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Arnold L. - One of the best experts on this subject based on the ideXlab platform.
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K-Stacker, an algorithm to hack the orbital parameters of planets hidden in high-contrast imaging. First applications to VLT SPHERE multi-epoch observations
'EDP Sciences', 2020Co-Authors: Le H. Coroller, Nowak M., Delorme P., Chauvin G., Gratton R., Devinat M., Bec-canet J., Schneeberger A., Estevez D., Arnold L.Abstract:Recent high-contrast imaging surveys, looking for planets in young, nearby systems showed evidence of a small number of giant planets at relatively large separation beyond typically 20 au where those surveys are the most sensitive. Access to smaller physical separations between 5 and 20 au is the next step for future planet imagers on 10 m telescopes and ELTs in order to bridge the gap with indirect techniques (radial velocity, transit, astrometry with Gaia). In that context, we recently proposed a new algorithm, Keplerian-Stacker, combining multiple observations acquired at different epochs and taking into account the orbital motion of a potential planet present in the images to boost the ultimate detection limit. We showed that this algorithm is able to find planets in time series of simulated images of SPHERE even when a planet remains undetected at one epoch. Here, we validate the K-Stacker algorithm performances on real SPHERE datasets, to demonstrate its resilience to instrumental speckles and the gain offered in terms of true detection. This will motivate future dedicated multi-epoch observation campaigns in high-contrast imaging to search for planets in emitted and reflected light. Results. We show that K-Stacker achieves high success rate when the SNR of the planet in the stacked image reaches 7. The improvement of the SNR ratio goes as the square root of the total exposure time. During the blind test and the redetection of HD 95086 b, and betaPic b, we highlight the ability of K-Stacker to find orbital solutions consistent with the ones derived by the state of the art MCMC orbital fitting techniques, confirming that in addition to the detection gain, K-Stacker offers the opportunity to characterize the most probable orbital solutions of the exoplanets recovered at low signal to noise.Comment: Astronomy & Astrophysics accepted, 13 Pages, 11 Figure
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K-Stacker: an algorithm to hack the orbital parameters of planets hidden in high-contrast imaging: First applications to VLT/SPHERE multi-epoch observations
'EDP Sciences', 2020Co-Authors: Le Coroller H., Nowak M., Delorme P., Chauvin G., Gratton R., Devinat M., Bec-canet J., Schneeberger A., Estevez D., Arnold L.Abstract:International audienceContext. Recent high-contrast imaging surveys, using the Spectro-Polarimetic High contrast imager for Exoplanets REsearch (SPHERE) or the Gemini Planet Imager in search of planets in young, nearby systems, have shown evidence of a small number of giant planets at relatively large separation beyond 10–30 au, where those surveys are the most sensitive. Access to smaller physical separations between 5 and 30 au is the next step for future planet imagers on 10 m telescopes and the next generation of extremely large telescopes in order to bridge the gap with indirect techniques such as radial velocity, transit, and soon astrometry with Gaia. In addition to new technologies and instruments, the development of innovative observing strategies combined with optimized data processing tools is participating in the improvement of detection capabilities at very close angular separation. In that context, we recently proposed a new algorithm, Keplerian-Stacker, which combines multiple observations acquired at different epochs and takes into account the orbital motion of a potential planet present in the images to boost the ultimate detection limit. We showed that this algorithm is able to find planets in time series of simulated images of the SPHERE InfraRed Dual-band Imager and Spectrograph (IRDIS) even when a planet remains undetected at one epoch.Aims. Our goal is to test and validate the K-Stacker algorithm performances on real SPHERE datasets to demonstrate the resilience of this algorithm to instrumental speckles and the gain offered in terms of true detection. This will motivate future dedicated multi-epoch observation campaigns of well-chosen, young, nearby systems and very nearby stars carefully selected to search for planets in emitted and reflected light, respectively, to open a new path concerning the observing strategy used with current and future planet imagers.Methods. To test K-Stacker, we injected fake planets and scanned the low signal-to-noise ratio (S/N) regime in a series of raw observations obtained by the SPHERE/IRDIS instrument in the course of the SPHERE High-contrast ImagiNg survey for Exoplanets. We also considered the cases of two specific targets intensively monitored during this campaign: β Pictoris and HD 95086. For each target and epoch, the data were reduced using standard angular differential imaging processing techniques and then recombined with K-Stacker to recover the fake planetary signals. In addition, the known exoplanets β Pictoris b and HD 95086 b previously identified at lower S/N in single epochs have also been recovered by K-Stacker.Results. We show that K-Stacker achieves a high success rate of ≈100% when the S/N of the planet in the stacked image reaches ≈9. The improvement of the S/N is given as the square root of the total exposure time contained in the data being combined. At S∕N < 6−7, the number of false positives is high near the coronagraphic mask, but a chromatic study or astrophysical criteria can help to disentangle between a bright speckle and a true detection. During the blind test and the redetection of HD 95086 b, and β Pic b, we highlightthe ability of K-Stacker to find orbital solutions consistent with those derived by the current Markov chain Monte Carlo orbital fitting techniques. This confirms that in addition to the detection gain, K-Stacker offers the opportunity to characterize the most probable orbital solutions of the exoplanets recovered at low S/N
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K-Stacker: an algorithm to hack the orbital parameters of planets hidden in high-contrast imaging. First applications to VLT/SPHERE multi-epoch observations
2020Co-Authors: Le Coroller H., Nowak M., Delorme P., Chauvin G., Gratton R., Devinat M., Bec-canet J., Schneeberger A., Estevez D., Arnold L.Abstract:Context. Recent high-contrast imaging surveys, using the Spectro- Polarimetic High contrast imager for Exoplanets REsearch (SPHERE) or the Gemini Planet Imager in search of planets in young, nearby systems, have shown evidence of a small number of giant planets at relatively large separation beyond 10-30 au, where those surveys are the most sensitive. Access to smaller physical separations between 5 and 30 au is the next step for future planet imagers on 10 m telescopes and the next generation of extremely large telescopes in order to bridge the gap with indirect techniques such as radial velocity, transit, and soon astrometry with Gaia. In addition to new technologies and instruments, the development of innovative observing strategies combined with optimized data processing tools is participating in the improvement of detection capabilities at very close angular separation. In that context, we recently proposed a new algorithm, Keplerian-Stacker, which combines multiple observations acquired at different epochs and takes into account the orbital motion of a potential planet present in the images to boost the ultimate detection limit. We showed that this algorithm is able to find planets in time series of simulated images of the SPHERE InfraRed Dual-band Imager and Spectrograph (IRDIS) even when a planet remains undetected at one epoch. Aims: Our goal is to test and validate the K-Stacker algorithm performances on real SPHERE datasets to demonstrate the resilience of this algorithm to instrumental speckles and the gain offered in terms of true detection. This will motivate future dedicated multi-epoch observation campaigns of well- chosen, young, nearby systems and very nearby stars carefully selected to search for planets in emitted and reflected light, respectively, to open a new path concerning the observing strategy used with current and future planet imagers. Methods: To test K-Stacker, we injected fake planets and scanned the low signal-to-noise ratio (S/N) regime in a series of raw observations obtained by the SPHERE/IRDIS instrument in the course of the SPHERE High-contrast ImagiNg survey for Exoplanets. We also considered the cases of two specific targets intensively monitored during this campaign: β Pictoris and HD 95086. For each target and epoch, the data were reduced using standard angular differential imaging processing techniques and then recombined with K-Stacker to recover the fake planetary signals. In addition, the known exoplanets β Pictoris b and HD 95086 b previously identified at lower S/N in single epochs have also been recovered by K-Stacker. Results: We show that K-Stacker achieves a high success rate of ≈100% when the S/N of the planet in the stacked image reaches ≈9. The improvement of the S/N is given as the square root of the total exposure time contained in the data being combined. At S/N Based on observations collected at the European Southern Observatory under programs: 095.C-0298, 096.C-0241, 097.C-0865, 198.C-0209, 099.C-0127.Peer reviewe
Yoga Coopoo - One of the best experts on this subject based on the ideXlab platform.
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relationship between energy expenditure and productivity of sugar cane cutters and Stackers
Occupational Medicine, 1994Co-Authors: Mike Lambert, E J Cheevers, Yoga CoopooAbstract:: The main aim of this study was to measure the energy expenditure of sugar cane cutters and Stackers during a normal working day and to relate this to their productivity (tonnes of cane cut or stacked per day). A secondary aim of the study was to relate the food and fluid ingestion of the workers during the day to energy expenditure, productivity and changes in body mass. Cutters (n = 12) and Stackers (n = 12), who were randomly selected from all the workers (n = 50) on a Natal sugar estate in South Africa, wore heart rate monitors for the entire working day (7 h +/- 30 min). On a separate occasion, all subjects underwent treadmill exercise tests in which oxygen consumption (VO2) and heart rate (HR) were measured simultaneously. A VO2-HR regression equation was calculated for each subject. Based on this regression equation, energy expenditure (kJ) for the working day was calculated for each subject. There was no difference in the mean productivity of the cutters (9.0 +/- 0.7 tonnes) compared to the Stackers (9.0 +/- 0.5 tonnes). Both groups expended a large and similar amount of energy during the working day (cutters = 11,695 +/- 1288 kJ; Stackers 14,127 +/- 1710 kJ). They ingested similar amounts of energy while working (cutters = 5179 +/- 161 kJ; Stackers = 5281 +/- 324 kJ). The best predictor of productivity was the length of the working day (r = 0.63), followed by the energy expended (r = 0.60). Despite the large amount of fluid ingested (up to 6.0 litres/day), some workers lost more than 3% of their body weight.(ABSTRACT TRUNCATED AT 250 WORDS)
Guan Yuming - One of the best experts on this subject based on the ideXlab platform.
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The mechanical property comparison of two kinds of counterweight booms of Stacker reclaimer
2016Co-Authors: Shang Peng, Qi Kaicheng, Wang Yaxu, Guan YumingAbstract:Abstract. This paper used the finite element method to compare the mechanical properties of two different configuration counterweight booms of the bucket wheel stacker reclaimer. And two different forms of the finite element analysis model of the counterweight booms were built in ANSYS. The stresses and strains under its working state were calculated. Then the impact of the counterweight arm to the force and stability of the whole rack could be analyzed. The results of this analysis provided a basis to select different types of the counterweight booms in different environment, and it has an important guidance and reference significance to the design and analysis of counterweight booms of large-scale machinery. Bucket wheel stacker reclaimer is a large-scale bulk material handling equipment widely used in ports, power, Coals and metallurgy industry. The design of bucket wheel stacker reclaimer mainly based on experience and analog [1-2]. Although it can meet the basic requirements of the design specifications, but a self-designed bucket wheel stacker reclaimer always exists difficulties such a
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The Modal Analysis of the Main steel structure of Bucket Wheel Stacker Reclaimer
2016Co-Authors: Shang Peng, Hu Yaozong, He Lihu, Guan YumingAbstract:Abstract. The vibration mode of main steel structure of bucket wheel stacker reclaimer is complex and changeable, so its modal analysis is necessary. In this paper, the main steel structure of bucket wheel stacker reclaimer was integrally designed and its main parameters were determined. then the finite element model of the main steel structure of the bucket wheel stacker reclaimer was established and the modal analysis was simulated, finally the results of its inherent frequency were calculated by FEA method
Javůrek František - One of the best experts on this subject based on the ideXlab platform.
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Shelf stacker for storing pallets in an automatic store
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010Co-Authors: Javůrek FrantišekAbstract:Target of the submitted work was a proposal of a new type of shelf Stackers in the range from 8 to 36 m that are working in fully automated warehouses. By using a fully automated storage system all human supervision in ordering pallets in a warehouse are canceled and everything is taken over by the control system. These stores are very efficient and save both time and money. With regard to safety requirements, regular inspections should be provided to the system. At the beginning of this work, there was done a short introduction to the particular study including the description of basic parts of the shelf Stackers. Consequently, there were done relevant computations for the drag device and its drive, drives for the travel and the finite method was used to the stress analysis of the mast shelf stacker. In the last part of this thesis is done a safety concept
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Shelf stacker for storing pallets in an automatic store
Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010Co-Authors: Javůrek FrantišekAbstract:Cílem předložené práce byl návrh nové typové řady regálových zakladačů v rozmezí od 8 do 36 m pracujících v plně automatizovaných skladech. Použitím plně automatizovaných skladů již odpadá jakýkoli lidský zásah do uspořádání palet ve skladu, vše má na starost řídící systém. Tyto sklady jsou velice efektivní, šetří čas i peníze. Vzhledem k bezpečnostním požadavkům je třeba zajistit pravidelné kontroly celého systému. Nejprve byl v práci proveden stručný úvod do dané problematiky včetně popsání základních částí regálového zakladače. Dále byly provedeny příslušné výpočty pro tažný prostředek a jeho pohon, navrženy pohony pro pojezd a pomocí metody konečných prvků provedeny pevnostní výpočty nosného sloupu regálového zakladače. V poslední části práce je zpracován návrh bezpečnostního konceptu.Target of the submitted work was a proposal of a new type of shelf Stackers in the range from 8 to 36 m that are working in fully automated warehouses. By using a fully automated storage system all human supervision in ordering pallets in a warehouse are canceled and everything is taken over by the control system. These stores are very efficient and save both time and money. With regard to safety requirements, regular inspections should be provided to the system. At the beginning of this work, there was done a short introduction to the particular study including the description of basic parts of the shelf Stackers. Consequently, there were done relevant computations for the drag device and its drive, drives for the travel and the finite method was used to the stress analysis of the mast shelf stacker. In the last part of this thesis is done a safety concept.
Bruce Anderson - One of the best experts on this subject based on the ideXlab platform.
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management of forages for stocker cattle
Veterinary Clinics of North America-food Animal Practice, 2006Co-Authors: Bruce AndersonAbstract:Successful grazing management of stockers requires knowledge of plant growth characteristics. Maintaining abundant leaf area is critical to support photosynthesis and plant growth as well as to provide nutritious grazing for the animals. Controlling stocking rate, stock density, and lengths of grazing and recovery periods can optimize individual animal rates of gain and gain per acre while maintaining pasture productivity. Various plant resources, perennial and annual, can be used strategically to provide the quantity and quality of forage needed by stockers throughout the year.