arXiv subjects

Shuren Song

Publications and source records attributed to Shuren Song.

3 recordsLinked to original sources

arXiv2026

Written by AI, Managed by AI: Semantic Space Control and Index Sickness Elimination Across 391 Consecutive Sessions

The prevailing engineering intuition for addressing conceptual drift in long-horizon LLM collaboration is to trade more formal constraints for more reliable outputs -- designing symbolic identifier systems, accumulating defensive rules in System Prompts, expanding context windows. Our engineering record shows that in long-horizon settings, this direction may produce effects contrary to design intent. Using action research methods in a real software project (Bang-v3) spanning approximately one month and 391 collaborative sessions, we document and analyze the failure process of these strategies. When the symbolic system exceeds a complexity threshold, LLMs do not become more accurate -- instead, they abandon genuine understanding of business semantics, retreat to self-referential reasoning within the symbolic layer, and generate outputs that appear internally consistent but are physically disconnected from reality. We name this failure pattern "Index Sickness," and its canonical manifestation "Phantom Legislation." We name the underlying principle the "Pang Principle (Semantic Vitality Law)": natural language carrying explicit purpose conveys far greater information quality than symbolic expression. From this, we design and validate its physical engineering mechanism: "Baseline-Log Physical Separation." In the same project, this mechanism reduced AI Instructions volume by ~75%, and across the subsequent ~150 sessions, no recurrence of Index Sickness was observed. A bilingual companion version (Chinese) is included as supplementary material.

cs.SE↗

arXiv2022

Effect of viscosity on surface acoustic wave driven collective particle dynamics in sessile droplets: nebula, black holes and white dwarfs

Surface acoustic waves (SAW) can concentrate micro-particles in droplets within seconds. Yet, the mechanism is not clear and existing explanations fail by several orders of magnitude. In this paper, we analyze the effect of fluid viscosity and particle size on SAW-driven collective particle dynamics in droplets. In most of our experiments, the particles do not aggregate but instead remain away from the droplet center, thereby forming "black holes". We show that the black holes are due to steric hindrance wherein the poloidal streamlines that should drive particles to the center of the droplet come too close to the solid, so that the particles carried along these streamlines touch the solid wall on the edge of the black hole before reaching the center of the droplet. The size of these black holes is correlated with the size of the aggregates formed in less viscous droplets. This suggests a common formation mechanism for black holes and white dwarfs (aggregates). In the former, the particles touching the solid would be washed away by the fluid, whereas in the latter the particles would remain in contact with the solid and roll to the center of the droplet where an aggregate is formed. We also discuss the stability conditions of the aggregate at the bottom of the droplet. The concept of hydrodynamic shielding is then used to concentrate 1 $μ$m particles using 10 $μ$m beads as shields.

physics.flu-dyn↗

arXiv2021

Contactless generation and trapping of hydrodynamic knots in sessile droplets by acoustic screw dislocations

Hydrodynamics knots are not only promising elementary structures to study mass and momentum transfer in turbulent flows, but also potent analogs for other topological problems arising in particle physics. However, experimental studies of knots are highly challenging due to the limited control over knot generation and difficult observation of the resulting fast-paced multiscale flow evolution. In this paper, we propose using acoustic streaming to tie hydrodynamic knots in fluids. The method is contactless, almost instantaneous and is relatively insensitive to viscosity. Importantly, it allows starting from quite arbitrary three dimensional flow structures without relying on external boundary conditions. We demonstrate our approach by using an acoustic screw dislocation to tie a knot in a sessile droplet. We observe an inversion of the knot chirality (measured by the hydrodynamic helicity) as the topological charge of the screw dislocation is increased. Combined with recent progress in acoustic field synthesis, this work opens a window to study more complex hydrodynamic knot topologies at a broader range of space and timescales.

physics.flu-dyn↗