Unconventional Measurement Research Articles

Multipoint surface electromyography measurement using bull’s-eye electrodes for wide-area topographic analysis

BackgroundSurface electromyography (sEMG) is primarily used to analyze individual and neighboring muscle activity. However, using a broader approach can enable simultaneous measurement of multiple muscles, which is essential for understanding muscular coordination. Using the “bull’s-eye electrode,” which allows bipolar derivation without directional dependence, enables wide-area multipoint sEMG measurements. This study aims to establish a multipoint measurement system and demonstrate its effectiveness and evaluates forearm fatigue and created topographic maps during a grasping task.MethodsNine healthy adults with no recent arm injuries or illnesses participated in this study. They performed grasping tasks using their dominant hand, while bull’s-eye electrodes recorded their muscle activity. To validate the effectiveness of the system, we calculated the root mean squares of muscle activity and entropy, an indicator of muscle activity distribution, and compared them over time.ResultsThe entropy analysis demonstrated a significant time-course effect with increased entropy over time, suggesting increased forearm muscle uniformity, which is possibly indicative of fatigue. Topographic maps visually displayed muscle activity, revealing notable intersubject variations.DiscussionBull’s-eye electrodes facilitated the capture of nine homogeneous muscle activity points, enabling the creation of topographic images. The entropy increased progressively, suggesting an adaptive muscle coordination response to fatigue. Despite some limitations, such as inadequate measurement of the forearm muscles’ belly, the system is an unconventional measurement method.ConclusionThis study established a robust system for wide-area multipoint sEMG measurements using a bull’s-eye electrode setup. This system effectively evaluates muscle fatigue and provides a comprehensive topographic view of muscle activity. These results mark a significant step towards developing a future multichannel sEMG system with enhanced measurement points and improved wearability.Trial registrationThis study was approved by the Ethics Committee of Chiba University Graduate School of Engineering (acceptance number: R4-12, Acceptance date: November 04, 2022).

Acoustic Prediction of a Multilateral-Well Unconventional Reservoir Based on a Hybrid Feature-Enhancement Long Short-Term Memory Neural Network

Due to the complexity of unconventional reservoir measurement, log data acquired are often incomplete, which results in inaccurate formation evaluation and higher operational risks. Common solutions, such as coring, are typically high cost related while not being sufficiently representative. In recent years, neural network has received increasing attention given its strong ability in data prediction. Nevertheless, most neural networks only focus on one specific feature of the selected data, thus prohibiting their prediction accuracy for reservoir logs where data are often dominated by more than one key feature. To address this challenge, a novel multi-channel hybrid Long Short-Term Memory (LSTM) neural network for effective acoustic log prediction is proposed. The network combines Convolutional Neural Network (CNN) and LSTM, where CNN is used to extract spatial features of the logs and LSTM network extracts temporal features with the assistance of an adaptive attention mechanism implemented for key feature recognition. In addition, the strong heterogeneity of unconventional reservoirs also increases the difficulty of prediction. Therefore, according to the characteristics of the unconventional reservoir, we designed three feature enhancement methods to mine the hidden information of logs. To prove the performance of the proposed network, a case study is presented with data acquired from Jimusar Oilfield, one of the largest unconventional reservoirs in China. Four groups of experiments are conducted, and the proposed network is employed for acoustic log prediction. The predicted results are validated against measurement (R2: 92.27%, 91.42%, 93.31%, and 92.03%; RMSE: 3.32%, 3.92%, 3.06%, and 3.53%). The performance of the proposed network is compared to other networks such as CNN, LSTM, CNN-LSTM, and random forest (RF). The comparisons show that the proposed network has the highest accuracy level of prediction, which means it provides an effective approach to complement missing data during complicated unconventional reservoir measurement and, therefore, could be of significant potential in energy exploration.

Fundamental limits and optimal estimation of the resonance frequency of a linear harmonic oscillator

All physical oscillators are subject to thermodynamic and quantum perturbations, fundamentally limiting measurement of their resonance frequency. Analyses assuming specific ways of estimating frequency can underestimate the available precision and overlook unconventional measurement regimes. Here we derive a general, estimation-method-independent Cramer Rao lower bound for a linear harmonic oscillator resonance frequency measurement uncertainty, seamlessly accounting for the quantum, thermodynamic and instrumental limitations, including Fisher information from quantum backaction- and thermodynamically driven fluctuations. We provide a universal and practical maximum-likelihood frequency estimator reaching the predicted limits in all regimes, and experimentally validate it on a thermodynamically limited nanomechanical oscillator. Low relative frequency uncertainty is obtained for both very high bandwidth measurements (≈10−5 for τ = 30 μs) and measurements using thermal fluctuations alone (<10−6). Beyond nanomechanics, these results advance frequency-based metrology across physical domains.

Existence of two spin dynamics in the temperature and magnetic field dependence of the magnetization curves of ferrimagnetic Co1.75Fe1.25O4 and its composite with BaTiO3

The present work describes ferrimagnetic properties of spinel oxide Co1.75Fe1.25O4 (CFO) and its composite (CFO_BTO) with ferroelectric and non-magnetic BaTiO3 (BTO). Rietveld refinement of the synchrotron X-ray diffraction patterns provided detailed structural phase information of the CFO and CFO_BTO samples. The dc magnetization measurements confirmed blocking temperature of the samples around 300 K for applied magnetic field 500 Oe and exchange bias effect at 5 K. On the other hand, both the samples exhibited a strong magnetic memory effect at around 250 K and the memory effect gradually suppressed at low temperatures. Apart from conventional modifications of magnetic moment and coercivity in composite system with reference to pure spinel ferrite system, the present work has shown that ferrimagnetic parameters can be varied by adopting some unconventional measurement protocols, where time dependent magnetization has been recorded during measurements of the temperature and field dependent magnetization curves. The analysis of waiting time dependent magnetization data confirmed the existence of two non-equilibrium spin dynamics, defined by different time constants, both in CFO ferrite and CFO_BTO composite systems. The measurements also confirmed the dilution of magnetic exchange interaction and faster spin relaxation in the composite system.

Detector Tilt Considerations in Bragg Coherent Diffraction Imaging: A Simulation Study

This paper addresses the three-dimensional signal distortion and image reconstruction issues in X-ray Bragg coherent diffraction imaging (BCDI) in the event of a general non-orthogonal orientation of the area detector with respect to the diffracted beam. Growing interest in novel BCDI adaptations at fourth-generation synchrotron light sources has necessitated improvisations in the experimental configuration and the subsequent data analysis. One such possibly unavoidable improvisation that is envisioned in this paper is a photon-counting area detector whose face is tilted away from the perpendicular to the Bragg-diffracted beam during the acquisition of the coherent diffraction signal. We describe a likely circumstance in which one would require such a detector configuration, along with the experimental precedent at third-generation synchrotrons. Using physically accurate diffraction simulations from synthetic scatterers in the presence of such tilted detectors, we analyze the general nature of the observed signal distortion qualitatively and quantitatively and provide a prescription to correct for it during image reconstruction. Our simulations and reconstructions are based on an adaptation of the known theory of BCDI sampling geometry, as well as the recently developed projection-based methods of wavefield propagation. Such configurational modifications and their numerical remedies are potentially valuable in realizing unconventional coherent diffraction measurement geometries, eventually paving the way for the integration of BCDI into new material characterization experiments at next-generation light sources.

Piston secondary motion measurement by laser displacement sensors

Measurement of the piston group behavior is still a challenge. Achieved accuracy and complexity go hand in hand with the financial requirements. This paper presents an unconventional measurement of the piston secondary motion using laser displacement sensors. Two sensors help capture the piston tilt angle, while the third sensor is used for the piston lateral motion measurement. These sensors are aimed at the piston crown. The passage between the laser source and the target spot has to be transparent. Therefore, side-valve internal combustion engine is employed. It enables the cylinder head to be made of the transparent material such as cast plexiglass. In the initial stage, the experimental engine is motored during the measurement. As for the measurement of the piston tilt angle, the results are within the physical limits. However, the same does not apply for the piston lateral results, where the measured values are too high, so the piston would penetrate the liner.

A practical approach to tramway track condition monitoring: vertical track defects detection and identification using time-frequency processing technique

Abstract This paper presents an automatic method for detecting vertical track irregularities on tramway operation using acceleration measurements on trams. For monitoring of tramway tracks, an unconventional measurement setup is developed, which records the data of 3-axes wireless accelerometers mounted on wheel discs. Accelerations are processed to obtain the vertical track irregularities to determine whether the track needs to be repaired. The automatic detection algorithm is based on time–frequency distribution analysis and determines the defect locations. Admissible limits (thresholds) are given for detecting moderate and severe defects using statistical analysis. The method was validated on frequented tram lines in Budapest and accurately detected severe defects with a hit rate of 100%, with no false alarms. The methodology is also sensitive to moderate and small rail surface defects at the low operational speed.

Normal Plasma Volume Expansion and Micronutrient Status in Pregnancy

Plasma volume expansion is widely known as an important physiologic change in pregnancy, yet normal expansion in healthy pregnancies has not been well described. This expansion influences plasma micronutrient concentrations and may impact interpretation of biomarkers. Our objective was to review studies that measured plasma volume longitudinally across gestation to describe normal plasma volume expansion; secondarily, we examined the impact of plasma volume expansion on micronutrient biomarkers. We systematically searched PubMed for original articles that directly measured plasma volume in pregnant women at more than one time across gestation. We also searched reference lists from these publications for additional papers. We found 15 studies published from 1963 to 2006 that directly measured plasma volume in pregnancy more than one time. We excluded 3 studies because the measurements were not longitudinal and one study because it used an unconventional measurement technique (iron dextran) and some values appeared extreme. Of the 11 longitudinal studies included, 8 studies were conducted in the UK and one each was conducted in India, Chile, and Nigeria. All studies used the Evans blue dye (T‐1824) indicator dilution method to measure the plasma volume. The total number of women in all studies was 524; study size ranged from 11 to 95. Plasma volume was measured 3 to 7 times in women across the studies. Two studies measured plasma volume before conception and 5 studies measured postpartum values (6–8 weeks after birth) as a proxy for pre‐conception. Plasma volume increases varied across the studies. Plasma volume increased by 8% between preconception and 12 weeks, 18% by 16 weeks, 27% by 20 weeks and 36% by 25 weeks gestation. The maximum mean plasma volume increase was 52% (1267 ± 38 ml) at 33–34 weeks gestation. This peak mean expansion ranged from 48% to 59% (1218 to 1323 ml) across studies, while reports of expansion for individual women ranged from 25% to 80%. Plasma volume slightly declined from late third trimester to term. Only one plasma volume study measured micronutrient status. In that study, plasma zinc concentrations declined across gestation to 30 weeks but intravascular zinc mass (the product of zinc concentration and plasma volume) increased across pregnancy. Plasma copper concentration increased up to gestational week 35 but intravascular copper mass was not reported. Few studies have measured plasma volume longitudinally in pregnancy. Studies of healthy pregnancies similarly show plasma volume increases progressively to approximately 52% above the non‐pregnant state in the third trimester with a slight decline to term. Plasma zinc concentration changes in pregnancy did not reflect actual changes in zinc status. Future studies in pregnancy should measure plasma volume to have a valid estimation of micronutrient status and to understand underlying physiologic changes that may be related to adverse outcomes.Support or Funding InformationNIH BIRCWH 12HD055882 (Dr. Gernand)

Interest rate risk in bond investment: Unconventional measurement methods

Interest rate risk of a bond is typically measured by means of duration and convexity. However, these measurements are based on the assumption of a flat yield curve and its parallel shifts. For the purpose of modelling more realistic cases, their modifications are used. Fisher-Weil duration is used to measure the sensitivity to parallel movements of a non-flat yield curve. M-absolute and M-square indicate to which extent a bond portfolio is immunized to nonparallel shifts of the yield curve, taking into account the given time horizon of the concerned investment. A non-flat yield curve can also be approximated by a set of selected key rates, whose duration and convexity measure the portfolio's sensitivity to the changes in specific interest rates.

ChemInform Abstract: New Directions in Electron Paramagnetic Resonance Spectroscopy on Molecular Nanomagnets

AbstractReview: 204 refs.

An experimental approach to efficiency calibration for gamma-ray spectrometric analysis of large air particulate filters

A full-energy-peak efficiency (FEPE) calibration procedure for gamma-ray spectrometric analysis of air particulate samples collected on large filters is described herein. The experimental results are obtained for an unconventional measurement geometry, termed a “packet-sample”. The sample is obtained from a large cellulose filter (45cm×45cm) used to collect air particulate samples that is resized to dimensions suitable for spectrometric measurements (6cm×6cm×0.7cm). To determine the FEPEs, many standards were created, i.e., some filters containing a small amount of ThO2 and others containing a known amount of KCl.Efficiency curves obtained through best fits to experimental data for three high-purity germanium (HPGe) detectors, one of them for X-ray measurement, cover the energy range from 40keV to 2600keV. To validate the efficiency calibration procedure two experimental tests with the use of calibrated sources were conducted and, as application example, airborne concentrations of 131I (particulate matter), 134Cs and 137Cs at Palermo (Italy) in the days following the Fukushima accident in Japan were evaluated.

Determining the distance to a ferromagnetic object with unknown magnetic characteristics

The possibilities for determining the distance to a ferromagnetic object with unknown magnetic characteristics by the measurement of its magnetic field at two spatial points are considered. An unconventional measurement device, which allows us to determine the distance to an object in real time, as well as an algorithm and software for the processing of measurement results with the computer-generated visualization of the parameters of a magnetic field induced by an object, were developed. The error in determining the distance to a sought object does not exceed 20.0%.

Formation of a Copper Oxide Layer as a Key Step in the Metallic Copper Deposition Mechanism

This paper demonstrates the formation of a Cu(OH)1.5Cl0.5 layer as a key step in the metallic copper electrodeposition mechanism in sulfate solutions. This layer is located surprisingly into the metal/solution interface and not on the reaction substrate. The difficult to study metal/solution interface makes indispensable the use of unconventional measurement techniques. In this way, a careful in situ study by means of acoustic impedance techniques associated with gravimetric techniques allowed the growth of this layer during the metallic copper electrodeposition process to be monitored, probably for the first time.

Hybrid adaptive control

Synthesis of a controller for a random parameter linear system is difficult when the state measurements contain noise. Although representational results have been derived, no explicit solution has been obtained in any reasonably general circumstance. An approximation to the quadratic-optimal regulator problem is presented for a situation in which there is an unconventional measurement architecture. The solution is in a form quite similar to that obtained in the complete observation case, but the gain equation is made more complicated by the presence of noise.

Measurements of stresses, forces and moments on nuclear steam generators

Regulatory demands required that strain-gage measurements be made on a steam drum/steam generator assembly to ensure that ASME code limits would not be exceeded during operation. The major difficulty in the performance of this measurement project was centered primarily on the lack of accurate information on the thermal-expansion behavior of the components to be instrumented. In addition, another difficulty in the performance of the measurements was the effect of unknown through-wall thermally induced stresses on the strain-gage readings. To overcome these significant obstacles, an unconventional measurement approach was developed for the analysis of strain-gage measurements. This approach enabled known information on internal steamgenerator steam pressure to be substituted for the unknown information (as described above) which is usually required for strain-gage analysis. This approach has been successfully verified and may have widespread applicability for other measurement projects which face the same commonly encountered difficulties.

Determination of the Parameters of Cavities Terminating Transmission Lines

Past methods available for measuring parameters of cavities terminating transmission lines are often considered too involved for production line testing. One common method requires many individual standing wave ratio measurements at frequencies slightly lower and higher than the resonant frequency of the cavity. These measurements take not only an excessive length of time but also require an accurately controlled variable frequency oscillator for precision measurements. A second method in which an oscillographic display of reflected power is used, while much faster, requires more complicated equipment and calls for use of unconventional measurement procedures. The method presented herein was devised to meet time and accuracy requirements on the production line. Its speedy results can be obtained from equipment and calculations with which production line personnel are familiar. Use is made of the same common sweep frequency method utilized in testing transmission and absorption cavities. This paper presents a derivation of the theory of the method, a description of the apparatus used, and a comparison of the results obtained with this and the point by point method.