检索结果-内蒙古大学图书馆

Investigation on the stall types in impellers with different blade numbers

Journal of Hydrodynamics 2023年第2期35卷 299-313页

作者： Xiao-dong Liu Yao-jun Li Zhu-qing Liu Wei Yang College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing100083China

Stall is a complex flow phenomenon and its existence usually shows significant differences in different impeller *** this paper,the flow field characteristics and mechanism of stall types in impellers with different blade numbers were studied through the combination of experiment and numerical simulation at stall inception *** the experiments,it was observed that the five-blade impeller entered the rotating stall stage from a relatively stable flow field within a small flow rate *** the six-blade impeller,the root cause that stall vortices appeared in channels alternately rather than each one evenly was also reasonably *** validated numerical simulation method was utilized to reveal the three-dimensional flow field in impeller *** results indicate the swirling vortex near the impeller shroud was periodically sucked in and escaped from region near the blade suction side,which was the fundamental driving force of rotating *** sudden change of flow field caused by the fusion of the separation vortex at the channel inlet and the vortex induced by the swirling vortex near shroud is the essential reason for the formation of alternating ***’s more,the stall inception flow field is clearly defined in impellers,which is of great significance for the further analysis of stall *** on the distribution characteristics of vortex structure near impeller shroud with different blade numbers at different flow rate conditions,this paper deeply investigated the formation mechanism of different stall types in impellers.

关键词： Numerical simulation high-frequency particle image velocimetry(PIV) impellers swirling vortex stall type

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Improved Evolutionary Multitasking Optimization Algorithm With Similarity Evaluation of Search Behavior

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IEEE Transactions on Evolutionary Computation 2024年第3期29卷 1-1页

作者： Wu, Xiaolong Wang, Wei Zhang, Tengfei Han, Honggui Qiao, Junfei Beijing Key Laboratory of Computational Intelligence and Intelligent System Engineering Research Center of Digital Community Ministry of Education Beijing Artificial Intelligence Institute and Beijing Laboratory for Intelligent Environmental Protection Faculty of Information Technology Beijing University of Technology Beijing China

Task similarity is a major requisite to trigger knowledge sharing in evolutionary multitasking optimization (EMTO). Unfortunately, most of the existing EMTO algorithms only focus on the similarity between population distributions of tasks, but ignore the search behavior of populations, which may degrade the performance of cross-task knowledge sharing. Motivated by this, an improved EMTO algorithm with similarity evaluation of search behavior (SESB-IEMTO), employing the particle swarm optimization (PSO) algorithm as a task solver for each task, is proposed. It comprises three key elements: 1) a dynamic similarity-based evaluation strategy, 2) a cross-task knowledge adaptation method, and 3) a search direction sharing mechanism. Primarily, the source tasks with similar search behavior are discriminated with the dynamic similarity-based evaluation strategy, where individuals can be fully exploited for cross-task evolution. Then, the knowledge derived from these source tasks is regulated by the cross-task knowledge adaption method for alleviating the risk of negative transfer caused by the heterogeneity between tasks. Moreover, to further promote knowledge sharing between tasks, the search direction sharing mechanism is developed to navigate tasks efficiently searching for promising regions. Finally, the convergence of SESB-IEMTO is analyzed, and the effectiveness and superiority are also verified with the experiments on several benchmark tests and a real-world application study. IEEE

关键词： Multitasking

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Experimental investigations on characteristics of water-air two-phase flows during water-fillings in undulation pipelines

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Journal of Hydrodynamics 2024年第4期36卷 706-724页

作者： Xue-lin Tang Zong-ku Liu Ling Zhang Xiao-qin Li College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing100083China Mingyang Smart Energy Group Limited Zhongshan528400China

Visual and pressurized pipeline systems with single- and multi-undulation layouts were used to study experimentally and analyze theoretically the transient characteristics of water-air two-phase flow during water fillings in undulation pipelines based on the combination action analyses of both the communicating pipe and the gravity of the water-air two-phase flows in the descending pipe. For the single undulation pipeline, the complex two-phase flow-pattern evolutions including full pipe flow and stratified flow for low, medium, high water-filling velocity cases, respectively, lead to a great difference in transient pressure, flow pattern and the water-filling duration. Especially for low and medium water-filling velocity cases, the hydraulic theories related to hydraulic drop and hydraulic jump were employed to investigate the entrapped air pocket evolutions in the descending pipe, and the mechanism of negative pressure at the top of the undulation pipes was analyzed. For the same multi-undulation pipeline, due to the different elevations of the three undulation points along flow direction, namely three different types of pipeline layout, high-medium-low case (high elevation undulation point, medium one, and low one), low-medium-high and high-low-medium ones, their water-filling durations are significantly different, i.e., approximately 80.02 s, 227.34 s and 617.78 s. Meanwhile, there are significant differences in flow patterns in water filling, namely larger entrapped air pockets in three descending pipes for the high-medium-low case, entrapped air pockets in the first two descending pipes and open channel stratified flow in the last one for low-medium-high case, some bubbles in three descending pipes for the high-low-medium case.

关键词： Water-filling duration trapped air pockets water-air two-phase flow transient flow flow-pattern evolution multi-undulation pipelines

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Gait Learning Reproduction for Quadruped Robots Based on Experience Evolution Proximal Policy Optimization

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Journal of Shanghai Jiaotong University (Science) 2023年 1-9页

作者： Li, Chunyang Zhu, Xiaoqing Ruan, Xiaogang Liu, Xinyuan Zhang, Siyuan Faculty of Information Technology Beijing University of TechnologyBeijing Key Laboratory of Computational Intelligence and Intelligent SystemEngineering Research Center of Digital Community of Ministry of Education Beijing100124 China

Bionic gait learning of quadruped robots based on reinforcement learning has become a hot research topic. The proximal policy optimization (PPO) algorithm has a low probability of learning a successful gait from scratch due to problems such as reward sparsity. To solve the problem, we propose a experience evolution proximal policy optimization (EEPPO) algorithm which integrates PPO with priori knowledge highlighting by evolutionary strategy. We use the successful trained samples as priori knowledge to guide the learning direction in order to increase the success probability of the learning algorithm. To verify the effectiveness of the proposed EEPPO algorithm, we have conducted simulation experiments of the quadruped robot gait learning task on Pybullet. Experimental results show that the central pattern generator based radial basis function (CPG-RBF) network and the policy network are simultaneously updated to achieve the quadruped robot’s bionic diagonal trot gait learning task using key information such as the robot’s speed, posture and joints information. Experimental comparison results with the traditional soft actor-critic (SAC) algorithm validate the superiority of the proposed EEPPO algorithm, which can learn a more stable diagonal trot gait in flat terrain. © 2023, Shanghai Jiao Tong University.

关键词： Bionics

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3D reconstruction and defect pattern recognition of bonding wire based on stereo vision

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CAAI Transactions on Intelligence technology 2024年第2期9卷 348-364页

作者： Naigong Yu Hongzheng Li Qiao Xu Ouattara Sie Essaf Firdaous Faculty of Information Technology Beijing University of TechnologyBeijingChina Beijing Key Laboratory of Computing Intelligence and Intelligent System Beijing University of TechnologyBeijingChina Engineering Research Center of Digital Community Ministry of EducationBeijingChina College of Robotic UniversitéFélix Houphouët‐BoignyAbidjanCôte d’Ivoire

Non-destructive detection of wire bonding defects in integrated circuits(IC)is critical for ensuring product quality after ***-processing-based methods do not provide a detailed evaluation of the three-dimensional defects of the bonding ***,a method of 3D reconstruction and pattern recognition of wire defects based on stereo vision,which can achieve non-destructive detection of bonding wire defects is *** contour features of bonding wires and other electronic components in the depth image is analysed to complete the 3D reconstruction of the bonding *** to filter the noisy point cloud and obtain an accurate point cloud of the bonding wire surface,a point cloud segmentation method based on spatial surface feature detection(SFD)was *** can extract more distinct features from the bonding wire surface during the point cloud segmentation ***,in the defect detection process,a directional discretisation descriptor with multiple local normal vectors is designed for defect pattern recognition of bonding *** descriptor combines local and global features of wire and can describe the spatial variation trends and structural features of *** experimental results show that the method can complete the 3D reconstruction and defect pattern recognition of bonding wires,and the average accuracy of defect recognition is 96.47%,which meets the production requirements of bonding wire defect detection.

关键词： bonding wire defect detection point cloud point cloud segmentation

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Energy partition in laser-induced cavitation bubbles near the rigid wall with a gas-containing hole

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Journal of Hydrodynamics 2024年第3期36卷 435-443页

作者： Dong-qiao He Hai-gang Wen Si-yuan Geng Chen-xi Yang Qiang Zhong Zhi-feng Yao College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China PowerChina Beijing Engineering Corporation Limited Beijing100024China State Key Laboratory of Efficient Utilization of Agricultural Water Resources Beijing100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing100083China

To investigate the energy partition in laser-induced cavitation bubbles near the rigid wall with a gas-containing hole,we utilized a nanosecond resolution photography system based on a Q-switched Nd:YAG laser and conventional industrial camera to carefully observe the transient process of bubble collapse near the rigid wall with a gas-containing *** analyzed the generation of collapse microjets and the emission of collapse shock *** found that the cavitation bubble near the rigid wall with a gas-containing hole collapsed at different times and space,and produced various types of shock *** on the far field pressure information of the shock waves measured by hydrophone,the energy of the shock waves generated by the bubble collapse near the rigid wall with a gas-containing hole is calculated for the first *** results show that the ratio of collapse shock wave energy to bubble energy is approximately between 0.7 and 0.8.

关键词： Energy partition bubble collapse laser-induced shock wave gas-containing hole

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Transformer-based Siamese Neural Network Face Verification Method 8

Transformer-based Siamese Neural Network Face Verification M...

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8th International Conference on Intelligent Computing and Signal Processing, ICSP 2023

作者： Qiu, Shen Yang, HuaPeng Huang, ZhangQin Shen, DiYuan Beijing University of Technology Beijing Engineering Research Center for IoT Software and System Beijing China

ISBN: (纸本)9798350302455

Face verification, as a key part of person intelligence tracing, aims to determine whether the same person is in two face photos, which can be approximately transformed into a binary classification problem. In this paper, the siamese neural network architecture is adopted as the overall structure of the method, and the traditional bacbone network generally uses a convolutional neural network, this paper will use Vision Transformer as the backbone network as the method. Compared with convolutional neural network, its multi-headed attention mechanism can better focus on the larger sensory field and extract face features, which can then better perform face verification, while Binary cross-entropy is used as the loss function. After the validation of the private dataset, the model can recognize faces well and has excellent validation effect, which is of great value for the field of human intelligence tracing. © 2023 IEEE.

关键词： Convolutional neural networks

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Precise Processing of Satellite Space-time Data and Dynamic Warning Algorithm for Slope 8

Precise Processing of Satellite Space-time Data and Dynamic ...

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8th International Conference on Intelligent Computing and Signal Processing, ICSP 2023

作者： Li, Yao Huang, ZhangQin Gao, Han Huang, Ling Beijing University of Technology Beijing Engineering Research Center for IoT Software and System Beijing China

ISBN: (纸本)9798350302455

Deformation monitoring data can most intuitively reflect the current movement process of the landslide and is likewise the most essential and effective warning feature of the landslide warning model. To solve the current problem that it is difficult to identify the uniform deformation phase and adjust it dynamically in time, which leads to the high false alarm and leakage rate of the early warning algorithm, we adopt the Pauta criterion and the Lagrange interpolation method fused with the improved adaptive Kalman filter to improve the accuracy of the original monitoring data, propose a real-time determination method of uniform deformation phase based on statistical analysis, and construct a process-oriented dynamic early warning algorithm by examining the normal distribution of the second-order derivative values of the cumulative displacement curve and the changing trend of the linear regression coefficient of determination. The experimental results show that the research method can effectively reduce the abnormal fluctuation interference of data, accurately discriminate the uniform deformation phase, improve the early warning accuracy of the creep tangent angle warning model, and has excellent application value for the subsequent realization of systematic and automated real-time monitoring and warning. © 2023 IEEE.

关键词： Landslides

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Design of LoRa Communication Protocol for Image Transmission 8

Design of LoRa Communication Protocol for Image Transmission

引用

8th International Conference on Intelligent Computing and Signal Processing, ICSP 2023

作者： Gao, Han Huang, Zhangqin Zhang, Xiaobo Huang, Ling Beijing University of Technology Beijing Engineering Research Center for IoT Software and System Beijing China

ISBN: (纸本)9798350302455

With the expansion of IoT application scenarios, the demand for edge IoT devices with integrated video analysis capabilities is gradually increasing. In remote areas where cellular base stations cannot reach, a low-cost wireless communication self-organizing network is urgently needed to transmit video processing results and images. LoRa has strong anti-interference performance and relatively high transmission rate, which is suitable for completing delay-tolerant information transmission. However, the traditional LoRaWAN protocol has low efficiency in image transmission. This paper proposes a multi-packet transmission communication protocol based on LoRa, which reduces the time for traditional communication protocol confirmation and processing, and focuses more on the image transmission of LoRa. Experimental results show that the multi-packet transmission protocol achieves relatively high communication efficiency. © 2023 IEEE.

关键词： Image communication systems

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research on Multi-protocol Access Method for IoT Platform Based on Microservice Container Scheduling 8

Research on Multi-protocol Access Method for IoT Platform Ba...

引用

8th International Conference on Intelligent Computing and Signal Processing, ICSP 2023

作者： Fan, XiaoJie Huang, ZhangQin Huo, SiJia Zhang, XiaoBo Beijing University of Technology Beijing Engineering Research Center for IoT Software and System Beijing China

ISBN: (纸本)9798350302455

The number of Internet of Things (IoT) devices in the world has grown to 43 billion in 2023. With the expansion of the IoT industry, the types and communication protocols of IoT devices are also increasing. In the actual deployment of the Internet of Things, it is more complicated and difficult to develop a truly interconnected IoT platform in the face of a variety of IoT devices. At the same time, the increasing number of devices has brought great challenges to the high availability of the platform. We designed and implemented a multi-protocol access method for the IoT platform, which can configure public and private protocols according to requirements, and make up for the shortcomings of the current IoT platform in device access. In order to ensure the availability of the platform, the container dynamic scheduling method is generally adopted when the sudden high load demand is needed. However, due to the time-consuming operation in the container scaling process, the existing container scheduling method cannot immediately meet the load demand. We proposed a combined prediction model based on LSTM and RELM, and proposed a container dynamic scheduling strategy based on load prediction. This scheduling strategy is applied to the multi-protocol access method to ensure the stability and availability of the access process. Finally, the multi-protocol access method is tested. The results show that this method can ensure the access of multi-protocol IoT devices. The reliability test shows that it has good performance and meets the current demand for IoT platforms. In addition, the strategy of this paper is compared with other strategies to further verify the rationality and availability of the method. © 2023 IEEE.

关键词： Internet of things

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