WORKSPACE-BASED ARCHITECTURE SELECTION OF A 3-DEGREE- OF-FREEDOM PLANAR PARALLEL MANIPULATOR

ABSTRACT This paper presents the workspace-based architecture selection process and singularity analysis of a high-speed, high-precision three degree-of-freedom (3-DOF) planar parallel manipulator for wirebonding and electronic-component placement applications. A novel concept of manipulator "effective base area" is utilized for selecting the optimal architecture amongst the possible six well-known configurations. Dexterity regions, based on the manipulator requirements, within the reachable workspace have been identified for the selected architecture. Singular configurations of the optimal 3-PRR architecture have also been examined within the reachable workspace. Simulation results for both workspace and singularity analyses are also presented

Behavioural impact assessment of unmanned aerial vehicles on Weddell seals (Leptonychotes weddellii)

The rapid increase in the use of unmanned aerial vehicles (UAVs) in wildlife research has raised concerns about its potential negative impact on animals. The paucity of studies and the variability of responses of pinnipeds to UAVs prompts the need for species-specific impact assessments. Here we assessed the potential behavioural impact of low altitude UAVs on Weddell seals (Leptonychotes weddellii). This is a preliminary step to envisage the feasibility of replacing and/or complementing traditional ground-based behavioural and morphometric measurements by potentially less invasive UAV aerial images. We flew a small UAV (DJI Mavic 2 zoom fitted with a phocid seal audiogram weighted source level of 84 dB re 20μPa (rms)) over 37 Weddell seals (3 adult males, 12 adult females and 22 mother-pup pairs) during the breeding season at Dumont D'Urville, East Antarctica. For each individual, we assessed the level of reaction during UAV overflights at three altitudes (25, 20 and 15 m) while factoring in pup presence and wind speed. For all altitudes and observations pooled together, Weddell seals predominantly (88%) showed little (vigilant) or no (resting) reactions towards the UAV. Moreover, only 27% of all individuals changed their initial activity during the sampling periods, and mothers rarely ended their nursing bouts (3%). While reactions were low overall, the probability of a stronger reaction occurring increased at lower altitudes, and varied among individuals. Neither the presence of pups nor a change in wind speed appear to influence individuals' response to the UAV significantly. However, on simpler histogram representations of the dataset, we observed the strongest reactions for females (n = 5) with a pup at wind speeds below 5 m.s−1 when ambient noise levels were lowest. While Weddell seals are likely to hear the UAV at 25 to 15 m altitude in low wind speeds, the low-level responses we observed are unlikely to negatively impact their energetic budget and/or reproductive success. Our results suggest a low impact of small UAV overflights of Weddell seals during the breeding season when flying ≥25 m. This allows for collection of high resolution images for behavioural and morphometric studies that can potentially replace more invasive data collection when capturing and handling the animals

Important areas and conservation sites for a community of globally threatened marine predators of the Southern Indian Ocean

International audienceIn the Southern Ocean, the impact of environmental changes and increasing human encroachment is causingdeclines in several populations of seabirds. Amsterdam island (77°33′E; 37°50′S) hosts some emblematic butglobally threatened seabird species with alarming population trends. In 2017, concerns about AmsterdamIsland's marine biodiversity led to the extension of a marine reserve to the boundaries of the exclusive economiczone (EEZ). Nevertheless, it is unknown whether this protected area is sufficiently large to encompass the mostimportant foraging hotspots of the threatened seabirds, particularly during key stages of their life cycle (e.g.breeding period). We analysed movements of four threatened seabird species using a tracking dataset acquiredover several breeding seasons from Amsterdam Island: Amsterdam albatross Diomedea amsterdamensis, sootyalbatross Phoebetria fusca, Indian yellow-nosed albatross Thalassarche carteri and northern rockhopper penguinEudyptes moseleyi. Our objectives were threefold: (1) characterise the at-sea distribution of the above-mentionedpopulations and delineate the marine Important Bird and Biodiversity Areas (mIBAs) triggered by them; (2)assess the potential threat at-sea by quantifying the overlap between seabird distribution and longline fishingefforts; (3) evaluate the coverage of identified mIBAs by marine protected areas and suggest complementaryconservation actions. The identified important areas fell within the boundaries of the EEZ, but vastly exceededthe former reserve. Thus, our results reinforce the justification of the recent expansion of the reserve to theboundaries of the EEZ. However, overall seabird distributions extended beyond the EEZ (5 to 50% of the locations)and we found substantial overlap with longline fishing in the high seas. Our results provide a spatiotemporalenvelope of where and when bycatch mitigation and observer coverage of longline fisheries should bemandated and enforced

Investigating annual diving behaviour by Hooded seals (Cystophora cristata) within the Northwest Atlantic Ocean

This work was funded through the Atlantic Seal Research Programme, International Governance Programme (DFO), the Greenland Institute of Natural Resources, and a CFI grant to YFW. The authors also acknowledge the support of the Marine Alliance for Science and Technology for Scotland (MASTS) pooling initiative in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.With the exception of relatively brief periods when they reproduce and moult, hooded seals, Cystophora cristata, spend most of the year in the open ocean where they undergo feeding migrations to either recover or prepare for the next fasting period. Valuable insights into habitat use and diving behaviour during these periods have been obtained by attaching Satellite Relay Data Loggers (SRDLs) to 51 Northwest (NW) Atlantic hooded seals (33 females and 18 males) during ice-bound fasting periods (2004−2008). Using General Additive Models (GAMs) we describe habitat use in terms of First Passage Time (FPT) and analyse how bathymetry, seasonality and FPT influence the hooded seals’ diving behaviour described by maximum dive depth, dive duration and surface duration. Adult NW Atlantic hooded seals exhibit a change in diving activity in areas where they spend >20 h by increasing maximum dive depth, dive duration and surface duration, indicating a restricted search behaviour. We found that male and female hooded seals are spatially segregated and that diving behaviour varies between sexes in relation to habitat properties and seasonality. Migration periods are described by increased dive duration for both sexes with a peak in May, October and January. Males demonstrated an increase in dive depth and dive duration towards May (post-breeding/pre-moult) and August–October (post-moult/pre-breeding) but did not show any pronounced increase in surface duration. Females dived deepest and had the highest surface duration between December and January (post-moult/pre-breeding). Our results suggest that the smaller females may have a greater need to recover from dives than that of the larger males. Horizontal segregation could have evolved as a result of a resource partitioning strategy to avoid sexual competition or that the energy requirements of males and females are different due to different energy expenditure during fasting periods.Publisher PDFPeer reviewe

Hydrographic influences on the summer dive behaviour of Weddell seals (Leptonychotes weddellii) in Atka Bay, Antarctica

In order to gain insights into species-level behavioural responses to the physical environment, it is necessary to obtain information from various populations and at all times of year. We analysed the influences of physical environmental parameters on the mid-summer dive behaviour of Weddell seals (Leptonychotes weddellii) from a little-known population at Atka Bay, Antarctica. Dive depth distributions followed a typical bimodal pattern also exhibited by seals from other populations and seals targeted both shallow water layers of less than 50 m and depths near the seafloor. Increased stratification of temperature layers within the water column resulted in increased forage efforts by the seals through relatively high numbers of dives to the seafloor, as well as forage effort associated with shallow dives. We interpret these behavioural responses to be due to increased water temperature stratification resulting in the concentration of prey species in particular depth layers

Characterising Essential Fish Habitat using spatio‐temporal analysis of fishery data: A case study of the European seabass spawning areas

Fish habitats sustain essential functions for fish to complete their life cycle, such as feeding, growing and spawning. Conservation is crucial to maintain fish populations and their exploitation. Since 2013, the spawning stock biomass of the northern stock of European seabass (Dicentrarchus labrax) has been in a worrying state. A series of low recruitments with a persistently high level of fishing has been blamed, raising concerns about the processes involved in seabass reproduction and settlement in nurseries. Here, we characterise seabass spawning areas along the French Atlantic coast using vessel monitoring system (VMS) data. A non‐linear geostatistical approach was applied, from 2008 to 2014, to detect locations where seabass aggregate for spawning. Occurrence maps of spawning distribution were combined into probability maps to quantify the seasonal and inter‐annual variability and to highlight recurrent, occasional and unfavourable spawning areas. We identified three main spawning areas: the Rochebonne Plateau in the Bay of Biscay, the Western English Channel and the North of the Cotentin peninsula in the Eastern English Channel. The correlative link between this geographical distribution and environmental factors was investigated using a Bayesian spatio‐temporal model. The spatio‐temporal structure accounted for the vast majority of the model predictive skills, whereas environmental covariates had a negligible effect. Our model revealed the persistence of the spatial distribution of spawning areas with intra‐ and inter‐annual variability. Offshore areas appear to be essential spawning areas for seabass, and should be considered in spatial management strategies