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SUMMARYThis paper presents a multi-scale framework for the failure of periodic quasi-brittle thin planar shells. The failure behavior of textured or periodic heterogeneous materials is strongly influenced by their mesostructure. Their periodicity and the quasi-brittle nature of their constituents result in complex behaviors such as damage-induced anisotropy properties with localization of damage, which are difficult to model by means of macroscopic closed-form constitutive laws. A computational homogenization procedure is used for the in-plane and out-of-plane behavior of such planar shells, and is combined with an acoustic tensor-based failure detection adapted to shell kinematics to detect the structural-scale failure. Based on an assumption of single period failure, the localization of damage at the structural scale is represented by means of mesostructurally informed embedded strong discontinuities incorporated in the macroscopic shell description. A new enhanced scale transition is outlined for shell failure, based on an approximate energy consistency argument to objectively upscale the energy dissipation. The corresponding multi-scale framework results are compared with direct fine-scale modeling results used as a reference for the case of masonry, showing good agreement in terms of the load-bearing capacity, of failure mechanisms and of associated energy dissipation.

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The Global Wheat Head Detection (GWHD) dataset was created in 2020 and has assembled 193,634 labelled wheat heads from 4700 RGB images acquired from various acquisition platforms and 7 countries/institutions. With an associated competition hosted in Kaggle, GWHD_2020 has successfully attracted attention from both the computer vision and agricultural science communities. From this first experience, a few avenues for improvements have been identified regarding data size, head diversity, and label reliability. To address these issues, the 2020 dataset has been reexamined, relabeled, and complemented by adding 1722 images from 5 additional countries, allowing for 81,553 additional wheat heads. We now release in 2021 a new version of the Global Wheat Head Detection dataset, which is bigger, more diverse, and less noisy than the GWHD_2020 version.

Introduction. Precision Livestock Farming (PLF) is spreading rapidly in intensive cattle farms. It is based on the monitoring of individuals using different kinds of sensors. Applied to grazing animals, PLF is mainly based on the recording of three parameters: the location, the posture and the movements of the animal. Until now, several techniques have been used to discriminate grazing and ruminating behaviors with accuracies over 90% on average, when compared to observations, providing valuable tools to improve the management of pasture and grazing animals. However, bites and jaw movements are still overlooked, even though they are of utmost importance to assess the animal grazing strategies for various pasture types and develop future techniques allowing better estimation of their intake. Literature. The goal of this review is to explore the possibility of monitoring the individual jaw movements and the differentiation of bites in grazing animals. For this purpose, (1) the mechanisms of forage intake in cattle are explained briefly in order to understand the movements performed by the cow, especially during grazing, (2) the various sensors that have been proposed to monitor jaw movements of ruminants such as mechanical sensors (pressure sensors), acoustic sensors (microphone) and electromyography sensors are compared and (3) finally the relationship between jaw movements, biting behavior and forage intake is discussed. Conclusions. The review clearly demonstrated the abilities of mechanical, acoustic and electromyography sensors to classify the difference types of jaw movements. However, it also indicated a wide range of accuracies and different observation windows required to reach these accuracies when compared to the observed movement. This classification purpose could lead to a better detection of more specific behavior, e.g. bite detection, and their exact location on pasture.

This paper presents a computational homogenisation-based technique for flexural effects in textile reinforced composite planar shells. An homogenisation procedure is used for the in-plane and the out-of-plane behaviour of three-dimensional woven composite shells taking the in-plane periodicity of the material into account while relaxing any periodicity tying in the thickness direction. Several types of damage (matrix or reinforcement cracking, delamination, ...) can appear in a composite material. In this paper, material non-linear computations are used to assess the importance of bending on the risk for delamination at the reinforcement/matrix interface. The normal and tangential stresses at the interface are computed and a simplified criterion for delamination is used for this purpose. The effect of flexural loading on the stress components responsible for a potential delamination failure mode at the interface is analysed. The values of interface stresses obtained by means of flexural homogenisation are compared with 3D homogenisation results using periodicity constraints along the thickness direction, and compared qualitatively with experimental facts available from the litterature. The importance for taking flexural effects into account properly is emphasized. * Corresponding author. Tel. : +32 2 650 27 42 ; Fax : +32 2 650 27 82 On leave at

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