Tiered memory systems typically place pages based on access frequency (hotness), yet frequency alone fails to capture the true performance impact. We present PACT, an online, page-granular tiered memory design that elevates performance criticality to a first-class design principle. At its core is Per-page Access Criticality (PAC), a fine-grained metric that quantifies each page's contribution to application performance rather than merely counting accesses. PACT profiles PAC online using a lightweight analytical model that uniquely decomposes per-tier memory-level parallelism via hardware queue occupancy counters, enabling direct CPU stall attribution to individual pages. To handle highly skewed PAC distributions, PACT employs PAC-centric migration policies: eager demotion and adaptive promotion, to dynamically place performance-critical pages in DRAM. Across 13 workloads, PACT achieves up to 61% performance improvement over the best of 7 state-of-the-art tiering designs with up to 50× fewer migrations.

Heterogeneous memory combining DRAM and CXL exhibits variable performance, yet existing metrics correlate weakly with actual slowdown. We present CAMP, a principled framework for predicting CXL-induced slowdown. Our key insight is that a DRAM run (plus a CXL run for bandwidth-bound workloads) exposes the causal microarchitectural pressure points where CXL latency translates into additional processor stall cycles. CAMP captures these signals using 12 performance counters to analytically decompose slowdown into three orthogonal components: demand reads, cache/prefetching, and stores. CAMP also introduces a closed-form model for software-based weighted interleaving that predicts performance across DRAM--CXL ratios. Across 265 workloads on NUMA and three CXL devices, CAMP achieves 91--97% prediction accuracy within 10% absolute error. We demonstrate that these models enable practical system policies, including ''Best-shot'' interleaving and colocated workload placement, improving performance by up to 21% and 23% over existing tiering and colocation approaches.

In this article, a new security vulnerability in electricity market operations is identified. It involves certain parameters in the network model database whose errors, by nature, are difficult to detect and identify. These errors can either occur due to unintentional reasons or be maliciously introduced by cyber-adversaries. It is shown that by impacting the injection shift factors and transmission line congestion patterns, these errors may exert biases on locational marginal prices (LMPs), and thus impact the revenues received by the holders of financial transmission rights (FTRs). A method is then developed for identifying the network parameters whose errors are difficult to detect and may have severe impacts on the LMPs and FTR revenues. Simulation results in the IEEE 57-bus system are presented to illustrate and verify the analysis and the proposed method. The proposed framework can be used to conduct cyber-vulnerability assessment for power system model databases.

The microperturbation method (MPM) is an advanced online model identification technique for power systems, which utilizes some specifically designed multisine signal to perturb the system and to consequently stimulate amplitude-limited probing response that has desirable signal-to-noise ratio (SNR). The MPM removes the ambient noise from the contaminated probing response using statistical signal processing techniques and identifies system models by orthogonal decomposition-based subspace identification method (ORT). The capability to identify the precise system model at a low cost without impacting the system security gains the MPM tremendous application potentials. In this paper, we present an overview of the MPM, as well as its critical techniques and implementation procedures, and also shed lights on its potentials in real-time online applications in the power industry. The proposed approach is validated in an actual power system where the system dynamic model is successfully identified.