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Progress in Electromagnetic Research Symposium (PIERS)

作者： Yue Ma Bo Wu Changqing Liu Xianliang Wu Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

This paper presents a low-profile broadband circularly polarized metasurface antenna based on CPW feed. The antenna works in the 3.9-8.5 GHz frequency band, the metasurface consists of $5\times 5$ square cut corner metal patches printed on the upper surface of the dielectric substrate. In order to make the metasurface have the same characteristics for X polarization and Y polarization, the structure is designed to be symmetric in the slant -45° direction, and the size of the cut angle is changed to generate a circularly polarized wave. According to the phase of the incident wave at different positions on the metasurface, the distance between the 9 radiation elements at the center of the metasurface is 0.3 mm, and the distance between the 16 radiation elements in the outermost layer is 0.4 mm, so as to obtain a more suitable phase compensation. The lower surface of the dielectric substrate adopts a CPW coupling aperture structure as a feed source, and the coupling aperture adopts a stair-shape structure to achieve broadband impedance matching, and the stair-shape aperture is attached to the end of the CPW. The proposed antenna has a simple structure and a low profile, which can be realized by a single-layer printed circuit board (PCB) substrate. To verify the simulation results, a model antenna with an overall size of 0.9$\lambda_{0}$× 0.9$\lambda_{0}$× 0.06$\lambda_{0}$, where $\lambda_{0}$ is the free-space wavelength at 5 GHz, is fabricated. The measurement results show that the -10dB return loss bandwidth reaches 72.8%, the circular polarization axis ratio (AR) is less than 3 dB with a bandwidth of 21.6%, and the highest gain reaches 8.34 dBi, which is almost consistent with the simulation results.

关键词： Antenna measurements Polarization Bandwidth Apertures Metasurfaces Antenna feeds Loss measurement

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Design of Miniaturized UWB Antenna with Rectangular Slot

Design of Miniaturized UWB Antenna with Rectangular Slot

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Minquan Li Ziyun Tu Ran Zhao Guangxiu Zhao Yajing Yan Xiaming Mo Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

A miniaturized ultra-wideband (UWB) antenna with excellent performance is designed in this paper. The antenna is based on hexagonal metal patch, and a circular arc structure is added on the top of the antenna, which widens the effective frequency band of the antenna. The current path is changed by opening rectangular slots on the surface and bottom of the antenna, which greatly improves the in-band characteristics of the antenna. The size of the antenna is 29mm × 31 mm × 1.5 mm after continuous optimization with HFSS. The final test results show that the impedance bandwidth of the antenna less than -10 dB is 3.5 GHz ∼ 19.5 GHz, and it has good radiation characteristics in this frequency band range. The antenna achieves the design goal of miniaturization and UWB, and has a good application prospect in communication system.

关键词： Surface impedance Slot antennas Simulation Ultra wideband communication Metals Bandwidth Ultra wideband antennas

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A Miniaturized Bandpass Filter Based on Hexagonal Resonator

A Miniaturized Bandpass Filter Based on Hexagonal Resonator

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Minquan Li Yajing Yan Ran Zhao Baokun Jin Man Zhang Guangxiu Zhao Xiaming Mo Ziyun Tu Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

This paper proposes a miniaturized bandpass filter (BPF) based on hexagonal resonator. Compared with the rectangular filter structure the hexagonal structure is compact, which can realize the miniaturization of the filter. The Y-shape branches are added to the three inner corners of the hexagon which are not adjacent to each other. At the same time, the input/output ports (I/O ports) position of is changed, two transmission zeros (TZs) are introduced at the high frequency band, and the size of the filter is reduced to achieve further miniaturization. In order to obtain better selectivity at low frequency, a split-ring resonator (SRR) is etched on the ground plane, and a TZ is introduced at low frequency. The simulation results show that the filter designed in this paper has a center frequency of 7.3 GHz along with a fractional bandwidth of 7.8%, which achieves a minimum insertion loss of 0.43 dB in the passband and a return loss better than 20 dB, three transmission zeros are introduced at 6.61 GHz, 8.06 GHz and 10.04 GHz, respectively. The final size of this filter is $0.23\lambda_{g}*0.29\lambda_{g}$, a reduction of 48.2%.

关键词： Band-pass filters Simulation Resonator filters Resonant frequency Insertion loss Propagation losses Filtering theory

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The Invention Relates to a Wideband Circularly Polarized Metasurface Antenna

The Invention Relates to a Wideband Circularly Polarized Met...

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Mengying Dong Xianliang Wu Yue Ma Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

Aiming at the single characteristic of traditional antenna bandwidth and working polarization state, a broadband circularly polarized antenna based on metamaterial surface is proposed. The antenna is composed of a rectangular microstrip antenna and an upper metasurface. The distance between the two is h. The metasurface is composed of $5\times 5$ square metal elements with equiangular structures on both sides. The linearly polarized rectangular microstrip antenna as the feeding antenna radiates linearly polarized electromagnetic waves, and the metasurface converts the linearly polarized electromagnetic waves radiated by the feeding antenna into circularly polarized electromagnetic waves. This paper analyzes the principle of circular polarization after the antenna is loaded with a metasurface. The simulation software HFSS is used to perform parameter scanning and simulation analysis on the antenna with the size of 0.88$\lambda\times 0.88$$\lambda\times 0.04$$\lambda \mathrm{m}^{3}$ and the center frequency of 8.5 GHz. The results show that the impedance bandwidth of the atenna S 11

关键词： Polarization Microstrip antennas Bandwidth Metasurfaces Antenna feeds Broadband antennas Microstrip

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Highly Selective UWB Bandpass Filter with Dual Notch Bands Using Stub Loaded Multiple-mode Resonator

Highly Selective UWB Bandpass Filter with Dual Notch Bands U...

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Guangxiu Zhao Minquan Li Ran Zhao Ziyun Tu Yajing Yan Xiaming Mo Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

In this paper, a low-loss ultra-wideband (UWB) bandpass filter with high selectivity and multiple notch bands is proposed. The filter is based on multi-mode resonator (MMR) which mainly consists of a step impedance transmission line that excites several resonant modes. The MMR structure is loaded a T-shaped open-circuited stub which generate two transmission zeros at the edge of the passband to improve selectivity. Meanwhile, MMR structure is also loaded two pairs of short high impedance stubs to extend the upper stopband of the filter. In addition, to address the in-band interference issues, by coupling a tunable parasitic unit to generate dual band notches at 5.8GHz (WLAN) and 8.1 GHz (X-band). Simulated result indicates that the designed filter’s passband is from 3.18 GHz to 10.67 GHz, the insertion loss is lower than 0.5 dB and its 3 dB relative bandwidth is 108.1%. At the same time, the filter has a high selectivity (30dB skirt factor is 0.917) and a stopband of up to 20 GHz (S 21 < −15dB).

关键词： Band-pass filters Couplings Wireless LAN Resonator filters Insertion loss Bandwidth Filtering theory

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A Novel Design of Wide Stopband Filter with High Selectivity

A Novel Design of Wide Stopband Filter with High Selectivity

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Minquan Li Xiaming Mo Ran Zhao Yajing Yan Guangxiu Zhao Ziyun Tu Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9781665409889

In this paper, a wide stopband bandpass filter with high selectivity is designed, which uses three stepped impedance resonators to form the main body of the filter, which improves the stopband width of the filter, and has a wide stopband to 3f 0 . The parasitic passband of the filter is suppressed by etching the double T-shaped defected ground structure that changes the current distribution on the floor, generate a band gap with band-stop characteristics, the stopband width is over 4f 0 . Transmission zero is introduced by cross coupling resonance. There are two coupling paths for the signal from the input to output, one transmission zero is obtained on the upper stopband, then the selectivity of the filter is improved obviously. The simulation results show that the return loss of the filter can reach 46 dB and the insertion loss is less than 0.5 dB in the passband of 4.8 GHz-5.0 GHz. The stopband attenuation of 5.8 GHz-20 GHz is better than 20 dB. The rectangular coefficient of 30 dB/3dB is 3.72, and the size is 12 * 45.9 mm 2 .

关键词： Band-pass filters Couplings Photonic band gap Simulation Resonator filters Insertion loss Attenuation

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Rethink Video Retrieval Representation for Video Captioning

SSRN

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SSRN 2024年

作者： Tian, Mingkai Li, Guorong Qi, Yuankai Wang, Shuhui Sheng, Quan Z. Huang, Qingming School of Computer Science and Technology Key Lab of Big Data Mining and Knowledge Management University of Chinese Academy of Sciences China School of Computing Macquarie University Australia Key Laboratory of Intelligent Information Processing Institute of Computer Technology Chinese Academy of Sciences China

Video captioning, a challenging task targeting the automatic generation of accurate and comprehensive descriptions based on video content, has witnessed substantial success recently driven by bridging video representations and textual semantics. Inspired by the nature of the video retrieval task, which learns visual features strongly related to text queries, we propose to take advantage of visual representation learning from the video retrieval framework to tackle video captioning tasks. However, a simple direct application of video retrieval models performs poorly due to the weak ability to capture sufficient video details and temporal information required for video captioning. To increase the attention on details, we propose a learnable token shift module, which flexibly captures subtle movements in local regions across the temporal sequence. Furthermore, we devise a Refineformer, which learns to integrate local video tokens strongly related to desired captions via a cross-attention mechanism. Extensive experiments on MSVD, MSR-VTT and VATEX demonstrate the favorable performance of our method. © 2024, The Authors. All rights reserved.

关键词： Semantics

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Synthesize, Diagnose, and Optimize: Towards Fine-Grained Vision-Language Understanding

arXiv

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arXiv 2023年

作者： Peng, Wujian Xie, Sicheng You, Zuyao Lan, Shiyi Wu, Zuxuan Shanghai Key Lab of Intell. Info. Processing School of CS Fudan University China Shanghai Collaborative Innovation Center of Intelligent Visual Computing China NVIDIA United States

Vision language models (VLM) have demonstrated remarkable performance across various downstream tasks. However, understanding fine-grained visual-linguistic concepts, such as attributes and inter-object relationships, remains a significant challenge. While several benchmarks aim to evaluate VLMs in finer granularity, their primary focus remains on the linguistic aspect, neglecting the visual dimension. Here, we highlight the importance of evaluating VLMs from both a textual and visual perspective. We introduce a progressive pipeline to synthesize images that vary in a specific attribute while ensuring consistency in all other aspects. Utilizing this data engine, we carefully design a benchmark, SPEC, to diagnose the comprehension of object size, position, existence, and count. Subsequently, we conduct a thorough evaluation of four leading VLMs on SPEC. Surprisingly, their performance is close to random guess, revealing significant limitations. With this in mind, we propose a simple yet effective approach to optimize VLMs in fine-grained understanding, achieving significant improvements on SPEC without compromising the zero-shot performance. Results on two additional fine-grained benchmarks also show consistent improvements, further validating the transferability of our approach. Code and data are available at https://***/wjpoom/SPEC. Copyright © 2023, The Authors. All rights reserved.

关键词： Zero-shot learning

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BEVNeXt: Reviving Dense BEV Frameworks for 3D Object Detection

arXiv

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arXiv 2023年

作者： Li, Zhenxin Lan, Shiyi Alvarez, Jose M. Wu, Zuxuan Shanghai Key Lab of Intell. Info. Processing School of CS Fudan University China Shanghai Collaborative Innovation Center of Intelligent Visual Computing China NVIDIA United States

Recently, the rise of query-based Transformer decoders is reshaping camera-based 3D object detection. These query-based decoders are surpassing the traditional dense BEV (Bird’s Eye View)-based methods. However, we argue that dense BEV frameworks remain important due to their outstanding abilities in depth estimation and object localization, depicting 3D scenes accurately and comprehensively. This paper aims to address the drawbacks of the existing dense BEV-based 3D object detectors by introducing our proposed enhanced components, including a CRF-modulated depth estimation module enforcing object-level consistencies, a long-term temporal aggregation module with extended receptive fields, and a two-stage object decoder combining perspective techniques with CRF-modulated depth embedding. These enhancements lead to a "modernized" dense BEV framework dubbed BEVNeXt. On the nuScenes benchmark, BEVNeXt outperforms both BEV-based and query-based frameworks under various settings, achieving a state-of-the-art result of 64.2 NDS on the nuScenes test set. Code will be available at https://***/woxihuanjiangguo/BEVNeXt. Copyright © 2023, The Authors. All rights reserved.

关键词： Object detection

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T-GraphDTA: A Drug-Target Binding Affinity Prediction Framework Based on Protein Pre-training Model and Hybrid Graph Neural Network 1st

T-GraphDTA: A Drug-Target Binding Affinity Prediction Framew...

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1st International Conference on Applied Intelligence, ICAI 2023

作者： Wu, Yijia Lin, Yanmei Peng, Yuzhong Zhang, Ru Cai, Li Key Lab of Scientific Computing and Intelligent Information Processing Nanning Normal University Guangxi Nanning530000 China Guangxi Academy of Sciences Guangxi Nanning530007 China School of Software Yunnan University Yunnan Kunming650000 China

ISBN: (纸本)9789819709021

Drug-target affinity (DTA) prediction is an important task in computer-aided drug design and drug repositioning, which can speed up drug development and reduce resource consumption. Researchers have explored some deep learning-based methods to improve DTA prediction in recent years, demonstrating the great potential of deep learning in DTA prediction. They have developed several molecular representation learning methods for drug compounds in deep learning-based DTA prediction methods. However, most of the existing deep learning-based DTA prediction models use one-hot encoding-based methods for protein representation learning, or use recursive neural network-based methods for learning feature representations from raw protein sequences. These may affect the ability of the DTA prediction model to learn the potential features of the protein, thus weakening the predictive power of the model. To tackle this problem, we developed a novel protein pre-training method (PTR) for protein representation learning, then proposed a DTA prediction framework, called Transformer-Graph drug-target affinity prediction (T-GraphDTA), based on PTR and hybrid graph neural network. The hybrid graph neural network is mainly responsible for molecular presentation learning of drugs. Extensive experiments were conducted on four benchmark datasets of drug-target binding affinity, comparing T-GraphDTA against state-of-the-art models. The experimental results show that T-GraphDTA achieves significantly better performance than state-of-the-art models on all four benchmark datasets. It indicates that T-GraphDTA is expected to be an excellent practical tool for predicting the affinity of drug-target pairs. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Forecasting

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