arXiv subjects

Qingsheng Yang

Publications and source records attributed to Qingsheng Yang.

3 recordsLinked to original sources

arXiv2026

Eversion Buckling of Toroidal Shells: Mechanism, Bifurcation, and Applications in Energy Absorption

Thin shells can store and release elastic energy through large geometric transformations, but their post-deformation stability is often highly sensitive to geometry and loading direction. Here, we study the eversion of open toroidal shells generated by revolving a meridional arc about an external axis and identify a geometry-controlled instability, which we define as eversion buckling. After eversion, the shell may either remain in an axisymmetric everted state or spontaneously collapse into a non-axisymmetric configuration. We show that this transition is governed by the competition between bending and membrane energies. A scaling analysis leads to a dimensionless geometric parameter that predicts the onset of eversion buckling, namely, the spontaneous loss of stability of the axisymmetric everted configuration after unloading. Finite element simulations and experiments confirm that this parameter collapses the stability data for shells with different geometries, including circular and semi-elliptical generating curves. The loss of axisymmetric stability is consistent with a pitchfork-like symmetry-breaking transition, in which the collapsed state has no preferred in-plane direction because of the axisymmetry of the everted shell. When the axisymmetric everted configuration is stable, a finite perturbation can trigger rapid snap-through toward a lower-energy collapsed equilibrium, accompanied by substantial volume contraction and a triggering response that is relatively insensitive to boundary constraints. We further show that assemblies of these shells behave as granular energy-absorbing systems, exhibiting a stable stress plateau, delayed densification, and substantial frictional dissipation during collective rearrangement. These results provide a mechanics-based route for designing shell assemblies with robust, direction-insensitive energy absorption.

math-ph↗

arXiv2023

A photo-mechanical coupling theory for photoisomerization hydrogel considering the distribution state of molecular chains

Owing to the possibility of controlling its specific mechanical behaviors up taken by irradiated by light at particular wavelengths, the photoisomerization hydrogels have a broad range of potential applications. A theory connecting the optical excitation to mechanical behavior is essential to precisely control the photo-mechanical behaviors of the hydrogel. In this work, a photo-mechanical coupling theory is developed to describe the photo-mechanical responses of photoisomerization hydrogels within the framework of finite deformation continuum thermodynamics. In the model, the deformation gradient is decomposed into two parts to effectively model the light induced deformation and the elastic one. To consider the effect of the optical excitation on mechanical behaviors, we first investigate the transporting mechanism of light in hydrogel, as well as the photochemical reaction process; and we then explore the disturbance of light irradiation on the equilibrium of the thermodynamic system of hydrogel, as well as the relationship of conformational entropy of hydrogel network with the photochemical reaction; finally, based on the entropy elasticity theory, we propose a new free energy function of the photosensitive hydrogel to consider the effect of molecular chain distribution evolution on the stiffness of the hydrogel network. With the implementation of the proposed model, we study the photo-mechanical behaviors and mechanical properties of photoisomerization hydrogels. The present research is helpful for understanding the multi-field coupling behaviors of the photosensitive hydrogel, and then providing guidelines for the application of photoisomerization hydrogel.

physics.chem-ph↗

arXiv2023

Video traffic identification with novel feature extraction and selection method

In recent years, the rapid rise of video applications has led to an explosion of Internet video traffic, thereby posing severe challenges to network management. Therefore, effectively identifying and managing video traffic has become an urgent problem to be solved. However, the existing video traffic feature extraction methods mainly target at the traditional packet and flow level features, and the video traffic identification accuracy is low. Additionally, the issue of high data dimension often exists in video traffic identification, requiring an effective approach to select the most relevant features to complete the identification task. Although numerous studies have used feature selection to achieve improved identification performance, no feature selection research has focused on measuring feature distributions that do not overlap or have a small overlap. First, this study proposes to extract video-related features to construct a large-scale feature set to identify video traffic. Second, to reduce the cost of video traffic identification and select an effective feature subset, the current research proposes an adaptive distribution distance-based feature selection (ADDFS) method, which uses Wasserstein distance to measure the distance between feature distributions. To test the effectiveness of the proposal, we collected a set of video traffic from different platforms in a campus network environment and conducted a set of experiments using these data sets. Experimental results suggest that the proposed method can achieve high identification performance for video scene traffic and cloud game video traffic identification. Lastly, a comparison of ADDFS with other feature selection methods shows that ADDFS is a practical feature selection technique not only for video traffic identification, but also for general classification tasks.

cs.NI↗