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NUMERICAL STUDY OF CAVITATION ON THE SURFACE OF THE GUIDE VANE IN THREE GORGES HYDROPOWER UNIT

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Journal of Hydrodynamics 2010年第5期22卷 703-708页

作者： PENG Yu-cheng CHEN Xi-yang CAO yan HOU Guo-xiang School of energy and Power Engineering Huazhong University of Science and Technology Wuhan 430074 China college of Electronic information Engineering Wuhan Polytechnic Wuhan 430074 China School of Traffic science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Large-area erosions such as rust and obvious cavitation were found on the surface of the guide vane in Three Gorges hydropower units. A numerical explanation of the cavitation is given in this article. At first, based on the characteristic performance curves of the prototype hydro-turbine supplied by ALSTOM together with the actual operating conditions, an operating point is chosen for numerical analysis using the Reynolds-Averaged Navier-Stokes （RANS） equations. The flow passages from the inlet of the spiral case to the outlet of the draft tube are included in the computational domain. The results show that the static pressure on the guide vane surface is much higher than the critical pressure of cavitation. Secondly, a tiny protrusion on the guide vane surface is considered and the problem is simplified to a 2-D problem to study the local detailed flow near the guide vane surface. The protrusion is 0.5 mm in height and is 5.0 mm in width. On the basis of the results of RANS simulations, the 2-D problem is studied using the Large Eddy Simulation （LES）. It is shown that there exists a region in which the static pressure reaches a level below the vapor pressure of the water. Thirdly, a cavitation model is included for the 0.5 mm protrusion case and another tiny pit case, with a tiny pit 0.3 mm in depth and 1.0 mm in width. The results show that vapor bubble exists at the protrusion entrance and the pit exit as the low pressure regions.

关键词： cavitation guide vane numerical analysis

Size effect of the elastic modulus of rectangular nanobeams:Surface elasticity effect

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Chinese Physics B 2013年第10期22卷 424-428页

作者：姚海燕云国宏范文亮 college of Ordos Inner Mongolia University Inner Mongolia Key Laboratory of Nanoscience and Nanotechnology college of Physical science and technology Inner Mongolia University college of Physics and Electronic information Inner Mongolia Normal University

The size-dependent elastic property of rectangular nanobeams （nanowires or nanoplates） induced by the surface elas- ticity effect is investigated by using a developed modified core-shell model. The effect of surface elasticity on the elastic modulus of nanobeams can be characterized by two surface related parameters, i.e., inhomogeneous degree constant and surface layer thickness. The analytical results show that the elastic modulus of the rectangular nanobeam exhibits a distinct size effect when its characteristic size reduces below 1 O0 nm. It is also found that the theoretical results calculated by a mod- ified core-shell model have more obvious advantages than those by other models （core-shell model and core-surface model） by comparing them with relevant experimental measurements and computational results, especially when the dimensions of nanostructures reduce to a few tens of nanometers.

关键词： size effects elastic modulus nanobeams surface elasticity

Effect of Vacancy Defects on the Properties of CoS_(2) and FeS_(2)

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Journal of Wuhan University of technology(Materials science) 2024年第3期39卷 627-638页

作者：冯中营 ZHANG Jianmin WANG Xiaowei yanG Wenjin JING Yinlan yanG yan Department of science Taiyuan Institute of TechnologyTaiyuan 030008China computational Physics Research Center Taiyuan In-stitute of TechnologyTaiyuan 030008China college of Physics and information technology Shaanxi Normal UniversityXi’an 710119China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Department of Physics College of ScienceNorth University of ChinaTaiyuan 030051China

In order to explore the effect of vacancy defects on the structural,electronic,magnetic and optical properties of CoS_(2) and FeS_(2),first-principles calculation method was used to investigate the *** calculated results of materials without vacancy are consistent with those reported in the literatures,while the results of materials with vacancy defect were different from those of literatures due to the difference vacancy *** Co vacancy defect hardly changes the half-metallic characteristic of CoS_(2).The Fe vacancy defect changes FeS_(2) from semiconductor to half-metal,and the bottom of the spin-down conduction band changes from the p orbital state of S to the d(t_(2g))orbital state of Fe,while the top of the valence band remains the d orbital d(eg)state of *** half-metallic Co vacancy defects of CoS_(2) and Fe vacancy defects of FeS_(2) are expected to be used in spintronic devices.S vacancy defects make both CoS_(2) and FeS_(2) *** the Co and S vacancy defects lead to the decrease of the magnetic moment of CoS_(2),while both the Fe and S vacancy defects lead to the obvious magnetic property of FeS_(2).Vacancy defects enhance the absorption coefficient of infrared band and long band of visible light obviously,and produce obvious red shift phenomenon,which is expected to be used in photoelectric devices.

关键词： cobalt disulfide iron disulfide vacancy defect fist principles

Bioinspired sensing-memory-computing integrated vision systems: biomimetic mechanisms, design principles, and applications

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science china(information sciences) 2024年第5期67卷 5-27页

作者： Yujie HUANG Yinlong TAN yan KANG Yabo CHEN Yuhua TANG Tian JIANG Institute for Quantum information and State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology college of Advanced Interdisciplinary Studies National University of Defense Technology Institute for Quantum science and technology College of ScienceNational University of Defense Technology

With the explosion of sensory data in the Internet of Things(Io T) era, conventional machine vision systems are becoming increasingly difficult to meet the requirements of high efficiency, low energy consumption, and low latency due to their inherent shortcomings of separate sensing, memory, and computing units. Inspired by the retina and neuromorphic computing, the sensing-memory-computing integrated vision system(SMCVS) that features low power consumption, low latency, and high parallelism has been considered a promising technology to surpass the von Neumann architecture and realize strong artificial ***, novel materials like two-dimensional semiconductors and quantum dots with novel optoelectronic performance provide hardware carriers for implementing integrated sensing-memory-computing architectures,attracting considerable attention. This paper reviews the recent research progress in bioinspired vision systems in terms of biomimetic mechanisms, design principles, computational architectures, and ***, the biomimetic mechanisms are illustrated to guide the design of high-performance artificial visual perception systems. Then the research progress of optoelectronic-synapse-based bioinspired vision systems in the device principles and applications including image filtering, color recognition, visual adaptation, and motion detection are summarized. Finally, the challenges and future developing directions of the SMCVS are provided regarding bionic application, architecture design, and device fabrication.

关键词： sensing-memory-computing architecture neuromorphic computing retinomorphic device image recognition visual system

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一类NLS-mKdV方程族的扩展可积系统

物理学报 2003年第9期52卷 2109-2113页

作者：张玉峰闫庆友山东科技大学信息学院数学研究所山东财政学院经济统计系济南250014

利用代数变换 ,构造了与文献 [5 ]中的loop代数 A2 的子代数等价的loop代数 A1 的一个子代数 A1 .再将 A1 扩展为一个高维的loop代数 G .利用 G设计了一个等谱问题 ,结合子代数间的直和运算和同构关系 ,得到了NLS_mK dV方程族的... 详细信息

利用代数变换 ,构造了与文献 [5 ]中的loop代数 A2 的子代数等价的loop代数 A1 的一个子代数 A1 .再将 A1 扩展为一个高维的loop代数 G .利用 G设计了一个等谱问题 ,结合子代数间的直和运算和同构关系 ,得到了NLS_mK dV方程族的一类扩展可积系统 .作为约化情形 ,求得了著名的Schr

关键词： NLS-mKdV方程族扩展可积系统代数变换 loop代数等谱问题可积耦合系统孤立子

SpikingMiniLM: energy-efficient spiking transformer for natural language understanding

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science china(information sciences) 2024年第10期67卷 115-128页

作者： Jiayu ZHANG Jiangrong SHEN Zeke WANG Qinghai GUO Rui yan Gang PAN Huajin TANG college of Computer science and technology Zhejiang University The State Key Lab of Brain-Machine Intelligence Zhejiang University Collaborative Innovation Center of Artificial Intelligence Zhejiang University Advanced Computing and Storage Laboratory Huawei Technologies Co. Ltd. college of Computer science and technology Zhejiang University of Technology MOE Frontier science Center for Brain science and Brain-Machine Integration Zhejiang University

In the era of large-scale pretrained models, artificial neural networks（ANNs） have excelled in natural language understanding（NLU） tasks. However, their success often necessitates substantial computational resources and energy consumption. To address this, we explore the potential of spiking neural networks（SNNs） in NLU——a promising avenue with demonstrated advantages, including reduced power consumption and improved efficiency due to their event-driven characteristics. We propose the SpikingMiniLM,a novel spiking Transformer model tailored for natural language understanding. We first introduce a multi-step encoding method to convert text embeddings into spike trains. Subsequently, we redesign the attention mechanism and residual connections to make our model operate on the pure spike-based paradigm without any normalization technique. To facilitate stable and fast convergence, we propose a general parameter initialization method grounded in the stable firing rate principle. Furthermore, we apply an ANN-to-SNN knowledge distillation to overcome the challenges of pretraining SNNs. Our approach achieves a macro-average score of 75.5 on the dev sets of the GLUE benchmark, retaining 98% of the performance exhibited by the teacher model MiniLMv2. Our smaller model also achieves similar performance to BERTMINIwith fewer parameters and much lower energy consumption, underscoring its competitiveness and resource efficiency in NLU tasks.

关键词： spiking neural networks natural language understanding spiking Transformer spike-based attention multi-step encoding ANN-to-SNN distillation

A Multi-objective Optimization based on Hybrid Quantum Evolutionary Algorithm in Networked Control System

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A Multi-objective Optimization based on Hybrid Quantum Evolu...

RGB oralscan video-based orthodontic treatment monitoring

2010 2nd International Conference on Multimedia and computational Intelligence (ICMCI 2010)

作者： QU Zheng-geng 1 2 1.college of information science and technology Northwest University Xi’an {4. ZHANG Xiao-yan 1 2 2.Deptment of Computer science Shangluo University Shangluo {4.

This paper proposed a new hybrid quantum clone evolutionary algorithm(HQCEA)in a two-layer networked learning control system(NLCS)*** special architecture achieves better control perform

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science china(information sciences) 2024年第1期67卷 124-139页

作者： yan TIAN Hanshi FU Hao WANG Yuqi LIU Zhaocheng XU Hong CHEN Jianyuan LI Ruili WANG School of Computer science and technology Zhejiang Gongshang University Shining3D Tech Co. Ltd. School of information and technology Monash University School of Mathematical and computational sciences Massey University Department of Stomatology Zhejiang Provincial People's HospitalHangzhou Medical College School of Computer and Computing science Zhejiang University City College

Orthodontic treatment monitoring involves using current images and previous 3D models to estimate the relative position of individual teeth before and after orthodontic *** process differs from image-based object 6D pose estimation due to the gingiva deformation and varying pose offsets for each tooth during *** by the fact that the poses of molars remain relatively fixed in implicit orthodontics,we design an approach that employs multiview pose evaluation and bidirectional temporal propagation for jaw pose estimation and then employs an iteration-based method for tooth *** handle changes in tooth appearance or location with weak texture across frames,we also introduce an instance propagation module that leverages positional and semantic information to explore instance relations in the temporal *** evaluated the performance of our approach using both the Shining3D tooth pose dataset and the Aoralscan3 tooth registration *** experimental results demonstrate remarkable accuracy improvements compared with existing methods.

关键词： digital dentistry object 6D pose estimation deep learning computer vision

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基于实体行为的动态碰撞检测算法研究

系统仿真学报 2009年第5期21卷 1380-1383页

作者：田尊华赵龙贾焰国防科学技术大学计算机学院长沙410073

碰撞检测算法的效率对虚拟战场的规模和真实感具有重要影响。提出了基于实体行为的动态碰撞检测方法,利用虚拟实体行为信息来减少静态碰撞检测的频率和次数。采用坐标投影法预测实体间最近可能发生碰撞的时间,有效地减少了每次动态碰撞... 详细信息

碰撞检测算法的效率对虚拟战场的规模和真实感具有重要影响。提出了基于实体行为的动态碰撞检测方法,利用虚拟实体行为信息来减少静态碰撞检测的频率和次数。采用坐标投影法预测实体间最近可能发生碰撞的时间,有效地减少了每次动态碰撞检测的计算量。分析表明,该碰撞检测算法的计算复杂度与动态实体数目成线性关系。

关键词：动态碰撞检测虚拟战场实体行为坐标投影法