Hyperspectral imaging is unable to acquire images with high resolution in both spatial and spectral dimensions yet due to physical hardware limitations. It can only produce low spatial resolution images in most cases and thus hyperspectral image (HSI) spatial super-resolution is important. Recently, deep learning based methods for HSI spatial super-resolution have been actively exploited. However, existing methods do not focus on structural spatial-spectral correlation and global correlation along spectra, which cannot fully exploit useful information for super-resolution. Also, some of the methods are straight forward extension of RGB super-resolution methods, which have fixed number of spectral channels and cannot be generally applied to hyperspectral images whose number of channels varies. Furthermore, unlike RGB images, existing HSI datasets are small and limit the performance of learning based methods. In this paper, we design a bidirectional 3D quasi-recurrent neural network for HSI super-resolution with arbitrary number of bands. Specifically, we introduce a core unit that contains a 3D convolutional module and a bidirectional quasi-recurrent pooling module to effectively extract structural spatial-spectral correlation and global correlation along spectra, respectively. By combining domain knowledge of HSI with a novel pre-training strategy, our method can be well generalized to remote sensing HSI datasets with limited number of training data. Extensive evaluations and comparisons on HSI super-resolution demonstrate improvements over state-of-the-art methods, in terms of both restoration accuracy and visual quality.

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Abstract:In this study, we proposed an innovative oxidation-absorption method for low-temperature denitrification (160-240 • C), in which NO is initially catalytically oxidized by hydrogen peroxide (H 2 O 2 ) vapor over titania-based catalysts, and the oxidation products are then absorbed by NaOH solution. The effects of flue gas temperature, molar H 2 O 2 /NO ratio, gas hourly space velocity (GHSV), and Fe substitution amounts of Fe/TiO 2 catalysts on the denitrification efficiency were investigated by a well-designed experiment. The results indicated that the Fe/TiO 2 catalyst exhibited a combination of remarkable activity and deep oxidation ability (NO converted into harmless NO 3 − ). In order to comprehend the functional mechanism of the Fe dopant's local environment in TiO 2 support, the promotional effect of the calcination temperature of Fe/TiO 2 on the denitration performance was also studied. A tentative synergetic mechanism could be interpreted from two aspects: (1) Fe 3+ as a substitute of Ti 4+ , leading to the formation of enriched oxygen vacancies at the surface, could significantly improve the adsorption efficiency of •OH; (2) the isolated surface Fe ion holds a strong adsorption affinity for NO, such that the adsorbed NO could be easily oxidized by the pre-formed •OH. This process offers a promising alternative for current denitrification technology.

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Optical tracking systems are widely adopted in surgical navigation. An optical tracking system is designed based on the principle of stereo vision with high-precision and low cost. This system uses optical infrared LEDs that are installed on the surgical instrument as markers and a near-infrared filter is added in front of the Bumblebee2 stereo camera lens to eliminate the interference of ambient light. The algorithm based on the region growing method is designed and used for the marker’s pixel coordinates’ extraction. In this algorithm, the singular points are eliminated and the gray centroid method is applied to solve the pixel coordinate of the marker’s center. Then, the marker’s matching algorithm is adopted and three-dimensional coordinates’ reconstruction is applied to derive the coordinates of the surgical instrument tip in the world coordinate system. In the simulation, the stability, accuracy, rotation tests, and the tracking angle and area range were carried out for a typical surgical instrument and the miniature surgical instrument. The simulation results show that the proposed optical tracking system has high accuracy and stability. It can meet the requirements of surgical navigation.