arXiv subjects

Zihao Bai

Publications and source records attributed to Zihao Bai.

5 recordsLinked to original sources

arXiv2026

Alignment Is Local: A Paired Diagnostic for GUI Agents under User-Side Persuasion

Trustworthy deployment of GUI agents in ubiquitous computing settings requires alignment that survives dynamic interaction and precise threat conditions, not just single-turn refusal of explicit harmful requests. We argue that prompt-level alignment, the dominant lightweight defense in current mobile agents, is a local phenomenon: it works reliably only in the narrow evaluation slice where it is typically measured, namely single-turn, explicitly-verbalized intent, and degrades systematically along two axes that any real user can traverse. Using a paired diagnostic on three frontier GUI agents, screen-grounded, user-side persuasion, with no environment injection, we show that a one-line guardrail achieves large single-shot ASR reductions, up to roughly 40 points, at near-zero over-refusal cost. Nevertheless, moving from independent probes to four-turn escalation chains raises guarded ASR by approximately 20 points on every model. Relative to the neutral baselines, this increase reflects substantial guardrail erosion for Qwen but a largely defense-orthogonal dynamic risk for Claude and GPT. The sign of the salience gap flips under the guardrail: concealed requests are not systematically more successful than explicit ones without a guardrail, but are more successful with one, indicating that the defense engages primarily when intent is named. Static single-turn ASR therefore overstates deployed robustness by a systematic and predictable margin.

cs.CR↗

arXiv2026

SurgRFO: Foundation Model Based Compositional Synthesis of Critical Retained Foreign Objects in Intraoperative Chest X-rays

Critical retained foreign objects (RFOs) on intraoperative chest radiographs are rare but high-risk events. Their scarcity limits robust automated detection model training and generalization. We introduce SurgRFO, a two-stage synthesis framework for generating realistic RFO-present intraoperative chest X-rays. In Stage 1, a Roentgen chest X-ray foundation model is fine-tuned on surgical-domain images to generate realistic RFO-free backgrounds that preserve anatomy, indwelling lines and tubes, and intraoperative imaging characteristics. In Stage 2, a lightweight generator trained on localized RFO patches from limited positive cases synthesizes diverse RFO instances, which are composited onto generated backgrounds using conditional Poisson fusion to improve photometric consistency. We evaluate SurgRFO through (i) a blinded clinician study assessing realism and clinical plausibility, and (ii) downstream detection experiments in which synthesized data are used to augment Faster R-CNN, YOLOv8, and RetinaNet. SurgRFO consistently improves sensitivity at low false-positive-per-image (FPPI) operating points on internal and external test sets. Clinician ratings indicate that the synthesized images achieve realism comparable to real intraoperative images. Ablation analyses further examine fusion strategies and synthesis scale. Ethical safeguards for synthetic surgical data are also discussed.

eess.IV↗

arXiv2023

Nucleation of Supercooled Liquid Aluminum: an First-Principles Molecular Dynamics Study Based on Orbital-Free Density Functional Theory

Nucleation is very common physical phenomena that occur at the microscopic scale. However, due to the presence of nucleation barriers, the time scale of nucleation is usually much longer than that of microscopic particle dynamics. These characteristics make it significantly challenging to study nucleation experimentally, theoretically, or computationally. In this work, the authors explore the significance and feasibility of applying first-principles calculations based on orbital-free density functional theory (OFDFT) to simulate nucleation in supercooled liquids. To analyze the performance of OFDFT in simulating nucleation in supercooled liquids, the authors employ orbital-free density functional theory molecular dynamics (OFDFT-MD) to compute the melting point of aluminum and simulate nucleation in supercooled liquid aluminum. By utilizing GlassViewer, an order parameter calculation software for nucleation problems developed by the authors, the evolution of the bond-orientational order (BOO) parameters and the mean first-passage time (MFPT) are calculated to analyze the changes of local atomic structures during the nucleation processes and the nucleation kinetics parameters of precursors. The results are then compared with those obtained using the embedded atom method (EAM) semi-empirical potential. The results indicate that OFDFT can provide relatively reliable melting points, and the predicted nucleation parameters are consistent with the results obtained using the EAM potential. This work demonstrates the feasibility of employing OFDFT for simulating nucleation in supercooled liquids, enabling the exploration of the effects of electronic structures and electromagnetic fields on nucleation processes in supercooled liquids using this first-principles approach.

physics.chem-ph↗

arXiv2022

Experiment Research on the Sequence and Mechanism of Gold and Silver Composite Nanocrystal Synthesis

In this experiment, the authors reviewed the principles and methods for the synthesis and characterization of gold-silver nanocrystals and proposed two possible synthesis mechanisms for Gold and Silver Composite Nanocrystals. Gold nanocrystals, silver nanocrystals, and Gold and Silver Composite Nanocrystals were prepared by the "Sodium citrate seedless method"(Turkevich Method). The products were characterized by dynamic light scattering (DLS), ultraviolet-visible light spectroscopy (UV), and scanning electron microscopy (SEM). Through comparative experiments, synthesis mechanisms behind different synthesis sequences of gold-silver nanocrystals are analyzed. Observed exotic phenomena are discussed.

physics.chem-ph↗

arXiv2022

Research and experimental design of Astrojax double balls trajectory based on double pendulum system

Based on the double pendulum and Lagrange equation, the moving particles are captured by a binocular three-dimensional capture camera. Two trajectory models of Astrojax and the relationship between trajectory empirical formula and parameters are established. Through research, the calculated trajectory of this formula and related parameters fit well with the actual measured trajectory, and can accurately predict and change the trajectory of the model. The equipment and materials required in the experiment are simple and easy to obtain, and the experimental theme is relatively interesting and novel, which can be applied as an extended experiment in college physics experiment course, so that students can understand the motion characteristics of the double pendulum and learn physics from life. The designing experiment can not only improve students' interest in learning, but also broaden their knowledge and cultivate their practical ability.

physics.ed-ph↗