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Sequential therapy for infertility in women with polycystic ovary syndrome and luteal phase defects by Yangxin Dianji decoction(养心奠基方)and Nuangong Tiaojing decoction(暖宫调经方):a real-world study
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作者 JIANG Xiaoyue DING Yinyin +4 位作者 LIU Xinyuan RUAN Fang ZOU Yeting HONG Yanli ZHOU Huifang 《Journal of Traditional Chinese Medicine》 2025年第5期1098-1105,共8页
OBJECTIVE:To evaluate the effectiveness and safety of the sequential therapy in treating infertility with polycystic ovary syndrome(PCOS)and luteal phase defects(LPD)by Yangxin Dianji decoction(养心奠基方,YXDJ-D)and N... OBJECTIVE:To evaluate the effectiveness and safety of the sequential therapy in treating infertility with polycystic ovary syndrome(PCOS)and luteal phase defects(LPD)by Yangxin Dianji decoction(养心奠基方,YXDJ-D)and Nuangong Tiaojing decoction(暖宫调经方,NGTJ-D).METHODS:This study was undertaken in the Jiangsu Province Hospital of Chinese Medicine.Altogether 90 eligible patients with PCOS and LPD were assigned to exposed group A(Chinese Medicine therapy,YXDJ-D and NGTJ-D),exposed group B(Chinese Medicine plus Western Medicine therapy),control group(Western Medicine therapy).The exposed group A adopted the sequential therapy that YXDJ-D is taken in the postmenstrual period(follicular phase)and NGTJ-D is taken in premenstrual period(luteal phase).Control group took letrozole,dydrogesterone and was given intramuscular injection of human menopausal gonadotropin,human chorionic gonadotropin.The exposed group B was treated with the above-mentioned therapy project of integrated Chinese Medicine and Western Medicine.This study lasted for 2 courses for 6 months.The primary outcomes were pregnancy rate and early abortion rate.The secondary outcomes were the Traditional Chinese Medicine(TCM)syndrome scores,estrogen(E2)and progesterone(P),endometrial volume(EV),vascularity index(VI),flow index(FI)and vascularization flow index(VFI).These outcomes will be assessed at baseline and post-intervention.RESULTS:The pregnancy rates of the exposed group A and B were higher than the control group(60.00%vs 60.00%vs 53.33%),while early abortion rates of exposed groups A and B were lower than the control group(33.33%vs 16.67%vs 43.75%,P>0.05).Total efficacy rates in exposed group A and B were better than the control group(93.30%vs 93.30%vs 53.30%,P<0.01).TCM symptom scores and endometrial receptivity indexes(EV,FI,VFI)were significantly lower in exposed groups compared to the control group(P<0.05).P increase in exposed group B was superior to the other two groups(P<0.01).No noticeable abnormalities in safety indicators in the three groups.CONCLUSION:The sequential therapy of YXDJ-D and NGTJ-D can effectively increase pregnancy rate,reduce the early abortion rate and alleviate the clinical symptoms of infertility in patients with PCOS and LPD by improving luteal function and promoting the endometrial receptivity. 展开更多
关键词 INFERTILITY polycystic ovary syndrome luteal phase defect endometrial receptivity Yangxin Dianji decoction Nuangong Tiaojing decoction
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Surface phase defects induced downstream laser intensity modulation in high-power laser facility 被引量:3
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作者 Xin Zhang Wei Zhou +8 位作者 Wanjun Dai Dongxia Hu Xuewei Deng Wanqing Huang Lidan Zhou Qiang Yuan Xiaoxia Huang De'en Wang Ying Yang 《High Power Laser Science and Engineering》 SCIE CAS CSCD 2016年第1期41-44,共4页
Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patter... Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patterns and the optics damage spot distributions from the surface phase defects. Origins are discussed during the processes of optics manufacturing and diagnostics, revealing potential improvements for future optics manufacturing techniques and diagnostic index, which is meaningful for fusion level laser facility construction and its operation safety. 展开更多
关键词 INTENSITY MODULATION optics damage phase defect
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Structural defects in MAX phases and their derivative MXenes:A look forward 被引量:6
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作者 Hui Zhang Tao Hu +1 位作者 Xiaohui Wang Yanchun Zhou 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2020年第3期205-220,共16页
MAX phases and corresponding 2 D derivative MXenes have attracted considerable interests due to not only their fascinating mechanical,physical and chemical properties but also their unique atomically laminated structu... MAX phases and corresponding 2 D derivative MXenes have attracted considerable interests due to not only their fascinating mechanical,physical and chemical properties but also their unique atomically laminated structures.As the most important way to tailor the materials properties,the structural defects in MAX phases and MXenes have been extensively investigated but lack of systematic survey although six reviews and two books in this field have been published.To make the defect-engineering based materials design and exploration more efficient and targeted,this paper provides a review of the recent progress on the nature of different-dimensional structural defects and their influence on the properties,in the hope of facilitating the conversion of established experiment and simulation results into practical guideline for optimizing defects in a broad range of demand-oriented materials development in the future.Also,unsolved issues on the structural defects of these scientifically and technologically important materials are also highlighted for the future study. 展开更多
关键词 CRYSTAL defects Carbides TEM MAX phaseS MXenes
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Fabric Defect Detection Using Independent Component Analysis and Phase Congruency 被引量:7
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作者 LENG Qiujun ZHANG Hu +1 位作者 FAN Cien DENG Dexiang 《Wuhan University Journal of Natural Sciences》 CAS 2014年第4期328-334,共7页
A novel method based on independent component analysis and phase congruency is proposed for detecting defects in textile fabric images. By independent component, we can obtain textile structural features of fabric-fre... A novel method based on independent component analysis and phase congruency is proposed for detecting defects in textile fabric images. By independent component, we can obtain textile structural features of fabric-free images. By phase congru- ency, structure information is reduced, which can distinguish the defect region from the defect-free regions. Finally, we have the detecting result from binary image which is obtained by a thresh- old step, Compared with other algorithms, the proposed method not only has robustness with high detection rate, but also detects various types of defects quite well. 展开更多
关键词 fabric defect detection independent componentanalysis phase congruency morphological filter
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Study of Dielectric and Mechanical Spectra on Point Defects and Phase Transition in Ferroelectric Ceramics
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作者 ZHU J S LI W +2 位作者 CHEN K LU X M WANG Y N 《四川大学学报(自然科学版)》 CAS CSCD 北大核心 2005年第S1期18-18,共1页
Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are ... Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are very sensitive to phase transitions, relaxation process of point defects, domain walls and their mobility, which have severe effect on ferroelectric properties. These make them become very good means to investigate substantial information on structural features and to explore the fundamental principles in ferroelectric materials and their applications. In this paper, the dielectric and internal friction measurement were used to investigate the behaviors for point defects and phase transition in ferroelectric ceramics such as Bi_ 4-x La_ x Ti_ 3 O_ 12 , Bi_ 4 Ti_ 3-y Nb_ y O_ 12 , SrBi_ 2 Ti_ 2 O_ 9 , PbZr_ x Ti_ 1-x O_ 3 ,_ PMN-PT. They were used to clarify the mechanism for some ferroelectric behaviors. 展开更多
关键词 Dielectric and mechanic spectra Ferroelectric ceramics Point defects and phase transition.
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A Molecular Dynamics Study on the Effects of Lattice Defects on the Phase Transformation from BCC to FCC Structures
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作者 Takuya Uehara 《Materials Sciences and Applications》 2019年第8期543-557,共15页
Molecular dynamics simulations of the phase transformation from body- centered-cubic (bcc) to face-centered-cubic (fcc) structures were performed. A Morse-type function was applied, and the parameters were determined ... Molecular dynamics simulations of the phase transformation from body- centered-cubic (bcc) to face-centered-cubic (fcc) structures were performed. A Morse-type function was applied, and the parameters were determined so that both fcc and bcc structures were stable for the perfectcrystal model. When the fcc structure was superior to the bcc structure, the bcc model transformed to fcc. Two mechanisms, based on the Bain and Nishiyama- Wasserman (NW) relationships, were considered. Then, point or linear lattice defects, i.e., randomly scattered or regularly aligned vacancies, were introduced. Consequently, bcc models tended to transform to an fcc structure, whereas fcc models remained stable. The transformation process was also investigated in detail. BCC-to-FCC transformation is often considered as a homogeneous process based on changes in the axis lengths, and such a process was observed for the perfectcrystal model. Conversely, for the defect models, local heterogeneous deformation patterns, including cylindrical domain and planar interface formation, were observed. These behaviors are considered to be related to plastic deformation during phase transformation, and the validity of the presented model for further investigation was confirmed. 展开更多
关键词 Molecular Dynamics phase TRANSFORMATION LATTICE defect Plastic Deformation TRANSFORMATION PLASTICITY
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孔洞缺陷对α-Fe拉伸变形行为影响的分子动力学模拟
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作者 李翔 尹益辉 +2 位作者 张元章 李继承 李洪祥 《稀有金属材料与工程》 北大核心 2026年第2期510-516,共7页
为深入研究孔洞缺陷对α-Fe试样拉伸变形行为的影响,构建含不同大小孔洞缺陷的α-Fe试样计算模型,并进行单轴拉伸应变下的分子动力学模拟。结果表明:整体趋势上,含孔洞缺陷试样的拉伸力学性能损减与孔洞尺寸正相关,孔洞尺寸越大,试样越... 为深入研究孔洞缺陷对α-Fe试样拉伸变形行为的影响,构建含不同大小孔洞缺陷的α-Fe试样计算模型,并进行单轴拉伸应变下的分子动力学模拟。结果表明:整体趋势上,含孔洞缺陷试样的拉伸力学性能损减与孔洞尺寸正相关,孔洞尺寸越大,试样越容易进入塑性变形阶段;含孔洞缺陷试样的杨氏模量、屈服应力、极限强度和拉断延伸率均随着孔洞半径的增大而减小;试样的塑性变形表现为拉伸应力诱发的相变和位错滑移混合的机制;随着孔洞半径的增大,试样的应力-应变曲线特征发生显著变化——试样的塑性屈服段和应变硬化段越来越短,应变硬化段甚至消失。研究有助于深入认识孔洞缺陷对金属变形机制的影响,为后续开展多晶α-Fe材料的物理和力学性质的分析研究奠定有益基础。 展开更多
关键词 Α-FE 孔洞 相变 位错滑移
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TA15钛合金激光增材制造缺陷预制及相控阵超声检测
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作者 何振丰 赵吉宾 +3 位作者 赵宇辉 王志国 史小全 贺晨 《电加工与模具》 北大核心 2026年第1期70-75,共6页
采用激光增材制造技术,分别通过增大扫描间距及预埋陶瓷球预制了含有熔合不良缺陷及夹杂缺陷的TA15钛合金样件,采用相控阵超声检测技术分别从X(扫描方向)、Y(步进方向)、Z(沉积方向)三个方向对预制缺陷的超声检测特性进行了研究,并利用... 采用激光增材制造技术,分别通过增大扫描间距及预埋陶瓷球预制了含有熔合不良缺陷及夹杂缺陷的TA15钛合金样件,采用相控阵超声检测技术分别从X(扫描方向)、Y(步进方向)、Z(沉积方向)三个方向对预制缺陷的超声检测特性进行了研究,并利用宏观金相分析对超声检测结果进行了验证。研究结果表明,预制的熔合不良缺陷为面状缺陷,仅能从X方向检测到,而预制的夹杂缺陷从三个方向皆能检测到,但是从Z方向检测时缺陷的超声反射波幅最大,缺陷更容易被检测到。这说明不同类型的增材缺陷具有不同的形状及分布特征,从不同方向进行超声检测时的缺陷评定结果可能会产生差异。 展开更多
关键词 激光增材制造 钛合金 缺陷预制 相控阵超声检测 检测方向
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双金属离子掺杂调控准二维钙钛矿薄膜光学性质
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作者 季思航 胡言松 +1 位作者 张婉怡 袁曦 《半导体光电》 北大核心 2026年第1期116-123,共8页
准二维铅卤钙钛矿薄膜(A_(2)B_(n-1)Pb_(n)Br_(3n+1))具有发光线宽窄、激子束缚能高和载流子扩散寿命长等优势,但该材料在发光效率和光稳定性方面仍存在不足,在多种实际应用场景中仍然面临挑战。为此,文章提出一种双金属协同掺杂策略,... 准二维铅卤钙钛矿薄膜(A_(2)B_(n-1)Pb_(n)Br_(3n+1))具有发光线宽窄、激子束缚能高和载流子扩散寿命长等优势,但该材料在发光效率和光稳定性方面仍存在不足,在多种实际应用场景中仍然面临挑战。为此,文章提出一种双金属协同掺杂策略,以增强薄膜的光量子产率。通过在准二维锌钛矿(BA_(2)MA_(n-1)Pb_(n)Br_(3n+1))薄膜中共掺杂Cs^(+)和Cd^(2+)离子,显著优化了薄膜的光学性能和相稳定性。X射线衍射证实了准二维钙钛矿的结构演变,层数从n=1增加至n>3。扫描电子显微镜展示出掺杂薄膜的平坦形貌、表面针孔被有效修饰。X射线光电子能谱特征峰证明,Cs^(+)和Cd^(2+)离子被有效掺杂到晶格。光谱分析表明,一价Cs^(+)离子掺杂会迫使准二维钙钛矿层数增加,导致使激子发光峰红移,而二价Cd^(2+)离子掺杂会引起晶格收缩,导致激子发光蓝移。将这两种金属离子引入晶格后,有效钝化了薄膜的能级缺陷态,延长了带边的复合寿命,进而提高了薄膜量子产率至85%。此外,Cs^(+)和Cd^(2+)离子的协同作用改善了薄膜的相稳定性,在12 h后仍能维持高质量发光。 展开更多
关键词 准二维钙钛矿薄膜 金属离子掺杂 缺陷态 光致发光 相稳定性
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超声相控阵缺陷表征方法研究现状
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作者 林立志 王晓 +3 位作者 郭昌荣 胡义亮 叶涛 白龙 《测控技术》 2026年第1期1-12,共12页
超声相控阵无损检测技术作为现代无损检测的重要手段,在核电、航空航天等高端装备制造领域关键部件的质量检测中发挥着不可替代的作用,为重大工程结构的运行安全提供了可靠保障。其中,缺陷表征技术是实现超声检测从定性判断到定量分析... 超声相控阵无损检测技术作为现代无损检测的重要手段,在核电、航空航天等高端装备制造领域关键部件的质量检测中发挥着不可替代的作用,为重大工程结构的运行安全提供了可靠保障。其中,缺陷表征技术是实现超声检测从定性判断到定量分析的跨越的核心环节,其准确度直接关系到缺陷危害性评估的可靠性和结构剩余寿命预测的精确性,具有重大的工程应用价值和社会经济效益。近年来,国内外学者在该领域开展了大量卓有成效的研究工作,从信号处理、图像重建、缺陷参数反演等多个维度为工业应用提供了坚实的理论基础。系统地梳理了超声相控阵缺陷表征技术的研究进展,重点评述了关键技术的发展现状,并针对当前研究瓶颈对未来发展方向进行了前瞻性展望。 展开更多
关键词 超声相控阵 缺陷表征 信号处理 图像重建 参数反演
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重氮盐化学构筑量子缺陷:碳纳米管的高效共价功能化
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作者 赵雨晴 尹太山 黄中杰 《材料导报》 北大核心 2026年第5期136-141,共6页
作为一维量子材料,单壁碳纳米管具有独特的电学和光学性能。通过在半导体单壁碳纳米管的sp^(2)晶格中合成sp^(3)缺陷,可将传统晶体里不受欢迎的缺陷变成调配低维材料中电子、激子、声子和自旋耦合的分子焦点。这类量子缺陷在室温单光子... 作为一维量子材料,单壁碳纳米管具有独特的电学和光学性能。通过在半导体单壁碳纳米管的sp^(2)晶格中合成sp^(3)缺陷,可将传统晶体里不受欢迎的缺陷变成调配低维材料中电子、激子、声子和自旋耦合的分子焦点。这类量子缺陷在室温单光子源、近红外二区生物成像、化学传感等领域有广阔的应用前景。然而目前的合成研究大多局限于溶液体系,对于许多光电子器件、光子系统和量子网络等应用中所需的固态薄膜上的合成研究较少。本工作围绕碳纳米管的成膜制备、膜上原位缺陷合成和表征三个核心环节展开研究,利用碘化钾还原芳基重氮盐对碳纳米管进行功能化修饰,通过系统地调控反应时间、反应物浓度,得到规律性的功能化效果。功能化方法操作简单,快捷高效,且无需施加光、电、热等其他条件。拉曼光谱D峰的增强以及荧光光谱中出现的新的发光峰都证实了量子缺陷合成的成功。本研究成功实现了在薄膜上合成量子缺陷,为进一步拓展其在生物成像、传感器和量子技术等领域的应用做出贡献。 展开更多
关键词 单壁碳纳米管(SWCNTs) 重氮化学 量子缺陷 固相体系
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基于CIVA仿真的蓄能机组顶盖管路焊缝相控阵探头优化
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作者 王磊 赵亮 薛贺文 《电机技术》 2026年第1期37-42,共6页
为优化蓄能机组顶盖部件内管路焊缝的相控阵超声检测探头性能,对不同频率的相控阵超声检测探头进行CIVA声场仿真,并通过根部未焊透、根部未熔合、坡口未熔合、坡口裂纹和焊缝中心气孔、夹渣等典型缺陷的模拟响应,明确了相控阵超声检测... 为优化蓄能机组顶盖部件内管路焊缝的相控阵超声检测探头性能,对不同频率的相控阵超声检测探头进行CIVA声场仿真,并通过根部未焊透、根部未熔合、坡口未熔合、坡口裂纹和焊缝中心气孔、夹渣等典型缺陷的模拟响应,明确了相控阵超声检测探头优化的方向,可为实际检测时相控阵超声检测探头参数的选取和检测工艺的制定提供依据。 展开更多
关键词 相控阵超声检测 CIVA仿真 典型缺陷 探头优化
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图注意力网络下的高压架空输电线路缺陷识别
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作者 李甜甜 张清峰 +1 位作者 景川 余波 《电子设计工程》 2026年第4期103-108,共6页
针对高压架空输电线路传统巡检方式效率低、检测精度低的问题,提出一种基于改进图注意力网络的高压架空输电线路缺陷识别方法。通过动态裁剪冗余边连接降低模型复杂度,采用点乘运算替代传统注意力权重计算,优化模型对邻域特征的聚合能... 针对高压架空输电线路传统巡检方式效率低、检测精度低的问题,提出一种基于改进图注意力网络的高压架空输电线路缺陷识别方法。通过动态裁剪冗余边连接降低模型复杂度,采用点乘运算替代传统注意力权重计算,优化模型对邻域特征的聚合能力。结果表明,改进模型的训练效率较原始模型提升3倍;当训练数据规模超过1 000时,模型准确率稳定在95%以上,对测试集主要缺陷类别的识别准确率超过85%。该方法显著提高了缺陷检测的鲁棒性与实时性,为复杂电网结构的智能巡检提供了有效的解决方案。 展开更多
关键词 图注意力网络 输电线路 缺陷识别 阶段性丢边机制
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基于相位测量偏折术的高反光表面多通道缺陷检测
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作者 明昊 宋伟 +1 位作者 陈皓 罗印升 《工业控制计算机》 2026年第2期134-136,共3页
针对我国电池外壳材料表面高反光导致缺陷难以检测的问题,提出了一种基于相位测量偏折术的精确成像方法。该方法利用LCD屏幕投射优化后的正弦条纹,通过四步相移法生成不同频率、方向和周期的条纹,并使用相机捕捉物体表面反射的条纹图案... 针对我国电池外壳材料表面高反光导致缺陷难以检测的问题,提出了一种基于相位测量偏折术的精确成像方法。该方法利用LCD屏幕投射优化后的正弦条纹,通过四步相移法生成不同频率、方向和周期的条纹,并使用相机捕捉物体表面反射的条纹图案。通过时间相位展开法处理条纹图案,重建反射率和梯度信息,将缺陷相位信息转化为可视化的缺陷图案,并通过多通道对比确定缺陷类型。实验证明,该方法能有效检测铝壳表面的划痕、凹点和脏污等缺陷,满足高反光表面检测需求。 展开更多
关键词 相位测量偏折术 四步相移法 条纹优化 缺陷检测
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Ultrasonic flaw detection of discontinuous defects in magnesium alloy materials 被引量:6
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作者 Sheng-nan Xue Qi-chi Le +3 位作者 Yong-hui Jia Li-ping Jiang Zhi-qiang Zhang Lei Bao 《China Foundry》 SCIE 2019年第4期256-261,共6页
Phased array ultrasonic testing, an effective ultrasonic testing(UT) technology, has been widely used in steel inspection because of its high accuracy, sensitivity, and efficiency. However, as its application in as-ca... Phased array ultrasonic testing, an effective ultrasonic testing(UT) technology, has been widely used in steel inspection because of its high accuracy, sensitivity, and efficiency. However, as its application in as-cast magnesium alloys has just begun, more research is needed. Considering the important role of the gain compensation in quantifying defects in magnesium alloys by ultrasonic phased array technology, the effects of microstructure, the position, size, and overlap of defects, and boundary distance(distance from the defect position to the side surface of the test casting) on gain compensation of as-cast AZ80 and AZ31 magnesium alloys were studied. Results show the gain compensation increases with the increase of grain size. There is a strict linear positive correlation between gain compensation and defect depth, but such relationship no longer exists due to the defects overlap, orientation and boundary distance. In addition, there is a strict linear negative correlation between the gain compensation and defect size. 展开更多
关键词 MAGNESIUM alloy ULTRASONIC phased array defect detection GAIN COMPENSATION
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基于超声相控无损检测的破裂岩石内部缺陷定位与重构
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作者 黄耀光 刘英俊 +1 位作者 崔正 何安林 《科学技术与工程》 北大核心 2026年第2期465-475,共11页
为实现对岩石内部缺陷的超声相控无损检测,完成缺陷定位与注浆效果评价,通过超声相控理论、首波幅值点定位理论和有限元数值模拟方法,构建含有内部孔洞缺陷的数值模型。研究了不同孔径下超声波速起跳时间和超声波声压特征,提出了一种基... 为实现对岩石内部缺陷的超声相控无损检测,完成缺陷定位与注浆效果评价,通过超声相控理论、首波幅值点定位理论和有限元数值模拟方法,构建含有内部孔洞缺陷的数值模型。研究了不同孔径下超声波速起跳时间和超声波声压特征,提出了一种基于超声相控阵注浆体缺陷定位方法及重构模型,弥补了相控超声波在岩石缺陷定位方面的不足,结果表明:孔洞缺陷位置不变时,缺陷回波不变,孔径越大,声波声速和声压幅值越大。缺陷横向与纵向定位相对误差均小于5%。底部回波能有效验证定位方法。形状重构相似率能有效定量评价缺陷形状重构。可见该方法能根据回波信号有效检测破裂岩石内部缺陷并进行缺陷形状重构。 展开更多
关键词 超声相控 无损检测 首波幅值 超声特征 缺陷定位 形状重构
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Prediction of shear-related defect locations in semi-solid casting using numerical flow models 被引量:1
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作者 F.PINEAU G.D'AMOURS 《中国有色金属学会会刊:英文版》 CSCD 2010年第S3期878-882,共5页
Contaminated surfaces of the feedstock materials in aluminum alloy casting processes often produce various types of defects which can affect the tensile properties of the final products as well as their fatigue reliab... Contaminated surfaces of the feedstock materials in aluminum alloy casting processes often produce various types of defects which can affect the tensile properties of the final products as well as their fatigue reliabilities.Semi-solid processing takes advantage of a much higher apparent viscosity of the die cast materials by limiting the risk of oxides formed at the free surfaces to become incorporated into the casting when the material is injected into the die.Most of existing semi-solid processes that use billets as feedstock material are however tied up with a different type of contaminated surface.During the injection phase,the external-skin on the periphery of the billet,which has been in contact with air and lubricant during the transfer in the shot sleeve,can be incorporated into the casting.When subjected to a heat treatment,the lubricant is decomposed and produces lens shape porosities.This might be a cause of reject for most structural parts.To avoid this kind of defects,the paths along which the billet skin evolves must be controlled during filling.In order to investigate the possibility of skin inclusion into cast parts during injection of the billet,a two-phase finite element mixture model is employed to model the metal flow.The formation of a skin on the periphery of the billet is modeled by setting an initial solid phase concentration profile in the radial direction.Microscopic observations of the real castings show that the approach is able to model the shear layers and to predict the paths along which the"lens porosity"defects could be formed.An Arbitrary Eulerian-Lagangian(ALE) method is also investigated and appears to be very promising to follow the skin movement in the casting. 展开更多
关键词 oxide SKIN defects TWO-phase flow finite element modeling ARBITRARY Eulerian-Lagangian(ALE) method
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Resonant Modes of One-Dimensional Metamaterial Containing Helmholtz Resonators with Point Defect 被引量:1
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作者 Dongbao Gao Xinwu Zeng +1 位作者 Xuanjun Liu Kaifeng Han 《Journal of Modern Physics》 2017年第10期1737-1747,共11页
The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-... The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-dimensional HR structure with point defect were studied using finite element method (FEM). The results show that the acoustic energy is localized between the resonant HR and the opening in the local-resonant-type gap. There is a high pressure area around the defect resonator at the frequency of defect mode. In the Bragg type gap, the energy mainly distributes in the waveguide with harmonic attenuation due to the multi-scattering. Phase opposition demonstrates the existence of negative dynamic mass density. Local negative parameter is observed in the pass band due to the defect mode. Based on further investigation of the acoustic intensity and phase distributions in the resonators corresponding to two different forbidden bands, only one local resonant mode is verified, which is different from the three-component local resonant phononics. This work will be useful for understanding the mechanisms of acoustic forbidden bands and negative parameters in the HR metamaterial, and of help for designing new functional acoustic devices. 展开更多
关键词 HELMHOLTZ RESONATOR METAMATERIAL RESONANT Mode Point defect Local NEGATIVE Parameters phase Distribution
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Dynamic Two-phase Truncated Rayleigh Model for Release Date Prediction of Software
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作者 Lianfen Qian Qingchuan Yao Taghi M. Khoshgoftaar 《Journal of Software Engineering and Applications》 2010年第6期603-609,共7页
Software reliability modeling and prediction are important issues during software development, especially when one has to reach a desired reliability prior to software release. Various techniques, both static and dyna... Software reliability modeling and prediction are important issues during software development, especially when one has to reach a desired reliability prior to software release. Various techniques, both static and dynamic, are used for reliability modeling and prediction in the context of software risk management. The single-phase Rayleigh model is a dynamic reliability model;however, it is not suitable for software release date prediction. We propose a new multi-phase truncated Rayleigh model and obtain parameter estimation using the nonlinear least squares method. The proposed model has been successfully tested in a large software company for several software projects. It is shown that the two-phase truncated Rayleigh model outperforms the traditional single-phase Rayleigh model in modeling weekly software defect arrival data. The model is useful for project management in planning release times and defect management. 展开更多
关键词 SOFTWARE Testing WEEKLY defect Arrival Data Single-phase RAYLEIGH MODEL TWO-phase TRUNCATED RAYLEIGH MODEL SOFTWARE Reliability
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应用正电子湮没谱学研究CaO添加对Al_(2)O_(3)纳米陶瓷烧结过程的影响 被引量:3
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作者 杨炫烨 赵文增 +2 位作者 张思敏 文海懿 吴奕初 《核技术》 北大核心 2025年第2期34-43,共10页
利用对原子尺度缺陷特别灵敏的正电子湮没谱学技术,并结合X射线衍射(X-ray Diffraction,XRD)、扫描电子显微镜(Scanning Electron Microscopy,SEM)等表征手段,研究了少量氧化钙添加量对氧化铝纳米陶瓷烧结过程中的微观缺陷、物相和显微... 利用对原子尺度缺陷特别灵敏的正电子湮没谱学技术,并结合X射线衍射(X-ray Diffraction,XRD)、扫描电子显微镜(Scanning Electron Microscopy,SEM)等表征手段,研究了少量氧化钙添加量对氧化铝纳米陶瓷烧结过程中的微观缺陷、物相和显微形貌的影响。XRD及SEM实验结果表明,CaO/Al_(2)O_(3)纳米陶瓷的烧结过程可以分为两个阶段:室温至900℃未发生相变,而900~1100℃发生明显相变。少量Ca O的添加(如1%质量分数)起初均匀地分布在Al_(2)O_(3)中,随着烧结温度升高将与Al_(2)O_(3)反应形成第二相并在高温下转变为液相,传质机理由固相扩散变成液相流动,可以降低烧结温度,延缓γ-Al_(2)O_(3)纳米陶瓷转变为α-Al_(2)O_(3)过程,在1100℃烧结后出现不同网状结构的板片状结构。正电子湮没寿命谱分析表明,相变前后Ca O/Al_(2)O_(3)纳米陶瓷中的空位团和微孔洞的大小及数量随烧结温度的变化规律与Al_(2)O_(3)纳米陶瓷不同,由于第二相的形成并在高温下转变为液相,导致CaO/Al_(2)O_(3)纳米陶瓷中更容易产生空位团及微孔洞,并且一部分微孔洞相变前会逐渐合并形成宏观孔洞,而Al_(2)O_(3)纳米陶瓷内的微孔洞则会随着相转变及晶粒生长而消失,仅在样品表面还存留微量的微孔洞。 展开更多
关键词 正电子湮没 氧化铝/氧化钙 相变 缺陷
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