Apodized-pupil Lyot coronagraphs: multistage designs for extremely large telescopes

Earlier apodized-pupil Lyot coronagraphs (APLC) have been studied and developed to enable high-contrast imaging for exoplanet detection and characterization with present-day ground-based telescopes. With the current interest in the development of the next generation of telescopes, the future extremely large telescopes (ELTs), alternative APLC designs involving multistage configuration appear attractive. The interest of these designs for application to ELTs is studied. Performance and sensitivity of multistage APLC to ELT specificities are analyzed and discussed, taking into account several ineluctable coronagraphic telescope error sources by means of numerical simulations. Additionally, a first laboratory experiment with a two-stages-APLC in the near-infrared (H-band) is presented to further support the numerical treatment. Multistage configurations are found to be inappropriate to ELTs. The theoretical gain offered by a multistage design over the classical single-stage APLC is largely compromised by the presence of inherent error sources occurring in a coronagraphic telescope, and in particular in ELTs. The APLC remains an attractive solution for ELTs, but rather in its conventional single-stage configuration.Comment: A&A accepte

How to Model Condensate Banking in a Simulation Model to Get Reliable Forecasts? Case Story of Elgin/Franklin

Imperial Users onl

A Study on the Integration of a High-Speed Flywheel as an Energy Storage Device in Hybrid Vehicles

The last couple of decades have seen the rise of the hybrid electric vehicle as a compromise between the outstanding specific energy of petrol fuels and its low-cost technology, and the zero tail-gate emissions of the electric vehicle. Despite this, considerable reductions in cost and further increases in fuel economy are needed for their widespread adoption. An alternative low-cost energy storage technology for vehicles is the high-speed flywheel. The flywheel has important limitations that exclude it from being used as a primary energy source for vehicles, but its power characteristics and low-cost materials make it a powerful complement to a vehicle's primary propulsion system. This thesis presents an analysis on the integration of a high-speed flywheel for use as a secondary energy storage device in hybrid vehicles. Unlike other energy storage technologies, the energy content of the flywheel has a direct impact on the velocity of transmission. This presents an important challenge, as it means that the flywheel must be able to rotate at a speed independent of the vehicle's velocity and therefore it must be coupled via a variable speed transmission. This thesis presents some practical ways in which to accomplish this in conventional road vehicles, namely with the use of a variator, a planetary gear set or with the use of a power-split continuously variable transmission. Fundamental analyses on the kinematic behaviour of these transmissions particularly as they pertain to flywheel powertrains are presented. Computer simulations were carried out to compare the performance of various transmissions, and the models developed are presented as well. Finally the thesis also contains an investigation on the driving and road conditions that have the most beneficial effect on hybrid vehicle performance, with a particular emphasis on the effect that the road topography has on fuel economy and the significance of this

New measurements of magnetic fields of roAp stars with FORS1 at the VLT

Magnetic fields play a key role in the pulsations of rapidly oscillating Ap (roAp) stars since they are a necessary ingredient of all pulsation excitation mechanisms proposed so far. This implies that the proper understanding of the seismological behaviour of the roAp stars requires knowledge of their magnetic fields. However, the magnetic fields of the roAp stars are not well studied. Here we present new results of measurements of the mean longitudinal field of 14 roAp stars obtained from low resolution spectropolarimetry with FORS1 at the VLT.Comment: 5 pages, accepted for publication in A&

Toxic Masculinity: An Outcome of Colonialism and its Effects on the Latinx/Chicanx LGBTQ+ Community

This research examines masculinity in the Latinx community within the U.S. Much of the theory behind masculinity involves discussing toxic masculinity and machismo. To do this, I look at film, poetry, and literature to discuss how toxic masculinity affects Queer Latinxs. Although this research focuses on fictional characters and the analysis of fictional works, these characters’ stories do not fall far from current LGBTQ+ Latinxs who may be experiencing the same issues. I examine La Mission, Mosquita y Mari, Gun Hill Road, “I am Joaquin,” “La Loca de la Raza Cosmica,” Rain God, and What Night Brings. These pieces work well with one another to show how gay Latino men, Latina lesbian women, and transgender Latina women are affected by toxic masculinity, internalized homophobia and transphobia. With this research I hope to show how the way we construct masculinity as a society, should be reconfigured to something more positive; I also hope to eliminate homophobia and transphobia, as well as violence and hate crimes towards the LGBTQ+ community

Key Features of the Entry, Descent, and Landing Repository

This presentation was part of the session : Poster SessionsSixth International Planetary Probe WorkshopThis poster will illustrate the key features of the Entry, Descent, and Landing Repository (EDL-R) web application. Features of keen interest, such as security, multiple search methods, the submission process, and automatic notification, will be highlighted. Also, the motivation for the task and future plans will be summarized.NASA Engineering and Safety Cente