Current Measurement Methods Research Articles

Diagnostic Criteria for Breast Cancer-Related Lymphedema of the Upper Extremity: The Need for Universal Agreement.

With advances in breast cancer treatments and resultant increased survival rates, emphasis has been placed on post-treatment complications such as breast cancer-related lymphedema (BCRL), a chronic, negative sequela of breast cancer treatment. Accurate BCRL diagnosis necessitates longitudinal screening beginning at preoperative baseline. Prospective screening programs incorporating symptoms, objective measurements and clinical examination allow for early detection, early intervention, and improved BCRL prognosis. Currently, varied diagnostic criteria for BCRL exist, and this lack of consensus leads to variation in diagnostic and screening practices across institutions. This review outlines current diagnostic tools, including subjective and objective measurement methods and clinical examination. The merits of different criteria are evaluated and recommendations are made regarding measurement tools and diagnostic criteria for BCRL. Ultimately, the BCRL diagnostic process should be universalized and combine objective measurements, clinical evaluation, and symptoms assessment, and adhere to the best practices of the measurement tools used.

A novel use of biomechanical model-based deformable image registration (DIR) for assessing colorectal liver metastases ablation outcomes.

Purpose:Colorectal cancer is the third most common form of cancer in the United States, and up to 60% of these patients develop liver metastasis. While hepatic resection is the curative treatment of choice, only 20% of patients are candidates at the time of diagnosis. While percutaneous thermal ablation (PTA) has demonstrated 24%–51% overall 5-year survival rates, assurance of sufficient ablation margin delivery (5 mm) can be challenging, with current methods of 2D distance measurement not ensuring 3D minimum margin. We hypothesized that biomechanical model-based deformable image registration (DIR) can reduce spatial uncertainties and differentiate local tumor progression (LTP) patients from LTP-free patients.Methods:We retrospectively acquired 30 patients (16 LTP and 14 LTP-free) at our institution who had undergone PTA and had a contrast-enhanced pre-treatment and post-ablation CT scan. Liver, disease, and ablation zone were manually segmented. Biomechanical model-based DIR between the pre-treatment and post-ablation CT mapped the gross tumor volume onto the ablation zone and measured 3D minimum delivered margin (MDM). An in-house cone-tracing algorithm determined if progression qualitatively collocated with insufficient 5 mm margin achieved.Results:Mann–Whitney U test showed a significant difference (p < 0.01) in MDM from the LTP and LTP-free groups. A total of 93% (13/14) of patients with LTP had a correlation between progression and missing 5 mm of margin volume.Conclusions:Biomechanical DIR is able to reduce spatial uncertainty and allow measurement of delivered 3D MDM. This minimum margin can help ensure sufficient ablation delivery, and our workflow can provide valuable information in a clinically useful timeframe.

Deciphering the Interaction between Neonatal Fc Receptor and Antibodies Using a Homogeneous Bioluminescent Immunoassay.

Long half-life of therapeutic Abs and Fc fusion proteins is crucial to their efficacy and is, in part, regulated by their interaction with neonatal Fc receptor (FcRn). However, the current methods (e.g., surface plasmon resonance and biolayer interferometry) for measurement of interaction between IgG and FcRn (IgG/FcRn) require either FcRn or IgG to be immobilized on the surface, which is known to introduce experimental artifacts and have led to conflicting data. To study IgG/FcRn interactions in solution, without a need for surface immobilization, we developed a novel (to our knowledge), solution-based homogeneous binding immunoassay based on NanoBiT luminescent protein complementation technology. We optimized the assay (NanoBiT FcRn assay) for human FcRn, mouse FcRn, rat FcRn, and cynomolgus FcRn and used them to determine the binding affinities of a panel of eight Abs. Assays could successfully capture the modulation in IgG/FcRn binding based on changes in Fc fragment of the Abs. We also looked at the individual contribution of Fc and F(ab)2 on the IgG/FcRn interaction and found that Fc is the main driver for the interaction at pH 6. Our work highlights the importance of using orthogonal methods to validate affinity data generated using biosensor platforms. Moreover, the simple add-and-read format of the NanoBiT FcRn assay is amenable for high-throughput screening during early Ab discovery phase.

Automatic Sensing and Measuring Technique for Power Metering

The growing demand for electricity has set higher requirements for the sensing and measurement system of smart distribution network. Therefore, a new state monitoring technology for power metering is proposed based on automatic sensing and measuring technique to improve power metering. Firstly, the influence of various physical conditions and natural environment is analyzed on power metering equipment. Then, internal detection is used to detect the operation state of the equipment. Secondly, DC (direct current) magnetic bias is detected by self-excited fluxgate. Furthermore, the working condition of the secondary circuit is tested by the secondary circuit current measurement method. Finally, the narrowband Internet of Things technology is adopted to conduct data communication with the terminal platform. The research results show that compared with the traditional online operation state detection and management system of smart distribution network, the innovative state monitoring technology can additionally monitor the temperature, DC magnetic bias and secondary circuit of the distribution network. This shows that improved monitoring technology based on automatic sensing and measuring technique can monitor the important state of the distribution network to reduce the risks caused by the inability to detect potential problems and improve the performance of the distribution network. The optimized state metering technology makes an example for the improvement of automatic sensing and measuring technique of the metering equipment of smart distribution network nationwide.

Measurement of Pharyngeal Air Pressure During Phonation Using High-Resolution Manometry.

Purpose The study of air pressure in the vocal tract is essential to understanding vocal function. Changes in vocal tract shape during different phonatory gestures are hypothesized to produce nonuniform air pressure across lower vocal tract locations. Current methods of air pressure measurement, however, are limited to a single location in the anterior oral cavity. The purposes of this study were (a) to assess the feasibility of a novel method of simultaneously measuring phonatory air pressure at multiple locations across the lower vocal tract using high-resolution pharyngeal manometry (HRM) and (b) to compare pressure across locations and among phonatory tasks. Method Two subjects underwent HRM while performing phonatory tasks. A catheter was passed transnasally and air pressure was measured simultaneously at five locations between the velopharyngeal port and the upper esophageal sphincter. Descriptive statistics were calculated for each location by task, and for each task averaged across locations. Results HRM was well tolerated, and air pressures from multiple locations in the lower vocal tract were able to be obtained simultaneously. During vocal tract semi-occlusion tasks, air pressures differed by location. Pressures averaged across locations demonstrated a pattern of increasing pressure with increasing semi-occlusion. Conclusions HRM is feasible for measuring air pressure simultaneously at multiple locations in the lower vocal tract during phonation with high spatial and temporal resolution, providing rich data to augment understanding of vocal function. The high spatial and temporal resolution yielded by this new method, paired with preliminary evidence that pressures change by location as a function of phonatory task, may be useful in future assays exploring differences in lower vocal tract air pressures between normal and disordered populations.

Deep Learning Convolutional Neural Network Applying for the Arctic Acoustic Tomography Current Inversion Accuracy Improvement

Warm current has a strong impact on the melting of sea ice, so clarifying the current features plays a very important role in the Arctic sea ice coverage forecasting study field. Currently, Arctic acoustic tomography is the only feasible method for the large-range current measurement under the Arctic sea ice. Furthermore, affected by the high latitudes Coriolis force, small-scale variability greatly affects the accuracy of Arctic acoustic tomography. However, small-scale variability could not be measured by empirical parameters and resolved by Regularized Least Squares (RLS) in the inverse problem of Arctic acoustic tomography. In this paper, the convolutional neural network (CNN) is proposed to enhance the prediction accuracy in the Arctic, and especially, Gaussian noise is added to reflect the disturbance of the Arctic environment. First, we use the finite element method to build the background ocean model. Then, the deep learning CNN method constructs the non-linear mapping relationship between the acoustic data and the corresponding flow velocity. Finally, the simulation result shows that the deep learning convolutional neural network method being applied to Arctic acoustic tomography could achieve 45.87% accurate improvement than the common RLS method in the current inversion.

A pluggable current collector for in-operando current measurements in all-vanadium redox flow batteries with flow field

Understanding current distribution in operating Vanadium redox flow batteries (VRFBs) is vital for improving battery design and performance as the non-uniform current density distribution is known as a major cause of the corrosion and side reactions in VRFBs. However, the existing method for current density measurement in the VRFB with flow field is complex and the rib conductive structure of graphite plate is changed which reduces the measurement accuracy and reliability. In this study, we propose a novel pluggable current collector for in-operando current distribution measurements which greatly simplifies the current density distribution measurement process in VRFBs with flow field. The new method relies on eight pluggable graphite units in a flow plate frame to replicate the actual serpentine flow field structure, thereby providing higher measurement reliability compared to the existing methods which are mostly invasive. Using the new method, current density distributions at different electrode compression ratios (CR) and inflow electrolyte rates are investigated. It is found that insufficient supplemental reactant in electrode border region is the main reason for the uneven current density distribution and the current density non-uniformity is intensified in the initial and final stages of cycling process. Increasing CR can improve the current density in the electrode core region. The overall current density uniformity in a VRFB with serpentine flow field can be enhanced by increasing the inflow electrolyte rate. The developed method is believed to facilitate the understanding of the coupled local reactions and transport processes and guide on the future design of VRFBs.

Diagnostics of PID Early Stage in PV Systems

Potential induced degradation (PID) is a serious threat for the photovoltaic (PV) industry. The risk of PID may increase with increasing operating voltage of PV systems. Although PID tests are currently standard tests, the expansion of floating PV power plants and installation in humid climates show that PID-free modules are still sensitive to this type of degradation. Therefore, a method that can detect PID in the initial phase before standard tests reveal it, is necessary to increase the reliability of PV systems and maintain their lifetime. One possible tool for revealing early-stage PID manifestations is impedance spectroscopy and I-V dark curves measurements. Both IS and dark current measurement methods are sensitive to cell shunt resistance (RSH), which is strongly influenced by PID before significant power loss and can act as an early stage PID detection mechanism. The paper describes the differences of the common P-type PV module parameters both during the degradation process and also during the regeneration process when diagnosed by conventional and IS and dark current measurement methods.

Ångström exponent errors prevent accurate visibility measurement

Abstract. Visibility is an indicator of atmospheric transparency, and it is widely used in many research fields, including air pollution, climate change, ground transportation, and aviation. Although efforts have been made to improve the performance of visibility meters, a significant error exists in measured visibility data. This study conducts a well-designed simulation calibration of visibility meters, which proves that current methods of visibility measurement include a false assumption, leading to the long-term neglect of an important source of visibility error caused by erroneous values of Ångström exponents. This error has two characteristics, namely (1) independence, which means that the magnitude of the error is independent of the performance of the visibility meter. It is impossible to reduce this error by improving the performance of visibility meters. The second characteristic is (2) uncertainty, which means the magnitude of the error does not show a clear change pattern but can be substantially larger than the measurement error of visibility meters. It is impossible to accurately estimate the magnitude of this error or its influence on visibility measurements. Our simulations indicate that, as errors in visibility caused by erroneous values of Ångström exponents are inevitable using current methods of visibility measurement, reliable visibility data cannot be obtained without major adjustments to current measurement methods.

Digital Optical CT Application to HVDC Earthing Line Fault Measurements

A digital optical current transducer designed for the measurement of small alternating currents is applied to current measurements for an HVDC earthing line. A novel scanning band pass filter was used to make experimental measurements of small high frequency currents. Currents from 1 kHz to 5 kHz and 0.2 A to 2 A in the presence of 20 A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> have been experimentally made. With accuracies of less than 0.4% for the 2 A measurement. The optical current transducers can measure currents remotely up to 20 km from the converter station. This new optical current sensor measurement method can allow the location of faults on HVDC earthing lines.

Guide to controlling the electron dose to improve low-dose imaging of sensitive samples

This work describes the methods of beam current measurement and proposes the construction of an easily fabricated Faraday cup for use in any side-entry transmission electron microscope. Moreover, a method of calculating the dose of electrons with the use of a digital camera is proposed and verified with the use of two slightly different microscope setups. The method turned out to be particularly useful for estimating the smallest doses of electrons used in the imaging of particularly sensitive samples.

Cerebrovascular Reactivity Mapping Using Resting-State BOLD Functional MRI in Healthy Adults and Patients with Moyamoya Disease.

Background Cerebrovascular reserve, the potential capacity of brain tissue to receive more blood flow when needed, is a desirable marker in evaluating ischemic risk. However, current measurement methods require acetazolamide injection or hypercapnia challenge, prompting a clinical need for resting-state (RS) blood oxygen level-dependent (BOLD) functional MRI data to measure cerebrovascular reactivity (CVR). Purpose To optimize and evaluate an RS CVR MRI technique and demonstrate its relationship to neurosurgical treatment. Materials and Methods In this HIPAA-compliant study, RS BOLD functional MRI data collected in 170 healthy controls between December 2008 and September 2010 were retrospectively evaluated to identify the optimal frequency range of temporal filtering on the basis of spatial correlation with the reference standard CVR map obtained with CO2 inhalation. Next, the optimized RS method was applied in a new, prospective cohort of 50 participants with Moyamoya disease who underwent imaging between June 2014 and August 2019. Finally, CVR values were compared between brain hemispheres with and brain hemispheres without revascularization surgery by using Mann-Whitney U test. Results A total of 170 healthy controls (mean age ± standard deviation, 51 years ± 20; 105 women) and 100 brain hemispheres of 50 participants with Moyamoya disease (mean age, 41 years ± 12; 43 women) were evaluated. RS CVR maps based on a temporal filtering frequency of [0, 0.1164 Hz] yielded the highest spatial correlation (r = 0.74) with the CO2 inhalation CVR results. In patients with Moyamoya disease, 77 middle cerebral arteries (MCAs) had stenosis. RS CVR in the MCA territory was lower in the group that did not undergo surgery (n = 30) than in the group that underwent surgery (n = 47) (mean, 0.407 relative units [ru] ± 0.208 vs 0.532 ru ± 0.182, respectively; P = .006), which is corroborated with the CO2 inhalation CVR data (mean, 0.242 ru ± 0.273 vs 0.437 ru ± 0.200; P = .003). Conclusion Cerebrovascular reactivity mapping performed by using resting-state blood oxygen level-dependent functional MRI provided a task-free method to measure cerebrovascular reserve and depicted treatment effect of revascularization surgery in patients with Moyamoya disease comparable to that with the reference standard of CO2 inhalation MRI. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Wolf and Ware in this issue.

The Signal Injection Method with High-Frequency for Distribution Network Capacitive Current Measurement

In order to solve the problem of limited frequency selection range and simplify calculations on the grounded capacitance measurement for the ungrounded distribution system, a high-frequency injecting method for the capacitive current measurement is proposed in the paper. The injecting frequency can be high enough to ignore capacitive reactance and leakage resistance comparing with leakage inductance. The leakage inductance value is obtained directly on the base of simplified calculation. Then the resonant frequency of the power system needs to be obtained by the traditional resonant method. Finally, the grounded capacitance can be calculated through the equivalent circuit and the simultaneous equations. The simulation and experiments verify the feasibility of the high-frequency method. The experiment results prove that this method not only solves the problem of frequency selection, but also has advantages of convenience and high precision (the relative error is less than 5%), which is also suitable for the larger grounded capacitance system.

Precise measurement of the electron beam current in a TEM

Modern quantitative TEM methods such as the ζ-factor technique require precise knowledge of the electron beam current. To this end, a macroscopic Faraday cup was designed and constructed. It can replace the viewing screen in the projection chamber of a TEM and guarantees highly accurate measurement of the electron beam with precision only limited by the used amperemeter. The easy to install, affordable device is shown to be highly apt for precision measurement of currents >5pA. The Faraday cup results are used for an assessment and a comparison of various other beam current measurement methods. It is found that the built-in screen amperemeter of the used TEM is quite inaccurate and that measurements using the screen in general tend to underestimate the current. If present, the drift tube of a spectrometer can also be used as a Faraday cup, but certain described peculiarities have to be taken into account. Direct ultrafast electron detection cameras allow precise measurement at very small currents. For the electron counting technique, which exploits single electron detection capabilities of STEM detectors, a systematic current underestimation was observed and investigated. This results in a reformulated routine for the method and with these improvements it is demonstrated to be capable of accurate high-precision measurements for currents <5pA.

Analysis and design of a self-oscillating quasi-digital fluxgate current sensor for DC current measurement.

In this paper, an open-loop self-oscillating fluxgate-based current measurement method is presented. The proposed sensor does not require the low-pass filter necessary in traditional measurement technologies and does not require an analog-to-digital converter when connected to digital systems. More importantly, although the proposed measurement method is based on the open-loop configuration, its measurement accuracy is close to that of the traditional self-oscillating fluxgate measurement technology based on the closed-loop configuration. Accurate mathematical models are established to describe the basic characteristics of the measurement method, and design criteria of the sensor are proposed. The test results show that the proposed measurement method has good linearity; for example, in the full scale of 100A, its linearity is about 0.4% and can be improved to below 0.2% when the first-order polynomial fitting method is used.

A New Method for Static Measurement of Two Axles Vehicle Centroid Height

Background: Vehicle centroid height is an important parameter in vehicle control systems. It plays an important role in vehicle roll stability and handling stability. At present, there are mainly static and dynamic measurement methods such as swing method, mass reaction method, marking method and so on. These static measurement methods often require a fixed suspension to make the measurement process time-consuming and laborious, and measurement errors will occur when the suspension is not fixed firmly, and it is impossible to measure the mass center position of spring-loaded mass and non-spring-loaded mass. Objective: Therefore, it is of great practical significance to study a high accuracy, low cost and fast measurement method of vehicle centroid height. We revised and summarized all patents relating to methods for estimating vehicle centroid height. And a new method of centroid measurement is designed in this paper. Methods: According to the change of tire flattening radius and suspension, the change of spring and non-spring mass center height when vehicle axle load changes, the method of delineation is used to calculate the change of tire flattening radius and suspension; According to the relationship between vehicle tilt angle and front and rear axle load, the principle of moment balance and the principle of mass balance, it determines the geometric relationship between the variables, and to take the moment of the contact point between the front wheel and the ground, the moment balance equation is established, and the height of the vehicle mass center, spring load and non-spring load mass center in the horizontal position of the vehicle are obtained. Results: This measurement method is different from the existing static measurement of vehicle centroid height, it does not need the fixed suspension, only need to measure several dimensions, we can avoid heavy labor and safety accidents brought by the fixed suspension, it can also reduce the measurement error caused by fixation, but also can draw the centroid location of the sprung mass and unsprung mass. The measurement method is simple, economical and accurate, and is widely applicable on two-axle vehicles. Conclusion: The purpose of this paper is to provide a static and accurate measurement method of vehicle centroid height, so as to solve the problem that the current static measurement method of vehicle centroid height needs fixed suspension, and measurement errors will occur when the suspension is not fixed properly, so it is impossible to measure the centroid position of spring-loaded mass and non-spring-loaded mass.

Phase Imbalance Analysis of GF-3 Along-Track InSAR Data for Ocean Current Measurement

There are two useful methods of current measurement based on synthetic aperture radar (SAR): one is along-track interferometry (ATI), and the other is Doppler centroid analysis (DCA). For the ATI method, the interferometric phase must be accurate enough for ocean current measurements. Therefore, the space-varying of phase imbalances along the range, caused by antenna phase center position error, attitude error, antenna electronic miss pointing, antenna pattern mismatch, and other reasons, cannot be ignored. Firstly, this paper mainly analyzes the above possible factors by using real GF-3 ATI data and error model simulation results. Secondly, the ocean current has been preliminarily measured by the ATI method and the DCA method, using CDOP model, based on the GF-3 ATI data of the ocean scene near Qingdao, China, which is up to around −1.45 m/s. The results of the two methods are in good agreement with the correlation coefficient of 0.98, the mean difference of −0.010 m/s, and the root mean squared error (RMSE) of 0.062 m/s. Moreover, by comparing with the current measured by high-frequency surface wave radar (HFSWR), the correctness of the analysis is further proved.

Heart rate estimation based on face video under unstable illumination

Remote photoplethysmography (rPPG) is a noncontact heart rate (HR) measurement technique. The current heart rate measurement methods based on rPPG all require ideal lighting conditions, but the lighting in real scenes is complicated, Therefore, this article proposes a robust heart rate measurement method when unstable light (time-varying light and uneven spatial illumination) exists. First, the method locates the ROI(Region of Interest) area of ​​the face, divides it into blocks, and uses the color signals of different sub-blocks to establish a three-dimensional rPPG model. Second, the method performs logarithmic operations on each frame of the image to convert the relationship between the illumination component and the reflection component from a product to a sum so that the reflected component and noise can be separated in the frequency domain. Then, the ensemble empirical mode decomposition (EEMD) is used to decompose the reflected component, and the obtained intrinsic mode function (IMF) is applied to obtain the waveform reflecting the change in the heart rate. Finally, the signal quality (SQ) of each ROI sub-block is calculated, and the high-quality signals are combined to reconstruct the heart rate signal.

A simulation and experiment coassisted learning platform for understanding electromagnetic interaction in a smart grid

AbstractAn innovative current measurement method in power systems has attracted more attention from both the industry and academia. Nevertheless, students can feel challenged when assigned to learn new concepts with the currently already difficult engineering courses. Therefore, in this paper, a training platform is designed based on finite element analysis simulation and laboratory experiments. With this training platform, simple and effective simulations and experiments can be performed. In addition, extended applications of this training platform are presented such as design of the magnetic shielding structure, magnetic flux density visualization and calculation of overhead power lines. This design can help engineering students to better understand the application of electromagnetics and the novel current measurement research field.

Simulation and Design of DC Sensor Based on Tunnel Magnetoresistance

In order to measure the DC current measurement, a method of current measurement and interference error elimination based on tunnel magnetoresistance (TMR) DC sensor is established. Firstly, the basic principle of TMR sensor is described, and its open-loop transfer function is derived, and the parameter variables related to its open-loop gain are analyzed; an adaptive filtering algorithm based on least mean squares (LMS) is proposed to detect the magnetic induction intensity. Taking three magnetic sensors as an example, the magnetic field estimation value under this condition is calculated. Finally, the correctness and effectiveness of the design method are verified by simulation.