Статті в журналах з теми "Robust weak measurement"
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1
Betz, Timm. "Robust Estimation with Nonrandom Measurement Error and Weak Instruments." Political Analysis 21, no. 1 (2013): 86–96. http://dx.doi.org/10.1093/pan/mps037.
Повний текст джерелаАнотація:
Two common problems in applications of two-stage least squares (2SLS) are nonrandom measurement error in the endogenous variable and weak instruments. In the presence of nonrandom measurement error, 2SLS yields inconsistent estimates. In the presence of weak instruments, confidence intervals andp-values can be severely misleading. This article introduces a rank-based estimator, grounded in randomization inference, which addresses both problems within a unified framework. Monte Carlo studies illustrate the deficiencies of 2SLS and the virtues of the rank-based estimator in terms of bias and efficiency. A replication of a study of the effect of economic shocks on democratic transitions demonstrates the practical implications of accounting for nonrandom measurement error and weak instruments.
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Bhuvaneswari, S., R. Muthuganesan, and R. Radha. "Signatures of intrinsic decoherence and weak measurement on quantum correlations." Laser Physics Letters 19, no. 1 (December 2, 2021): 015204. http://dx.doi.org/10.1088/1612-202x/ac3b41.
Повний текст джерелаАнотація:
Abstract In this article, we consider a pair of spin-1/2 particles with squeezing coupling serving as the physical carrier of quantum information. We then examine the dynamics of quantum correlation quantified by the entanglement and measurement-induced nonlocality (MIN) under the intrinsic decoherence. The impact of intrinsic decoherence on the dynamical behaviors of quantum correlations is investigated. We show that the MIN quantities are more robust, while intrinsic decoherence cause sudden death in entanglement. Besides, we highlight the role of spin squeezing coupling and external magnetic field on quantum correlation measures. Finally, we investigate the impact of weak measurement on MIN.
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Faujdar, Jyoti, and Atul Kumar. "Analysing the Efficiencies of Partially Entangled Three-Qubit States for Quantum Information Processing Under Real Conditions." Zeitschrift für Naturforschung A 74, no. 6 (June 26, 2019): 523–37. http://dx.doi.org/10.1515/zna-2018-0521.
Повний текст джерелаАнотація:
AbstractIn this article, we revisit the question of analysing the efficiencies of partially entangled states in three-qubit classes under real conditions. Our results show some interesting observations regarding the efficiencies and correlations of partially entangled states. Surprisingly, we find that the efficiencies of many three-qubit partially entangled states exceed that of maximally entangled three-qubit states under real noisy conditions and applications of weak measurements. Our analysis, therefore, suggests that the efficiencies of partially entangled states are much more robust to noise than those of maximally entangled states at least for the GHZ (Greenberger–Horne–Zeilinger) class states, for certain protocols; i.e. less correlations in the initially prepared state may also lead to better efficiency and hence one need not always consider starting with a maximally entangled state with maximum correlations between the qubits. For a set of partially entangled states, we find that the efficiency is optimal, independent of the decoherence and state parameters, if the value of weak measurement parameter is very large. For other values of the weak measurement parameter, the robustness of the states depends on the decoherence and state parameters. Moreover, we further show that one can achieve higher efficiencies in a protocol by using non-optimal weak measurement strengths instead of optimal weak measurement strengths.
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Gebhart, Valentin, Kyrylo Snizhko, Thomas Wellens, Andreas Buchleitner, Alessandro Romito, and Yuval Gefen. "Topological transition in measurement-induced geometric phases." Proceedings of the National Academy of Sciences 117, no. 11 (March 2, 2020): 5706–13. http://dx.doi.org/10.1073/pnas.1911620117.
Повний текст джерелаАнотація:
The state of a quantum system, adiabatically driven in a cycle, may acquire a measurable phase depending only on the closed trajectory in parameter space. Such geometric phases are ubiquitous and also underline the physics of robust topological phenomena such as the quantum Hall effect. Equivalently, a geometric phase may be induced through a cyclic sequence of quantum measurements. We show that the application of a sequence of weak measurements renders the closed trajectories, hence the geometric phase, stochastic. We study the concomitant probability distribution and show that, when varying the measurement strength, the mapping between the measurement sequence and the geometric phase undergoes a topological transition. Our finding may impact measurement-induced control and manipulation of quantum states—a promising approach to quantum information processing. It also has repercussions on understanding the foundations of quantum measurement.
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Peng, Gang, Zezao Lu, Jiaxi Peng, Dingxin He, Xinde Li, and Bin Hu. "Robust Tightly Coupled Pose Measurement Based on Multi-Sensor Fusion in Mobile Robot System." Sensors 21, no. 16 (August 17, 2021): 5522. http://dx.doi.org/10.3390/s21165522.
Повний текст джерелаАнотація:
Currently, simultaneous localization and mapping (SLAM) is one of the main research topics in the robotics field. Visual-inertia SLAM, which consists of a camera and an inertial measurement unit (IMU), can significantly improve robustness and enable scale weak-visibility, whereas monocular visual SLAM is scale-invisible. For ground mobile robots, the introduction of a wheel speed sensor can solve the scale weak-visibility problem and improve robustness under abnormal conditions. In this paper, a multi-sensor fusion SLAM algorithm using monocular vision, inertia, and wheel speed measurements is proposed. The sensor measurements are combined in a tightly coupled manner, and a nonlinear optimization method is used to maximize the posterior probability to solve the optimal state estimation. Loop detection and back-end optimization are added to help reduce or even eliminate the cumulative error of the estimated poses, thus ensuring global consistency of the trajectory and map. The outstanding contribution of this paper is that the wheel odometer pre-integration algorithm, which combines the chassis speed and IMU angular speed, can avoid the repeated integration caused by linearization point changes during iterative optimization; state initialization based on the wheel odometer and IMU enables a quick and reliable calculation of the initial state values required by the state estimator in both stationary and moving states. Comparative experiments were conducted in room-scale scenes, building scale scenes, and visual loss scenarios. The results showed that the proposed algorithm is highly accurate—2.2 m of cumulative error after moving 812 m (0.28%, loopback optimization disabled)—robust, and has an effective localization capability even in the event of sensor loss, including visual loss. The accuracy and robustness of the proposed method are superior to those of monocular visual inertia SLAM and traditional wheel odometers.
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Kannawadi, Arun, Erik Rosenberg, and Henk Hoekstra. "Mitigating the effects of undersampling in weak lensing shear estimation with metacalibration." Monthly Notices of the Royal Astronomical Society 502, no. 3 (January 29, 2021): 4048–63. http://dx.doi.org/10.1093/mnras/stab211.
Повний текст джерелаАнотація:
ABSTRACT metacalibration is a state-of-the-art technique for measuring weak gravitational lensing shear from well-sampled galaxy images. We investigate the accuracy of shear measured with metacalibration from fitting elliptical Gaussians to undersampled galaxy images. In this case, metacalibration introduces aliasing effects leading to an ensemble multiplicative shear bias about 0.01 for Euclid and even larger for the Roman Space Telescope, well exceeding the missions’ requirements. We find that this aliasing bias can be mitigated by computing shapes from weighted moments with wider Gaussians as weight functions, thereby trading bias for a slight increase in variance of the measurements. We show that this approach is robust to the point-spread function in consideration and meets the stringent requirements of Euclid for galaxies with moderate to high signal-to-noise ratios. We therefore advocate metacalibration as a viable shear measurement option for weak lensing from upcoming space missions.
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Shea, Mark J., Anika Weightman, Bradley Wibrow, and Matthew H. Anstey. "A Prospective Evaluation of Grip Strength Comparing a Low-Tech Method to Dynanometry in Preoperative Surgical Patients and Weak Intensive Care Patients." Critical Care Research and Practice 2022 (October 19, 2022): 1–6. http://dx.doi.org/10.1155/2022/3428851.
Повний текст джерелаАнотація:
Objective. Grip strength testing offers a mechanism to identify patients in whom frailty might be present, discriminate between robust elderly and vulnerable younger patients, and can be used as a tool to track changes in muscle bulk over the course of an inpatient stay. We compared gold-standard quantitative grip strength measurement to a low-tech alternative, a manual bedside sphygmomanometer. Design. Under supervision, subjects performed hand-grip strength testing with each instrument. A mean score is calculated from three measurements on the dominant and nondominant hand. Setting. Testing was performed in a tertiary centre in Perth, Western Australia, in both outpatient clinics and intensive care units. Participants. 51 adult pre-operative surgical outpatients were assessed, alongside 20 intensive care inpatients identified as being weak. Main outcome measures. A statistical correlation between the two measures was evaluated. Feasibility, safety, and convenience were also assessed in outpatient and bedside settings. Results. Highly correlated results in both tertiary surgical outpatients (rs = 0.895, p ≤ 0.001 , N = 102; r (100) = 0.899, p ≤ 0.001 ) and weak intensive care patients (rs = 0.933, p ≤ 0.001 , N = 39 r (37) = 0.935, p ≤ 0.001 ) Conclusions. Modifying a manual bedside sphygmomanometer to measure grip strength is feasible and correlates well with a formal dynamometer in preadmission surgical patients and weak patients in the intensive care unit. The use of an existing, safe, and available device removes barriers to the measurement of weakness in patients and may encourage uptake of objective measurement in multiple settings.
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Takeuchi, Kiyoshi, Tomoko Mizutani, Takuya Saraya, Masaharu Kobayashi, and Toshiro Hiramoto. "A robust single device MOSFET series resistance extraction method considering horizontal-field-dependent mobility." Japanese Journal of Applied Physics 61, SC (February 10, 2022): SC1016. http://dx.doi.org/10.35848/1347-4065/ac3eb7.
Повний текст джерелаАнотація:
Abstract A simple MOSFET series resistance extraction method using multiple drain current versus gate voltage curves of a single device is proposed, where mobility modulation by a horizontal electric field (i.e., weak velocity saturation) is taken into account. The method is validated using TCAD, where series resistance determined from internal potential distributions was used as a reliable reference. Measurement results were also obtained which further support the validity of the method.
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Bae, Junhyung. "Cost-Effective Placement of Phasor Measurement Units to Defend against False Data Injection Attacks on Power Grid." Energies 13, no. 15 (July 28, 2020): 3862. http://dx.doi.org/10.3390/en13153862.
Повний текст джерелаАнотація:
This study presents the phasor measurement unit (PMU) placement strategy in the presence of false data injection attacks which is one of the most serious security threats against power grid. It is focused on applications related to supervisory control and data acquisition (SCADA) systems where measurement data can be easily corrupted by adversaries without getting caught by the system. To safeguard power grids against malicious attacks, procedures have been proposed to facilitate the placement of secure PMUs to defend against false data injection attacks in a highly cost-effective way. It has formulated a method of identifying measurements that are vulnerable to false data injection attacks. It was discovered that a weak power grid can be transformed into a robust power grid by adding a few PMUs at vulnerable locations. Simulations on the IEEE standard test systems demonstrate the benefits of the proposed procedure.
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Zhao, Chunran, Mengzheng Zhu, and Liu Ye. "Robust scheme for the preparation of polarization-photon cluster state with homodyne measurement via weak cross-Kerr nonlinearity." Journal of the Optical Society of America B 28, no. 7 (June 24, 2011): 1740. http://dx.doi.org/10.1364/josab.28.001740.
Повний текст джерела
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Min, Lingtong, Qinyi Lv, Laisen Nie, and Deyun Zhou. "Anti-Interference Heartbeat Measurement Based on a Miniaturized Doppler Radar Sensor." Advances in Mathematical Physics 2021 (August 18, 2021): 1–11. http://dx.doi.org/10.1155/2021/1620938.
Повний текст джерелаАнотація:
It is a hot topic to utilize the Doppler radar sensor in noncontact biosignal monitoring nowadays. Unfortunately, most detections are easily affected by interference or strong noise. Even slight body movements can cause serious demodulation distortion. In this paper, we proposed a novel algorithm to solve the sudden and unexpected interference. Firstly, the one-dimensional signal detected by the sensor is divided into segments to form a two-dimensional data matrix. In both the intrasegment and intersegment domains of the data matrix, a robust algorithm is employed to suppress unwanted interference, which significantly improves the robustness of demodulation. Experiments show the effectiveness of the proposed algorithm, based on which weak heartbeat signal hidden in the interference can be well extracted.
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Jiang, Xiao-Lei, Yang Wang, Yi-Fei Lu, Jia-Ji Li, Chun Zhou, and Wan-Su Bao. "Security Analysis of Sending or Not-Sending Twin-Field Quantum Key Distribution with Weak Randomness." Entropy 24, no. 10 (September 23, 2022): 1339. http://dx.doi.org/10.3390/e24101339.
Повний текст джерелаАнотація:
Sending-or-not sending twin-field quantum key distribution (SNS TF-QKD) has the advantage of tolerating large amounts of misalignment errors, and its key rate can exceed the linear bound of repeaterless quantum key distribution. However, the weak randomness in a practical QKD system may lower the secret key rate and limit its achievable communication distance, thus compromising its performance. In this paper, we analyze the effects of the weak randomness on the SNS TF-QKD. The numerical simulation shows that SNS TF-QKD can still have an excellent performance under the weak random condition: the secret key rate can exceed the PLOB boundary and achieve long transmission distances. Furthermore, our simulation results also show that SNS TF-QKD is more robust to the weak randomness loopholes than the BB84 protocol and the measurement-device-independent QKD (MDI-QKD). Our results emphasize that keeping the randomness of the states is significant to the protection of state preparation devices.
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Pokarowska, Maria. "Comparison of robust estimators for leveling networks in Monte Carlo simulations." Reports on Geodesy and Geoinformatics 101, no. 1 (June 1, 2016): 70–81. http://dx.doi.org/10.1515/rgg-2016-0023.
Повний текст джерелаАнотація:
Abstract We compared the method of least squares (LS), Pope’s iterative data snooping (IDS) and Huber’s M-estimator (HU) in realistic leveling networks, for which the heights or the vertical displacements of points are known. The study was conducted using the Monte Carlo simulation, in which one repeatedly generates sets of observations related to the measurement data, then calculates values of the estimators and, finally, assesses it with respect to the real coordinates. To simulate outliers we used popular mixture models with two or more normal distributions. It is shown that for small, strong networks robust methods IDS and HU are more accurate than LS, but for large, weak networks occurring in practice there is no significant difference between the considered methods in the accuracy of the solution.
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Dong, Bo, and Kai Zhang. "A Tightly Coupled Visual-Inertial GNSS State Estimator Based on Point-Line Feature." Sensors 22, no. 9 (April 28, 2022): 3391. http://dx.doi.org/10.3390/s22093391.
Повний текст джерелаАнотація:
Visual-inertial odometry (VIO) is known to suffer from drifting and can only provide local coordinates. In this paper, we propose a tightly coupled GNSS-VIO system based on point-line features for robust and drift-free state estimation. Feature-based methods are not robust in complex areas such as weak or repeated textures. To deal with this problem, line features with more environmental structure information can be extracted. In addition, to eliminate the accumulated drift of VIO, we tightly fused the GNSS measurement with visual and inertial information. The GNSS pseudorange measurements are real-time and unambiguous but experience large errors. The GNSS carrier phase measurements can achieve centimeter-level positioning accuracy, but the solution to the whole-cycle ambiguity is complex and time-consuming, which degrades the real-time performance of a state estimator. To combine the advantages of the two measurements, we use the carrier phase smoothed pseudorange instead of pseudorange to perform state estimation. Furthermore, the existence of the GNSS receiver and IMU also makes the extrinsic parameter calibration crucial. Our proposed system can calibrate the extrinsic translation parameter between the GNSS receiver and IMU in real-time. Finally, we show that the states represented in the ECEF frame are fully observable, and the tightly coupled GNSS-VIO state estimator is consistent. We conducted experiments on public datasets. The experimental results demonstrate that the positioning precision of our system is improved and the system is robust and real-time.
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Haque, Md Rejwanul, Greg Berkeley, and Xiangrong Shen. "Force-Moment Sensor for Prosthesis Structural Load Measurement." Sensors 23, no. 2 (January 13, 2023): 938. http://dx.doi.org/10.3390/s23020938.
Повний текст джерелаАнотація:
Measurement of prosthesis structural load, as an important way to quantify the interaction of the amputee user with the environment, may serve important purposes in the control of smart lower-limb prosthetic devices. However, the majority of existing force sensors used in protheses are developed based on strain measurement and thus may suffer from multiple issues such as weak signals and signal drifting. To address these limitations, this paper presents a novel Force-Moment Prosthesis Load Sensor (FM-PLS) to measure the axial force and bending moment in the structure of a lower-limb prosthesis. Unlike strain gauge-based force sensors, the FM-PLS is developed based on the magnetic sensing of small (millimeter-scale) deflection of an elastic element, and it may provide stronger signals that are more robust against interferences and drifting since such physical deflection is several orders of magnitude greater than the strain of a typical load-bearing structure. The design of the sensor incorporates uniquely curved supporting surfaces such that the measurement is sensitive to light load but the sensor structure is robust enough to withstand heavy load without damage. To validate the sensor performance, benchtop testing of the FM-PLS and walking experiments of a FM-PLS-embedded robotic lower-limb prosthesis were conducted. Benchtop testing results displayed good linearity and a good match to the numerical simulation results. Results from the prosthesis walking experiments showed that the sensor signals can be used to detect important gaits events such as heel strike and toe-off, facilitating the reliable motion control of lower-limb prostheses.
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FANG, BIN, XINGE YOU, WEN-SHENG CHEN, and YUAN YAN TANG. "MATCHING ALGORITHM USING WAVELET THINNING FEATURES FOR OFFLINE SIGNATURE VERIFICATION." International Journal of Wavelets, Multiresolution and Information Processing 05, no. 01 (January 2007): 27–38. http://dx.doi.org/10.1142/s021969130700163x.
Повний текст джерелаАнотація:
Structure distortion evaluation allows us to directly measure the similarity between signature patterns without classification using feature vectors, which usually suffers from limited training samples. In this paper, we incorporate the merits of both global and local alignment algorithms to define structure distortion using signature skeletons identified by a robust wavelet thinning technique. A weak affine model is employed to globally register two signature skeletons and structure distortion between two signature patterns, which are determined by applying an elastic local alignment algorithm. Similarity measurement is evaluated in the form of Euclidean distance of all found corresponding feature points. Experimental results showed that the proposed similarity measurement was able to provide sufficient discriminatory information in terms of equal error rate being 18.6% with four training samples.
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Hempel, Sabrina, Julian Adolphs, Niels Landwehr, Dilya Willink, David Janke, and Thomas Amon. "Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation." Applied Sciences 10, no. 19 (October 3, 2020): 6938. http://dx.doi.org/10.3390/app10196938.
Повний текст джерелаАнотація:
A reliable quantification of greenhouse gas emissions is a basis for the development of adequate mitigation measures. Protocols for emission measurements and data analysis approaches to extrapolate to accurate annual emission values are a substantial prerequisite in this context. We systematically analyzed the benefit of supervised machine learning methods to project methane emissions from a naturally ventilated cattle building with a concrete solid floor and manure scraper located in Northern Germany. We took into account approximately 40 weeks of hourly emission measurements and compared model predictions using eight regression approaches, 27 different sampling scenarios and four measures of model accuracy. Data normalization was applied based on median and quartile range. A correlation analysis was performed to evaluate the influence of individual features. This indicated only a very weak linear relation between the methane emission and features that are typically used to predict methane emission values of naturally ventilated barns. It further highlighted the added value of including day-time and squared ambient temperature as features. The error of the predicted emission values was in general below 10%. The results from Gaussian processes, ordinary multilinear regression and neural networks were least robust. More robust results were obtained with multilinear regression with regularization, support vector machines and particularly the ensemble methods gradient boosting and random forest. The latter had the added value to be rather insensitive against the normalization procedure. In the case of multilinear regression, also the removal of not significantly linearly related variables (i.e., keeping only the day-time component) led to robust modeling results. We concluded that measurement protocols with 7 days and six measurement periods can be considered sufficient to model methane emissions from the dairy barn with solid floor with manure scraper, particularly when periods are distributed over the year with a preference for transition periods. Features should be normalized according to median and quartile range and must be carefully selected depending on the modeling approach.
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Altmann, Yoann, Stephen McLaughlin, Miles J. Padgett, Vivek K. Goyal, Alfred O. Hero, and Daniele Faccio. "Quantum-inspired computational imaging." Science 361, no. 6403 (August 16, 2018): eaat2298. http://dx.doi.org/10.1126/science.aat2298.
Повний текст джерелаАнотація:
Computational imaging combines measurement and computational methods with the aim of forming images even when the measurement conditions are weak, few in number, or highly indirect. The recent surge in quantum-inspired imaging sensors, together with a new wave of algorithms allowing on-chip, scalable and robust data processing, has induced an increase of activity with notable results in the domain of low-light flux imaging and sensing. We provide an overview of the major challenges encountered in low-illumination (e.g., ultrafast) imaging and how these problems have recently been addressed for imaging applications in extreme conditions. These methods provide examples of the future imaging solutions to be developed, for which the best results are expected to arise from an efficient codesign of the sensors and data analysis tools.
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Avetisov, Viacheslav, Ove Bjoroey, Junyang Wang, Peter Geiser, and Ketil Gorm Paulsen. "Hydrogen Sensor Based on Tunable Diode Laser Absorption Spectroscopy." Sensors 19, no. 23 (December 3, 2019): 5313. http://dx.doi.org/10.3390/s19235313.
Повний текст джерелаАнотація:
A laser-based hydrogen (H2) sensor using wavelength modulation spectroscopy (WMS) was developed for the contactless measurement of molecular hydrogen. The sensor uses a distributed feedback (DFB) laser to target the H2 quadrupole absorption line at 2121.8 nm. The H2 absorption line exhibited weak collisional broadening and strong collisional narrowing effects. Both effects were investigated by comparing measurements of the absorption linewidth with detailed models using different line profiles including collisional narrowing effects. The collisional broadening and narrowing parameters were determined for pure hydrogen as well as for hydrogen in nitrogen and air. The performance of the sensor was evaluated and the sensor applicability for H2 measurement in a range of 0–10 %v of H2 was demonstrated. A precision of 0.02 %v was achieved with 1 m of absorption pathlength (0.02 %v∙m) and 1 s of integration time. For the optimum averaging time of 20 s, precision of 0.005 %v∙m was achieved. A good linear relationship between H2 concentration and sensor response was observed. A simple and robust transmitter–receiver configuration of the sensor allows in situ installation in harsh industrial environments.
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Hildebrandt, H., F. Köhlinger, J. L. van den Busch, B. Joachimi, C. Heymans, A. Kannawadi, A. H. Wright, et al. "KiDS+VIKING-450: Cosmic shear tomography with optical and infrared data." Astronomy & Astrophysics 633 (January 2020): A69. http://dx.doi.org/10.1051/0004-6361/201834878.
Повний текст джерелаАнотація:
We present a tomographic cosmic shear analysis of the Kilo-Degree Survey (KiDS) combined with the VISTA Kilo-Degree Infrared Galaxy Survey. This is the first time that a full optical to near-infrared data set has been used for a wide-field cosmological weak lensing experiment. This unprecedented data, spanning 450 deg2, allows us to significantly improve the estimation of photometric redshifts, such that we are able to include robustly higher-redshift sources for the lensing measurement, and – most importantly – to solidify our knowledge of the redshift distributions of the sources. Based on a flat ΛCDM model we find S8 ≡ σ8 Ωm/0.3 = 0.737+0.040−0.036 in a blind analysis from cosmic shear alone. The tension between KiDS cosmic shear and the Planck-Legacy CMB measurements remains in this systematically more robust analysis, with S8 differing by 2.3σ. This result is insensitive to changes in the priors on nuisance parameters for intrinsic alignment, baryon feedback, and neutrino mass. KiDS shear measurements are calibrated with a new, more realistic set of image simulations and no significant B-modes are detected in the survey, indicating that systematic errors are under control. When calibrating our redshift distributions by assuming the 30-band COSMOS-2015 photometric redshifts are correct (following the Dark Energy Survey and the Hyper Suprime-Cam Survey), we find the tension with Planck is alleviated. The robust determination of source redshift distributions remains one of the most challenging aspects for future cosmic shear surveys.
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Moum, James N. "Ocean Speed and Turbulence Measurements Using Pitot-Static Tubes on Moorings." Journal of Atmospheric and Oceanic Technology 32, no. 7 (July 2015): 1400–1413. http://dx.doi.org/10.1175/jtech-d-14-00158.1.
Повний текст джерелаАнотація:
AbstractA low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation is described and evaluated. The measurement of speed is derived from differential pressure via Bernoulli’s principle. The differential pressure sensor employed here has relatively small, but significant, adverse sensitivities to static pressure, temperature, and acceleration, which are characterized in tests in the college’s laboratory. Results from field tests on moorings indicate acceptable agreement in pitot-static speed measurements with independent acoustic Doppler current profiler speeds, characterized as linear fits with slope = 1 (95% confidence), ±0.02 m s−1 bias, and root-mean-square error of residuals (observed minus fitted values) = 0.055 m s−1. Direct estimates of are derived from fits of velocity spectra to a theoretical turbulence inertial subrange. From near-bottom measurements, these estimates are interpreted as seafloor friction velocities, which yield drag coefficients consistent with expected values. Noise levels for , based on 40-min spectral fits, are <10–9 m2 s–3. In comparison to the airfoil (or shear) probe, the pitot-static tube provides the full spectrum of velocity, not just the dissipation range of the spectrum. In comparison to acoustic measurements of velocity, the pitot-static tube does not require acoustic scatters in the measurement volume. This makes the sensor a candidate for use in the deep ocean, for example, where acoustic scatterers are weak.
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Mesarosova, Karina, Alex B. Siegling, Rachel A. Plouffe, Donald H. Saklofske, Martin M. Smith, and Paul F. Tremblay. "Personality Measurement and Profile in a European Sample of Civil Airline Pilots." European Journal of Psychological Assessment 35, no. 6 (November 2019): 791–800. http://dx.doi.org/10.1027/1015-5759/a000466.
Повний текст джерелаАнотація:
Abstract. The study examined the psychometric properties of the Revised NEO Personality Inventory (NEO PI-R, UK edition) in a large European sample of civil airline pilots. The NEO PI-R is a comprehensive and robust measure of personality that has been validated across cultures and contexts. Furthermore, the personality profile of the pilot sample was examined and compared to a normative sample representing the UK working population. Data from 591 pilots (95.1% male) were collected. Analyses include the internal reliability and factorial validity (precisely, Exploratory Structural Equation Modeling) to examine the measurement equivalence of the NEO PI-R with reference to UK norms ( N = 1,301). Internal reliability estimates of the NEO PI-R scores were good at the domain level, but generally weak at the facet level. The structural model in the pilot sample was congruent with the general working population sample. Furthermore, there was convincing evidence for a distinct personality profile of civil pilots, although the stability of this profile will require further validation. The NEO PI-R’s validity in the assessment of general personality in civil airline pilots is discussed, along with implications of the results for the utility of personality assessment in civil aviation contexts.
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Thompson, John M., Stephen C. H. Smith, Robert Cramb, and Peter Hutton. "Clinical Evaluation of Sodium Ion Selective Field Effect Transistors for Whole Blood Assay." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 31, no. 1 (January 1994): 12–17. http://dx.doi.org/10.1177/000456329403100102.
Повний текст джерелаАнотація:
Sodium ion selective field effect transistors (ISFETs) were evaluated for their performance in measurement of sodium ions in whole blood for ‘near patient’ analysis in operating theatres and intensive care units. Performance was evaluated in comparison with a standard clinical laboratory sodium/potassium ion analyser (Radiometer KNA1) and with sodium and potassium assays using flame photometry on the plasma from each whole blood specimen. The imprecisions (coefficients of variation) of three ISFETs for sodium ion assay were 1·08, 1·56 and 1·10%, respectively. Robust bivariate linear regression (reweighted least squares preceded by least median of squares) of the ISFET versus KNA1 sodium ion activity yielded a regression coefficient of 1·08 and an intercept of −18·2 mM. The influence of potassium, protein and lipid on the measurement of sodium ions by both ISFETs and the KNA1 was assessed using robust multiple regression (also based on reweighted least squares preceded by least median of squares). In the regression versus flame photometry, protein was found to be more influential for the KNA1 (glass sodium ion selective electrode) than for the ISFET. Potassium had no influence on assays using the ISFET, but had a weak negative influence on assays using the KNA1. Two ISFETs lasted for more than 200 assays each demonstrating their robustness in the assay of whole blood.
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Klokov, Andrey, Motayam Kanouj, and Aleksandr Mironchev. "A Novel Carrier Tracking Approach for GPS Signals Based on Gauss–Hermite Kalman Filter." Electronics 11, no. 14 (July 15, 2022): 2215. http://dx.doi.org/10.3390/electronics11142215.
Повний текст джерелаАнотація:
In a conventional GPS receiver, the carrier tracking system is the key stage that keeps the receiver locked to the radio navigation parameters (RNPs) of the received signal. The most commonly used approaches to the tracking system are phase lock loop (PLL), frequency lock loop (FLL), and FLL-assisted PLL. The main limitation of the above approaches is that their performance deteriorates when working with weak signals and in harsh environments. In recent years, Kalman filter (KF)-based tracking loop architectures have gained increased attention due to their robust and better performance compared with conventional architectures. In this paper, a novel Gauss–Hermite Kalman filtering-based carrier tracking algorithm is proposed for static and moving receivers with weak GPS signals. The performance of the proposed algorithm is compared with two other approaches: extended Kalman filter (EKF) and unscented Kalman filter (UKF). Simulations were conducted using a software-defined GPS simulator and software device radio (SDR) modules. A comparative analysis of the tracking methods demonstrated that the proposed tracking method shows a better performance and improves the tracking sensitivity and capability under weak signal conditions as compared with EKF- and UKF-based tracking methods. In addition, the results show that the proposed approach improves the Doppler frequency measurement accuracy under dynamic operation conditions.
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Fu, Haocheng, Xianfeng Zhao, and Xiaolei He. "Improving Anticompression Robustness of JPEG Adaptive Steganography Based on Robustness Measurement and DCT Block Selection." Security and Communication Networks 2021 (December 18, 2021): 1–15. http://dx.doi.org/10.1155/2021/9153468.
Повний текст джерелаАнотація:
With the development of the Internet, social network platforms (SNPs) have become the most common channel for image sharing. As a result, transmitting stego images in the public channels gives steganographers the best opportunity to transmit secret messages with behavioral security preserved. However, the SNPs typically compress uploaded images and damage the weak signal of steganography. In this study, a robust JPEG steganographic scheme based on robustness measurement and cover block selection (CBSRS) is proposed. We first design a deep learning-based model to fit the blockwise change rate of coefficients after JPEG recompression. Then, a cover block selection strategy is proposed to improve the robustness by optimizing the joint distortion function of transmission costs and classic costs. Moreover, by embedding indicator of cover block selection in chrominance channels of JPEG images, a shareable cover construction scheme is designed to solve the problem of auxiliary information transmission. The experimental results show that our proposed framework improves robustness while maintaining statistical security. Comparing with state-of-the-art methods, the framework achieves better performance under given recompression channels.
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Wester, Gry, Kristine Bærøe, and Ole Frithjof Norheim. "Towards theoretically robust evidence on health equity: a systematic approach to contextualising equity-relevant randomised controlled trials." Journal of Medical Ethics 45, no. 1 (August 2, 2018): 54–59. http://dx.doi.org/10.1136/medethics-2017-104610.
Повний текст джерелаАнотація:
Reducing inequalities in health and the determinants of health is a widely acknowledged health policy goal, and methods for measuring inequalities and inequities in health are well developed. Yet, the evidence base is weak for how to achieve these goals. There is a lack of high-quality randomised controlled trials (RCTs) reporting impact on the distribution of health and non-health benefits and lack of methodological rigour in how to design, power, measure, analyse and interpret distributional impact in RCTs. Our overarching aim in this paper is to contribute to the emerging effort to improve transparency and coherence in the theoretical and conceptual basis for RCTs on effective interventions to reduce health inequity. We endeavour to achieve this aim by pursuing two more specific objectives. First, we propose an overview of three broader health equity frameworks and clarify their implications for the measurement of health inequality in RCTs. Second, we seek to clarify the relationship between theory and translational challenges that researchers would need to attend to, in order to ensure that equity-relevant RCTs are coherently grounded in theory.
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Barton, Erin E., Rebecca Murray, Cecelia O'Flaherty, Erin M. Sweeney, and Stephanie Gossett. "Teaching Object Play to Young Children With Disabilities: A Systematic Review of Methods and Rigor." American Journal on Intellectual and Developmental Disabilities 125, no. 1 (January 1, 2020): 14–36. http://dx.doi.org/10.1352/1944-7558-125.1.14.
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Abstract In this systematic review, we examined the rigor and outcomes across 27 object play intervention studies using single-case research methodology. We focused on studies including children age 5 years or younger and examined several descriptive characteristics including materials, instructional packages, and settings. We also analyzed the facilitation and measurement of generalized play and several methodological features including quality, rigor, and visual analysis procedures. Overall, the identified studies demonstrated positive outcomes, although quality and rigor limited interpretations of the outcomes. Previous reviews also have noted strong outcomes and weak to moderate quality for single-case studies. Our results should be interpreted with caution given previous reviews of play intervention studies identified strong outcomes and quality from group-design studies. Additional replications testing robust interventions using single-case research with strong methodological rigor are warranted.
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González Hernández, J. I., R. Rebolo, L. Pasquini, G. Lo Curto, P. Molaro, E. Caffau, H. G. Ludwig, et al. "The solar gravitational redshift from HARPS-LFC Moon spectra." Astronomy & Astrophysics 643 (November 2020): A146. http://dx.doi.org/10.1051/0004-6361/202038937.
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Context. The general theory of relativity predicts the redshift of spectral lines in the solar photosphere as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum of the Sun’s reflected light on Solar System bodies. Aims. The laser frequency comb (LFC) calibration system attached to the HARPS spectrograph offers the possibility of performing an accurate measurement of the solar gravitational redshift (GRS) by observing the Moon or other Solar System bodies. Here, we analyse the line shift observed in Fe absorption lines from five high-quality HARPS-LFC spectra of the Moon. Methods. We selected an initial sample of 326 photospheric Fe lines in the spectral range between 476–585 nm and measured their line positions and equivalent widths (EWs). Accurate line shifts were derived from the wavelength position of the core of the lines compared with the laboratory wavelengths of Fe lines. We also used a CO5BOLD 3D hydrodynamical model atmosphere of the Sun to compute 3D synthetic line profiles of a subsample of about 200 spectral Fe lines centred at their laboratory wavelengths. We fit the observed relatively weak spectral Fe lines (with EW< 180 mÅ) with the 3D synthetic profiles. Results. Convective motions in the solar photosphere do not affect the line cores of Fe lines stronger than about ∼150 mÅ. In our sample, only 15 Fe I lines have EWs in the range 150< EW(mÅ) < 550, providing a measurement of the solar GRS at 639 ± 14 m s−1, which is consistent with the expected theoretical value on Earth of ∼633.1 m s−1. A final sample of about 97 weak Fe lines with EW < 180 mÅ allows us to derive a mean global line shift of 638 ± 6 m s−1, which is in agreement with the theoretical solar GRS. Conclusions. These are the most accurate measurements of the solar GRS obtained thus far. Ultrastable spectrographs calibrated with the LFC over a larger spectral range, such as HARPS or ESPRESSO, together with a further improvement on the laboratory wavelengths, could provide a more robust measurement of the solar GRS and further testing of 3D hydrodynamical models.
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Loera, Barbara, Giorgia Molinengo, Marco Miniotti, and Paolo Leombruni. "Refining the Frommelt Attitude Toward the Care of the Dying Scale (FATCOD–B) for medical students: A confirmatory factor analysis and Rasch validation study." Palliative and Supportive Care 16, no. 1 (May 15, 2017): 50–59. http://dx.doi.org/10.1017/s147895151700030x.
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ABSTRACTObjective:Given the increasing number of patients requiring palliative care and the need for more professionals who are able to provide care for the dying comfortably, assessment of medical attitudes toward end-of-life care is becoming a key aspect of medical education. The present study aimed to establish whether the Frommelt Attitude Toward the Care Of the Dying, Form B (FATCOD–B) meets current psychometric standards of validity for an assessment tool in medical education.Method:The participants were 200 undergraduate medical students. Since in a previous study the FATCOD–B was found to have a weak structure due to poor item validity, a refined version was proposed and tested in the present study. Confirmatory factor analysis and the Rasch model were employed to assess its dimensionality and psychometric properties.Results:The construct measured by the FATCOD–B continues to be misspecified. The tool has a two-dimensional structure. The first is well-structured and demonstrates appreciable measurement and discriminant capabilities. The second has low validity because its measurement capabilities are based on weakly correlated items.Significance of results:Our results suggest that the FATCOD–B measures a two-dimensional construct and that only its first dimension is a robust measurement tool for use in medical education to evaluate undergraduates' attitudes about caring for the dying.
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Zhong, Saishang, Mingqiang Guo, Ruina Lv, Jianguo Chen, Zhong Xie, and Zheng Liu. "A Robust Rigid Registration Framework of 3D Indoor Scene Point Clouds Based on RGB-D Information." Remote Sensing 13, no. 23 (November 24, 2021): 4755. http://dx.doi.org/10.3390/rs13234755.
Повний текст джерелаАнотація:
Rigid registration of 3D indoor scenes is a fundamental yet vital task in various fields that include remote sensing (e.g., 3D reconstruction of indoor scenes), photogrammetry measurement, geometry modeling, etc. Nevertheless, state-of-the-art registration approaches still have defects when dealing with low-quality indoor scene point clouds derived from consumer-grade RGB-D sensors. The major challenge is accurately extracting correspondences between a pair of low-quality point clouds when they contain considerable noise, outliers, or weak texture features. To solve the problem, we present a point cloud registration framework in view of RGB-D information. First, we propose a point normal filter for effectively removing noise and simultaneously maintaining sharp geometric features and smooth transition regions. Second, we design a correspondence extraction scheme based on a novel descriptor encoding textural and geometry information, which can robustly establish dense correspondences between a pair of low-quality point clouds. Finally, we propose a point-to-plane registration technology via a nonconvex regularizer, which can further diminish the influence of those false correspondences and produce an exact rigid transformation between a pair of point clouds. Compared to existing state-of-the-art techniques, intensive experimental results demonstrate that our registration framework is excellent visually and numerically, especially for dealing with low-quality indoor scenes.
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Ko, Young-Rae, and Tae-Hyoung Kim. "Feedforward Plus Feedback Control of an Electro-Hydraulic Valve System Using a Proportional Control Valve." Actuators 9, no. 2 (June 15, 2020): 45. http://dx.doi.org/10.3390/act9020045.
Повний текст джерелаАнотація:
The output feedback signal of the electro-hydraulic valve system (EHVS) affects the activation of its right or left envelope function; thus, even weak measurement noise can cause high-frequency switching between the two envelope functions, leading to chattering in the control input. Consequently, feedforward and feedback controllers in a cascaded configuration generate undesirable chattering in the output signal. We propose a practical and reliable control approach for an EHVS actuated by a proportional control valve. The proposed controller has a parallel structure comprising an inverse generalized Prandtl–Ishlinskii (P–I) model-based feedforward controller, with both hydraulic dead-zone and flow saturation limits, for compensating asymmetric hysteretic behavior. Further, the proposed controller comprises a robust proportional-integral-derivative (PID) feedback controller for achieving robustness against disturbances and noises. The proposed parallel structure is independent of the output feedback of the EHVS. Moreover, the proposed robust PID feedback controller guarantees EHVS stability by precisely selecting the cutoff frequency for the sensitivity and complementary sensitivity functions based on the amplitude spectrum of the inverse-model-based feedforward compensation error. The results verify the high reliability of the proposed EHVS control scheme for the precise control of an EHVS actuated by a proportional control valve in practice.
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Cui, Haihua, Wenhe Liao, Xiaosheng Cheng, Ning Dai, and Changye Guo. "Flexible point cloud matching method based on three-dimensional image feature points." Advances in Mechanical Engineering 10, no. 9 (September 2018): 168781401879503. http://dx.doi.org/10.1177/1687814018795032.
Повний текст джерелаАнотація:
Flexible and robust point cloud matching is important for three-dimensional surface measurement. This article proposes a new matching method based on three-dimensional image feature points. First, an intrinsic shape signature algorithm is used to detect the key shape feature points, using a weighted three-dimensional occupational histogram of the data points within the angular space, which is a view-independent representation of the three-dimensional shape. Then, the point feature histogram is used to represent the underlying surface model properties at a point whose computation is based on the combination of certain geometrical relations between the point’s nearest k-neighbors. The two-view point clouds are robustly matched using the proposed double neighborhood constraint of minimizing the sum of the Euclidean distances between the local neighbors of the point and feature point. The proposed optimization method is immune to noise, reduces the search range for matching points, and improves the correct feature point matching rate for a weak surface texture. The matching accuracy and stability of the proposed method are verified using experiments. This method can be used for a flat surface with weak features and in other applications. The method has a larger application range than the traditional methods.
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Poulsen, Melissa N., Brian S. Schwartz, Cara Nordberg, Joseph DeWalle, Jonathan Pollak, Giuseppina Imperatore, Carla I. Mercado, Karen R. Siegel, and Annemarie G. Hirsch. "Association of Greenness with Blood Pressure among Individuals with Type 2 Diabetes across Rural to Urban Community Types in Pennsylvania, USA." International Journal of Environmental Research and Public Health 18, no. 2 (January 13, 2021): 614. http://dx.doi.org/10.3390/ijerph18020614.
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Greenness may impact blood pressure (BP), though evidence is limited among individuals with type 2 diabetes (T2D), for whom BP management is critical. We evaluated associations of residential greenness with BP among individuals with T2D in geographically diverse communities in Pennsylvania. To address variation in greenness type, we evaluated modification of associations by percent forest. We obtained systolic (SBP) and diastolic (DBP) BP measurements from medical records of 9593 individuals following diabetes diagnosis. Proximate greenness was estimated within 1250-m buffers surrounding individuals’ residences using the normalized difference vegetation index (NDVI) prior to blood pressure measurement. Percent forest was calculated using the U.S. National Land Cover Database. Linear mixed models with robust standard errors accounted for spatial clustering; models were stratified by community type (townships/boroughs/cities). In townships, the greenest communities, an interquartile range increase in NDVI was associated with reductions in SBP of 0.87 mmHg (95% CI: −1.43, −0.30) and in DBP of 0.41 mmHg (95% CI: −0.78, −0.05). No significant associations were observed in boroughs or cities. Evidence for modification by percent forest was weak. Findings suggest a threshold effect whereby high greenness may be necessary to influence BP in this population and support a slight beneficial impact of greenness on cardiovascular disease risk.
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Bull, Craig L., Michael W. Johnson, Hayrullo Hamidov, Kazuki Komatsu, Malcolm Guthrie, Matthias J. Gutmann, John S. Loveday, and Richard J. Nelmes. "An improved method for calibrating time-of-flight Laue single-crystal neutron diffractometers." Journal of Applied Crystallography 47, no. 3 (May 29, 2014): 974–83. http://dx.doi.org/10.1107/s1600576714006657.
Повний текст джерелаАнотація:
A robust and comprehensive method for determining the orientation matrix of a single-crystal sample using the neutron Laue time-of-flight (TOF) technique is described. The new method enables the measurement of the unit-cell parameters with an uncertainty in the range 0.015–0.06%, depending upon the crystal symmetry and the number of reflections measured. The improved technique also facilitates the location and integration of weak reflections, which are often more difficult to discern amongst the increased background at higher energies. The technique uses a mathematical model of the relative positions of all the detector pixels of the instrument, together with a methodology that establishes a reproducible reference frame and a method for determining the parameters of the instrument detector model. Since all neutron TOF instruments require precise detector calibration for their effective use, it is possible that the method described here may be of use on other instruments where the detector calibration cannot be determined by other means.
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XIA, JUN-QING, HONG LI, GONG-BO ZHAO, and XINMIN ZHANG. "PROBING FOR THE COSMOLOGICAL PARAMETERS WITH PLANCK MEASUREMENT." International Journal of Modern Physics D 17, no. 11 (October 2008): 2025–48. http://dx.doi.org/10.1142/s0218271808013698.
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In this paper we investigate the constraints on the cosmological parameters, especially the equation of state of dynamical dark energy w DE , the inflationary parameters ns, αs and r, the total neutrino mass ∑ mν and the curvature of the universe ΩK, using the simulated data of future Planck measurement. First, we determine the cosmological parameters with the current observations, including ESSENCE (192 samples), Three-Year WMAP (WMAP3), Boomerang-2K2, CBI, VSA, ACBAR, SDSS LRG and 2dFGRS, and then we take the best-fit model as the fiducial model in the ensuing simulations. In the simulations we pay particular attention to the effects of the dynamical dark energy in the determination of the cosmological parameters. For this reason, in order to make our constraints more robust, we have added the simulated SNAP data to our simulations. Using the present data, we find that the Quintom dark energy model is mildly favored, while the ΛCDM model remains a good fit. In the framework of the dynamical dark energy model, the constraints on the inflationary parameters, ∑ mν and ΩK, become weak, compared with the constraints in the ΛCDM model. Intriguingly, we find that the inflationary models with a "blue" tilt, which are excluded about 2σ in the ΛCDM model, are well within the 2σ region with the presence of the dynamics of dark energy. The upper limits of neutrino mass are weakened by a factor of 2 (95% CL) — say, ∑ mν < 1.59 eV and ∑ mν < 1.53 eV for two forms of parametrization of the equation of state of dark energy. The flat universe is a good fit to the current data, namely |ΩK| < 0.03 (95% CL). With the simulated Planck and SNAP data, the dynamical dark energy model and the ΛCDM model might be distinguished at the 4σ confidence level. And the uncertainties of the inflationary parameters, ∑ mν and ΩK, can be reduced significantly in the framework of the dynamical dark energy model. We also constrain the rotation angle Δα, denoting the possible CPT violation, from the simulated Planck and CMBpol data and find that our results are much more stringent than the current constraint and will be used to verify the CPT symmetry with a higher precision.
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Papaioannou, George, Christos Dikaiakos, Akylas Stratigakos, Panos Papageorgiou, and Konstantinos Krommydas. "Testing the Efficiency of Electricity Markets Using a New Composite Measure Based on Nonlinear TS Tools." Energies 12, no. 4 (February 15, 2019): 618. http://dx.doi.org/10.3390/en12040618.
Повний текст джерелаАнотація:
In this paper we examine and compare the efficiency of four European electricity markets (NordPool, Italian, Spanish and Greek) of different microstructure and level of maturity, by testing the weak form of the Efficient Market Hypothesis (EMH). To quantify the level of efficiency deviation of each market from the ‘ideal’ or ‘benchmark market of random walk’, we have constructed a Composite Electricity Market Efficiency Index (EMEI), inspired by similar works on other energy commodities. The proposed index consists of linear and nonlinear components each one measuring a different feature or dimension of the market efficiency such as its complexity, fractality, entropy, long-term memory or correlation, all connected to the associated benchmark values of the Random Walk Process (RWP). The key findings are that overall, all examined electricity markets are inefficient in respect to the weak form of EMH and the less inefficient market, as measured by the EMEI is the NordPool, closely followed by the Spanish market, with the Italian being the third. The most inefficient market is the Greek one. These results are in accordance with the predominant view about the maturity of these markets. This study contributes significantly on improving the research framework in developing consistent and robust tools for efficiency measurement, while the proposed index can be a valuable tool in designing improved guidelines towards enhancing the efficiency of electricity markets.
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Mandal, Partha Pratim, Joel Sarout, and Reza Rezaee. "Specific surface area: A reliable predictor of creep and stress relaxation in gas shales." Leading Edge 40, no. 11 (November 2021): 815–22. http://dx.doi.org/10.1190/tle40110815.1.
Повний текст джерелаАнотація:
In recent years, short-term creep parameters determined in the laboratory from cylindrical gas shale samples subjected to triaxial (in-situ) stress conditions have been used successfully to infer long-term deformation and stress relaxation at the reservoir scale across geologic time scales. Due to the viscoelastic formalism, both the laboratory creep response and field-scale stress relaxation can be modeled with power law functions of time involving the elastic compliance of the shale B, the time-dependence exponent n, and the amount of total strain ∊. Gas shales often exhibit a high specific surface area associated with their high content in clay minerals and/or total organic carbon (TOC). The low-pressure nitrogen adsorption technique can be used advantageously to estimate specific surface area (SN2); i.e., it is a relatively fast and cost-effective measurement conducted on powdered samples of shale material. A robust global empirical correlation between gas shale creep parameters and SN2 emerges from the analysis of laboratory data collected from multiple gas shale formations in Australia (the prospective Goldwyer Formation) and the United States (Barnett, Haynesville, and Eagle Ford formations), and spanning a broad range of clay content, organic matter, maturity, and porosity values. This data set also shows that the summed fractions of clay minerals, TOC, and porosity, the so-called weak phase fraction, correlates nearly as well with primary creep parameters. The weak phase fraction can also be estimated from faster and more cost-effective measurements or from well logs. To evaluate its predictive capacity, the key correlation between SN2 and creep parameters is used in a case study to predict the magnitude of present-day least principal stress Shmin across six depth intervals/lithologic layers in a prolific unconventional shale formation in the northeastern United States. Several Shmin measurements are available for verification, and our approach successfully captures the observed layered variation of stress with depth.
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Sanchez-Comas, Andres, Kåre Synnes, Diego Molina-Estren, Alexander Troncoso-Palacio, and Zhoe Comas-González. "Correlation Analysis of Different Measurement Places of Galvanic Skin Response in Test Groups Facing Pleasant and Unpleasant Stimuli." Sensors 21, no. 12 (June 19, 2021): 4210. http://dx.doi.org/10.3390/s21124210.
Повний текст джерелаАнотація:
The galvanic skin response (GSR; also widely known as electrodermal activity (EDA)) is a signal for stress-related studies. Given the sparsity of studies related to the GSR and the variety of devices, this study was conducted at the Human Health Activity Laboratory (H2AL) with 17 healthy subjects to determine the variability in the detection of changes in the galvanic skin response among a test group with heterogeneous respondents facing pleasant and unpleasant stimuli, correlating the GSR biosignals measured from different body sites. We experimented with the right and left wrist, left fingers, the inner side of the right foot using Shimmer3GSR and Empatica E4 sensors. The results indicated the most promising homogeneous places for measuring the GSR, namely, the left fingers and right foot. The results also suggested that due to a significantly strong correlation among the inner side of the right foot and the left fingers, as well as the moderate correlations with the right and left wrists, the foot may be a suitable place to homogenously measure a GSR signal in a test group. We also discuss some possible causes of weak and negative correlations from anomalies detected in the raw data possibly related to the sensors or the test group, which may be considered to develop robust emotion detection systems based on GRS biosignals.
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Pita, H., G. Zurita, and A. Villarroel. "Software development firmware system for broken rotor bar detection and diagnosis of induction motor through current signature analysis." Journal of Mechanical Engineering and Sciences 14, no. 2 (June 23, 2020): 6917–33. http://dx.doi.org/10.15282/jmes.14.2.2020.30.0542.
Повний текст джерелаАнотація:
The induction motors (IMs) are undoubtedly the most used machines in industries because of the advantages they offer such as simplicity, service continuity and low cost. Due to wear and tear, the motor suffers different types of mechanical and electrical failures. Depending on the criticality of the plant motors, it could be necessary to implement predictive techniques in order to detect the faults before they can cause unnecessary downtime. Therefore, in this paper, the research approach was to develop a low cost measurement system based on a micro controller platform for machine diagnosis. The FRDM K64F developing board was selected as the most suitable for satisfying the system conditions, and it was used to collect induction motor`s current data. In order to validate the accuracy of the developed system, the Frequency Transfer Functions (FRF) of the developed measurement system and the standard system (NI USB-6009) were compare. It showed a flat frequency spectrum from 0 to 1 KHz, with small fluctuations of about 0.25 dB standard deviation. A fully automated test bench was implemented, which allows to perform all the measurement tests with the IMs, and in this case, the detection and diagnosis of broken bars. Around 240 tests were performed with varying loads, different rotation speeds, and with different severity damage levels in the rotor. The data analysis procedure for broken rotor bar detection and motor diagnosis was performed by the Motor Current Signature Analysis (MCSA), FFT and Enveloped Analysis (EA). Finally, the research approach was successfully accomplished, by the team by developing a software firmware measurement ultra-low cost development platform for machine diagnosis. It was also developed a proper antialiasing filter to reduce industrial noise. The effectiveness of the proposed system is detecting a weak fault in a noise signal. It was found out a new consistent and robust parameter called the pole pass frequency (fpsf), which could be used as a diagnosis parameter for detection of broken rotor bars faults, with their damage severity degree. The detected parameter can be found around 2.6 Hz, and it increases in amplitude with increasing damage severity.
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Shirasaki, Masato, Takashi Hamana, Masahiro Takada, Ryuichi Takahashi, and Hironao Miyatake. "Mock galaxy shape catalogues in the Subaru Hyper Suprime-Cam Survey." Monthly Notices of the Royal Astronomical Society 486, no. 1 (March 16, 2019): 52–69. http://dx.doi.org/10.1093/mnras/stz791.
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Abstract We use the full-sky ray-tracing weak lensing simulations to generate 2268 mock catalogues for the Subaru Hyper Suprime-Cam (HSC) survey first-year shear catalogue. Our mock catalogues take into account various effects as in the real data: the survey footprints, inhomogeneous angular distribution of source galaxies, statistical uncertainties in photometric redshift (photo-z) estimate, variations in the lensing weight, and the statistical noise in galaxy shape measurements including both intrinsic shapes and the measurement errors. We then utilize our mock catalogues to evaluate statistical uncertainties expected in measurements of cosmic shear two-point correlations ξ± with tomographic redshift information for the HSC survey. We develop a quasi-analytical formula for the Gaussian sample variance properly taking into account the number of source pairs in the survey footprints. The standard Gaussian formula significantly overestimates or underestimates the mock results by 50 per cent level. We also show that different photo-z catalogues or the six disconnected fields, rather than a consecutive geometry, cause variations in the covariance by ${\sim } 5{{\ \rm per\ cent}}$. The mock catalogues enable us to study the chi-square distribution for ξ±. We find the wider distribution than that naively expected for the distribution with the degrees of freedom of data vector used. Finally, we propose a method to include non-zero multiplicative bias in mock shape catalogue and show that the non-zero multiplicative bias can change the effective shape noise in cosmic shear analyses. Our results suggest an importance of estimating an accurate form of the likelihood function (and therefore the covariance) for robust cosmological parameter inference from the precise measurements.
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Li, Bin Grace, Christopher Adam, Andrew Berg, Peter Montiel, and Stephen O’Connell. "Structural VARs and the Monetary Transmission Mechanism in Low-Income African Countries†." Journal of African Economies 28, no. 4 (April 9, 2019): 455–78. http://dx.doi.org/10.1093/jae/ejz005.
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AbstractStructural Vector Autoregression (SVAR) methods suggest the monetary transmission mechanism may be weak and unreliable in many low-income African countries. But are structural VARs identified via short-run restrictions capable of detecting a transmission mechanism when one exists, under research conditions typical of low-income countries (LICs)? Using a small DSGE as our data-generating process, we assess the impact on VAR-based inference of short data samples, measurement error, high-frequency supply shocks, and other features of the LIC environment. The impact of these features on finite-sample bias appears to be relatively modest when identification is valid—a strong caveat, especially in LICs. Nonetheless many of these features undermine the precision of estimated impulse responses to monetary policy shocks, and cumulatively they suggest that statistically and economically insignificant results can be expected even when the underlying transmission mechanism is strong. These data features not only undermine the efficacy of the SVAR methodology for research and policy-making, but are also severe enough to motivate a continued search for monetary policy rules that are robust to these limitations.
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Dokala, R. K., S. Das, B. Weise, R. Medwal, R. S. Rawat, and S. Thota. "Magnetization reversal, field-induced transitions and H–T phase diagram of Y1−x Ce x CrO3." Journal of Physics: Condensed Matter 34, no. 6 (November 30, 2021): 065801. http://dx.doi.org/10.1088/1361-648x/ac3453.
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Abstract We report a systematic study of the magnetic phase diagram in the H–T plane, negative magnetization (NM), exchange interactions and field-induced spin–flop transitions in the distorted perovskite Y1−x Ce x CrO3. Locked AFM and weak-FM configurations in Γ4(G z , F y , A x ) phase of YCrO3 (S = 3/2 ground state) unlocks into the Γ2 (F z , G y , C x ; F z R , C x R ) phase of the canted AFM and FM structures with the dilute substitution of Ce (x ⩾ 0.05). The asymmetric and symmetric exchange interaction (J AS ∼ 0.11 meV and J S ∼ 0.85 meV) between the trivalent Ce and Cr enable the positive quartic-anisotropy field ( H K 4 ∼ 2.85 × 102 Oe) along with the second order anisotropy field ( H K 2 ∼ 5.93 × 102 Oe). Unlike the pristine YCrO3 compound, the Ce incorporated system exhibits a giant fourth-order anisotropy constant (K 4 = 1.35 × 105 erg/c.c.) due to the asymmetric exchange interaction between the trivalent Ce–Cr which further lifts the free energy of the system and causes lag in the onset of AFM ordering showing the significant thermal hysteresis (ΔT ∼ 10 K) in the field-cooled (FC)-warming measurement protocol as compared to the FC-cooling mode. The H–T phase diagram, mapped from the isothermal magnetization data and differential magnetic susceptibility data with different measurement protocols clearly distinguishes three prominent regions below the T N (∼150 K), viz (i) long-range canted AFM + weak FM phase (Γ4 (G z , F y , A x )), (ii) Γ24 mixed phase and (iii) robust Γ2 (F z , G y , C x ; F z R , C x R ) AFM + FM phases. Tunable spin–flopped transition (∼ 30 kOe), significant negative exchange-bias field (H EB ∼ 2.5 kOe), huge coercive field (H C ∼ 22 kOe) and large NM (ΔM ∼ 280 emu/mole) are the unique characteristic features of the current investigated system.
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Tollaksen, Jeff. "Robust weak measurements on finite samples." Journal of Physics: Conference Series 70 (May 1, 2007): 012015. http://dx.doi.org/10.1088/1742-6596/70/1/012015.
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Akhras, Sami, Marie-Luise Herrlein, Fabian Elgner, Thomas Holzhauser, and Eberhard Hildt. "ZIKV Envelope Domain-Specific Antibodies: Production, Purification and Characterization." Viruses 11, no. 8 (August 13, 2019): 748. http://dx.doi.org/10.3390/v11080748.
Повний текст джерелаАнотація:
Infection with Zika virus (ZIKV) came first to public attention after it was found to be associated with congenital microcephaly during the outbreak in Brazil (2015–2016). Diagnosis of ZIKV suffers from extensive cross-reactivity with other Flaviviruses, which are circulating in many ZIKV epidemic areas. Due to the fatal outcome of ZIKV infection during pregnancy, detailed knowledge about neutralizing and non-neutralizing epitopes is crucial for the development of robust detection systems of protective antibodies. Therefore, additional information about ZIKV immunogenicity and antibody response is required. In this project, we report the production, purification and characterization of six different polyclonal antibodies against ZIKV envelope (E) protein. The produced antibodies bind to isolated ZIKV E protein as well as to the surface of ZIKV particles, interestingly without being potently neutralizing. Surface plasmon resonance measurement showed that these antibodies bind with high affinity to ZIKV E protein. Epitope mapping revealed that the epitopes are distributed among the three ZIKV E domains with seven binding sites. These identified binding sites overlap only partially with the previously described epitopes recognized by neutralizing antibodies, which is in accordance with their lack of potent neutralizing activity. Additionally, these antibodies showed neither cross-reactivity nor potent neutralizing activity against West Nile virus, a related flavivirus. The gained set of data helps to extend our understanding about the distribution of neutralizing and non-/weak-neutralizing epitopes in ZIKV E protein, and provides a rationale for ZIKV vaccine design and development of robust detection assays for neutralizing antibodies.
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Teng, Xichao, Qifeng Yu, Jing Luo, Gang Wang, and Xiaohu Zhang. "Aircraft Pose Estimation Based on Geometry Structure Features and Line Correspondences." Sensors 19, no. 9 (May 9, 2019): 2165. http://dx.doi.org/10.3390/s19092165.
Повний текст джерелаАнотація:
A robust and accurate aircraft pose estimation method is proposed in this paper. The aircraft pose reflects the flight status of the aircraft and accurate pose measurement is of great importance in many aerospace applications. This work aims to establish a universal framework to estimate the aircraft pose based on generic geometry structure features. In our method, line features are extracted to describe the structure of an aircraft in single images and the generic geometry features are exploited to form line groups for aircraft structure recognition. Parallel line clustering is utilized to detect the fuselage reference line and bilateral symmetry property of aircraft provides an important constraint for the extraction of wing edge lines under weak perspective projection. After identifying the main structure of the aircraft, a planes intersection method is used to obtain the 3D pose parameters based on the established line correspondences. Our proposed method can increase the measuring range of binocular vision sensors and has the advantage of not relying on 3D models, cooperative marks or other feature datasets. Experimental results show that our method can obtain reliable and accurate pose information of different types of aircraft.
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de Kleer, Katherine, Zachariah Milby, Carl Schmidt, Maria Camarca, and Michael E. Brown. "The Optical Aurorae of Europa, Ganymede, and Callisto." Planetary Science Journal 4, no. 2 (February 1, 2023): 37. http://dx.doi.org/10.3847/psj/acb53c.
Повний текст джерелаАнотація:
Abstract The tenuous atmospheres of the Galilean satellites are sourced from their surfaces and produced by a combination of plasma-surface interactions and thermal processes. Even though they are thin, these atmospheres can be studied via their auroral emissions, and most work to date has focused on their aurorae at UV wavelengths. Here we present the first detections of the optical aurorae of Ganymede and Callisto, as well as detections of new optical auroral lines at Europa, based on observations of the targets over 10 Jupiter eclipses from 1998 to 2021 with Keck/HIRES. We present measurements of O i emission at 6300/6364, 5577, 7774, and 8446 Å and place upper limits on hydrogen at 6563 Å. These constitute the first detections of emissions at 7774 and 8446 Å at a planetary body other than Earth. The simultaneous measurement of multiple emission lines provides robust constraints on atmospheric composition. We find that the eclipse atmospheres of Europa and Ganymede are composed predominantly of O2, with average column densities of (4.1 ± 0.1) × 1014 cm−2 and (4.7 ± 0.1) × 1014 cm−2, respectively. We find weak evidence for H2O in Europa's bulk atmosphere at an H2O/O2 ratio of ∼0.25, and place only an upper limit on H2O in Ganymede's bulk atmosphere, corresponding to H2O/O2 < 0.6. The column density of O2 derived for Callisto is (4.0 ± 0.9) × 1015 cm−2 for an assumed electron density of 0.15 cm−3, but electron properties at Callisto's orbit are very poorly constrained.
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K. Sejjaaka, Samuel, and Twaha K. Kaawaase. "Professionalism, rewards, job satisfaction and organizational commitment amongst accounting professionals in Uganda." Journal of Accounting in Emerging Economies 4, no. 2 (July 1, 2014): 134–57. http://dx.doi.org/10.1108/jaee-01-2012-0003.
Повний текст джерелаАнотація:
Purpose – The purpose of this paper is to examine the extent to which the constructs of professionalism (Hall, 1968), rewards (Bartol, 1979) and job satisfaction (Stamps and Piedmonte, 1986; Hampton and Hampton, 2004) can be used as valid predictors of organizational commitment (Porter et al., 1974) in an emerging economy context. Design/methodology/approach – Using pre-existing scales for these constructs, the authors collected data from 277 ICPAU licensees’ and carried out a factor analysis to examine their validity. Given the relevance of the organizational-professional conflict (OPC) debate to performance in public and private sector organizations, the authors use ANOVA to assess whether there are significant differences between CPAs in the private and public sectors. We also develop a structural equation model to assess the extent to which organizational commitment can be explained by professionalism, rewards and job satisfaction. Findings – The findings show that the four scales can be used as valid measures in an emerging market environment, albeit with some modifications. The correlations between the study variables are significant (p<0.01) but weak. There are also no significant differences between the scores of private and public sector Certified Public Accountant (CPAs) on professionalism, rewards and organizational commitment. However, there is significantly lower job satisfaction amongst CPAs employed in the public sector. The authors also find that job satisfaction is the best predictor of organizational commitment. Professionalism and rewards are weak predictors of organizational commitment. The fitted model shows that there is a weak fit between organizational commitment and professionalism, rewards and job satisfaction (GFI=0.86, RMSEA=0.086). Originality/value – The authors modify the extant measurement scales for use in emerging market conditions and show that with some adjustment, they are robust measures of the study variables. The paper also extends the organizational commitment (OC) debate to emerging market conditions and shows that rewards on their own are not enough to ensure organizational commitment amongst professionals. It is important to improve job satisfaction through more enriching work experience.
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Aguilera, Felipe, Susana Layana, Felipe Rojas, Pilar Arratia, Thomas C. Wilkes, Cristóbal González, Manuel Inostroza, Andrew J. S. McGonigle, Tom D. Pering, and Gabriel Ureta. "First Measurements of Gas Flux with a Low-Cost Smartphone Sensor-Based UV Camera on the Volcanoes of Northern Chile." Remote Sensing 12, no. 13 (July 2, 2020): 2122. http://dx.doi.org/10.3390/rs12132122.
Повний текст джерелаАнотація:
UV cameras have been used for over a decade in order to remotely sense SO2 emission rates from active volcanoes, and to thereby enhance our understanding of processes related to active and passive degassing. Whilst SO2 column density retrievals can be more accurate/sophisticated using alternative techniques (e.g., Differential Optical Absorption Spectrometer (DOAS), Correlation Spectrometer (COSPEC)), due to their higher spectral resolutions, UV cameras provide the advantage of high time-resolution emission rates, a much greater spatial resolution, and the ability to simultaneously retrieve plume speeds. Nevertheless, the relatively high costs have limited their uptake to a limited number of research groups and volcanic observatories across the planet. One recent intervention in this regard has been the introduction of the PiCam UV camera, which has considerably lowered instrumental cost. Here we present the first data obtained with the PiCam system from seven persistently degassing volcanoes in northern Chile, demonstrating robust field operation in challenging conditions and over an extended period of time, hence adding credence to the potential of these units for more widespread dissemination to the international volcanic gas measurement community. Small and weak plumes, as well as strongly degassing plumes were measured at distances ranging 0.6–10.8 km from the sources, resulting in a wide range of SO2 emission rates, varying from 3.8 ± 1.8 to 361 ± 31.6 td−1. Our acquired data are discussed with reference to previously reported emission rates from other ground-based remotely sensed techniques at the same volcanoes, in particular considering: resolution of single plume emissions in multi-plume volcanoes, light dilution, plume geometry, seasonal effects, and the applied plume speed measurement methodology. The main internal/external factors that influence positive/negative PiCam measurements include camera shake, light dilution, and the performance of the OpenCV and control points post processing methods. A simple reprocessing method is presented in order to correct the camera shake. Finally, volcanoes were separated into two distinct groups: low and moderate SO2 emission rates systems. These groups correlate positively with their volcanological characteristics, especially with the fluid compositions from fumaroles.
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Park, Hyungwon John, Jeffrey S. Reid, Livia S. Freire, Christopher Jackson, and David H. Richter. "In situ particle sampling relationships to surface and turbulent fluxes using large eddy simulations with Lagrangian particles." Atmospheric Measurement Techniques 15, no. 23 (December 13, 2022): 7171–94. http://dx.doi.org/10.5194/amt-15-7171-2022.
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Abstract. Source functions for mechanically driven coarse-mode sea spray and dust aerosol particles span orders of magnitude owing to a combination of physical sensitivity in the system and large measurement uncertainty. Outside special idealized settings (such as wind tunnels), aerosol particle fluxes are largely inferred from a host of methods, including local eddy correlation, gradient methods, and dry deposition methods. In all of these methods, it is difficult to relate point measurements from towers, ships, or aircraft to a general representative flux of aerosol particles. This difficulty is from the particles' inhomogeneous distribution due to multiple spatiotemporal scales of an evolving marine environment. We hypothesize that the current representation of a point in situ measurement of sea spray or dust particles is a likely contributor to the unrealistic range of flux and concentration outcomes in the literature. This paper aims to help the interpretation of field data: we conduct a series of high-resolution, cloud-free large eddy simulations (LESs) with Lagrangian particles to better understand the temporal evolution and volumetric variability of coarse- to giant-mode marine aerosol particles and their relationship to turbulent transport. The study begins by describing the Lagrangian LES model framework and simulates flux measurements that were made using numerical analogs to field practices such as the eddy covariance method. Using these methods, turbulent flux sampling is quantified based on key features such as coherent structures within the marine atmospheric boundary layer (MABL) and aerosol particle size. We show that for an unstable atmospheric stability, the MABL exhibits large coherent eddy structures, and as a consequence, the flux measurement outcome becomes strongly tied to spatial length scales and relative sampling of crosswise and streamwise sampling. For example, through the use of ogive curves, a given sampling duration of a fixed numerical sampling instrument is found to capture 80 % of the aerosol flux given a sampling rate of zf/w∗∼ 0.2, whereas a spanwise moving instrument results in a 95 % capture. These coherent structures and other canonical features contribute to the lack of convergence to the true aerosol vertical flux at any height. As expected, sampling all of the flow features results in a statistically robust flux signal. Analysis of a neutral boundary layer configuration results in a lower predictive range due to weak or no vertical roll structures compared to the unstable boundary layer setting. Finally, we take the results of each approach and compare their surface flux variability: a baseline metric used in regional and global aerosol models.
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Ocio, D., T. Beskeen, and K. Smart. "Fully distributed hydrological modelling for catchment-wide hydrological data verification." Hydrology Research 50, no. 6 (June 3, 2019): 1520–34. http://dx.doi.org/10.2166/nh.2019.006.
Повний текст джерелаАнотація:
Abstract Hydrological data scarcity and uncertainty is a fundamental challenge in hydrology, particularly in places with weak or declining investment in hydrometric networks. It is well established that fully distributed hydrological models can provide robust estimation of flows at ungauged locations, through local calibration and regionalisation using spatial datasets of physical properties. Even in situations where data are abundant, the existence of inconsistent information is not uncommon. The measurement, estimation or interpolation of rainfall, potential evapotranspiration and flow as well as the difficulty in monitoring artificial influences are all sources of potential inconsistency. Less studied but as important, distributed hydrological models, given their capability of capturing both the temporal and spatial dimensions of the water balance and runoff generation, are suitable tools to identify potential deficiencies in, and reliability of, input data. Three heavily modified catchments in the East of England such as the Ely Ouse, the Witham, and the Black Sluice have been considered, all of which have issues of data scarcity and uncertainty. This paper demonstrates not only the benefits of fully distributed modelling in addressing data availability issues but also in its use as a catchment-wide data validation tool that serves to maximise the potential of limited data and contributes to improved basin representation.