Context.
Despite tremendous progress in the detection and characterization of extrasolar planetary systems in the last 25 yr, we have not pinpointed any Solar System analogues. In particular, ...Jupiter-like planets (either mature or old) are barely detectable beyond 5 au with indirect techniques and they are still out of the reach of direct imaging techniques.
Aims.
Our study is aimed at a search for exoplanets throughout the whole ESO/VLT-SPHERE archive with an improved and unsupervised data analysis algorithm that could allow us to detect massive giant planets at 5 au. To prepare, test, and optimize our approach, we gathered a sample of 24 solar-type stars observed with SPHERE using angular and spectral differential imaging modes.
Methods.
We used PACO, a recently developed new-generation algorithm that has been shown to outperform classical methods. We also improved the SPHERE pre-reduction pipeline and optimized the outputs of PACO to enhance the detection performance. We developed custom-built spectral prior libraries to optimize the detection capability of the ASDI mode for both IRDIS and IFS.
Results.
Compared to previous works conducted with more classical algorithms, the contrast limits we derived with PACO are more reliable and significantly improved, especially at short angular separations, where a gain by a factor ten has been obtained between 0.2 and 0.5 arcsec. Under good observing conditions, planets down to 5
M
Jup
, orbiting at 5 au could be detected around stars within 60 parsec. We identified two exoplanet candidates that will require a follow-up to test for a common proper motion.
Conclusions.
In this work, we use a small sample to demonstrate the benefits of PACO in terms of achievable contrast and of control of the confidence levels. In addition, we have developed custom tools to take full advantage of this algorithm and to quantity the total error budget on the estimated astrometry and photometry. This work paves the way towards an end-to-end, homogeneous, and unsupervised massive re-reduction of archival direct imaging surveys in the quest for new exo-Jupiters.
Context.
Since 2019, the direct imaging B-star Exoplanet Abundance STudy (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of ...giant planet formation. Recently, the 17
−4
+3
Myr HIP 81208 was found to host a close-in (∼50 au) brown dwarf and a wider (∼230 au) late M star around the central 2.6
M
⊙
primary.
Aims.
Alongside the continuation of the survey, we are undertaking a complete reanalysis of archival data aimed at improving detection performances so as to uncover additional low-mass companions.
Methods.
We present here a new reduction of the observations of HIP 81208 using the patch covariance algorithm (PACO), a recent and powerful algorithm dedicated to processing high-contrast imaging datasets, as well as more classical algorithms and a dedicated point spread function subtraction approach. The combination of different techniques allowed for a reliable extraction of astrometric and photometric parameters.
Results.
A previously undetected source was recovered at a short separation from the C component of the system. Proper motion analysis provided robust evidence for the gravitational bond of the object to HIP 81208 C. Orbiting C at a distance of ∼20 au, this 15
M
Jup
brown dwarf becomes the fourth object of the hierarchical HIP 81208 system.
Conclusions.
Among the several BEAST stars which are being found to host substellar companions, HIP 81208 stands out as a particularly striking system. As the first stellar binary system with substellar companions around each component ever found by direct imaging, it yields exquisite opportunities for thorough formation and dynamical follow-up studies.
We aim at searching for exoplanets on the whole ESO/VLT-SPHERE archive with improved and unsupervised data analysis algorithm that could allow to detect massive giant planets at 5 au. To prepare, ...test and optimize our approach, we gathered a sample of twenty four solar-type stars observed with SPHERE using angular and spectral differential imaging modes. We use PACO, a new generation algorithm recently developed, that has been shown to outperform classical methods. We also improve the SPHERE pre-reduction pipeline, and optimize the outputs of PACO to enhance the detection performance. We develop custom built spectral prior libraries to optimize the detection capability of the ASDI mode for both IRDIS and IFS. Compared to previous works conducted with more classical algorithms than PACO, the contrast limits we derived are more reliable and significantly better, especially at short angular separations where a gain by a factor ten is obtained between 0.2 and 0.5 arcsec. Under good observing conditions, planets down to 5 MJup, orbiting at 5 au could be detected around stars within 60 parsec. We identified two exoplanet candidates that require follow-up to test for common proper motion. In this work, we demonstrated on a small sample the benefits of PACO in terms of achievable contrast and of control of the confidence levels. Besides, we have developed custom tools to take full benefits of this algorithm and to quantity the total error budget on the estimated astrometry and photometry. This work paves the way towards an end-to-end, homogeneous, and unsupervised massive re-reduction of archival direct imaging surveys in the quest of new exoJupiters.
IC design is driven by two simultaneous trends: miniaturization of microelectronics technology, and telecommunication market expansion. When considered at a user level, these trends seem to be ...compatible: by making devices smaller, integration of a larger number of functionalities in your smart phone is made possible and thus boosts the development of the telecom market. From an IC designer point of view, both trends are challenging: On one side, the technology shrinkage, makes components/MEMS/circuits more and more sensitive to design/process parameter variations. This requires more than ever accurate predictions as early as possible in the design flow and better collaborations between designers and technologists. . On the other side, time-to-market diktat imposes short design cycles. Up to now, these constraints have been handled using iterative and time consuming techniques such as iterative try-and-error loops at design step and iterative loops between designers and technologists In order to overcome the IC design bottleneck InfiniScale 1 approach offers a proven solution by proceeding to a smart use of designers/technologists/physicists experiences. This solution based upon innovative and cost-effective behavioral modeling techniques, and a complete model-based flow generates designs optimized for performance in matters of hours. This paper presents the InfiniScale total solutions flow (modeling and sizing) applied to a ST microelectronics planar integrated inductor.
Since 2019, the direct imaging B-star Exoplanet Abundance Study (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of giant ...planet formation. Recently, the \(17^{+3}_{-4}\) Myr HIP 81208 was found to host a close-in (~50 au) brown dwarf and a wider (~230 au) late M star around the central 2.6Msun primary. Alongside the continuation of the survey, we are undertaking a complete reanalysis of archival data aimed at improving detection performances so as to uncover additional low-mass companions. We present here a new reduction of the observations of HIP 81208 using PACO ASDI, a recent and powerful algorithm dedicated to processing high-contrast imaging datasets, as well as more classical algorithms and a dedicated PSF-subtraction approach. The combination of different techniques allowed for a reliable extraction of astrometric and photometric parameters. A previously undetected source was recovered at a short separation from the C component of the system. Proper motion analysis provided robust evidence for the gravitational bond of the object to HIP 81208 C. Orbiting C at a distance of ~20 au, this 15Mjup brown dwarf becomes the fourth object of the hierarchical HIP 81208 system. Among the several BEAST stars which are being found to host substellar companions, HIP 81208 stands out as a particularly striking system. As the first stellar binary system with substellar companions around each component ever found by direct imaging, it yields exquisite opportunities for thorough formation and dynamical follow-up studies.
A computer aided sizing (CAS) approach of a static power converter is presented: it lays on the translation of the sizing problem into a constrained optimisation problem. The paper mainly focuses on ...the way to carry out this translation with computer techniques, and it shows how symbolic methods are powerful in such an approach. In this aim, the paper presents: the optimisation problem; the way to solve it; the authors' approach; and their choice on the model building.
The basis of a CAD approach for the sizing of a static converter is presented: it lays on the translation of the sizing problem into a constrained optimisation problem. The paper mainly focuses on ...the way to carry out this translation with computer techniques, and it shows how symbolic methods are powerful in such an approach. With this aim, the paper presents: the optimisation problem, the way to solve it, our approach and our choice, and an example of a sizing problem treated with our methodology.
In our days, data centers provide the global community with an indispensable service: nearly unlimited access to almost any kind of information by supporting Internet services such as Web hosting or ...E-commerce services. With the increasing demand of information, data centers consume a great amount of energy. The resulting high utility costs is reason enough to address power consumption. In this paper a data center energy model is proffered along with an optimization energy management algorithm designed to increase the overall IT energy efficiency. The energy model and the optimization algorithm are taking into account a global overview of the data center (power distribution units, cooling system and the IT system). A power management algorithm is proposed and it is shown that it yiels good energy gain in comparison with the known scheduling algorithms.
Vehicle sequencing based on evolutionary computation Jie Cheng; Yi Lu; Puskorius, G. ...
Proceedings of the 1999 Congress on Evolutionary Computation-CEC99 (Cat. No. 99TH8406),
1999, Letnik:
2
Conference Proceeding
A critical component for the efficient manufacturing of vehicles is an assembly scheduling tool that allows for the economic utilization of time and resources. From a computational perspective, ...vehicle scheduling can be characterized as a combinatorial constraint satisfaction and optimization problem that is NP-complete and for which exhaustive search methods are impractical. To date, heuristic approaches, based on a rank ordering of the relative importance of different types of constraints, have been used for the development of assembly sequences. Although these heuristic approaches have been beneficially applied, they are not easily adapted to incorporate new and more complicated scheduling constraints. We describe a practical and extensible approach for the development of assembly sequences based on methods of evolutionary computation (EC). We demonstrate that the resulting procedure, which we refer to as EC-VS, discovers desirable vehicle assembly sequences for complex problems in an efficient and effective fashion. A production version has been developed and is now deployed at a Ford vehicle assembly plant.
