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Differential pressure reset strategy based on reinforcement learning for chilled water systems

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Building Simulation 2022年第2期15卷 233-248页

作者： Xinfang Zhang Zhenhai li zhengwei li Shunian Qiu Hai Wang School of Mechanical Engineering Tongji UniversityShanghaiChina Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghaiChina

Air conditioning water systems account for a large proportion of building energy *** a pressure-controlled water system,one of the key measures to save energy is to adjust the differential pressure setpoints during ***,such adjustments are based either on certain rules,which rely on operator experience,or on complicated models that are not easy to *** this paper,a data-driven control method based on reinforcement learning is *** main idea is to construct an agent model that adapts to the researched *** of directly being told how to react,the agent must rely on its own experiences to *** with traditional control strategies,reinforcement learning control(RLC)exhibits more accurate and steady performances while maintaining indoor air temperature within a limited range.A case study shows that the RLC strategy is able to save substantial amounts of energy.

关键词： water system differential pressure reset reinforcement learning control energy saving

Model free optimization of building cooling water systems with refined action space

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Building Simulation 2023年第4期16卷 615-627页

作者： Qiaofeng Xiong zhengwei li Wenxia Cai Zhechao Wang School of Mechanical Engineering Tongji University ShanghaiChina Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghaiChina

Deep Q Network(DQN)is an efficient model-free optimization method,and has the potential to be used in building cooling water ***,due to the high dimension of actions,this method requires a complex neural ***,both the required number of training samples and the length of convergence period are barriers for real ***,penalty function based exploration may lead to unsafe actions,causing the application of this optimization method even more *** solve these problems,an approach to limit the action space within a safe area is proposed in this *** of all,the action space for cooling towers and pumps are separated into two ***,for each type of equipment,the action space is further divided into safe and unsafe *** a result,the convergence speed is significantly *** with the traditional DQN method in a simulation environment validated by real data,the proposed method is able to save the convergence time by 1 episode(one cooling season).The results in this paper suggest that,the proposed DQN method can achieve a much quicker learning speed without any undesired consequences,and therefore is more suitable to be used in projects without pre-learning stage.

关键词： building cooling water system cooling tower cooling water pump DQN controller convergence speed

Refill friction stir spot welding of 5083-O aluminum alloy

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Journal of Materials Science & Technology 2018年第5期34卷 878-885页

作者： Zhiwu Xu zhengwei li Shude Ji liguo Zhang State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Faculty of Aerospace Engineering Shenyang Aerospace University

In this work,refill friction stir spot welding（RFSSW） was used to weld 2 mm-thick 5083-O *** Box–Behnken experimental design was used to investigate the effect of welding parameters on the joint lap shear *** showed that a surface indentation of 0.3 mm effectively eliminated the welding *** of the stir zone（SZ） was higher than that of the base material（BM） and the hardness decreased with increasing the heat input during *** optimum failure load of 7.72 k N was obtained when using rotating speed of 2300 rpm,plunge depth of 2.4 mm and refilling time of 3.5 *** fracture modes were obtained during the lap shear test and all were affected by the hook defect.

关键词： Refill friction stir spot welding Keyhole Secondary phases Microhardness Lap shear failure load

Snoring detection based on a stretchable strain sensor

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Science China(Information Sciences) 2021年第7期64卷 224-226页

作者： zhengwei li Qingkun SONG Long CHENG Min TAN School of Automation Harbin University of Science and Technology State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of Sciences University of Chinese Academy of Sciences

Snoring is caused by the stenosis of the upper respiratory tract, which can lead to the vibration of the palatine *** brings not only harm to the snorer [1] but also sleep deprivation to those around them [2]. Furthermore, studies show that loud snorers have a 67%greater chance of suffering from a stroke and a 34%higher risk of having a heart attack. To identify people at risk from these diseases,snoring recording and analysis become highly important [3].

关键词： Snoring detection Strain sensor Sleeping quality monitoring Detection algorithm Wearable device

Multi-modal fusion for robust hand gesture recognition based on heterogeneous networks

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Science China(Technological Sciences) 2023年第11期66卷 3219-3230页

作者： ZOU YongXiang CHENG Long HAN liJun li zhengwei School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory for Management and Control of Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China

Hand gesture recognition has become a vital subject in the fields of human-computer interaction and rehabilitation *** paper presents a multi-modal fusion for hand gesture recognition(MFHG)model,which uses two heterogeneous networks to extract and fuse the features of the vision-based motion signals and the surface electromyography(s EMG)signals,*** extract the features of the vision-based motion signals,a graph neural network,named the cumulation graph attention(CGAT)model,is first proposed to characterize the prior knowledge of motion coupling between finger *** CGAT model uses the cumulation mechanism to combine the early and late extracted features to improve motion-based hand gesture *** the s EMG signals,a time-frequency convolutional neural network model,named TF-CNN,is proposed to extract both the signals'time-domain and frequency-domain *** improve the performance of hand gesture recognition,the deep features from multiple modes are merged with an average layer,and then the regularization items containing center loss and the mutual information loss are employed to enhance the robustness of this multi-modal ***,a data set containing the multi-modal signals from seven subjects on different days is built to verify the performance of the multi-modal *** experimental results indicate that the MFHG can reach 99.96%and 92.46%accuracy on hand gesture recognition in the cases of within-session and cross-day,respectively.

关键词： leap motion s EMG multi-modal graph neural network hand gesture recognition

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Effect of Reverse-threaded Pin on Mechanical Properties of Friction Stir Lap Welded Alclad 2024 Aluminum Alloy

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Journal of Materials Science & Technology 2016年第7期32卷 671-675页

作者： Yumei Yue zhengwei li Shude Ji Yongxian Huang Zhenlu Zhou Faculty of Aerospace Engineering. Shenyang Aerospace University Shenyang 110136 China State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001 China

In friction stir welding （FSW）, tool geometry plays an important role in joint quality. In order to improve mechanical properties of friction stir lap welding （FSLW）joint, a tool with a reverse-threaded pin was designed in the present study. Using 2024-T4 aluminum alloy as the research object, tools with the full- threaded pin and reverse-threaded pin were used in FSLW. Results showed that, when using the same parameter combination, FSLW joint using the reverse-threaded pin owned bigger effective sheet thick- ness （EST）, bigger lap width and better lap shear failure strength. Compared with the full-threaded pin, fracture mode of the FSLW joint changed from shear fracture mode to tensile fracture mode when the reverse-threaded pin was used. Fracture morphologies presented ductile fracture.

关键词： Friction stir lap weldingReverse-threaded pinHookFracture position

Migrating behaviors of interfacial elements and oxide layers during diffusion bonding of 6063Al alloys using Zn interlayer in air

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Journal of Materials Science & Technology 2023年第24期155卷 119-131页

作者： Pu Zhao zhengwei li Zhiwu Xu Xuesong Leng Anqi Tong Jiuchun Yan State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001 China Flexible Printed Electronics Technology Center Harbin Institute of Technology Shenzhen 518055 China University of Science and Technology liaoning Anshan 114051 China

The oxide layer on the surface has always been a key obstacle to achieving the diffusion bonding of Al *** is a challenge for performing diffusion bonding without removing oxide ***,diffusion bonding of Al alloy retaining continuous oxide layers was successfully achieved in the air by a low-temperature and low-pressure diffusion bonding mothed using a Zn *** the bonding processes,conducted at 360℃ and 3 MPa,Zn diffused into Al through cracks of thin oxide layers to form the joint composed Al/(diffusion layer)/(oxide layer)/(Zn)/(oxide layer)/(diffusion layer)/*** diffusion layers were composed of Zn-Al eutectoid,and the oxide layer included nanocrystals and amorphous Al_(2)O_(3).The shear strength of joints containing continuous oxide layers was about 30 ***,the migration behavior toward the joint center of the interfacial oxide layers was observed with consuming of the Zn *** cracking phenomenon,the“subcutaneous diffusion”and the migration behavior of oxide layers were verified and analyzed by the diffusion bonding of anodized ***,the dynamic migration mechanism of oxide layers with elements diffusion and bonding interface strengths were discussed in *** ability to join Al alloys in the air at low temperatures and low pressure suggests a highly practical and economic method for diffusion bonding.

关键词： 6063Al alloy Diffusion bonding Zn interlayer Oxide layers Migration behavior

Edaravone promotes functional recovery after mechanical peripheral nerve injury

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Neural Regeneration Research 2014年第18期9卷 1709-1715页

作者： Teng Zhang zhengwei li Jianli Dong Feng Nan Tao li Qing Yu Department of Orthopedics the Second Affiliated Hospital of Dalian Medical University

Edaravone has been shown to reduce ischemia/reperfusion-induced peripheral nerve injury. However, the therapeutic effect of edaravone on peripheral nerve injury caused by mechanical factors is unknown. In the present study, we established a peripheral nerve injury model by crushing the sciatic nerve using hemostatic forceps, and then administered edaravone 3 mg/kg intraperitoneally. The sciatic functional index and superoxide dismutase activity of the sciatic nerve were increased, and the malondialdehyde level was decreased in animals in the edaravone group compared with those in the model group. Bcl-2 expression was increased, but Bax expres- sion was decreased in anterior horn cells of the L4-6 spinal cord segments. These results indicated that edaravone has a neuroprotective effect following peripheral nerve injury caused by mechan- ical factors through alleviating free radical damage to cells and inhibiting lipid peroxidation, as well as regulating apoptosis-related protein expression.

关键词： nerve regeneration peripheral nerve injury mechanical injury sciatic nerve injury edaravone lipid peroxidation free radical damage malondialdehyde superoxide dismutase Bcl-2 Bax NSFC grant neural regeneration

Pose Estimation of Space Targets Based on Model Matching for Large-Aperture Ground-Based Telescopes

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Computer Modeling in Engineering & Sciences 2018年第11期117卷 271-286页

作者： zhengwei li Jianli Wang Tao Chen Bin Wang Yuanhao Wu Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun13033China University of Chinese Academy of Sciences Beijing100049China.

With the development of adaptive optics and post restore processing techniques,large aperture ground-based telescopes can obtain high-resolution images(HRIs)of *** pose of the space target can be estimated from HRIs by several *** the target features obtained from the image are unstable,it is difficult to use existing methods for pose *** this paper a method based on real-time target model matching to estimate the pose of space targets is ***,the physicallyconstrained iterative deconvolution algorithm is used to obtain HRIs of the space ***,according to the 3D model,the ephemeris data,the observation time of the target,and the optical parameters of the telescope,the simulated observation image of the target in orbit is rendered by a scene simulation ***,the target model searches through yaw,pitch,and roll until the correlation between the simulated observation image and the actual observation image shows an optimal *** simulation results show that the proposed pose estimation method can converge to the local optimal value with an estimation error of about 1.6349°.

关键词： Ground-based telescope pose estimation correlation matching space target image restoration