We present LoTUS, a novel Machine Unlearning (MU) method that eliminates the influence of training samples from pre-trained models, avoiding retraining from scratch. LoTUS smooths the prediction probabilities of the model up to an information-theoretic bound, mitigating its overconfidence stemming from data memorization. We evaluate LoTUS on Transformer and ResNet18 models against eight baselines across five public datasets. Beyond established MU benchmarks, we evaluate unlearning on ImageNet1k, a large-scale dataset, where retraining is impractical, simulating real-world conditions. Moreover, we introduce the novel Retrain-Free Jensen-Shannon Divergence (RF-JSD) metric to enable evaluation under real-world conditions. The experimental results show that LoTUS outperforms state-of-the-art methods in terms of both efficiency and effectiveness. Code: https://github.com/cspartalis/LoTUS.

Abstract Adversarial attacks pose a threat to neural networks, requiring robust methods to mitigate them. Adversarial Training has emerged as a promising approach; however, its practical application in real-world deep learning systems is hindered by the trade-offs between efficiency and robustness, as optimizing for one aspect may come at cost of the other. This paper presents a comprehensive investigation into the impact of different Adversarial Training approaches and model types on the robustness of adversarially trained models, while considering the dynamic trade-offs involved. Leveraging our previously published method, Delayed Adversarial Training with Non-Sequential Adversarial Epochs – DATNS, we conduct extended empirical analyses through new experiments to effectively balance these trade-offs and navigate the interplay between efficiency and robustness, as well as catastrophic forgetting and interpretability. By providing our insights on the discussed trade-offs this research aims to enable the development of more efficient, robust, and interpretable models against adversarial attacks.

Adversarial Training (AT) has so far been considered as the most effective approach for building robust computer vision architectures that can adequately handle adversarial attacks. However, its high complexity, rising from the need to repeatedly generate attacks against image batches over training epochs, has been a controlling factor to its generalized use. Therefore, to date, AT has only been used for training on vanilla datasets, casting doubt on how soon it can be applied to real world computer vision systems in safety critical domains. Few researchers have to a certain extent addressed the issue by proposing AT variations which have moderately improved the complexity. Extending these advances, this work explores simple yet effective ways to further improve the complexity of AT in terms of training time. Specifically, it is explored through this work whether a) training sequential adversarial epochs and b) attacking the entire dataset during adversarial epochs are necessary for a robust learned model.

Convolutional Neural Networks (CNNs) have recently been introduced for addressing copy-move forgery detection (CMFD). However, current CMFD CNN-based approaches have insufficient performance commitment regarding the localization of the positive class. In this paper, this issue is explored by considering both linear and nonlinear interactions between pixels. A nonlinear Inception module based on second-order Volterra kernels is proposed, in order to ameliorate the results of a state-of-the-art CMFD architecture. The outcome of this work shows that a combination of linear and nonlinear convolution kernels can make the input foreground and background pixels more separable. The proposed approach is evaluated on CASIA and CoMoFoD, two publicly available CMFD datasets, and results to an improved positive class localization performance. Moreover, the findings of the proposed method imply that the nonlinear Inception module stimulates immense robustness against miscellaneous post processing attacks.

It is a challenge to aggregate and analyze data from heterogeneous social media sources not only for businesses and organizations but also for Law Enforcement Agencies. The latter’s core objectives are to monitor criminal and terrorist related activities and to identify the ”key players” in various networks. In this paper, a framework for homogenizing and exploiting data from multiple sources is presented. Moreover, as part of the framework, an ontology that reflects today’s social media perceptions is introduced. Data from multiple sources is transformed into a labeled property graph and stored in a graph database in a homogenized way based on the proposed ontology. The result is a cross-source analysis system where end-users can explore different scenarios and draw conclusions through a library of predefined query placeholders that focus on forensic investigation. The framework is evaluated on the Stormfront dataset, a radical right, web community. Finally, the benefits of applying the proposed framework to discover and visualize the relationships between the Stormfront profiles are presented.

Driven by the needs of customers and industry, online fashion search and analytics are recently gaining much attention. As fashion is mostly expressed by visual content, the analysis of fashion images in online social networks is a rich source of possible insights on evolving trends and customer preferences. Although a plethora of visual content is available, the modeling of clothes’ physics and movement, the implicit semantics in fashion designs, and the subjectivity of their interpretation pose difficulties to fully automated solutions for fashion search and analysis. In this article, we present the design and evaluation of a crowd-powered system for fashion similarity search from Twitter, supporting trend analysis for fashion professionals. The system enables fashion similarity search based on specific human-based similarity criteria. This is achieved by implementing a novel machine--crowd workflow that supports complex tasks requiring highly subjective judgments where multiple true solutions may coexist. We discuss how this leads to a novel class of crowd-powered systems for which the output of the crowd is not used to verify the automatic analysis but is the desired outcome. Finally, we show how this kind of crowd involvement enables a novel kind of similarity search and represents a crucial factor for the acceptance of system results by the end user.

Content searching and downloading are the two dominant actions of the Internet users today, despite the fact that the Internet was not originally architected to serve such actions. Content Centric Networking is the new trend in the research community to build network architectures that route content by name and not by the host's network address so as to efficiently deal with content persistence, availability and authenticity issues. In this work we propose an extension to the Content Centric Network protocol in order to support content search as a native process of the network. By using object descriptors to represent the actual content objects and integrate these descriptors in the network protocol we manage to search and retrieve content from the network not only by name but also by the content itself. In this approach, searching for information is a process distributed to the reachable network. Moreover, content aggregation is handled by the end user and not by content aggregation portals, thematic content search engines or information curators. By doing so, search is not any more an application but part of the network and can pave the way for many novel applications which have never been thought until today.

In this paper a comparative study of three ground traffic surveillance systems for airports based on different sensing technologies is presented. The first two solutions are based on video-based surveillance, while the third one is based on signal-based surveillance. More specifically, the first solution employs a network of smart cameras, whereas the second utilizes multiple autonomous tracking units to capture and process images from one or more pre-calibrated cameras. The third solution is based on a novel magnetic sensing technology, which detects ferromagnetic objects such as vehicle motors, aircraft engines and landing gears through their deformation of the Earthpsilas magnetic field. Evaluation and analysis of the performance of these systems, based on real test results in different European airports are presented. The proposed systems are flexible, scalable and suitable for a broad field of monitoring and surveillance applications.