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[IEEE 2018 IEEE ANDESCON - Santiago de Cali, Colombia (2018.8.22-2018.8.24)] 2018 IEEE ANDESCON - Development of a Low-Cost Pulse Oximeter Simulator for Educational Purposes
摘要： Medical instrumentation devices are crucial to determine health conditions in humans. Teaching biomedical instrumentation requires a perfect combination of practice and theory. Therefore, the use of physiological signals simulators such as a %SpO2 becomes important as a teaching strategy. The objective of this project is to develop and implement an oxygen saturation simulator, for use in the biomedical instrumentation courses. The development process began by establishing the requirements of the simulator and designing a graphical user interface to control the simulator parameters. Subsequently, a circuit capable of materializing the simulated signals from the interface was developed, together with a probe or artificial finger that was to be introduced inside the objective pulse oximeter. Finally, the systems were integrated into the simulator
关键词： simulation,low cost,Pulse oximetry,biomedical instrumentation,education
更新于2025-09-23 15:23:52
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Statistical characterisation of polychromatic absolute and differential squared visibilities obtained from AMBER/VLTI instrument
摘要： Context. In optical interferometry, the visibility squared moduli are generally assumed to follow a Gaussian distribution and to be independent of each other. A quantitative analysis of the relevance of such assumptions is important to help improving the exploitation of existing and upcoming multi-wavelength interferometric instruments. Aims. The aims of this study are to analyse the statistical behaviour of both the absolute and the colour-differential squared visibilities: distribution laws, correlations and cross-correlations between different baselines. Methods. We use observations of stellar calibrators obtained with the AMBER instrument on the Very Large Telescope Interferometer (VLTI) in different instrumental and observing configurations, from which we extract the frame-by-frame transfer function. Statistical hypotheses tests and diagnostics are then systematically applied. We also compute the same analysis after correcting the instantaneous squared visibilities from the piston and jitter chromatic effects, using a low-order fit subtraction. Results. For both absolute and differential squared visibilities and under all instrumental and observing conditions, we find a better fit for the Student distribution than for the Gaussian, log-normal, and Cauchy distributions. We find and analyse clear correlation effects caused by atmospheric perturbations. The differential squared visibilities allow us to keep a larger fraction of data with respect to selected absolute squared visibilities and thus benefit from reduced temporal dispersion, while their distribution is more clearly characterised. Conclusions. The frame selection based on the criterion of a fixed signal-to-noise value might result in either a biased sample of frames or one with severe selection. Instead, we suggest an adaptive frame selection procedure based on the stability of the modes of the observed squared visibility distributions. In addition, taking into account the correlations effects between measured squared visibilities should help improve the models used in inverse problems and, thus, the accuracy of model fits and image reconstruction results. Finally, our results indicate that re-scaled differential squared visibilities usually constitute a valuable alternative estimator of squared visibility.
关键词： instrumentation: interferometers,methods: statistical,infrared: stars
更新于2025-09-23 15:23:52
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High resolution mesospheric sodium properties for adaptive optics applications
摘要： Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims. It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods. We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results. The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a specified fraction of the returned sodium light. We find a mean value of 13.1 ± 0.3 km for the range containing 95% of the photons, with a maximum width of 21 km. The temporal power spectral density of fluctuations of the centroid altitude is well described by a power law having an index that ranges from ?1.6 to ?2.3 with a mean value of ?1.87 ± 0.02. This is significantly steeper than the value of ?5/3 that would be expected if the dynamics were dominated by Kolmogorov turbulence, indicating that other factors such as gravity waves play an important role. The amplitude of the power spectrum has a mean value of 34+6?5 m2 Hz?1 at a frequency of 1 Hz, but ranges over two orders of magnitude. The annual means of the index and amplitude show a variation that is well beyond the calculated error range. Long-term global weather patterns may be responsible for this effect.
关键词： site testing,atmospheric effects,methods: observational,instrumentation: adaptive optics
更新于2025-09-23 15:23:52
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Optical Sensing of Broadband RF Magnetic Field Using a Micrometer-Sized Diamond
摘要： High-resolution ?eld imaging with minimized invasiveness is of growing interest with the development of radio frequency (RF) integrated circuits and planar antenna characterization. In this paper, we propose an optical broadband sensor with static offset magnetic ?eld using a diamond crystal that contains an ensemble of nitrogen-vacancy (NV) centers. The spatial resolution of micrometer scale is demonstrated by using a diamond crystal of this size. This technique is based on the modulation of ?uorescence emitting by NV center under green laser excitation, by an off-axis magnetic ?eld at radio frequencies. We demonstrate experimentally the detection of an RF magnetic ?eld, with minimum measurable amplitude on the order of 0.1 Gauss, which is limited by the noise ?oor of the avalanche photodetector. The sensitivity can be further improved by noise suppression in optics. The bandwidth of the sensor is measured to be 15 MHz.
关键词： near-?eld imaging,magnetic ?eld,magnetic resonance,Instrumentation and measurement,real time,laser
更新于2025-09-23 15:23:52
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Estimating the mirror seeing for a large optical telescope with a numerical method
摘要： It is widely accepted that mirror seeing is caused by turbulent fluctuations in the index of air refraction in the vicinity of a telescope mirror. Computational Fluid Dynamics (CFD) is a useful tool to evaluate the effects of mirror seeing. In this paper, we present a numerical method to estimate the mirror seeing for a large optical telescope (～ 4 m) in cases of natural convection with the ANSYS ICEPAK software. We get the FWHM of the image for different inclination angles (i) of the mirror and different temperature differences (?T ) between the mirror and ambient air. Our results show that the mirror seeing depends very weakly on i, which agrees with observational data from the Canada-France-Hawaii Telescope. The numerical model can be used to estimate mirror seeing in the case of natural convection although with some limitations. We can determine ?T for thermal control of the primary mirror according to the simulation, empirical data and site seeing.
关键词： astronomical instrumentation,methods: numerical,telescopes
更新于2025-09-23 15:23:52
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Upgraded photometric system on the 85-cm telescope at Xinglong station
摘要： The 85-cm telescope at Xinglong station is a prime focus system that operates well with high science outputs. The telescope has been upgraded since 2014 with a new corrector, and new filters and camera, which are provided by Beijing Normal University. The filter set is the Johnson-Cousins UBVRI system. We report the test results of the new system including bias, dark current, linearity, gain and readout noise of the CCD camera. Then we derive accurate instrumental calibration coefficients in UBVRI bands with Landolt standard stars during photometric nights. Finally, we give the limiting magnitudes with various exposure times and signal-to-noise ratios for observers as references.
关键词： CCD photometry,instrumentation,telescope
更新于2025-09-23 15:23:52
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Characterizing daytime wind profiles with the wide-field Shack–Hartmann wavefront sensor
摘要： Knowledge of the vertical spatio-temporal distribution of the wind speed and direction is essential for optimizing the performance of adaptive optics systems. An extension of SLODAR (slope detection and ranging) can be used for wind profiling by tracking the time-delayed cross-correlation peaks obtained from the slope of the Shack–Hartmann wavefront sensor. This wind-profiling method works well in situations where the cross-correlation peaks can be individualized, but in many cases the isolated cross-correlation peaks for each turbulent layer are difficult to find in the 2D cross-correlation maps, which can result in difficulties when estimating the wind profiles. To address this problem, we propose a method to measure the wind speed and direction of each layer. The method distinguishes isolated peaks more easily and is valid for multiple peaks, even for a weak response. Instead of tracking peaks in 2D cross-correlation maps, the proposed method traces a series of cross-correlation peaks in the curves of 1D slices through the maps from different directions, and finally determines the wind speed and direction according to the frozen-flow hypothesis. This method is verified with simulations, in which the input wind profiles are recovered accurately. Furthermore, this method is applied to 47 data sequences from the 1-m New Vacuum Solar Telescope at Fuxian Solar Observatory. The wind profiles are estimated from the ground up to 12 km, and the experimental results show that all layers move with a relatively low speed.
关键词： Sun: granulation,atmospheric effects,instrumentation: adaptive optics
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Houston, TX (2018.5.14-2018.5.17)] 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Multi-core cable fault diagnosis using cluster time-frequency domain reflectometry
摘要： Guaranteeing the integrity and functionality of the control and instrumentation (C&I) cable system is essential in ensuring safe nuclear power plant (NPP) operation. When a fault occurs in a multi-core cable, it not only affects the signals of faulty lines but in fact, disturbs the rest as well due to crosstalk and noise interference. Therefore, this results in C&I signal errors in NPP operation and further leads to a rise in concern regarding the NPP operation. Thus, it is necessary for diagnostic technologies of multi-core C&I cables to classify the faulty line and detect the fault to assure the safety and reliability of NPP operation. We propose a diagnostic method that detects the fault location and faulty line in multi-core C&I cable using a clustering algorithm based on TFDR results. The faulty line detection clustering algorithm uses TFDR cross-correlation and phase synchrony results as input feature data altogether which can detect the faulty line and identify the fault point successfully. The proposed clustering algorithm is verified by experiments with two possible fault scenarios in NPP operation.
关键词： fault diagnosis,reflectometry,control and instrumentation cable,K-means clustering,crosstalk,time-frequency analysis
更新于2025-09-23 15:23:52
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Fast global orbit feedback system in PLS-II
摘要： The transverse position of the electron beam in the Pohang Light Source-II is stabilized by the global orbit feedback system. A slow orbit feedback system has been operating at 2 Hz, and a fast orbit feedback (FOFB) system at 813 Hz was installed recently. This FOFB system consists of 96 electron-beam-position monitors, 48 horizontal fast correctors, 48 vertical fast correctors and Versa Module Europa bus control system. We present the design and implementation of the FOFB system and its test result. Simulation analysis is presented and future improvements are suggested.
关键词： Instrumentation for particle accelerators and storage rings - high energy (linear accelerators, synchrotrons),Instrumentation for synchrotron radiation accelerators,Accelerator Subsystems and Technologies
更新于2025-09-23 15:22:29
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Magnetic Shielding of Soft Protons in Future X-Ray Telescopes: The Case of the ATHENA Wide Field Imager
摘要： Both interplanetary space and Earth’s magnetosphere are populated by low-energy (～300 keV) protons that are potentially able to scatter on the reflecting surface of the Wolter-I optics of X-ray focusing telescopes and reach the focal plane. This phenomenon, depending on the X-ray instrumentation, can dramatically increase the background level, reducing the sensitivity or, in the most extreme cases, compromising the observation itself. The use of a magnetic diverter, deflecting protons away from the field of view, requires a detailed characterization of their angular and energy distribution when exiting the mirror. We present the first end-to-end Geant4 simulation of proton scattering by X-ray optics and the consequent interaction with the diverter field and the X-ray detector assembly, selecting the ATHENA Wide Field Imager as a case study for the evaluation of the residual, soft-proton-induced background. We find that in the absence of a magnetic diverter, protons are indeed funneled toward the focal plane, with a focused non-X-ray background well above the level required by ATHENA science objectives (5 × 10?4 counts cm?2 s?1 keV?1), for all the plasma regimes encountered in both L1 and L2 orbits. These results set the proton diverter as a mandatory shielding system on board the ATHENA mission and all high throughput X-ray telescopes operating in the interplanetary space. For a magnetic field computed to deflect 99% of the protons that would otherwise reach the WFI, Geant4 simulations show that this configuration, in the assumption of a uniform field, would efficiently shield the focal plane, yielding a residual background level of the order or below the requirement.
关键词： telescopes,instrumentation: miscellaneous
更新于2025-09-23 15:22:29