arXiv subjects

Peiyuan Sun

Publications and source records attributed to Peiyuan Sun.

7 recordsLinked to original sources

arXiv2026

Dasgupta's Hierarchical Clustering Objective: Geometry and the Price of the Cardinality Constraint

The cost of a hierarchical clustering can be represented by an ultrametric whose lowest-common-ancestor labels are cluster cardinalities. We relate this known representation to the shortest-path geometry of a similarity graph. For a connected support graph $G$, let $d_G$ be its unit-length shortest-path metric and let the edge weights enter only the objective. We prove that the shifted Dasgupta optimum is exactly the minimum edge-weighted cost of a cardinality-realizable ultrametric that dominates $d_G$. Connectedification lemmas put this problem and its freely labeled dominating-ultrametric relaxation on the same class of connected binary hierarchies, labeled respectively by cardinality and graph diameter. As a sharp baseline, we determine the exact worst-case price of cardinality realizability: on every $n$-vertex instance the ratio of the two optima is at most $(2n-1)/3$, with equality on the unweighted complete graph; the sharp factor for the standard unshifted objective is $2(n+1)/3$. Our principal structural result bounds this gap by a hereditary weighted fragmentation profile defined through connected balanced cuts. Uniform local control gives an $O(\log n)$ gap, polynomial decay gives a constant gap, and the logarithmic order is tight even for unweighted trees of maximum degree $3$. On locally regular bounded-degree trees, the hierarchy can be constructed in $O(n\log n)$ time. An energy decomposition and a geometric density bound provide supporting instance-sensitive estimates. Thus the cardinality label has an unavoidable linear worst case but admits substantially smaller bounds on natural sparse graph classes.

cs.DS↗

arXiv2025

Declarative Data Pipeline for Large Scale ML Services

Modern distributed data processing systems struggle to balance performance, maintainability, and developer productivity when integrating machine learning at scale. These challenges intensify in large collaborative environments due to high communication overhead and coordination complexity. We present a "Declarative Data Pipeline" (DDP) architecture that addresses these challenges while processing billions of records efficiently. Our modular framework seamlessly integrates machine learning within Apache Spark using logical computation units called Pipes, departing from traditional microservice approaches. By establishing clear component boundaries and standardized interfaces, we achieve modularity and optimization without sacrificing maintainability. Enterprise case studies demonstrate substantial improvements: 50% better development efficiency, collaboration efforts compressed from weeks to days, 500x scalability improvement, and 10x throughput gains.

cs.DC↗

arXiv2025

Deep-Reinforcement-Learning-Based Adaptive State-Feedback Control for Inter-Area Oscillation Damping with Continuous Eigenvalue Configurations

Controlling inter-area oscillation (IAO) across wide areas is crucial for the stability of modern power systems. Recent advances in deep learning, combined with the extensive deployment of phasor measurement units (PMUs) and generator sensors, have catalyzed the development of data-driven IAO damping controllers. In this paper, a novel IAO damping control framework is presented by modeling the control problem as a Markov Decision Process (MDP) and solving it through deep reinforcement learning (DRL). The DRL-based controller is trained in the state space with continuous eigenvalue configurations. To optimize control performance and cost-efficiency, only a subset of generators, identified by global participation factors, are selected for control. In addition, a switching control strategy (SCS) is introduced that effectively integrates the DRL-based controller with power system stabilizers (PSSs) to enhance overall performance. The simulation results on the IEEE 39-bus New England power system show that the proposed method outperforms two benchmark methods regarding the transient response. The DRL-based controller trained on the linear state-space environment can be directly tested in the nonlinear differential-algebraic environment. The robustness of the proposed method against communication delays has been thoroughly investigated.

eess.SY↗

arXiv2023

Transferable Deep Learning Power System Short-Term Voltage Stability Assessment with Physics-Informed Topological Feature Engineering

Deep learning (DL) algorithms have been widely applied to short-term voltage stability (STVS) assessment in power systems. However, transferring the knowledge learned in one power grid to other power grids with topology changes is still a challenging task. This paper proposed a transferable DL-based model for STVS assessment by constructing the topology-aware voltage dynamic features from raw PMU data. Since the reactive power flow and grid topology are essential to voltage stability, the topology-aware and physics-informed voltage dynamic features are utilized to effectively represent the topological and temporal patterns from post-disturbance system dynamic trajectories. The proposed DL-based STVS assessment model is tested under random operating conditions on the New England 39-bus system. It has 99.99\% classification accuracy of the short-term voltage stability status using the topology-aware and physics-informed voltage dynamic features. In addition to high accuracy, the experiments show good adaptability to PMU errors. Moreover, The proposed STVS assessment method has outstanding performance on new grid topologies after fine-tuning. In particular, the highest accuracy reaches 99.68\% in evaluation, which demonstrates a good knowledge transfer ability of the proposed model for power grid topology change.

eess.SY↗

arXiv2022

Fast Transient Stability Prediction Using Grid-informed Temporal and Topological Embedding Deep Neural Network

Transient stability prediction is critically essential to the fast online assessment and maintaining the stable operation in power systems. The wide deployment of phasor measurement units (PMUs) promotes the development of data-driven approaches for transient stability assessment. This paper proposes the temporal and topological embedding deep neural network (TTEDNN) model to forecast transient stability with the early transient dynamics. The TTEDNN model can accurately and efficiently predict the transient stability by extracting the temporal and topological features from the time-series data of the early transient dynamics. The grid-informed adjacency matrix is used to incorporate the power grid structural and electrical parameter information. The transient dynamics simulation environments under the single-node and multiple-node perturbations are used to test the performance of the TTEDNN model for the IEEE 39-bus and IEEE 118-bus power systems. The results show that the TTEDNN model has the best and most robust prediction performance. Furthermore, the TTEDNN model also demonstrates the transfer capability to predict the transient stability in the more complicated transient dynamics simulation environments.

eess.SY↗

arXiv2021

Hyperbolic Multiplex Network Embedding with Maps of Random Walk

Recent research on network embedding in hyperbolic space have proven successful in several applications. However, nodes in real world networks tend to interact through several distinct channels. Simple aggregation or ignorance of this multiplexity will lead to misleading results. On the other hand, there exists redundant information between different interaction patterns between nodes. Recent research reveals the analogy between the community structure and the hyperbolic coordinate. To learn each node's effective embedding representation while reducing the redundancy of multiplex network, we then propose a unified framework combing multiplex network hyperbolic embedding and multiplex community detection. The intuitive rationale is that high order node embedding approach is expected to alleviate the observed network's sparse and noisy structure which will benefit the community detection task. On the contrary, the improved community structure will also guide the node embedding task. To incorporate the common features between channels while preserving unique features, a random walk approach which traversing in latent multiplex hyperbolic space is proposed to detect the community across channels and bridge the connection between node embedding and community detection. The proposed framework is evaluated on several network tasks using different real world dataset. The results demonstrates that our framework is effective and efficiency compared with state-of-the-art approaches.

cs.SI↗

arXiv2018

Arena Model: Inference About Competitions

The authors propose a parametric model called the arena model for prediction in paired competitions, i.e. paired comparisons with eliminations and bifurcations. The arena model has a number of appealing advantages. First, it predicts the results of competitions without rating many individuals. Second, it takes full advantage of the structure of competitions. Third, the model provides an easy method to quantify the uncertainty in competitions. Fourth, some of our methods can be directly generalized for comparisons among three or more individuals. Furthermore, the authors identify an invariant Bayes estimator with regard to the prior distribution and prove the consistency of the estimations of uncertainty. Currently, the arena model is not effective in tracking the change of strengths of individuals, but its basic framework provides a solid foundation for future study of such cases.

cs.LG↗