How is Gaze Influenced by Image Transformations? Dataset and Model

Data size is the bottleneck for developing deep saliency models, because collecting eye-movement data is very time consuming and expensive. Most of current studies on human attention and saliency modeling have used high quality stereotype stimuli. In real world, however, captured images undergo various types of transformations. Can we use these transformations to augment existing saliency datasets? Here, we first create a novel saliency dataset including fixations of 10 observers over 1900 images degraded by 19 types of transformations. Second, by analyzing eye movements, we find that observers look at different locations over transformed versus original images. Third, we utilize the new data over transformed images, called data augmentation transformation (DAT), to train deep saliency models. We find that label preserving DATs with negligible impact on human gaze boost saliency prediction, whereas some other DATs that severely impact human gaze degrade the performance. These label preserving valid augmentation transformations provide a solution to enlarge existing saliency datasets. Finally, we introduce a novel saliency model based on generative adversarial network (dubbed GazeGAN). A modified UNet is proposed as the generator of the GazeGAN, which combines classic skip connections with a novel center-surround connection (CSC), in order to leverage multi level features. We also propose a histogram loss based on Alternative Chi Square Distance (ACS HistLoss) to refine the saliency map in terms of luminance distribution. Extensive experiments and comparisons over 3 datasets indicate that GazeGAN achieves the best performance in terms of popular saliency evaluation metrics, and is more robust to various perturbations. Our code and data are available at: https://github.com/CZHQuality/Sal-CFS-GAN

Structural failure of layered thermoelectric In₄Se_(3-δ) semiconductors is dominated by shear slippage

In₄Se_(3-δ) semiconductors exhibit high zT as an n-type TE material, making them promising materials for thermoelectric (TE) applications. However, their commercial applications have been limited by the degradation of their mechanical properties upon cyclic thermal loading, making it important to understand their stress response under external loadings. Thus we applied molecular dynamics (MD) simulations using a density functional theory (DFT) derived force field to investigate the stress response and failure mechanism of In₄Se_(3-δ) under shear loading as a function of strain rates and temperatures. We considered the most plausible slip system (001)/ based on the calculations. We find that shear slippage among In/Se layered structures dominates the shear failure of In₄Se_(3-δ). Particularly, Se vacancies promote disorder of the In atoms in the shear band, which accelerates the shear failure. With increasing temperature, the critical failure strength of In4Se3 and the fracture strain of In₄Se₃ decrease gradually. In contrast, the fracture strain of In₄Se_(2.75) is improved although the ultimate strength decreases as temperature increases, suggesting that the Se vacancies enhance the ductility at high temperature. In addition, the ultimate strength and the fracture strain for In₄Se_(2.75) increase slightly with the strain rate. This strain rate effect is more significant at low temperature for In₄Se_(2.75) because of the Se vacancies. These findings provide new perspectives of intrinsic failure of In₄Se_(3-δ) and theory basis for developing robust In₄Se_(3-δ) TE devices

Synergetic Evolution of Sacrificial Bonds and Strain-Induced Defects Facilitating Large Deformation of Bi₂Te₃ Semiconductor

Bismuth telluride (Bi₂Te₃)-based semiconductors are one of the typical inorganic thermoelectric (TE) materials with excellent energy conversion efficiency, but the intrinsic brittleness severely limits their mechanical performance for further application with long-term reliability and in wearable devices. To understand the recent mechanical improvement of ductile and flexible inorganic TE materials at the atomic scale, here, we use molecular dynamics simulations to intuitively illuminate the enhanced shear deformability and performance stability of the brittle Bi2Te3 crystal through the tailored effects of surfaces. We reveal that the peculiar microbehavior originates from the layered hierarchical bonding structure with weak but reversible van der Waals force, namely, a sacrificial bond (SB), between Te1–Te1 adjacent layers. The synergetic evolution of local structures including SBs and strain-induced defects tends to partly compensate for the mechanical degradation caused by structure softening during shearing, achieving a relatively large strain before cleavage. The inspired engineering strategy of synergistically optimizing bonds and defects opens a pathway for designing multiscale hierarchical inorganic TE materials with excellent overall performance

Self-Efficacy and Depression in Boxers: A Mediation Model

Background: Depression has become one of the most common problems faced by athletes. In many mental health problems, its production and development mechanisms and influencing factors have received full attention from researchers, whereas boxers’ depression has received limited attention. This study explored the relationship between boxers’ self-efficacy and depression, as well as the effect of self-control as a mediating factor. Methods: This study used the athlete self-efficacy scale (ASES), the self-control scale (SCS), and the Center for Epidemiologic Studies depression scale (CES-D). Using a large number of randomly selected samples, a total of N=231 boxers (age: M =20.28, SD = 2.60, ages around 18 to 32; the total number of years of exercise: M = 6.07 years, SD = 2.90, years around 1 to 15; 144 male) of Chinese national athletes participated the study. Results: Self-efficacy and self-control were negatively correlated with depression; self-efficacy was positively correlated with self-control. In addition, self-control played a partial mediation role between self-efficacy and depression among boxers. Conclusion: Above all, an important way to improve and prevent the depression of Chinese boxers maybe enhance their level of self-efficacy and self-control

Structure and Failure Mechanism of the Thermoelectric CoSb_3/TiCoSb Interface

The brittle behavior and low strength of CoSb_3/TiCoSb interface are serious issues concerning the engineering applications of CoSb_3 based or CoSb_3/TiCoSb segmented thermoelectric devices. To illustrate the failure mechanism of the CoSb_3/TiCoSb interface, we apply density functional theory to investigate the interfacial behavior and examine the response during tensile deformations. We find that both CoSb_3(100)/TiCoSb(111) and CoSb_3(100)/TiCoSb(110) are energetically favorable interfacial structures. Failure of the CoSb_3/TiCoSb interface occurs in CoSb_3 since the structural stiffness of CoSb_3 is much weaker than that of TiCoSb. This failure within CoSb_3 can be explained through the softening of the Sb–Sb bond along with the cleavage of the Co–Sb bond in the interface. The failure mechanism the CoSb_3/TiCoSb interface is similar to that of bulk CoSb_3, but the ideal tensile strength and failure strain of the CoSb_3/TiCoSb interface are much lower than those of bulk CoSb_3. This can be attributed to the weakened stiffness of the Co–Sb framework due to structural rearrangement near the interfacial region

Intrinsic mechanical behavior of MgAgSb thermoelectric material: An ab initio study

α-MgAgSb based thermoelectric (TE) device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ∼8.5% under a temperature difference of 225 K. However, the mechanical behavior of α-MgAgSb is another serious consideration for its engineering applications. Here, we apply density functional theory (DFT) simulations to examine the intrinsic mechanical properties of all three MgAgSb phases, including elastic properties, shear-stress – shear-strain relationships, deformation and failure mechanism under ideal shear and biaxial shear conditions. We find that the ideal shear strength of α-MgAgSb is 3.25 GPa along the most plausible (100) slip system. This strength is higher than that of β-MgAgSb (0.80 GPa) and lower than that of γ-MgAgSb (3.43 GPa). The failure of α-MgAgSb arises from the stretching and breakage of Mg-Sb bond α-MgAgSb under pure shear load, while it arises from the softening of Mg-Ag bond and the breakage of Ag-Sb bond under biaxial shear load. This suggests that the deformation mechanism changes significantly under different loading conditions