Helicopter roll control effectiveness criteria program summary

A study of helicopter roll control effectiveness is summarized for the purpose of defining military helicopter handling qualities requirements. The study is based on an analysis of pilot-in-the-loop task performance of several basic maneuvers. This is extended by a series of piloted simulations using the NASA Ames Vertical Motion Simulator and selected flight data. The main results cover roll control power and short-term response characteristics. In general the handling qualities requirements recommended are set in conjunction with desired levels of flight task and maneuver response which can be directly observed in actual flight. An important aspect of this, however, is that vehicle handling qualities need to be set with regard to some quantitative aspect of mission performance. Specific examples of how this can be accomplished include a lateral unmask/remask maneuver in the presence of a threat and an air tracking maneuver which recognizes the kill probability enhancement connected with decreasing the range to the target. Conclusions and recommendations address not only the handling qualities recommendations, but also the general use of flight simulators and the dependence of mission performance on handling qualities

Exact vortex nucleation and cooperative vortex tunneling in dilute BECs

With the imminent advent of mesoscopic rotating BECs in the lowest Landau level (LLL) regime, we explore LLL vortex nucleation. An exact many-body analysis is presented in a weakly elliptical trap for up to 400 particles. Striking non-mean field features are exposed at filling factors >>1 . Eg near the critical rotation frequency pairs of energy levels approach each other with exponential accuracy. A physical interpretation is provided by requantising a mean field theory, where 1/N plays the role of Planck's constant, revealing two vortices cooperatively tunneling between classically degenerate energy minima. The tunnel splitting variation is described in terms of frequency, particle number and ellipticity.Comment: 4 pages,4 figure

The complex effect of gas cooling and turbulence on AGN-driven outflow properties

© 2024 The Author(s). Published by EDP Sciences. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/Context. Accretion onto supermassive black holes at close to the Eddington rate is expected to drive powerful winds, which have the potential to majorly influence the properties of the host galaxy. Theoretical models of such winds can simultaneously explain observational correlations between supermassive black holes and their host galaxies, such as the M − σ relation, and the powerful multi-phase outflows that are observed in a number of active galaxies. Analytic models developed to understand these processes usually assume simple galaxy properties, namely spherical symmetry and a smooth gas distribution with an adiabatic equation of state. However, the interstellar medium in real galaxies is clumpy and cooling is important, complicating the analysis. Aims. We wish to determine how gas turbulence, uneven density distribution, and cooling influence the development of active galactic nucleus (AGN) wind-driven outflows and their global properties on kiloparsec scales. Methods. We calculated a suite of idealised hydrodynamical simulations of AGN outflows designed to isolate the effects of turbulence and cooling, both separately and in combination. All simulations initially consisted of a 1 kpc gas shell with an AGN in the centre. We measured the main outflow parameters – the velocity, the mass outflow rate (Ṁout), and the momentum (ṗoutc/LAGN) and energy (Ėout/LAGN) loading factors – as the system evolves over 1.2 Myr and estimated plausible observationally derived values. Results. We find that adiabatic simulations approximately reproduce the analytical estimates of outflow properties independently of the presence or absence of turbulence and clumpiness. Cooling, on the other hand, has a significant effect, reducing the outflow energy rate by one to two orders of magnitude in the smooth simulations and by up to one order of magnitude in the turbulent ones. The interplay between cooling and turbulence depends on AGN luminosity: in Eddington-limited AGN, turbulence enhances the coupling between the AGN wind and the gas, while in lower-luminosity simulations, the opposite is true. This mainly occurs because dense gas clumps are resilient to low-luminosity AGN feedback but get driven away by high-luminosity AGN feedback. The overall properties of multi-phase outflowing gas in our simulations qualitatively agree with observations of multi-phase outflows, although there are some quantitative differences. We also find that using ‘observable’ outflow properties leads to their parameters being underestimated by a factor of a few compared with real values. Conclusions. We conclude that the AGN wind-driven outflow model is capable of reproducing realistic outflow properties in close-to-realistic galaxy setups and that the M − σ relation can be established without efficient cooling of the shocked AGN wind. Furthermore, we suggest ways to improve large-scale numerical simulations by accounting for the effects of AGN wind.Peer reviewe

Anomalous hydrodynamics and "normal" fluids in rapidly rotating BECs

In rapidly rotating bose systems we show that there is a region of anomalous hydrodynamics whilst the system is still condensed, which coincides with the mean field quantum Hall regime. An immediate consequence is the absence of a normal fluid in any conventional sense. However, even the superfluid hydrodynamics is not described by conventional Bernoulli and continuity equations. We show there are kinematic constraints which connect spatial variations of density and phase, that the positions of vortices are not the simplest description of the dynamics of such a fluid (despite their utility in describing the instantaneous state of the condensate) and that the most compact description allows solution of some illuminating examples of motion. We demonstrate, inter alia, a very simple relation between vortices and surface waves. We show the surface waves can form a "normal fluid" which absorbs energy and angular momentum from vortex motion in the trap. The time scale of this process is sensitive to the initial configuration of the vortices, which can lead to long-lived vortex patches - perhaps related to those observed at JILA.Comment: 4 pages; 1 sentence and references modifie

Study of helicopterroll control effectiveness criteria

A study of helicopter roll control effectiveness based on closed-loop task performance measurement and modeling is presented. Roll control critieria are based on task margin, the excess of vehicle task performance capability over the pilot's task performance demand. Appropriate helicopter roll axis dynamic models are defined for use with analytic models for task performance. Both near-earth and up-and-away large-amplitude maneuvering phases are considered. The results of in-flight and moving-base simulation measurements are presented to support the roll control effectiveness criteria offered. This Volume contains the theoretical analysis, simulation results and criteria development

T-PHOT version 2.0: improved algorithms for background subtraction, local convolution, kernel registration, and new options

We present the new release v2.0 of T-PHOT, a publicly available software package developed to perform PSF-matched, prior-based, multiwavelength deconfusion photometry of extragalactic fields. New features included in the code are presented and discussed: background estimation, fitting using position dependent kernels, flux prioring, diagnostical statistics on the residual image, exclusion of selected sources from the model and residual images, individual registration of fitted objects. These new options improve on the performance of the code, allowing for more accurate results and providing useful aids for diagnostics.Comment: 7 pages, 8 figure

Single-Crystal-to-Single-Crystal Transformation of a Novel 2-Fold Interpenetrated Cadmium-Organic Framework with Trimesate and 1,2-Bis(4-pyridyl)ethane into the Thermally Desolvated Form Which Exhibits Liquid and Gas Sorption Properties

A novel 2-fold interpenetrated pillared cadmium metal organic framework namely [Cd(HBTC)-BPE](n)center dot nDMF has been synthesized using 1,3,5-benzenetricarboxylic acid and 1,2-bis(4-pyridyl)ethane (BPE). This compound has been desolvated and subjected to various liquids and gases for sorption studies. Structures of the assynthesized (1) desolvated (2) and resolvated in benzene (3) have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis IR spectra, and thermogravimetric/differential scanning calorimetry analysis. Single crystal X-ray analysis revealed a 2-fold interpenetrated, three-dimensional (3D) framework which exhibits a 3,5-connected network with the Schlafli symbol of [(6(3))(6(9).8) and hms topology. Compound I exhibits a temperature-induced single-crystal-to-single-crystal (SC SC) transformation upon the release of N,N'-dimethylformamide molecules forming compound 2 (stable up to 300 C). SC SC transformation is also observed when it is immersed in benzene, chloroform, 1,4dioxane, and tetrahydrofuran. The uptake of different solvent molecules was analyzed, and desolvated samples selectively adsorb benzene, chloroform, 1,4-dioxane, and THF molecules over other selected polar solvents. Gas (N-2, CO2, and N2O) sorption experiments were also performed and the structure showed 2.5% N-2 4.5% CO2, and 3.4% N2O absorption by mass at room temperature and moderate gas pressures (similar to 10 bar)

Individual level peer interventions for gay and bisexual men who have sex with men between 2000 and 2020: A scoping review

Background Peer-led interventions are central to the global HIV response for gay and bisexual men who have sex with men [GBMSM]. Since the year 2000, technological advancements in HIV and an increased response to the health disparities faced by GBMSM outside of HIV, have contributed to the expanding scope of their content and delivery. This review sets out to characterise the evidence base for individual level peer interventions for GBMSM, overview approaches to implementing and evaluating them and identify future priorities for their delivery and evaluation. Methods A scoping review methodology was applied and evaluations of peer programs for GBMSM published in peer reviewed journals were identified via subject heading and keyword searches across five electronic databases. Titles and abstracts were reviewed, and full texts were assessed against eligibility criteria. A coding framework was used to extract data from included studies against intervention implementation and evaluation components. Results A total of 38 studies evaluating peer led interventions against effectiveness outcomes were deemed eligible for inclusion and coded into four intervention modalities; peer counselling [n = 6], groupwork programs [n = 15], peer navigation [n = 7] and peer education [n = 10]. Most addressed HIV [n = 32] and across intervention modalities, evaluations demonstrated compelling evidence of significant effect. Intervention effects on broader indicators of psychosocial wellbeing were not extensively evaluated. Expertise regarding the implementation and evaluation of peer interventions addressing HIV among GBMSM ought to be leveraged to expand the scope of peer intervention to meet the diverse health and wellbeing needs of GBMSM