Predictive Control of Autonomous Kites in Tow Test Experiments

In this paper we present a model-based control approach for autonomous flight of kites for wind power generation. Predictive models are considered to compensate for delay in the kite dynamics. We apply Model Predictive Control (MPC), with the objective of guiding the kite to follow a figure-of-eight trajectory, in the outer loop of a two level control cascade. The tracking capabilities of the inner-loop controller depend on the operating conditions and are assessed via a frequency domain robustness analysis. We take the limitations of the inner tracking controller into account by encoding them as optimisation constraints in the outer MPC. The method is validated on a kite system in tow test experiments.Comment: The paper has been accepted for publication in the IEEE Control Systems Letters and is subject to IEEE Control Systems Society copyright. Upon publication, the copy of record will be available at http://ieeexplore.ieee.or

The first INTEGRAL-OMC catalogue of optically variable sources

The Optical Monitoring Camera (OMC) onboard INTEGRAL provides photometry in the Johnson V-band. With an aperture of 50 mm and a field of view of 5deg x 5deg, OMC is able to detect optical sources brighter than V~18, from a previously selected list of potential targets of interest. After more than nine years of observations, the OMC database contains light curves for more than 70000 sources (with more than 50 photometric points each). The objectives of this work have been to characterize the potential variability of the objects monitored by OMC, to identify periodic sources and to compute their periods, taking advantage of the stability and long monitoring time of the OMC. To detect potential variability, we have performed a chi-squared test, finding 5263 variable sources out of an initial sample of 6071 objects with good photometric quality and more than 300 data points each. We have studied the periodicity of these sources using a method based on the phase dispersion minimization technique, optimized to handle light curves with very different shapes.In this first catalogue of variable sources observed by OMC, we provide for each object the median of the visual magnitude, the magnitude at maximum and minimum brightness in the light curve during the window of observations, the period, when found, as well as the complete intrinsic and period-folded light curves, together with some additional ancillary data.Comment: Accepted by Astronomy & Astrophysics; 13 pages, 16 figures. Figures' resolution has been degraded to fit astro-ph constraint

State Estimation for Kite Power Systems with Delayed Sensor Measurements

We present a novel estimation approach for airborne wind energy systems with ground-based control and energy generation. The estimator fuses measurements from an inertial measurement unit attached to a tethered wing and position measurements from a camera as well as line angle sensors in an unscented Kalman filter. We have developed a novel kinematic description for tethered wings to specifically address tether dynamics. The presented approach simultaneously estimates feedback variables for a flight controller as well as model parameters, such as a time-varying delay. We demonstrate the performance of the estimator for experimental flight data and compare it to a state-of-the-art estimator based on inertial measurements

Variational Estimates using a Discrete Variable Representation

The advantage of using a Discrete Variable Representation (DVR) is that the Hamiltonian of two interacting particles can be constructed in a very simple form. However the DVR Hamiltonian is approximate and, as a consequence, the results cannot be considered as variational ones. We will show that the variational character of the results can be restored by performing a reduced number of integrals. In practice, for a variational description of the lowest n bound states only n(n+1)/2 integrals are necessary whereas D(D+1)/2 integrals are enough for the scattering states (D is the dimension of the S matrix). Applications of the method to the study of dimers of He, Ne and Ar, for both bound and scattering states, are presented.Comment: 30 pages, 7 figures. Minor changes (title modified, typos corrected, 1 reference added). To be published in PR

Activity Identification and Local Linear Convergence of Douglas--Rachford/ADMM under Partial Smoothness

Convex optimization has become ubiquitous in most quantitative disciplines of science, including variational image processing. Proximal splitting algorithms are becoming popular to solve such structured convex optimization problems. Within this class of algorithms, Douglas--Rachford (DR) and alternating direction method of multipliers (ADMM) are designed to minimize the sum of two proper lower semi-continuous convex functions whose proximity operators are easy to compute. The goal of this work is to understand the local convergence behaviour of DR (resp. ADMM) when the involved functions (resp. their Legendre-Fenchel conjugates) are moreover partly smooth. More precisely, when both of the two functions (resp. their conjugates) are partly smooth relative to their respective manifolds, we show that DR (resp. ADMM) identifies these manifolds in finite time. Moreover, when these manifolds are affine or linear, we prove that DR/ADMM is locally linearly convergent. When $J$ and $G$ are locally polyhedral, we show that the optimal convergence radius is given in terms of the cosine of the Friedrichs angle between the tangent spaces of the identified manifolds. This is illustrated by several concrete examples and supported by numerical experiments.Comment: 17 pages, 1 figure, published in the proceedings of the Fifth International Conference on Scale Space and Variational Methods in Computer Visio

A Case Study on Critical Consciousness in Dual Language Bilingual Education

This ethnographic case study explores how dual language bilingual education (DLBE) educators understand, enact, and acquire their perceptions of and tools to educate for critical consciousness, especially in relation to culturally and linguistically diverse students who are often labeled as “emergent bilinguals”, “native Spanish speakers” and/or “ELLs”. The present study responds to Cervantes-Soon’s (2014) call for attention to critical consciousness in DLBE. Hence, the purpose is to gain insight into the role of critical consciousness in DLBE educators’ work. The findings inform practitioners’ as well as scholars’ work, and lend insight for those who study critical consciousness, social justice in education, and/or DLBE programming

Parasites from freshwater fishes and Mollusca; a new species of Capillaria from the minnow and five new Cercariae from Limnaea

Since the discovery of sporocysts and rediae "by Steenstrup in 1842, the study of the life histories of different Trematodes has received much attention by investigators, for instance Wagener in 1857, leuckart in 1882, Thomas in 1883, Heckert in 1889, Greutzberg in 1890 and Looss in recent times. It was from the observations of these workers that the life cycle of Trematodes was put on a firm basis. But no real importance was attached to the study of miracidia, sporocysts, rediaeand cercariae until after the classical work of Thomas in 1883, which resulted in a thorough explanation of the life history of the liver fluke and its transmission from sheep to sheep.Since 1883 numerous investigations have been carried out from the economical and medical point of view, and the bulk of the contributions to the knowledge of cerca.riae consists of the results of observations and experiments on the cercariee of the Trematodes infecting man and the domestic animals Particular attention was paid to the different intermediate hosts and the conditions under which they are capable of causing the infection of the definitive hosts.A serious study of the organisation of cercariae was long neglected and in spite of the numerous cercariae described by many investigators, it is impossible to identify many of the species correctly. It was only after the study of the cercariae of the Schistosomidae infecting man that the study of the morphology and histology of other cercariae was adequately undertaken, and authors began to attach importance to features of the internal organisation, which may throw light on the structure of the adult. The systems which have been carefully studied are the alimentary tract, the excretory and genital systems, and specific differences were observed even among cercariae closely resembling one another. Certain glands in the body have also been observed, and have proved in many cases to play an important part in the process of infection of the definitive host.If the external and internal structures of a cercaria be considered, we may divide the characters into two sets:(A) 'Those structures such as the suckers, the alimentary tract, the excretorysystem, the genital system, and some parenchymatous cells which form the basis or are the miniatures of the corresponding adult structures,(B) Those structures such as tails, spines, processes, stylets, eye spots, salivary glands, cystogenous cells and parenchymatous cells,which are purely larval structures and are not carried over to the adult. The structures belonging to the former group are relatively well known but in the case of the larval structures there is much yet to be explained.What are termed salivary glands may have the same structure but different functions in different cases. The cystogenous cells are distinguishable from parenchymatous cells by possessing larger nuclei poor in chromatin, and cytoplasm which may contain obvious granules or may be faintly granular, but their function is not always demonstrable. Lastly the parenchymatous cells are indistinguishable from other cells such as those surrounding the nerve ganglia, those under the cuticle, which have received the name of cuticular cells and from cells which are destined to give rise to other structures such as vitelline glands. Looss emphasized the fact that thesecells are at first indistinguishable cytologically and maintained that many of these mesodermal cells remain findifferentiated for a considerable time. There is also reason to believe that some cells in the parenchyma form the basis of other structures such as the excretory system, for the collecting ducts are not bounded by cellular walls, but are merely lumina among certain cells. Certain other parenchymatous cells both in the body and in the tail of some cerc&riae are more vacuolated and distended and their function appears to be that of buoyancy