The use of non-contact scanning equipment in metrology and in dimensional and geometric inspection applications is increasing due to its ease of use, the speed and density of scans, and the current ...costs. In fact, these technologies are becoming increasingly dominant in the industrial environment, thus moving from reverse engineering applications to metrological applications. However, this planned transfer requires actions to ensure the achievable accuracy by providing traceability of measurements. In the present study, a comparison between the devices is carried out and a specific standard artefact is designed, equipped with multiple ceramic optically friendly entities, and allowing a wide variety of geometric dimensioning and tolerancing (GD&T). Four different 3D scanning sensors are used in the experimentation. Three of them are based on laser triangulation, and the fourth is a structured blue light sensor (fringe pattern projection). The standard artefact is calibrated with a high accuracy, using a coordinate measuring machine (CMM) and probing sensors. With this CMM, reference values of multiple predefined GD&T are obtained. The evaluation methodology maximises the accuracy of each device in measuring the dimensions of the artefact due to the good dimensional (milling and turning), surface (control of machining variables), and the dimensional and spatial distribution characteristics. The procedure also includes the same treatment of the captured point clouds (trimming, filtering, and best-fit algorithm, etc.) in each of the four 3D scanning sensors considered. From this process, very reliable measurements of the maximum achievable accuracy of each device (deviations from the CMM measurements) are finally obtained, and a multi-characteristic comparison between the four sensors is performed, also with high reliability.
In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and ...magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources. The paper provides a detailed description of: (1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload; (2) the elements and functions of the mission, from the spacecraft to the ground segment.
Understanding the basin-scale hydrology and the spatiotemporal distribution of regional precipitation requires high precision, as well as high-resolution precipitation data. We have made an attempt ...to develop an Integrated Downscaling and Calibration (IDAC) framework to generate high-resolution (1 km × 1 km) gridded precipitation data. Traditionally, GWR (Geographical weighted regression) model has widely been applied to generate high-resolution precipitation data for regional scales. The GWR model generally assumes a spatially varied relationships between precipitation and its associated environmental variables, however, the relationships need to remain constant (fixed) for some variables over space. In this study, a Mixed Geographically Weighted Regression (MGWR) model, capable of dealing with the fixed and spatially varied environmental variables, is proposed to downscale the Original-TRMM precipitation data from a coarse resolution (0.25o × 0.25o) to a high-resolution (1 km × 1 km) for the period of 2000–2018 over the Upper Indus Basin (UIB). Additionally, accuracy of the downscaled precipitation data was further improved by merging it with the recorded data from rain gauge stations (RGS) using two calibration approaches such as Geographical Ratio Analysis (GRA) and Geographical Difference Analysis (GDA). We found MGWR to perform better given its higher R2 and lower RMSE and bias values (R2 = 0.96; RMSE = 56.01 mm, bias = 0.014) in comparison to the GWR model (R2 = 0.95; RMSE = 60.76 mm, bias = 0.094). It was observed that the GDA and GRA calibrated-downscaled precipitation datasets were superior to the Original-TRMM, yet GRA outperformed GDA. Annual precipitation from downscaled and calibrated-downscaled datasets was further temporally downscaled to obtain high-resolution monthly and daily precipitations. The results revealed that the monthly-downscaled precipitation (R2 = 0.82, bias = −0.02 and RMSE = 11.93 mm/month) and the calibrated-downscaled (R2 = 0.89, bias = −0.006 and RMSE = 9.19 mm/month) series outperformed the Original-TRMM (R2 = 0.72, bias = 0.14 and RMSE = 19.8 mm/month) as compared to the RGS observations. The results of daily calibrated-downscaled precipitation (R2 = 0.79, bias = 0.001 and RMSE = 1.7 mm/day) were better than the Original-TRMM (R2 = 0.64, bias = − 0.12 and RMSE = 6.82 mm/day). In general, the proposed IDAC approach is suitable for retrieving high spatial resolution gridded data for annual, monthly, and daily time scales over the UIB with varying climate and complex topography.
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•GVT offers a promising method for filtering out both spatially varying and constant relations.•Newly proposed MGWR model performed better than the traditional GWR model.•GRA perform better than the GDA during calibration process.•Downscaled precipitation at 1 km, demonstrated better accuracy than original-TRMM.•IDAC approach is suitable to retrieve high-resolution gridded precipitation data.
Coherence is a fundamental resource in quantum information processing, which can be certified by a coherence witness. Due to the imperfection of measurement devices, a conventional coherence witness ...may lead to fallacious results. We show that the conventional witness could mistake an incoherent state as a state with coherence due to the inaccurate settings of measurement bases. In order to make the witness result reliable, we propose a measurement-device-independent coherence witness scheme without any assumptions on the measurement settings. We introduce the decoy-state method to significantly increase the capability of recognizing states with coherence. Furthermore, we experimentally demonstrate the scheme in a time-bin encoding optical system.
The objective of the present research was to evaluate the level of motor coordination in 9-year-old infants belonging to sports training schools in Bogotá and Chía-Cundinamarca in a post-confinement ...context by means of the 3JS test in relation to gender, sociodemographic context, sport, confinement training and days of training. The study included 307 infants, of which: 187 were male and 120 were female. Likewise, they were grouped by sport: soccer n:113, skating n:91, basketball n:52 and tennis n:51 and, finally, by sociodemographic context 102 were evaluated in Chia-Cundinamarca and 205 in Bogotá. The study has a quantitative approach, descriptive-transversal type and with a non-probabilistic sampling. The statistical treatment was carried out using the statistical software ® version 4.1.0. The results indicate that the significant differences were established in response to gender p=0.00 better in male infants, sociodemographic context p=0.04 better in Bogotá, days of training p=0.006 better in equal or greater than four days of weekly training, training in confinement during Covid-19 p=0.02 better in those who trained and sport p=0.00 evidencing significant differences between them, having as reference soccer as the highest and tennis the lowest level correspondingly. These findings show that normal levels of motor coordination were found for all the infants evaluated according to the intervals proposed by the 3JS test, likewise, the differences were established in turn, between locomotor coordination and object control coordination according to the variables object of this study.
El objetivo de la presente investigación fue evaluar el nivel de coordinación motriz en infantes de 9 años pertenecientes a escuelas de formación deportivas en Bogotá y Chía-Cundinamarca en un contexto de post confinamiento por medio del test 3JS con relación al género, contexto sociodemográfico, deporte, entrenamiento en confinamiento y días de entrenamiento. El estudio incluyó 307 infantes, de los cuales: 187 correspondieron al género masculino y 120 al femenino. Asimismo, fueron agrupados por deporte: fútbol n:113, patinaje n:91, baloncesto n:52 y tenis n:51 y, finalmente, por contexto sociodemográfico 102 fueron evaluados en Chía-Cundinamarca y 205 en Bogotá. El estudio es de enfoque cuantitativo, de tipo descriptivo-transversal y con un muestreo no probabilístico. El tratamiento estadístico fue realizado mediante el software estadístico ® versión 4.1.0. Los resultados indican que, las diferencias significativas se establecieron en respuesta al género p=0.00 mejor en infantes masculinos, contexto sociodemográfico p=0.04 mejor en Bogotá, días de entrenamiento p=0.006 mejor en igual o mayor a cuatro días de entrenamiento semanal, entrenamiento en confinamiento durante la Covid-19 p=0.02 mejor en los que entrenaron y deporte p=0.00 evidenciando diferencias significativas entre ellas, teniendo como referencia a fútbol como la de mayor y patinaje la de menor nivel correspondientemente. Estos hallazgos evidencian que se encontraron niveles normales de coordinación motriz para todos los infantes evaluados según los intervalos propuestos por el test 3JS, asimismo, las diferencias se establecieron a su vez, entre la coordinación locomotriz y coordinación control de objetos según las variables objeto de este estudio.
Billions of animals cross the globe each year during seasonal migrations, but efforts to monitor them are hampered by the unpredictability of their movements. We developed a bird migration forecast ...system at a continental scale by leveraging 23 years of spring observations to identify associations between atmospheric conditions and bird migration intensity. Our models explained up to 81% of variation in migration intensity across the United States at altitudes of 0 to 3000 meters, and performance remained high in forecasting events 1 to 7 days in advance (62 to 76% of variation was explained). Avian migratory movements across the United States likely exceed 500 million individuals per night during peak passage. Bird migration forecasts will reduce collisions with buildings, airplanes, and wind turbines; inform a variety of monitoring efforts; and engage the public.
This letter presents a new optical fiber structure with the capability of measuring nano-displacement. This device is composed by a cleaved fiber and a drop-shaped microstructure that is connected to ...the fiber cladding. This optical structure is responsible for the light beam division and the formation of new optical paths. The operation mode consists of the Vernier effect that allows achieving higher sensitivity than the currently sensors. During the experimental execution, displacement sensitivities of 1.05 ± 0.01 nm/<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, 15.1 ± 0.1 nm/<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, 24.7 ± 0.3 nm/<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> and 28.3 ± 0.3 nm/<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, were achieved for the carrier, the fundamental of the envelope, the first harmonic and the second harmonic, respectively. The M-factor of 27 was attained, allowing a minimum resolution of 0.7 nm. In addition to displacement sensing, the proposed optical sensor can be used as a cantilever enabling non-evasive measurements.
Gaussian phasor measurement unit (PMU) measurement error has been assumed for many power system applications, such as state estimation, oscillatory modes monitoring, voltage stability analysis, to ...cite a few. This letter proposes a simple yet effective approach to assess this assumption by using the stability property of a probability distribution and the concept of redundant measurement. Extensive results using field PMU data from WECC system reveal that the Gaussian assumption is questionable.
This paper provides a comprehensive review of distribution system state estimation in terms of basic definition, different methods, and their application. In the last few years, the operation of ...distribution networks has been influenced by the installation of distributed generations. In order to control and manage an active distribution network’s performance, distribution system state estimation methods are introduced. A transmission system state estimation cannot be used directly in distribution networks since transmission and distribution networks are different due to topology configuration, the number of buses, line parameters, and the number of measurement instruments. So, the proper state estimation algorithms should be proposed according to the main distribution network features. Accuracy, computational efficiency, and practical implications should be considered in the designing of distribution state estimation techniques since technical issues and wrong decisions could emerge in the control center by inaccurate distribution state estimation results. In this study, conventional techniques are reviewed and compared with data-driven methods in order to highlight the pros and cons of different techniques. Furthermore, the integrated distribution state estimation methods are compared with the distributed approaches, and the different criteria, including the level of area overlapping execution time and computing architecture, are elaborated. Moreover, mathematical problem formulation and different measuring methods are discussed.
Accurately quantifying unsteady methane venting from key oil and gas sector sources such as storage tanks and well casing vents is a critical challenge. Recently, we presented an optical sensor to ...meet this need that combines volume fraction and Doppler shift measurements using wavelength modulation spectroscopy with 2f harmonic detection to quantify mass flux of methane through a vent line. This paper extends the previous effort through a methodical component-by-component investigation of potential sources of thermally-induced measurement drift to guide the design of an updated sensor. Test data were analyzed using an innovative signal processing technique that permitted quantification of background wavelength modulation spectroscopy signal drift linked to specific components, and the results were successfully used to design a drift-resistant sensor. In the updated sensor, background signal strength was reduced, and stability improved, such that the empirical methane-fraction dependent velocity correction necessary in the original sensor was no longer required. The revised sensor improves previously reported measurement uncertainties on flow velocity from 0.15 to 0.10 m/s, while markedly reducing thermally-induced velocity drift from 0.44 m/s/K to 0.015 m/s/K. In the most general and challenging application, where both flow velocity and methane fraction are independently varying, the updated design reduces the methane mass flow rate uncertainty by more than a factor of six, from ±2.55 kg/h to ±0.40 kg/h. This new design also maintains the intrinsic safety of the original sensor and is ideally suited for unsteady methane vent measurements within hazardous locations typical of oil and gas facilities.
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