Current Measurement Methods Research Articles

Research on Alternating Current Field Measurement Method for Buried Defects of Titanium Alloy Aircraft Skin.

Titanium alloys are extensively used in the manufacturing of key components in aerospace engines and aircraft structures due to their excellent properties. However, aircraft skins in harsh operating environments are subjected to long-term corrosion and pressure concentrations, which can lead to the formation of cracks and other defects. In this paper, a detection probe is designed based on the principle of alternating current field measurement, which can effectively detect both surface and buried defects in thin-walled titanium alloy plates. A finite element simulation model of alternating current field measurement detection for buried defects in thin-walled TC4 titanium alloy plates is established using COMSOL 5.6 software. The influence of defect length, depth, and excitation frequency on the characteristic signals is investigated, and the detection probe is optimized. Simulation and experimental results demonstrate that the proposed detection probe exhibits high detection sensitivity to varying lengths and depths of buried defects, and can detect small cracks with a length of 3 mm and a burial depth of 2 mm, as well as deep defects with a length of 10 mm and a burial depth of 4 mm. The feasibility of this probe for detecting buried defects in titanium alloy aircraft skin is confirmed.

Non-invasive methods for heart rate measurement in fish based on photoplethysmography.

Heart rate is a crucial physiological indicator for fish, but current measurement methods are often invasive or require delicate manipulation. In this study, we introduced two non-invasive and easy-to-operate methods based on photoplethysmography, namely reflectance-type photoplethysmography (PPG) and remote photoplethysmography (rPPG), which we applied to the large yellow croaker (Larimichthys crocea). PPG showed perfect synchronization with electrocardiogram (ECG), with a Pearson's correlation coefficient of 0.99999. For rPPG, the results showed good agreement with ECG. Under active provision of green light, the Pearson's correlation coefficient was 0.966, surpassing the value of 0.947 under natural light. Additionally, the root mean square error was 0.810, which was lower than the value of 1.30 under natural light, indicating not only that the rPPG method had relatively high accuracy but also that green light may have the potential to further improve its accuracy.

Non-Contact Current Measurement for Three-Phase Rectangular Busbars Using TMR Sensors.

This paper proposes a non-contact current measurement method for three-phase rectangular busbars based on TMR (tunneling magneto-resistance) sensors, due to their advantages of large dynamic range, wide bandwidth, light weight, and easy installation. A non-contact current sensor composed of only three TMR sensors is developed and the TMR sensors are respectively placed at a location with a certain distance from the surface of each rectangular busbar to measure the magnetic fields generated by the busbar currents. To calibrate the developed current sensor, i.e., to establish the relationship between the magnetic fields measured by the TMR sensors and the currents flowing in the three-phase rectangular busbars, we designed a thyristor-controlled resistive load as a calibrator, which is connected to a downstream branch of the distribution cabinet. By switching the resistive load, a calibration current, which can be identified from the background current, is generated in one rectangular busbar and its value is measured at the location of the calibrator, and transmitted wirelessly to the location of the TMR sensors. A new and robust method is proposed to extract the voltage components, corresponding to the calibration current, from the voltage waveforms of the TMR sensors. By calculating the proportional coefficients between the calibration currents and the extracted voltage components, online calibration of the current sensor is achieved. We designed and implemented a current measurement system consisting of a current sensor using TMR sensors, a thyristor-controlled resistive load for current sensor calibration, and a data acquisition circuit based on a multi-channel analog-to-digital converter (ADC). Current measurement experiments were performed in a practical distribution cabinet installed in our laboratory. Compared to the measurement results using a commercial current probe with an accuracy of 1%, the relative error of the measured currents in RMS is less than 2.5% and the phase error is less than 1°, while the nonlinearity error of the current sensor is better than 0.8%.

DETERMINING THE ACCURACY OF THE SMART BRACE USING MULTI-FREQUENCY BIOIMPEDANCE ANALYSIS TO MEASURE KNEE SWELLING

Knee swelling is common after injury or surgery, resulting in pain, restricted range of movement and limited mobility. Accurately measuring knee swelling is critical to assess recovery. However, current measurement methods are either unreliable or expensive [1,2]. Therefore, a new measurement method is developed. This wearable (the ‘smart brace’) has shown the ability to distinguish a swollen knee from a not swollen knee using multi-frequency-bio impedance analysis (MF-BIA) [3].This study aimed to determine the accuracy of this smart brace. The study involved 25 usable measurements on patients treated for unilateral knee osteoartritis with a 5mL injection of Lidocaïne + DepoMedrol (1:4). MF-BIA measurements were taken before and after the injection, both on the treated and untreated knee. The smart brace accurately measured the effect of the injection by a decrease in resistance of up to 2.6% at 100kHz (p<0.01), where commonly used gel electrodes were unable to measure the relative difference. Remarkably, both the smart brace and gel electrodes showed a time component in the MF-BIA measurements.To further investigate this time component, 10 participants were asked to lie down for 30 minutes, with measurements taken every 3 minutes using both gel electrodes and the smart brace on both legs. The relative change between each time step was calculated to determine changes over time. The results showed presence of a physiological aspect (settling of knee fluids), and for the brace also a mechanical aspect (skin-electrode interface) [4]. The mechanical aspect mainly interfered with reactance values.Overall, the smart brace is a feasible method for quantitatively measuring knee swelling as a relative change over time. However, the skin-electrode interface should be improved for reliable measurements at different moments in time. The findings suggest that the smart brace could be a promising tool for monitoring knee swelling during rehabilitation.

A Novel Method for DC Current Measurement Using Current Transformer

A Novel Method for DC Current Measurement Using Current Transformer

Flash Drought Typologies and Societal Impacts: A Worldwide Review of Occurrence, Nomenclature, and Experiences of Local Populations

Abstract Flash droughts, characterized by rapid onset and intensification, are increasingly occurring as a consequence of climate change and rising temperatures. However, existing hydrometeorological definitions fail to encompass the full range of flash droughts, many of which have distinct local physical attributes. Consequently, these events often go undetected or unforecast in generic global flash drought assessments and are underrepresented in research. To address this gap, we conducted a comprehensive survey to gather information on local nomenclature, characteristics, and impacts of flash droughts worldwide. The survey revealed the widespread occurrence of these phenomena, highlighting their underresearched nature. By analyzing case studies, through literature review often in local languages to unearth elusive studies, we identified five different types of flash droughts based on their specific characteristics. Our study aims to increase awareness about the complexity and diverse impacts of flash droughts, emphasizing the importance of considering regional contexts and the vulnerability of affected populations. The reported impacts underscore the need for better integration of all flash drought types in drought research, monitoring, and management. Monitoring a combination of indicators is crucial for timely detection and response to this emerging and escalating threat. Significance Statement This study aims to better understand flash droughts worldwide and their varying characteristics and impacts. We surveyed the experiences of people affected by flash droughts and then examined a wide range of literature, including non-English and nonacademic sources. This helped us understand how flash droughts can differ from those commonly studied in the United States and China. We identified and described five types of flash droughts, some of which may not be detected by current drought measurement methods. It is crucial to include all types of flash droughts in drought monitoring systems and management plans, as they are expected to become more common due to global warming. We can then better prepare for and reduce the impacts of this growing threat.

Accurate Current Measurement Method in High Frequency Hybrid Switch Test and Application

Accurate Current Measurement Method in High Frequency Hybrid Switch Test and Application

Estimation of Stiffness Maps in Deforming Cells Through Optical Flow with Bounded Curvature.

The stiffness of cells and of their nuclei is a biomarker of several pathological conditions. Current measurement methods rely on invasive physical probes that yield one or two stiffness values for the whole cell. However, the internal distribution of cells is heterogeneous. We propose a framework to estimate maps of intracellular and intranuclear stiffness inside deforming cells from fluorescent image sequences. Our scheme requires the resolution of two inverse problems. First, we use a novel optical-flow method that penalizes the nuclear norm of the Hessian to favor deformations that are continuous and piecewise linear, which we show to be compatible with elastic models. We then invert these deformations for the relative intracellular stiffness using a novel system of elliptic PDEs. Our method operates in quasi-static conditions and can still provide relative maps even in the absence of knowledge about the boundary conditions. We compare the accuracy of both methods to the state of the art on simulated data. The application of our method to real data of different cell strains allows us to distinguish different regions inside their nuclei.

A Wide-Range Self-Powered Current Measurement Method Based on Induced Current Multiplexing for Online Monitoring Devices in Transmission Lines

A Wide-Range Self-Powered Current Measurement Method Based on Induced Current Multiplexing for Online Monitoring Devices in Transmission Lines

Advancements in Methods of Classification and Measurement Used to Assess Tooth Mobility: A Narrative Review.

Evaluating tooth mobility is clinically significant, not only for diagnosing periodontal tissues but also in determining the overall periodontal treatment plan. Numerous studies related to tooth mobility have been conducted over the years, including the proposal of various classifications as well as the development of electronic devices for objective measurement. However, there is still no consensus on the measurement methods and criteria for assessing tooth mobility. In this study, we provide a comprehensive review of past and current tooth mobility classification and measurement methods. In order to propose a new method to intuitively evaluate tooth mobility based on previous studies, a digital approach capable of recording tooth micromovements induced by dynamic load should be considered.

Noninvasive Quantification of Contractile Dynamics in Cardiac Cells, Spheroids, and Organs-on-a-Chip Using High-Frequency Ultrasound.

Cell-based models that mimic in vivo heart physiology are poised to make significant advances in cardiac disease modeling and drug discovery. In these systems, cardiomyocyte (CM) contractility is an important functional metric, but current measurement methods are inaccurate and low-throughput or require complex setups. To address this need, we developed a standalone noninvasive, label-free ultrasound technique operating at 40-200 MHz to measure the contractile kinetics of cardiac models, ranging from single adult CMs to 3D microtissue constructs in standard cell culture formats. The high temporal resolution of 1000 fps resolved the beat profile of single mouse CMs paced at up to 9 Hz, revealing limitations of lower speed optical based measurements to resolve beat kinetics or characterize aberrant beats. Coupling of ultrasound with traction force microscopy enabled the measurement of the CM longitudinal modulus and facile estimation of adult mouse CM contractile forces of 2.34 ± 1.40 μN, comparable to more complex measurement techniques. Similarly, the beat rate, rhythm, and drug responses of CM spheroid and microtissue models were measured, including in configurations without optical access. In conclusion, ultrasound can be used for the rapid characterization of CM contractile function in a wide range of commonly studied configurations ranging from single cells to 3D tissue constructs using standard well plates and custom microdevices, with applications in cardiac drug discovery and cardiotoxicity evaluation.

A Whole-Segment Carbon Measurement Approach for Energy Systems Incorporating Knowledge Mapping Techniques

Abstract As the current carbon measurement method makes it difficult to reflect the time-space variability of carbon emission factors, it leads to the inability to clarify the carbon emission responsibility of grid-side losses. In this paper, starting from the internal power system, based on the power system carbon emission flow analysis theory and knowledge graph technology, a trend-tracking analytical algorithm based on the node conductivity matrix operation is proposed to solve the complex power allocation relationship between each generating unit and each node load, and between each generating unit and the line network loss. On the basis of this algorithm, the carbon flow tracking model of the whole power system is established according to the conversion relationship between the current and the carbon flow, and the analytical expressions of the carbon emission distribution among the power generation side, the load side and the line loss are obtained by combining with matrix operation, so as to measure the carbon emission measurement results of the whole power system and to provide data references for the responsibility sharing of carbon emission. Finally, simulation verification is carried out based on the actual system operation and load data for C city. The total amount of carbon emissions from electricity consumption is 98.8 million tCO2 when C city is used as the minimum spatial scale, while the total amount of carbon emissions from electricity consumption is 67.9 million tCO2, 14.0 million tCO2, 16.9 million tCO2, and the total amount of the three regions is 98.8 million tCO2, which is consistent with that calculated when C city is used as the minimum spatial scale. The calculation results are consistent in real-time. The carbon measurement method proposed in this paper can obtain higher spatial resolution carbon measurement results for electricity consumption.

RAPID AND AUTOMATED BODY MEASUREMENT OF CATTLE BASED ON STATISTICAL SHAPE MODEL

Abstract. The current methods of non-contact livestock body measurement directly deal with the low-quality point cloud data of livestock, which have low robustness and lack practicality. On the one hand, the success rate of keypoint detection for livestock body measurement is low. Due to the severe occlusion and noise in the point cloud data, body measurements of some data cannot be performed. On the other hand, the key frames need to be manually selected from the point cloud sequence during processing. Inspired by the work of 3D reconstruction based on animal statistical shape models, we implement the construction and learning of the statistical shape model of real cattle. Given the establishment of the statistical shape model of cattle, a 3D reconstruction and body measurement approach of real cattle based on low-quality point cloud data is proposed. Nine indicators are calculated and the overall estimation MAPE (Mean Absolute Percentage Error) is 10.27%. The whole process of the body measurement algorithm proposed in our paper can be extended to other quadrupeds.

Need for a new test method for determining the acoustic performance of road traffic noise reducing devices

Noise reducing devices such as sound barrier walls are common ways to mitigate traffic noise problems in residential areas next to arterial roads or railways. The basic performance of noise reducing devices is sound insulation and absorption. However, the existing measurement methods are not adequate for characterizing sound insulation and absorption performances of noise reducing devices. The sound insulation measurement method is different from the actual installation condition of the noise reducing devices that transmit the sound to the free field, and the sound absorption coefficient measurement method does not include the transmitted sound energy. This study raised the problem of the current acoustic performance measurement method of noise-reducing devices and arises the need for a new measurement method to complement it.

Efficient and precise docking trajectory optimization for the ship block assembly

The assembly of the ship block is an extremely important stage of the shipbuilding process. Nevertheless, currently, the manual assembly efficiency is low, the accuracy is poor, and collision is very easy to occur. Therefore, there is an urgent need to conduct technical research on the automatic docking of ship blocks. The core of the automated docking technology is the attitude estimation and the trajectory planning of the posturing equipment. However, current data measurement and point set matching methods lead to large attitude-estimation errors, and it is difficult to meet the accuracy requirements of the assembly. Moreover, the current ship block trajectory planning methods pay more attention to single metrics, for example, time or energy consumption, while omitting the shock degree. In response to the above, this study first proposes a high-precision matching method for measuring point sets, in order to estimate the exact attitude of the ship block. Subsequently, trajectory translation for the block is performed using the seventh-degree polynomial. On this basis, a nonlinear weighted improved particle swarm optimization (IPSO) method is proposed to optimize the time, energy consumption and shock degree in the ship block trajectory planning process. Finally, the accuracy of the matching optimization is validated by simulation analysis and it is concluded that the seventh-degree polynomial leads to less shock than other polynomials. Furthermore, the shock force does not change abruptly even when the ship block is poised in steps. Through IPSO, the energy consumption and shock degree performance indices are optimized by 37.07% and 50.06%, respectively, in the ship block translation process.

Improving transportation project evaluation by recognizing the role of spatial scale and context in measuring non-user economic benefits

The usefulness of transportation project evaluation depends on the completeness of its benefit measures. Since transportation networks are intrinsically spatial, transportation improvement projects have spatial access and location characteristics that can lead to a variety of non-user economic benefits. Recent research has enabled us to better understand how spatial context and spatial heterogeneity play further roles in generating efficiency gains for non-users, in the form of productivity, income, and cost savings for both private and public sectors of the economy. This paper draws upon that body of research to expand our understanding of the means by which transportation projects can generate economic efficiency gains, and approaches needed to measure them. It covers topics beyond those captured by current definitions of “wider economic benefits,” including additional sources of scale economies associated with freight distribution and connectivity, and further public and private sector economic gains enabled by environmental and social inclusion improvement. It points to ways that non-user economic benefits can be more comprehensively defined and better measured by recognizing their spatial scale, context, and threshold effects. It also identifies ways that current benefit measurement methods introduce unintended bias into transportation investment decision-making through omission and mismeasurement. The result is a case for a refresh of thinking about how we classify and recognize non-user economic benefits in transportation evaluation, and how we apply transportation planning and economic models to support their measurement.

Static Characteristics of Magnetic Modulation DC Converters with Analog Filter

The paper examines the most important requirements for current converters, the features of magnetic modulation converters, and identifies their fundamental and design features. The paper considers the principle of constructing converters for contactless DC measurement and their disadvantages of converters, methods of current measurement using magnetic modulation current converters, in which the magnetic permeability of a core made of ferromagnetic material is modulated. The influence of the parameters of the elements of a magnetic modulation current converter with an analog filter on their static characteristics and the influence of modulation on the static characteristics of the sensor have been determined. It has been revealed that the discrete operation of the magneto-modulation DC converter does not affect its static characteristics and the nonlinearity due to the type of modulation also does not affect the static characteristics of the sensor. The most important requirement for the operation of a magneto-modulation DC converter for autonomous power supplies with recharging buffer batteries is the formation of a static characteristic with the specified properties: linearity, sensitivity and the required range of operating currents. An analytical expression for the static characteristic is obtained in the form of the dependence of the output voltage on the values of T1 and T2 for the basic version of a magnetic modulation DC converter with an analog low-pass filter. Curves of the static characteristics of the magneto-modulation DC converter have been constructed for different values of the resistance of the ballast resistor R, as well as curves of the static characteristics of the magneto-modulation DC converter for different values of the supply voltage E. Analytical expressions for the static characteristics of a magneto-modulation DC converter based on magnetic transistor multivibrators with pulse-width modulation, curves of their characteristics and the output voltage of a magnetic modulation DC converter with a digital output and a discrete filter have been obtained.

Appraisal of the Accuracy and Reliability of Cone-Beam Computed Tomography and Three-Dimensional Printing for Volumetric Mandibular Condyle Measurements of a Human Condyle.

Background This study aims to evaluate the accuracy of volumetric measurements of three-dimensional (3D)-printed human condyles from cone-beam computed tomography (CBCT) in comparison to physical condyles using a water displacement test. Methodology A sample of 22 dry condyles was separated from the mandibular body by disc, mounted on a base made of casting wax, and scanned using the SCANORA (Scanora 3DX, Soredex, Finland) CBCT scanner. Subsequently, the projection data were reconstructed with the machine-dedicated OnDemand 3D (Cybermed Co., Seoul, Korea). The Standard Tessellation Language file was prepared for 3D printing using chitubox slicing software v1.9.1. Frozen water-washable gray resin was used for 3D printing. All condyles were printed using the same parameters and the same resin. The volumetric measurements were then performed using a customized modified pycnometer based on water volume and weight displacement. Volumetric measures were performed for both the physical human condyles and the 3D-printed replicas and the measurements were then compared. Results The volume of dry condyles using the water displacement method showed an average (±SD) of 1.925 ± 0.40 cm3. However, the volume of 3D-printed replicas using the water displacement method showed an average (±SD) of 2.109 ± 0.40 cm3. The differences in measurements were insignificant (p > 0.05), as revealed by an independent t-test. Conclusions Highly precise, accurate, and reliable CBCT for volumetric mandibular condyle was applied for measurements of a human condyle and 3D-printed replica. The modified pycnometer for volumetric measurements presented an excellent volumetric measure based on a simple water displacement device. The tested modified pycnometer can be applied in volumetric measurements in both 3D-printed and mandibular condyle.For best accuracy, the highest scanning resolution possible should be used.As it directly handles irregularly shaped solid objects in a non-destructive manner with a high level of precision and reliability, this 3D scanning approach may be seen as a superior alternative to the current measurement methods.

Sound absorption coefficient measurement for various building elements

The current sound absorption coefficient testing measurement method, ISO 354, primarily focuses on materials used for surface coverings or equivalent sound absorption objects. However, there are other building elements such as lightweight partition walls and windows that do not have solid structures behind them. These elements may allow sound to transmit to adjacent interior spaces or escape to the outside. On the other hand, the transmitted sound is expected to be rebounded into the measurement room when the test material is placed on a hard and thick surface as described in ISO 354. The test was conducted in a reverberation chamber located at the center of three consecutive acoustic testing chambers: reverberation-reverberation-anechoic. The testing chambers are equipped with test openings between them and are fully isolated from one another. The purpose of the test was to confirm whether the current measurement method reflects the influence of the assumed rebounded sound. The sound absorption coefficients were measured with the specimen installed on the floor, representing the ISO 354 condition, and comparisons were made to the conditions where the specimen was installed in another reverberation chamber opening and in the anechoic chamber opening.

Technique for the comprehensive characterization of supraharmonic disturbances (9–150 kHz) in the joint time-frequency domain

The inverter-based devices connected to the low-voltage (LV) grid, such as photovoltaic panels (PVs) and electric vehicle charging stations (EVCSs), are known to generate supraharmonic distortions in CISPR Band A (9–150 kHz) that may interfere power line communications (PLC). Current measurement methods were designed to provide results of the disturbances only in the frequency domain. Thus, impulsive signals and fast amplitude variations of the disturbances are lost in the calculation process. This work addresses this issue by developing a statistical study of the distribution of supraharmonic disturbances in the joint time-frequency domain, which allows the clear differentiation of impulsive signals. The results show that the amplitudes of the normalized measurements can be modeled by the t Location-Scale probability density function (PDF), which can be used to set a threshold for the differentiation of the impulsive disturbances. The study proposes a measurement method and a set of metrics for the complete characterization of the disturbances present in the LV grid, by characterizing the noise and distortions as a whole and also impulsive emissions separately. The main contribution of this work is that the measurement technique characterizes the disturbances in the joint time-frequency domain, and it is coherent with methods below 9 kHz. The proposed method is applied to some typical grid recordings containing different types of noise and emissions. The results demonstrate that the method allows the complete characterization of the supraharmonic distortions present in the LV grid and a proper differentiation of the impulsive emissions in the joint time-frequency domain.