An Interval Approach to Multiple Unmanned Aerial Vehicle Collision Avoidance

Small/micro Unmanned Aerial Systems (UAVs) require the ability to operate with constraints of a diverse, automated airspace where obstacle telemetry is denied. This paper proposes a novel Sense, Detect and Avoid (SDA) algorithm with inherit resilience to sensor uncertainty. This is achieved through the interval geometric formulation of the avoidance problem, which by the use of interval analysis, can be extended to consider multiple obstacles. The approach is shown to demonstrate the ability to both tolerate sensor uncertainty and enact generated 3D avoidance trajectories. Monte-Carlo simulations demonstrate successful avoidance rates of 88%, 96% and 91% in two example collision scenarios and one multi-agent conflict scenario respectively

Mass Determination of Groups of Galaxies: Effects of the Cosmological Constant

The spherical infall model first developed by Lema\^{i}tre and Tolman was modified in order to include the effects of a dark energy term. The resulting velocity-distance relation was evaluated numerically. This equation, when fitted to actual data, permits the simultaneous evaluation of the central mass and of the Hubble parameter. Application of this relation to the Local Group, when the dark energy is modeled by a cosmological constant, yields a total mass for the M31-Milky Way pair of (2.5 +/- 0.7) x 10^12 M\_sun, a Hubble parameter H\_0 = 74 +/- 4 km s^-1 Mpc^-1 and a 1-D velocity dispersion for the flow of about 39 km s^-1. The zero-velocity and the marginally bound surfaces of the Local Group are at about 1.0 and 2.3 Mpc respectively from the center of mass. A similar analysis for the Virgo cluster yields a mass of (1.10 +/- 0.12) x 10^15 M\_sun and H\_0 = 65 +/- 9 km s^-1 Mpc^-1. The zero-velocity is located at a distance of 8.6 +/- 0.8 Mpc from the center of the cluster. The predicted peculiar velocity of the Local Group towards Virgo is about 190 kms^-1, in agreement with other estimates. Slightly lower masses are derived if the dark energy is represented by a fluid with an equation of state P = w\epsilon with w = -2/3.Comment: 13 pages, 3 figures. Version to appear in New Astronomy. Typing errors corrected in relation (1) and in percentage value in page

A landscape ecological vegetation map of Sint Eustatius (Lesser Antilles)

A semi-detailed landscape-based vegetation map (scale: 1: 37,500) based on field data from 1999 has been available as an update of Stoffers’ 1956 map of the Lesser Antillean island of St. Eustatius, Netherlands Caribbean, but up to now was never finalized or published. In this report we complete the documentation of that map to provide new insights into vegetation change over a period of more than 40 years, and a quantitative reference point for future studies on landscape-level vegetation development for the island

Preliminary inventory of key terrestrial nature values of Bonaire

Based on a helpdesk question from the Dutch Ministry of Economic Affairs, Agriculture and Innovation (EL&I) a preliminary inventory is given of key terrestrial nature values of Bonaire in order to determine their occurrence in relation to areas designated as “nature” and “open landscape”, according to the Spatial development plan of Bonaire. This was based on a literature study and supplemented by expert advice

747-1 Progression of Aortic Regurgitation Assessed by Doppler Echocardiography in 127 Patients: Degree of Regurgitation

To assess the progression of chronic aortic regurgitation (AR), 127 patients 169 men; 59±21 yr) with AR (59 mild, 8 mild-to-moderate, 41 moderate, 4 moderate-to-severe, 15 severe) who had ≥6 months of follow-up (6–47 months) by color Doppler and 2-D echo were studied. The degree of AR was established at entry and follow-up studies using an algorithm (semi-quantitative) that takes into account several Doppler criteria (jet area and jet height ratios, jet length, pressure half-time, reversal of flow in descending aorta) and the jet height/LV outflow tract (LVOT) height ratio (quantitative). LV volume (Simpson) and LV mass (Devereux) were calculated. A significant increase in jet/LVOT height ratio was observed in the whole population (30±17 vs. 35±20%; p<0.00001) and in the subsets of patients with mild (18±7 vs. 22.3±9%; p<0.01), moderate (40±14 vs. 44±16%; p<0.01) and severe (54±19 vs. 65±15%; p<0.05) AR. An increase in the degree of AR (semi-quantitative) during the follow-up was observed in 38 (30%) of patients: 25% with mild, 37% with mild-to-moderate, 44% with moderate and 50% with moderate-to-severe AR (p<0.006). Patients were further divided according to the rank order in the rate of progression of jet/LVOT height ratio into “progressives” (n=18; rate>5.64%/yr) and “non-progressives” (n=109). Patients with “progressive” AR had a faster rate of progression of LV end-diastolic volume, LV end-systolic volume and LV mass than “non-progressives” (p<0.025).ConclusionsAR is a progressive disease even in patients with mild insufficiency. The progression in the degree of AR is more frequent in patients with more severe disease. The rate of progression of regurgitation appears to playa role in LV overload in patients with AR

Key elements towards a Joint Invasive Alien Species Strategy for the Dutch Caribbean

Recent inventories have documented no less than 211 exotic alien species in the wild for the Dutch Caribbean. These amount to no less than 27 introduced marine species, 65 introduced terrestrial plants, 72 introduced terrestrial and freshwater animals and 47 introduced agricultural pests and diseases. A list of these species, pests and diseases are found in resp. Debrot et al. (2011), Van der Burg et al. 2012, and Van Buurt and Debrot (2012, 2011). The rate of introductions and establishment of invasive alien species (IAS) worldwide has grown rapidly as a result of increasing globalisation. Invasive species cause major ecological effects (decimating native flora or fauna populations) as well as economic losses to these islands, across sectors such as agriculture (diseases, weeds and vectors), fisheries (fish diseases and the lionfish), industry (rodents and termites), tourism (roadside weedy species) and public health (mosquitos). Recently in Curaçao the kissing bug Triatoma infestans was found; this is a vector for Chagas disease. It almost certainly came in with palm leaves imported from South America to be used as roof covering for recreational beach “palapa’s”

Indirect search for dark matter: prospects for GLAST

Possible indirect detection of neutralino, through its gamma-ray annihilation product, by the forthcoming GLAST satellite from our galactic halo, M31, M87 and the dwarf galaxies Draco and Sagittarius is studied. Gamma-ray fluxes are evaluated for the two representative energy thresholds, 0.1 GeV and 1.0 GeV, at which the spatial resolution of GLAST varies considerably. Apart from dwarfs which are described either by a modified Plummer profile or by a tidally-truncated King profiles, fluxes are compared for halos with central cusps and cores. It is demonstrated that substructures, irrespective of their profiles, enhance the gamma-ray emission only marginally. The expected gamma-ray intensity above 1 GeV at high galactic latitudes is consistent with the residual emission derived from EGRET data if the density profile has a central core and the neutralino mass is less than 50 GeV, whereas for a central cusp only a substantial enhancement would explain the observations. From M31, the flux can be detected above 0.1 GeV and 1.0 GeV by GLAST only if the neutralino mass is below 300 GeV and if the density profile has a central cusp, case in which a significant boost in the gamma-ray emission is produced by the central black hole. For Sagittarius, the flux above 0.1 GeV is detectable by GLAST provided the neutralino mass is below 50 GeV. From M87 and Draco the fluxes are always below the sensitivity limit of GLAST.Comment: 14 Pages, 7 Figures, 3 Tables, version to appear on Physical Review