15 results on '"Wu, Ruihuan"'
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2. True random bit generator based on optoelectronic oscillator with randomly distributed feedback.
- Author
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Wu, Ruihuan, Wang, Ziyang, Wang, Zhengkang, Li, Bo, and Liu, Hongzhan
- Subjects
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FIBER Bragg gratings - Abstract
A true random bit generator (T-RBG) based on optoelectronic oscillator (OEO) with randomly distributed feedback is proposed and experimentally demonstrated. Through the implementation of a random fiber Bragg grating (RFBG) inside the OEO loop, a randomly distributed feedback is introduced into the proposed scheme, which allows it to produce broadband random signal and be used as entropy source. The random sequence can be obtained at a rate of 250 Gbps (50 GS/s × 5 bits) in real time, and it successfully passed all the NIST SP 800-22 tests. • A true random bit generator based on optoelectronic oscillator with randomly distributed feedback is proposed to generate true random bit sequences. • A random fiber Bragg grating is inserted into the OEO cavity to enable the proposed system to generate broadband random signal. • Random sequences can be obtained at a rate of 250 Gbps (50 GS/s × 5 bits) in real time and pass all the NIST SP 800-22 statistical tests. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
3. Residual Parallel Neural Networks Aided Inverse Design for Multifunctional Reconfigurable Metamaterial Perfect Absorbers.
- Author
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Wang, Shuqin, Wei, Zhongchao, Wu, Ruihuan, Ma, Qiongxiong, Ding, Wen, and Guo, Jianping
- Subjects
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METAMATERIALS , *DEEP learning , *ENERGY harvesting , *LIQUID crystals , *ABSORPTION spectra - Abstract
In recent years, significant strides have been made in the inverse design of metamaterial perfect absorbers (MPAs) using deep learning techniques. However, this progress has been hindered by the functional homogeneity arising from the structural uniformity of the inverse-designed MPAs. In this paper, we address this limitation by designing reconfigurable MPAs (RMPAs) with three distinct structures and propose a residual parallel neural network (RPNN) that incorporates the optimized residual fully connected neural network (RFC-NN) for the inverse design of multifunctional MPAs. The trained RPNN accurately predicts the structural parameters and their corresponding absorption spectra with remarkable precision, yielding R2 values of 0.9981 and 0.9928, respectively. With this model, we successfully inverted the design of MPAs with three functions: broadband absorption, dual-band absorption, and triple-band absorption properties. A particularly noteworthy achievement was the realization of absorption bandwidth shifts using liquid crystal (LC) materials. Our RPNN showcases its proficiency in designing RMPAs with multifunctionality, all within a single network model. This marks a significant advancement over previous research methodologies. The proposed methodology holds great promise in diverse applications such as solar energy harvesting, detection, and filtration. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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4. Correlation optical time domain reflectometry based on broadband random optoelectronic oscillator.
- Author
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Li, Bo, Wu, Ruihuan, Hong, Weiyi, and Liu, Hongzhan
- Subjects
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REFLECTOMETRY , *FIBER Bragg gratings , *OPTOELECTRONIC devices , *SEMICONDUCTOR lasers , *QUANTUM cascade lasers , *SPATIAL resolution - Abstract
A correlation optical time domain reflectometry (COTDR) based on broadband random optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. Different from the conventional COTDR that utilizes an external feedback semiconductor laser as the chaotic source, the proposed scheme employs a random optoelectronic oscillator as the random signal source. With the assistance of randomly distributed feedback in the OEO caused by the random fiber Bragg grating, the generated signals have random and broadband characteristics, whose frequencies are not restricted by a fixed cavity length in the OEO. Due to the avoidance of relaxation oscillations in semiconductor chaotic laser, the generated random signal has a wide and flat spectrum as well as excellent autocorrelation features. The experimental results illustrate that the proposed COTDR can achieve a range-independent spatial resolution of about 10 mm and its dynamic range is at least 78.47 km. • A correlation optical time domain reflectometry based on broadband random optoelectronic oscillator is proposed and experimentally demonstrated. • A random optoelectronic oscillator is employed as the random signal source with a wide and flat spectrum alongside excellent autocorrelation features. • The proposed COTDR can achieve a range-independent spatial resolution of about 10 mm and its dynamic range is at least 78.47 km. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. High power flatness and wide spectrum range microwave frequency combs generation based on an actively mode-locked optoelectronic oscillator with intensity feed-forward path.
- Author
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Wang, Ziyang, Wu, Ruihuan, Li, Bo, Guo, Jianping, and Liu, Hongzhan
- Subjects
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MICROWAVES , *PHASE noise , *POWER spectra , *CIRCADIAN rhythms - Abstract
• An actively mode-locked OEO with intensity feed-forward path is proposed to generate MFCs with high power flatness and wide spectrum range. • An intensity feed-forward path with the same delay as the main loop is introduced to realize signal power equalization. • Comb lines within ± 10 dB power variations increase from 15 to 78 and power difference decreases from 8.2 dB to 1.5 dB due to the use of intensity feed-forward technology. An actively mode-locked optoelectronic oscillator (OEO) with intensity feed-forward path is proposed and experimentally demonstrated to generate microwave frequency combs (MFCs) with high power flatness and wide spectrum range. An intensity feed-forward path with the same time delay as the delay of the main loop is inserted into an actively mode-locked OEO, which optimizes the power flatness and spectrum range of the generated MFCs signal. Experimental results show that comb lines within ± 10 dB power variations increase from 15 to 78 and power difference decreases from 8.2 dB to 1.5 dB when the intensity feed-forward path is working in the loop. Moreover, the performance of single sideband (SSB) phase noise with different lengths of SMF inserted in the proposed scheme are also investigated. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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6. Improvement of linearity in intensity-modulated analog photonic link based on all-optical wave shaping.
- Author
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Lei, Ruichen, Wu, Ruihuan, and Liu, Hongzhan
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INTERMODULATION distortion , *COMPUTER simulation - Abstract
In this paper, a novel all-optical architecture for multi-order nonlinear distortions (NDs) suppression in the intensity-modulation direct-detection (IM-DD) analog photonic link (APL) is proposed. A systematic analysis of the relationship between the NDs and all optical sidebands (OSBs) is summarized. Numerical simulation results show that, by optimizing the amplitude and phase of OSB, the 3rd-order intermodulation distortion (IMD3) can be significantly suppressed. Consequently, the spurious-free dynamic range (SFDR) of 107.1 dB Hz 8 / 9 is obtained, which is improved by 16.17 dB compared with a single quadrature biased Mach–Zehnder modulator (MZM) used in APL. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. Transfer‐Learning‐Enabled 3D reconfigurable broadband solar metamaterial absorbers design.
- Author
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Wang, Shuqin, Ma, Qiongxiong, Wu, Ruihuan, Ding, Wen, and Guo, Jianping
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ARTIFICIAL neural networks , *METAMATERIALS , *DEEP learning , *AIR conditioning , *AIR masses , *ENERGY harvesting , *SOLAR energy - Abstract
Research on metamaterials shows excellent potential in the field of solar energy harvesting. In recent years, the design of broadband solar metamaterial absorbers (SMAs) has attracted significant interest with the wide application of deep learning methods. This paper proposes a deep neural network (DNN) to realize forward prediction and inverse design of reconfigurable 3D SMAs. In the inverse design, a polarization-insensitive broadband SMA with an absorption bandwidth of 2.7 μm and an average absorption rate of 97.6% with an adjustable bandwidth range of 369 nm is successfully designed. The design of SMAs with different structures is also realized by a transfer learning method to improve the training speed and performance further. Using the transfer learning approach, the training speed of the neural network target model can be accelerated, and its training performance can be improved on small datasets by utilizing the trained neural network source model. Meanwhile, using the trained inverse design target model, a polarization-insensitive broadband SMA was designed with an absorption bandwidth of 2.7 μm, an average absorption of 97.9%, and an adjustable bandwidth range of 141 nm. Finally, we verified the solar energy harvesting capability of the designed broadband SMAs under real-world conditions using air mass (AM) 1.5, and they were calculated to be capable of harvesting the vast majority of the energy. The method is instructive in the design process of SMAs and can be effectively used to explore multifunctional complex nanophotonic devices. • Designing reconfigurable solar absorbers with material selectivity using deep learning methods. • Design of ultra-wideband solar metmaterial absorbers with different shapes through the transfer learning approach. • The designed solar metamaterial absorber has high solar energy harvesting performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Visual Detection of Road Cracks for Autonomous Vehicles Based on Deep Learning.
- Author
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Meftah, Ibrahim, Hu, Junping, Asham, Mohammed A., Meftah, Asma, Zhen, Li, and Wu, Ruihuan
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AUTONOMOUS vehicles , *DEEP learning , *CONVOLUTIONAL neural networks , *CONCRETE pavements , *RANDOM forest algorithms , *MACHINE learning - Abstract
Detecting road cracks is essential for inspecting and assessing the integrity of concrete pavement structures. Traditional image-based methods often require complex preprocessing to extract crack features, making them challenging when dealing with noisy concrete surfaces in diverse real-world scenarios, such as autonomous vehicle road detection. This study introduces an image-based crack detection approach that combines a Random Forest machine learning classifier with a deep convolutional neural network (CNN) to address these challenges. Three state-of-the-art models, namely MobileNet, InceptionV3, and Xception, were employed and trained using a dataset of 30,000 images to build an effective CNN. A systematic comparison of validation accuracy across various base learning rates identified a base learning rate of 0.001 as optimal, achieving a maximum validation accuracy of 99.97%. This optimal learning rate was then applied in the subsequent testing phase. The robustness and flexibility of the trained models were evaluated using 6,000 test photos, each with a resolution of 224 × 224 pixels, which were not part of the training or validation sets. The outstanding results, boasting a remarkable 99.95% accuracy, 99.95% precision, 99.94% recall, and a matching 99.94% F1 Score, unequivocally affirm the efficacy of the proposed technique in precisely identifying road fractures in photographs taken on real concrete surfaces. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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9. Some generalizations of the new SOR-like method for solving symmetric saddle-point problems.
- Author
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Wen, Ruiping, Wu, Ruihuan, and Guan, Jinrui
- Subjects
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GENERALIZATION , *SADDLEPOINT approximations , *SCIENTIFIC computing , *NUMERICAL analysis , *STOCHASTIC convergence - Abstract
Saddle-point problems arise in many areas of scientific computing and engineering applications. Research on the efficient numerical methods of these problems has become a hot topic in recent years. In this paper, we propose some generalizations of the new SOR-like method based on the original method. Convergence of these methods is discussed under suitable restrictions on iteration parameters. Numerical experiments are given to show that these methods are effective and efficient. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
10. Dynamics of Electron Pearcey– Gaussian Beams in a Constant Magnetic Field.
- Author
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He, Xingyi, Huang, Haoyu, Xu, Chuangjie, Deng, Xiaofang, Wu, You, Tang, Huilin, Xu, Danlin, Luo, Shengbao, Liu, Jiatian, Wu, Ruihuan, and Deng, Dongmei
- Subjects
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GAUSSIAN beams , *MAGNETIC fields , *MAGNETIC field effects , *GAUSSIAN function , *ELECTRON beams - Abstract
A new kind of electron Pearcey‐Gaussian beam (EPGB) with auto‐focusing properties in the presence of an additional magnetic field is introduced, which is composed of the multiplication of the Pearcey function and the Gaussian function. The closed‐form expressions of the EPGBs are obtained. Based on different initial transverse velocities, different dynamics of the EPGBs are presented. The effect of the magnetic field toward the maximum focusing plane is also demonstrated. The analytical results are in excellent agreement with direct numerical simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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11. Performance analysis of FSO/THz-RF dual-hop link based on NOMA.
- Author
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Liu, Rongpeng, Yuan, Jia, Wang, Ziyang, Wang, Xuerui, Li, Bo, Lu, Jingwei, Wang, Yawei, Wu, Ruihuan, Wei, Zhongchao, and Liu, Hongzhan
- Subjects
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LINEAR orderings , *RADIO frequency - Abstract
To compensate for the deficiencies of low spectrum efficiency (SE) and scarce spectrum resources in Radio Frequency (RF), the FSO/THz-RF dual-hop downlink based on Non-Orthogonal Multiple Access (NOMA) is proposed, which utilizes the superior SE of NOMA and the spectrum resources of Free-Space Optical (FSO) and Terahertz (THz). Closed-form expressions of outage probability (OP) and ergodic capacity (EC) are derived for single-user and NOMA system, accounting for joint effects of channel fading, pointing error, and path loss. Additionally, corresponding asymptotic OP and diversity gains provide valuable physical insights. Results show that asymptotic OP and diversity gains are equal for both single-user and NOMA system, with diversity gains dependent on the performance parameters of the first link, independent of the total number and order of users. Moreover, better system performance is achieved with a smaller power allocation coefficient (PAC) mean deviation and NOMA system integer coefficient (NSIC). Finally, numerical results illustrate the superiority of the system. [Display omitted] • NOMA FSO/THz-RF links are modeled to improve SE and to economize spectrum resources. • The OP, AOP and EC are calculated and the coding gain and diversity gain are derived. • An algorithm to determine the optimal PAC and NSIC and two lower bounds are studied. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Realizing Multi-Absorption Properties Metamaterial Absorbers by a Dual-Channel Tandem Neural Network.
- Author
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Wang, Shuqin, Ma, Qiongxiong, Wei, Zhongchao, Liu, Wanrong, Wu, Ruihuan, Ding, Wen, and Guo, Jianping
- Abstract
Deep learning-based research on metamaterial absorbers (MAs) has received increasing attention. However, the problem of homogeneity of structure and material of MAs has constrained their further development. In this paper, we designed MA with a top metal layer consisting of eight rectangular nano-rods, and adjusting their lengths can form various structures. In addition, we formed a material database for constructing MAs with the results of random combinations of eight materials and represented them in a coded manner. Meanwhile, we design MAs with ultra-wideband and dual absorption bandwidths using a dual-channel tandem neural network (DTNN). Compared with the existing methods, our method not only simplifies the steps of selecting materials and structures but also enables the design of MAs with different absorption properties. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. Nonlinear dynamics of the dual-loop optoelectronic oscillator based on polarization multiplexing.
- Author
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Zhang, Xiaohao, Li, Zhaozhao, Li, Bo, Wu, Ruihuan, and Hong, Weiyi
- Subjects
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NONLINEAR oscillators , *NUMERICAL analysis , *MULTIPLEXING , *DYNAMICAL systems , *SYSTEM dynamics , *MICROWAVES , *PSYCHOLOGICAL feedback - Abstract
This paper focuses on the temporal dynamics of the dual-loop optoelectronic oscillator (OEO) based on polarization multiplexing. The delay-differential equation (DDE) for the dual-loop OEO system is presented for the first time. After employing microwave envelope method to simplify the DDE, the envelope signal equation describing the system dynamics is obtained. Stability analysis of the static solution of the envelope signal equation is also performed, and the gain thresholds for the system to exhibit various dynamic behaviours are calculated. Moreover, the proposed nonlinear dynamics approach reveals the stability of microwave envelope in detail as a function of the feedback gain and coupling coefficient, which indicates that there is not monotonously incremental relationship between envelope amplitude of the ultrapure microwave and the feedback gain. Finally, the experimental measurements confirm the results obtained from the theoretical and numerical analysis. • We develop a first-order envelope signal equation to descript the carrier-wave dynamics of a dual-loop OEO system. • We obtian the conditions for the occurrence of various dynamical behaviors of the system. • The experimental measurements confirm the results obtained from the theoretical and numerical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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14. Efficient identification of orbital angular momentum modes carried by Bessel Gaussian beams in oceanic turbulence channels using convolutional neural network.
- Author
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Liu, Wenyi, Jin, Meng, Hao, Yuan, Deng, Dongmei, Wu, Ruihuan, Wei, Zhongchao, and Liu, Hongzhan
- Subjects
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CONVOLUTIONAL neural networks , *GAUSSIAN beams , *ANGULAR momentum (Mechanics) , *BESSEL beams , *TURBULENCE , *HARTREE-Fock approximation - Abstract
As one of the spatial dimensions, orbital angular momentum (OAM) expands the channel capacity of underwater wireless optical communication (UWOC) system. However, the performance of the OAM-UWOC system is degraded due to the distortion of the OAM by oceanic turbulence. In this paper, we present a 7-layer convolutional neural network (CNN) and validate its ability to identify OAM patterns carried by Bessel Gaussian (BG) beams in oceanic turbulence channels. The trained CNN performs the task of recognizing OAM patterns with an accuracy of over 99% under weak-to-moderate oceanic turbulence at 100 m. Furthermore, in order to demonstrate the performance and robustness of the designed CNN, the effects of training sample number, epoch, turbulence intensity, balance parameter, transmission distance, type of training dataset, and coding method on the recognition ability of CNN are fully investigated. We hope that the method devised in our work will contribute to UWOC and facilitate its further development. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
15. A possible mechanism of the Scandinavian ozone loss.
- Author
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Zou Han, Zhou Libo, Ji Chongping, Wang Wei, Jian Yongxiao, and Wu Ruihuan
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OZONE layer depletion , *DIVERGENCE (Meteorology) - Abstract
Examines the possible mechanism of the Scandinavian ozone loss. Role of ozone divergence near isoentropic surface in ozone loss; Difference between the zonal average and the area-weighted average in corresponding regions; Evidence of maximum surplus in summer.
- Published
- 2001
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