Nonlinear Isometries on Schatten- p

Let H be a complex Hilbert space; denote by Alg  and p(H) the atomic nest algebra associated with the atomic nest on H and the space of Schatten-p class operators on, H respectively. Let p(H)∩Alg  be the space of Schatten-p class operators in Alg . When 1≤p<+∞ and p≠2, we give a complete characterization of nonlinear surjective isometries on p(H)∩Alg . If p=2, we also prove that a nonlinear surjective isometry on 2(H)∩Alg  is the translation of an orthogonality preserving map

Star network non-n-local correlations can resist consistency noises better

Imperfections from devices can result in the decay or even vanish of non-n-local correlations as the number of parties n increases in the polygon and linear quantum networks ([Phys. Rev. A 106, 042206 (2022)] and [Phys. Rev. A 107, 032404 (2023)]). Even so this phenomenon is also for the special kind of noises, including consistency noises of a sequence of devices, which means the sequence of devices have the same probability fails to detect. However, in the paper, we discover that star network quantum non-n-local correlations can resist better consistency noises than these in polygon and linear networks. We first calculate the noisy expected value o f star network non-n-locality and analyze the persistency conditions theoretically. When assume that congener devices have the consistency noise, the persistency number of sources n has been rid of such noises, and approximates to the infinity. Polygon and linear network non-n-local correlations can not meet the requirements. Furthermore, we explore the change pattern of the maximal number of sources nmax such that non-nmax-local correlation can be demonstrated in the star network under the influence of partially consistent noises, which is more general than consistent ones.Comment: 23pages, 16 figure

Interlaminar stresses and fracture behavior in thickness-tapered composite laminates

Design and manufacture of a variable thickness composite laminate such as a helicopter yoke involves tapering the laminate by dropping individual plies at discrete internal locations, in order to tailor the stiffness of the laminate. The ply drop in the laminate creates large interlaminar stresses and initiates delamination. Therefore, there is a necessity to investigate the fundamental failure mechanisms and controlling parameters that account for the delamination mode of failure in tapered laminates. In this thesis, a numerical and experimental study on interlaminar stresses and delamination in tapered laminates is presented, including a critical and comprehensive review on earlier works on this type of structure. Numerical analyses performed involved development of partial hybrid stress finite elements needed to enhance computational efficiency, and development of a physical concept-based modified shear-lag model that is based on the essential assumptions that both plies and resin layers are treated as carriers of tensile stress and also to act as stress-transfer media. Experimental analysis was attempted to assess the accuracy of the numerical predictions. For this purpose, tapered NCT-301 Graphite/Epoxy specimens were manufactured using a ply in-fill technique for the cured consolidation and tested under quasi-static uniaxial tension. To perform strength and delamination analyses of the tapered laminate, the laminate was modeled as a generalized plane deformation problem, where all the variables involved in the model are independent of the coordinate system. Also quasi-three dimensional partial hybrid finite elements were used to quantify the analysis. In addition to the plies, the inter-ply resin at the critical ply interface was also modeled in order to have direct and realistic interlaminar responses. Stress-based criteria that have proved to be effective in determination of critical location and load of delamination onset were utilized in this study to predict the delamination strength of the laminate. A good correlation between the predictions and experimental results were observed. Evaluation of strain energy release rates of delaminations occurring at the critical interfaces of the tapered laminate was carried out by using the J -integral approach. This was possible because of the path-independence of the J -integral that results in avoiding the need for analyzing the singular stress field near the delamination tip and reducing the computing effort required. Effects of various design parameters on the structural performance of the tapered laminate were studied so as to gain an insight into design considerations for tapered composite structures

Contrastive Bayesian Analysis for Deep Metric Learning

Recent methods for deep metric learning have been focusing on designing different contrastive loss functions between positive and negative pairs of samples so that the learned feature embedding is able to pull positive samples of the same class closer and push negative samples from different classes away from each other. In this work, we recognize that there is a significant semantic gap between features at the intermediate feature layer and class labels at the final output layer. To bridge this gap, we develop a contrastive Bayesian analysis to characterize and model the posterior probabilities of image labels conditioned by their features similarity in a contrastive learning setting. This contrastive Bayesian analysis leads to a new loss function for deep metric learning. To improve the generalization capability of the proposed method onto new classes, we further extend the contrastive Bayesian loss with a metric variance constraint. Our experimental results and ablation studies demonstrate that the proposed contrastive Bayesian metric learning method significantly improves the performance of deep metric learning in both supervised and pseudo-supervised scenarios, outperforming existing methods by a large margin.Comment: Accepted by IEEE Transactions on Pattern Analysis and Machine Intelligenc