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SSRN 2024年

作者： Zhang, Hanbo Li, Chengxuan Liu, Zhenhai Ye, Hongfei Li, Hui Zheng, Yonggang State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment Department of Engineering Mechanics School of Mechanics and Aerospace Engineering Dalian University of Technology Dalian116024 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610200 China

This paper introduces an adaptive peridynamics with a correspondence material model (A-PD-CMM) to effectively simulate the coupled creep-plastic behavior and the creep crack propagation in metal materials. In this method, to describe the coupled creep-plastic deformation with considering the creep damage, the multiaxial coupled constitutive model that integrates the Wen-Tu creep damage model and the J2 plastic model is developed. Moreover, a damage associate criterion is incorporated into the peridynamics framework to effectively capture the influence of damage on the force state. To detail the rapid damage evolution during the tertiary creep stage, a time-adaptive solving strategy is proposed. Additionally, the constitutive integration algorithm of the multiaxial coupled model is efficiently realized by decoupling it into two parts, that is, an implicit computation of creep-plasticity and an explicit evolution of creep damage. The efficacy and engineering applicability of the proposed A-PD-CMM are validated through several representative numerical examples, showcasing its potential in addressing complex material behavior. © 2024, The Authors. All rights reserved.

关键词： Crack propagation

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Peridynamic Simulation for Thermal and Mechanical Behavior of Manufactured Structures with MIG Welding 1

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作者： Li, Hui Zhang, Liping Liu, Zhenyu Li, Lijuan Zhang, Yixiong Shao, Xuejiao Science and Technology On Reactor System Design Technology Laboratory Nuclear Power Institute of China No. 328 Changshun Avenue Chengdu Sichuan610200 China

ISBN: (数字)9783030683030

ISBN: (纸本)9783030683023;9783030683054

A new numerical simulation method is developed for the evaluation of thermal and mechanical analyses of manufactured structures with Metal Inert Gas (MIG) welding on the basis of the peridynamics. The peridynamic formulations of the weak coupled thermo-mechanical problems are derived based on a heat transfer model and a microplastic model. To simulate the MIG welding process, a birth–death material point method in the peridynamic framework is proposed to model the addition of weld metal to the workpiece. To simplify the calculation process and improve the computational efficiency due to no need of updating the neighbourhoods of material points, an additional scalar field is introduced in the equations to describe the birth and death states of the material points. In addition, the present method is applied to simulate a classical model of two plates being joined together by the MIG welding. The results indicate that the residual tensile deformations are formed in the welded area while the residual compressive deformations are formed far from the wild line after the release of the clamps on account of the plastic deformation. These results also demonstrate the validity of the present method for the simulation of the MIG welding by comparing with the reference solution. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Computational efficiency

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Dynamic stiffness simulation analysis of hydraulic dual-parallel actuation systems using Amesim

Dynamic stiffness simulation analysis of hydraulic dual-para...

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2024 CSAA/IET International Conference on Aircraft Utility systems, AUS 2024

作者： Li, Chuandong Wu, Shuai Wei, Renlei Chen, Taiqi Qin, Mingyuan Chu, Bing Yang, Yuliang Luo, Jianing School of Automation Science and Electrical Engineering Beihang University Beijing100191 China National Key Laboratory of Aircraft Integrated Flight Control Beihang University Beijing100191 China AVIC Shenyang Aircraft Design and Research Institute Ministry of Industry and Information Technology Beijing100191 China Key Laboratory of Advanced Aircraft Systems Beihang University Ministry of Industry and Information Technology Beijing100191 China

In the field of flight control systems, actuators play a crucial role, and dynamic stiffness stands as one of the pivotal metrics to gauge their performance, reflecting the actuators' resilience to external disturbances. Hence, investigating dynamic stiffness is paramount for enhancing the overall performance of flight control systems. This study focuses on a hydraulic dual-parallel actuator system, wherein a mathematical model is established to derive the expression for dynamic stiffness. Leveraging the Amesim software, a simulation model of the parallel actuator system is constructed to conduct an in-depth analysis of its dynamic stiffness characteristics. During simulation, sinusoidal loading forces of varying frequencies are applied at the output end of the actuator system, and displacement response data is collected. Subsequently, the Fast Fourier Transform (FFT) is employed to obtain dynamic stiffness, enabling an analysis of its variations. The relationship between the system's natural frequency and dynamic stiffness is explored, along with an investigation into the primary factors influencing dynamic stiffness. Simulation results indicate that enhancing both support and connection stiffness,reducing load mass and enlarging the piston area can enhance the system's dynamic stiffness, thereby meeting the performance requirements of flight control systems. © The Institution of Engineering & technology 2024.

关键词： Fast Fourier transforms

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Using Lock-Free design for Throughput-Optimized Cache Eviction

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Proceedings of the ACM on Measurement and Analysis of Computing systems 2025年第2期9卷 1-28页

作者： Chao Dong Fang Wang Hong Jiang Dan Feng Key Laboratory of Information Storage System Wuhan National Laboratory for Optoelectronics) Engineering Research Center of data storage systems and Technology School of Computer Science and Technology) Ministry of Education of China Huazhong University of Science and Technology Wuhan Hubei China Department of Computer Science and Engineering University of Texas at Arlington Arlington Texas USA

In large-scale information systems, storage device performance continues to improve while workloads expand in size and access characteristics. This growth puts tremendous pressure on caches and storage hierarchy in terms of concurrent throughput. However, existing cache eviction policies often struggle to provide adequate concurrent throughput due to their reliance on coarse-grained locking mechanisms and complex data structures. This paper presents a practical approach to cache eviction algorithm design, called Mobius, that optimizes the concurrent throughput of caches and reduces cache operation latency by utilizing lock-free data structures, while maintaining comparable hit ratios. Mobius includes two key designs. First, Mobius employs two lock-free FIFO queues to manage cache items, ensuring that all cache operations are executed efficiently in parallel. Second, Mobius integrates a consecutive detection mechanism that merges multiple modifications during eviction into a single operation, thereby reducing data races. Extensive evaluations using both synthetic and real-world workloads from high-concurrency clusters demonstrate that Mobius achieves a concurrent-throughput improvement ranging from 1.2× to 8.5× over state-of-the-art methods, while also maintaining lower latency and comparable cache hit ratios. The implementation of Mobius in CacheLib and RocksDB highlights its effectiveness in enhancing cache performance in practical scenarios.

关键词： cache eviction policy concurrency fifo queue lock-free throughput

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Importance of London dispersion force in stabilizing La3Ni2O7 under hydrostatic or anisotropic pressure

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Physical Review B 2024年第18期110卷 184514-184514页

作者： Junhao Peng Huafeng Dong Jingyi Zhang Renhai Wang Ping Cui Wei Zhang Zhenyu Zhang Guangdong Provincial Key Laboratory of Sensing Physics and System Integration Applications School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou Guangdong 510006 China International Center for Quantum Design of Functional Materials (ICQD) Hefei National Research Center for Physical Sciences at Microscale University of Science and Technology of China Hefei Anhui 230026 China Hefei National Laboratory University of Science and Technology of China Hefei Anhui 230088 China

Accurate determination of the bilayer structure of the recently discovered high transition temperature superconductor La3Ni2O7 under pressure is a prerequisite for understanding its electronic properties and revealing its dominant superconducting mechanism. Here we present the first systematic exploration of the structural evolution of La3Ni2O7 under different pressure schemes, with the long-range London dispersion force between neighboring bilayers taken into account explicitly. We find, within a broad pressure range of 10 to 35 GPa, that the structure is essentially always in-plane symmetric under hydrostatic pressure, in clear contradiction to the experimentally observed asymmetric structure. Nevertheless, when the applied pressure is anisotropic together with inclusion of a proper dispersion force, the asymmetric structure can be reproduced, accompanied by pronounced flat bands of dz2 orbitals around the Fermi level that in turn benefit superconductivity. These findings offer stringent constraints on developing mechanistic understanding of superconductivity of La3Ni2O7.

关键词： High-pressure studies Nickelates Superconductors Density functional calculations

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Thermally-Induced Fracture in the Oxide Scale of T91 Ferritic/Martensitic Steel after Exposure to Oxygen-Saturated Liquid Lead-Bismuth Eutectic

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SSRN 2024年

作者： Liu, Yunpeng Du, Juan Zhou, Zhikun Tian, Chenwen Liu, Zhenyu Zhang, Ying Shi, Kaikai Chen, Ziguang Department of Engineering Mechanics School of Aerospace Engineering Huazhong University of Science and Technology Wuhan430074 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan430074 China

Ensuring the continuity and stability of the oxide scale to separate T91 steel from lead-bismuth eutectic (LBE) is an effective method for limiting corrosion in the lead-based fast reactor system. In this study, we specifically investigate the impact of cooling thermal stress on the stability and damage of the oxide scales of T91 steel when exposed to oxygen-saturated liquid lead-bismuth eutectic at high temperatures. We revisit a corrosion test conducted on T91 steels exposed to stagnant oxygen-saturated LBE at 500 °C. Experimental results indicate that oxide damage exists without any external force, including interface cracks and through-scale cracks perpendicular to the interface. We develope a three-layer peridynamic model of T91-(Fe,Cr)3O4-Fe3O4 to simulate the deformation and failure of oxides under a cooling process from high temperature to room temperature. The simulation results show that a temperature drop of about 200 °C from 500 °C can cause through-oxide cracks in the oxide scale, and subsequent cooling can lead to the propagation of interfacial cracks. Additional modifications are introduced in the model to account for the porosity of the oxide scale. Parametric investigations illustrate the effects of oxide scale thickness and porosity on the resulting crack patterns. © 2024, The Authors. All rights reserved.

关键词： Oxygen

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Formally Verified a Front-End of the Trusted Code Generator for Safety I&C Software of NPPs 5th

Formally Verified a Front-End of the Trusted Code Generator ...

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5th International Symposium on Software Reliability, Industrial Safety, Cyber Security and Physical Protection of Nuclear Power Plant, ISNPP 2020

作者： Lan, Lin Ma, Quan Hou, Rong-Bin Jiang, Wei Liu, Ming-Xing Yang, Fei Li, Yong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of the China Chengdu Sichuan China Harbin Engineering University Harbin China

ISBN: (纸本)9789811634550

In nuclear power plant embedded software control area, graphical control algorithms are described by Lustre program and designed with graphical editors of engineering station. After they are translated into C programs through a code generator, then the C programs are downloaded to the embedded platform software of NASPIC. The correctness of the code generator will directly determine the credibility and safety of NASPIC. Therefore, it’s important to ensure the correctness of the code generator translation process. Formally verified the correctness of a code generator, which has been studied for many years and becomes a most effective approach to develop a trusted code generator. This article is based on the requirements of nuclear safety-level I&C (Instrumentation & Control) system and mainly presents the development of a formally verified code generator front-end. The front-end translates Lustre source program into S_Lustre (a sequential intermediate language). And it is programmed and proved in Coq (Auxiliary Theorem Prover). During the development of the front-end, two key technical challenges have been resolved. The first is to ensure every id which appeared in the Lustre program has been defined. The second is to implement the casualty analysis and determine the evaluation order of user-defined types and equations based on the dependencies. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Formal verification

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Coupled Axisymmetric Peridynamics with Stabilized Correspondence Material Model for Ablation and Fracture Problems

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SSRN 2024年

作者： Zhang, Hanbo Liu, Zhenhai Li, Chengxuan Ye, Hongfei Zhang, Hongwu Li, Hui Zheng, Yonggang State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment Department of Engineering Mechanics School of Mechanics and Aerospace Engineering Dalian University of Technology Dalian116024 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610200 China

A coupled axisymmetric peridynamics with a stabilized correspondence material model (CA-PD-SCMM) is proposed in this work to effectively simulate the ablation and ductile fracture behaviors of metals under high temperatures. To quantify the damage resulting from compression and shearing deformations, a strain energy density decomposition method is incorporated into the ductile damage model. Furthermore, a novel axisymmetric stabilization method based on peridynamics linearization theory is introduced to mitigate numerical oscillations arising from zero-energy modes in both thermal and mechanical scenarios. To capture the varying geometries and update the boundary conditions during ablation, a moving boundary model is developed based on temperature-associated criteria. To validate the capacity of the proposed CA-PD-SCMM, several representative numerical experiments are conducted. These examples not only affirm its ability to stabilize numerical oscillations in coupled axisymmetric thermoplastic problems but also demonstrate its capability for accurately simulating ablation and predicting crack propagation. © 2024, The Authors. All rights reserved.

关键词： Ductile fracture

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design of enhanced pipeline repair clamp 6

Design of enhanced pipeline repair clamp

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6th International Conference on Material Strength and Applied Mechanics, MSAM 2023

作者： Zhao, Bingjie Zhang, Shuli Hu, Jun Gao, Qijun Sun, Jingquan Lu, Linping Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin300384 China CNOOC Safety Technology Services Co. Ltd Tianjin300457 China

ISBN: (纸本)9781643684345

Based on the technical requirements for emergency repair of damaged subsea oil and gas pipelines, an enhanced pipeline repair clamp is designed. In order to facilitate the installation of subsea environment, a hydraulic cylinder auxiliary installation mechanism is designed. Based on the reinforcement requirements of damaged part of pipelines, the enhanced components are designed and the slip enhanced structure is designed. Analyzed the sealing technology of the clamp, and found that double sealing technology is adopted by the clamp, resulting in higher reliability of pipeline repair sealing. The formula for calculating the key parameters of the wall thickness of the clamp is provided. The above work can provide reference for the design and application of enhanced pipeline repair clamp. © 2023 The Authors.

关键词： Repair

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Trusted Algorithm Compiler for Safety I&C Software of NPPs Based on Formal Methods 5th

Trusted Algorithm Compiler for Safety I&C Software of NPPs B...

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5th International Symposium on Software Reliability, Industrial Safety, Cyber Security and Physical Protection of Nuclear Power Plant, ISNPP 2020

作者： Yang, Fei Lan, Lin Ma, Quan Han, Wen-Xing Liu, Ming-Xing Jiang, Wei Science and Technology On Reactor System Design Technology Laboratory Nuclear Power Institute of the China Chengdu Sichuan China Harbin Engineering University Harbin China

ISBN: (纸本)9789811634550

The algorithm for the 1E system of NPPs is generally developed by a graph making tool at the engineering station. After the executable file is generated by the compiler and downloaded to the platform software, the credibility of the executable algorithm depends on the credibility of the generated programming code. Therefore, its security requirements put high demands on the compiler. The formal method has been developed rapidly in response to the problem of trusted compilation in recent years. This paper studies the main methodology and key technological components for designing and implementing the trusted compilers, meanwhile emphasize its industrial application based on existing research. The application is optimized, and a new composite compilation architecture is proposed, which reduces the difficulty of proof work and enhances the flexibility of the compiler’s later phase. Finally, several compiler optimization procedures for the security level software NASPIC are studied, and the algorithm compilation is enhanced, as well as the trusted performance of the device. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Formal verification

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