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Smart City has become the direction of the development of city. Telemedicine is an important part of Smart City. Telemedicine always provides clinical health care according to the medical images of the patient. High resolution images are expected for remote diagnosis. Super-resolution technology can improve the resolution of medical images. Recently, sparse coding based super-resolution has attracted more attentions. Sparse coding based super-resolution tries to find the sparse representation of low-resolution (LR) image patches from low resolution dictionary, then reconstructs high-resolution (HR) image patches using sparse representation and HR dictionary. In this paper, we propose a sparse-based scheme for medical image super-resolution. First, we jointly divide the training patches into several clusters. Multiple dictionaries are learned from each cluster to collectively provide the least super-resolution error for the training patches. Second, random forest is trained based on the training patches and their cluster labels. Finally, for an input LR image patches, we use trained random forest to determine which cluster the patch belong to, then use the corresponding dictionary to reconstruct the patch. Thus, all the input LR patches are reconstructed with smallest error. All the reconstructed HR patches are synthesized into a completed HR image. The proposed scheme is applied to test a set of medical images. Experimental results show that both objective evaluation (PSNR) and subjective evaluation (visual effect) are improved when compare to other example-based methods.

In this work, the stability of unpackaged CdTe solar cells with different configurations was investigated according to the International Electrotechnical Commission IEC 61215-2016. The measurements of thermal cycling from -40°C to +85°C and 24-hour temperature cycling from -40°C to +85°C withstanding the effects of 20-hour penetration of 85°C were carried out in CdS/CdTe solar cells with structures of FTO/CdS/CdTe/Au, FTO/CdS/CdTe/back contact/Au, and FTO/MZO/CdS/CdTe/back contact/Au, respectively. The performances of these cells before and after the thermal aging experiments were investigated by using light and dark I‐V together with C‐V. The results reveal varied performance degradation before and after thermal aging in the cells with different structures. Among these, the most deteriorated device is the one without back contact (BC), whose efficiency decreased by 25.12% after thermal cycling accompanying an obvious roll-over phenomenon when forward bias was greater than open circuit voltage. On the contrary, the reduction in the efficiency was about 16.80% in the case cells with BC, and the roll-over phenomenon was not so significant. Furthermore, for the devices with optimized front contact of FTO/MZO, the thermal stability was improved obviously. Interestingly, short-circuit current density associated with the carrier concentration of cells remained relatively small variations compared with the change of Voc and fill factor. All the results indicated that an efficient back contact layer and an optimized front electrode were the indispensable structural elements to attain high stabilization in the CdS/CdTe solar cells.

Video transmission over packet-switched networks usually suffers from packet losses. The use of the prediction loop in video coding will cause these errors to propagate to subsequent frames, and thus significantly impacts on the received video quality. With the increasing number of cameras to capture the scene, robustly delivering multi-view video over error-prone channels becomes a rather challenging task. A rate-distortion optimization algorithm is proposed to improve error resilience for multi-view video transmission. A recursive model to estimate the end-to-end distortion is developed for multiview video coding, in which the distortion model explicitly takes into consideration the inherent error resilience property of the hierarchical bi-prediction structure. Based on the proposed distortion model, end-to-end rate-distortion optimization criterion is employed to perform coding mode switching. Extensive experimental results demonstrate significant performance gains can be achieved for multi-view video communication against transmission errors.

The application of thinner cadmium sulfide (CdS) window layer is a feasible approach to improve the performance of cadmium telluride (CdTe) thin film solar cells. However, the reduction of compactness and continuity of thinner CdS always deteriorates the device performance. In this work, transparent Al2O3 films with different thicknesses, deposited by using atomic layer deposition (ALD), were utilized as buffer layers between the front electrode transparent conductive oxide (TCO) and CdS layers to solve this problem, and then, thin-film solar cells with a structure of TCO/Al2O3/CdS/CdTe/BC/Ni were fabricated. The characteristics of the ALD-Al2O3 films were studied by UV&ndash, visible transmittance spectrum, Raman spectroscopy, and atomic force microscopy (AFM). The light and dark J&ndash, V performances of solar cells were also measured by specific instrumentations. The transmittance measurement conducted on the TCO/Al2O3 films verified that the transmittance of TCO/Al2O3 were comparable to that of single TCO layer, meaning that no extra absorption loss occurred when Al2O3 buffer layers were introduced into cells. Furthermore, due to the advantages of the ALD method, the ALD-Al2O3 buffer layers formed an extremely continuous and uniform coverage on the substrates to effectively fill and block the tiny leakage channels in CdS/CdTe polycrystalline films and improve the characteristics of the interface between TCO and CdS. However, as the thickness of alumina increased, the negative effects of cells were gradually exposed, especially the increase of the series resistance (Rs) and the more serious &ldquo, roll-over&rdquo, phenomenon. Finally, the cell conversion efficiency (&eta, ) of more than 13.0% accompanied by optimized uniformity performances was successfully achieved corresponding to the 10 nm thick ALD-Al2O3 thin film.