A Local Texture-Based Superpixel Feature Coding for Saliency Detection Combined with Global Saliency

Because saliency can be used as the prior knowledge of image content, saliency detection has been an active research area in image segmentation, object detection, image semantic understanding and other relevant image-based applications. In the case of saliency detection from cluster scenes, the salient object/region detected needs to not only be distinguished clearly from the background, but, preferably, to also be informative in terms of complete contour and local texture details to facilitate the successive processing. In this paper, a Local Texture-based Region Sparse Histogram (LTRSH) model is proposed for saliency detection from cluster scenes. This model uses a combination of local texture patterns and color distribution as well as contour information to encode the superpixels to characterize the local feature of image for region contrast computing. Combining the region contrast as computed with the global saliency probability, a full-resolution salient map, in which the salient object/region detected adheres more closely to its inherent feature, is obtained on the bases of the corresponding high-level saliency spatial distribution as well as on the pixel-level saliency enhancement. Quantitative comparisons with five state-of-the-art saliency detection methods on benchmark datasets are carried out, and the comparative results show that the method we propose improves the detection performance in terms of corresponding measurements

Bottom-up synthesis of SnTe-based thermoelectric composites

There is a need for the development of lead-free thermoelectric materials for medium-/high-temperature applications. Here, we report a thiol-free tin telluride (SnTe) precursor that can be thermally decomposed to produce SnTe crystals with sizes ranging from tens to several hundreds of nanometers. We further engineer SnTe–Cu2SnTe3 nanocomposites with a homogeneous phase distribution by decomposing the liquid SnTe precursor containing a dispersion of Cu1.5Te colloidal nanoparticles. The presence of Cu within the SnTe and the segregated semimetallic Cu2SnTe3 phase effectively improves the electrical conductivity of SnTe while simultaneously reducing the lattice thermal conductivity without compromising the Seebeck coefficient. Overall, power factors up to 3.63 mW m–1 K–2 and thermoelectric figures of merit up to 1.04 are obtained at 823 K, which represent a 167% enhancement compared with pristine SnTe

Engineering of thermoelectric composites based on silver selenide in aqueous solution and ambient temperature

The direct, solid state, and reversible conversion between heat and electricity using thermoelectric devices finds numerous potential uses, especially around room temperature. However, the relatively high material processing cost limits their real applications. Silver selenide (Ag2Se) is one of the very few n-type thermoelectric (TE) materials for room-temperature applications. Herein, we report a room temperature, fast, and aqueous-phase synthesis approach to produce Ag2Se, which can be extended to other metal chalcogenides. These materials reach TE figures of merit (zT) of up to 0.76 at 380 K. To improve these values, bismuth sulfide (Bi2S3) particles also prepared in an aqueous solution are incorporated into the Ag2Se matrix. In this way, a series of Ag2Se/Bi2S3 composites with Bi2S3 wt % of 0.5, 1.0, and 1.5 are prepared by solution blending and hot-press sintering. The presence of Bi2S3 significantly improves the Seebeck coefficient and power factor while at the same time decreasing the thermal conductivity with no apparent drop in electrical conductivity. Thus, a maximum zT value of 0.96 is achieved in the composites with 1.0 wt % Bi2S3 at 370 K. Furthermore, a high average zT value (zTave) of 0.93 in the 300–390 K range is demonstrated

Thermoelectric performance of surface-engineered Cu1.5–xTe–Cu2Se nanocomposites

Cu2–xS and Cu2–xSe have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, Cu2–xTe, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, zT, particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of Cu1.5–xTe–Cu2Se nanocomposites by consolidating surface-engineered Cu1.5Te nanocrystals. This surface engineering strategy allows for precise adjustment of Cu/Te ratios and results in a reversible phase transition at around 600 K in Cu1.5–xTe–Cu2Se nanocomposites, as systematically confirmed by in situ high-temperature X-ray diffraction combined with differential scanning calorimetry analysis. The phase transition leads to a conversion from metallic-like to semiconducting-like TE properties. Additionally, a layer of Cu2Se generated around Cu1.5–xTe nanoparticles effectively inhibits Cu1.5–xTe grain growth, minimizing thermal conductivity and decreasing hole concentration. These properties indicate that copper telluride based compounds have a promising thermoelectric potential, translated into a high dimensionless zT of 1.3 at 560 K

Thermoelectric Performance of Surface-Engineered Cu_{1.5–<i>x</i>}Te–Cu₂Se Nanocomposites

Cu2–xS and Cu2–xSe have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, Cu2–xTe, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, zT, particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of Cu1.5–xTe–Cu2Se nanocomposites by consolidating surface-engineered Cu1.5Te nanocrystals. This surface engineering strategy allows for precise adjustment of Cu/Te ratios and results in a reversible phase transition at around 600 K in Cu1.5–xTe–Cu2Se nanocomposites, as systematically confirmed by in situ high-temperature X-ray diffraction combined with differential scanning calorimetry analysis. The phase transition leads to a conversion from metallic-like to semiconducting-like TE properties. Additionally, a layer of Cu2Se generated around Cu1.5–xTe nanoparticles effectively inhibits Cu1.5–xTe grain growth, minimizing thermal conductivity and decreasing hole concentration. These properties indicate that copper telluride based compounds have a promising thermoelectric potential, translated into a high dimensionless zT of 1.3 at 560 K