Electronics

Satellite-enabled content delivery networks (S-CDNs) are needed to improve content access for wide-area, remote, and highly dynamic users, for whom relying only on terrestrial CDN infrastructure is often insufficient. However, in conventional CDN systems, request acceptance and origin fetching are not tightly coupled. In satellite–ground environments with high latency, dynamic connectivity, and limited observability of requester state, low-cost and fully protocol-compliant requests may still trigger disproportionate backend work. This paper attributes the problem to open-loop request admission and studies two protocol-compliant paths. The range path is an instance of a known CDN cost asymmetry. The second path, called “Disconnection-induced amplification after request submission,” builds on known connection-decoupling behavior. Its attack realization is a protocol-compliant requester-side stop inspired by satellite coverage motion. The stop emulates the observable effect of a user leaving the service area after task triggering. The experiment evaluates this emulation. Experiments on an in-orbit prototype and a matched terrestrial configuration, together with supplementary analysis, show substantial back-to-origin amplification along both paths: the smallest byte-range request on uncached objects reaches a peak amplification of about 15,000, while the disconnection-induced path causes persistent satellite-side bandwidth occupation, a lower benign completion ratio, and higher downlink overhead. These findings indicate that cache misses in S-CDNs are not only performance events but also security-relevant points of backend commitment.

Conventional unscented Kalman filter (UKF)-based inertia estimators are constrained by slow convergence within the limited inertial response window and a fixed measurement noise variance that cannot capture time-varying uncertainty during disturbances. This paper proposes ARX-IG-UKF, an online nodal inertia estimation method combining autoregressive modeling with exogenous inputs (ARX) for initialization and inverse-gamma (IG) noise adaptation. First, an ARX model fitted to early post-disturbance power frequency data provides an initial nodal inertia estimate. This estimate initializes a state-space model describing the inertial responses of synchronous generators and renewable generation units, reducing the convergence time required for short-window estimation. An IG distribution is then used to update the measurement noise covariance online in response to deviations associated with primary frequency regulation. The adaptive covariance is incorporated into the UKF to reduce the influence of non-inertial dynamics and recursively estimate nodal inertia. Simulation studies demonstrate consistent convergence and stable estimates under a range of operating conditions, supporting the applicability of the method to online nodal inertia identification in complex operating scenarios.

Embedded Flash chip probing (CP) testing in an automotive Microcontroller Unit (MCU) involves long test flows and numerous test items. Conventional BIST-based testing relies on step-by-step Automated Test Equipment (ATE) instruction configuration, status polling, and result readout, causing considerable ATE interaction overhead that grows with the number of test items. This paper proposes an Auto-CP Built-In Self-Test (BIST) method with entropy-guided two-stage instruction set compression and on-chip autonomous scheduling for embedded Flash CP testing. Unlike conventional lossless compression that operates directly on raw instructions, the proposed method uses information entropy to quantify instruction redundancy and decomposes the original instruction stream into reusable instruction templates and a sequence scheduling stream. Structural compression removes repeated long instruction fields, while Huffman lossless coding shortens high-frequency symbols. On-chip decoding and scheduling logic then enable the ATE to load the compressed test program once and read the final results, eliminating step-by-step control of each test item. For a 40 nm 1 MB embedded Flash CP test at 15 MHz using an Advantest 93000 ATE, Auto-CP reduces the measured total CP test time from 42.65 s to 36.25 s, i.e., by 15%. The average ATE overhead ratio is lowered from 26% to 13%. The results show that the proposed method effectively reduces the ATE interaction overhead and improves the embedded Flash mass production CP test efficiency.