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HVAC energy consumption prediction based on RJITL deep neural network model

Journal of Intelligent and Fuzzy systems 2024年第4期46卷 9029-9042页

作者： Li, Xiaoli Du, Linhui Yu, Xiaowei Wang, Kang Hu, Yongkang Faculty of Information Technology Beijing University of Technology Beijing China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing Advanced Innovation Center for Future Internet Technology Beijing University of Technology Beijing China Engineering Research Center of Digital Community Ministry of Education Beijing University of Technology Beijing China Instrumentation Technology Economy Institute Beijing China

During the operation of HVAC (Heating, Ventilation, and Air-Conditioning) systems, precise energy consumption prediction plays an important role in achieving energy savings and optimizing system performance. However, the HVAC system is a complex and dynamic system characterized by a large number of variables that exhibit significant changes over time. Therefore, it is inadequate to rely on a fixed offline model to adapt to the dynamic changes in the system that consume tremendous computation time. To solve this problem, a deep neural network (DNN) model based on Just-in-Time learning with hyperparameter R (RJITL) is proposed in this paper to predict HVAC energy consumption. Firstly, relevant samples are selected using Euclidean distance weighted by Spearman coefficients. Subsequently, local models are constructed using deep neural networks supplemented with optimization techniques to enable real-Time rolling energy consumption prediction. Then, the ensemble JITL model mitigates the influence of local features, and improves prediction accuracy. Finally, the local models can be adaptively updated to reduce the training time of the overall model by defining the update rule (hyperparameter R) for the JITL model. Experimental results on energy consumption prediction for the HVAC system show that the proposed DNN-RJITL method achieves an average improvement of 5.17% in accuracy and 41.72% in speed compared to traditional methods. © 2024-IOS Press. All rights reserved.

关键词： Energy utilization

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Investigations of the dynamical behaviors of a millimeter-scale cavitation bubble near the rigid wall

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Journal of Hydrodynamics 2023年第6期35卷 1064-1076页

作者： Dan Zi Dong-qiao He Zhi-feng Yao Fu-jun Wang Qiang Zhong Pin Lyu 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 Beijing100083China Yichang Testing Technology Research Institute Yichang443000China

The collapse of the cavitation bubble near the rigid wall emits shock waves and creates micro-jet,causing cavitation damage and operation instability of the hydraulic *** this paper,the millimeter-scale bubble near the rigid wall was investigated experimentally and numerically with the help of a laser photogrammetry system with nanosecond-micron space-time resolution and the open source package *** morphological characteristics of the bubble during its growth phase,collapse phase and rebound phase were observed by experiment and numerical simulation,and characteristics of the accompanying phenomena including the shock wave propagation and micro-jet evolution were well *** numerical results agree well with the experimental *** bubble starts from a tiny small size with high internal pressure and expands into a sphere with a radius of 1.07 mm forγ=d/R_(max)=*** bubble collapses into a heart shape and moves towards to the rigid wall during its collapse phase,resulting in a higher pressure load for the rigid wall in the second *** maximum pressure of the shock wave of the first bubble collapse phase reaches 5.4 MPa,and the velocity of the micro-jet reaches approximately 100 m/*** study enriches the existing experimental and numerical results of the dynamics of the near-wall cavitation bubble.

关键词： Cavitation bubble collapse shock wave micro jet the rigid wall

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XGCN:a library for large-scale graph neural network recommendations

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Frontiers of Computer Science 2024年第3期18卷 247-249页

作者： Xiran SONG Hong HUANG Jianxun LIAN Hai JIN National Engineering Research Center for Big Data Technology and System Services Computing Technology and System LabCluster and Grid Computing LabSchool of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhan 430074China Microsoft Research Asia Beijing 100080China

1 Introduction Graph Neural Networks(GNNs)have gained widespread adoption in recommendation systems,and nowadays there is a pressing need to effectively manage large-scale graph data[1].When it comes to large graphs,GNNs may encounter the scalability issue stemming from their multi-layer messagepassing ***,scaling GNNs has emerged as a crucial research area in recent years,with numerous scaling strategies being proposed.

关键词： scaling gained operations

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Transfer Learning in Motor Imagery Brain Computer Interface: A Review

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Journal of Shanghai Jiaotong university(Science) 2024年第1期29卷 37-59页

作者：李明爱许冬芹 Faculty of Information Technology Beijing University of TechnologyBeijing 100124China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing 100124China Engineering Research Center of Digital Community Ministry of EducationBeijing 100124China

Transfer learning,as a new machine learning methodology,may solve problems in related but different domains by using existing knowledge,and it is often applied to transfer training data from another domain for model training in the case of insuficient training *** recent years,an increasing number of researchers who engage in brain-computer interface(BCI),have focused on using transfer learning to make most of the available electroencephalogram data from different subjects,effectively reducing the cost of expensive data acquisition and labeling as well as greatly improving the learning performance of the *** paper surveys the development of transfer learning and reviews the transfer learning approaches in *** addition,according to the"what to transfer"question in transfer learning,this review is organized into three contexts:instance-based transfer learning,parameter-based transfer learning,and feature-based transfer ***,the current transfer learning applications in BCI research are summarized in terms of the transfer learning methods,datasets,evaluation performance,*** the end of the paper,the questions to be solved in future research are put forward,laying the foundation for the popularization and in-depth research of transfer learning in BCI.

关键词： transfer learning brain-computer interface(BCI) electroencephalogram machine learning

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Investigation of cavitation erosion caused by laser-induced single bubble collapse near alloy coating surface

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Journal of Hydrodynamics 2023年第5期35卷 876-886页

作者： Hai-gang Wen Zhi-feng Yao Qin Wu Yu-rong Sun Chen-xi Yang Qiang Zhong 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 School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China

To investigate the mechanism of cavitation erosion caused by laser-induced single bubble near the surface coating alloy coating material, 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 under different conditions. We analyzed the generation of collapse microjets and the emission of collapse shock waves and explored the cavitation erosion characteristics caused by laser-induced single bubble collapse. We discovered that even on surfaces of highly hard and corrosion-resistant alloy coatings, severe cavitation erosion occurred, and there was a phenomenon of mismatch between the cavitation erosion location and the bubble projection position. The intensity of cavitation erosion depended on the energy self-focusing effect of the collapse shockwaves. In the experiments, we also observed the self-focusing phenomenon of collapse shockwaves under different conditions. The self-focusing effect of collapse shockwaves weakened as the distance between the bubble and the material surface increased, which may be the cause of cavitation erosion induced by a laser-induced single bubble.

关键词： Cavitation erosion bubble collapse laser-induced shock wave self-focusing effect

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Investigation on method of characteristics and semi-implicit method for pressure linked equations algorithms for water hammer based on unsteady friction

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Journal of Hydrodynamics 2024年第6期36卷 1155-1166页

作者： Zong-ku Liu Guo-hong Wu Hao Wang Jia-xiang Zhang Xue-lin Tang 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 State Key Laboratory of Hydroscience and Engineering and Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China

The misoperation of hydraulic components such as pumps and valves in pressurized pipelines triggers water hammer phenomena and seriously threats the safe operation of hydraulic *** present,the main water hammer simulation methods are method of characteristics(MOC),and further investigation of new algorithms is ***,a new method for simulating the water hammer using the finite volume method(FVM),semi-implicit method for pressure linked equations(SIMPLE)algorithm is proposed in the present *** with the experimental data,the accuracy and reliability of the proposed algorithm are *** show that the IAB,MIAB friction models not only predict the first pressure peak but also accurately predict the pressure *** the comparison of the MOC,SIMPLE algorithms,the results of the two algorithms are almost the same in front of the valve,while near the upstream tank,when using the same friction model,the pressure attenuation predicted by the SIMPLE algorithm is slightly greater than that of the MOC method and closer to the experimental ***,the newly proposed algorithm can serve as an alternative to the MOC method in simulating water *** investigation enriches the numerical methods of hydraulic transients and lays the foundation for subsequent program development.

关键词： Hydraulic transient semi-implicit method for pressure linked equations(SIMPLE)algorithm Navier-Stokes equations finite volume method(FVM)

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A fast calculation method for three-impulse contingency return trajectory during the near-moon phase based on differential algebra

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Chinese Journal of Aeronautics 2025年第4期38卷 286-304页

作者： Lin LU Haiyang LI Tianshan DONG Wanmeng ZHOU College of Aerospace Science and Technology National University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China Beijing Institute of Spacecraft System Engineering Beijing 100094China China Astronaut Research and Training Center Beijing 100094China

Aimed at the demand of contingency return at any time during the near-moon phase in the manned lunar landing missions,a fast calculation method for three-impulse contingency return trajectories is ***,a three-impulse contingency return trajectory scheme is presented by combining the Lambert transfer and maneuver at the special ***,a calculation model of three-impulse contingency return trajectories is ***,fast calculation methods are proposed by adopting the high-order Taylor expansion of differential algebra in the twobody trajectory dynamics model and perturbed trajectory dynamics ***,the performance of the proposed methods is verified by numerical *** results indicate that the fast calculation method of two-body trajectory has higher calculation efficiency compared to the semi-analytical calculation method under a certain accuracy *** to its high efficiency,the characteristics of the three-impulse contingency return trajectories under different contingency scenarios are further analyzed *** findings can be used for the design of contingency return trajectories in future manned lunar landing missions.

关键词： Manned lunar landing Contingency return trajectory Trajectory calculation method Differential algebra Trajectory characteristic analysis

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Vibration-Based Fault Diagnosis for Railway Point Machines Using VMD and Multiscale Fluctuation-Based Dispersion Entropy

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Chinese Journal of Electronics 2024年第3期33卷 803-813页

作者： Yongkui SUN Yuan CAO Peng LI Guo XIE Tao WEN Shuai SU National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University School of Electronic and Information Engineering Beijing Jiaotong University Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xi'an University of Technology Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University

As one of the most important railway signaling equipment,railway point machines undertake the major task of ensuring train operation *** fault diagnosis for railway point machines becomes a hot *** the advantage of the anti-interference characteristics of vibration signals,this paper proposes an novel intelligent fault diagnosis method for railway point machines based on vibration signals.A feature extraction method combining variational mode decomposition(VMD) and multiscale fluctuation-based dispersion entropy is developed,which is verified a more effective tool for feature ***,a two-stage feature selection method based on Fisher discrimination and ReliefF is proposed,which is validated more powerful than single feature selection ***,support vector machine is utilized for fault *** comparisons show that the proposed method performs *** diagnosis accuracies of normal-reverse and reverse-normal switching processes reach 100% and 96.57% ***,it is a try to use new means for fault diagnosis on railway point machines,which can also provide references for similar fields.

关键词： Fault diagnosis Railway point machine Vibration signal Variational mode decomposition Two-stage feature selection

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Investigation on the stall types in impellers with different blade numbers

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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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