments were conducted to demonstrate the effectiveness of the proposed method.

  12. Determination of kinetic parameters of Fe sup 3+ reduction mediated by a polyaniline film using steady-state and impedance methods

    Energy Technology Data Exchange (ETDEWEB)

    Deslouis, C. (LP15 du CNRS, Physique des Liquides et Electrochimie, Lab. de l' Univ. Pierre et Marie Curie, 75252 Paris Cedex 05 (FR)); Musiani, M.M.; Pagura, C.; Tribollet, C. (Inst. di Polarografia de Elettrochimica Preparativa del CNR, Corso Stati Uniti, 4, 35020 Camin, Padova (IT))

    1991-09-01

    This paper discusses the Fe{sup 3+} reduction reaction studied at Pt and polyaniline rotating disk electrodes by steady-state and impedance methods with the aim of testing the possibility of achieving the charge transfer resistance (R{sub ts}) of a redox reaction mediated by a conducting polymer film by ac impedance R{sub ts} was obtained as a function of electrode potential and rotation rate by nonlinear least squares fitting of a previously developed kinetic equation to the experimental data. These R{sub ts} values were combined with steady-state ones to calculate b{sub c} and k{sup 0}.

  13. Impedance of accelerator components

    International Nuclear Information System (INIS)

    Corlett, J.N.

    1996-05-01

    As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q = 1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed

  14. A new method to assess skin treatments for lowering the impedance and noise of individual gelled Ag–AgCl electrodes

    International Nuclear Information System (INIS)

    Piervirgili, G; Petracca, F; Merletti, R

    2014-01-01

    A model-based new procedure for measuring the single electrode–gel–skin impedance (Z EGS ) is presented. The method is suitable for monitoring the contact impedance of the electrodes of a large array with limited modifications of the hardware and without removing or disconnecting the array from the amplifier. The procedure is based on multiple measurements between electrode pairs and is particularly suitable for electrode arrays. It has been applied to study the effectiveness of three skin treatments, with respect to no treatment, for reducing the electrode–gel–skin impedance (Z EGS ) and noise: (i) rubbing with alcohol; (ii) rubbing with abrasive conductive paste; (iii) stripping with adhesive tape. The complex impedances Z EGS of the individual electrodes were measured by applying this procedure to disposable commercial Ag–AgCl gelled electrode arrays (4  ×  1) with a 5 mm 2 contact area. The impedance unbalance ΔZ = Z EGS1  − Z EGS2 and the RMS noise (V RMS ) were measured between pairs of electrodes. The tissue impedance Z T was also obtained, as a collateral result. Measurements were repeated at t 0 = 0 min and at t 30 = 30 min from the electrode application. Mixed linear models and linear regression analysis applied to Z EGS , ΔZ and noise V RMS for the skin treatment factor demonstrated (a) that skin rubbing with abrasive conductive paste is more effective in lowering Z EGS , ΔZ and V RMS (p < 0.01) than the other treatments or no treatment, and (b) a statistically significant decrement (p < 0.01), between t 0 and t 30 , of magnitude and phase of Z EGS . Rubbing with abrasive conductive paste significantly decreased the noise V RMS with respect to other treatments or no treatment. (paper)

  15. A new method to assess skin treatments for lowering the impedance and noise of individual gelled Ag-AgCl electrodes.

    Science.gov (United States)

    Piervirgili, G; Petracca, F; Merletti, R

    2014-10-01

    A model-based new procedure for measuring the single electrode-gel-skin impedance (ZEGS) is presented. The method is suitable for monitoring the contact impedance of the electrodes of a large array with limited modifications of the hardware and without removing or disconnecting the array from the amplifier. The procedure is based on multiple measurements between electrode pairs and is particularly suitable for electrode arrays. It has been applied to study the effectiveness of three skin treatments, with respect to no treatment, for reducing the electrode-gel-skin impedance (ZEGS) and noise: (i) rubbing with alcohol; (ii) rubbing with abrasive conductive paste; (iii) stripping with adhesive tape. The complex impedances ZEGS of the individual electrodes were measured by applying this procedure to disposable commercial Ag-AgCl gelled electrode arrays (4  ×  1) with a 5 mm(2) contact area. The impedance unbalance ΔZ = ZEGS1 - ZEGS2 and the RMS noise (VRMS) were measured between pairs of electrodes. The tissue impedance ZT was also obtained, as a collateral result. Measurements were repeated at t0 = 0 min and at t30 = 30 min from the electrode application. Mixed linear models and linear regression analysis applied to ZEGS, ΔZ and noise VRMS for the skin treatment factor demonstrated (a) that skin rubbing with abrasive conductive paste is more effective in lowering ZEGS, ΔZ and VRMS (p decrement (p < 0.01), between t0 and t30, of magnitude and phase of ZEGS.Rubbing with abrasive conductive paste significantly decreased the noise VRMS with respect to other treatments or no treatment.

  16. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...

  17. Impedance models in time domain

    NARCIS (Netherlands)

    Rienstra, S.W.

    2005-01-01

    Necessary conditions for an impedance function are derived. Methods available in the literature are discussed. A format with recipe is proposed for an exact impedance condition in time domain on a time grid, based on the Helmholtz resonator model. An explicit solution is given of a pulse reflecting

  18. Characterization of full set material constants of piezoelectric materials based on ultrasonic method and inverse impedance spectroscopy using only one sample.

    Science.gov (United States)

    Li, Shiyang; Zheng, Limei; Jiang, Wenhua; Sahul, Raffi; Gopalan, Venkatraman; Cao, Wenwu

    2013-09-14

    The most difficult task in the characterization of complete set material properties for piezoelectric materials is self-consistency. Because there are many independent elastic, dielectric, and piezoelectric constants, several samples are needed to obtain the full set constants. Property variation from sample to sample often makes the obtained data set lack of self-consistency. Here, we present a method, based on pulse-echo ultrasound and inverse impedance spectroscopy, to precisely determine the full set physical properties of piezoelectric materials using only one small sample, which eliminated the sample to sample variation problem to guarantee self-consistency. The method has been applied to characterize the [001] C poled Mn modified 0.27Pb(In 1/2 Nb 1/2 )O 3 -0.46Pb(Mg 1/3 Nb 2/3 )O 3 -0.27PbTiO 3 single crystal and the validity of the measured data is confirmed by a previously established method. For the inverse calculations using impedance spectrum, the stability of reconstructed results is analyzed by fluctuation analysis of input data. In contrast to conventional regression methods, our method here takes the full advantage of both ultrasonic and inverse impedance spectroscopy methods to extract all constants from only one small sample. The method provides a powerful tool for assisting novel piezoelectric materials of small size and for generating needed input data sets for device designs using finite element simulations.

  19. Phase angle as bioelectrical marker to identify elderly patients at risk of sarcopenia.

    Science.gov (United States)

    Basile, Claudia; Della-Morte, David; Cacciatore, Francesco; Gargiulo, Gaetano; Galizia, Gianluigi; Roselli, Mario; Curcio, Francesco; Bonaduce, Domenico; Abete, Pasquale

    2014-10-01

    Several markers have been associated with sarcopenia in the elderly, including bioelectrical indices. Phase angle (PhA) is an impedance parameter and it has been suggested as an indicator of cellular death. Thus, the relationship between PhA and muscle mass and strength was investigated in 207 consecutively elderly participants (mean age 76.2±6.7years) admitted for multidimensional geriatric evaluation. Muscle strength by grip strength using a hand-held dynamometer and muscle mass was measured by bioimpedentiometer. PhA was calculated directly with its arctangent (resistance/reactance×180°/π). Linear relationship among muscular mass and strength and with clinical and biochemical parameters, including PhA at uni- and multivariate analysis were performed. Linear regression analysis demonstrated that lower level of PhA is associated with reduction in grip strength (y=3.16+0.08x; r=0.49; pelderly subjects and it may be considered a good bioelectrical marker to identify elderly patients at risk of sarcopenia. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Electrical impedance spectroscopy for quality assessment of meat and fish: A review on basic principles, measurement methods, and recent advances

    Science.gov (United States)

    Electrical impedance spectroscopy (EIS), as an effective analytical technique for electrochemical system, has shown a wide application for food quality and safety assessment recently. Individual differences of livestock cause high variation in quality of raw meat and fish and their commercialized pr...

  1. An impedance method for spatial sensing of 3D cell constructs – towards applications in tissue engineering

    DEFF Research Database (Denmark)

    Canali, Chiara; Mazzoni, Chiara; Larsen, Layla Bashir

    2015-01-01

    ) cells were encapsulated in gelatin to form artificial 3D cell constructs and detected when placed in different positions inside large gelatin scaffolds. Taken together, these results open new perspectives for impedance-based sensing technologies for non-invasive monitoring in tissue engineering...

  2. A new method to compensate impedance artefacts for Li-ion batteries with integrated micro-reference electrodes

    NARCIS (Netherlands)

    Raijmakers, L.H.J.; Notten, P.H.L.; Lammers, M.J.G.

    2017-01-01

    In order to measure the electrochemical characteristics of both electrodes inside Li-ion batteries, micro-reference electrodes (μREF) turned out to be very useful. However, measuring the electrochemical impedance with respect to μREF can lead to severe measurement artefacts, making a detailed

  3. A comparison and accuracy analysis of impedance-based temperature estimation methods for Li-ion batteries

    NARCIS (Netherlands)

    Beelen, H.P.G.J.; Raijmakers, L.H.J.; Donkers, M.C.F.; Notten, P.H.L.; Bergveld, H.J.

    2016-01-01

    In order to guarantee safe and proper use of Lithium-ion batteries during operation, an accurate estimate of the battery temperature is of paramount importance. Electrochemical Impedance Spectroscopy (EIS) can be used to estimate the battery temperature and several EIS-based temperature estimation

  4. Brain bioelectrical activity changes in patients with poststroke depression and apathy

    Directory of Open Access Journals (Sweden)

    I. V. Kichuk

    2015-01-01

    Full Text Available Objective: to study the specific features of brain bioelectrical activity in patents with poststroke apathy and depressive disorders.Patients and methods. The investigation enrolled 175 patients (84 men and 91 women with new-onset cerebral stroke at different sites. A total of 107 (61% patients of them were observed to have depressive disorders (n=41 (38% and apathy (n=66 (62% within a year after disease onset. A control group included 68 (39% patients without poststroke affective disorders. The mean age of the study group patients was 66±10 years and that of the control patients was 68±11 years. The severity and magnitude of neurological deficit were evaluated using the U.S. National Institutes of Health Stroke Scale (NIHSS. The patients underwent electroencephalography (EEG, brain computed tomography and magnetic resonance imaging. The investigators used diagnostic and statistical manual of mental disorders (DSM-IV criteria to diagnose depression and the Hamilton depression rating scale (HAM-D and the mini-mental status examination (MMSE to evaluate the mental status. The basic rhythmic power indices in the affected and unaffected hemispheres were calculated, as well as anteroposterior alpha rhythm distribution coefficient and interhemispheric asymmetry coefficient. Results and discussion. The computer EEG analysis was shown to identify the hallmark characteristics of brain bioelectric activity in patients with different types of affective disorders in the acute, early and late recovery periods of stroke. The patients with affective disorders were found to have brain bioelectrical activity changes predominantly in the rapid frequency sub-band on EEG, suggesting midbrain structural dysfunction. In the patients with poststroke depression, depressive disorder scale scores were related to the power of bioelectric activity in the slow and alpha frequency bands manly in the acute stroke period whereas those were correlated with the EEG

  5. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  6. Determination of the ionic transport numbers of lanthanum gallate materials by impedance spectroscopy and modified EMF method

    Directory of Open Access Journals (Sweden)

    Peña-Martínez, J.

    2008-06-01

    Full Text Available A combination of impedance spectroscopy and a modified electromotive force method (emf were used to evaluate the ionic transport numbers and the overall conductivity of several doped lanthanum gallate materials, i.e. La0.9Sr0.1Ga1-xMgxO3-δ (x=0.05-0.30, La0.9A0.1Ga0.8Mg0.2O3-δ (A=Sr, Ba and Ca and La0.9Sr0.1Ga0.8Mg0.2-yCoyO3-δ (y=0.015 and 0.045. La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM sample showed the maximum ionic transport number in the temperature range 900-1173 K, around 0.99 in both O2/air and H2/air gradients.

    La conductividad total y los números de transporte iónico de las composiciones, basadas en el galato de lantano, La0,9Sr0,1Ga1-xMgxO3-δ (x=0,05-0,30, La0,9A0,1Ga0,8Mg0,2O3-δ (A=Sr, Ba, Ca y La0,9Sr0,1Ga0,8Mg0,2-yCoyO3-δ (y=0.015; 0,045 fueron estudiadas mediante una combinación de técnicas de espectroscopia de impedancia compleja y fuerza electromotriz (fem. La composición La0,9Sr0,1Ga0,8Mg0,2O2,85 (LSGM presenta el mayor número de transporte iónico, concretamente 0,99 en el rango de temperaturas 900-1173 K, tanto en gradiente de O2/aire como de H2/aire.

  7. Integrated assessment of bioelectricity technology options

    International Nuclear Information System (INIS)

    Thornley, Patricia; Upham, Paul; Huang, Ye; Rezvani, Sina; Brammer, John; Rogers, John

    2009-01-01

    Power generation from biomass is a sustainable energy technology which can contribute to substantial reductions in greenhouse gas emissions, but with greater potential for environmental, economic and social impacts than most other renewable energy technologies. It is important therefore in assessing bioenergy systems to take account of not only technical, but also environmental, economic and social parameters on a common basis. This work addresses the challenge of analysing, quantifying and comparing these factors for bioenergy power generation systems. A life-cycle approach is used to analyse the technical, environmental, economic and social impacts of entire bioelectricity systems, with a number of life-cycle indicators as outputs to facilitate cross-comparison. The results show that similar greenhouse gas savings are achieved with the wide variety of technologies and scales studied, but land-use efficiency of greenhouse gas savings and specific airborne emissions varied substantially. Also, while specific investment costs and electricity costs vary substantially from one system to another the number of jobs created per unit of electricity delivered remains roughly constant. Recorded views of stakeholders illustrate that diverging priorities exist for different stakeholder groups and this will influence appropriate choice of bioenergy systems for different applications

  8. Cyclic voltammetry, square wave voltammetry, electrochemical impedance spectroscopy and colorimetric method for hydrogen peroxide detection based on chitosan/silver nanocomposite

    Directory of Open Access Journals (Sweden)

    Hoang V. Tran

    2018-05-01

    Full Text Available In this paper, we demonstrate a promising method to fabricate a non-enzymatic stable, highly sensitive and selective hydrogen peroxide sensor based on a chitosan/silver nanoparticles (CS/AgNPs hybrid. Using this composite, we elaborated both electrochemical and colorimetric sensors for hydrogen peroxide detection. The colorimetric sensor is based on a homogenous reaction which fades the color of CS/AgNPs solutions from red-orange to colorless depending on hydrogen peroxide concentration. For the electrochemical sensor, CS/AgNPs were immobilized on glassy carbon electrodes and hydrogen peroxide was measured using cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy. The response time is less than 10 s and the detection limit is 5 μM. Keywords: Spectrophotometric detection, Electrochemical impedance spectroscopy, Square wave voltammetry, Cyclic voltammetry, Chitosan/silver nanoparticles (CS/AgNPs hybrid, Hydrogen peroxide

  9. Bioelectricity Production from Microalgae-Microbial Fuel Cell Technology (MMFC

    Directory of Open Access Journals (Sweden)

    da Costa Carlito

    2018-01-01

    Full Text Available Microbial fuel cell is an ecological innovative technology producing bioelectricity by utilizing microbes activity. Substituent energy is produced by changing the chemical energy to electrical energy through the catalytic reaction of microorganism. The research aims to find out the potency of bioelectricity produced by microalgae microbial fuel cell technology by utilizing the combination of tapioca wastewater and microalgae cultivation. This research is conducted through the ingredients preparation stage – microalgae culture, wastewater characterization, membrane and graphite activation, and the providing of other supporting equipment. The next stage is the MMFC arrangement, while the last one is bioelectricity measurement. The result of optimal bioelectricity production on the comparison of electrode 2 : 2, the power density is 44,33 mW/m2 on day 6, meanwhile, on that of 1 : 1, 20,18 mW/m2 power density on day 1 is obtained. It shows that bioelectricity can be produced from the combination of tapioca wastewater and microalgae culture through the microalgae-microbial fuel cell (MMFC technology.This research is expected to be a reference for the next research particularly the one that observes the utilizing of microalgae as the part of new and renewable energy sources.

  10. Advances In Impedance Theory

    International Nuclear Information System (INIS)

    Stupakov, G.

    2009-01-01

    We review recent progress in the following areas of the impedance theory: calculation of impedance of tapers and small angle collimators; optical approximation and parabolic equation for the high-frequency impedance; impedance due to resistive inserts in a perfectly conducting pipe.

  11. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  12. Biomass production and control of nutrient leaching of willows using different planting methods with special emphasis on an appraisal of the electrical impedance for roots

    Energy Technology Data Exchange (ETDEWEB)

    Yang Cao

    2011-07-01

    Willow reproduction can be achieved through vertically or horizontally planted cuttings. Conventionally, plantations are established by inserting cuttings vertically into the soil. There is, however, a lack of information about the biomass production and nutrient leaching of plantations established through horizontally planted cuttings. A greenhouse experiment and a field trial were carried out to investigate whether horizontally planted Salix schwerinii cuttings have a positive effect on stem yield, root distribution and nutrient leaching in comparison with vertically planted cuttings with different planting densities. The shoots' height of horizontally planted cuttings was significantly smaller than that of vertically planted cuttings during the first two weeks after planting in the pot experiment. Thereafter, no significant effect of planting orientation on the stem biomass was observed in the two conducted experiments. In both experiments the total stem biomass increased with the planting density. It was also found that the fine root biomass and the specific root length were not affected by the planting orientation or density, while the fine root surface area and the absorbing root surface area (ARSA) were affected only by the planting density. The planting orientation did not affect the nutrient concentrations in the soil leachate, apart from SO{sub 4}-S and PO{sub 4}-P in the pot experiment. The ARSA in the pot experiment was assessed by using the earth impedance method. The applicability of this method was evaluated in a hydroponic study of willow cuttings where root and stem were measured independently. Electrical resistance had a good correlation with the contact area of the roots with the solution. However, the resistance depended strongly on the contact area of the stem with the solution, which caused a bias in the evaluation of root surface area. A similar experimental set-up with electrical impedance spectroscopy was employed to study the

  13. Comparison of Modified Impedance Whole Blood Platelet Aggregation Method Detecting Platelet Function in ACS Patients with Different CYP2C19 Genotypes.

    Science.gov (United States)

    Cui, Chanjuan; Qiao, Rui; Zhang, Jie

    2016-01-01

    A reliable laboratory test to monitor onclopidogrel platelet reactivity (PR) is very necessary. In addition, genetic factors also play an important part in onclopidogrel PR. This study aimed to modify the original impedance whole blood platelet aggregation assay associated with the release assay to monitor onclopidogrel PR and assess their relationship with genotype. We adjusted the concentration of calcium in the in vitro reaction system of platelet aggregation to modify the original impedance whole blood platelet aggregation assay. Meanwhile, chronolume, which quantified the adenosine triphosphate (ATP) released from platelet dense granules, is added to this reaction system to reflect the platelet release function. In the modified assay, platelet magnified activation time (MAT) and the maximal platelet ATP release value (RV) were used to reflect platelet function parameters. In the original assay, the electrical resistance (omega) and RV were used to reflect platelet function parameters. Onclopidogrel PR was detected by the original impedance whole blood platelet aggregation assay, modified assay, and flow cytometric vasodilator stimulated phosphoprotein (VASP) assay in 168 patients with acute coronary syndromes (ACS). CYP2C19*2 and CYP2C19*3 polymorphisms were also detected in all of these patients. This modified method showed that when 12.5 microL CaCl2 (0.2 mmol/L) was added to the reaction system, MAT was appropriate (93 +/- 23 seconds). The CVs for the modified impedance assay and release assay were 9.31% and 6.13%, respectively. The mean VASP-PRI in the patient group treated with clopidogrel was significantly lower than that in the control group without antiplatelet therapy (54.88 +/- 16.81% vs. 79.86 +/- 10.24%, p 50% group were shorter than that in the PRI 50% group were higher than that in the PRI omega) and RV of the original method showed no differences between the two groups [0 (0-2) vs. 0 (0-1.25), 0.05 (0-0.25) vs. 0.08 (0-0.24); p > 0.05, p > 0

  14. Diaphragm flange and method for lowering particle beam impedance at connected beam tubes of a particle accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Biallas, George Herman

    2017-07-04

    A diaphragm flange for connecting the tubes in a particle accelerator while minimizing beamline impedance. The diaphragm flange includes an outer flange and a thin diaphragm integral with the outer flange. Bolt holes in the outer flange provide a means for bolting the diaphragm flange to an adjacent flange or beam tube having a mating bolt-hole pattern. The diaphragm flange includes a first surface for connection to the tube of a particle accelerator beamline and a second surface for connection to a CF flange. The second surface includes a recessed surface therein and a knife-edge on the recessed surface. The diaphragm includes a thickness that enables flexing of the integral diaphragm during assembly of beamline components. The knife-edge enables compression of a soft metal gasket to provide a leak-tight seal.

  15. Bioelectrical impedance analysis (BIA) for sarcopenic obesity (SO) diagnosis in young female subjects

    International Nuclear Information System (INIS)

    González-Correa, C H; Caicedo-Eraso, J C; Villada-Gomez J S

    2013-01-01

    Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α 2 = 0.094, 0.037 and 0.275 respectively) it was observed a tendency for HGS, HST and SMI deterioration when %BF increases. However, other confounding factors must be investigated. Probably as the population gets more obese, the problematic of SO will be found earlier in life.

  16. Biochemical and anthropometric correlates of bio-electrical impedance parameters in severely malnourished children

    DEFF Research Database (Denmark)

    Girma, Tsinuel; Nielsen, Anne-Louise Hother; Kæstel, Pernille

    2018-01-01

    established using forward selection after comparing models using likelihood ratio test. RESULTS: The sample comprised 55 children with SAM (age 36 ± 24 months; 60% males; 72.7% oedematous) and 80 healthy control children (age 28 ± 15 months; 47.5% males). Oedematous children had the lowest BI parameters...

  17. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2014-07-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  18. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2012-01-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  19. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    OpenAIRE

    M. V. Konovalova; A. V. Anisimova; A. Yu. Vashura; E. Z. Godina; D. V. Nikolaev; S. G. Rudnev; O. A. Starunova; I. A. Khomyakova; G. Ya. Tseytlin

    2012-01-01

    The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years) and of age-matched healthy controls (n = 1,500) show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell...

  20. Sensitivity field distributions for segmental bioelectrical impedance analysis based on real human anatomy

    International Nuclear Information System (INIS)

    Danilov, A A; Rudnev, S G; V Vassilevski, Yu; Kramarenko, V K; Nikolaev, D V; Smirnov, A V; Salamatova, V Yu

    2013-01-01

    In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.

  1. Sensitivity field distributions for segmental bioelectrical impedance analysis based on real human anatomy

    Science.gov (United States)

    Danilov, A. A.; Kramarenko, V. K.; Nikolaev, D. V.; Rudnev, S. G.; Salamatova, V. Yu; Smirnov, A. V.; Vassilevski, Yu V.

    2013-04-01

    In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.

  2. Feasibility of bioelectrical impedance analysis in children with a severe generalized cerebral palsy

    NARCIS (Netherlands)

    R.J.G. Veugelers (Rebekka); C. Penning (Corine); L. van Gulik (Laura); D. Tibboel (Dick); H.M. Evenhuis (Heleen)

    2006-01-01

    textabstractObjective: The need is strong for an accurate and easy-to-perform test to evaluate the nutritional state of children who have a severe generalized cerebral palsy, defined as a severe motor handicap and an intellectual disability. For that purpose, we determined the feasibility of

  3. Electrical impedance spectroscopy (EIS)-based evaluation of biological tissue phantoms to study multifrequency electrical impedance tomography (Mf-EIT) systems

    KAUST Repository

    Bera, Tushar Kanti

    2016-03-18

    Abstract: Electrical impedance tomography (EIT) phantoms are essential for the calibration, comparison and evaluation of the EIT systems. In EIT, the practical phantoms are typically developed based on inhomogeneities surrounded by a homogeneous background to simulate a suitable conductivity contrast. In multifrequency EIT (Mf-EIT) evaluation, the phantoms must be developed with the materials which have recognizable or distinguishable impedance variations over a wide range of frequencies. In this direction the impedance responses of the saline solution (background) and a number vegetable and fruit tissues (inhomogeneities) are studied with electrical impedance spectroscopy (EIS) and the frequency responses of bioelectrical impedance and conductivity are analyzed. A number of practical phantoms with different tissue inhomogeneities and different inhomogeneity configurations are developed and the multifrequency impedance imaging is studied with the Mf-EIT system to evaluate the phantoms. The conductivity of the vegetable inhomogeneities reconstructed from the EIT imaging is compared with the conductivity values obtained from the EIS studies. Experimental results obtained from multifrequency EIT reconstruction demonstrate that the electrical impedance of all the biological tissues inhomogenity decreases with frequency. The potato tissue phantom produces better impedance image in high frequency ranges compared to the cucumber phantom, because the cucumber impedance at high frequency becomes lesser than that of the potato at the same frequency range. Graphical Abstract: [Figure not available: see fulltext.] © 2016 The Visualization Society of Japan

  4. Compost in plant microbial fuel cell for bioelectricity generation

    NARCIS (Netherlands)

    Moqsud, M.A.; Yoshitake, J.; Bushra, Q.S.; Hyodo, M.; Omine, K.; Strik, D.P.B.T.B.

    2015-01-01

    Recycling of organic waste is an important topic in developing countries as well as developed countries. Compost from organic waste has been used for soil conditioner. In this study, an experiment has been carried out to produce green energy (bioelectricity) by using paddy plant microbial fuel cells

  5. Bioelectric Control of a 757 Class High Fidelity Aircraft Simulation

    Science.gov (United States)

    Jorgensen, Charles; Wheeler, Kevin; Stepniewski, Slawomir; Norvig, Peter (Technical Monitor)

    2000-01-01

    This paper presents results of a recent experiment in fine grain Electromyographic (EMG) signal recognition, We demonstrate bioelectric flight control of 757 class simulation aircraft landing at San Francisco International Airport. The physical instrumentality of a pilot control stick is not used. A pilot closes a fist in empty air and performs control movements which are captured by a dry electrode array on the arm, analyzed and routed through a flight director permitting full pilot outer loop control of the simulation. A Vision Dome immersive display is used to create a VR world for the aircraft body mechanics and flight changes to pilot movements. Inner loop surfaces and differential aircraft thrust is controlled using a hybrid neural network architecture that combines a damage adaptive controller (Jorgensen 1998, Totah 1998) with a propulsion only based control system (Bull & Kaneshige 1997). Thus the 757 aircraft is not only being flown bioelectrically at the pilot level but also demonstrates damage adaptive neural network control permitting adaptation to severe changes in the physical flight characteristics of the aircraft at the inner loop level. To compensate for accident scenarios, the aircraft uses remaining control surface authority and differential thrust from the engines. To the best of our knowledge this is the first time real time bioelectric fine-grained control, differential thrust based control, and neural network damage adaptive control have been integrated into a single flight demonstration. The paper describes the EMG pattern recognition system and the bioelectric pattern recognition methodology.

  6. A current-excited triple-time-voltage oversampling method for bio-impedance model for cost-efficient circuit system.

    Science.gov (United States)

    Yan Hong; Yong Wang; Wang Ling Goh; Yuan Gao; Lei Yao

    2015-08-01

    This paper presents a mathematic method and a cost-efficient circuit to measure the value of each component of the bio-impedance model at electrode-electrolyte interface. The proposed current excited triple-time-voltage oversampling (TTVO) method deduces the component values by solving triple simultaneous electric equation (TSEE) at different time nodes during a current excitation, which are the voltage functions of time. The proposed triple simultaneous electric equations (TSEEs) allows random selections of the time nodes, hence numerous solutions can be obtained during a single current excitation. Following that, the oversampling approach is engaged by averaging all solutions of multiple TSEEs acquired after a single current excitation, which increases the practical measurement accuracy through the improvement of the signal-to-noise ratio (SNR). In addition, a print circuit board (PCB) that consists a switched current exciter and an analog-to-digital converter (ADC) is designed for signal acquisition. This presents a great cost reduction when compared against other instrument-based measurement data reported [1]. Through testing, the measured values of this work is proven to be in superb agreements on the true component values of the electrode-electrolyte interface model. This work is most suited and also useful for biological and biomedical applications, to perform tasks such as stimulations, recordings, impedance characterizations, etc.

  7. Impedance spectroscopy and morphology of SrBi{sub 4}Ti{sub 4}O{sub 15} ceramics prepared by soft chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Rout, S.K. [Department of Chemical and Biomolecular Engineering, KAIST (Korea, Republic of); Department of Applied Physics, BIT, Mesra, Ranchi (India)], E-mail: drskrout@gmail.com; Hussian, Ali; Lee, J.S. [School of Materials Science and Engineering University of Ulsan (Korea, Republic of); Kim, I.W. [Department of Physics, University of Ulsan (Korea, Republic of); Woo, S.I. [Department of Chemical and Biomolecular Engineering, KAIST (Korea, Republic of)], E-mail: siwoo@kaist.ac.kr

    2009-05-27

    In this work, we have synthesized polycrystalline SrBi{sub 4}Ti{sub 4}O{sub 15} (SBiT) ceramics by soft chemical method. These ceramics were structurally characterized by analysis of X-ray diffraction (XRD) patterns, indicates that SBiT ceramics present an orthorhombic structure. Scanning electron micrograph shows that the grains exhibit a plate like morphology. Dielectric relaxations of the SBiT ceramics were investigated in the temperature range 100-700 deg. C. Using the Cole-Cole model, an analysis of the dielectric loss with frequency was performed, assuming a distribution of relaxation time. The presence of the peaks in temperature dependent dielectric loss indicates that the hoping of charge carriers is responsible for the relaxation. Impedance studies shows a non-Debye type relaxation, and relaxation frequency shift to higher side with increase in temperature. A significant shift in impedance loss peaks towards higher frequency side indicates conduction in material and favoring the long range motion of mobile charge carriers. The Nyquist plot shows overlapping semicircles, for grain and grain boundary of SBiT ceramics. The frequency dependent ac conductivity at different temperatures indicates that the conduction process is thermally activated process and the spectra follow the universal power law. The hopping frequency shifts towards higher frequency side with increase of temperature, below which the conductivity is frequency independent. The variation of dc conductivity confirms that the SBiT ceramics exhibits negative temperature coefficient of resistance behavior in high temperature.

  8. Method for inverting reflection trace data from 3-D and 4-D seismic surveys and identifying subsurface fluid and pathways in and among hydrocarbon reservoirs based on impedance models

    Science.gov (United States)

    He, W.; Anderson, R.N.

    1998-08-25

    A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management. 20 figs.

  9. A short tutorial contribution to impedance and AC-electrokinetic characterization and manipulation of cells and media: Are electric methods more versatile than acoustic and laser methods?

    Directory of Open Access Journals (Sweden)

    Jan Gimsa

    2014-11-01

    Full Text Available Lab-on-chip systems (LOCs can be used as in vitro systems for cell culture or manipulation in order to analyze or monitor physiological cell parameters. LOCs may combine microfluidic structures with integrated elements such as piezo-transducers, optical tweezers or electrodes for AC-electrokinetic cell and media manipulations. The wide frequency band (<1 kHz to >1 GHz usable for AC-electrokinetic manipulation and characterization permits avoiding electrochemical electrode processes, undesired cell damage, and provides a choice between different polarization effects that permit a high electric contrast between the cells and the external medium as well as the differentiation between cellular subpopulations according to a variety of parameters. It has been shown that structural polarization effects do not only determine the impedance of cell suspensions and the force effects in AC-electrokinetics but can also be used for the manipulation of media with inhomogeneous temperature distributions. This manuscript considers the interrelations of the impedance of suspensions of cells and AC-electrokinetic single cell effects, such as electroorientation, electrodeformation, dielectrophoresis, electrorotation, and travelling wave (TW dielectrophoresis. Unified models have allowed us to derive new characteristic equations for the impedance of a suspension of spherical cells, TW dielectrophoresis, and TW pumping. A critical review of the working principles of electro-osmotic, TW and electrothermal micropumps shows the superiority of the electrothermal pumps. Finally, examples are shown for LOC elements that can be produced as metallic structures on glass chips, which may form the bottom plate for self-sealing microfluidic systems. The structures can be used for cell characterization and manipulation but also to realize micropumps or sensors for pH, metabolites, cell-adhesion, etc.

  10. Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yuanwen; Carvalho-de-Souza, João L.; Wong, Raymond C. S.; Luo, Zhiqiang; Isheim, Dieter; Zuo, Xiaobing; Nicholls, Alan W.; Jung, Il Woong; Yue, Jiping; Liu, Di-Jia; Wang, Yucai; De Andrade, Vincent; Xiao, Xianghui; Navrazhnykh, Luizetta; Weiss, Dara E.; Wu, Xiaoyang; Seidman, David N.; Bezanilla, Francisco; Tian, Bozhi

    2016-06-27

    Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multi-scale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical vapour deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework and random submicrometre voids, and shows an average Young’s modulus that is 2–3 orders of magnitude smaller than that of single-crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permits non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems.

  11. Nonsynchronous Noncommensurate Impedance Transformers

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, K

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of two types of transmission lines: transmission lines with a characteristic impedance equal to the impedance of the source, and transmission lines with a characteristic impedance equal to the load. The practical...... advantage of such transformers is that they can be constructed using sections of transmission lines with a limited variety of characteristic impedances. These transformers also provide comparatively compact size in applications where a wide transformation ratio is required. This paper presents the data...... matrix approach and experimentally verified by synthesizing a 12-section nonsynchronous noncommensurate impedance transformer. The measured characteristics of the transformer are compared to the characteristics of a conventional tapered line transformer....

  12. A novel human-machine interface based on recognition of multi-channel facial bioelectric signals

    International Nuclear Information System (INIS)

    Razazadeh, Iman Mohammad; Firoozabadi, S. Mohammad; Golpayegani, S.M.R.H.; Hu, H.

    2011-01-01

    Full text: This paper presents a novel human-machine interface for disabled people to interact with assistive systems for a better quality of life. It is based on multichannel forehead bioelectric signals acquired by placing three pairs of electrodes (physical channels) on the Fron-tails and Temporalis facial muscles. The acquired signals are passes through a parallel filter bank to explore three different sub-bands related to facial electromyogram, electrooculogram and electroencephalogram. The root mean features of the bioelectric signals analyzed within non-overlapping 256 ms windows were extracted. The subtractive fuzzy c-means clustering method (SFCM) was applied to segment the feature space and generate initial fuzzy based Takagi-Sugeno rules. Then, an adaptive neuro-fuzzy inference system is exploited to tune up the premises and consequence parameters of the extracted SFCMs. rules. The average classifier discriminating ratio for eight different facial gestures (smiling, frowning, pulling up left/right lips corner, eye movement to left/right/up/down is between 93.04% and 96.99% according to different combinations and fusions of logical features. Experimental results show that the proposed interface has a high degree of accuracy and robustness for discrimination of 8 fundamental facial gestures. Some potential and further capabilities of our approach in human-machine interfaces are also discussed. (author)

  13. Registration and Analysis of Bioelectric Activity of Sensory-Motor Cortex During the Electrical Stimulation of Nucleus Caudate in Rats

    Directory of Open Access Journals (Sweden)

    Snežana Medenica-Milanović

    2007-05-01

    Full Text Available Background and purposeThe caudate circuit takes part in cognitive control of motor activity The purpose of the present work was registration and analysis of basic bioelectrical activity of ventral and dorsal sensory-motor cortex and nucleus caudate, study of the changes in EEG after nucleus caudate electrical stimulation and to identify of threshold level of electrical stimuli responsible for changes of electrical activity in registered brain area.Materials and methodsWe used 28 albino Wistar rat of both genders. After the animal fixation on stereotaxic apparatus to dry bone, the places for electrode fixation were marked. Two days after the electrodes had been implanted an EEG was registered so that the animals would adjust to the conditions and so they would repair the tissue reactions. EEG was registered with bipolar electrodes with ten-channeled apparatus. For first half an hour spontaneous activity of the brain was registered, and after that the head of nucleus caudate was stimulated with altered impulses of various voltages, frequency and duration.Results and conclusionsThreshold values of electric stimulus intensity from 3 to 5 V, frequency from 3 to 5 Hz, duration from 3 to 5 ms, by stimulation the head of nucleus caudate of rat, lead to the change of basal bioelectric activity of cerebrum. The change of bioelectric activity is firstly recorded in equilateral cortex, and with the higher intensity of the stimulus the changes overtake the contra lateral cortex.

  14. FDTD modeling of thin impedance sheets

    Science.gov (United States)

    Luebbers, Raymond J.; Kunz, Karl S.

    1991-01-01

    Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. In this paper it is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods.

  15. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa; Salama, Khaled N.; Shamim, Atif

    2014-01-01

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha

  16. Impedance of a nanoantenna

    International Nuclear Information System (INIS)

    Greffet, Jean-Jacques; Laroche, Marine; Marquier, Francois

    2009-01-01

    We introduce a generalized definition of the impedance of a nanoantenna that can be applied to any system. We also introduce a definition of the impedance of a two level system. Using this framework, we establish a link between the electrical engineering and the quantum optics picture of light emission.

  17. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  18. [Evaluation of nutritional Status in lung cancer using bio electrical impedance analysis and mini nutritional assessment].

    Science.gov (United States)

    Daghfous, Hafaoua; El Ayeb, Wejdène; Alouane, Leila; Tritar, Fatma

    2014-12-01

    Malnutrition and cachexia were a frequent problem in lung cancer and increases the risks of morbidity and mortality in these patients. Bioelectrical impedance analysis (BIA) is easy, non-invasive and reproducible method that can be performed. Evaluate nutritional status in patients with primary lung cancer by Mini Nutritional Assessment (MNA), BIA and anthropometric values (weight, arm and calf circumferences) and correlate the nutritional parameters to severity of cancer and histopathology. The nutritional status of 73 cases of primary lung cancer was evaluated by anthropometric parameters, MNA test and impedencemetrie Results: According to body mass index (BMI), malnutrition, overweight and obesity were noted in 34,2%, 13,7% and 5,5%. According to BMI, free-fat mass index (FFMI) and fat mass index (FMI), the investigations occurred malnutrition and depletion of muscle in respectively 19,2% and 23,3% of cases. Fat depletion was noted in 21,9%. Overweight and obesity were detected in 6,8% and 5,5% of cases. Assessment by MNA, revealed that 28,7% of patients were already malnourished and 49,3% of patients were at risk of malnutrition. A significant correlation existed between the score of MNA and arm and calf circumferences, FFMI and FMI. FMI was significantly lower in group of patients with small lung carcinoma. Only FFMI allows early detection of malnutrition in cancer patients overestimated by measuring BMI and arm circumference was the better indicator of depletion of muscle.

  19. Electrochemical Impedance Spectroscopy in Solid State Ionics: Recent Advances

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    2004-01-01

    Electrochemical Impedance Spectroscopy (EIS) has become an important research tool in Solid State Ionics. Some new developments are highlighted: new methods of automatic parameter extraction from impedance measurements are briefly discussed. The Kramers–Kronig data validation test presents another

  20. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  1. Compensating for evanescent modes and estimating characteristic impedance in waveguide acoustic impedance measurements

    DEFF Research Database (Denmark)

    Nørgaard, Kren Rahbek; Fernandez Grande, Efren

    2017-01-01

    The ear-canal acoustic impedance and reflectance are useful for assessing conductive hearing disorders and calibrating stimulus levels in situ. However, such probe-based measurements are affected by errors due to the presence of evanescent modes and incorrect estimates or assumptions regarding...... characteristic impedance. This paper proposes a method to compensate for evanescent modes in measurements of acoustic impedance, reflectance, and sound pressure in waveguides, as well as estimating the characteristic impedance immediately in front of the probe. This is achieved by adjusting the characteristic...... impedance and subtracting an acoustic inertance from the measured impedance such that the non-causality in the reflectance is minimized in the frequency domain using the Hilbert transform. The method is thus capable of estimating plane-wave quantities of the sought-for parameters by supplying only...

  2. Corrosion evaluation of heat recovery steam generator superheater tube in two methods of testing: Tafel polarization and electrochemical impedance spectroscopy (EIS)

    Science.gov (United States)

    Santoso, Rio Pudjidarma; Riastuti, Rini

    2018-05-01

    The purpose of this research is to evaluate the corrosion process which occurs on the water side of Heat Recovery Steam Generator (HRSG) superheater tube. The tube was 13CrMo44 and divided into 3 types of specimen: new tube, used tube (with oxide layer on surface), cleaned-used tube (without oxide layer on surface). The evaluation of corrosion parameters wasperformed using deaerated ultra-high purity water (boiler feed water) in two methods of testing: Tafel polarization and Electrochemical Impedance Spectroscopy (EIS). Tafel polarization was excellent as its capability to show the value of corrosion current and the corrosion rate explicitly, on the other hand, EIS was excellent as its capability to explain for corrosion mechanism on metal interface in detail. Both methods showed that the increase of electrolyte temperature from 25°C to 55°C would increase the corrosion rate with the mechanism of decreasing polarization resistance due to thinning out the passive film thickness and enlarge the area of reduction reaction of cathode. Magnetite oxide scale which is laid on the surface of used tube specimen shows protective nature to reduce the corrosion rate, and clear up this oxide would increase the corrosion rate back as new tube.

  3. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  4. Preoperative management of surgical patients by "shortened fasting time": a study on the amount of total body water by multi-frequency impedance method.

    Science.gov (United States)

    Taniguchi, Hideki; Sasaki, Toshio; Fujita, Hisae

    2012-01-01

    Preoperative fasting is an established procedure to be practiced for patients before surgery, but optimal preoperative fasting time still remains controversial. The aim of this study was to investigate the effect of "shortened preoperative fasting time" on the change in the amount of total body water (TBW) in elective surgical patients. TBW was measured by multi-frequency impedance method. The patients, who were scheduled to undergo surgery for stomach cancer, were divided into two groups of 15 patients each. Before surgery, patients in the control group were managed with conventional preoperative fasting time, while patients in the "enhanced recovery after surgery (ERAS)" group were managed with "shortened preoperative fasting time" and "reduced laxative medication." TBW was measured on the day before surgery and the day of surgery before entering the operating room. Defecation times and anesthesia-related vomiting and aspiration were monitored. TBW values on the day of surgery showed changes in both groups as compared with those on the day before surgery, but the rate of change was smaller in the ERAS group than in the control group (2.4±6.8% [12 patients] vs. -10.6±4.6% [14 patients], pfasting time" and "reduced administration of laxatives" is effective in the maintenance of TBW in elective surgical patients.

  5. Electrical Impedance Tomography Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal for the Electrical Impedance Tomography Technology (EITT) project is to develop a reliable portable, lightweight device providing two-dimensional...

  6. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  7. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  8. Electrical impedance tomography: topology optimization

    International Nuclear Information System (INIS)

    Miranda, Lenine Campos

    2013-01-01

    The Electrical Impedance Tomography (EIT) is a study of body parts who use electric current. Is studied through computers resistance or conductivity of these parts, producing an image used for medical diagnosis. A body is wrapped in a blanket placed with small electrodes and receivers of electric current, potential difference. Based on data obtained from a series of measurements at the electrodes, one by one, sending and receiving, you can perform a numerical phantom, where each 'voxel' of the image formed computationally represents the impedance of biological tissue. In Brazil, studies on electrical impedance tomography (EIT) has not yet started. Such equipment are measured tensions - potential difference - between each electrode / sensor one by one, as a way to Simple Combinatorial Analysis. The sequence and the way it is measured strains are in the final image quality. Finite Element Method Interactive, whose algorithm is based on Dialectical Method. We use an initial function with the objective of maximizing the data quantitatively, for better qualitative analysis. Topology Optimization methods are used to improve the image reconstruction. Currently the study is quite primitive related to the theory that shows how to power the new science studied. The high quality images requires a difficulty in obtaining. This work is not intended for detailed for analysis in any tissue or organ specific, but in general terms. And the formation of the 2D image. 3D need a reconstructor to part. (author)

  9. Electrical Impedance Measurements of PZT Nanofiber Sensors

    Directory of Open Access Journals (Sweden)

    Richard Galos

    2017-01-01

    Full Text Available Electrical impedance measurements of PZT nanofiber sensors were performed using a variety of methods over a frequency spectrum ranging from DC to 1.8 GHz. The nanofibers formed by electrospinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. Special matching circuits with ultrahigh input impedance were fabricated to produce low noise, measurable sensor outputs. Material properties including resistivity and dielectric constant are derived from the impedance measurements. The resulting material properties are also compared with those of individual nanofibers being tested using conductive AFM and Scanning Conductive Microscopy.

  10. RHIC ABORT KICKER WITH REDUCED COUPLING IMPEDANCE

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2002-01-01

    Kicker magnets typically represent the most important contributors to the transverse impedance budget of accelerators and storage rings. Methods of reducing the impedance value of the SNS extraction kicker presently under construction and, in view of a future performance upgrade, that of the RHIC abort kicker have been thoroughly studied at this laboratory. In this paper, the investigation of a potential improvement from using ferrite different from the BNL standard CMD5005 is reported. Permeability measurements of several ferrite types have been performed. Measurements on two kicker magnets using CMD5005 and C2050 suggest that the impedance of a magnet without external resistive damping, such as the RHIC abort kicker, would benefit

  11. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  12. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  13. Microbiology and optimization of hydrogen fermentation and bioelectricity production

    Energy Technology Data Exchange (ETDEWEB)

    Makinen, A.

    2013-11-01

    This work investigated dark fermentative hydrogen (H{sub 2}) and bioelectricity production from carbohydrates. Meso- and thermophilic fermentative and mesophilic exoelectrogenic bacteria were enriched from different natural sources. The H{sub 2} production from different hexoses and pentoses, them main constituents of lignocellulose, was studied in batch assays. H{sub 2} production from xylose was examined in continuous stirred tank reactor (CSTR). Operational parameters for H{sub 2} production were optimized. Bioelectricity production was studied in microbial fuel cells and process parameters were optimized. Dynamics of microbial communities in H{sub 2} and bioelectricity production processes were determined. A novel thermophilic dark fermentative H{sub 2} producing bacterium, Thermovorax subterraneus, was enriched and isolated from geothermal underground mine. T. subterraneus had the optimum growth temperature of 72 deg C and the maximum H{sub 2} yield of 1.4 mol/mol glucose in batch assay. The main soluble fermentative end products of T. subterraneus were acetate and ethanol. Thermophilic dark fermentative mixed culture enriched from hot spring (Hisarlan, Turkey) had the maximum H{sub 2} yield of 1.7 mol/mol glucose. The optimal environmental parameters to maximize H{sub 2} yield were temperature 52 deg C, initial pH 6.5, 40 mg/L Fe{sup 2+}, 4.5 g/L yeast extract and glucose concentration of 4 g/L. Increasing the glucose concentration to 18 g/L increased the maximum H{sub 2} production rate to 56.2 mmol H{sub 2}/h/L. Environmental parameters had a significant effect on metabolic pathways of fermentation. Another hot spring (Hisarkoy, Turkey) enrichment culture was able to ferment different sugars to H{sub 2} favoring pentoses over hexoses. The best H{sub 2} yields in batch assays were obtained from pentoses: xylose, arabinose and ribose yielded 21, 15 and 8 % of the theoretical yield, respectively; whilst on glucose the yield was only 2 % of the theoretical

  14. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    Science.gov (United States)

    Degtiarenko, Pavel V [Williamsburg, VA; Popov, Vladimir E [Newport News, VA

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  15. Superconducting active impedance converter

    International Nuclear Information System (INIS)

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures

  16. Broadband electrical impedance matching for piezoelectric ultrasound transducers.

    Science.gov (United States)

    Huang, Haiying; Paramo, Daniel

    2011-12-01

    This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.

  17. VISUALIZATION OF BIOLOGICAL TISSUE IMPEDANCE PARAMETERS

    Directory of Open Access Journals (Sweden)

    V. I. Bankov

    2016-01-01

    Full Text Available Objective. Investigation the opportunity for measurement of biological tissue impedance to visualize its parameters.Materials and methods. Studies were undertook on the experimental facility, consists of registrating measuring cell, constructed from flat inductors system, formed in oscillatory circuit, herewith investigated biological tissue is the part of this oscillatory circuit. An excitation of oscillatory circuit fulfilled by means of exciter inductor which forms impulse complex modulated electromagnetic field (ICM EMF. The measurement process and visualizations provided by set of certificated instruments: a digital oscillograph AKTAKOM ADS-2221MV, a digital generator АКТАКОМ AWG-4150 (both with software and a gauge RLC E7-22. Comparative dynamic studies of fixed volume and weight pig’s blood, adipose tissue, muscular tissue impedance were conducted by contact versus contactless methods. Contactless method in contrast to contact method gives opportunity to obtain the real morphological visualization of biological tissue irrespective of their nature.Results. Comparison of contact and contactless methods of impedance measurement shows that the inductance to capacitance ratio X(L / X(C was equal: 17 – for muscular tissue, 4 – for blood, 1 – for adipose tissue. It demonstrates the technical correspondence of both impedance registration methods. If propose the base relevance of X (L and X (C parameters for biological tissue impedance so contactless measurement method for sure shows insulating properties of adipose tissue and high conductivity for blood and muscular tissue in fixed volume-weight parameters. Registration of biological tissue impedance complex parameters by contactless method with the help of induced ICM EMF in fixed volume of biological tissue uncovers the most important informative volumes to characterize morphofunctional condition of biological tissue namely X (L / X (C.Conclusion. Contactless method of biological

  18. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    A method for establishing a complex value of the short-circuit impedance from naturally occurring variations in voltage and current is discussed. It is the symmetrical three phase impedance at the fundamental grid frequency there is looked for. The positive sequence components in voltage...... and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  19. Impedance pattern of vaginal and vestibular mucosa in cyclic goats

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was mea­sured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im­pe­dan­ce was measured once a day from 4 days before the expected oestrus to 6 days after onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01 and increased du­ring oestrus (P < 0.01. The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01 and increased after oestrus (P < 0.01. The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig­ni­fi­cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats.

  20. Bioelectricity-AQA, one of the first MOOC courses in engineering.

    Science.gov (United States)

    Barr, Roger C

    2014-01-01

    Bioelectricity-AQA was one of the first massively open online courses in engineering, having been given the first time via Coursera starting in September, 2012. This report provides some detail on its background, presentation, enrollment, and lessons learned.

  1. Mechanical Impedance Modeling of Human Arm: A survey

    Science.gov (United States)

    Puzi, A. Ahmad; Sidek, S. N.; Sado, F.

    2017-03-01

    Human arm mechanical impedance plays a vital role in describing motion ability of the upper limb. One of the impedance parameters is stiffness which is defined as the ratio of an applied force to the measured deformation of the muscle. The arm mechanical impedance modeling is useful in order to develop a better controller for system that interacts with human as such an automated robot-assisted platform for automated rehabilitation training. The aim of the survey is to summarize the existing mechanical impedance models of human upper limb so to justify the need to have an improved version of the arm model in order to facilitate the development of better controller of such systems with ever increase in complexity. In particular, the paper will address the following issue: Human motor control and motor learning, constant and variable impedance models, methods for measuring mechanical impedance and mechanical impedance modeling techniques.

  2. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.; Kundhikanjana, W.; Peng, H.; Cui, Y.; Kelly, M. A.; Shen, Z. X.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately

  3. Laboratory scale tests of electrical impedence tomography

    International Nuclear Information System (INIS)

    Binley, A; Daily, W; LaBredcque, D; Ramirez, A.

    1998-01-01

    Electrical impedance tomographs (magnitude and phase) of known, laboratory-scale targets are reported. Three methods are used to invert electrical impedance data and their tomographs compared. The first method uses an electrical resistance tomography (ERT) algonthm (designed for DC resistivity inversion) to perform impedance magnitude inversion and a linearized perturbation approach (PA) to invert the imaginary part. The second approximate method compares ERT magnitude inversions at two frequencies and uses the frequency effect (FE) to compute phase tomographs. The third approach, electrrcal impedance tomography (EIT), employs fully complex algebra to account for the real and imaginary components of electrical impedance data. The EIT approach provided useful magnitude and phase images for the frequency range of 0.0625 to 64 Hz; images for higher frequencies were not reliable. Comparisons of the ERT and EIT magnitude images show that both methods provided equivalent results for the water blank, copper rod and PVC rod targets. The EIT magnitude images showed better spatial resolutron for a sand-lead mixture target. Phase images located anomalies of both high and low contrast IP and provided better spatial resolution than the magnitude images. When IP was absent from the data, the EIT algorithm reconstructed phase values consistent with the data noise levels

  4. SSC kicker impedances

    International Nuclear Information System (INIS)

    Colton, E.P.; Wang, T.F.

    1985-01-01

    The longitudinal and transverse complex impedances Z/sub l//n and Z/sub t/, respectively, have been calculated for both the SSC injection and abort kickers. The calculations assumed that no attempt was made to shield the beam from the kickers. We took the injection and abort kickers to be as specified. The injection kickers were ferrite with a single-turn design, and the abort kickers were of a ''window-frame design'' with tape wound cores

  5. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...

  6. Impedance analysis of subwoofer systems

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    The electrical impedance of four low-frequency loudspeaker systems is analyzed. The expression for this impedance is obtained directly from the acoustical analogous circuit. Formulas are derived for calculating the small-signal parameters from the frequencies of impedance minima and maxima of two

  7. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J S [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  8. Line impedance estimation using model based identification technique

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Agelidis, Vassilios; Teodorescu, Remus

    2011-01-01

    The estimation of the line impedance can be used by the control of numerous grid-connected systems, such as active filters, islanding detection techniques, non-linear current controllers, detection of the on/off grid operation mode. Therefore, estimating the line impedance can add extra functions...... into the operation of the grid-connected power converters. This paper describes a quasi passive method for estimating the line impedance of the distribution electricity network. The method uses the model based identification technique to obtain the resistive and inductive parts of the line impedance. The quasi...

  9. Results from a Novel Method for Corrosion Studies of Electroplated Lithium Metal Based on Measurements with an Impedance Scanning Electrochemical Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Martin Winter

    2013-07-01

    Full Text Available A new approach to study the chemical stability of electrodeposited lithium on a copper metal substrate via measurements with a fast impedance scanning electrochemical quartz crystal microbalance is presented. The corrosion of electrochemically deposited lithium was compared in two different electrolytes, based on lithium difluoro(oxalato borate (LiDFOB and lithium hexafluorophosphate, both salts being dissolved in solvent blends of ethylene carbonate and diethyl carbonate. For a better understanding of the corrosion mechanisms, scanning electron microscopy images of electrodeposited lithium were also consulted. The results of the EQCM experiments were supported by AC impedance measurements and clearly showed two different corrosion mechanisms caused by the different salts and the formed SEIs. The observed mass decrease of the quartz sensor of the LiDFOB-based electrolyte is not smooth, but rather composed of a series of abrupt mass fluctuations in contrast to that of the lithium hexafluorophosphate-based electrolyte. After each slow decrease of mass a rather fast increase of mass is observed several times. The slow mass decrease can be attributed to a consolidation process of the SEI or to the partial dissolution of the SEI leaving finally lithium metal unprotected so that a fast film formation sets in entailing the observed fast mass increases.

  10. Wavelet analysis of the impedance cardiogram waveforms

    Science.gov (United States)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  11. Wavelet analysis of the impedance cardiogram waveforms

    International Nuclear Information System (INIS)

    Podtaev, S; Stepanov, R; Dumler, A; Chugainov, S; Tziberkin, K

    2012-01-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt) max ) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  12. LIA longitudinal coupling impedance

    International Nuclear Information System (INIS)

    Faltens, A.

    1980-01-01

    The beam generated fields enter into the problems of waveform generation and longitudinal stability. In the former, provision must be made for the longitudinally defocusing forces due to the space charge and the beam loading effects on the accelerating voltage due to the current of a presumably known bunch. In the latter, the concern is for the growth of unintentional perturbations to unacceptably large values through the interaction of the charge and current fluctuations with the rest of the beam and the surrounding structures. These beam generated electric fields may be related to the beam current through a coupling impedance

  13. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  14. Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes; Schallstrahlungskontrast in MR-Phasenbildern. Methode zur Darstellung von Elastizitaets-, Schalldaempfungs- und Schallimpedanzaenderungen

    Energy Technology Data Exchange (ETDEWEB)

    Radicke, Marcus

    2009-12-18

    The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm{sup 2} and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [German] Die in dieser Arbeit praesentierte Methode kombiniert Ultraschalltechniken mit der Magnetresonanztomographie (MRT). Eine Ultraschallwelle ruft in absorbierenden Medien eine statische Kraft in Schallausbreitungsrichtung hervor. Die Kraft fuehrt bei Schallintensitaeten von einigen W/cm{sup 2} und einer Schallfrequenz im niederen MHz-Bereich zu einer Gewebeverschiebung im Mikrometerbereich. Diese Gewebeverschiebung haengt ab von der Schallleistung, der Schallfrequenz, der Schallabsorption und den elastischen Eigenschaften des Gewebes. Es wurde eine MRT-Sequenz der Siemens Healthcare AG modifiziert, so dass sie (indirekt) die Gewebeverschiebung misst, als Grauwerte kodiert und als 2D-Bild darstellt. Anhand der Grauwerte kann der Schallstrahlverlauf in dem Gewebe visualisiert werden, und so koennen zusaetzlich Schallhindernisse (Aenderungen der Schallkennimpedanz) aufgespuert werden. Mit den

  15. Electrical impedance tomography

    Science.gov (United States)

    Lobo, Beatriz; Hermosa, Cecilia; Abella, Ana

    2018-01-01

    Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way. PMID:29430443

  16. Beam measurements of the LHC impedance and validation of the impedance model

    CERN Document Server

    Esteban Müller, J F; Bohl, T; Mounet, N; Shaposhnikova, E; Timko, H

    2014-01-01

    Different measurements of the longitudinal impedance of the LHC done with single bunches with various intensities and longitudinal emittances during measurement sessions in 2011-2012 are compared with particle simulations based on the existing LHC impedance model. The very low reactive impedance of the LHC, with Im Z=n = 0.08, is not easy to measure. The most sensitive observation is the loss of Landau damping, which shows at which energy bunches become unstable depending on their parameters. In addition, the synchrotron frequency shift due to the reactive impedance was estimated following two methods. Firstly, it was obtained from the peak-detected Schottky spectrum. Secondly, a sine modulation in the RF phase was applied to the bunches of different intensities and the modulation frequency was scanned. In both cases, the synchrotron frequency shift was of the order of the measurement precision.

  17. Study on electrical impedance matching for broadband ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon Woo [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Center for Safety Measurement, Daejeon (Korea, Republic of); Baek, Kwang Sae [Elache Co., Busan (Korea, Republic of)

    2017-02-15

    Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of μm) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately 50 Ω to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.

  18. Biogenic metallic nanoparticles as catalyst for bioelectricity production: A novel approach in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Saravanakumar, Kandasamy, E-mail: saravana732@gmail.com [School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai (China); State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai (China); Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai (China); MubarakAli, Davoodbasha [Microbial Genetic Engineering Laboratory, Division of Bioengineering, College of Life Science and Bioengineering, Incheon National University, Songdo 406772, Incheon (Korea, Republic of); Department of Microbiology, School of Lifesciences, Bharathidasan University, Tiruchirappalli 620024 (India); Kathiresan, Kandasamy [Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai 608 502, Tamil Nadu (India); Thajuddin, Nooruddin [Department of Microbiology, School of Lifesciences, Bharathidasan University, Tiruchirappalli 620024 (India); Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Alharbi, Naiyf S. [Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Chen, Jie, E-mail: jiechen59@sjtu.edu.cn [School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai (China); State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai (China); Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai (China)

    2016-01-15

    Highlights: • Trichoderma sp., showed an abilities to synthesis of AgNPs and AuNPs with an excellent stability. • AuNPs significantly enhanced the bioelectricity production by MFC of anaerobic fermentation as catalyst. • Maximum bioelectricity production was optimized and obtained the voltage of 432.80 mA using RSM. - Abstract: The present work aimed to use the biogenic metallic nanoparticles as catalyst for bioelectricity production in microbial fuel cell (MFC) approach under anaerobic condition. Silver and gold nanoparticles (AuNPs) were synthesized using Trichoderma sp. Particle size and cystallinity were measured by X-ray diffraction revealed the crystalline structure with average size of 36.17 nm. Electron microscopic studies showed spherical shaped silver nanoparticles (AgNPs) and cubical shaped AuNPs with size ranges from 50 to 150 nm. The concentration of biogenic metallic nanoparticles as catalyst for enhanced bioelectricity generations and estimated by response surface methodology (RSM) and found at the greatest of 342.80 mA under optimized conditions are time interval, temperature, nanoparticles used as 63 h, 28 ± 2.0 °C, 22.54 mg l{sup −1} (AgNPs) and 25.62 mg l{sup −1} (AuNPs) in a batch reactor. AuNPs acted as an excellent catalyst to enhance the bioelectricity production. This novel technique could be used for eco-friendly, economically feasible and facile electricity production.

  19. Biogenic metallic nanoparticles as catalyst for bioelectricity production: A novel approach in microbial fuel cells

    International Nuclear Information System (INIS)

    Saravanakumar, Kandasamy; MubarakAli, Davoodbasha; Kathiresan, Kandasamy; Thajuddin, Nooruddin; Alharbi, Naiyf S.; Chen, Jie

    2016-01-01

    Highlights: • Trichoderma sp., showed an abilities to synthesis of AgNPs and AuNPs with an excellent stability. • AuNPs significantly enhanced the bioelectricity production by MFC of anaerobic fermentation as catalyst. • Maximum bioelectricity production was optimized and obtained the voltage of 432.80 mA using RSM. - Abstract: The present work aimed to use the biogenic metallic nanoparticles as catalyst for bioelectricity production in microbial fuel cell (MFC) approach under anaerobic condition. Silver and gold nanoparticles (AuNPs) were synthesized using Trichoderma sp. Particle size and cystallinity were measured by X-ray diffraction revealed the crystalline structure with average size of 36.17 nm. Electron microscopic studies showed spherical shaped silver nanoparticles (AgNPs) and cubical shaped AuNPs with size ranges from 50 to 150 nm. The concentration of biogenic metallic nanoparticles as catalyst for enhanced bioelectricity generations and estimated by response surface methodology (RSM) and found at the greatest of 342.80 mA under optimized conditions are time interval, temperature, nanoparticles used as 63 h, 28 ± 2.0 °C, 22.54 mg l"−"1 (AgNPs) and 25.62 mg l"−"1 (AuNPs) in a batch reactor. AuNPs acted as an excellent catalyst to enhance the bioelectricity production. This novel technique could be used for eco-friendly, economically feasible and facile electricity production.

  20. Broadband impedance of the NESTOR storage ring

    International Nuclear Information System (INIS)

    Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

    2011-01-01

    The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

  1. Evaluation of ring impedance of the Photon Factory storage ring

    International Nuclear Information System (INIS)

    Kiuchi, T.; Izawa, M.; Tokumoto, S.; Hori, Y.; Sakanaka, S.; Kobayashi, M.; Kobayakawa, H.

    1992-05-01

    The loss parameters of the ducts in the Photon Factory (PF) storage ring were evaluated using the wire method and the code TBCI. Both the measurement and the calculation were done for a different bunch length (σ) ranging from 23 to 80 ps. The PF ring impedance was estimated to be |Z/n|=3.2 Ω using the broadband impedance model. The major contribution to the impedance comes from the bellows and the gate valve sections. Improvements of these components will lower the ring impedance by half. (author)

  2. Detection of irradiated potatoes by impedance measurement

    International Nuclear Information System (INIS)

    Hayashi, T.; Todoriki, S.; Otobe, K.; Sugiyama, J.

    1996-01-01

    Potato is one of the major food items to be treated with ionising radiation and potatoes are irradiated on a large scale in several countries. Every year around 15,000 t of potatoes are irradiated at doses of 60 to 150 Gy (average dose is about 100 Gy) in Japan. Although various methods to detect irradiated potatoes have been investigated, no established method has been reported. Measuring electrical conductivity or impedance of potatoes has been reported as a promising method for the detection of irradiated potatoes. In previous studies it has been found that the ratio of impedance magnitude at 50 kHz to that at 5 kHz, measured immediately after puncturing a potato tuber, is dependent upon the dose applied to the tuber, independent of storage temperature and stable during storage after irradiation. The aim of this study was to establish the optimum conditions for impedance measurement and to examine the applicability of the impedance measuring method to various cultivars (cv.) of potatoes. (author)

  3. [Spatial organization of bioelectrical brain activity in epilepsy and amenorrhea of central genesis].

    Science.gov (United States)

    Avakian, G N; Oleĭnikova, O M; Nerobkova, L N; Dovletkhanova, E R; Mitrofanov, A A; Gusev, E I

    2002-01-01

    The study aimed at modification of co-herent analysis (CA), as a mathematical method for EEG data processing for objective evaluation of bioelectric brain activity spatial organization in women with epilepsy and secondary amenorrhea of central genesis. One hundred sixty one women (30 with epilepsy, 116 with amenorrhea and 115 controls aged 15 to 41 years) have been examined. Characteristic changes of cortico-cortical inter- and intra-hemisphere relations for patients with catamenial (CTM) and noncatamenial (NCTM) epilepsy in different menstrual cycle terms were found. The most distinct changes were detected in theta-activity analysis. In the beginning of menstrual cycle, the patients with CTM epilepsy exhibited higher CA indices in theta-rhythm range in all right hemisphere pairs studied. On the contrary, patients with NCTM epilepsy exhibited lower CA indices mainly in the right brain hemisphere. alpha-rhythm spatial organization analysis in the same patients showed similar correlations, but they were better expressed in alpha-rhythm generation zone: in the beginning of menstrual cycle CA indices were high in patients with CTM epilepsy and low in those with NCTM epilepsy. Comparing to controls, patients with secondary amenorrhea of central genesis showed most distinct changes in theta-activity towards the CA indices increase in the majority of the leads. In patients with epilepsy and amenorrhea, CA indices of right brain hemisphere and intra-central temporal lead pairs were lower than in patients with amenorrhea without epilepsy by both alpha- and theta-rhythms.

  4. NOTE: Impedance magnetocardiogram

    Science.gov (United States)

    Kandori, Akihiko; Miyashita, Tsuyoshi; Suzuki, Daisuke; Yokosawa, Koichi; Tsukada, Keiji

    2001-02-01

    We have developed an impedance magnetocardiogram (IMCG) system to detect the change of magnetic field corresponding to changes in blood volume in the heart. A low magnetic field from the electrical activity of the human heart - the so-called magnetocardiogram (MCG) - can be simultaneously detected by using this system. Because the mechanical and electrical functions in the heart can be monitored by non-invasive and non-contact measurements, it is easy to observe the cardiovascular functions from an accurate sensor position. This system uses a technique to demodulate induced current in a subject. A flux-locked circuit of a superconducting quantum interference device has a wide frequency range (above 1 MHz) because a constant current (40 kHz) is fed through the subject. It is shown for the first time that the system could measure IMCG signals at the same time as MCG signals.

  5. On Impedance Spectroscopy of Supercapacitors

    Science.gov (United States)

    Uchaikin, V. V.; Sibatov, R. T.; Ambrozevich, A. S.

    2016-10-01

    Supercapacitors are often characterized by responses measured by methods of impedance spectroscopy. In the frequency domain these responses have the form of power-law functions or their linear combinations. The inverse Fourier transform leads to relaxation equations with integro-differential operators of fractional order under assumption that the frequency response is independent of the working voltage. To compare long-term relaxation kinetics predicted by these equations with the observed one, charging-discharging of supercapacitors (with nominal capacitances of 0.22, 0.47, and 1.0 F) have been studied by means of registration of the current response to a step voltage signal. It is established that the reaction of devices under study to variations of the charging regime disagrees with the model of a homogeneous linear response. It is demonstrated that relaxation is well described by a fractional stretched exponent.

  6. What is the bioelectric that the sugar industry and Cuba need?

    International Nuclear Information System (INIS)

    Lodos, Jorge

    2015-01-01

    The most relevant bioelectric illustrating its current development on the basis of which technical and economic parameters to support the definition of a strategy are discussed are described. These include, efficiency, consumption of process steam, alternative biomass and storage, water quality, the ability to harvest and no harvest, new technologies, cost and price of biomass and kWh , investment and financing conditions, among others. We conclude that the result of bioelectrical has to be not only ecological but also economic, to be maximized power production operating at higher pressure and temperatures possible with turbo extraction-condensing and biomass availability is crucial because regulating capacity, economies of scale, duration of the operation and profitability of bioelectrical. We must urgently assess whole cane processing and eventually to the briquetting of biomass store. It is desirable to standardize the capacity of sugar factories. The SEN can and must assimilate biokWh at any time of day, anywhere from Cuba to occur. (full text)

  7. Impedance deduction for vegetated roof surfaces : multiple geometry strategy

    NARCIS (Netherlands)

    Liu, C.; Hornikx, M.

    2016-01-01

    The transfer function method is an efficient procedure to deduce the ground surface impedance from short-range propagation measurements using one point source. It is able to provide a reasonable prediction of the surface impedance of a vegetated roof as well, and the characteristics of the vegetated

  8. Resuscitation Outcomes Consortium (ROC) PRIMED cardiac arrest trial methods part 1: rationale and methodology for the impedance threshold device (ITD) protocol.

    Science.gov (United States)

    Aufderheide, Tom P; Kudenchuk, Peter J; Hedges, Jerris R; Nichol, Graham; Kerber, Richard E; Dorian, Paul; Davis, Daniel P; Idris, Ahamed H; Callaway, Clifton W; Emerson, Scott; Stiell, Ian G; Terndrup, Thomas E

    2008-08-01

    The primary aim of this study is to compare survival to hospital discharge with a modified Rankin score (MRS)CPR) plus an active impedance threshold device (ITD) versus standard CPR plus a sham ITD in patients with out-of-hospital cardiac arrest. Secondary aims are to compare functional status and depression at discharge and at 3 and 6 months post-discharge in survivors. Prospective, double-blind, randomized, controlled, clinical trial. Patients with non-traumatic out-of-hospital cardiac arrest treated by emergency medical services (EMS) providers. EMS systems participating in the Resuscitation Outcomes Consortium. Based on a one-sided significance level of 0.025, power=0.90, a survival with MRSCPR and sham ITD, and two interim analyses, a maximum of 14,742 evaluable patients are needed to detect a 6.69% survival with MRSCPR and active ITD (1.36% absolute survival difference). If the ITD demonstrates the hypothesized improvement in survival, it is estimated that 2700 deaths from cardiac arrest per year would be averted in North America alone.

  9. Development on electromagnetic impedance function modeling and its estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sutarno, D., E-mail: Sutarno@fi.itb.ac.id [Earth Physics and Complex System Division Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung (Indonesia)

    2015-09-30

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  10. Intraesophageal impedance monitoring: clinical studies

    NARCIS (Netherlands)

    Conchillo Armendáriz, J.M.

    2007-01-01

    Electrical impedance (Z) between two electrodes is the ratio between applied voltage (U) and resulting current (I). In electrical impedance monitoring the resistance to electrical flow in an alternating current circuit is measured. Multichannel esophageal monitoring can be measured by using an

  11. Determination of beam coupling impedance in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Niedermayer, Uwe

    2016-07-01

    The concept of beam coupling impedance describes the electromagnetic interaction of uniformly moving charged particles with their surrounding structures in the Frequency Domain (FD). In synchrotron accelerators, beam coupling impedances can lead to beam induced component heating and coherent beam instabilities. Thus, in order to ensure the stable operation of a synchrotron, its impedances have to be quantified and their effects have to be controlled. Nowadays, beam coupling impedances are mostly obtained by Fourier transform of wake potentials, which are the results of Time Domain (TD) simulations. However, at low frequencies, low beam velocity, or for dispersive materials, TD simulations become unhandy. In this area, analytical calculations of beam coupling impedance in the FD, combined with geometry approximations, are still widely used. This thesis describes the development of two electromagnetic field solvers to obtain the beam coupling impedance directly in the FD, where the beam velocity is only a parameter and dispersive materials can be included easily. One solver is based on the Finite Integration Technique (FIT) on a staircase mesh. It is implemented both in 2D and 3D. However, the staircase mesh is inefficient on curved structures, which is particularly problematic for the modeling of a dipole source, that is required for the computation of the transverse beam coupling impedance. This issue is overcome by the second solver developed in this thesis, which is based on the Finite Element Method (FEM) on an unstructured triangular mesh. It is implemented in 2D and includes an optional Surface Impedance Boundary Condition (SIBC). Thus, it is well suited for the computation of longitudinal and transverse impedances of long beam pipe structures of arbitrary cross-section. Besides arbitrary frequency and beam velocity, also dispersive materials can be chosen, which is crucial for the computation of the impedance of ferrite kicker magnets. Numerical impedance

  12. Integrative assessment of kick boxers’ brain blood circulation and bio-electrical activity in conditions of correction technologies’ application

    Directory of Open Access Journals (Sweden)

    Y.N. Romanov

    2016-06-01

    Full Text Available Purpose: to scientifically substantiate the role of para-vertebral impacts on blood circulation and bio-electrical activity of kick boxers’ cortex. Material: in the research participated kick boxers (main group, n=62 and university students (control group, n=25 of 18-23 years’ age. Assessment of para-vertebral impacts with device Armos and classic massage was fulfilled with the help of the following methodic: trans-cranial dopplerography of head main arteries and cortex EEG of the tested. Results: it was found that with the help of para-vertebral impacts by device Armos linear velocity of cerebral blood flow reduces to normal limits and in- and inter-hemispheres’ interaction strength increases. Conclusions: para-vertebral impacts by device Armos activate integrative processes and inter-hemispheres’ interactions of different cortex areas of kick boxers. It can witness about better formation of functional systems, ensuring sports efficiency.

  13. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding...

  14. Improved Decoupling for 13C coil Arrays Using Non-Conventional Matching and Preamplifier Impedance

    DEFF Research Database (Denmark)

    Sanchez, Juan Diego; Johansen, Daniel Højrup; Hansen, Rie Beck

    In this study, we describe a method to obtain improved preamplifier decoupling for receive-only coils. The method relies on the better decoupling obtained when coils are matched to an impedance higher than 50 . Preamplifiers with inductive imaginary impedance and low real impedance, increase...

  15. Development of three-dimension microelectrode array for bioelectric measurement using the liquidmetal-micromolding technique

    International Nuclear Information System (INIS)

    Liu, Ran; Yang, Xueyao; Chen, Weixing; Jin, Cuiyun; Fu, Jingjing; Liu, Jing

    2013-01-01

    A method of manufacturing three-dimension microneedle electrode arrays is presented in this paper using the micromolding technology with liquid metal at room temperature, based on the physical property of the Bi-In-Sn liquid metal alloy, being its melting point especially low. Observed under scanning electron microscopy, the needle body of the electrode chip manufactured using this method has a good consistency. Skin penetration test in-vitro indicates that the microneedle electrode can pierce the stratum corneum and cross the high-impedance layer to acquire electrical signals. Electrical impedance and polarization voltage experimental results show that the electrode chips have great electric characteristics and meet the practical application demands

  16. Development of three-dimension microelectrode array for bioelectric measurement using the liquidmetal-micromolding technique

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ran, E-mail: liuran@tsinghua.edu.cn; Yang, Xueyao; Chen, Weixing [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); Jin, Cuiyun; Fu, Jingjing [College of Information Science and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Liu, Jing [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2013-11-04

    A method of manufacturing three-dimension microneedle electrode arrays is presented in this paper using the micromolding technology with liquid metal at room temperature, based on the physical property of the Bi-In-Sn liquid metal alloy, being its melting point especially low. Observed under scanning electron microscopy, the needle body of the electrode chip manufactured using this method has a good consistency. Skin penetration test in-vitro indicates that the microneedle electrode can pierce the stratum corneum and cross the high-impedance layer to acquire electrical signals. Electrical impedance and polarization voltage experimental results show that the electrode chips have great electric characteristics and meet the practical application demands.

  17. Modern Trends in Imaging XI: Impedance Measurements in the Biomedical Sciences

    Directory of Open Access Journals (Sweden)

    Frederick D. Coffman

    2012-01-01

    Full Text Available Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  18. Characterizing aging effects of lithium ion batteries by impedance spectroscopy

    International Nuclear Information System (INIS)

    Troeltzsch, Uwe; Kanoun, Olfa; Traenkler, Hans-Rolf

    2006-01-01

    Impedance spectroscopy is one of the most promising methods for characterizing aging effects of portable secondary batteries online because it provides information about different aging mechanisms. However, application of impedance spectroscopy 'in the field' has some higher requirements than for laboratory experiments. It requires a fast impedance measurement process, an accurate model applicable with several batteries and a robust method for model parameter estimation. In this paper, we present a method measuring impedance at different frequencies simultaneously. We propose to use a composite electrode model, capable to describe porous composite electrode materials. A hybrid method for parameter estimation based on a combination of evolution strategy and Levenberg-Marquardt method allowed a robust and fast parameter calculation. Based on this approach, an experimental investigation of aging effects of a lithium ion battery was carried out. After 230 discharge/charge cycles, the battery showed a 14% decreased capacity. Modeling results show that series resistance, charge transfer resistance and Warburg coefficient changed thereby their values by approximately 60%. A single frequency impedance measurement, usually carried out at 1 kHz, delivers only information about series resistance. Impedance spectroscopy allows additionally the estimation of charge transfer resistance and Warburg coefficient. This fact and the high sensitivity of model parameters to capacity change prove that impedance spectroscopy together with an accurate modeling deliver information that significantly improve characterization of aging effects

  19. Characterizing aging effects of lithium ion batteries by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Troeltzsch, Uwe [University of the Bundeswehr Munich Institute for Measurement and Automation, 85579 Neubiberg (Germany)]. E-mail: uwe.troeltzsch@unibw-muenchen.de; Kanoun, Olfa [University of the Bundeswehr Munich Institute for Measurement and Automation, 85579 Neubiberg (Germany); Traenkler, Hans-Rolf [University of the Bundeswehr Munich Institute for Measurement and Automation, 85579 Neubiberg (Germany)

    2006-01-20

    Impedance spectroscopy is one of the most promising methods for characterizing aging effects of portable secondary batteries online because it provides information about different aging mechanisms. However, application of impedance spectroscopy 'in the field' has some higher requirements than for laboratory experiments. It requires a fast impedance measurement process, an accurate model applicable with several batteries and a robust method for model parameter estimation. In this paper, we present a method measuring impedance at different frequencies simultaneously. We propose to use a composite electrode model, capable to describe porous composite electrode materials. A hybrid method for parameter estimation based on a combination of evolution strategy and Levenberg-Marquardt method allowed a robust and fast parameter calculation. Based on this approach, an experimental investigation of aging effects of a lithium ion battery was carried out. After 230 discharge/charge cycles, the battery showed a 14% decreased capacity. Modeling results show that series resistance, charge transfer resistance and Warburg coefficient changed thereby their values by approximately 60%. A single frequency impedance measurement, usually carried out at 1 kHz, delivers only information about series resistance. Impedance spectroscopy allows additionally the estimation of charge transfer resistance and Warburg coefficient. This fact and the high sensitivity of model parameters to capacity change prove that impedance spectroscopy together with an accurate modeling deliver information that significantly improve characterization of aging effects.

  20. The Evaluation of Bioelectrical Activity of Pelvic Floor Muscles Depending on Probe Location: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Tomasz Halski

    2013-01-01

    Full Text Available Objectives. The main objective was to determine how the depth of probe placement affects functional and resting bioelectrical activity of the PFM and whether the recorded signal might be dependent on the direction in which the probe is rotated. Participants. The study comprised of healthy, nulliparous women between the ages of 21 and 25. Outcome Measures. Bioelectric activity of the PFM was recorded from four locations of the vagina by surface EMG and vaginal probe. Results. There were no statistically significant differences between the results during functional sEMG activity. During resting sEMG activity, the highest bioelectrical activity of the PFM was observed in the L1 and the lowest in the L4 and a statistically significant difference between the highest and the lowest results of resting sEMG activity was observed (P=0.0043. Conclusion. Different electrodes placement during functional contraction of PFM does not affect the obtained results in sEMG evaluation. In order to diagnose the highest resting activity of PFM the recording plates should be placed toward the anterior vaginal wall and distally from the introitus. However, all of the PFM have similar bioelectrical activity and it seems that these muscles could be treated as a single muscle.

  1. Regulation of cell behavior and tissue patterning by bioelectrical signals: challenges and opportunities for biomedical engineering.

    Science.gov (United States)

    Levin, Michael; Stevenson, Claire G

    2012-01-01

    Achieving control over cell behavior and pattern formation requires molecular-level understanding of regulatory mechanisms. Alongside transcriptional networks and biochemical gradients, there functions an important system of cellular communication and control: transmembrane voltage gradients (V(mem)). Bioelectrical signals encoded in spatiotemporal changes of V(mem) control cell proliferation, migration, and differentiation. Moreover, endogenous bioelectrical gradients serve as instructive cues mediating anatomical polarity and other organ-level aspects of morphogenesis. In the past decade, significant advances in molecular physiology have enabled the development of new genetic and biophysical tools for the investigation and functional manipulation of bioelectric cues. Recent data implicate V(mem) as a crucial epigenetic regulator of patterning events in embryogenesis, regeneration, and cancer. We review new conceptual and methodological developments in this fascinating field. Bioelectricity offers a novel way of quantitatively understanding regulation of growth and form in vivo, and it reveals tractable, powerful control points that will enable truly transformative applications in bioengineering, regenerative medicine, and synthetic biology.

  2. Biliary obstruction dissipates bioelectric sinusoidal-canalicular barrier without altering taurocholate uptake

    International Nuclear Information System (INIS)

    Cotting, J.; Zysset, T.; Reichen, J.

    1989-01-01

    To study immediate events during extrahepatic cholestasis, we investigated the effect of short-term biliary obstruction on the bioelectrical sinusoidal-canalicular barrier in the rat using molecular weight-matched uncharged and negatively charged inert solute pairs. The bioelectrical barrier averaged -22 +/- 5 and -18 +/- 4 mV (NS) using the pair carboxy-/methoxyinulin and ferrocyanide/sucrose, respectively. After a 20-min biliary obstruction both decreased by 61 and 11%, respectively, but only the large molecular weight pair (the inulins) returned to base line after release of the obstruction. Inert solute clearances were increased after short biliary obstruction depending on molecular size and negative charge (ferrocyanide greater than sucrose greater than carboxyinulin greater than inulin), suggesting that both permeability and bioelectrical barriers were affected by obstruction. The hepatic extraction in vivo of a passively transported drug not excreted into bile (D-propranolol) was not affected by obstruction, whereas that of an actively transported drug (glycocholate) decreased from 66 +/- 8 to 41 +/- 20% during biliary obstruction (P less than 0.01). Unidirectional transfer of glycocholate was not affected by short-term biliary obstruction in the situ perfused rat liver; however, 2 min after [14C]glycocholate administration, increased return was observed in hepatic venous effluent in obstructed animals. Our findings demonstrate a loss of the bioelectrical barrier immediately after short-term biliary obstruction. Decreased hepatic extraction in the view of unaltered sinusoidal uptake demonstrates regurgitation of bile into blood during short-term biliary obstruction

  3. The bioelectric code: An ancient computational medium for dynamic control of growth and form.

    Science.gov (United States)

    Levin, Michael; Martyniuk, Christopher J

    2018-02-01

    What determines large-scale anatomy? DNA does not directly specify geometrical arrangements of tissues and organs, and a process of encoding and decoding for morphogenesis is required. Moreover, many species can regenerate and remodel their structure despite drastic injury. The ability to obtain the correct target morphology from a diversity of initial conditions reveals that the morphogenetic code implements a rich system of pattern-homeostatic processes. Here, we describe an important mechanism by which cellular networks implement pattern regulation and plasticity: bioelectricity. All cells, not only nerves and muscles, produce and sense electrical signals; in vivo, these processes form bioelectric circuits that harness individual cell behaviors toward specific anatomical endpoints. We review emerging progress in reading and re-writing anatomical information encoded in bioelectrical states, and discuss the approaches to this problem from the perspectives of information theory, dynamical systems, and computational neuroscience. Cracking the bioelectric code will enable much-improved control over biological patterning, advancing basic evolutionary developmental biology as well as enabling numerous applications in regenerative medicine and synthetic bioengineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Chronic blockade of bioelectric activity in neonatal rat cortex grown in vitro: morphological effects

    NARCIS (Netherlands)

    Ruijter, J. M.; Baker, R. E.; de Jong, B. M.; Romijn, H. J.

    1991-01-01

    Culture thickness, numerical density of neurons and neuronal survival were studied in timed series of control and tetrodotoxin-silenced neocortical cultures to provide information on the role of bioelectric activity on neuronal development. In control cultures, culture thickness and number of

  5. [Prognostic value of chosen parameters of mechanical and bioelectrical uterine activity in prediction of threatening preterm labour].

    Science.gov (United States)

    Zietek, Jerzy; Sikora, Jerzy; Horoba, Krzysztof; Matonia, Adam; Jezewski, Janusz; Magnucki, Jacek; Kobielska, Lucyna

    2009-03-01

    To record and analyse bioelectrical activity of the uterine muscle in the course of physiological pregnancy, labour and threatening premature labour; to define which parameters from the analysis of both electrohysterogram and mechanical activity signal allow us to predict threatening premature labour. Material comprised 62 pregnant women: Group I--27 patients in their first physiological pregnancy, Group II--21 patients in their first pregnancy with symptoms of threatening premature labour, and Group III--14 patients in the first labour period. The on-line analysis of the mechanical (TOCO) and electrical (EHG) contraction activity relied on determination of quantitative parameters of detected uterine contractions. The obtained statistical results demonstrated a possibility to differentiate between Group I and II through the amplitude and contraction area for EHG signal, and only the contraction amplitude for TOCO signal. Additionally, significant differentiating parameters for electrohysterogram are: contraction power and its median frequency. Analyzing Group I and III, significant differences were noted for contraction amplitude and area obtained both from EHG and TOCO signals. Similarly, the contraction power (from EHG) enables us to assign the contractions either to records from Group I or to labour type. There was no significant difference noted between Group II and III. Identification of pregnant women at risk of premature labour should lead to their inclusion in rigorous perinatal surveillance. This requires novel, more sensitive methods that are able to detect early symptoms of the uterine contraction activity increase. Electrohysterography provides complete information on principles of bioelectrical uterine activity. Quantitative parameters of EHG analysis enable the detection of records (contractions) with the symptoms of premature uterine contraction activity.

  6. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...

  7. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary...... from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible...... to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors....

  8. Identification of Critical Transmission Limits in Injection Impedance Plane

    DEFF Research Database (Denmark)

    Jóhannsson, Hjörtur; Østergaard, Jacob; Nielsen, Arne Hejde

    2012-01-01

    In this paper, equations are derived that describe the mapping of critical boundaries and characteristic lines from the three dimensionalPQV-surface into the two-dimensional injection impedance plane (load impedance plane for both positive and negativeresistance). The expressions derived....... The situational awareness method will bedescribed in a later paper, where this paper focuses on the derivations of some system characteristics in the injection (or load)impedance plane. The critical lines from the PQV-surface that are mapped into the impedance plane are the ones representing theconditions where...... the partial derivatives of the variables P,Q and V in respect to each other become zero. In addition to the mappingof the critical lines, some characteristic lines are mapped as well. These include the mapping of the lines of constant P,Q,Vand d from the PQV-surface into the impedance plane. All of the mapped...

  9. Nutritional assessment methods for zinc supplementation in prepubertal non-zinc-deficient children

    Directory of Open Access Journals (Sweden)

    Márcia Marília Gomes Dantas Lopes

    2015-10-01

    Full Text Available Background: Zinc is an essential nutrient that is required for numerous metabolic functions, and zinc deficiency results in growth retardation, cell-mediated immune dysfunction, and cognitive impairment. Objective: This study evaluated nutritional assessment methods for zinc supplementation in prepubertal non-zinc-deficient children. Design: We performed a randomised, controlled, triple-blind study. The children were divided into a control group (10% sorbitol, n=31 and an experimental group (10 mg Zn/day, n=31 for 3 months. Anthropometric and dietary assessments as well as bioelectrical measurements were performed in all children. Results: Our study showed (1 an increased body mass index for age and an increased phase angle in the experimental group; (2 a positive correlation between nutritional assessment parameters in both groups; (3 increased soft tissue, and mainly fat-free mass, in the body composition of the experimental group, as determined using bioelectrical impedance vector analysis; (4 increased consumption of all nutrients, including zinc, in the experimental group; and (5 an increased serum zinc concentration in both groups (p<0.0001. Conclusions: Given that a reference for body composition analysis does not exist for intervention studies, longitudinal studies are needed to investigate vector migration during zinc supplementation. These results reinforce the importance of employing multiple techniques to assess the nutritional status of populations.

  10. Development of impedance matching technologies for ICRF antenna arrays

    International Nuclear Information System (INIS)

    Pinsker, R.I.

    1998-01-01

    All high-power ion cyclotron range of frequency (ICRF) heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time dependent on timescales as rapid as 10 -1 s, while the radio frequency (RF) generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the RF source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In 'lossy passive schemes', reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array. (author)

  11. Development of impedance matching technologies for ICRF antenna arrays

    International Nuclear Information System (INIS)

    Pinsker, R.I.

    1998-03-01

    All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array

  12. Measurement scheme of kicker impedances via beam-induced voltages of coaxial cables

    Energy Technology Data Exchange (ETDEWEB)

    Shobuda, Yoshihiro, E-mail: yoshihiro.shobuda@j-parc.jp [J-PARC Center, JAEA and KEK, 2-4 Shirakata Shirane, Tokaimura, Nakagun, Ibaraki 319-1195 (Japan); Irie, Yoshiro [KEK, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Toyama, Takeshi; Kamiya, Junichiro [J-PARC Center, JAEA and KEK, 2-4 Shirakata Shirane, Tokaimura, Nakagun, Ibaraki 319-1195 (Japan); Watanabe, Masao [Ministry of Education, Culture, Sports, Science and Technology, 3-2-2 Kasumigaseki, Chiyoda, Tokyo 100-8959 (Japan)

    2013-06-11

    A new theory, which satisfies the causality condition, is developed to describe impedances of kicker magnets with coaxial cables. The theoretical results well describe measurement results, which are obtained by standard wire methods. On the other hand, when beams pass through the kicker, voltages are induced at the terminals of coaxial cables. In other words, by analyzing the voltages, the kicker impedance for the beams can be obtained. The observed impedances are consistent with the theoretical results. The theory describes the impedance for non-relativistic beams, as well. The theoretical, simulation and measurement results indicate that the horizontal kicker impedance is drastically reduced by the non-relativistic effect. -- Highlights: ► We develop an innovative method to measure kicker impedance including power cable. ► By analyzing voltages at the ends of coaxial cables, the impedance is derived. ► The horizontal impedance is reduced as the beam becomes non-relativistic.

  13. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  14. Detection of irradiated potatoes by impedance measurements

    International Nuclear Information System (INIS)

    Hayashi, Toru; Sugiyama, Junnichi; Otobe, Kazuki; Todoriki, Setsuko

    1993-01-01

    The impedance ratio at 5kHz to 50kHz (Z 6K /Z 50K ) determined at 22degC at an apical region of potato tuber which was pre-incubated at 22degC for 3 days or longer resulted in the best detection of radian treatment. Irradiated potatoes of 10 cultivars could be detected with this method, and potatoes 'Danshaku' commercially irradiated at Shihoro could be distinguished from unirradiated 'Danshaku'. (author)

  15. Techniques for beam impedance measurements above cutoff

    International Nuclear Information System (INIS)

    Lambertson, G.R.; Jacob, A.F.; Rimmer, R.A.; Voelker, F.

    1990-08-01

    Methods for measuring beam impedance above cutoff have been very limited. For design work on the ALS we have developed two techniques that yield data in the frequency domain with high sensitivity. The first is an extension of the wire method; the second utilizes traveling TM waves to simulate the beam's fields at the wall, and thus avoids the mechanical difficulties of mounting the wire. It is also more sensitive than the other method but the interpretation is complicated by the presence of higher order modes. With either method we were able to detect resonant peaks smaller than 1 Ohm at 10 GHz

  16. Quantitative evaluation of impedance perception characteristics of humans in the man-machine interface

    International Nuclear Information System (INIS)

    Onish, Keiichi; Kim, Young Woo; Obinata, Goro; Hase, Kazunori

    2013-01-01

    We investigated impedance perception characteristics of humans in the man-machine interface. Sensibility or operational feel about physical properties of machine dynamics is obtained through perception process. We evaluated the impedance perception characteristics of humans who are operating a mechanical system, based on extended Scheffe's subjective evaluation method in full consideration of the influence of impedance level, impedance difference, experiment order, individual difference and so on. Constant method based quantitative evaluation was adopted to investigate the influence of motion frequency and change of the impedance on human impedance perception characteristics. Experimental results indicate that humans perceive impedance of mechanical systems based on comparison process of the dynamical characteristics of the systems. The proposed method can be applied to quantify the design requirement of man-machine interface. The effectiveness of the proposed method is verified through experimental results.

  17. Quantitative evaluation of impedance perception characteristics of humans in the man-machine interface

    Energy Technology Data Exchange (ETDEWEB)

    Onish, Keiichi [Yamaha Motor Co., Shizuoka (Japan); Kim, Young Woo [Daegu Techno Park R and D Center, Seoul (Korea, Republic of); Obinata, Goro [Nagoya University, Nagoya (Japan); Hase, Kazunori [Tokyo Metropolitan University, Tokyo (Japan)

    2013-05-15

    We investigated impedance perception characteristics of humans in the man-machine interface. Sensibility or operational feel about physical properties of machine dynamics is obtained through perception process. We evaluated the impedance perception characteristics of humans who are operating a mechanical system, based on extended Scheffe's subjective evaluation method in full consideration of the influence of impedance level, impedance difference, experiment order, individual difference and so on. Constant method based quantitative evaluation was adopted to investigate the influence of motion frequency and change of the impedance on human impedance perception characteristics. Experimental results indicate that humans perceive impedance of mechanical systems based on comparison process of the dynamical characteristics of the systems. The proposed method can be applied to quantify the design requirement of man-machine interface. The effectiveness of the proposed method is verified through experimental results.

  18. Comparison of muscle/lean mass measurement methods: correlation with functional and biochemical testing.

    Science.gov (United States)

    Buehring, B; Siglinsky, E; Krueger, D; Evans, W; Hellerstein, M; Yamada, Y; Binkley, N

    2018-03-01

    DXA-measured lean mass is often used to assess muscle mass but has limitations. Thus, we compared DXA lean mass with two novel methods-bioelectric impedance spectroscopy and creatine (methyl-d3) dilution. The examined methodologies did not measure lean mass similarly and the correlation with muscle biomarkers/function varied. Muscle function tests predict adverse health outcomes better than lean mass measurement. This may reflect limitations of current mass measurement methods. Newer approaches, e.g., bioelectric impedance spectroscopy (BIS) and creatine (methyl-d3) dilution (D3-C), may more accurately assess muscle mass. We hypothesized that BIS and D3-C measured muscle mass would better correlate with function and bone/muscle biomarkers than DXA measured lean mass. Evaluations of muscle/lean mass, function, and serum biomarkers were obtained in older community-dwelling adults. Mass was assessed by DXA, BIS, and orally administered D3-C. Grip strength, timed up and go, and jump power were examined. Potential muscle/bone serum biomarkers were measured. Mass measurements were compared with functional and serum data using regression analyses; differences between techniques were determined by paired t tests. Mean (SD) age of the 112 (89F/23M) participants was 80.6 (6.0) years. The lean/muscle mass assessments were correlated (.57-.88) but differed (p Lean mass measures were unrelated to the serum biomarkers measured. These three methodologies do not similarly measure muscle/lean mass and should not be viewed as being equivalent. Functional tests assessing maximal muscle strength/power (grip strength and jump power) correlated with all mass measures whereas gait speed was not. None of the selected serum measures correlated with mass. Efforts to optimize muscle mass assessment and identify their relationships with health outcomes are needed.

  19. On the longitudinal coupling impedance of a toroidal beam tube

    International Nuclear Information System (INIS)

    Hahn, H.; Tepikian, S.

    1990-01-01

    In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab

  20. MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2001-01-01

    Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S 21 forward transmission coefficient. A commercial 450 Ω twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable in magnitude, but differ from Handbook predictions

  1. Impedance-Source Networks for Electric Power Conversion Part II

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Peng, Fang Zheng; Blaabjerg, Frede

    2015-01-01

    Impedance-source networks cover the entire spectrum of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac) controlled and modulated by different modulation strategies to generate the desired dc or ac voltage and current at the output. A comprehensive review of various impedance......-source-network-based power converters has been covered in a previous paper and main topologies were discussed from an application point of view. Now Part II provides a comprehensive review of the most popular control and modulation strategies for impedance-source network-based power converters/inverters. These methods...

  2. Different radiation impedance models for finite porous materials

    DEFF Research Database (Denmark)

    Nolan, Melanie; Jeong, Cheol-Ho; Brunskog, Jonas

    2015-01-01

    The Sabine absorption coefficients of finite absorbers are measured in a reverberation chamber according to the international standard ISO 354. They vary with the specimen size essentially due to diffraction at the specimen edges, which can be seen as the radiation impedance differing from...... the infinite case. Thus, in order to predict the Sabine absorption coefficients of finite porous samples, one can incorporate models of the radiation impedance. In this study, different radiation impedance models are compared with two experimental examples. Thomasson’s model is compared to Rhazi’s method when...

  3. Beam measurements of the SPS longitudinal impedance

    CERN Document Server

    Lasheen, A

    2017-01-01

    Longitudinal instabilities are one of the main limitationsin the CERN SPS to reach the beam parameters requiredfor the High Luminosity LHC project. In preparation tothe SPS upgrade, possible remedies are studied by perform-ing macroparticle simulations using the machine impedancemodel obtained from electromagnetic simulations and mea-surements. To benchmark the impedance model, the resultsof simulations are compared with various beam measure-ments. In this study, the reactive part of the impedance wasprobed by measuring the quadrupole frequency shift withintensity, obtained from bunch length oscillations at mis-matched injection into the SPS. This method was appliedover many last years to follow up the evolution of the SPSimpedance, injecting bunches with the same bunch length.A novel approach, giving significantly more information,consists in varying the injected bunch length. The compari-son of these measurements with macroparticle simulationsallowed to test the existing model and identify some missingSPS i...

  4. Equivalent complex conductivities representing the effects of T-tubules and folded surface membranes on the electrical admittance and impedance of skeletal muscles measured by external-electrode method

    Science.gov (United States)

    Sekine, Katsuhisa

    2017-12-01

    In order to represent the effects of T-tubules and folded surface membranes on the electrical admittance and impedance of skeletal muscles measured by the external-electrode method, analytical relations for the equivalent complex conductivities of hypothetical smooth surface membranes were derived. In the relations, the effects of each tubule were represented by the admittance of a straight cable. The effects of the folding of a surface membrane were represented by the increased area of surface membranes. The equivalent complex conductivities were represented as summation of these effects, and the effects of the T-tubules were different between the transversal and longitudinal directions. The validity of the equivalent complex conductivities was supported by the results of finite-difference method (FDM) calculations made using three-dimensional models in which T-tubules and folded surface membranes were represented explicitly. FDM calculations using the equivalent complex conductivities suggested that the electrically inhomogeneous structure due to the existence of muscle cells with T-tubules was sufficient for explaining the experimental results previously obtained using the external-electrode method. Results of FDM calculations in which the structural changes caused by muscle contractions were taken into account were consistent with the reported experimental results.

  5. Optimization design of power efficiency of exponential impedance transformer

    International Nuclear Information System (INIS)

    Wang Meng; Zou Wenkang; Chen Lin; Guan Yongchao; Fu Jiabin; Xie Weiping

    2011-01-01

    The paper investigates the optimization design of power efficiency of exponential impedance transformer with analytic method and numerical method. In numerical calculation, a sine wave Jantage with hypothesis of rising edge equivalence is regarded as the forward-going Jantage at input of transformer, and its dominant angular frequency is determined by typical rise-time of actual Jantage waveforms. At the same time, dissipative loss in water dielectric is neglected. The numerical results of three typical modes of impedance transformation, viz. linear mode, saturation mode and steep mode,are compared. Pivotal factors which affect the power efficiency of exponential impedance transformer are discussed, and a certain extent quantitative range of intermediate variables and accordance coefficients are obtained. Finally, the paper discusses some important issues in actual design, such as insulation safety factor in structure design, effects of coupling capacitance on impedance calculation, and dissipative loss in water dielectric. (authors)

  6. Reliability of non-lethal assessment methods of body composition and energetic status exemplified by applications to eel (Anguilla anguilla) and carp (Cyprinus carpio)

    DEFF Research Database (Denmark)

    Klefoth, Thomas; Skov, Christian; Aarestrup, Kim

    2013-01-01

    tNon-lethal assessments of proximate body composition of fish can help unravelling the physiologicaland condition-dependent mechanisms of individual responses to ecological challenges. Common non-lethal methods designed to index nutrient composition in fish include the relative condition factor (Kn......),bioelectric impedance-based assessments of body composition (BIA), and microwave-based “fat” meters(FM). Previous studies have revealed mixed findings as to the reliability of each of these. We compared theperformance of Kn, BIA and FM at different temperatures to predict energetic status of the whole bodiesof live eel...... approach isthe most suitable method to non-lethally estimate energetic status in both, carp and eel, whereas BIA is oflimited use for energetic measurements in the same species, in contrast to other reports in the literature...

  7. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  8. Bioelectrical activity of limb muscles during cold shivering of stimulation of the vestibular apparatus

    Science.gov (United States)

    Kuzmina, G. I.

    1980-01-01

    The effects of caloric and electric stimulation of the vestibular receptors on the EMG activity of limb muslces in anesthetized cats during cold induced shivering involved flexor muscles alone. Both types of stimulation suppressed bioelectrical activity more effectively in the ipsilateral muscles. The suppression of shivering activity seems to be due to the increased inhibitory effect of descending labyrinth pathways on the function of flexor motoneurons.

  9. Lactose Bioelectricity on a Microbial Fuel Cell System Parallel Circuit Using Lactobacillus Bulgaricus

    OpenAIRE

    Putra, Adi; Nuryanto, Rahmad; Suyati, Linda

    2014-01-01

    Electrical energy needs in Indonesia is estimated to continue growing by 4.6% per year, and if there is nothing to be done to increase the production of electric energy, this figure will increase threefold by 2030. Microbial Fuel Cells (MFC) is one way to produce alternative electric energy by utilizing organic material as a substrate for bacterial metabolic activity that generate electricity. The aim of this study is to examine lactose bioelectricity in a parallel circuit MFC system using La...

  10. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  11. Bioelectric activity of childish brain in case of antenatal irradiation caused by Chernobyl accident

    International Nuclear Information System (INIS)

    Igumnov, S.A.; Drozdovich, V.V.; Shal'kevich, V.B.; Sekach, N.S.; Sivolobova, L.A.; Shal'kevich, L.V.; Chujko, Z.A.

    2002-01-01

    Formation of bioelectric activity of the brain was studied in two hundred and fifty children aged 6-7 and 10-12 yrs irradiated prenatally because of Chernobyl accident. The control group consisted of two hundred and fifty children the same age from 'clean' areas of Belarus. The examination included the visual and the computerized analyses of their EEGs as well as the psychiatric examination and the intellectual level assessment. Variants of the age norms and the synchronized borderline EEG were revealed in both groups of the children aged 6-7 yrs. A relevant decrease of the σ and Θ activities levels was registered in the children aged 10-12 yrs. In the both groups. The slow type of EEG in most cases was transformed into the age norm and the synchronized type of EEG. The bioelectric activity was not found to correlate with the dosimetric data. So, the changes of the bioelectric activity revealed showed a distinct age dependency and their frequency in the children exposed to antenatal irradiation did not differ significantly from that in the control group. (authors)

  12. Models of intracellular mechanisms of plant bioelectrical potentials caused by combined stimulation

    Directory of Open Access Journals (Sweden)

    D. V. Chernetchenko

    2014-10-01

    Full Text Available This paper deals with bioelectrical potentials of the plants recorded during different types of stimuli and combined stimulus as well. All registrations were observed on the leaves of the corn. We used different stimuli, such as cold, heat, photo- and electrical stimulation, and certain combination of this stimuli. Hardware and software system for automated recording of bioelectrical potentials has been successfully used in this work. We proposed the universal pattern of bioelectrical potentials’ recording which allowed to detect the response of the biological object to different stimuli and various combinations of these stimuli. This pattern can be used for the deeper understanding of biological mechanisms of electrical potentials’ generation in cells and discovering of processes of accommodation of whole organisms to these stimuli. Integrated system of recording and biometrical processing was used for analysis of corn leaves electrical responses to the thermal stimuli. The dynamics of these potentials was studied, with the quantitative analysis of the potential level stabilization.We calculated the ratio of amplitude of response potentials to the first response amplitude. Mathematical models of the plant cell were used for studying of intracellular mechanisms of biopotentials gereration. As a result of modeling, we revealed that electrical response of the cells was based on selectiveconductivity of cell membrane for Н+ and Ca2+ ions. Therefore, we showed the biophysical relation of plant potentials to underlying intracellular biophysical mechanisms during thermal and combined stimulation.

  13. Enhanced microbial reduction of vanadium (V) in groundwater with bioelectricity from microbial fuel cells

    Science.gov (United States)

    Hao, Liting; Zhang, Baogang; Tian, Caixing; Liu, Ye; Shi, Chunhong; Cheng, Ming; Feng, Chuanping

    2015-08-01

    Bioelectricity generated from the microbial fuel cell (MFC) is applied to the bioelectrical reactor (BER) directly to enhance microbial reduction of vanadium (V) (V(V)) in groundwater. With the maximum power density of 543.4 mW m-2 from the MFC, V(V) removal is accelerated with efficiency of 93.6% during 12 h operation. Higher applied voltage can facilitate this process. V(V) removals decrease with the increase of initial V(V) concentration, while extra addition of chemical oxygen demand (COD) has little effect on performance improvement. Microbial V(V) reduction is enhanced and then suppressed with the increase of conductivity. High-throughput 16S rRNA gene pyrosequencing analysis implies the accumulated Enterobacter and Lactococcus reduce V(V) with products from fermentative microorganisms such as Macellibacteroides. The presentation of electrochemically active bacteria as Enterobacter promotes electron transfers. This study indicates that application of bioelectricity from MFCs is a promising strategy to improve the efficiency of in-situ bioremediation of V(V) polluted groundwater.

  14. An equivalent body surface charge model representing three-dimensional bioelectrical activity

    Science.gov (United States)

    He, B.; Chernyak, Y. B.; Cohen, R. J.

    1995-01-01

    A new surface-source model has been developed to account for the bioelectrical potential on the body surface. A single-layer surface-charge model on the body surface has been developed to equivalently represent bioelectrical sources inside the body. The boundary conditions on the body surface are discussed in relation to the surface-charge in a half-space conductive medium. The equivalent body surface-charge is shown to be proportional to the normal component of the electric field on the body surface just outside the body. The spatial resolution of the equivalent surface-charge distribution appears intermediate between those of the body surface potential distribution and the body surface Laplacian distribution. An analytic relationship between the equivalent surface-charge and the surface Laplacian of the potential was found for a half-space conductive medium. The effects of finite spatial sampling and noise on the reconstruction of the equivalent surface-charge were evaluated by computer simulations. It was found through computer simulations that the reconstruction of the equivalent body surface-charge from the body surface Laplacian distribution is very stable against noise and finite spatial sampling. The present results suggest that the equivalent body surface-charge model may provide an additional insight to our understanding of bioelectric phenomena.

  15. VLF surface-impedance modelling techniques for coal exploration

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.; Thiel, D.; O' Keefe, S. [Central Queensland University, Rockhampton, Qld. (Australia). Faculty of Engineering and Physical Systems

    2000-10-01

    New and efficient computational techniques are required for geophysical investigations of coal. This will allow automated inverse analysis procedures to be used for interpretation of field data. In this paper, a number of methods of modelling electromagnetic surface impedance measurements are reviewed, particularly as applied to typical coal seam geology found in the Bowen Basin. At present, the Impedance method and the finite-difference time-domain (FDTD) method appear to offer viable solutions although both have problems. The Impedance method is currently slightly inaccurate, and the FDTD method has large computational demands. In this paper both methods are described and results are presented for a number of geological targets. 17 refs., 14 figs.

  16. Analytical model of impedance in elliptical beam pipes

    CERN Document Server

    Pesah, Arthur Chalom

    2017-01-01

    Beam instabilities are among the main limitations in building higher intensity accelerators. Having a good impedance model for every accelerators is necessary in order to build components that minimize the probability of instabilities caused by the interaction beam-environment and to understand what piece to change in case of intensity increasing. Most of accelerator components have their impedance simulated with finite elements method (using softwares like CST Studio), but simple components such as circular or flat pipes are modeled analytically, with a decreasing computation time and an increasing precision compared to their simulated model. Elliptical beam pipes, while being a simple component present in some accelerators, still misses a good analytical model working for the hole range of velocities and frequencies. In this report, we present a general framework to study the impedance of elliptical pipes analytically. We developed a model for both longitudinal and transverse impedance, first in the case of...

  17. Something different - caching applied to calculation of impedance matrix elements

    CSIR Research Space (South Africa)

    Lysko, AA

    2012-09-01

    Full Text Available of the multipliers, the approximating functions are used any required parameters, such as input impedance or gain pattern etc. The method is relatively straightforward but, especially for small to medium matrices, requires spending time on filling... of the computing the impedance matrix for the method of moments, or a similar method, such as boundary element method (BEM) [22], with the help of the flowchart shown in Figure 1. Input Parameters (a) Search the cached data for a match (b) A match found...

  18. On-line adaptive battery impedance parameter and state estimation considering physical principles in reduced order equivalent circuit battery models. Part 1. Requirements, critical review of methods and modeling

    Science.gov (United States)

    Fleischer, Christian; Waag, Wladislaw; Heyn, Hans-Martin; Sauer, Dirk Uwe

    2014-08-01

    Lithium-ion battery systems employed in high power demanding systems such as electric vehicles require a sophisticated monitoring system to ensure safe and reliable operation. Three major states of the battery are of special interest and need to be constantly monitored, these include: battery state of charge (SoC), battery state of health (capcity fade determination, SoH), and state of function (power fade determination, SoF). In a series of two papers, we propose a system of algorithms based on a weighted recursive least quadratic squares parameter estimator, that is able to determine the battery impedance and diffusion parameters for accurate state estimation. The functionality was proven on different battery chemistries with different aging conditions. The first paper investigates the general requirements on BMS for HEV/EV applications. In parallel, the commonly used methods for battery monitoring are reviewed to elaborate their strength and weaknesses in terms of the identified requirements for on-line applications. Special emphasis will be placed on real-time capability and memory optimized code for cost-sensitive industrial or automotive applications in which low-cost microcontrollers must be used. Therefore, a battery model is presented which includes the influence of the Butler-Volmer kinetics on the charge-transfer process. Lastly, the mass transport process inside the battery is modeled in a novel state-space representation.

  19. Transferring human impedance regulation skills to robots

    CERN Document Server

    Ajoudani, Arash

    2016-01-01

    This book introduces novel thinking and techniques to the control of robotic manipulation. In particular, the concept of teleimpedance control as an alternative method to bilateral force-reflecting teleoperation control for robotic manipulation is introduced. In teleimpedance control, a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller. This concept forms a basis for the development of the controllers for a robotic arm, a dual-arm setup, a synergy-driven robotic hand, and a compliant exoskeleton for improved interaction performance.

  20. Development of the impedance void meter

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Moon Ki; Song, Chul Hwa; Won, Soon Yeon; Kim, Bok Deuk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-06-01

    An impedance void meter is developed to measure the area-averaged void fraction. Its basic principle is based on the difference in the electrical conductivity between phases. Several methods of measuring void fraction are briefly reviewed and the reason why this type of void meter is chosen to develop is discussed. Basic principle of the measurement is thoroughly described and several design parameters to affect the overall function are discussed in detail. As example of applications is given for vertical air-water flow. It is shown that the current design has good dynamic response as well as very fine spatial resolution. (Author) 47 refs., 37 figs.

  1. Coupled Transmission Lines as Impedance Transformer

    DEFF Research Database (Denmark)

    Jensen, Thomas; Zhurbenko, Vitaliy; Krozer, Viktor

    2007-01-01

    A theoretical investigation of the use of a coupled line section as an impedance transformer is presented. We show how to properly select the terminations of the coupled line structures for effective matching of real and complex loads in both narrow and wide frequency ranges. The corresponding...... circuit configurations and the design procedures are proposed. Synthesis relations are derived and provided for efficient matching circuit construction. Design examples are given to demonstrate the flexibility and limitations of the design methods and to show their validity for practical applications...

  2. Optical approximation in the theory of geometric impedance

    International Nuclear Information System (INIS)

    Stupakov, G.; Bane, K.L.F.; Zagorodnov, I.

    2007-02-01

    In this paper we introduce an optical approximation into the theory of impedance calculation, one valid in the limit of high frequencies. This approximation neglects diffraction effects in the radiation process, and is conceptually equivalent to the approximation of geometric optics in electromagnetic theory. Using this approximation, we derive equations for the longitudinal impedance for arbitrary offsets, with respect to a reference orbit, of source and test particles. With the help of the Panofsky-Wenzel theorem we also obtain expressions for the transverse impedance (also for arbitrary offsets). We further simplify these expressions for the case of the small offsets that are typical for practical applications. Our final expressions for the impedance, in the general case, involve two dimensional integrals over various cross-sections of the transition. We further demonstrate, for several known axisymmetric examples, how our method is applied to the calculation of impedances. Finally, we discuss the accuracy of the optical approximation and its relation to the diffraction regime in the theory of impedance. (orig.)

  3. Validation of an Acoustic Impedance Prediction Model for Skewed Resonators

    Science.gov (United States)

    Howerton, Brian M.; Parrott, Tony L.

    2009-01-01

    An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

  4. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.

  5. Determination of Peukert's Constant Using Impedance Spectroscopy: Application to Supercapacitors.

    Science.gov (United States)

    Mills, Edmund Martin; Kim, Sangtae

    2016-12-15

    Peukert's equation is widely used to model the rate dependence of battery capacity, and has recently attracted attention for application to supercapacitors. Here we present a newly developed method to readily determine Peukert's constant using impedance spectroscopy. Impedance spectroscopy is ideal for this purpose as it has the capability of probing electrical performance of a device over a wide range of time-scales within a single measurement. We demonstrate that the new method yields consistent results with conventional galvanostatic measurements through applying it to commercially available supercapacitors. Additionally, the novel method is much simpler and more precise, making it an attractive alternative for the determination of Peukert's constant.

  6. Impedance technique for measuring dielectrophoretic collection of microbiological particles

    CERN Document Server

    Allsopp, D W E; Brown, A P; Betts, W B

    1999-01-01

    Measurement of the impedance change resulting from the collection of microbiological particles at coplanar electrodes is shown to be an effective and potentially quantitative method of detecting dielectrophoresis. Strong correlations between the frequency-dependent dielectrophoretic collection characteristics measured by impedance change and those observed using an established counting method based on image analysis have been obtained for Escherichia coli. In addition it is shown that the new electrical method can be used to sense dielectrophoretic collection of 19 nm diameter latex beads, particles too small to be resolved by conventional optical detection systems. (author)

  7. Impedance-matched Marx generators

    Directory of Open Access Journals (Sweden)

    W. A. Stygar

    2017-04-01

    Full Text Available We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs. The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  8. Impedance-matched Marx generators

    Science.gov (United States)

    Stygar, W. A.; LeChien, K. R.; Mazarakis, M. G.; Savage, M. E.; Stoltzfus, B. S.; Austin, K. N.; Breden, E. W.; Cuneo, M. E.; Hutsel, B. T.; Lewis, S. A.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Reisman, D. B.; Sceiford, M. E.; Wisher, M. L.

    2017-04-01

    We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with L C time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22 -Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19 -Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  9. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  10. Impedance analysis of acupuncture points and pathways

    International Nuclear Information System (INIS)

    Teplan, Michal; Kukucka, Marek; Ondrejkovicová, Alena

    2011-01-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  11. Journal bearing impedance descriptions for rotordynamic applications

    NARCIS (Netherlands)

    Childs, D.W.; Moes, H.; Leeuwen, van H.J.

    1977-01-01

    Bearing impedance vectors are introduced for plain journal bearings which define the bearing reaction force components as a function of the bearing motion. Impedance descriptions are developed directly for the approximate Ocvirk (short) and Sommerfeld (long) bearing solutions. The impedance vector

  12. Estimation of surface impedance using different types of microphone arrays

    DEFF Research Database (Denmark)

    Richard, Antoine Philippe André; Fernandez Grande, Efren; Brunskog, Jonas

    2017-01-01

    This study investigates microphone array methods to measure the angle dependent surface impedance of acoustic materials. The methods are based on the reconstruction of the sound field on the surface of the material, using a wave expansion formulation. The reconstruction of both the pressure...... and the particle velocity leads to an estimation of the surface impedance for a given angle of incidence. A porous type absorber sample is tested experimentally in anechoic conditions for different array geometries, sample sizes, incidence angles, and distances between the array and sample. In particular......, the performances of a rigid spherical array and a double layer planar array are examined. The use of sparse array processing methods and conventional regulariation approaches are studied. In addition, the influence of the size of the sample on the surface impedance estimation is investigated using both...

  13. Bioelectricity potential in Mato Grosso do Sul, Brazil; O potencial de bioeletricidade no Mato Grosso do Sul

    Energy Technology Data Exchange (ETDEWEB)

    Turdera, Eduardo Mirko Valenzuela [Universidade Federal da Grande Dourados (UFGD), Dourados, MS (Brazil). Faculdade de Ciencias Exatas e Tecnologicas], E-mail: eduardoturdera@ufgd.edu.br

    2009-07-01

    This paper presents the importance of bioelectricity power from renewable source in the power output of Mato Grosso do Sul (MS). The power energy capacity of MS could grow the next years due arrived of more of the thirty mills on medium term. This scenario will be very favorable because MS State will have conditions to meet power domestic market demand and to have significant surplus of electricity to export. Sugar cane crops are expanding and they could propitiate combined heat power (CHP or cogeneration) technology growth, we make an analysis about the share of the bioelectricity availability in MS power capacity installed. Bioelectricity could be good to MS as well as energy and economic aspects. (author)

  14. A Role for Bioelectric Effects in the Induction of Bystander Signals by Ionizing Radiation?

    Science.gov (United States)

    Mothersill, C.; Moran, G.; McNeill, F.; Gow, M.D.; Denbeigh, J.; Prestwich, W.; Seymour, C.B.

    2007-01-01

    The induction of “bystander effects” i.e. effects in cells which have not received an ionizing radiation track, is now accepted but the mechanisms are not completely clear. Bystander effects following high and low LET radiation exposure are accepted but mechanisms are still not understood. There is some evidence for a physical component to the signal. This paper tests the hypothesis that bioelectric or biomagnetic phenomena are involved. Human immortalized skin keratinocytes and primary explants of mouse bladder and fish skin, were exposed directly to ionizing radiation or treated in a variety of bystander protocols. Exposure of cells was conducted by shielding one group of flasks using lead, to reduce the dose below the threshold of 2mGy 60Cobalt gamma rays established for the bystander effect. The endpoint for the bystander effect in the reporter system used was reduction in cloning efficiency (RCE). The magnitude of the RCE was similar in shielded and unshielded flasks. When cells were placed in a Faraday cage the magnitude of the RCE was less but not eliminated. The results suggest that liquid media or cell-cell contact transmission of bystander factors may be only part of the bystander mechanism. Bioelectric or bio magnetic fields may have a role to play. To test this further, cells were placed in a Magnetic Resonance Imaging (MRI) machine for 10min using a typical head scan protocol. This treatment also induced a bystander response. Apart from the obvious clinical relevance, the MRI results further suggest that bystander effects may be produced by non-ionizing exposures. It is concluded that bioelectric or magnetic effects may be involved in producing bystander signaling cascades commonly seen following ionizing radiation exposure. PMID:18648606

  15. Viability of a Bioelectrical Signal Acquisition System Energized by Cellphone with NFC.

    Science.gov (United States)

    Kay, Marcel Seiji; Iaione, Fábio

    2015-01-01

    Currently, smartphones are used in various systems in the medical field due to the presence of various features, notably Near Field Communication (NFC). NFC utilizes communication technology and an energy supply based on electromagnetic induction. One of the most common medical tests is the electrocardiogram (ECG), through which various heart diseases can be diagnosed. The objective of this study is to evaluate the feasibility of providing power to a bioelectrical signal acquisition module using a mobile phone with NFC. After testing it was indicated that it is possible to construct a passive module to acquire ECG signals using NFC mobile phone.

  16. Validity of impedance-based predictions of total body water as measured by 2H dilution in African HIV/AIDS outpatients

    International Nuclear Information System (INIS)

    Diouf, Adama; Idohou Dossou, Nicole; Wade, Salimata; Gartner, Agnes; Sanon, Dominique Alexis; Bluck, Les; Wright, Antony

    2009-01-01

    Measurements of body composition are crucial in identifying HIV-infected patients at risk of malnutrition. No information is available on the validity of indirect body composition methods in African HIV-infected outpatients. Our aim was to test the validity of fifteen published equations, developed in whites, African-Americans and/or Africans who were or not HIV-infected, for predicting total body water (TBW) from bioelectrical impedance analysis (BIA) in HIV-infected patients. The second aim was to develop specific predictive equations. Thirty-four HIV-infected patients without antiretroviral treatment and oedema at the beginning of the study (age 39 (SD 7) years, BMI 18.7 (SD 3.7) kg/m2, TBW 30.4 (SD 7.2 kg) were measured at inclusion then 3 and 6 months later. In the resulting eighty-eight measurements, we compared TBW values predicted from BIA to those measured by 2H dilution. Range of bias values was 0.1-4.3, and errors showed acceptable values (2.2-3.4 kg) for fourteen equations and a high value (10.4) for one equation. Two equations developed in non-HIV-infected subjects showed non-significant bias and could be used in African HIV-infected patients. In the other cases, poor agreement indicated a lack of validity. Specific equations developed from our sample showed a higher precision of TBW prediction when using resistance at 1000kHz (1.7kg) than at 50kHz (2.3kg), this latter precision being similar to that of the valid published equations (2.3 and 2.8kg). The valid published or developed predictive equations should be cross-validated in large independent samples of African HIV-infected patients. (Authors)

  17. Validity of impedance-based equations for the prediction of total body water as measured by deuterium dilution in African women

    International Nuclear Information System (INIS)

    Dioum, Aissatou S.; Cisse, Aita; Wade, Salimata; Gartner, Agnes; Delpeuch, Francis; Maire, Bernard; Schutz, Yves

    2005-01-01

    Background: Little information is available on the validity of simple and indirect body-composition methods in non-Western populations. Equations for predicting body composition are population- specific, and body composition differs between blacks and whites. Objective:Wetestedthehypothesisthatthevalidityofequationsfor predicting total body water (TBW) from bioelectrical impedance analysis measurements is likely to depend on the racial background of the group from which the equations were derived. Design: The hypothesis was tested by comparing, in 36 African women, TBW values measured by deuterium dilution with those predicted by 23 equations developed in white, African American, or African subjects. These cross-validations in our African sample were also compared, whenever possible, with results from other studies in black subjects. Results: Errors in predicting TBW showed acceptable values (1.3- 1.9 kg) in all cases, whereas a large range of bias (0.2-6.1 kg) was observed independently of the ethnic origin of the sample from which the equations were derived. Three equations (2 from whites and 1 from blacks) showed nonsignificant bias and could be used in Africans. In all other cases, we observed either an overestimation or under estimation of TBW with variable bias values, regardless of racial background, yielding no clear trend for validity as a function of ethnic origin. Conclusions: The findings of this cross-validation study emphasize the need for further fundamental research to explore the causes of the poor validity of TBW prediction equations across populations rather than the need to develop new prediction equations for use in Africa. (Authors)

  18. Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results

    International Nuclear Information System (INIS)

    Prabhakar, Shyam

    1998-01-01

    A novel beam-based method for measuring the longitudinal impedance spectrum is demonstrated using experimental data from the PEP-II High Energy Ring (HER). The method uses a digital longitudinal feedback system from which the charge and synchronous phase are measured for every bucket. Calculation of the transfer function from fill shape to synchronous phase yields the impedance seen by the beam at revolution harmonics. The experimentally-derived longitudinal impedance function and lab measurements of the impedance of parked RF cavities are compared to suggest a mechanism for the occasional instability of low-order coupled bunch modes observed in the HER during commissioning in October 1997

  19. Impedance cardiography – optimization and efficacy evaluation of antihypertensive treatment

    Directory of Open Access Journals (Sweden)

    Katarzyna Panasiuk-Kamińska

    2016-09-01

    Full Text Available Background . Hypertension is a civilization disease which currently affects about 10.5 m people in Poland. The number of patients with diagnosed, untreated hypertension amounts to 18%, and as many as 45% of patients are treated ineffectively whereas only 26% are treated effectively. Impedance cardiography (IC is an important tool both in diagnostics and the treatment of hypertensive patients, particularly in the case of antihypertensive treatment resistance. This method allows for the individualized treatment of each patient on the basis of hemodynamic parameters, monitoring of hypertensive patients in the outpatient care setting, and the assessment of cardiovascular risk factors. Objectives . The aim of the study was to evaluate the efficacy of hypotensive medications in patients with hypertension using impedance cardiography. Material and methods. The study involved 60 hypertensive patients, treated with antihypertensives, who failed to achieve the required blood pressure values. The modification of hypertension therapy was based on EBM (evidence-based medicine and on hemodynamic parameters obtained using impedance cardiography. Results . It was found that high blood pressure therapy based on impedance cardiography parameters has a significant influence on blood pressure reduction compared to EM B-based therapy: below 140/90: 66.8 vs. 55.1% and below 130/80: 23.5 vs. 18.9%. Conclusions . On the basis of this study it was confirmed that impedance cardiography allows for a significant reduction of hypertension and the selection of the most effective therapeutic strategy, providing for the optimization and efficacy of hypertension treatment.

  20. Impedance planimetric description of normal rectoanal motility in humans

    DEFF Research Database (Denmark)

    Andersen, Inge S; Michelsen, Hanne B; Krogh, Klaus

    2007-01-01

    PURPOSE: Manometry and pressure-volume measurements are commonly used to study anorectal physiology. However, the methods are limited by several sources of error. Recently, a new impedance planimetric system has been introduced in a porcine model. It allows simultaneous determination of anorectal...... pressures and multiple rectal luminal cross-sectional areas. This study was designed to study normal human rectoanal motility by means of impedance planimetry with multiple rectal cross-sectional areas and rectal and anal pressure. METHODS: Twelve healthy volunteers (10 females), aged 24 to 53 years, were...... the experiment, the cross-sectional area at all channels showed strong cyclic contractile activity and the anal pressure increased by approximately 100 percent. CONCLUSIONS: The new rectal impedance planimetry system allows highly detailed description of rectoanal motility patterns. It has promise as a new...

  1. Raman and impedance spectroscopy methods of P{sub 2}O{sub 5}–Li{sub 2}O–Al{sub 2}O{sub 3} glass system doped with MgO

    Energy Technology Data Exchange (ETDEWEB)

    Jlassi, I., E-mail: ifa.jlassi@fst.rnu.tn [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Sdiri, N. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Elhouichet, H. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Ferid, M. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia)

    2015-10-05

    Highlights: • We have prepared a new lithium diphosphate glasses doped MgO. • Investigate structural and electrical properties at room temperature. • Investigate relation between structure and electrical conductivity of the glass. - Abstract: Lithium diphosphate glasses doped MgO was prepared via a melt quenching technique. The samples were characterized by X-ray diffraction (XRD), Raman and impedance spectroscopy. XRD spectra reflected the amorphous nature of the glasses Raman spectra show structural network modifications with the composition variations of the studied glasses. Raman spectra of the studied glasses contain also typical phosphate glasses bands. Thus the band at ∼698 cm{sup −1} assigned to symmetric stretching vibrations of P−O−P groups and that from ∼1168 cm{sup −1} is attributed to symmetric stretching motions of the non-bridging oxygen (NBO) atoms bonded to phosphorous atoms (PO{sub 2}) in phosphate tetrahedron. Electric properties were investigated using complex impedance spectroscopy in a frequency range from 40 Hz to 6 MHz at room temperature. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). Constant-phase elements (CPE) are used in equivalent electrical circuits for the fitting of experimental impedance data. The AC conductivity exhibited a Jonscher’s universal power law according with the relation σ(ω) = σ(0) + Aω{sup s} and it is observed that as the MgO content increases, frequency exponent (s) decreases.

  2. Online grid impedance estimation for single-phase grid-connected systems using PQ variations

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Rodriguez, Pedro

    2007-01-01

    algorithms are used in order to estimate the value of the grid impedance. The online grid impedance estimation method can be used for compliance with the anti-islanding standard requirements (IEEE1574, IEEE929 and VDE0126) and for adaptive control of the grid-connected converters. The proposed method...

  3. Observations involving broadband impedance modelling

    International Nuclear Information System (INIS)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances

  4. Assessment of bioelectrical activity of synergistic muscles during pelvic floor muscles activation in postmenopausal women with and without stress urinary incontinence: a preliminary observational study

    Directory of Open Access Journals (Sweden)

    Ptaszkowski K

    2015-09-01

    Full Text Available Kuba Ptaszkowski,1 Małgorzata Paprocka-Borowicz,2 Lucyna Słupska,2 Janusz Bartnicki,1,3 Robert Dymarek,4 Joanna Rosińczuk,4 Jerzy Heimrath,5 Janusz Dembowski,6 Romuald Zdrojowy6 1Department of Obstetrics, 2Department of Clinical Biomechanics and Physiotherapy in Motor System Disorders, Wroclaw Medical University, Wroclaw, Poland; 3Department of Obstetrics and Gynecology, Health Center Bitterfeld/Wolfen gGmbH, Bitterfeld-Wolfen, Germany; 4Department of Nervous System Diseases, 5Department of Gynaecology and Obstetrics, Faculty of Health Science, 6Department and Clinic of Urology, Faculty of Postgraduate Medical Training, Wroclaw Medical University, Wroclaw, Poland Objective: Muscles such as adductor magnus (AM, gluteus maximus (GM, rectus abdominis (RA, and abdominal external and internal oblique muscles are considered to play an important role in the treatment of stress urinary incontinence (SUI, and the relationship between contraction of these muscles and pelvic floor muscles (PFM has been established in previous studies. Synergistic muscle activation intensifies a woman’s ability to contract the PFM. In some cases, even for continent women, it is not possible to fully contract their PFM without involving the synergistic muscles. The primary aim of this study was to assess the surface electromyographic activity of synergistic muscles to PFM (SPFM during resting and functional PFM activation in postmenopausal women with and without SUI.Materials and methods: This study was a preliminary, prospective, cross-sectional observational study and included volunteers and patients who visited the Department and Clinic of Urology, University Hospital in Wroclaw, Poland. Forty-two patients participated in the study and were screened for eligibility criteria. Thirty participants satisfied the criteria and were categorized into two groups: women with SUI (n=16 and continent women (n=14. The bioelectrical activity of PFM and SPFM (AM, RA, GM was

  5. Fuzzy modeling of electrical impedance tomography images of the lungs

    International Nuclear Information System (INIS)

    Tanaka, Harki; Ortega, Neli Regina Siqueira; Galizia, Mauricio Stanzione; Borges, Joao Batista; Amato, Marcelo Britto Passos

    2008-01-01

    Objectives: Aiming to improve the anatomical resolution of electrical impedance tomography images, we developed a fuzzy model based on electrical impedance tomography's high temporal resolution and on the functional pulmonary signals of perfusion and ventilation. Introduction: Electrical impedance tomography images carry information about both ventilation and perfusion. However, these images are difficult to interpret because of insufficient anatomical resolution, such that it becomes almost impossible to distinguish the heart from the lungs. Methods: Electrical impedance tomography data from an experimental animal model were collected during normal ventilation and apnoea while an injection of hypertonic saline was administered. The fuzzy model was elaborated in three parts: a modeling of the heart, the pulmonary ventilation map and the pulmonary perfusion map. Image segmentation was performed using a threshold method, and a ventilation/perfusion map was generated. Results: Electrical impedance tomography images treated by the fuzzy model were compared with the hypertonic saline injection method and computed tomography scan images, presenting good results. The average accuracy index was 0.80 when comparing the fuzzy modeled lung maps and the computed tomography scan lung mask. The average ROC curve area comparing a saline injection image and a fuzzy modeled pulmonary perfusion image was 0.77. Discussion: The innovative aspects of our work are the use of temporal information for the delineation of the heart structure and the use of two pulmonary functions for lung structure delineation. However, robustness of the method should be tested for the imaging of abnormal lung conditions. Conclusions: These results showed the adequacy of the fuzzy approach in treating the anatomical resolution uncertainties in electrical impedance tomography images. (author)

  6. Scaling and the frequency dependence of Nyquist plot maxima of the electrical impedance of the human thigh.

    Science.gov (United States)

    Shiffman, Carl

    2017-11-30

    To define and elucidate the properties of reduced-variable Nyquist plots. Non-invasive measurements of the electrical impedance of the human thigh. A retrospective analysis of the electrical impedances of 154 normal subjects measured over the past decade shows that 'scaling' of the Nyquist plots for human thigh muscles is a property shared by healthy thigh musculature, irrespective of subject and the length of muscle segment. Here the term scaling signifies the near and sometimes 'perfect' coalescence of the separate X versus R plots into one 'reduced' Nyquist plot by the simple expedient of dividing R and X by X m , the value of X at the reactance maximum. To the extent allowed by noise levels one can say that there is one 'universal' reduced Nyquist plot for the thigh musculature of healthy subjects. There is one feature of the Nyquist curves which is not 'universal', however, namely the frequency f m at which the maximum in X is observed. That is found to vary from 10 to 100 kHz. depending on subject and segment length. Analysis shows, however, that the mean value of 1/f m is an accurately linear function of segment length, though there is a small subject-to-subject random element as well. Also, following the recovery of an otherwise healthy victim of ankle fracture demonstrates the clear superiority of measurements above about 800 kHz, where scaling is not observed, in contrast to measurements below about 400 kHz, where scaling is accurately obeyed. The ubiquity of 'scaling' casts new light on the interpretation of impedance results as they are used in electrical impedance myography and bioelectric impedance analysis.

  7. A model explaining synchronization of neuron bioelectric frequency under weak alternating low frequency magnetic field

    International Nuclear Information System (INIS)

    Moral, A. del; Azanza, María J.

    2015-01-01

    A biomagnetic-electrical model is presented that explains rather well the experimentally observed synchronization of the bioelectric potential firing rate (“frequency”), f, of single unit neurons of Helix aspersa mollusc under the application of extremely low frequency (ELF) weak alternating (AC) magnetic fields (MF). The proposed model incorporates to our widely experimentally tested model of superdiamagnetism (SD) and Ca 2+ Coulomb explosion (CE) from lipid (LP) bilayer membrane (SD–CE model), the electrical quadrupolar long range interaction between the bilayer LP membranes of synchronized neuron pairs, not considered before. The quadrupolar interaction is capable of explaining well the observed synchronization. Actual extension of our SD–CE-model shows that the neuron firing frequency field, B, dependence becomes not modified, but the bioelectric frequency is decreased and its spontaneous temperature, T, dependence is modified. A comparison of the model with synchronization experimental results of pair of neurons under weak (B 0 ≅0.2–15 mT) AC-MF of frequency f M =50 Hz is reported. From the deduced size of synchronized LP clusters under B, is suggested the formation of small neuron networks via the membrane lipid correlation. - Highlights: • Neuron pair synchronization under low frequency alternating (AC) magnetic field (MF). • Superdiamagnetism and Ca 2+ Coulomb explosion for AC MF effect in synchronized frequency. • Membrane lipid electrical quadrupolar pair interaction as synchronization mechamism. • Good agreement of model with electrophysiological experiments on mollusc Helix neurons

  8. A model explaining synchronization of neuron bioelectric frequency under weak alternating low frequency magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Moral, A. del, E-mail: delmoral@unizar.es [Laboratorio de Magnetismo, Departamento de Física de Materia Condensada and Instituto de Ciencia de Materiales, Universidad de Zaragoza and Consejo Superior de Investigaciones Científicas, 50009 Zaragoza (Spain); Laboratorio de Magnetobiología, Departamento de Anatomía e Histología, Facultad de Medicina, Universidad de Zaragoza, 50009 Zaragoza (Spain); Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid (Spain); Azanza, María J., E-mail: mjazanza@unizar.es [Laboratorio de Magnetobiología, Departamento de Anatomía e Histología, Facultad de Medicina, Universidad de Zaragoza, 50009 Zaragoza (Spain); Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid (Spain)

    2015-03-01

    A biomagnetic-electrical model is presented that explains rather well the experimentally observed synchronization of the bioelectric potential firing rate (“frequency”), f, of single unit neurons of Helix aspersa mollusc under the application of extremely low frequency (ELF) weak alternating (AC) magnetic fields (MF). The proposed model incorporates to our widely experimentally tested model of superdiamagnetism (SD) and Ca{sup 2+} Coulomb explosion (CE) from lipid (LP) bilayer membrane (SD–CE model), the electrical quadrupolar long range interaction between the bilayer LP membranes of synchronized neuron pairs, not considered before. The quadrupolar interaction is capable of explaining well the observed synchronization. Actual extension of our SD–CE-model shows that the neuron firing frequency field, B, dependence becomes not modified, but the bioelectric frequency is decreased and its spontaneous temperature, T, dependence is modified. A comparison of the model with synchronization experimental results of pair of neurons under weak (B{sub 0}≅0.2–15 mT) AC-MF of frequency f{sub M}=50 Hz is reported. From the deduced size of synchronized LP clusters under B, is suggested the formation of small neuron networks via the membrane lipid correlation. - Highlights: • Neuron pair synchronization under low frequency alternating (AC) magnetic field (MF). • Superdiamagnetism and Ca{sup 2+} Coulomb explosion for AC MF effect in synchronized frequency. • Membrane lipid electrical quadrupolar pair interaction as synchronization mechamism. • Good agreement of model with electrophysiological experiments on mollusc Helix neurons.

  9. History of Bioelectrical Study and the Electrophysiology of the Primo Vascular System

    Directory of Open Access Journals (Sweden)

    Sang Hyun Park

    2013-01-01

    Full Text Available Background. Primo vascular system is a new anatomical structure whose research results have reported the possibility of a new circulatory system similar to the blood vascular system and cells. Electrophysiology, which measures and analyzes bioelectrical signals tissues and cells, is an important research area for investigating the function of tissues and cells. The bioelectrical study of the primo vascular system has been reported by using modern techniques since the early 1960s by Bonghan Kim. This paper reviews the research result of the electrophysiological study of the primo vascular system for the discussion of the circulatory function. We hope it would help to study the electrophysiology of the primo vascular system for researchers. This paper will use the following exchangeable expressions: Kyungrak system = Bonghan system = Bonghan circulatory system = primo vascular system = primo system; Bonghan corpuscle = primo node; Bonghan duct = primo vessel. We think that objective descriptions of reviewed papers are more important than unified expressions when citing the papers. That said, this paper will unify the expressions of the primo vascular system.

  10. The Bioelectric Code: Reprogramming Cancer and Aging From the Interface of Mechanical and Chemical Microenvironments

    Directory of Open Access Journals (Sweden)

    Brian B. Silver

    2018-03-01

    Full Text Available Cancer is a complex, heterogeneous group of diseases that can develop through many routes. Broad treatments such as chemotherapy destroy healthy cells in addition to cancerous ones, but more refined strategies that target specific pathways are usually only effective for a limited number of cancer types. This is largely due to the multitude of physiological variables that differ between cells and their surroundings. It is therefore important to understand how nature coordinates these variables into concerted regulation of growth at the tissue scale. The cellular microenvironment might then be manipulated to drive cells toward a desired outcome at the tissue level. One unexpected parameter, cellular membrane voltage (Vm, has been documented to exert control over cellular behavior both in culture and in vivo. Manipulating this fundamental cellular property influences a remarkable array of organism-wide patterning events, producing striking outcomes in both tumorigenesis as well as regeneration. These studies suggest that Vm is not only a key intrinsic cellular property, but also an integral part of the microenvironment that acts in both space and time to guide cellular behavior. As a result, there is considerable interest in manipulating Vm both to treat cancer as well as to regenerate organs damaged or deteriorated during aging. However, such manipulations have produced conflicting outcomes experimentally, which poses a substantial barrier to understanding the fundamentals of bioelectrical reprogramming. Here, we summarize these inconsistencies and discuss how the mechanical microenvironment may impact bioelectric regulation.

  11. Spheromak Impedance and Current Amplification

    International Nuclear Information System (INIS)

    Fowler, T K; Hua, D D; Stallard, B W

    2002-01-01

    It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, τ REC , which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI TOR 2 /dt ∼ I 2 /τ REC - I TOR 2 /τ closed where I is the gun current, I TOR is the spheromak toroidal current and τ CLOSED is the ohmic decay time of the spheromak. Achieving high current amplification, I TOR >> I, requires τ REC CLOSED . For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that τ REC actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B ∝ I, or I TOR ∼ I. Program implications are discussed

  12. Virtual Impedance Based Stability Improvement for DC Microgrids with Constant Power Loads

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Sun, Kai; Huang, Lipei

    2014-01-01

    DC microgrid provides an efficient way to integrate different kinds of renewable energy sources with DC couplings. In this paper, in order to improve the stability of DC microgrids with constant power loads (CPLs), a virtual impedance based method is proposed. The CPLs have inherent instability....... To validate the stability with the above stabilizers in a DC microgrid with parallel interfacing converters and CPL, the impedance matching approach is employed. The output impedance of the source converter and input impedance of the load are calculated respectively, and the influence of droop control...

  13. Implementation and Test of On-line Embedded Grid Impedance Estimation for PV-inverters

    DEFF Research Database (Denmark)

    Asiminoaei, Lucian; Teodorescu, Remus; Blaabjerg, Frede

    2004-01-01

    to evaluate the grid impedance directly by the PV-inverter, providing a fast and low cost implementation. This principle theoretically provides a correct result of the grid impedance but when using it into the context of PV integration, different implementation issues strongly affect the quality...... of the results. This paper presents a new impedance estimation method including typical implementation problems encountered and it also presents adopted solutions for on-line grid impedance measurement. Practical tests on an existing PV-inverter validate the chosen solutions....

  14. Electrochemical Impedance Imaging via the Distribution of Diffusion Times

    Science.gov (United States)

    Song, Juhyun; Bazant, Martin Z.

    2018-03-01

    We develop a mathematical framework to analyze electrochemical impedance spectra in terms of a distribution of diffusion times (DDT) for a parallel array of random finite-length Warburg (diffusion) or Gerischer (reaction-diffusion) circuit elements. A robust DDT inversion method is presented based on complex nonlinear least squares regression with Tikhonov regularization and illustrated for three cases of nanostructured electrodes for energy conversion: (i) a carbon nanotube supercapacitor, (ii) a silicon nanowire Li-ion battery, and (iii) a porous-carbon vanadium flow battery. The results demonstrate the feasibility of nondestructive "impedance imaging" to infer microstructural statistics of random, heterogeneous materials.

  15. A Retrofit Technique for Kicker Beam-Coupling Impedance Reduction

    CERN Document Server

    Caspers, Friedhelm; Kroyer, T; Timmins, M; Uythoven, J; Kurennoy, S

    2004-01-01

    The reduction of the impedance of operational ferrite kicker structures may be desirable in order to avoid rebuilding such a device. Often resistively coated ceramic plates or tubes are installed for this purpose but at the expense of available aperture. Ceramic U-shaped profiles with a resistive coating fitting between the ellipse of the beam and the rectangular kicker aperture have been used to significantly reduce the impedance of the magnet, while having a limited effect on the available physical aperture. Details of this method, constraints, measurements and simulation results as well as practical aspects are presented and discussed.

  16. Evoked bioelectrical brain activity following exposure to ionizing radiation.

    Science.gov (United States)

    Loganovsky, K; Kuts, K

    2017-12-01

    The article provides an overview of modern physiological evidence to support the hypothesis on cortico limbic sys tem dysfunction due to the hippocampal neurogenesis impairment as a basis of the brain interhemispheric asym metry and neurocognitive deficit after radiation exposure. The importance of the research of both evoked poten tials and fields as a highly sensitive and informative method is emphasized.Particular attention is paid to cerebral sensor systems dysfunction as a typical effect of ionizing radiation. Changes in functioning of the central parts of sensory analyzers of different modalities as well as the violation of brain integrative information processes under the influence of small doses of ionizing radiation can be critical when determining the radiation risks of space flight. The possible long term prospects for manned flights into space, including to Mars, given the effects identified are discussed. Potential risks to the central nervous system during space travel comprise cognitive functions impairment, including the volume of short term memory short ening, impaired motor functions, behavioral changes that could affect human performance and health. The remote risks for CNS are considered to be the following possible neuropsychiatric disorders: accelerated brain aging, Alzheimer's disease and other types of dementia. The new radiocerebral dose dependent effect, when applied cog nitive auditory evoked potentials P300 technique with a possible threshold dose of 0.05 Gy, manifesting in a form of disruption of information processing in the Wernicke's area is under discussion. In order to identify neurophys iological biological markers of ionizing radiation further international researches with adequate dosimetry support are necessary. K. Loganovsky, K. Kuts.

  17. Impedance-based damage assessment using piezoelectric sensors

    Science.gov (United States)

    Rim, Mi-Sun; Yoo, Seung-Jae; Lee, In; Song, Jae-Hoon; Yang, Jae-Won

    2011-04-01

    Recently structural health monitoring (SHM) systems are being focused because they make it possible to assess the health of structures at real-time in many application fields such as aircraft, aerospace, civil and so on. Piezoelectric materials are widely used for sensors of SHM system to monitor damage of critical parts such as bolted joints. Bolted joints could be loosened by vibration, thermal cycling, shock, corrosion, and they cause serious mechanical failures. In this paper, impedance-based method using piezoelectric sensors was applied for real-time SHM. A steel beam specimen fastened by bolts was tested, and polymer type piezoelectric materials, PVDFs were used for sensors to monitor the condition of bolted joint connections. When structure has some damage, for example loose bolts, the impedance of PVDF sensors showed different tendency with normal structure which has no loose bolts. In the case of loose bolts, impedance values are decreased and admittance values are increased.

  18. Creating low-impedance tetrodes by electroplating with additives

    Science.gov (United States)

    Ferguson, John E.; Boldt, Chris; Redish, A. David

    2011-01-01

    A tetrode is a bundle of four microwires that can record from multiple neurons simultaneously in the brain of a freely moving animal. Tetrodes are usually electroplated to reduce impedances from 2-3 MΩ to 200-500 kΩ (measured at 1 kHz), which increases the signal-to-noise ratio and allows for the recording of small amplitude signals. Tetrodes with even lower impedances could improve neural recordings but cannot be made using standard electroplating methods without shorting. We were able to electroplate tetrodes to 30-70 kΩ by adding polyethylene glycol (PEG) or multi-walled carbon nanotube (MWCNT) solutions to a commercial gold-plating solution. The MWCNTs and PEG acted as inhibitors in the electroplating process and created large-surface-area, low-impedance coatings on the tetrode tips. PMID:21379404

  19. Pumping slots: impedances and power losses

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S [Maryland Univ., College Park, MD (United States). Dept. of Physics

    1996-08-01

    Contributions of pumping slots to the beam coupling impedances and power losses in a B-factory ring are considered. While their leading contribution is to the inductive impedance, for high-intensity machines with short bunches like e{sup +}e{sup -} B-factories the real part of the impedance and related loss factors are also important. Using an analytical approach we calculate the coupling impedances and loss factors due to slots in a ring with an arbitrary cross section of the vacuum chamber. Effects of the slot tilt on the beam impedance are also considered, and restrictions on the tilt angle are derived from limitations on the impedance increase. The power leakage through the slots is discussed briefly. The results are applied to the KEK B-factory. (author)

  20. Functionally graded materials for impedance matching in elastic media

    International Nuclear Information System (INIS)

    Chen, Shi; Zhang, Yinhong; Hao, Changchun; Lin, Shuyu; Fu, Zhiqiang

    2014-01-01

    When functionally graded material layers are inserted between two impedance mismatching media, passbands with extremely large bandwidths can appear in these layered systems. An accurate and effective iterative method is developed to deal with these layered systems with extremely large layer number.

  1. Functionally graded materials for impedance matching in elastic media

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shi; Zhang, Yinhong, E-mail: zyh5337@163.com; Hao, Changchun; Lin, Shuyu; Fu, Zhiqiang

    2014-01-03

    When functionally graded material layers are inserted between two impedance mismatching media, passbands with extremely large bandwidths can appear in these layered systems. An accurate and effective iterative method is developed to deal with these layered systems with extremely large layer number.

  2. Electrochemical Impedance Modeling of a Solid Oxide Fuel Cell Anode

    DEFF Research Database (Denmark)

    Mohammadi, R.; Søgaard, Martin; Ramos, Tania

    2014-01-01

    (TLM), which is suitably modified to account for the electrode microstructural details, is used for modeling the impedance arising from the electrochemical reactions. In order to solve the system of nonlinear equations, an in-house code based on the finite difference method was developed. Some...

  3. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...

  4. A note on the MUSIC algorithm for impedance tomography

    International Nuclear Information System (INIS)

    Hanke, Martin

    2017-01-01

    We investigate the MUSIC algorithm for the reconstruction of small (infinitesimal) inclusions inside a planar homogeneous object from discrete impedance tomography data within the framework of the gap electrode model. We provide a justification of the method whenever the number of electrodes exceeds 2( J   +  1) where J is the number of the inclusions to be found. (paper)

  5. MVAC Submarine cable, impedance measurements and analysis

    DEFF Research Database (Denmark)

    Arentsen, Martin Trolle; Expethit, Adrian; Pedersen, Morten Virklund

    2017-01-01

    influence the losses. Secondly, cable parameters such as component impedances, positive-, zero-sequence impedances and losses are measured for varying currents and frequencies. Zero sequence is measured for two setups, one with armour grounded, and with armour open to match CIGREs formula assumption......-sequence impedance is found between the measurements and the CIGRÉ formulas. It is concluded that the formulas are not accurate for the specific cable under test....

  6. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison...... to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View...

  7. Electrical impedance tomography of electrolysis.

    Directory of Open Access Journals (Sweden)

    Arie Meir

    Full Text Available The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT. The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.

  8. Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines: Real-Time Electrical Impedance Measurement at an Optimal Frequency

    Directory of Open Access Journals (Sweden)

    Yangkyu Park

    2016-01-01

    Full Text Available Purpose. To distinguish between normal (SV-HUC-1 and cancerous (TCCSUP human urothelial cell lines using microelectrical impedance spectroscopy (μEIS. Materials and Methods. Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results. The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p<0.001, was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p<0.001. Conclusion. The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF.

  9. Optimization design for the stepped impedance transformer based on the genetic algorithm

    International Nuclear Information System (INIS)

    Zou Dehui; Lai Wanchang; Qiu Dong

    2007-01-01

    This paper introduces the basic principium and mathematic model of the stepped impedance transformer, then puts the emphasis on comparing two kinds of design methods of the stepped impedance transformer. The design results are simulated by EDA, which indicates that genetic algorithm design is better than Chebyshev integrated design in the term of the most reflect coefficient's module. (authors)

  10. Estimation of non-cardiogenic pulmonary oedema using dual-frequency electrical impedance

    NARCIS (Netherlands)

    Raaijmakers, E.; Faes, T. J.; Meijer, J. M.; Kunst, P. W.; Bakker, J.; Goovaerts, H. G.; Heethaar, R. M.

    1998-01-01

    The study investigates the effects of non-cardiogenic oedema, especially the accumulation of protein in extracellular fluid, on thoracic impedance and proposes a new method of oedema measurement based on an impedance ratio from a dual-frequency measurement. In vitro measurements in a cell containing

  11. An islanding microgrid reactive power sharing scheme enhanced by programmed virtual impedances

    DEFF Research Database (Denmark)

    He, Jinwei; Li, Yun Wei; Guerrero, Josep M.

    2012-01-01

    harmonic currents. With the knowledge of feeder impedances, reactive power sharing performance can be enhanced by the regulation of DG unit output virtual impedance. The proposed method realizes accurate real and reactive power sharing in proportion to DG unit rated power. Simulated and experimental...

  12. Regional pressure volume curves by electrical impedance tomography in a model of acute lung injury

    NARCIS (Netherlands)

    Kunst, P. W.; Böhm, S. H.; Vazquez de Anda, G.; Amato, M. B.; Lachmann, B.; Postmus, P. E.; de Vries, P. M.

    2000-01-01

    OBJECTIVE: A new noninvasive method, electrical impedance tomography (EIT), was used to make pressure-impedance (PI) curves in a lung lavage model of acute lung injury in pigs. The lower inflection point (LIP) and the upper deflection point (UDP) were determined from these curves and from the

  13. Time-domain representation of frequency-dependent foundation impedance functions

    Science.gov (United States)

    Safak, E.

    2006-01-01

    Foundation impedance functions provide a simple means to account for soil-structure interaction (SSI) when studying seismic response of structures. Impedance functions represent the dynamic stiffness of the soil media surrounding the foundation. The fact that impedance functions are frequency dependent makes it difficult to incorporate SSI in standard time-history analysis software. This paper introduces a simple method to convert frequency-dependent impedance functions into time-domain filters. The method is based on the least-squares approximation of impedance functions by ratios of two complex polynomials. Such ratios are equivalent, in the time-domain, to discrete-time recursive filters, which are simple finite-difference equations giving the relationship between foundation forces and displacements. These filters can easily be incorporated into standard time-history analysis programs. Three examples are presented to show the applications of the method.

  14. Blocky inversion of multichannel elastic impedance for elastic parameters

    Science.gov (United States)

    Mozayan, Davoud Karami; Gholami, Ali; Siahkoohi, Hamid Reza

    2018-04-01

    Petrophysical description of reservoirs requires proper knowledge of elastic parameters like P- and S-wave velocities (Vp and Vs) and density (ρ), which can be retrieved from pre-stack seismic data using the concept of elastic impedance (EI). We propose an inversion algorithm which recovers elastic parameters from pre-stack seismic data in two sequential steps. In the first step, using the multichannel blind seismic inversion method (exploited recently for recovering acoustic impedance from post-stack seismic data), high-resolution blocky EI models are obtained directly from partial angle-stacks. Using an efficient total-variation (TV) regularization, each angle-stack is inverted independently in a multichannel form without prior knowledge of the corresponding wavelet. The second step involves inversion of the resulting EI models for elastic parameters. Mathematically, under some assumptions, the EI's are linearly described by the elastic parameters in the logarithm domain. Thus a linear weighted least squares inversion is employed to perform this step. Accuracy of the concept of elastic impedance in predicting reflection coefficients at low and high angles of incidence is compared with that of exact Zoeppritz elastic impedance and the role of low frequency content in the problem is discussed. The performance of the proposed inversion method is tested using synthetic 2D data sets obtained from the Marmousi model and also 2D field data sets. The results confirm the efficiency and accuracy of the proposed method for inversion of pre-stack seismic data.

  15. Resting potential, oncogene-induced tumorigenesis, and metastasis: the bioelectric basis of cancer in vivo

    Science.gov (United States)

    Lobikin, Maria; Chernet, Brook; Lobo, Daniel; Levin, Michael

    2012-12-01

    Cancer may result from localized failure of instructive cues that normally orchestrate cell behaviors toward the patterning needs of the organism. Steady-state gradients of transmembrane voltage (Vmem) in non-neural cells are instructive, epigenetic signals that regulate pattern formation during embryogenesis and morphostatic repair. Here, we review molecular data on the role of bioelectric cues in cancer and present new findings in the Xenopus laevis model on how the microenvironment's biophysical properties contribute to cancer in vivo. First, we investigated the melanoma-like phenotype arising from serotonergic signaling by ‘instructor’ cells—a cell population that is able to induce a metastatic phenotype in normal melanocytes. We show that when these instructor cells are depolarized, blood vessel patterning is disrupted in addition to the metastatic phenotype induced in melanocytes. Surprisingly, very few instructor cells need to be depolarized for the hyperpigmentation phenotype to occur; we present a model of antagonistic signaling by serotonin receptors that explains the unusual all-or-none nature of this effect. In addition to the body-wide depolarization-induced metastatic phenotype, we investigated the bioelectrical properties of tumor-like structures induced by canonical oncogenes and cancer-causing compounds. Exposure to carcinogen 4-nitroquinoline 1-oxide (4NQO) induces localized tumors, but has a broad (and variable) effect on the bioelectric properties of the whole body. Tumors induced by oncogenes show aberrantly high sodium content, representing a non-invasive diagnostic modality. Importantly, depolarized transmembrane potential is not only a marker of cancer but is functionally instructive: susceptibility to oncogene-induced tumorigenesis is significantly reduced by forced prior expression of hyperpolarizing ion channels. Importantly, the same effect can be achieved by pharmacological manipulation of endogenous chloride channels, suggesting

  16. Electrical impedance along connective tissue planes associated with acupuncture meridians

    Directory of Open Access Journals (Sweden)

    Hammerschlag Richard

    2005-05-01

    Full Text Available Abstract Background Acupuncture points and meridians are commonly believed to possess unique electrical properties. The experimental support for this claim is limited given the technical and methodological shortcomings of prior studies. Recent studies indicate a correspondence between acupuncture meridians and connective tissue planes. We hypothesized that segments of acupuncture meridians that are associated with loose connective tissue planes (between muscles or between muscle and bone visible by ultrasound have greater electrical conductance (less electrical impedance than non-meridian, parallel control segments. Methods We used a four-electrode method to measure the electrical impedance along segments of the Pericardium and Spleen meridians and corresponding parallel control segments in 23 human subjects. Meridian segments were determined by palpation and proportional measurements. Connective tissue planes underlying those segments were imaged with an ultrasound scanner. Along each meridian segment, four gold-plated needles were inserted along a straight line and used as electrodes. A parallel series of four control needles were placed 0.8 cm medial to the meridian needles. For each set of four needles, a 3.3 kHz alternating (AC constant amplitude current was introduced at three different amplitudes (20, 40, and 80 μAmps to the outer two needles, while the voltage was measured between the inner two needles. Tissue impedance between the two inner needles was calculated based on Ohm's law (ratio of voltage to current intensity. Results At the Pericardium location, mean tissue impedance was significantly lower at meridian segments (70.4 ± 5.7 Ω compared with control segments (75.0 ± 5.9 Ω (p = 0.0003. At the Spleen location, mean impedance for meridian (67.8 ± 6.8 Ω and control segments (68.5 ± 7.5 Ω were not significantly different (p = 0.70. Conclusion Tissue impedance was on average lower along the Pericardium meridian, but not

  17. Signal Processing for the Impedance Measurement on an Electrochemical Generator

    Directory of Open Access Journals (Sweden)

    El-Hassane AGLZIM

    2008-04-01

    Full Text Available Improving the life time of batteries or fuel cells requires the optimization of components such as membranes and electrodes and enhancement of the flow of gases [1], [2]. These goals could be reached by using a real time measurement on loaded generator. The impedance spectroscopy is a new way that was recently investigated. In this paper, we present an electronic measurement instrumentation developed in our laboratory to measure and plot the impedance of a loaded electrochemical generator like batteries and fuel cells. Impedance measures were done according to variations of the frequency in a larger band than what is usually used. The electronic instrumentation is controlled by Hpvee® software which allows us to plot the Nyquist graph of the electrochemical generator impedance. The theoretical results obtained in simulation under Pspice® confirm the choice of the method and its advantage. For safety reasons, the experimental preliminary tests were done on a 12 V vehicle battery, having an input current of 330 A and a capacity of 40 Ah and are now extended to a fuel cell. The results were plotted at various nominal voltages of the battery (12.7 V, 10 V, 8 V and 5 V and with two imposed currents (0.6 A and 4 A. The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical enables us to validate our electronic measurement instrumentation. Different sensors (temperature, pressure were placed around the device under test (DUT. These influence parameters were permanently recorded. Results presented here concern a classic loaded 12 V vehicle battery. The Nyquist diagram resulting from the experimental data confirms the influence of the load of the DUT on its internal impedance.

  18. Design of optimized impedance transformer for ICRF antenna in LHD

    Energy Technology Data Exchange (ETDEWEB)

    Saito, K., E-mail: saito@nifs.ac.jp [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan); Seki, T.; Kasahara, H.; Seki, R.; Kumazawa, R.; Nomura, G.; Shimpo, F.; Mutoh, T. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan)

    2013-10-15

    Highlights: ► We developed optimization method of impedance transformer for ICRF antenna. ► Power loss will be one-third with the optimized impedance transformer. ► Possibility of damage on the transmission line will be drastically reduced. ► High performance will be kept in the wide antenna impedance region. -- Abstract: A pair of ion cyclotron range of frequencies (ICRF) antennas in the large helical device (LHD), HAS antennas showed high efficiency in minority ion heating. However the low loading resistance must be increased to prevent breakdown in transmission line. Moreover, the voltage and the current around the feed-through must be reduced to protect it. For these purpose, we developed a design procedure of the impedance transformer for HAS antennas. To optimize the transformer, the inner conductors were divided into several segments and the radii of them were given discretely and independently. The maximum effective loading resistance was obtained by using all combinations of radii within the limitations of the voltage and current at the feed-through and the electric field on the transformer. To get a precise solution, this procedure was repeated several times by narrowing the range of radii of inner conductors. Then the optimized impedance transformer was designed by smoothing the radii of inner conductors. For the typical discharge, the voltage and current at the feed-through were reduced to the half of the original values with the same power. The effective loading resistance was increased to more than four times. High performance is expected in wide impedance region.

  19. Quantification of coating aging using impedance measurements

    NARCIS (Netherlands)

    Westing, E.P.M. van; Weijde, D.H. van der; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    This chapter shows the application results of a novel approach to quantify the ageing of organic coatings using impedance measurements. The ageing quantification is based on the typical impedance behaviour of barrier coatings in immersion. This immersion behaviour is used to determine the limiting

  20. High temperature impedance spectroscopy of barium stannate

    Indian Academy of Sciences (India)

    ... differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50–650 °C and frequency range of 10 Hz–13 MHz. The complex impedance plots at temperature ≥ 300 °C show ...