Pose and Shape Reconstruction of a Noncooperative Spacecraft Using Camera and Range Measurements

Recent interest in on-orbit proximity operations has pushed towards the development of autonomous GNC strategies. In this sense, optical navigation enables a wide variety of possibilities as it can provide information not only about the kinematic state but also about the shape of the observed object. Various mission architectures have been either tested in space or studied on Earth. The present study deals with on-orbit relative pose and shape estimation with the use of a monocular camera and a distance sensor. The goal is to develop a filter which estimates an observed satellite's relative position, velocity, attitude, and angular velocity, along with its shape, with the measurements obtained by a camera and a distance sensor mounted on board a chaser which is on a relative trajectory around the target. The filter's efficiency is proved with a simulation on a virtual target object. The results of the simulation, even though relevant to a simplified scenario, show that the estimation process is successful and can be considered a promising strategy for a correct and safe docking maneuver

Simultaneous multi-band detection of Low Surface Brightness galaxies with Markovian modelling

We present an algorithm for the detection of Low Surface Brightness (LSB) galaxies in images, called MARSIAA (MARkovian Software for Image Analysis in Astronomy), which is based on multi-scale Markovian modeling. MARSIAA can be applied simultaneously to different bands. It segments an image into a user-defined number of classes, according to their surface brightness and surroundings - typically, one or two classes contain the LSB structures. We have developed an algorithm, called DetectLSB, which allows the efficient identification of LSB galaxies from among the candidate sources selected by MARSIAA. To assess the robustness of our method, the method was applied to a set of 18 B and I band images (covering 1.3 square degrees in total) of the Virgo cluster. To further assess the completeness of the results of our method, both MARSIAA, SExtractor, and DetectLSB were applied to search for (i) mock Virgo LSB galaxies inserted into a set of deep Next Generation Virgo Survey (NGVS) gri-band subimages and (ii) Virgo LSB galaxies identified by eye in a full set of NGVS square degree gri images. MARSIAA/DetectLSB recovered ~20% more mock LSB galaxies and ~40% more LSB galaxies identified by eye than SExtractor/DetectLSB. With a 90% fraction of false positives from an entirely unsupervised pipeline, a completeness of 90% is reached for sources with r_e > 3" at a mean surface brightness level of mu_g=27.7 mag/arcsec^2 and a central surface brightness of mu^0 g=26.7 mag/arcsec^2. About 10% of the false positives are artifacts, the rest being background galaxies. We have found our method to be complementary to the application of matched filters and an optimized use of SExtractor, and to have the following advantages: it is scale-free, can be applied simultaneously to several bands, and is well adapted for crowded regions on the sky.Comment: 39 pages, 18 figures, accepted for publication in A

Equivariant KK-theory of GKM bundles

Given a fiber bundle of GKM spaces, $\pi\colon M\to B$, we analyze the structure of the equivariant $K$-ring of $M$ as a module over the equivariant $K$-ring of $B$ by translating the fiber bundle, $\pi$, into a fiber bundle of GKM graphs and constructing, by combinatorial techniques, a basis of this module consisting of $K$-classes which are invariant under the natural holonomy action on the $K$-ring of $M$ of the fundamental group of the GKM graph of $B$. We also discuss the implications of this result for fiber bundles $\pi\colon M\to B$ where $M$ and $B$ are generalized partial flag varieties and show how our GKM description of the equivariant $K$-ring of a homogeneous GKM space is related to the Kostant-Kumar description of this ring.Comment: 15 page

Facility for validating technologies for the autonomous space rendezvous and docking to uncooperative targets

We present the latest advancements in the air-bearing facility installed at La Sapienza’s GN Lab in the School of Aerospace Engineering. This facility has been utilized in recent times to validate robust control laws for simultaneous attitude control and vibration active damping. The instrumentation and testbed have been restructured and enhanced to enable simulations of close proximity operations. Relative pose determination, accomplished through visual navigation as either an auxiliary or standalone system, is the first building block. Leveraging the acquired knowledge, optimal guidance and control algorithms can be tested for contactless operations (e.g. on-orbit inspection), as well as berthing and docking tasks

particle size evaluation of total mixed rations in intensive beef production systems

AbstractSamples of total mixed ration (TMR) were collected periodically in 15 beef cattle farms and submitted to a nutritional and particle size evaluation. Samples of faeces were taken and analysed for pH, consistency, colour and visually ranked for corn residues (Corn Residue Index) from 4 (totally digested) to 0 (very high presence of maize residues). Dry matter (DM), crude protein (CP), and ash content of TMR for Limousine were higher than that for Charolaise while an opposite situation was observed for crude fiber (CF). Particle size analysis of TMR showed an higher content of small ( 19.0 mm) particles in Charolaise than in Limousine TMR. From May to September a general increase of larger fractions and a reduction of the smaller ones were observed, as a consequence of empirical practices of TMR formulation during summer. Faeces characteristics did not show any difference between breeds (overall mean pH: 6.00 vs 6.13; Corn Residue Index: 2.90 vs 3.24, respectively for Charolaise a..

Temperature Chaos in Two-Dimensional Ising Spin Glasses with Binary Couplings: a Further Case for Universality

We study temperature chaos in a two-dimensional Ising spin glass with random quenched bimodal couplings, by an exact computation of the partition functions on large systems. We study two temperature correlators from the total free energy and from the domain wall free energy: in the second case we detect a chaotic behavior. We determine and discuss the chaos exponent and the fractal dimension of the domain walls.Comment: 5 pages, 6 postscript figures; added reference

Recurrent network activity drives striatal synaptogenesis

Neural activity during development critically shapes postnatal wiring of the mammalian brain. This is best illustrated by the sensory systems, in which the patterned feed-forward excitation provided by sensory organs and experience drives the formation of mature topographic circuits capable of extracting specific features of sensory stimuli1,2. In contrast, little is known about the role of early activity in the development of the basal ganglia, a phylogenetically ancient group of nuclei fundamentally important for complex motor action and reward-based learning3,4. These nuclei lack direct sensory input and are only loosely topographically organized5,6, forming interlocking feed-forward and feed-back inhibitory circuits without laminar structure. Here we use transgenic mice and viral gene transfer methods to modulate neurotransmitter release and neuronal activity in vivo in the developing striatum. We find that the balance of activity among the two inhibitory and antagonist pathways in the striatum regulates excitatory innervation of the basal ganglia during development. These effects indicate that the propagation of activity through a multi-stage network regulates the wiring of the basal ganglia, revealing an important role of positive feedback in driving network maturation

Potenciales presas zooplanctónicas (Copepoda y Appendicularia) para Engraulis anchoita en relación con las distribuciones de larvas tempranas y de desove en la región frontal patagónica (océano Atlántico sudoccidental)

We investigated the spatial distribution of the abundance, biomass and size of zooplankton (nauplii, calanoids, cyclopoids and appendicularians) in relation to the distribution of first-feeding larvae and eggs of Engraulis anchoita across the frontal system of Peninsula Valdés. Twelve samples of zooplankton and ichthyoplankton were taken with small Bongo (67 μm) and Pairovet (200 μm) nets during the spring of 2004 along two transects. The total abundance of zooplankton and the chlorophyll a concentration were higher in homogeneous waters, while total biomasses were higher in stratified waters. Temperature was negatively correlated with biological variables and was the main factor affecting the zooplankton distribution. In both transects, abundance peaks of first-feeding larvae were detected at coastal stations along with the smallest fraction of zooplankton ( < 500 μm), while the largest fraction was dominant at the external stations, coinciding with the highest egg abundance. The physical structure of this front generates different levels of food availability for first-feeding larvae. Calanoids (southern transect) and cyclopoids (northern transect) are predominant followed by nauplii and appendicularians. The biomass of zooplankton preys contributes to the carbon transfer to the upper trophic levels and is probably important for the survival and growth of anchovy larvae in this frontal system.Se investigó la distribución espacial de la abundancia, biomasa y las tallas del zooplancton (nauplii, calanoideos, ciclopoideos y apendicularias) en relación con la distribución de las larvas en estadio de primera alimentación y los huevos de Engraulis anchoita en el sistema frontal de Península Valdés. Se tomaron 12 muestras de zooplancton e ictioplancton durante la primavera de 2004 a lo largo de dos transectos, mediante una red Minibongo (67 μm) y una Pairovet (200 μm) respectivamente. La abundancia total del zooplancton y la concentración de clorofila fue mayor en aguas homogéneas, mientras que la biomasa fue mayor en aguas estratificadas. La temperatura se correlacionó negativamente con las variables biológicas siendo ésta el principal factor que afectó la distribución del zooplancton. En las estaciones costeras de ambos transectos, se encontró la mayor abundancia de larvas en coincidencia con la fracción más pequeña de zooplancton ( < 500 μm), mientras que la fracción más grande fue dominante en las estaciones externas, en coincidencia con la mayor abundancia de huevos. La estructura física de este frente genera diferente disponibilidad de alimento para las larvas siendo los calanoideos (transecto sur) y los ciclopoideos (transecto norte) predominantes, seguidos por nauplii y apendicularias. La biomasa de dicho alimento zooplanctónico podría contribuir a la transferencia de carbono a los niveles tróficos superiores y esto sería importante para la supervivencia y crecimiento de la anchoita en este sistema frontal

Associations of awareness of age-related change with emotional and physical well-being: a systematic review and meta-analysis

This is the final version. Available on open access from OUP via the DOI in this recordBACKGROUND AND OBJECTIVES: This systematic review aimed to synthesize and quantify the associations of awareness of age-related change (AARC) with emotional well-being, physical well-being, and cognitive functioning. RESEARCH DESIGN AND METHODS: We conducted a systematic review with a correlational random effects meta-analysis. We included quantitative studies, published from January 1, 2009 to October 3, 2018, exploring associations between AARC and one or more of the following outcomes: emotional well-being, physical well-being, and cognitive functioning. We assessed heterogeneity (I2) and publication bias. RESULTS: We included 12 studies in the review, 9 exploring the association between AARC and emotional well-being and 11 exploring the association between AARC and physical well-being. No study explored the association between AARC and cognitive functioning. Six articles were included in the meta-analysis. We found a moderate association between a higher level of AARC gains and better emotional well-being (r = .33; 95% CI 0.18, 0.47; p <.001; I2 = 76.01) and between a higher level of AARC losses and poorer emotional (r = -.31; 95% CI -0.38, -0.24; p < .001; I2 = 0.00) and physical well-being (r = -.38; 95% CI -0.51, -0.24; p < .001; I2 = 83.48). We found a negligible association between AARC gains and physical well-being (r = .08; 95% CI 0.02, 0.14; p < .122; I2 = 0.00). Studies were of medium to high methodological quality. DISCUSSION AND IMPLICATIONS: There is some indication that AARC gains and losses can play a role in emotional well-being and that AARC losses are associated with physical well-being. However, the number of included studies is limited and there was some indication of heterogeneity. PROSPERO REGISTRATION: CRD42018111472.University of Exeter College of Life and Environmental Sciences (School of Psychology)University of Exeter College of Medicine and Healt