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Implied Integrality in Mixed-Integer Optimization
No full textImplied-integer detection is a well-known presolving technique that is used by many Mixed-Integer Linear Programming solvers. Informally, a variable is said to be implied integer if its integrality is enforced implicitly by integrality of other variables and the constraints of a problem. In this paper we formalize the definition of implied integrality by taking a polyhedral perspective. Our main result characterizes implied integrality as occurring when a subset of integer variables is fixed to integer values and the polyhedron on the remaining variables is integral. While integral polyhedra are well-understood theoretically, existing detection methods infer implied integrality only for one variable at a time. We introduce new detection methods based on the detection of integral polyhedra, extending existing techniques to multiple variables. Additionally, we discuss the computational complexity of recognizing implied integers. We conduct experiments using a new detection method that uses totally unimodular submatrices to identify implied integrality. For the MIPLIB 2017 collection dataset our results indicate that, on average, 18.8% of the variables are classified as implied integer after presolving, compared to just 3.3% identified by state-of-the-art techniques. We are able to reduce the average percentage of variables whose integrality needs to be enforced after presolving from 70.2% to 59.0%.</p
Joint Beamforming for Multi-user Multi-target FD ISAC System:A Hybrid GRQ-GA Approach
No full textIn this paper, we consider a full-duplex (FD) Inte-grated Sensing and Communication (ISAC) system, in which the base station (BS) performs downlink and uplink communications with multiple users while simultaneously sensing multiple targets. In the scope of this work, we assume a narrowband and static scenario, aiming to focus on the beamforming and power allocation strategies. We propose a joint beamforming strategy for designing transmit and receive beamformer vectors at the BS. The optimization problem aims to maximize the communication sum-rate, which is critical for ensuring high-quality service to users, while also maintaining accurate sensing performance for detection tasks and adhering to maximum power constraints for efficient resource usage. The optimal receive beamformers are first derived using a closed-form Generalized Rayleigh Quotient (GRQ) solution, reducing the variables to be optimized. Then, the remaining problem is solved using floating-point Genetic Algorithms (GA). The numerical results show that the proposed GA-based solution demonstrates up to a 98% enhancement in sum-rate compared to a baseline half-duplex ISAC system and provides better performance than a benchmark algorithm from the literature. Additionally, it offers insights into sensing performance effects on beam patterns as well as communication-sensing trade-offs in multi-target scenarios.</p
Ceramic Nanofiltration Membranes:Creating Nanopores by Calcination of Atmospheric-Pressure Molecular Layer Deposition Grown Titanicone Layers
Get PDFCeramic membrane technology, whether applied as a stand-alone separation technology or in combination with energy-intensive approaches like distillation, is a promising solution for lower energy alternatives with minimal carbon footprints. To improve the separation of solutes in the nanofiltration range from industrial wastewater streams, ceramic nanofiltration (NF) membranes with reproducible sub-nanometre pore sizes are required. To achieve this, the emerging technique of molecular layer deposition (MLD) is employed to develop ceramic NF membranes, and its efficiency and versatility make it a powerful tool for preparing uniform nanoscale high-porosity membranes. Our work, which involved vapor-phase titanium tetrachloride as a precursor and ethylene glycol as a co-reactant, followed by calcination in air at 350 °C, resulted in NF membranes with pore sizes (radii) around ~0.8 ± 0.1 nm and a demineralized water permeability of 13 ± 1 L·m−2·h−1·bar−1.The high-water flux with >90% rejection of polyethylene glycol molecules with a molecular size larger than 380 ± 6 Dalton indicates the efficiency of the MLD technique in membrane functionalization and size-selective separation processes, and its potential for industrial applications.</p
Policy relevance of IPCC reports for the Sustainable Development Goals and beyond
Get PDFClimate change and sustainability linkages provide opportunities to develop and implement synergistic strategies for climate actions and achieve Sustainable Development Goals (SDGs). Thus, we synthesize the coverage of SDGs in the IPCC's fifth and sixth assessment reports at a target level. Based on this reflection, we propose the seventh assessment cycle of the IPCC to cover SDGs holistically, using a systematic approach, breaking the Working Group silos, and contributing to the post-2030 agenda.</p
Enhancing Biomedical Literature Retrieval with Level of Evidence and Bio-Concepts:A Comparative User Study
Get PDFMost traditional medical search engines rely on similarity-based retrieval between the user s query and document content, ignoring important contextual aspects, such as the quality of evidence and specific biomedical concepts.Addressing these limitations,we developed WisPerMed, a medical search engine that enhances search efficiency by incorporating Level of Evidence (LoE) and bio-concepts into both the ranking process and the user interface. This study compares the performance of WisPerMed to PubMed through a user study involving 131 medical experts. Our findings indicate that WisPerMed significantly reduces the number of queries needed and the time spent on searches, with large effect sizes compared to PubMed (0.822 and 0.551, respectively). The integration of LoE and bio-concepts not only improves the ranking of relevant and authoritative articles but also facilitates their identification through enhanced GUI elements. These results highlight the potential of WisPerMed to enhance search efficiency in clinical and research settings, ultimately supporting faster and more accurate access to medical knowledge .</p
Knowing Better, Doing Better: The Role Of Actual And Perceived Knowledge Of Self-Protective Behaviour On Protection Motivation
Get PDFIn an era characterised by increasing cyber threats, there is a pressing need to gain a deeper understanding of how to enhance digital resilience at the individual level. In this study, we compared the role of actualknowledge with individuals’ perceived knowledge, and the influence on the intentions to engage in self-protective behaviour. Participants (N = 222) completed an online questionnaire, which included an actual knowledge test focusing on protection measures and items measuring constructs of ProtectionMotivation Theory. Our regression analyses showed that actual knowledge is a predictor to engage in self-protective behaviour, with a stronger influence than perceived knowledge. Both actual and perceived knowledge are vital for self-protective behaviour, however, they activate different types of efficacy. Actualknowledge is a stronger predictor of response efficacy, whereas perceived knowledge better predicts self-efficacy. We explored implications for intervention and future research in the discussion, by highlighting the need for prioritising knowledge dissemination, increasing user confidence, and the effectiveness of interventions. This paper is a substantial adaptation of a previous conference paper (Bluhm et al., 2025)
Training Diagonal Linear Networks with Stochastic Sharpness-Aware Minimization
Get PDFWe analyze the landscape and training dynamics of diagonal linear networks in a linear regression task, with the network parameters being perturbed by small isotropic normal noise. The addition of such noise may be interpreted as a stochastic form of sharpness-aware minimization (SAM) and we prove several results that relate its action on the underlying landscape and training dynamics to the sharpness of the loss. In particular, the noise changes the expected gradient to force balancing of the weight matrices at a fast rate along the descent trajectory. In the diagonal linear model, we show that this equates to minimizing the average sharpness, as well as the trace of the Hessian matrix, among all possible factorizations of the same matrix. Further, the noise forces the gradient descent iterates towards a shrinkage-thresholding of the underlying true parameter, with the noise level explicitly regulating both the shrinkage factor and the threshold
Stakeholder Perspectives on Microgrid Interoperability in Energy Access
Get PDFInteroperability is critical for the sustainability and scalability of decentralized energy systems. It facilitates self-coordination, component replacement, system expansion, upgrades, and integration with other systems, including the main grid. Despite its importance, achieving interoperability in the energy access sector remains a challenge, as stakeholders have diverse perspectives on approaches and strategies to achieve interoperability, creating further complexity. This study explores stakeholder perspectives on how microgrid interoperability can be achieved in the context of energy access, using Indonesia as a case study. To capture the diversity and subjectivity of expert opinions, the study employs the Q methodology, marking the first application of this method to the topic of interoperability. The study advances the theoretical understanding of interoperability in decentralized energy systems by revealing four distinct stakeholder perspectives, namely (1) Harmonization Promoters, (2) Industry Allies, (3) Tech Proponents, and (4) Public Advocates. Although there are some areas of consensus, stakeholders differ in their views on standardization, technical features, and stakeholder roles. These differences highlight the competing priorities that influence decision making on approaches to interoperability that balance technical, regulatory, and market considerations. This study provides practical insights for developing more inclusive and effective interoperability strategies, supported by empirical evidence derived from primary data gathered from relevant stakeholders.</p
Homomorphism tensors and linear equations
No full textLovász (1967) showed that two graphs G and H are isomorphic if and only if they are homomorphism indistinguishable over the class of all graphs, i.e. for every graph F, the number of homomorphisms from F to G equals the number of homomorphisms from F to H. Recently, homomorphism indistinguishability over restricted classes of graphs such as bounded treewidth, bounded treedepth and planar graphs, has emerged as a surprisingly powerful framework for capturing diverse equivalence relations on graphs arising from logical equivalence and algebraic equation systems. In this paper, we provide a unified algebraic framework for such results by examining the linear-algebraic structure of tensors counting homomorphisms from labelled graphs. The existence of certain linear transformations between such homomorphism tensor subspaces can be interpreted both as homomorphism indistinguishability over a graph class and as feasibility of an equational system. Following this framework, we obtain characterisations of homomorphism indistinguishability over several natural graph classes, namely trees of bounded degree, graphs of bounded pathwidth (answering a question of Dell et al. (2018)), and graphs of bounded treedepth.</p
To Repair or not to Repair? Disclosing the Subject in Technical Mediation
Get PDFThis paper aims to develop a more comprehensive account of subjectivity in human-technology relations. Our argument unfolds in two stages. First, we contend that classical mediation theory falls short in addressing subjectivity, as it remains confined to functionalist and instrumentalist perspectives. Rather than rejecting postphenomenology, we seek to renew and deepen it by reconnecting it to its phenomenological roots as envisioned by Don Ihde. Second, we extend mediation theory through what we call the “technology lifecycle.” This framework retains attention to functionality and design while explicitly incorporating two additional and equally important dimensions: breakdown and maintenance. To adequately grasp these moments, we draw on a Ricoeurian interpretation of the dynamic between the designer-user subject and the “subject without technology,” who is primarily concerned with maintenance and care. By revisiting and expanding postphenomenology in this way, we aim to offer a richer and more nuanced understanding of the subject of technology—the central concern of this paper.</p