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Prognostics and system Health Management Conference (PHM-Qingdao)

作者： Pengfei Gou Daiwei Zheng Lei Tang Mengjuan Liu School of Information and Software Engineering University of Electronic Science and Technology of China UESTC Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China NPIC Chengdu China

ISBN: (数字)9798350354010

ISBN: (纸本)9798350354027

Prognostics and Health Management (PHM) is currently the mainstream solution for the condition monitoring and maintenance of industrial systems. In PHM, the system condition is monitored by monitoring the operational status parameters of the system to diagnose equipment faults, predict the remaining useful life, etc. Utilizing sequential operational status parameters to complete prediction and classification tasks is usually modeled as a time series processing task. Therefore, a high-performance time series prediction model is crucial for PHM. This paper focuses on the use of time series prediction models to achieve the prediction of key state parameters of the nuclear power system. However, there are still some challenges when directly applying existing time series prediction models to industrial systems. First, obtaining operational data on the nuclear power system is relatively difficult, resulting in a small amount of training data, which causes many models to face the risk of insufficient training or overfitting. Second, most of the existing time series prediction models are composed of high- and low-frequency decoupling modules, while the operational data of nuclear power systems often have fewer high-frequency components, making it difficult for many existing SOTA models to achieve good results. In order to address these challenges, we have developed a Transformer-based time series prediction model with contrastive learning for monitoring the status of nuclear power systems. We evaluated the new model on three nuclear power simulation datasets and four power transformer datasets. The experimental results show that the new model's performance is superior to baseline models. We also proved the effectiveness of our improvement through ablation experiments.

关键词： Training Time series analysis Training data Contrastive learning Predictive models Data models Power systems Power transformers Prognostics and health management Monitoring

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NUMERICAL STUDY OF HEAT TRANSFER ENHANCEMENT IN NARROW RECTANGULAR CHANNEL WITH ROTATED ELLIPTIC DIMPLE WITH INCLINED SLIT 29

NUMERICAL STUDY OF HEAT TRANSFER ENHANCEMENT IN NARROW RECTA...

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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Wang, Chuntao Lu, Qi Qiu, Xiang Liu, Yu Deng, Jian Sun, Jie School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an China Key Laboratory of Nuclear Reactor System Design Technology Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791886434

In order to enhance heat transfer performance of the reactor core coolant in the narrow rectangular channel of nuclear power system and ensure the safety of the reactor core without local high temperature as well as not cause excessive pressure loss, three different shapes of protruded elliptic dimple were adopted in the channel for numerical research. Firstly, the angle between long axis of the elliptic dimple and direction of the mainstream was rotated, which was defined as a rotated angle θ ranging from 0° to 90°. Secondly, streamwise (in line with the mainstream) slit was processed on the dimple. The last, inclined slit was processed on the dimple. There were five quantitative and two qualitative indicators to account for comprehensive effects of heat transfer, flow resistance and temperature distribution on the wall of the channel, namely, Nu for heat transfer capacity, f for flow resistance, performance evaluation criteria PEC for combination of heat transfer and flow resistance, T max and Tavg for maximum and average temperature on the outer wall respectively, velocity field near the inner wall and temperature distribution on the outer wall to show more detail information of the flow and heat transfer characteristics. The study results showed that with increase of θ, heat transfer efficiency and flow resistance all increased. Dimple with whether streamwise slit or inclined slit helped to reduce flow resistance. The dimple with streamwise slit performed best in flow resistance performance and the dimple with inclined slit performed best in heat transfer performance. Copyright © 2022 by ASME.

关键词： Temperature distribution

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APPLICATION OF THE METHOD OF MANUFACTURED SOLUTIONS TO VERIFY A NUCLEAR reactor PHYSICS COMPUTATIONAL CODE USING THE METHOD OF CHARACTERISTICS 30

APPLICATION OF THE METHOD OF MANUFACTURED SOLUTIONS TO VERIF...

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30th International Conference on Nuclear Engineering, ICONE 2023

作者： Ge, Wenjia Wen, Peizheng Li, Zhuofan Luo, Qi Zhao, Chen Wang, Jipu Yang, Ming Institute for Advanced Study in Nuclear Energy & Safety College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China Nuclear Reactor System Design Technology Key Laboratory China Nuclear Power Research and Design Institute Chendu China

ISBN: (纸本)9784888982566

The method of characteristics (MoC) has become an accepted tool for lattice physics calculations. MoC has many advantages such as accurate representations of both the lattice geometry and the boundary conditions. The flat source (FS) approximation is most commonly used, and the linear source (LS) approximation can improve the accuracy by preserving higher order spatial moments of the neutron source. However, as a non-standard spatial discretization method, the order of accuracy of the spatial discretization is more difficult to obtain, especially for analyzing linear source approximation, because the MoC method utilizes two sets of spatial meshes - the FS mesh and the set of characteristic rays that integrate the transport equation over the FS mesh. In this work, we analyze the order of accuracy with spatial resolution in MoC in planar geometry for both FS and LS approximations and verify our predictions with the Method of Manufactured Solutions (MMS). It is shown that the flat source approximation is second order accurate and that the linear source approximation has a fourth order accuracy. © 2023 by JSME.

关键词： Nuclear reactors

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RESEARCH ON THE FILM THICKNESS CHARACTERISTICS OF JET CONDENSER NOZZLE 31

RESEARCH ON THE FILM THICKNESS CHARACTERISTICS OF JET CONDEN...

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2024 31st International Conference on Nuclear Engineering, ICONE 2024

作者： Weiyu, Chu Chonghai, Huang Qi, Xiao Zhaoming, Meng Yilin, Fu Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin China Science and Technology on Thermal Energy and Power Laboratory Wuhan Second Ship Design and Research Institute Wuhan China

ISBN: (纸本)9780791888261

Owing to the expansive applicability of jet condensers across diverse sectors, juxtaposed with the paucity of scholarly investigation into the morphological characteristics of the condenser liquid film, the present study zeroes in on the determinants of film thickness attributable to jet condenser nozzles. In pursuit of this objective, we engineered and actualized a visualization experimental apparatus tailored for the meticulous examination of the film-forming propensities of such nozzles. Subsequent experimental endeavors focused on the dynamics of nozzle-induced spray film genesis. Leveraging bespoke measurement techniques, this inquiry delved into the influence of varied parameters including flow rate and nozzle angle, on the film thickness engendered by the nozzles, thereby elucidating discernible trends in the phenotypical attributes of nozzle film thickness. Findings from this research suggest a proportional relationship between film thickness and flow rate, and an inverse correlation between nozzle diameter and film thickness. These insights furnish empirical underpinnings for the refinement of nozzle configurations in jet condensers, thereby contributing to the enhancement of their operational efficacy. © 2024 by ASME.

关键词： Film thickness

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High-Performance in N-Type Pbte Thermoelectric Materials by Defects Management and Extraordinary Role of Cd Alloying

SSRN

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SSRN 2024年

作者： Chen, Zhiyu Li, Mancang Chen, Zhang Wang, Yu Zhou, Daijie Huang, Xueliang Zhang, Xinhu Guo, Rui Liu, Xianbo Wang, Zhengshang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Sichuan Research Center of New Materials Chengdu610000 China

The conventional multiple isovalent alloying is proved to be effective for enhancing n-type PbTe thermoelectrics. However, the introduction of various elements undeniably leads to potential stability concerns during material application. Here, we propose a straightforward strategy that leverages Cd alloying and defect management to enhance the TE performance of n-type PbTe. The Cd doping facilitates band gap widening, resulting in increased effective mass and Seebeck coefficient, especially at elevated temperatures due to the improved Cd solubility. Furthermore, the introduction of excess Pb atoms serves to occupy intrinsic Pb vacancies, consequently enhancing carrier mobility. As a result, the maximum power factor of Cd-alloyed Pb1.01Te samples reaches 31.5 μW cm-1 K-2, signifying a remarkable improvement of 69.3% in comparison to pristine PbTe. Additionally, the enlarged band gap induced by Cd alloying also effectively mitigates bipolar diffusion, combining with the enhanced phonon scattering due to CdTe secondary phase, yields a 34.3% decrease in thermal conductivity. By harnessing the multifaceted effects of Cd alloying and defect management, the ZT value of Pb1.01Te-2%Cd samples reaches 1.35 at 782 K. The present findings provide a novel perspective on the versatile utilization of single isovalent element alloying and the optimization of performance across other TE materials. © 2024, The Authors. All rights reserved.

关键词： Energy gap

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Air-Ground Collaborative Control for Angle-Specified Heterogeneous Formations

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent Vehicles 2024年 1-13页

作者： Chen, Liangming Xiao, Jiaping Teo, Clarence Wei Rui Li, Jianqing Feroskhan, Mir School of System Design and Intelligent Manufacturing and Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and Technology Shenzhen China school of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore College of Communication Engineering Hangzhou Dianzi University Hangzhou China

The need for better search and rescue capabilities has led to the increased demand for collaborative aerial-ground multi-robot deployments. However, most existing solutions require high communication bandwidth or bulky sensor equipment that is not suitable especially for aerial robots. To make the execution of these tasks more efficient, this paper proposes an angle-specified heterogeneous leader-follower formation framework consisting of unmanned aerial vehicles (UAVs) flying in a 3D space and ground robots moving in a 2D plane. The UAVs are controlled to maintain a desired angle-specified formation with the first three UAVs as the leaders forming a triangular shape and the remaining UAVs as the followers. The follower UAVs only need direction measurements to track the leader UAVs. For the ground robots, two leader robots track the UAV group and determine the orientation and scale of the ground formation, while the follower robots track the leader robots using only direction measurements. The proposed heterogeneous formation framework is energy-efficient as most robots only require low-cost and lightweight direction measurements. The stability of the proposed formation control algorithms is proved and validated through various physical application experiments. IEEE

关键词： Multi agent systems

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Bioinspired polysaccharide-based nanocomposite membranes with robust wet mechanical properties for guided bone regeneration

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National science Review 2024年第3期11卷 215-226页

作者： Jian-Hong Xiao Zhen-Bang Zhang JiaHao Li Si-Ming Chen Huai-Ling Gao YinXiu Liao Lu Chen ZiShuo Wang YiFan Lu YuanZhen Hou HengAn Wu DuoHong Zou Shu-Hong Yu Department of Chemistry New Cornerstone Science Laboratory Institute of Biomimetic Materials&Chemistry Anhui Engineering Laboratory of Biomimetic MaterialsDivision of Nanomaterials&Chemistry Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of China Department of Dental Implant Center Stomatologic Hospital and College Key Laboratory of Oral Diseases Research of Anhui Province Anhui Medical University CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Department of Oral Surgery College of Stomatology National Clinical Research Center for Oral DiseasesShanghai Key Laboratory of Stomatology Shanghai Research Institute of Stomatology Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine Institute of Innovative Materials(I2M) Department of Chemistry Department of Materials Science and Engineering Southern University of Science and Technology

Polysaccharide-based membranes with excellent mechanical properties are highly desired. However, severe mechanical deterioration under wet conditions limits their biomedical applications. Here, inspired by the structural heterogeneity of strong yet hydrated biological materials, we propose a strategy based on heterogeneous crosslink-and-hydration（HCH） of a molecule/nano dual-scale network to fabricate polysaccharide-based nanocomposites with robust wet mechanical properties. The heterogeneity lies in that the crosslink-and-hydration occurs in the molecule-network while the stress-bearing nanofiber-network remains unaffected. As one demonstration, a membrane assembled by bacterial cellulose nanofiber-network and Ca2+-crosslinked and hydrated sodium alginate molecule-network is designed. Studies show that the crosslinked-and-hydrated molecule-network restricts water invasion and boosts stress transfer of the nanofiber-network by serving as interfibrous bridge. Overall, the molecule-network makes the membrane hydrated and flexible; the nanofiber-network as stress-bearing component provides strength and *** HCH dual-scale network featuring a cooperative effect stimulates the design of advanced biomaterials applied under wet conditions such as guided bone regeneration membranes.

关键词： bioinspiration heterogeneous crosslink-and-hydration dual-scale network nanocomposite membrane wet mechanical properties guided bone regeneration

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Preliminary Development and Validation of Acena Code for Melting and Freezing Behavior Simulation

SSRN

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SSRN 2024年

作者： Lin, Yue Zhang, Dalin Chen, Yutong Zhang, Xisi Deng, Jian Tian, Wenxi Qiu, Suizheng Su, Guanghui Shaanxi Xi’an710049 China Institute of Reactor Engineering Technology China Institute of Atomic Energy Beijing102413 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China

Melting and freezing model plays a crucial role in safety analysis for liquid metal fast reactors under core disruptive accidents. Thus, it’s necessary to establish suitable models for accurate prediction of molten materials migration after severe accidents happens. In this study, a kind of melting and freezing model is established in ACENA code. And the ACENA code is used to simulate the freezing behavior of melt and calculated results are compared with experimental results to verify the applicability of the model. According to the comparison it is shown that the simulation results by ACENA code agree well with experimental results. Both the changing trend and final value of penetration depth of melt are consistent with realistic conditions. Besides, the effects of heat exchange on penetration depth are also analyzed. This research contributes to the development of safety analysis tools for liquid metal reactors under severe accidents. © 2024, The Authors. All rights reserved.

关键词： Melting

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Super-Twisting Control for Re-entry Rigid-Elastic Coupled Hypersonic Vehicles

Super-Twisting Control for Re-entry Rigid-Elastic Coupled Hy...

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2023 China Automation Congress, CAC 2023

作者： Tang, Wentao Fan, Junfang Ji, Yi Li, Yafeng Xu, Xiaobin Zang, Luyao Beijing Information Science and Technology University Beijing Key Laboratory of High Dynamic Navigation Technology Beijing China School of Automation Beijing Information Science and Technology University Beijing China The System Design Institute of Mechan-ical-Electrical Engineering Beijing China

ISBN: (纸本)9798350303759

A super-twisting control strategy is proposed to tackle the complex problem of attitude stabilization control for rigid-elastic coupled hypersonic vehicles experiencing significant aerodynamic perturbations. Initially, the elastic modes are treated as uncertain factors, leading to the construction of a control-oriented dynamic model. To design the attitude subsystem, a combination of a super-twisting algorithm and a non-singular terminal sliding mode is proposed. A first-order differentiator is introduced to address the 'derivative explosion' issue commonly found in traditional control methods, thus eliminating the need for intricate differential computations. Moreover, a switching control strategy is integrated into the nonlinear feedback control law design, ensuring robust velocity tracking. Simulation results validate that the proposed control method surpasses conventional methods in both tracking performance and robustness. © 2023 IEEE.

关键词： Sliding mode control

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Terahertz circularly polarized detection structures based on metasurfaces with high transmittance and extinction ratio 2

Terahertz circularly polarized detection structures based on...

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Advanced Optical Manufacturing Technologies and Applications 2022, AOMTA 2022 and 2nd International Forum of Young Scientists on Advanced Optical Manufacturing, YSAOM 2022

作者： Yang, Bowei Ouyang, Mingzhao Ren, Hang Zhang, Ziqiang Fu, Yuegang School of Optoelectronic Engineering Changchun University of Science and Technology Changchun130022 China Key Laboratory of Optoelectronic Measurement and Optical Information Transmission Technology Ministry of Education Changchun University of Science and Technology Changchun130022 China Key Laboratory of Advanced Optical System Design and Manufacturing Technology The Universities of Jilin Province Changchun130022 China

ISBN: (纸本)9781510661264

Circularly polarized light is widely used in wireless communications, polarized imaging and circular dichroism spectroscopy. The existing miniature circular polarization detection structure cannot guarantee high transmission efficiency and extinction ratio at the same time. In this paper, we propose a terahertz circularly polarized detection metasurface based on dielectric materials. The proposed structure can well distinguish the handedness of circularly polarized light. At 2.3Thz, the transmission efficiency is greater than 95% and the extinction ratio is greater than 250dB. I believe our design could facilitate the development of devices such as small biomedical imaging. © 2023 SPIE.

关键词： Circular polarization

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