135 research outputs found
Analysis of Multi-Element Blended Course Teaching and Learning Mode Based on Student-Centered Concept under the Perspective of “Internet+”
The integration of Internet and education has changed students’ learning environment and affected their learning behavior, which poses a greater challenge to the traditional teaching mode. Through the SWOT analysis of the “student centered” multi-element blended teaching mode in the era of “Internet + education”, it is concluded that the adaptability of learners themselves and the mismatch between teachers’ educational ideas and this teaching model delay the development of education to a certain extent. Some suggestions are put forward, such as strengthening the supervision and guidance, implementing the teaching and learning model scientifically, improving teachers’ ideology and comprehensive quality, and making full use of the characteristics of Internet opening, sharing and collaboration to construct the public service system and platform of national educational resources
Real-space sampling of terahertz waveforms with sub-nanometer spatial resolution
Terahertz scanning tunneling microscopy (THz-STM) has emerged as a potent
technique for probing ultrafast nanoscale dynamics with exceptional
spatiotemporal precision, whereby the acquisition of THz near-field waveforms
holds paramount significance. While substantial efforts have been dedicated to
retrieving the waveform utilizing the photoemission current or a molecular
sensor, these methods are challenged by intensive thermal effects or complex
sample preparations. In this study, we introduce a universal approach for
real-time characterization of THz near-field waveforms within the tunnel
junction, achieving sub-nanometer spatial resolution. Utilizing the gating
mechanism intrinsic to the STM junction, coherent scanning of a gated strong
THz pulse over a weak THz pulse is achieved, facilitating direct measurement of
the waveform. Notably, employing a custom-built Carrier-Envelope Phase (CEP)
shifter, THz-CEP has been successfully characterized in the tunnel junction.
Furthermore, THz spectral imaging through point-to-point sampling of THz
waveforms on a triatomic Au (111) step has been demonstrated, highlighting the
sub-nanometer spatial resolution of our sampling methodology.Comment: 26 pages and 4 figures for the manuscript; 16 pages and 7 figures for
the Supporting Informatio
Multi-energy X-ray linear-array detector enabled by the side-illuminated metal halide scintillator
Conventional scintillator-based X-ray imaging typically captures the full
spectral of X-ray photons without distinguishing their energy. However, the
absence of X-ray spectral information often results in insufficient image
contrast, particularly for substances possessing similar atomic numbers and
densities. In this study, we present an innovative multi-energy X-ray
linear-array detector that leverages side-illuminated X-ray scintillation using
emerging metal halide Cs3Cu2I5. The negligible self-absorption characteristic
not only improves the scintillation output but is also beneficial for improving
the energy resolution for the side-illuminated scintillation scenarios. By
exploiting Beer's law, which governs the absorption of X-ray photons with
different energies, the incident X-ray spectral can be reconstructed by
analyzing the distribution of scintillation intensity when the scintillator is
illuminated from the side. The relative error between the reconstructed and
measured X-ray spectral was less than 5.63 %. Our method offers an additional
energy-resolving capability for X-ray linear-array detectors commonly used in
computed tomography (CT) imaging setups, surpassing the capabilities of
conventional energy-integration approaches, all without requiring extra
hardware components. A proof-of-concept multi-energy CT imaging system
featuring eight energy channels was successfully implemented. This study
presents a simple and efficient strategy for achieving multi-energy X-ray
detection and CT imaging based on emerging metal halides
SPHR-SAR-Net: Superpixel High-resolution SAR Imaging Network Based on Nonlocal Total Variation
High-resolution is a key trend in the development of synthetic aperture radar
(SAR), which enables the capture of fine details and accurate representation of
backscattering properties. However, traditional high-resolution SAR imaging
algorithms face several challenges. Firstly, these algorithms tend to focus on
local information, neglecting non-local information between different pixel
patches. Secondly, speckle is more pronounced and difficult to filter out in
high-resolution SAR images. Thirdly, the process of high-resolution SAR imaging
generally involves high time and computational complexity, making real-time
imaging difficult to achieve. To address these issues, we propose a Superpixel
High-Resolution SAR Imaging Network (SPHR-SAR-Net) for rapid despeckling in
high-resolution SAR mode. Based on the concept of superpixel techniques, we
initially combine non-convex and non-local total variation as compound
regularization. This approach more effectively despeckles and manages the
relationship between pixels while reducing bias effects caused by convex
constraints. Subsequently, we solve the compound regularization model using the
Alternating Direction Method of Multipliers (ADMM) algorithm and unfold it into
a Deep Unfolded Network (DUN). The network's parameters are adaptively learned
in a data-driven manner, and the learned network significantly increases
imaging speed. Additionally, the Deep Unfolded Network is compatible with
high-resolution imaging modes such as spotlight, staring spotlight, and sliding
spotlight. In this paper, we demonstrate the superiority of SPHR-SAR-Net
through experiments in both simulated and real SAR scenarios. The results
indicate that SPHR-SAR-Net can rapidly perform high-resolution SAR imaging from
raw echo data, producing accurate imaging results
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