Impedance Method Research Articles

Influence of Ac-Signal Amplitude on the Dielectric Properties of Al-Tiw-Ptsi/N-Si Schottky Diodes

Influence of ac-signal amplitude on the dielectric properties of Al-TiW-PtSi/n-Si Schottky diode has been investigated at the room temperature and bias voltage in the range of -2V÷4V, when the amplitude of test signal (500 kHz) changed from 5mV to 1V. By the using impedance method have been obtained real ( εꞌ ) and imaginary (εꞌ) parts of dielectric constants and electric modul ( Mꞌ and Mꞌꞌ ) , loss tangent ( tanδ ), ac electrical conductivity ( σac ), the series resistance ( Rs ), On all dependences on voltage and amplitude of ac-signal , there is a jump in the value of the parameter in the range of voltage values 1-2V and 200mV It can be concluded that, at certain values, the amplitude of the ac-signal can significantly affect the interfacial polarization even at high frequencies.

Deep hybrid neural network-aided electromechanical impedance method for automated damage detection of lining concrete under freeze-thaw cycling

Deep hybrid neural network-aided electromechanical impedance method for automated damage detection of lining concrete under freeze-thaw cycling

Thermo-Acoustic Properties of Four Natural Fibers, Musa textilis, Furcraea andina, Cocos nucifera, and Schoenoplectus californicus, for Building Applications

Natural and bio-based construction materials such as bamboo, cork, or natural fiber composites offer a promising solution for enhancing the environmental sustainability of buildings. In this sense, the paper presents an experimental thermo-acoustic characterization of four common Ecuadorian natural fibers, abaca (Musa textilis), cabuya (Furcraea andina), coir (Cocos nucifera), and totora (Schoenoplectus californicus). Different densities were considered, from 85 kg/m3 (Cabuya) to 244 kg/m3 (totora), to thermo-acoustically characterize the samples built with these fibers, by means of the guarded-hot-plate (GHP) and impedance tube methods in-lab experimental benches. The exhaustive original characterization of the evaluated natural fiber composites showed a promising overall thermo-acoustic behavior. The thermal conductivity of the fibers was around 0.04–0.06 W/m·K and, therefore, comparable to other materials such as polystyrene, polyurethane, or aerogel that are already utilized for similar applications. On the other hand, the sound-absorption properties of the evaluated fibers are also very competitive, but strongly affected by the thickness of the sample, with noise reduction coefficient NRC ranging from 0.12 to 0.53. Consequently, the production and distribution of these materials in the Ecuadorian market for thermal insulation and acoustic conditioning constitute an alternative characterized by good technical performance, which, compared to synthetic composites used in the construction industry for similar duties, is ecological, sustainable, and has low built-in energy consumption.

Monitoring of cementitious materials hydration using 2–2 cement-based piezoelectric transducers based on electromechanical impedance method

Monitoring cementitious materials hydration enhances construction efficiency by providing crucial information regarding the optimal timing for shoring removal and pre-stress transferring. In recent years, many scholars have utilized the lead zirconate titanate (PZT)-based electromechanical impedance method (EMI) to monitor the cementitious materials hydration process. However, conventional piezoelectric transducers are less compatible with cementitious materials. In addition, the currently commonly used statistical-based metrics lack a clear physical meaning. The 2–2 cement-based transducer (2−2), composed of multiple PZT elements, demonstrates excellent electromechanical performance and good compatibility with cementitious materials. In this study, the 2–2 was employed to monitor the cementitious materials hydration, and an electromechanical impedance model for describing the interaction between the 2–2 and the structure was presented. Taking into account both resonance frequency and peak value of the conductance signatures, an objective function was defined. Genetic algorithm (GA) was employed to minimize the disparity between theoretical and experimental results, thus extracting equivalent stiffness and damping. The empirical relationship between equivalent stiffness, damping, and compressive strength was established to predict the compressive strength. The experimental results show that for the same monitoring process, the normalized equivalent stiffness and damping extracted from different 2–2 sensors are in some agreement. It is more sensitive to hydration processes than statistical indicators. More importantly, the equivalent parameters have a clear physical meaning and can better portray the hydration process of the cementitious materials.

Adaptive variable impedance force/position hybrid control for large surface polishing

PurposeThis paper aims to propose a hybrid force/position controller based on the adaptive variable impedance.Design/methodology/approachFirst, the working space is divided into a force control subspace and a position subspace, the force control subspace adopts the position impedance control strategy. At the same time, the contact force model between the robot and the surface is analyzed in this space. Second, based on the traditional position impedance, the model reference adaptive control is introduced to provide an accurate reference position for the impedance controller. Then, the BP neural network is used to adjust the impedance parameters online.FindingsThe experimental results show that compared with the traditional PI control method, the proposed method has a higher flexibility, the dynamic response accommodation time is reduced by 7.688 s and the steady-state error is reduced by 30.531%. The overshoot of the contact force between the end of robot and the workpiece is reduced by 34.325% comparing with the fixed impedance control method.Practical implicationsThe proposed control method compares with a hybrid force/position based on PI control method and a position fixed impedance control method by simulation and experiment.Originality/valueThe adaptive variable impedance control method improves accuracy of force tracking and solves the problem of the large surfaces with robot grinding often over-polished at the protrusion and under-polished at the concave.

An Adaptive Virtual-Impedance-Based Current-Limiting Method with the Functionality of Transient Stability Enhancement for Grid-Forming Converter

Grid-forming (GFM) converters are regarded as the most promising solution for grid-connected converters of renewable energy due to their robustness against weak grids. However, attributable to their voltage source characteristics, GFM converters may experience overcurrent issues during large disturbances. The virtual impedance (VI) method is an effective method to solve this problem. Nevertheless, there exists a contradiction between the demands for VI posed by current limitations and transient stability. Firstly, the analytical equations of virtual impedance for limiting the fault steady-state current of a GFM converter with different depths of grid voltage sag are solved. On that basis, an adaptive method based on virtual impedance is proposed to limit the fault current. Moreover, the analytical equation of the output active power of the converter when using adaptive virtual impedance to limit the fault current is solved. On this basis, the effect of the virtual impedance ratio on the transient stability is investigated. Finally, an adaptive virtual-impedance-based current-limiting method with the functionality of transient stability enhancement for a grid-forming converter is innovatively proposed. The enhancement effect of the method is verified by the equal area criterion method and phase portrait method. Finally, the efficacy of the proposed method in limiting fault currents and enhancing transient stability is validated through hardware-in-the-loop (HIL) experiments.

Occurrence of Body Posture Abnormalities in Overweight and Obese Children Aged 5-6 Years-Pilot Study.

The study aimed to assess the occurrence of body posture disorders and their changes under the influence of a physioprophylactic program in children depending on body weight. In the examined children, the general and segmental body composition and body posture were determined using a physiotherapeutic assessment based on the Kasperczyk method. Mass, overall, and segmental body composition were determined using the bioelectrical impedance method using a TANITA body composition analyzer. The study group of 76 children was divided due to body weight disorders into Group I (n = 51), in which BMI and fat mass values were within the normative limits for age and gender, and Group II (n = 19), comprising children whose body weight exceeded the norm and/or fat mass exceeded normative values. The examined children underwent a physioprophylactic. The program was conducted by qualified physiotherapists for 12 weeks, once a week for 30 min. The therapeutic program was focused on physioprevention of being overweight and the correction of body posture. A distal distribution of fat mass was observed in the examined group. Asymmetry in the sagittal plane was found in 35% of children. No statistically significant differences were found in the presence of asymmetry in the sagittal plane between the groups. No statistically significant differences were found in the occurrence of posture irregularities between the groups. There were no changes in the weight and body posture of the examined children under the influence of the physiotherapy program. The lack of correlation in the examined group between body weight and posture irregularities in 5-6-year-olds may suggest the acquisition of posture defects as a consequence of the persistence of overweight or obesity.

Electrochemical Measurements of the In(III) Ions Electroreduction; the Influence of Mixed Adsorption Layers ACT-CTAB and ACT-SDS

Using voltammetric and impedance methods, the effects of mixed adsorption layers ACT-CTAB and ACT-SDS on the kinetics and mechanism of In(III) ions electroreduction were investigated. Acetazolamide (ACT) was shown to catalyse the course of the electrode reaction (according to the cap-pair rule). The multi-step nature of the In(III) ions electroreduction process in each of the systems studied in the chemical step of formation of the active In(III) - ACT complexes in the adsorption layer playing an important role is demonstrated. The presence of the cationic surfactant CTAB increases the dynamics of acceleration of the In(III) ion electroreduction process by ACT, while the presence of the anionic surfactant SDS inhibits this reaction.

Laser-driven ultrafast impedance spectroscopy for measuring complex ion hopping processes.

Superionic conductors, or solid-state ion-conductors surpassing 0.01 S/cm in conductivity, can enable more energy dense batteries, robust artificial ion pumps, and optimized fuel cells. However, tailoring superionic conductors requires precise knowledge of ion migration mechanisms that are still not well understood due to limitations set by available spectroscopic tools. Most spectroscopic techniques do not probe ion hopping at its inherent picosecond timescale nor the many-body correlations between the migrating ions, lattice vibrational modes, and charge screening clouds-all of which are posited to greatly enhance ionic conduction. Here, we develop an ultrafast technique that measures the time-resolved change in impedance upon light excitation, which triggers selective ion-coupled correlations. We also develop a cost-effective, non-time-resolved laser-driven impedance method that is more accessible for lab-scale adoption. We use both techniques to compare the relative changes in impedance of a solid-state Li+ conductor Li0.5La0.5TiO3 (LLTO) before and after UV to THz frequency excitations to elucidate the corresponding ion-many-body-interaction correlations. From our techniques, we determine that electronic screening and phonon-mode interactions dominate the ion migration pathway of LLTO. Although we only present one case study, our technique can extend to O2-, H+, or other charge carrier transport phenomena where ultrafast correlations control transport. Furthermore, the temporal relaxation of the measured impedance can distinguish ion transport effects caused by many-body correlations, optical heating, correlation, and memory behavior.

Non-destructive testing method of concrete based on piezoelectric sensor

Abstract This paper reviews the research and development of non-destructive techniques for monitoring concrete in the past. Active detection techniques, particularly Electro-Mechanical Impedance method and Wave Propagation method have been demonstrated to be effective in monitoring the concrete process. Electro-Mechanical Impedance method detects internal structural damage by analyzing the vibration characteristics of the structure by combining a piezoelectric transducer with the system to be measured. Compared to the Electro-Mechanical Impedance method, the fluctuation method uses two or more transducers, with one serving as an exciter to actively excite the signal. In contrast, the others form an array to receive the stress wave signal. This method offers several advantages, including the absence of dependence on an impedance meter and passive excitation, a simple operating principle, high response frequency, and high immunity to interference. In this work, the research status and progress in the field of non-destructive testing (NDT) of concrete are combined to summarize the results and refine the methodology of the research on the evaluation of concrete material properties and identification of structural damage; based on this, the bottlenecks, research difficulties and difficulties in the field are further outlined, and finally, the research outlook of NDT of concrete in response to these limitations is put forward.

Formulation of silver-loaded zeolitic imidazole framework-67 and its antibacterial coating on titanium surface for bioimplant applications

Artificial bioimplant infections caused by bacteria have been a persistent problem that requires re-surgery and is harmful to human tissue. A facile, inexpensive and stable antibacterial agent coating can be a significant alternative. The present study attempted to construct titanium (Ti) implant coated with silver loaded zeolitic imidazole framework (ZIF)-67 (Ag@ZIF-67)-chitosan composite through a casting technique. The as-prepared nanocomposite and its coating were subjected to various characterization techniques, including XPS, XRD, SEM, and TEM to understand the material properties. Antibacterial activity was assessed through a standard spread-plate method, and the cytocompatibility of the fabricated materials was examined upon the skin fibroblast (L929) cell line. Corrosion studies were performed by using anodic polarization and impedance methods. The bactericidal efficacy of the coating was validated in vivo by utilizing a subcutaneous mouse model. The nanocomposite and coating exhibited a significant antibacterial efficiency of above 95 % against S. aureus and E. coli as the combined release of Co2+ and Ag+ ions entailed cellular membrane disintegration. The Ag@ZIF-67 composite revealed negligible cytotoxicity and its coating exhibited strong bone cell attachment. In contrast to pure Ti surface, the Ag@ZIF-67-chitosan coated Ti exhibited a minor reduction in corrosion resistance and modifications to its passivation properties as a result of the formation of a galvanic cell. A remarkable antibacterial effect was evinced through the in vivo experiments demonstrating a complete disinfection with 99 % of S. aureus lysis with no bacterial growth in the nearby healthy tissues. In conclusion, the current results demonstrated that the fabricated Ag@ZIF-67 could be applied as an antibacterial coating material of Ti for bioimplant applications.

Retrospective Cross-Sectional Study of the Relationship of Thyroid Volume and Function with Anthropometric Measurements, Body Composition Analysis Parameters, and the Diagnosis of Metabolic Syndrome in Euthyroid People Aged 18-65.

Background and Objectives: The thyroid is a key endocrine gland for the regulation of metabolic processes. A body composition analysis (BCA) is a valuable complement to the assessment of body mass index, which is derived only from body weight and height. This cross-sectional retrospective study aimed to investigate the relationships between thyroid volume (TV) and thyroid function parameters, anthropometric measurements, BCA parameters, and the presence of metabolic syndrome (MetS) in adults without clinically overt thyroid disease. Material and Methods: This study involved 45 people (females: 57.8%; MetS: 28.9%) hospitalized for planned diagnostics without signs of acute illness or a deterioration of their health and without thyroid disease, who underwent thyroid ultrasound scans, biochemical tests to assess their thyroid function, MetS assessments, anthropometric measurements, and BCAs using the bioelectrical impedance method. Results: The TV was significantly larger in people with MetS compared to people without MetS. The TV was significantly higher and the serum thyrotropin (TSH) concentration was significantly lower in overweight and obese people than in normal and underweight people. The free triiodothyronine (FT3) serum concentration and TV were correlated with waist circumference and some parameters of the BCA, and the FT3 concentration was also correlated with the body mass index, waist-hip ratio, and waist-height ratio. No significant correlations were found between the FT4 and TSH and the results of the anthropometric and BCA measurements. Conclusions: Even in a population of euthyroid patients without clinically overt thyroid disease, there were some significant relationships between the volume and function of the thyroid gland and the results of their anthropometric parameters, BCAs, and the presence of MetS features.

Development of a passive wireless sensor for fluidic detection and characterization utilizing the PCB-based coplanar electrode (PCE) configuration

During the global economic development, there's a growing focus on healthcare, especially in the advancement of medical diagnostic technologies, with a significant emphasis on glucose level evaluation. Glucose biosensors, predominantly electrochemical, have evolved over four generations, with the first three being enzyme-based and known for sensitivity and cost-effectiveness, albeit with limitations due to environmental susceptibility and reliance on enzyme activity. Recent advancements in non-invasive blood glucose monitoring, utilizing optical, microwave, and electrochemical techniques, offer diverse benefits without tissue penetration. Among these, impedance sensing stands out due to its flexibility and integration capability in handheld devices. This study proposes a wireless passive impedance method leveraging the inductor-capacitor (LC) sensing technique and PCB (Printed Circuit Board)-based coplanar electrode (PCE) configuration for fluidic sample detection. The proposed system integrates a two-coplanar-electrode layout with a square spiral inductor to assess fluidic conductivity and characterize various fluid types within samples. The effectiveness of this configuration was validated through experiments with NaCl and glucose solutions, confirming the feasibility of integrating PCB-based coplanar electrodes into conventional LC passive wireless sensing designs for fluidic detection and characterization.

Resilient and Sustainable Structures through EMI-Based SHM Evaluation of an Innovative C-FRP Rope Strengthening Technique

Reinforced Concrete (RC) members in existing RC structures are susceptible to shear-critical due to their under-reinforced design. Thus, implementing a retrofitting technique is essential to eliminate the casualties that could arise from sudden and catastrophic collapses due to these members’ brittleness. Among other proposed techniques, using Carbon-Fiber Reinforced Polymers (C-FRP) ropes to increase the shear strength of RC structural elements has proved to be a promising reinforcement application. Moreover, an Electro-Mechanical Impedance (EMI-based) method using Lead Zirconate Titanate (PZT-enabled) was employed to assess the efficiency of the strengthening scheme. Initially, the proposed technique was applied to C-FRP rope under the subjection of pullout testing. Thus, a correlation of the rope’s tensile strength with the EMI responses of the PZT patch was achieved using the Root Mean Square Deviation (RMSD) metric index. Thereafter, the method was implemented to the experimentally acquired data of C-FRP ropes, used as shear reinforcement in a rectangular deep beam. The ropes were installed using the Embedded Through Section (ETS) scheme. Furthermore, an approach to evaluate the residual shear-bearing capacity based on the EMI responses acquired by being embedded in and bonded to the ropes’ PZTs was attempted, demonstrating promising results and good precision compared to the analytical prediction of the C-FRP ropes’ shear resistance contribution.

Effects of 5-week detraining period on body composition of professional soccer players

Purpose. The aim of the study was to examine the effects of five weeks detraining period on body composition changes in elite professional Indonesian male soccer players. Material and methods. The body composition of 24 top-level male soccer players (age: 26.33 ± 4.06 years) competing in First League of Indonesia was measured before and after the 5-weeks detraining period. Body composition variables, including body mass, body fat percentage, fat-free mass, and total body water percentage, were measured using the bioelectrical impedance method. The results. The paired samples T-test showed significant changes in the means of body composition variables for body fat percentage, fat-free mass, and total body water percentage. Mean values for body fat percentage increased during the detraining period from 10.87 ± 2.47% to 11.98 ± 2.75% (10.3%). A decrease in mean values for fat-free mass (61.34 ± 5.74 kg to 59.80 ± 6.22; 2.49%) and total body water percentage (from 65.13 ± 1.84% to 64.40 ± 1.99%; 1.12%) was observed. No significant changes occurred in body mass (from 69.05 ± 8.07 kg to 69.05 ± 8.48 kg; 0.04%) from initial to final testing. Conclusions. Since there was a significant difference in body fat percentage, fat-free mass, and total body water percentage% before and after detraining period., it is suggested that 5 weeks of detraining period. for the professional soccer players may not be necessary, and the duration should be shortened to maintain body composition status.

Evaluation of darbepoetin therapy on platelet count and function in healthy cats and cats with surgically induced chronic kidney disease.

To evaluate the effects of darbepoetin on platelet population and reactivity in healthy cats (HCs) and azotemic cats with remnant kidney (RK) model-induced chronic kidney disease. 12 purpose-bred domestic shorthair cats (n = 6 HCs and n = 6 RK). In this pilot study, all cats received darbepoetin (1 µg/kg, SC) on days 0, 7, and 14. Blood was sampled at baseline and on days 3, 10, 15, 17, 20, and 21. At each time point, a CBC was performed, platelet aggregometry was assessed by impedance and optical methods, and platelet P-selectin (CD62P) was quantified before and after thrombin stimulation. Additionally, reticulated platelets were quantified using both thiazole orange staining and proprietary analysis by the CBC analyzer. For RK cats, systemic blood pressure (BP) was serially measured. No adverse effects of darbepoetin were seen. There was no statistically significant change in platelet count between or within groups at any time point. Hematocrit increased significantly over time in the RK but not the HC group. RBC reticulocyte numbers in both groups increased over time. Reticulated platelet percentage did not increase in either group. Differences in platelet reactivity within or between groups were not seen in the aggregometry or flow cytometric assessments. In RK cats, indirect BP did not significantly change during the study. This preliminary investigation did not find evidence that darbepoetin administration impacted platelet number, reactivity, nor reticulated platelet count. Anemic RK cats experienced increased hematocrit and RBC reticulocytes as expected with darbepoetin therapy.

A wideband harmonic self-mitigation controller of the VSG-based islanded microgrid without harmonic extraction

In virtual synchronous generator (VSG)-based islanded microgrid, voltage harmonics induced by nonlinear loads seriously degrade system power quality. Existing harmonic mitigation controllers mainly rely on the extracted harmonic components to control, and generally have the weakness that can only mitigate harmonics with known frequencies. To better improve the power quality of the islanded microgrid, a wideband harmonic self-mitigation controller (WHSMC) is proposed in this paper, which can effectively mitigate wideband voltage harmonics above the fundamental frequency without extracting harmonics. Firstly, based on the impedance method, the reason why nonlinear loads will cause voltage harmonics in the islanded microgrid is analyzed in detail. Secondly, by establishing the impedance model of VSG with the proposed WHSMC, the mechanism how the proposed WHSMC mitigates voltage harmonics without knowing the harmonic frequency in advance is theoretically revealed. Finally, the effectiveness of the proposed WHSMC is verified through simulation and experimental results. The experiments indicate that the voltage total harmonic distortion (THD) can decrease from 7.02 % to 3.41 % under nonlinear load disturbance and from 8.27 % to 3.99 % under pulse load disturbance.

Estimation of sound absorption coefficient at modal frequencies using decay time measurements and eigenvalue model in a small room

Measuring the sound absorption coefficient in a small reverberation room below the Schroeder frequency is a challenging task and the results are subject to a high degree of uncertainty. Recent research shows that the low-frequency acoustic properties of the enclosure and the test sample should be characterized by quantities that describe the modal sound field. The aim of this paper is to present a method for estimating the absorption coefficient of a test sample at modal frequencies in the low frequency range and to demonstrate its applicability in a small room. The hybrid inverse approach is based on eigenvalue measurement data coupled with a finite element model to estimate the sound-absorbing properties of a small room and the test sample. The method was tested experimentally and the results were consistent with those of the long impedance tube method. The applicability of the proposed method was further demonstrated by the in-situ characterization of different acoustic samples in the low frequency range.

Damping monitoring methods during ultrasonic fatigue testing: A comparative study.

Ultrasonic fatigue testing is quite a useful tool for exploring the high-cycle and very-high-cycle fatigue properties of materials. Damping monitoring has been proved to be fairly effective in indicating the generated defects or damage in the testing specimen. In this work, two damping monitoring methods are comparatively studied, i.e., our recently proposed quantitative electromechanical impedance method and the traditional vibration-free decay method. Industrial pure copper and 6061 aluminum alloy are used for fatigue testing and damping monitoring. To exclude the differences of temperature effect on the testing system, the same duty ratio of 15.4% is employed in the ultrasonic fatigue testing. The results show that both methods can effectively monitor the system damping during testing and the damping evolution process just before failure. Specifically, the free decay method can obtain more damping data and has advantages in monitoring metals, such as aluminum alloys, whose fracture process is very quick. However, the system damping obtained by free decay is strongly dependent on the testing stresses and signal processing and is thus not suitable for failure prediction of specimens. In comparison, the system damping obtained by using the quantitative electromechanical impedance method is independent of the testing stresses. Thus, a definite relationship between the system damping and specimen's internal friction can be established. However, tens of seconds are required for accurate damping measurement using the quantitative electromechanical impedance method, leading to a low duty ratio of the ultrasonic fatigue testing. In practical, both the methods are suggested for monitoring of early damage during ultrasonic fatigue testing.

Analysis of Fault Locations Using the Impedance Method on the GIS 150 kV Transmission Line Karang Pilang Surabaya

Transmission lines often experience difficulties in determining the location of interference, due to the length of the transmission line. This interference can be secured by using relays, one of which is a distance relay, this tool secures the zone 1, zone 2 and zone 3 areas on the transmission line. Apart from relays, there is also a tool to determine the fault distance, namely a fault locator. These two tools are examples of protection on transmission lines. The method used in this research uses the impedance method to determine the distance the fault occurs and the settings on the distance relay. This technique is often used in electric power systems and is very effective for transmission lines, such as those in Karang Pilang, because of its ability to detect disturbances in transmission lines and equipment. Based on the analysis results, calculating the fault distance using the impedance method shows that the calculated value is very close to the distance measured by the fault finder. Specifically when a short circuit occurs, the impedance method calculates a distance of 14.35 km, while the fault locator measures it at 14.59 km with a margin of error of 1.5%.