|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Application of Computational Fluid Dynamics and Fluid Structure Interaction Techniques for Calculating the 3D Transient Flow of Journal Bearings Coupled with Rotor Systems显示文摘Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics (CFD)-fluid structure interaction (FSI) techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ''dynamic mesh'' technique. A new mesh movement approach is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the journal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function (UDF). The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system. | LI Qiang YU Guichang LIU Shulian ZHENG Shuiying | 2012 | Chinese Journal of Mechanical Engineering2012，25，5： | 19 |
| 2 | Photonic integrated spiking neuron chip based on a self-pulsating DFB laser with a saturable absorber显示文摘We proposed and experimentally demonstrated a simple and novel photonic spiking neuron based on a distributed feedback(DFB)laser chip with an intracavity saturable absorber(SA).The DFB laser with an intracavity SA(DFBSA)contains a gain region and an SA region.The gain region is designed and fabricated by the asymmetric equivalentπ-phase shift based on the reconstruction-equivalent-chirp technique.Under properly injected current in the gain region and reversely biased voltage in the SA region,periodic self-pulsation was experimentally observed due to the Q-switching effect.The self-pulsation frequency increases with the increase of the bias current and is within the range of several gigahertz.When the bias current is below the self-pulsation threshold,neuronlike spiking responses appear when external optical stimulus pulses are injected.Experimental results show that the spike threshold,temporal integration,and refractory period can all be observed in the fabricated DFB-SA chip.To numerically verify the experimental findings,a time-dependent coupled-wave equation model was developed,which described the physics processes inside the gain and SA regions.The numerical results agree well with the experimental measurements.We further experimentally demonstrated that the weighted sum output can readily be encoded into the self-pulsation frequency of the DFB-SA neuron.We also benchmarked the handwritten digit classification task with a simple single-layer fully connected neural network.By using the experimentally measured dependence of the self-pulsation frequency on the bias current in the gain region as an activation function,we can achieve a recognition accuracy of 92.2%,which bridges the gap between the continuous valued artificial neural networks and spike-based neuromorphic networks.To the best of our knowledge,this is the first experimental demonstration of a photonic integrated spiking neuron based on a DFB-SA,which shows great potential to realizing large-scale multiwavelength photonic spiking neural network chips. | YUECHUN SHI SHUIYING XIANG XINGXING GUO YAHUI ZHANG HONGJI WANG DIANZHUANG ZHENG YUNA ZHANG YANAN HAN YONG ZHAO XIAOJUN ZHU XIANGFEI CHEN XUN LI YUE HAO | 2023 | Photonics Research2023，11，8： | 2 |
| 3 | Experimental demonstration of coherent photonic neural computing based on a Fabry–Perot laser with a saturable absorber显示文摘As Moore’s law has reached its limits,it is becoming increasingly difficult for traditional computing architectures to meet the demands of continued growth in computing power.Photonic neural computing has become a promising approach to overcome the von Neuman bottleneck.However,while photonic neural networks are good at linear computing,it is difficult to achieve nonlinear computing.Here,we propose and experimentally demonstrate a coherent photonic spiking neural network consisting of Mach–Zehnder modulators(MZMs)as the synapse and an integrated quantum-well Fabry–Perot laser with a saturable absorber(FP-SA)as the photonic spiking neuron.Both linear computation and nonlinear computation are realized in the experiment.In such a coherent architecture,two presynaptic signals are modulated and weighted with two intensity modulation MZMs through the same optical carrier.The nonlinear neuron-like dynamics including temporal integration,threshold,and refractory period are successfully demonstrated.Besides,the effects of frequency detuning on the nonlinear neuron-like dynamics are also explored,and the frequency detuning condition is revealed.The proposed hardware architecture plays a foundational role in constructing a large-scale coherent photonic spiking neural network. | DIANZHUANG ZHENG SHUIYING XIANG XINGXING GUO YAHUI ZHANG BILING GU HONGJI WANG ZHENZHEN XU XIAOJUN ZHU YUECHUN SHI YUE HAO | 2023 | Photonics Research2023，11，1： | 2 |
| 4 | Control System of Linear Compressor Based on Bidirectional Triode Thyristor 显示文摘 | Zhao Peng Li Zhihai Zheng Shuiying | 2011 | Measuring Technology and Mechatronics Automation2011，，： | 1 |
| 5 | Photonic integrated neuro-synaptic core for convolutional spiking neural network显示文摘Neuromorphic photonic computing has emerged as a competitive computing paradigm to overcome the bottlenecks of the von-Neumann architecture.Linear weighting and nonlinear spike activation are two fundamental functions of a photonic spiking neural network(PSNN).However,they are separately implemented with different photonic materials and devices,hindering the large-scale integration of PSNN.Here,we propose,fabricate and experimentally demonstrate a photonic neuro-synaptic chip enabling the simultaneous implementation of linear weighting and nonlinear spike activation based on a distributed feedback(DFB)laser with a saturable absorber(DFB-SA).A prototypical system is experimentally constructed to demonstrate the parallel weighted function and nonlinear spike activation.Furthermore,a fourchannel DFB-SA laser array is fabricated for realizing matrix convolution of a spiking convolutional neural network,achieving a recognition accuracy of 87%for the MNIST dataset.The fabricated neuro-synaptic chip offers a fundamental building block to construct the large-scale integrated PSNN chip. | Shuiying Xiang Yuechun Shi Yahui Zhang Xingxing Guo Ling Zheng Yanan Han Yuna Zhang Ziwei Song Dianzhuang Zheng Tao Zhang Hailing Wang Xiaojun Zhu Xiangfei Chen Min Qiu Yichen Shen Wanhua Zheng Yue Hao | 2023 | Opto-Electronic Advances2023，6，11： | 1 |
| 6 | Nonlinear neural computation in an integrated FP-SA spiking neuron subject to incoherent dual-wavelength optical pulse injections显示文摘Photonic nonlinear computation is the critical cornerstone of photonic neuromorphic computing.As one of the key information function units in the photonic spiking neural networks,the photonic spiking neurons are responsible for the nonlinear computation of the network.Recently,the neuron-like nonlinear computation of the photonic spiking neuron has attracted considerable attention. | Ziwei SONG Shuiying XIANG Xingxing GUO Shuang GAO Biling GU Dianzhuang ZHENG Xiangfei CHEN Yuechun SHI | 2023 | Science China(Information Sciences)2023，66，12： | 0 |
| 7 | Resistance Torque Based Variable Duty-Cycle Control Method for a Stage Ⅱ Compressor显示文摘The resistance torque of a piston stage Ⅱ compressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the strenuous fluctuations in the piston stage Ⅱ compressor, a variable duty-cycle control method based on the resistance torque is proposed. A dynamic model of a stage Ⅱ compressor is set up, and the resistance torque and other characteristic parameters are acquired as the control targets. Then, a variable duty-cycle control method is applied to track the resistance torque, thereby improving the working performance of the compressor. Simulated results show that the compressor, driven by the proposed method,requires lower current, while the rotating speed and the output torque remain comparable to the traditional variable-frequency control methods. A variable duty-cycle control system is developed, and the experimental results prove that the proposed method can help reduce the specific power, input power, and working noise of the compressor to 0.97 k W·m^(-3)·min^(-1), 0.09 k W and 3.10 d B,respectively, under the same conditions of discharge pressure of 2.00 MPa and a discharge volume of 0.095 m^3/min. The proposed variable duty-cycle control method tracks the resistance torque dynamically, and improves the working performance of a Stage Ⅱ Compressor. The proposed variable duty-cycle control method can be applied to other compressors, and can provide theoretical guidance for the compressor. | Meipeng ZHONG Shuiying ZHENG | 2017 | Chinese Journal of Mechanical Engineering2017，30，4： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员