Most existing person re-identification (ReID) methods rely only on the spatial appearance information from either one or multiple person images, whilst ignore the space-time cues readily available in video or image-sequence data. Moreover, they often assume the availability of exhaustively labelled cross-view pairwise data for every camera pair, making them non-scalable to ReID applications in real-world large scale camera networks. In this work, we introduce a novel video based person ReID method capable of accurately matching people across views from arbitrary unaligned image-sequences without any labelled pairwise data. Specifically, we introduce a new space-time person representation by encoding multiple granularities of spatio-temporal dynamics in form of time series. Moreover, a Time Shift Dynamic Time Warping (TS-DTW) model is derived for performing automatically alignment whilst achieving data selection and matching between inherently inaccurate and incomplete sequences in a unified way. We further extend the TS-DTW model for accommodating multiple feature-sequences of an image-sequence in order to fuse information from different descriptions. Crucially, this model does not require pairwise labelled training data (i.e. unsupervised) therefore readily scalable to large scale camera networks of arbitrary camera pairs without the need for exhaustive data annotation for every camera pair. We show the effectiveness and advantages of the proposed method by extensive comparisons with related state-of-the-art approaches using two benchmarking ReID datasets, PRID2011 and iLIDS-VID.

In this paper, a multi-layered metallic structure is proposed, which consists of split-ring resonators on both sides of two dielectric substrates. Numerical results reveal that the structure realizes a high magnitude of 0.94, three bands and broadband (more than 8 GHz) asymmetric transmission for linearly polarized wave. These properties are not observed in previous works. In order to better know these transmission properties, the Fabry-Perot like resonance model has been introduced to analyze the enhancement mechanism of asymmetric transmission in the multi-layered structure. The physical mechanism of linearly polarized wave conversion and asymmetric transmission based on electric fields and currents distribution is also analyzed in detail, respectively.

A two-dimensional chiral structure with an h-shape and H-shape on opposing sides of a dielectric layer is proposed that can realize simultaneously dual-band asymmetric transmission of linearly and circularly polarized waves in the near-infrared band. Meanwhile, the structure realizes a maximum asymmetric transmission of 0.56 and 0.30 for linearly and circularly polarized waves, respectively, at the resonant frequency. These results have been analyzed with simulations in detail. The physical mechanism of linearly and circularly polarized wave transmission and conversion based on current distribution and electric fields is also investigated.

Hard X-ray Imager (HXI) is one of the three scientific instruments onboard the Advanced Spacebased Solar Observatory (ASO-S) mission, which is proposed for the 25th solar maximum by the Chinese solar community. HXI is designed to investigate the non-thermal high-energy electrons accelerated in solar flares by providing images of solar flaring regions in the energy range from 30 keV to 200 keV. The imaging principle of HXI is based on spatially modulated Fourier synthesis and utilizes about 91 sets of bi-grid sub-collimators and corresponding LaBr3 detectors to obtain Fourier components with a spatial resolution of about 3 arcsec and a time resolution better than 0.5 s. An engineering prototype has been developed and tested to verify the feasibility of design. In this paper, we present background, instrument design and the development and test status of the prototype.

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Nanoscale active devices, such as all-optical modulators and electro-optical transducers, can be implemented in heterostructures that integrate plasmonic nanostructures with functional active materials. Here, we demonstrate control over absorption properties in such a heterostructure by coupling the localized surface plasmon resonance (LSPR) of gold nanoantennas to a phase change material (PCM), Ge2Sb2Te5 (GST). The peak absorption of this hybrid absorber approaches near unity at resonance due to the simultaneous excitations of electric and magnetic resonant modes. Moreover, such a hybrid absorber can realize arbitrary wavelength-selective spectral absorption in the mid-infrared region simply by altering the square nanoantennas side length. By controlling the total power of the incident light, the intermediate phases composed of different proportions of the amorphous and crystalline molecules of the GST can be correspondingly tailored, and thus the absorption can be continuously tuned, which provides a flexible and encouraging way to achieve active features once fabricated. Importantly, by converting GST from the amorphous to crystalline state or vice versa, the hybrid absorber can realize bidirectional switching of "ON" and "OFF" states, with an outperformed modulation depth of 98% (or 95%) and extinction ratio of −17.15 dB (or −12.98 dB), respectively, indicating its excellent optical modulation performance. Notably, all the stable and intermediate phases of the GST are stable at room temperature, and therefore no sustained external thermal consumption is needed to maintain a desired absorption band for the hybrid scheme. Additionally, the structure can tolerate a wide range of incident angles as well as show polarization-independent features. With these extraordinary optical responses, the proposed scheme could find potential applications in active photonic devices such as optical modulation, thermal imaging and optical switching.

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