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372 results on '"Li, Ruiming"'

59. Independently Switchable Rasorber With Wide Transmission and Low-Reflection Bands Under Dual Polarization

Author

Jiang, Hao, Liao, Shaowei, Li, Ruiming, and Xue, Quan

Abstract

Switchable frequency selective rasorbers (FSRs) have gained significant attention for their ability to switch passbands into absorption bands. However, increasing their functionality or switchable state while maintaining stable wideband transmission and low reflection remains challenging. Therefore, this work proposes a three-layer FSR architecture that achieves switchable wide-passband in wide low-reflection bands and state-of-the-art independent switchability under dual polarization. First, for the bottom layer, a second-order inductively coupled frequency selective surface (FSS) with active diode loading on the uppermost layer can switch from wide passband to reflections. Second, for the middle layer, the switchable impedance layer with a low- ${Q}$ parallel resonator can preserve the passband or absorb previous in-band electromagnetic (EM) waves. Third, for the top layer, theoretical analysis confirms that an additional nonswitchable impedance layer must be introduced to achieve extended low reflection bandwidth during various switching states. Note that a polarization-isolated bias network is merged into the structural design to provide polarization-independent switchability for the passband. Finally, experimental results agree with simulations, demonstrating the proposed FSR device exhibits excellent performance, including four switching operating states, a wide 1-dB passband, 45° transmission angular stability, and a consistently wide low-reflection band in all rasorbing or absorbing states.

Published
2024
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60. Investigation of the Physicochemical Interactions and Modification Effects of Polyurethane on Asphalt Binder

Author

Li, Ruiming, Zhu, Xiaoxu, and Wang, Yuhong

Abstract

Polyurethane (PU) is a synthetic polymeric material with excellent mechanical properties and chemical designability. An in-depth understanding of the synergetic effect between polyurethane and asphalt binder is needed to produce durable PU-modified asphalt paving materials. This study focuses on the physicochemical changes, the states of in situ synthesized PU, and the modification effects of PU after PU prepolymers and chain extenders are added into asphalt binder. Investigation methods involve the Fourier transform infrared (FTIR) spectroscopy, partial Corbett separation, confocal fluorescence microscopy, particle size distribution test, rheological test, and theoretical calculation. It was found that the incorporation of PU has no obvious chemical influence on the asphalt binder and the main working principle of PU modification is its physical dispersion in asphalt binder. In situ synthesized PU is uniformly dispersed in asphalt binder and the size distribution of PU particles follows a log-normal distribution. As PU content exceeds 15%, the formed PU particles in asphalt binder are noticeably enlarged. Moreover, PU modification leads to significant improvements in asphalt binder properties, including high-temperature rutting resistance, elastic recovery, and deformation resistance. Rheological experiments and theoretical calculations under the framework of suspension rheology indicate that PU-modified asphalt binder can be reasonably modeled as a bimodal solid particle suspension, and the dynamic viscosity of PU-modified asphalt binder is predominantly determined by the dynamic viscosity of the maltenes and the volume fractions of PU and asphaltenes.

Published
2024
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66. Enhanced Charge Carrier Mobility of Evaporated Sb2Se3 via Post‐Treatment for High‐Speed Photodetection.

Author

Xu, Yalun, Jia, Zhenglin, Li, Ruiming, and Lin, Qianqian

Subjects
CHARGE carrier mobility, CHARGE carriers, SEMICONDUCTOR devices, THIN films, SOLAR cells, PHOTODIODES
Abstract

Benefiting from excellent optoelectronic properties and facile fabrication, Sb2Se3‐based semiconductor devices have drawn great attention in the last decade; in particular, Sb2Se3‐based solar cells and photodetectors have demonstrated decent performance metrics. However, the current research on Sb2Se3 devices is mainly focused on material and device processing and optimization, and few studies have been conducted on charge transport, which is limiting the further development of Sb2Se3‐based devices. To address this issue, post‐treatment techniques are introduced and their influence on the charge carrier dynamics of Sb2Se3 thin films is fully investigated. The charge carrier mobility of evaporated Sb2Se3 thin films is increased by an order of magnitude from 0.02 to 0.4 cm2 V−1 s−1 after the Se post‐treatment. Based on the optimized Sb2Se3 thin films, ultra‐fast photodiodes are further developed and a record‐fast response of 37 ns is achieved. Prototypical devices also demonstrated great potential for high‐speed photodetection in practical applications. [ABSTRACT FROM AUTHOR]

Published
2023
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72. Over 28% efficiency perovskite/Cu(InGa)Se2 tandem solar cells: highly efficient sub-cells and their bandgap matching

Author

Liu, Xinxing, primary, Zhang, Junjun, additional, Tang, Liting, additional, Gong, Junbo, additional, Li, Wang, additional, Ma, Zengyang, additional, Tu, Zexin, additional, Li, Yanyan, additional, Li, Ruiming, additional, Hu, Xuzhi, additional, Shen, Chen, additional, Wang, He, additional, Wang, Zhiping, additional, Lin, Qianqian, additional, Fang, Guojia, additional, Wang, Sheng, additional, Liu, Chang, additional, Zhang, Zengming, additional, Li, Jianmin, additional, and Xiao, Xudong, additional

Published
2023
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80. Modulating the Quantum Efficiency of Sb2S3‐Based Photodiodes Based on Conventional and Inverted Structures.

Author

Li, Ruiming, Zeng, Haiyi, Bai, Songxue, Jia, Zhenglin, Xu, Yalun, Yao, Fang, Liu, Yong, Huang, Huiming, Li, Ye, Xie, Rong‐Jun, and Lin, Qianqian

Subjects
*QUANTUM efficiency, *PHOTODETECTORS, *PHOTODIODES, *OPTOELECTRONIC devices, *COLOR vision, *ABSORPTION coefficients, *PHOTOVOLTAIC power generation
Abstract

Antimony sulfide (Sb2S3), a binary chalcogenide, has recently emerged as a promising candidate for photovoltaics due to its high absorption coefficient, facile processing, and lower toxicity. However, high‐performance photodiodes based on Sb2S3 have not been achieved and systematically investigated. Herein, Sb2S3‐based photodiodes based on conventional and inverted structures are developed, and their charge transport and spectral dependent quantum efficiency of these two types of devices are carefully modulated. After optimization, the conventional photodetectors achieve broadband responsivity up to 0.3 A W−1, high specific detectivity of 1.25 × 1012 Jones, and fast response speed of 6.4 µs with a small bias voltage of −0.5 V. On the other hand, the inverted devices exhibit imbalanced charge transport and color discrimination, which is promising for narrowband photodetection. These distinct device performances are highly dependent on the device architecture, which is crucial for designing efficient chalcogenide‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Published
2023
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86. Chalcogenide‐Based Narrowband Photodetectors for Imaging and Light Communication.

Author

Xu, Yalun, Li, Ruiming, Bai, Songxue, Li, Yanyan, Jia, Zhenglin, Yang, Yujie, Cui, Enkang, Yao, Fang, Wang, Du, Lei, Cheng, and Lin, Qianqian

Subjects
*OPTICAL communications, *PHOTODETECTORS, *CHARGE carriers, *PHOTOVOLTAIC power generation, *NEAR infrared radiation
Abstract

Chalcogenide‐based semiconductors have recently emerged as promising candidates for optoelectronic applications, mainly benefiting from their facile and low‐cost processability, chemical versatility, and tunable optoelectronic properties. Despite the recent success of chalcogenide‐based thin‐film photovoltaics, they have been barely leveraged in photodetection, mainly due to the complicated charge transport related to the trap states. In addition, most of the chalcogenide photodetectors are reported for broadband, visible photodetection, which is facile but lacks of impact for real applications. However, it is also possible to modulate the charge carrier dynamics of chalcogenide‐based materials, and devise novel devices, which can possess extra compelling features. These possibilities provide strong incentives for a detailed study on the chalcogenides‐based narrowband photodetectors, which are achieved by a filterless, charge collection narrowing strategy. The optimized narrowband photodetectors also exhibit extremely fast‐response (≈240 ns), relatively low dark current and noise, large linear dynamic range, and most importantly tunable spectral discrimination covering the whole range from UV to NIR. These devices also demonstrate great potential for imaging and communication. [ABSTRACT FROM AUTHOR]

Published
2023
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91. Design and locomotivity analysis of a novel deformable two-wheel-like mobile mechanism

Author

Li Ruiming, Li Yezhuo, Yan-An Yao, and Zhang Qianqian

Subjects
0209 industrial biotechnology, Bar (music), Computer science, Work (physics), Mode (statistics), 02 engineering and technology, Kinematics, Industrial and Manufacturing Engineering, Computer Science Applications, Mechanism (engineering), 020303 mechanical engineering & transports, 020901 industrial engineering & automation, 0203 mechanical engineering, Control and Systems Engineering, Control theory, Obstacle, Overconstrained mechanism, Torque
Abstract

Purpose The purpose of this paper is to propose a deformable two-wheel-like mobile mechanism based on overconstrained mechanism, with the abilities of fast rolling and obstacle surmounting. The drive torque of the multi-mode motions is generated by self-deformation. Moreover, the analyses of feasibility and locomotivity of two mobile modes are presented. Design/methodology/approach The main body of the two-wheel-like mobile mechanism is a kind of centrally driven 4 R linkages. The mobile mechanism can achieve the capabilities of fast rolling and obstacle surmounting through integrating two mobile modes (spherical-like rolling mode and polyhedral-like obstacle-surmounting mode) and can switch to the corresponding mode to move or surmount obstacles. The mobility and kinematics of the mobile modes are analyzed. Findings Based on the results of kinematics analysis and dynamics analysis of the wheel-like mechanism, the spherical-like rolling mode has the capability of fast rolling, and the polyhedral-like obstacle-surmounting mode has the capability of surmounting different obstacle heights by two submodes (quasi-static obstacle-surmounting submode and dynamic obstacle-surmounting submode). The proposed concept is verified by experiments on a physical prototype. Originality/value The work presented in this paper is a novel exploration to apply bar linkages in the field of scout. The two-wheel-like mobile mechanism improves the torque imbalance of bar linkages by centrally driven method, removes the rear support structures of the traditional two-wheeled mechanisms by self-deformation and increases the height of obstacle surmounting by mode switching angle.

Published
2020

100. Hybrid perovskite X-ray detectors with enhanced radioluminescence viathermally activated delayed fluorescence

Author

Xu, Yalun, Ying, Ao, Peng, Jiali, Yao, Fang, Li, Ruiming, Tan, Yao, Gong, Shaolong, and Lin, Qianqian

Abstract

Recently, metal halide perovskites have received great attention for detecting ionizing radiation. Perovskite-based photodetectors and scintillators have been successfully implemented for X-ray and γ-ray detection due to their high attenuation coefficient and excellent optoelectronic properties. However, relatively thick absorbing layers are required for the complete absorption of X-ray photons, which are very challenging to fabricate with solution processes. In this work, we designed hybrid devices coupled with excellent perovskite photodiodes to utilize the incident X-rays fully. Considering the heavy reabsorption of the perovskite layers, we blended CsPbBr3with a Cu(I)-containing thermally activated delayed fluorescent complex (MAC*)Cu(Cz) to achieve down-conversion luminescence effectively to maximize the radioluminescence quantum efficiency, and we also found a faster afterglow compared with the commercial scintillators. Furthermore, we systematically investigated the performance metrics of the CsPbIBr2photodiodes and scintillator films. The hybrid devices demonstrated significantly improved X-rays sensitivity, indicating potential for X-ray detection and imaging.

Published
2023
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