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基于多尺度偏移感知网络的结肠息肉目标检测

陕西科技大学学报 2025年第1期43卷 177-184页

作者：池晓鑫杜晓刚王营博雷涛陕西科技大学电子信息与人工智能学院陕西省人工智能联合实验室陕西西安710021

一些息肉目标检测方法难以充分提取全局及长距离语义信息,导致在具有环境噪声的情况下对尺寸差异较大的息肉目标检测精度低.为了解决该问题,提出了一种基于多尺度偏移感知的息肉检测网络.首先,设计了多尺度偏移感知注意力模块,通过在不... 详细信息

一些息肉目标检测方法难以充分提取全局及长距离语义信息,导致在具有环境噪声的情况下对尺寸差异较大的息肉目标检测精度低.为了解决该问题,提出了一种基于多尺度偏移感知的息肉检测网络.首先,设计了多尺度偏移感知注意力模块,通过在不同尺度上对图像特征进行注意力加权和偏移感知,提高了图像特征的提取和融合能力.其次,设计了渐近特征融合模块,对不同尺度的特征图进行自适应空间加权融合,从而捕捉了更丰富的上下文信息.通过大量实验证明,该方法在三个不同类型的息肉数据集上分别达到了94.8%、94.6%和95.8%的检测精度,相比于当前主流的目标检测方法取得了更好的检测结果.

关键词：医学图像息肉检测注意力机制多尺度特征特征融合

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L^p-estimates on a ratio involving a Bessel process

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 158-163页

作者： LU Li-gang YAN Li-tan XIANG Li-chi Basic College Zhejiang Wanli University Ningbo 315101 China Department of Mathematics College of Science Donghua University Shanghai 200051 China

Let Z=（ Zt）t≥0 be a Bessel process of dimension δ（ δ〉0） starting at zero and let K（t） be a differentiable function on [0,∞） with K（t）〉0 （A↓t≥0）. Then we establish the relationship between L^p-norm of log^1/2（1 ＋δJτ） and L^p-norm of sup Zt[t＋k（t）]^-1/2 （0≤t≤τ） for all stopping times τ and all 0〈p〈＋∞.As an interesting example, we show that ｜｜log^1/2（1＋δLm＋1（τ）｜｜p and ｜｜supZtП[1＋Lj（t]^1/2｜｜p （0≤j≤m,j∈Z;0≤t≤τ） are equivalent with 0〈p〈＋∞ for all stopping times rand all integer numbers m, where the function Lm（t）（t≥0） is inductively defined by Lm＋1（t）=log[ 1 ＋Lm（t）] with L0（t）= 1.

关键词： Bessel processes Diffusion process Ito's formula Domination relation

Numerical Analysis on Rotary Forging Mechanism of a Flange

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Journal of Materials Science & Technology 2001年第1期17卷 129-130页

作者： gang LIU Shijian YUAN Mingxue ZHANG Longbiao chi School of Materials Science and Engineering Harbin institute of TechnologyHarbin 150001China Jilin Chemical industry Corporation China

A numerical simulation on the rotary forging process of a flange is conducted by three-dimensional rigid-plastic finite element method. The states of stress and strain rate in the workpiece are analyzed and the forging mechanism of the flange is reveal6d. Moreover, the influence of the die configuration on the material flow is also analyzed.

关键词： finite element method numerical simulation rotary forging material flow strain rate

Carbide precipitation and element distribution in high Co-Ni secondary hardening steel

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Journal of Iron and Steel Research International 2018年第3期25卷 340-346页

作者： Chen-chongWang chi Zhang Zhi-gang Yang Jie Su State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua University Beijing 100084 China Institute for Structural Materials Central Iron and Steel Research Institute Beijing 100081 China

As the increasing need of the steels with both high strength and hydrogen embrittlement resistance ability, carbide precipitation and element distribution in high Co-Ni secondary hardening steel were concerned. Carbide precipitation and element distribution in M54 were observed using carbon replicas method. Both simulation and observation results showed that MC and M2C formed in the steel. MC was round particle, which would act as grain refiners. And MzC was needle-like phase, which would be remarkable strengthening phases. Nb and V were main metallic elements in MC phase. Mo and Cr were main metallic elements in MzC phase. W, Co, and Ni were probably mainly dissolved in the matrix. As the carbide precipitation in AerMetl00 was M2C, which had similar size and shape with M2C in M54, the tensile strength and yield strength of AerMetl00 and M54 were similar. Compared with traditional high Co-Ni secondary hardening steel, M54 had higher hydrogen embrittlement resistance ability, probably because of element W in the matrix.

关键词： Carbide precipitation Element distribution Carbon replicas method Secondary hardening steel Thermodynamic simulation

Oxygen Atom Exchange Mechanism in Reaction of OH Radical with AsO

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Chemical Research in chinese Universities 2002年第3期18卷 341-344页

作者： chi Yu-juan YU Hai tao FU hong gang HUANG Xu ri LI Ze sheng SUN chia chung College of Chemistry and Chemical Engineering Heilongjiang UniversityHarbin 150080P.R.China State Key Laboratory of Theoretical and Computational Chemistry Institute of Theoretical ChemistryJilin UniversityChangchun 130023P.R.China

Oxygen atom exchange reaction mechanism in the reaction of OH radicals with AsO was investigated by means of the density functional theory (DFT) with 6 311++G( 3df,3pd ) and 6 311++G( d,p ) basis sets. The calculated results suggest that the reaction between OH and AsO should make the oxygen atoms exchange rapidly because the barrier to isomerization is significantly less than the HO-AsO bond dissociation energy.

关键词： HOAsO radical Density functional theory Oxygen atom exchange

Experimental and theoretical analysis of equilibrium segregation and radiation-induced segregation of Cr at grain boundariesin a reduced activation ferritic/martensitic(RAFM)steel

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Journal of Iron and Steel Research International 2021年第4期28卷 445-452页

作者： Li-dong Xia Hao Chen Zhi-gang Yang chi Zhang Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Helium ion irradiation at 350℃was performed to study equilibrium segregation and radiation-induced segregation(RIS)of Cr at grain boundaries in reduced activation ferritic/martensitic *** concentration at grain boundary was measured by scanning transmission electron microscopy with an energy-dispersive *** measured Cr concentration at grain boundaries in heat treated zone was 11.7 and 12.8 wt.%in irradiated zone,respectively,which matched well to the calculated results from Mclean and modified Perk *** segregation and RIS of Cr mechanisms were theoretically *** analysis indicates that as temperature rises,equilibrium Cr segregation decreases monotoni-cally,while RIS of Cr has a bell-shape profile,which increases first and then *** is also shown that at low and high temperatures,equilibrium segregation of Cr is higher than that of RIS;at intermediate temperatures,equilibrium Cr segregation is lower than RIS.

关键词： Reduced activation ferritic/martensitic steel Equilibrium Cr segregation Radiation-induced segregation Grain boundary Rate theory Mclean equation

Precipitate Behavior in Fe–20Cr–30Ni–2Nb Austenitic Heat-Resistant Steel

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 424-429页

作者： Hiroki Ishikawa chi Zhang Sheng-Wei Chen Zhi-gang Yang School of Materials Science and Engineering Tsinghua University Department of Chemistry and Materials Science Tokyo Institute of Technology

In this study, the precipitation behavior of a new austenitic heat-resistant steel （Fe-20Cr-30Ni-2Nb, in at%） was investigated. The effects of alloying addition of boron （B） and lanthanum （La） on the microstructure of the austenitic steel were scrutinized using SEM, EPMA, TEM, and XRD. The results showed that the addition of B enhanced the precipitation of bar-type Laves phase. A small precipitate with high La concentration was observed at the grain boundary in the alloy without aging; similar precipitates without La also presented in region adjacent to the La single phase. This result indicates that La can exist independently and does not contribute to the formation of new compounds. However, in both B- and La-modified alloy, B appeared in the precipitate free zone. In the alloy containing both B and La, only Fe2Nb Laves- phase precipitates, as indicated by the XRD result.

关键词： Precipitation free zone Grain boundary Phase transformation Microstructure Fe-20Cr-30Ni-2Nb austenitic heat-resistant steel

Variation in retained austenite content and mechanical properties of 0.2C–7Mn steel after intercritical annealing

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International Journal of Minerals,Metallurgy and Materials 2016年第2期23卷 161-167页

作者： Chuan Zhao chi Zhang Wen-quan Cao Zhi-gang Yang School of Materials Science and Engineering Tsinghua University Institute for Structural Materials Central Iron and Steel Research Institute

The effects of annealing time and temperature on the retained austenite content and mechanical properties of 0.2C-7Mn steel were *** retained austenite content of 0.2C-7Mn steel was compared with that of 0.2C-5Mn *** is found that 0.2C-7Mn steel exhibits a similar variation trend of retained austenite content as 0.2C-5Mn ***,in detail,these trends are different.0.2C-7Mn steel contains approximately 7.5vol%retained austenite after austenitization and *** stability of the reversed austenite in 0.2C-7Mn steel is lower than that in 0.2C-5Mn steel;in contrast,the equilibrium reversed austenite fraction of 0.2C-7Mn steel is substantially greater than that of 0.2C-5Mn ***,the retained austenite content in 0.2C-7Mn steel reaches 53.1vol%.The tensile results show that long annealing time and high annealing temperature may not favor the enhancement of mechanical properties of 0.2C-7Mn *** effect of retained austenite on the tensile strength of the steel depends on the content of retained austenite;in contrast,the 0.2%yield strength linearly decreases with increasing retained austenite content.

关键词： manganese steel annealing austenite mechanical properties

Effect of Tempering Temperature on Strength and Toughness of Novel Carbide-Free Bainite/Martensite Duplex Phase Steel

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Journal of Iron and Steel Research International 2002年第1期9卷 46-49页

作者： LIU Dong-yu BAI Bing-zhe FANG hong-sheng YANG Zhi-gang ZHANG chi YAN Wen-yan Tsinghua University

The microstructure in the weld metals for HQ130+QJ63 high strength steels, which are welded by Ar CO 2 gas shielded metal arc welding, was analyzed by means of microscope and scan electron microscope (SEM). The relative content of different microstructure was evaluated with XQF 2000 micro image analyzer. The effect of acicular ferrite content on the impact toughness was also studied. The test results indicated that the main microstructure in the weld metals of HQ130+QJ63 high strength steels is acicular ferrite and a few pro eutectic ferrite on the boundary of original austenite grain. Near the fusion zone there are columnar grains whose direction coefficient (X) is 3 22, but the microstructure in the center of the weld metal is isometric grain, whose direction coefficient X=1 In order to avoid welding crack and improve welding technology the weld heat input should be strictly controlled in 10-16 kJ/cm. Thus, the main microstructure in the weld metals is fine acicular ferrite and the content of pro eutectic ferrite is limited. The impact toughness in the weld metals of HQ130+QJ63 steels can be ensured and can meet the requirements for application in engineering and machinery.

关键词： high strength steel gas shielded metal arc welding weld metal micro image