Energy
Operator Inference Aware Quadratic Manifolds with Isotropic Reduced Coordinates for Nonintrusive Model Reduction
Schwerdtner, Paul, Mohan, Prakash, Bessac, Julie, de Frahan, Marc T. Henry, Peherstorfer, Benjamin
Learning reduced models from data in a nonintrusive fashion is an important problem in science and engineering [1, 2, 3]. A typical approach is to first learn an encoder-decoder pair, embed the training snapshot trajectories with the learned encoder, and then fit a reduced dynamical-system model to the embedded trajectories. However, the decomposition of the training process into first learning an encoder-decoder pair for the embedding and only sub-sequentially learning a model of the dynamics typically means that the encoder-decoder pair are trained with the objective of accurately approximating the training data, rather than taking the reduced-model prediction error into account. Thus, the encoder-decoder pair can overfit to achieving a low reconstruction error on the training data by learning embeddings of the snapshot trajectories that are non-smooth, which means that learning a reduced model can become challenging. Correspondingly, it has been observed that learning embeddings and models together can be beneficial; see, e.g., [4, 5, 6, 7]. In the context of intrusive model reduction with linear approximations, there is work that optimizes the reduced basis with respect to the model prediction error [8], quantities of interest [9], and to achieve stability [10]; however, we focus here on the setting of nonintrusive model reduction and nonlinear approximations.
ACCESS-AV: Adaptive Communication-Computation Codesign for Sustainable Autonomous Vehicle Localization in Smart Factories
Bhattacharjya, Rajat, Sarkar, Arnab, Kool, Ish, Baidya, Sabur, Dutt, Nikil
Autonomous Delivery Vehicles (ADVs) are increasingly used for transporting goods in 5G network-enabled smart factories, with the compute-intensive localization module presenting a significant opportunity for optimization. We propose ACCESS-AV, an energy-efficient Vehicle-to-Infrastructure (V2I) localization framework that leverages existing 5G infrastructure in smart factory environments. By opportunistically accessing the periodically broadcast 5G Synchronization Signal Blocks (SSBs) for localization, ACCESS-AV obviates the need for dedicated Roadside Units (RSUs) or additional onboard sensors to achieve energy efficiency as well as cost reduction. We implement an Angle-of-Arrival (AoA)-based estimation method using the Multiple Signal Classification (MUSIC) algorithm, optimized for resource-constrained ADV platforms through an adaptive communication-computation strategy that dynamically balances energy consumption with localization accuracy based on environmental conditions such as Signal-to-Noise Ratio (SNR) and vehicle velocity. Experimental results demonstrate that ACCESS-AV achieves an average energy reduction of 43.09% compared to non-adaptive systems employing AoA algorithms such as vanilla MUSIC, ESPRIT, and Root-MUSIC. It maintains sub-30 cm localization accuracy while also delivering substantial reductions in infrastructure and operational costs, establishing its viability for sustainable smart factory environments.
Bipedalism for Quadrupedal Robots: Versatile Loco-Manipulation through Risk-Adaptive Reinforcement Learning
Zhang, Yuyou, Corcodel, Radu, Zhao, Ding
Loco-manipulation of quadrupedal robots has broadened robotic applications, but using legs as manipulators often compromises locomotion, while mounting arms complicates the system. To mitigate this issue, we introduce bipedalism for quadrupedal robots, thus freeing the front legs for versatile interactions with the environment. We propose a risk-adaptive distributional Reinforcement Learning (RL) framework designed for quadrupedal robots walking on their hind legs, balancing worst-case conservativeness with optimal performance in this inherently unstable task. During training, the adaptive risk preference is dynamically adjusted based on the uncertainty of the return, measured by the coefficient of variation of the estimated return distribution. Extensive experiments in simulation show our method's superior performance over baselines. Real-world deployment on a Unitree Go2 robot further demonstrates the versatility of our policy, enabling tasks like cart pushing, obstacle probing, and payload transport, while showcasing robustness against challenging dynamics and external disturbances.
A Comparative Study of OpenMP Scheduling Algorithm Selection Strategies
Korndörfer, Jonas H. Müller, Mohammed, Ali, Eleliemy, Ahmed, Guilloteau, Quentin, Krummenacher, Reto, Ciorba, Florina M.
Scientific and data science applications are becoming increasingly complex, with growing computational and memory demands. Modern high performance computing (HPC) systems provide high parallelism and heterogeneity across nodes, devices, and cores. To achieve good performance, effective scheduling and load balancing techniques are essential. Parallel programming frameworks such as OpenMP now offer a variety of advanced scheduling algorithms to support diverse applications and platforms. This creates an instance of the scheduling algorithm selection problem, which involves identifying the most suitable algorithm for a given combination of workload and system characteristics. In this work, we explore learning-based approaches for selecting scheduling algorithms in OpenMP. We propose and evaluate expert-based and reinforcement learning (RL)-based methods, and conduct a detailed performance analysis across six applications and three systems. Our results show that RL methods are capable of learning high-performing scheduling decisions, although they require significant exploration, with the choice of reward function playing a key role. Expert-based methods, in contrast, rely on prior knowledge and involve less exploration, though they may not always identify the optimal algorithm for a specific application-system pair. By combining expert knowledge with RL-based learning, we achieve improved performance and greater adaptability. Overall, this work demonstrates that dynamic selection of scheduling algorithms during execution is both viable and beneficial for OpenMP applications. The approach can also be extended to MPI-based programs, enabling optimization of scheduling decisions across multiple levels of parallelism.
$K^4$: Online Log Anomaly Detection Via Unsupervised Typicality Learning
Chen, Weicong, Singh, Vikash, Rahmani, Zahra, Ganguly, Debargha, Hariri, Mohsen, Chaudhary, Vipin
--Log anomaly detection (LogAD) is crucial for identifying failures and threats in large-scale computing and cyberin-frastructure systems. However, most existing LogAD approaches suffer from key limitations: they depend on slow and error-prone log parsing, employ tightly coupled end-to-end pipelines, often require supervision for improved detection performance, and rely on flawed single-pass evaluation protocols that fail to reflect the temporal dynamics of real-world online detection. These issues significantly hinder scalability, adaptability, and the practical deployment of solutions. These descriptors inform lightweight, modular detectors, including KDE, GMM, OCSVM, and a new adaptation of DeepSVDD, which enables efficient and accurate anomaly scoring without relying on structured formats or log representation retraining. T o support realistic deployment scenarios, we also propose a principled chunk-based evaluation protocol that mimics online log ingestion, alleviates the performance overestimation and dataset undercoverage issues of prior single-pass evaluations, and enables reproducible benchmarking across datasets with varying anomaly densities. Using this setup, we conduct over 125,000 experiments across three real-world datasets (HDFS, BGL, Thunderbird), six pre-trained embedding models, four detectors, and multiple training and log sampling configurations. Logs are essential artifacts in computing systems, recording the operational behavior of applications, kernels, and user activities. This work was supported in part by the NSF research grant #2137603, #2112606, #2117439, and #2320952. These authors contributed equally to this work. With the recent surge in language models and generative AI, a growing body of work [4]-[9] has begun leveraging AI techniques to capture semantic patterns in log sequences, aiming to enable more effective LogAD.
KLAAD: Refining Attention Mechanisms to Reduce Societal Bias in Generative Language Models
Kim, Seorin, Lee, Dongyoung, Lee, Jaejin
Large language models (LLMs) often exhibit societal biases in their outputs, prompting ethical concerns regarding fairness and harm. In this work, we propose KLAAD (KL-Attention Alignment Debiasing), an attention-based debiasing framework that implicitly aligns attention distributions between stereotypical and anti-stereotypical sentence pairs without directly modifying model weights. KLAAD introduces a composite training objective combining Cross-Entropy, KL divergence, and Triplet losses, guiding the model to consistently attend across biased and unbiased contexts while preserving fluency and coherence. Experimental evaluation of KLAAD demonstrates improved bias mitigation on both the BBQ and BOLD benchmarks, with minimal impact on language modeling quality. The results indicate that attention-level alignment offers a principled solution for mitigating bias in generative language models.
Optimizing Spreading Factor Selection for Mobile LoRa Gateways Using Single-Channel Hardware
The deployment of mobile LoRa gateways using low-cost single-channel hardware presents a significant challenge in maintaining reliable communication due to the lack of dynamic configuration support. In traditional LoRaWAN networks, Adaptive Data Rate (ADR) mechanisms optimize communication parameters in real time. However, such features are typically supported only by expensive multi-channel gateways. This study proposes a cost-effective and energy-efficient solution by statically selecting the optimal Spreading Factor (SF) using a two-phase algorithm. The method first applies rule-based exclusion to eliminate SFs that violate constraints related to distance, data rate, link margin, and regulatory limits. Remaining candidates are then evaluated using a weighted scoring model incorporating Time-on-Air, energy consumption, data rate, and link robustness. The proposed algorithm was validated through extensive field tests and NS-3 simulations under line-of-sight conditions. Results demonstrate that the selected SF matched the optimal SF in over 92% of cases across 672 simulated scenarios, confirming the algorithm's effectiveness. This approach offers a scalable alternative to dynamic protocols, enabling reliable mobile LoRa deployments in cost-sensitive environments such as agriculture and rural sensing applications.
VAE-GAN Based Price Manipulation in Coordinated Local Energy Markets
Mukherjee, Biswarup, Zhou, Li, Krishnan, S. Gokul, Kabirifar, Milad, Lakshminarayana, Subhash, Konstantinou, Charalambos
This paper introduces a model for coordinating prosumers with heterogeneous distributed energy resources (DERs), participating in the local energy market (LEM) that interacts with the market-clearing entity. The proposed LEM scheme utilizes a data-driven, model-free reinforcement learning approach based on the multi-agent deep deterministic policy gradient (MADDPG) framework, enabling prosumers to make real-time decisions on whether to buy, sell, or refrain from any action while facilitating efficient coordination for optimal energy trading in a dynamic market. In addition, we investigate a price manipulation strategy using a variational auto encoder-generative adversarial network (VAE-GAN) model, which allows utilities to adjust price signals in a way that induces financial losses for the prosumers. Our results show that under adversarial pricing, heterogeneous prosumer groups, particularly those lacking generation capabilities, incur financial losses. The same outcome holds across LEMs of different sizes. As the market size increases, trading stabilizes and fairness improves through emergent cooperation among agents.
Enhancing Materials Discovery with Valence Constrained Design in Generative Modeling
Cheng, Mouyang, Luo, Weiliang, Tang, Hao, Yu, Bowen, Cheng, Yongqiang, Xie, Weiwei, Li, Ju, Kulik, Heather J., Li, Mingda
Diffusion-based deep generative models have emerged as powerful tools for inverse materials design. Yet, many existing approaches overlook essential chemical constraints such as oxidation state balance, which can lead to chemically invalid structures. Here we introduce CrysVCD (Crystal generator with Valence-Constrained Design), a modular framework that integrates chemical rules directly into the generative process. CrysVCD first employs a transformer-based elemental language model to generate valence-balanced compositions, followed by a diffusion model to generate crystal structures. The valence constraint enables orders-of-magnitude more efficient chemical valence checking, compared to pure data-driven approaches with post-screening. When fine-tuned on stability metrics, CrysVCD achieves 85% thermodynamic stability and 68% phonon stability. Moreover, CrysVCD supports conditional generation of functional materials, enabling discovery of candidates such as high thermal conductivity semiconductors and high-$κ$ dielectric compounds. Designed as a general-purpose plugin, CrysVCD can be integrated into diverse generative pipeline to promote chemical validity, offering a reliable, scientifically grounded path for materials discovery.
A Machine Learning Framework for Predicting Microphysical Properties of Ice Crystals from Cloud Particle Imagery
Ko, Joseph, Harrington, Jerry, Sulia, Kara, Przybylo, Vanessa, van Lier-Walqui, Marcus, Lamb, Kara
The microphysical properties of ice crystals are important because they significantly alter the radiative properties and spatiotemporal distributions of clouds, which in turn strongly affect Earth's climate. However, it is challenging to measure key properties of ice crystals, such as mass or morphological features. Here, we present a framework for predicting three-dimensional (3D) microphysical properties of ice crystals from in situ two-dimensional (2D) imagery. First, we computationally generate synthetic ice crystals using 3D modeling software along with geometric parameters estimated from the 2021 Ice Cryo-Encapsulation Balloon (ICEBall) field campaign. Then, we use synthetic crystals to train machine learning (ML) models to predict effective density ($ρ_{e}$), effective surface area ($A_e$), and number of bullets ($N_b$) from synthetic rosette imagery. When tested on unseen synthetic images, we find that our ML models can predict microphysical properties with high accuracy. For $ρ_{e}$ and $A_e$, respectively, our best-performing single view models achieved $R^2$ values of 0.99 and 0.98. For $N_b$, our best single view model achieved a balanced accuracy and F1 score of 0.91. We also quantify the marginal prediction improvements from incorporating a second view. A stereo view ResNet-18 model reduced RMSE by 40% for both $ρ_e$ and $A_e$, relative to a single view ResNet-18 model. For $N_b$, we find that a stereo view ResNet-18 model improved the F1 score by 8%. This work provides a novel ML-driven framework for estimating ice microphysical properties from in situ imagery, which will allow for downstream constraints on microphysical parameterizations, such as the mass-size relationship.