South China University of Technology

About: South China University of Technology is a education organization based out in Guangzhou, China. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 62343 authors who have published 69468 publications receiving 1251592 citations. The organization is also known as: SCUT & Huánán Lǐgōng Dàxué.

High-Gain Filtering Patch Antenna Without Extra Circuit

Abstract: This paper presents a novel kind of patch antenna with high-selectivity filtering responses and high-gain radiation performance. The proposed antenna is mainly composed of a driven patch and a stacked patch, with its entire height being ${0.09\lambda }$ . Three shorting pins and a U-slot are embedded in the driven patch to enhance out-of-band suppression levels and skirt selectivity near the lower band-edge, whereas the stacked patch provides a sharp roll-off rate at the upper band-edge and also an enhanced gain. Without using extra filtering circuits, the proposed antenna exhibits a quasi-elliptic boresight gain response with three radiation nulls. For demonstration, an antenna is implemented covering the LTE band (2.3–2.7 GHz). The antenna achieves an average gain of 9.7 dBi within passband, and out-of-band suppression levels of more than 21 dB.

Model Adaptation: Unsupervised Domain Adaptation Without Source Data

Abstract: In this paper, we investigate a challenging unsupervised domain adaptation setting --- unsupervised model adaptation. We aim to explore how to rely only on unlabeled target data to improve performance of an existing source prediction model on the target domain, since labeled source data may not be available in some real-world scenarios due to data privacy issues. For this purpose, we propose a new framework, which is referred to as collaborative class conditional generative adversarial net to bypass the dependence on the source data. Specifically, the prediction model is to be improved through generated target-style data, which provides more accurate guidance for the generator. As a result, the generator and the prediction model can collaborate with each other without source data. Furthermore, due to the lack of supervision from source data, we propose a weight constraint that encourages similarity to the source model. A clustering-based regularization is also introduced to produce more discriminative features in the target domain. Compared to conventional domain adaptation methods, our model achieves superior performance on multiple adaptation tasks with only unlabeled target data, which verifies its effectiveness in this challenging setting.

Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser

Abstract: Few-layer black phosphorus (BP), as the most alluring graphene analogue owing to its similar structure as graphene and thickness dependent direct band-gap, has now triggered a new wave of research on two-dimensional (2D) materials based photonics and optoelectronics. However, a major obstacle of practical applications for few-layer BPs comes from their instabilities of laser-induced optical damage. Herein, we demonstrate that, few-layer BPs, which was fabricated through the liquid exfoliation approach, can be developed as a new and practical saturable absorber (SA) by depositing few-layer BPs with microfiber. The saturable absorption property of few-layer BPs had been verified through an open-aperture z-scan measurement at the telecommunication band. The microfiber-based BP device had been found to show a saturable average power of ~4.5 mW and a modulation depth of 10.9%, which is further confirmed through a balanced twin detection measurement. By integrating this optical SA device into an erbium-doped fiber laser, it was found that it can deliver the mode-locked pulse with duration down to 940 fs with central wavelength tunable from 1532 nm to 1570 nm. The prevention of BP from oxidation through the "lateral interaction scheme" owing to this microfiber-based few-layer BP SA device might partially mitigate the optical damage problem of BP. Our results not only demonstrate that black phosphorus might be another promising SA material for ultrafast photonics, but also provide a practical solution to solve the optical damage problem of black phosphorus by assembling with waveguide structures such as microfiber.

A study on the residual stress during selective laser melting (SLM) of metallic powder

Abstract: The complex thermal history of the parts manufactured by selective laser melting (SLM) leads to complex residual stress, having a significant impact on the quality of SLM part. The origin of residual stress was investigated in terms of temperature gradient mechanism. Then, stresses along the height and horizontal directions were measured by X-ray diffraction, and effects of processing parameters on the stress distribution were studied. Results showed that residual stress distribution and evolution along the height direction are affected by the subsequent thermal cycling (STC) significantly. In the horizontal direction, higher energy input and longer track length induce larger residual stress. The stress parallel to the scanning direction is much larger than that perpendicular to the scanning direction, and the peak values of residual stress always occurs at the onset of scanning tracks. Based on this study, corresponding measures can be taken to reduce the residual stress or avoid stress concentration, thereby improving the process stability of SLM.

Donor polymer design enables efficient non-fullerene organic solar cells.

Abstract: In organic photovoltaics, electron acceptors are developed to replace fullerenes, and new donors need to be designed to match these acceptors Here, the authors show that a polymer with strong temperature dependent aggregation and intentionally reduced crystallinity matches non-fullerene acceptors