High performance with high accuracy laboratory

ln order to obtain high performance with high accuracy in the so lution of scientific computational problems, a computational tool has been developed, called High Performance with High Accuracy Labora tory. ln this paper we describe initially the high performance and then the high accuracy and the interval mathematics. After that , the tool is described, including two environments in which it has been developed, that is, the Cray Supercomputer vector environment and the paral lel environment based on Transputers. The description summarizes the modules, the basic interval library, the high accuracy arithmetic kernel, the interval applied modules, especially the selint.p library. Finally, there are some comments about the performanc

Solid-state interferometric interrogator and multiplexer for high-speed dynamic and absolute FBG wavelength measurement

We present a solid-state FBG array interrogator and multiplexer capable of determining absolute FBG wavelengths and of providing high-speed, high-resolution static and dynamic measurements. Using a described procedure, deployable on multiplexing passive-interferometric schemes, the system is able to determine initial sensor wavelengths and thereafter track wavelength changes with interferometric resolution. The scheme allows high-resolution interrogation of FBG sensor arrays to be applied to many industrial applications, where previously the lack of combined absolute and quasi-static wavelength measurement precluded the use of interferometric techniques. Using a preliminary laboratory embodiment, we demonstrate a wavelength determination accuracy of <0.3 nm and a measurement resolution of 10 fm/√Hz, and propose pathways to improved performance and miniaturisation

Focal plane wavefront sensor achromatization : The multireference self-coherent camera

High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation and high flux ratio. Recently, optimized instruments like SPHERE and GPI were installed on 8m-class telescopes. These will probe young gazeous exoplanets at large separations (~1au) but, because of uncalibrated aberrations that induce speckles in the coronagraphic images, they are not able to detect older and fainter planets. There are always aberrations that are slowly evolving in time. They create quasi-static speckles that cannot be calibrated a posteriori with sufficient accuracy. An active correction of these speckles is thus needed to reach very high contrast levels (>1e7). This requires a focal plane wavefront sensor. Our team proposed the SCC, the performance of which was demonstrated in the laboratory. As for all focal plane wavefront sensors, these are sensitive to chromatism and we propose an upgrade that mitigates the chromatism effects. First, we recall the principle of the SCC and we explain its limitations in polychromatic light. Then, we present and numerically study two upgrades to mitigate chromatism effects: the optical path difference method and the multireference self-coherent camera. Finally, we present laboratory tests of the latter solution. We demonstrate in the laboratory that the MRSCC camera can be used as a focal plane wavefront sensor in polychromatic light using an 80 nm bandwidth at 640 nm. We reach a performance that is close to the chromatic limitations of our bench: contrast of 4.5e-8 between 5 and 17 lambda/D. The performance of the MRSCC is promising for future high-contrast imaging instruments that aim to actively minimize the speckle intensity so as to detect and spectrally characterize faint old or light gaseous planets.Comment: 14 pages, 20 figure

Evidence-based clinical engineering : machine learning algorithms for prediction of defibrillator performance

Poorly regulated and insufficiently supervised medical devices (MDs) carry high risk of performance accuracy and safety deviations effecting the clinical accuracy and efficiency of patient diagnosis and treatments. Even with the increase of technological sophistication of devices, incidents involving defibrillator malfunction are unfortunately not rare. To address this, we have developed an automated system based on machine learning algorithms that can predict performance of defibrillators and possible performance failures of the device which can affect performance. To develop an automated system, with high accuracy, overall dataset containing safety and performance measurements data was acquired from periodical safety and performance inspections of 1221 defibrillator. These inspections were carried out in period 2015–2017 in private and public healthcare institutions in Bosnia and Herzegovina by ISO 17,020 accredited laboratory. Out of overall number of samples, 974 of them were used during system development and 247 samples were used for subsequent validation of system performance. During system development, 5 different machine learning algorithms were used, and resulting systems were compared by obtained performance

Verification of examination procedures in clinical laboratory for imprecision, trueness and diagnostic accuracy according to ISO 15189:2012: a pragmatic approach

Background The International Standard ISO 15189 is recognized as a valuable guide in ensuring high quality clinical laboratory services and promoting the harmonization of accreditation programmes in laboratory medicine. Examination procedures must be verified in order to guarantee that their performance characteristics are congruent with the intended scope of the test. The aim of the present study was to propose a practice model for implementing procedures employed for the verification of validated examination procedures already used for at least 2 years in our laboratory, in agreement with the ISO 15189 requirement at the Section 5.5.1.2. Methods In order to identify the operative procedure to be used, approved documents were identified, together with the definition of performance characteristics to be evaluated for the different methods; the examination procedures used in laboratory were analyzed and checked for performance specifications reported by manufacturers. Then, operative flow charts were identified to compare the laboratory performance characteristics with those declared by manufacturers. Results The choice of performance characteristics for verification was based on approved documents used as guidance, and the specific purpose tests undertaken, a consideration being made of: imprecision and trueness for quantitative methods; diagnostic accuracy for qualitative methods; imprecision together with diagnostic accuracy for semi-quantitative methods. Conclusions The described approach, balancing technological possibilities, risks and costs and assuring the compliance of the fundamental component of result accuracy, appears promising as an easily applicable and flexible procedure helping laboratories to comply with the ISO 15189 requirements

CFD MODELLING OF DISPERSION WITHIN RANDOMLY DISTRIBUTED CYLINDER ARRAYS

Vegetation has a significant role in reducing the negative effects of polluted water on natural water bodies. However, a lack of understanding with respect to vegetation-flow interactions may result in poorer performance than expected. The most common vegetation types have been modelled as cylinders by many researchers both in the laboratory and numerical studies. However, experimental studies face practical issues, such as the need for expensive equipment. The quality of the velocity and scalar transport data collected from laboratory setups is also often lower than expected. On the other hand, attempts to model flow and mixing within cylinder arrays using advanced CFD models, e.g. LES, are extremely computationally expensive and cannot be used to produce comparable data to that recorded in laboratory setups. This thesis proposes and validates the use of commercial less-computationally expensive CFD models (RSM models available in ANSYS FLUENT) as a complementary tool. This tool allows cylinder arrays to be modelled at the same scale as laboratory setups, provides high-resolution flow and turbulence data of high accuracy, and in combination with scalar transport modelling, provides estimated mixing coefficients of the same level of accuracy as those observed in laboratory studies. The general modelling methodology is built based on the results of a series of preliminary studies. These include novel studies on estimating the advective zone length and the minimum required mixing reach length necessary to provide the desired accuracy, both presented for the first time, as well a validation of the general methodology. The developed methodology was used to produce a new high-resolution and high-accuracy dataset. The main outcome of this thesis is a very convincing set of evidence that justifies the use of the CFD model as an alternative to traditional lab-based work. A few future studies are suggested to develop a deeper understanding of the processes that control mixing

Coronagraphic Low Order Wave Front Sensor : post-processing sensitivity enhancer for high performance coronagraphs

Detection and characterization of exoplanets by direct imaging requires a coronagraph designed to deliver high contrast at small angular separation. To achieve this, an accurate control of low order aberrations, such as pointing and focus errors, is essential to optimize coronagraphic rejection and avoid the possible confusion between exoplanet light and coronagraphic leaks in the science image. Simulations and laboratory prototyping have shown that a Coronagraphic Low Order Wave-Front Sensor (CLOWFS), using a single defocused image of a reflective focal plane ring, can be used to control tip-tilt to an accuracy of 10^{-3} lambda/D. This paper demonstrates that the data acquired by CLOWFS can also be used in post-processing to calibrate residual coronagraphic leaks from the science image. Using both the CLOWFS camera and the science camera in the system, we quantify the accuracy of the method and its ability to successfully remove light due to low order errors from the science image. We also report the implementation and performance of the CLOWFS on the Subaru Coronagraphic Extreme AO (SCExAO) system and its expected on-sky performance. In the laboratory, with a level of disturbance similar to what is encountered in a post Adaptive Optics beam, CLOWFS post-processing has achieved speckle calibration to 1/300 of the raw speckle level. This is about 40 times better than could be done with an idealized PSF subtraction that does not rely on CLOWFS.Comment: 10 pages, 7 figures, accepted for publication in PAS

Lyot-based Low Order Wavefront Sensor: Implementation on the Subaru Coronagraphic Extreme Adaptive Optics System and its Laboratory Performance

High throughput, low inner working angle (IWA) phase masks coronagraphs are essential to directly image and characterize (via spectroscopy) earth-like planets. However, the performance of low-IWA coronagraphs is limited by residual pointing errors and other low-order modes. The extent to which wavefront aberrations upstream of the coronagraph are corrected and calibrated drives coronagraphic performance. Addressing this issue is essential for preventing coronagraphic leaks, thus we have developed a Lyot-based low order wave front sensor (LLOWFS) to control the wavefront aberrations in a coronagraph. The LLOWFS monitors the starlight rejected by the coronagraphic mask using a reflective Lyot stop in the downstream pupil plane. The early implementation of LLOWFS at LESIA, Observatoire de Paris demonstrated an open loop measurement accuracy of 0.01 lambda/D for tip-tilt at 638 nm when used in conjunction with a four quadrant phase mask (FQPM) in the laboratory. To further demonstrate our concept, we have installed the reflective Lyot stops on the Subaru Coronagraphic Extreme AO (SCExAO) system at the Subaru Telescope and modified the system to support small IWA phase mask coronagraphs (< 1 lambda/D) on-sky such as FQPM, eight octant phase mask, vector vortex coronagraph and the phase induced amplitude apodization complex phase mask coronagraph with a goal of obtaining milli arc-second pointing accuracy. Laboratory results have shown the measurement of tip, tilt, focus, oblique and right astigmatism at 1.55 um for the vector vortex coronagraph. Our initial on-sky result demonstrate the closed loop accuracy of < 7 x 10-3 lambda/D at 1.6 um for tip, tilt and focus aberrations with the vector vortex coronagraph.Comment: 9 pages, 9 Figures, Proc. of SPIE Astronomical Telescopes + Instrumentation 201