This paper introduces the first public large-scale, long-span dataset with sea turtle photographs captured in the wild -$SeaTurtleID2022$. The dataset contains 8729 photographs of 438 unique individuals collected within 13 years, making it the longest-spanned dataset for animal re-identification. Each photograph includes various annotations, e.g., identity, encounter timestamp, and body parts segmentation masks. Instead of a standard ’’random" split, the dataset allows for two realistic and ecologically motivated splits: (i) time-aware: a closed-set with training, validation, and test data from different days/years, and (ii) open-set: with new unknown individuals in test and validation sets. We show that time-aware splits are essential for benchmarking methods for re-identification, as random splits lead to performance overestimation. Furthermore, a baseline instance segmentation and re-identification performance over various body parts is provided. At last, an end-to-end system for sea turtle re-identification is proposed and evaluated. The proposed system based on Hybrid Task Cascade for head instance segmentation and ArcFace-trained feature-extractor achieved an accuracy of 86.8%.

In this paper, we present WildlifeDatasets – an open-source toolkit intended primarily for ecologists and computer-vision / machine-learning researchers. The WildlifeDatasets is written in Python, allows straightforward access to publicly available wildlife datasets, and provides a wide variety of methods for dataset pre-processing, performance analysis, and model fine-tuning. We show-case the toolkit in various scenarios and baseline experiments, including, to the best of our knowledge, the most comprehensive experimental comparison of datasets and methods for wildlife re-identification, including both local descriptors and deep learning approaches. Furthermore, we provide the first-ever foundation model for individual re-identification within a wide range of species – MegaDescriptor – that provides state-of-the-art performance on animal re-identification datasets and outperforms other pre-trained models such as CLIP and DINOv2 by a significant margin. To make the model available to the general public and to allow easy integration with any existing wildlife monitoring applications, we provide multiple MegaDescriptor flavors (i.e., Small, Medium, and Large) through the HuggingFace hub.

Maximum torque per current (MTPA) and other optimal curves are well-known for three-phase machines. Since multiphase machines dispose by more degrees of freedom than their three-phase counterparts, the solution is much more complicated and a variety of regimes can be found. In this paper, optimal current setpoints for five-phase synchronous machines are analyzed. Besides the first harmonic, the optimization includes also the third harmonic, used for both torque enhancement and waveform shaping. It is shown that the MTPA curves, field weakening (FW) and maximum current (MC) regions have an inner structure with multiple regimes. This variety comes from the phase voltage and phase current limits that yield optimizing waveforms containing multiple peaks (peak shaving). A taxonomy of these regimes is provided, and their mutual relations are demonstrated on a case study machine. The optimal current setpoints in their waveforms are analyzed in selected operating points.

We propose a novel method for creating adversarial examples. Instead of perturbing pixels, we use an encoder-decoder representation of the input image and perturb intermediate layers in the decoder. This changes the high-level features provided by the generative model. Therefore, our perturbation possesses semantic meaning, such as a longer beak or green tints. We formulate this task as an optimization problem by minimizing the Wasserstein distance between the adversarial and initial images under a misclassification constraint. We employ the projected gradient method with a simple inexact projection. Due to the projection, all iterations are feasible, and our method always generates adversarial images. We perform numerical experiments on the MNIST and ImageNet datasets in both targeted and untargeted settings. We demonstrate that our adversarial images are much less vulnerable to steganographic defence techniques than pixel-based attacks. Moreover, we show that our method modifies key features such as edges and that defence techniques based on adversarial training are vulnerable to our attacks.

Many efficient algorithms have been designed to recover Nash equilibria of various classes of finite games. Special classes of continuous games with infinite strategy spaces, such as polynomial games, can be solved by semidefinite programming. In general, however, continuous games are not directly amenable to computational procedures. In this contribution, we develop an iterative strategy generation technique for finding a Nash equilibrium in a whole class of continuous two-person zero-sum games with compact strategy sets. The procedure, which is called the double oracle algorithm, has been successfully applied to large finite games in the past. We prove the convergence of the double oracle algorithm to a Nash equilibrium. Moreover, the algorithm is guaranteed to recover an approximate equilibrium in finitely-many steps. Our numerical experiments show that it outperforms fictitious play on several examples of games appearing in the literature. In particular, we provide a detailed analysis of experiments with a version of the continuous Colonel Blotto game.