arXiv subjects

Peicheng Xu

Publications and source records attributed to Peicheng Xu.

5 recordsLinked to original sources

arXiv2026

Adversarial LassoNet: Robust Feature Selection via Stability-Driven Sparse Learning

Sparse feature selection is critical for high-dimensional machine learning, yet traditional $\ell_1$-regularized methods are often brittle under observational noise and spurious correlations, leading to unstable feature supports and degraded generalization. Although adversarial training has been widely used to improve model robustness, its interaction with hierarchical sparse feature selection remains underexplored. In this work, we propose Adversarial LassoNet (AdLNet), a stability-driven sparse feature selection framework that integrates input-space adversarial perturbations with the hierarchical sparsity mechanism of LassoNet. We derive a tractable first-order adversarial approximation under local smoothness assumptions and provide an NTK-inspired spectral analysis to characterize how perturbation-driven training can reduce gradient concentration. Experiments on high-dimensional SERS data, six public benchmark datasets, and ColoredMNIST show that AdLNet maintains competitive sparse-selection performance while improving out-of-distribution robustness by 4.4\% and feature support reproducibility by 6.3\% under nearly matched support sparsity on ColoredMNIST. On the high-dimensional lung cancer screening dataset, AdLNet achieves a 5.3\% test accuracy gain and a 6.0\% AUC improvement over vanilla LassoNet. Code and dataset are available at https://github.com/719573/Adversarial-LassoNet.

cs.LG↗

arXiv2018

Tunable colloidal photonic crystals

Spherical colloids arranged in a crystalline order are known to produce structural colors. The intensity and brilliance of such photonic crystals require high size-monodispersity of the colloids, a low number of lattice defects and disorder, as well as a relatively large refractive index contrast between the scattering colloids and the continuous background. Here we present the unexpected photonic properties of aqueous suspensions of charge-stabilized, 186 nm large, fluorinated colloids with a refractive index of 1.37. Employing reflectivity, optical observation, small angle x-ray scattering measurements and reflectivity modeling, we demonstrate that these suspensions become partially transparent while showing strong, almost angle-independent color in reflection despite the very small refractive index difference. Under certain conditions, additional sharp Bragg reflections are observed. We were able to tune the observed structural colors continuously across the entire visible range by simply changing the volume fraction of these colloidal suspensions, which show a white appearance when dilute, structural color and Bragg peaks when concentrated enough to form Wiegner crystal, and angle-independent color when very concentrated and in a glassy phase.

physics.optics↗

arXiv2018

A Facile Approach to Prepare Self-Assembled, Nacre-Inspired Clay/Polymer Nano-Composites

Nature provides many paradigms for the design and fabrication of artificial composite materials. Inspired by the relationship between the well-ordered architecture and biopolymers found in natural nacre, we present a facile strategy to construct large-scale organic/inorganic nacre-mimetics with hierarchical structure via a water-evaporation self-assembly process. Through hydrogen bonding, we connect Laponite-nanoclay platelets with each other using naturally abundant cellulose creating thin, flexible films with a local brick-and-mortar architecture. While the aqueous solution displays liquid crystalline textures, the dried films show a pronounced Young's modulus (9.09 GPa) with a maximum strength of 298.02 MPa and toughness of 16.63 MJm-3. In terms of functionalities, we report excellent glass-like transparency along with exceptional shape-persistent flame shielding. We also demonstrate that through metal ion-coordination we can further strengthen the interactions between the polymers and the nanoclays. These ion-treated hybrid films exhibit further enhanced mechanical, and thermal properties as well as resistance against swelling and dissolution in aqueous environments. We believe that our simple pathway to fabricate such versatile polymer/clay nanocomposites can open avenues for inexpensive production of environmentally friendly, biomimetic materials in aerospace, wearable electrical devices, artificial muscle, and food packaging industry.

cond-mat.soft↗

arXiv2018

Inducing transparency in the films of highly scattering particles

Today colloids are employed in various products from creams and coatings to electronics. The ability to control their chemical, optical, or electronic features by controlling their size and shape explains why these materials are so widely employed. Nevertheless, altering some of these properties may also lead to some undesired side effects, one of which is an increase in optical scattering upon concentration. Here, we address this strong scattering issue in films made of colloids with high surface roughness. We focus on raspberry type polymeric particles made of a spherical polystyrene core decorated by small hemispherical domains of acrylate. Owing to their surface charge and model roughness, aqueous dispersions of these particles display an unusual stability against aggregation. Under certain angles, their solid films display a brilliant red color due to Bragg scattering but otherwise appear completely white on account of`strong scattering. To suppress the scattering and induce transparency, we prepared films by hybridizing them either with oppositely-charged PS-particles that fit the length-scale of the raspberry roughness or with quantum dots. We report that the smaller PS-particles prevent raspberry particle aggregation in solid films and suppress scattering by decreasing the spatial variation of the refractive index. We believe that the results presented here provide a simple strategy to suppress strong scattering of rough particles and allow for their utilization in optical coatings, cosmetics, or photonics.

physics.app-ph↗

arXiv2017

Liquid crystalline behaviour of self-assembled Laponite PLL-PEG nanocomposites

Synthetic Laponite-clay particles with platelet-like shape display strong aging when dispersed in aqueous solutions, preventing latter from reaching their natural liquid-crystalline equilibrium state. Here we introduce a facile method that successfully prevents this aging behaviour and enables accessing the systems' liquid-crystal and crystalline phases. We graft the comb-like polymer, poly(L-lysine)-g-poly(ethylene glycol) (PLL-PEG), onto the clay surfaces from solution, thereby screening the negative surface charges and thus ensuring steric stabilisation. We show zeta-sizer and rheology measurements, respectively, confirming complete steric coating and that aging of dilute samples is completely suppressed even after a year. Using evaporation as means to concentrate the particles, we observe various liquid crystalline textures under a polarized optical microscope (POM). Upon sequential spreading and drying, we are also able to obtain transparent films with hierarchical architecture.

cond-mat.soft↗