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二维大片径Ti_(3)C_(2)T_(x)薄膜的制备及其电磁屏蔽性能
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作者 夏斌 喻莉 +5 位作者 罗志娟 王众 周娅玲 杨帆 张剑桥 程诗慧 《功能材料》 北大核心 2026年第2期109-114,共6页
二维Ti_(3)C_(2)T_(x)具有特殊的微观层状结构和良好的物理化学性能,被视为新型高效的电磁屏蔽材料。Ti_(3)C_(2)T_(x)薄膜是通过二维纳米片堆叠制备,因此单个Ti_(3)C_(2)T_(x)纳米片的性能和薄膜中片层排列的有序性都决定了Ti_(3)C_(2)... 二维Ti_(3)C_(2)T_(x)具有特殊的微观层状结构和良好的物理化学性能,被视为新型高效的电磁屏蔽材料。Ti_(3)C_(2)T_(x)薄膜是通过二维纳米片堆叠制备,因此单个Ti_(3)C_(2)T_(x)纳米片的性能和薄膜中片层排列的有序性都决定了Ti_(3)C_(2)T_(x)薄膜的电磁屏蔽性能。基于差速离心的方法,筛选并制备了二维大片径的Ti_(3)C_(2)T_(x)薄膜。利用X射线衍射仪、透射电子显微镜和扫描电子显微镜对Ti_(3)C_(2)T_(x)的化学组成、晶体结构和微观形貌进行表征,利用四探针测试仪和矢量网络分析仪研究了Ti_(3)C_(2)T_(x)的电导率和电磁屏蔽性能。结果表明,大片径Ti_(3)C_(2)T_(x)纳米片在薄膜中呈现规则有序排列,且6μm以上片径Ti_(3)C_(2)T_(x)薄膜的电导率可达1.62×10^(5)S/m,是小片径薄膜的1.5倍,其电磁屏蔽性能最高可达64.8 dB。同时,在薄膜厚度为11μm时具有4.3×10^(6)dB/m的单位厚度电磁屏蔽效能。 展开更多
关键词 二维纳米材料 Ti_(3)C_(2)T_(x) 有序排列 电磁屏蔽 导电性
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NaOH-Na_(2)SO_(3)协同预处理调控桉木孔隙结构及树脂改性性能研究
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作者 覃引鸾 庞小莉 +2 位作者 陈龙海 郑小蓉 龙大军 《森林防火》 2026年第1期137-144,共8页
针对人工林桉树(Eucalyptus spp.)木材密度高、微纤丝角大导致的干燥开裂率高及吸湿膨胀率大等问题,提出分步改性策略:1)采用NaOH—Na_(2)SO_(3)混合溶液预处理优化孔隙结构;2)通过三聚氰胺改性脲醛树脂(MUF)浸渍增强疏水性。以大花序桉... 针对人工林桉树(Eucalyptus spp.)木材密度高、微纤丝角大导致的干燥开裂率高及吸湿膨胀率大等问题,提出分步改性策略:1)采用NaOH—Na_(2)SO_(3)混合溶液预处理优化孔隙结构;2)通过三聚氰胺改性脲醛树脂(MUF)浸渍增强疏水性。以大花序桉(Eucalyptus cloeziana)和尾叶桉(Eucalyptus urophylla)为对象,以及压汞法等方法分析预处理对木材细胞壁孔隙结构、化学成分及树脂浸渍性能的影响。结果表明:3%~5%NaOH与Na_(2)SO_(3)(比例0.83)混合溶液预处理可脱除55%以上木质素,同时抑制纤维素氧化降解,孔隙率提升至50.60%(大花序桉)和42.83%(尾叶桉);树脂改性后木材抗吸水率(WRE)达63.71%,抗膨胀率(ASE)提高至67.42%,尺寸稳定性显著改善。研究揭示了预处理-树脂改性协同作用机制,为速生桉木高值化利用提供了理论支持与技术路径。 展开更多
关键词 桉木 NaOH—Na_(2)SO_(3)预处理 孔隙结构 树脂改性 尺寸稳定性
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元素掺杂及分子吸附对B4C3电子性质的影响
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作者 李萱 邵立 +2 位作者 门彩瑞 何渊淘 李艳 《吉林大学学报(理学版)》 北大核心 2026年第1期158-165,共8页
研究S,N,P,Si 4种原子掺杂和NO,NO_(2),NH_(3),CO,CO_(2),SO_(2),H_(2)S 7种小分子吸附对B_(4)C_(3)二维材料几何结构和电子性质的影响.结果表明,与本征B_(4)C_(3)材料2.020 eV带隙相比,掺杂和小分子吸附体系的禁带宽度均减小.其中,N掺... 研究S,N,P,Si 4种原子掺杂和NO,NO_(2),NH_(3),CO,CO_(2),SO_(2),H_(2)S 7种小分子吸附对B_(4)C_(3)二维材料几何结构和电子性质的影响.结果表明,与本征B_(4)C_(3)材料2.020 eV带隙相比,掺杂和小分子吸附体系的禁带宽度均减小.其中,N掺杂体系的带隙值在4种体系中最小,因此掺杂N原子对B_(4)C_(3)的电子性质影响最明显. NO_(2)吸附后B_(4)C_(3)由半导体变为金属,表明B_(4)C_(3)可有效检测NO_(2)气体. 展开更多
关键词 密度泛函理论 二维B4C3 掺杂 吸附
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面向跨域高光谱图像分类的嵌入Transformer层的轻量型Res-3D-CNN
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作者 杨丽霞 鲍雅君 +1 位作者 张瑞 杨淑媛 《中国图象图形学报》 北大核心 2026年第3期927-943,共17页
目的跨域分类是高光谱图像分类的主要挑战之一。结合域适应与少样本学习的跨域少样本学习(cross domain few shot learning,CDFSL)方法已广泛应用于跨域高光谱图像分类(cross domain hyperspectral image classification,CD-HIC)问题。... 目的跨域分类是高光谱图像分类的主要挑战之一。结合域适应与少样本学习的跨域少样本学习(cross domain few shot learning,CDFSL)方法已广泛应用于跨域高光谱图像分类(cross domain hyperspectral image classification,CD-HIC)问题。由于光谱序列编码的复杂度和类间的光谱相似性,现有的CDFSL方法大多使用卷积神经网络(convolutional neural network,CNN)或其他优秀的空间特征提取器来获取空间信息,以提高分类精度。然而,提取空间特征通常伴随着地面物体分布和类别边界的扭曲。为解决该问题,本文提出了嵌入Transformer层的轻量型Res-3D-CNN(lightweight Res-3D-CNN with Transformer layer embedding,LRCT)作为CD-HIC的特征提取器。LRCT能在提取空间信息的同时获取光谱的长期依赖性,从而显著提高光谱特征方法的判别性能。方法CNN中的卷积(Conv)通过局部感受野的权重共享机制捕捉图像高频特征。而Transformer可通过自注意力机制建模特征间的长程依赖关系,并自适应聚焦关键区域。此外,Transformer表现出低通滤波特性,主要捕获图像的低频全局信息。基于Conv和Transformer的互补特性,将Transformer层嵌入Res-3D-CNN构建轻量型双流特征提取网络,分别对源域和目标域进行特征提取,通过CDFSL框架迁移源域通用特征,实现目标域少样本场景下的高精度分类。结果以Chikusei数据为源域,Indian Pines、Salinas和Pavia University为目标域进行验证。实验结果表明,在每类仅有5个标记样本时,目标域上的总体精度分别达到71.01%、92.06%和84.14%。相较于主流的CDFSL方法,基于LRCT网络的CDFSL(LRCT network based CDFSL,LRCT-CDFSL)方法在各个目标域上均展现出更优的分类性能。结论LRCT-CDFSL结合了残差三维卷积神经网络(residual 3-dimensionl CNN,Res-3D-CNN)、Transformer网络、域适应和少样本学习方法的优势,使CD-HIC精度提升。 展开更多
关键词 高光谱图像分类(HIC) 跨域分类 少样本学习(FSL) 域适应 残差三维卷积神经网络(Res-3D-CNN) TRANSFORMER
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h-BN形状对Si_(3)N_(4)基复合陶瓷的高温摩擦学性能影响研究
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作者 蔺鹏宇 李涛 +5 位作者 宋俊杰 毛宇 章子怡 游鑫 胡丽天 张永胜 《机械工程学报》 北大核心 2026年第1期148-158,共11页
采用热压烧结技术制备出了Si_(3)N_(4)/h-BN自润滑复合材料,并探究了不同形状六方氮化硼对Si_(3)N_(4)/h-BN自润滑复合材料相结构、微观组织、力学性能与高温摩擦性能的影响规律。结果表明:相比于片状六方氮化硼,球状六方氮化硼促进三... 采用热压烧结技术制备出了Si_(3)N_(4)/h-BN自润滑复合材料,并探究了不同形状六方氮化硼对Si_(3)N_(4)/h-BN自润滑复合材料相结构、微观组织、力学性能与高温摩擦性能的影响规律。结果表明:相比于片状六方氮化硼,球状六方氮化硼促进三维连续结构氮化硅基体的形成,使其抗弯强度((369±15.6)MPa)和断裂韧性((5.3±0.78)MPa·m^(1/2))均提高了8%左右。在高温摩擦过程中,磨粒磨损和脆性断裂被认为是Si_(3)N_(4)/h-BN自润滑复合材料的主要磨损机制。当三维结构复合材料(由球状六方氮化硼制备)在800℃下与氮化硅对摩副摩擦时,具有高承载能力的连续氮化硅基体以及自润滑、高热稳定性的致密连续摩擦层的形成,使其比均质结构复合材料(由片状六方氮化硼制备)的摩擦系数降低约23%,磨损率降低近一个数量级。 展开更多
关键词 Si_(3)N_(4)/h-BN自润滑复合材料 三维连续结构 高温 减摩抗磨
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3-Dimensional Irradiance Imaging with a Single Camera System
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作者 陆永刚 王式民 +1 位作者 朱震 徐益谦 《Journal of Southeast University(English Edition)》 EI CAS 1998年第2期40-44,共5页
The focusing tomography is presented to reconstruct 3 dimensional irradiance distribution. A 3 dimensional luminous body could be considered as the combination of many 2 dimensional parallel luminous sections. Focu... The focusing tomography is presented to reconstruct 3 dimensional irradiance distribution. A 3 dimensional luminous body could be considered as the combination of many 2 dimensional parallel luminous sections. Focus on these discrete sections respectively by a single camera, a group of images would be captured to form governing equations of irradiance. After inversion procedure, the irradiance distribution of different sections could be decoded. In this experimentation two lightbulbs are used to simulate two luminous sections. Reasonable results demonstrate that this technique could be a useful method in irradiance reconstruction after further development. 展开更多
关键词 focusing tomography 3 dimensional irradiance reconstruction image
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混合维度CsPbBr_(3)/VO_(2)异质结构的制备及其在光探测中的应用
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作者 陈琴棋 张春阳 +3 位作者 易荣锋 云文磊 苏志城 郭喜涛 《微纳电子技术》 2026年第2期75-84,共10页
全无机钙钛矿CsPbBr_(3)因其优异的光电特性和环境稳定性,近年来在光电探测领域引起了巨大的研究兴趣。然而,受限于CsPbBr_(3)材料的本征光学带隙(~2.2 eV),其光谱响应通常限制在了560 nm以内。在此,采用一个简便的的两步法,即先离心铸... 全无机钙钛矿CsPbBr_(3)因其优异的光电特性和环境稳定性,近年来在光电探测领域引起了巨大的研究兴趣。然而,受限于CsPbBr_(3)材料的本征光学带隙(~2.2 eV),其光谱响应通常限制在了560 nm以内。在此,采用一个简便的的两步法,即先离心铸造后压力辅助热退火,成功地制备了CsPbBr_(3)纳米晶与VO_(2)纳米线(VO_(2) NW)网络的混合维度异质结构(typeⅡ型),利用二者的协调优势,拓宽了CsPbBr_(3)基光电探测器的光谱响应范围。研究结果表明,该异质结构光电探测器对不同光波段包括447、520、637 nm均表现出较好的光电流响应(纳安量级)和较快的响应速度(毫秒量级)。该研究工作为钙钛矿混合维度异质结的构建提供了一种可行的制造方法,也为宽光谱钙钛矿光电器件的实现提供了一种新思路。 展开更多
关键词 CsPbBr_(3) VO_(2)纳米线 离心铸造 压力协助热退火 混合维度异质结构 光电探测器
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3-Dimensional Kinematic Comparison of Arm Movements between an Individual with NGLY1 Deficiency and a Neurotypical Individual
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作者 Charles S. Layne Christopher A. Malaya +6 位作者 Brock Futrell Dacia Martinez Diaz Christian Alfaro Hannah E. Gustafson Subhalakshmi Chandrasekaran Rhea M. Phatak Bernhard Suter 《Case Reports in Clinical Medicine》 2024年第4期122-146,共25页
NGLY1 Deficiency is an ultra-rare autosomal recessively inherited disorder. Characteristic symptoms include among others, developmental delays, movement disorders, liver function abnormalities, seizures, and problems ... NGLY1 Deficiency is an ultra-rare autosomal recessively inherited disorder. Characteristic symptoms include among others, developmental delays, movement disorders, liver function abnormalities, seizures, and problems with tear formation. Movements are hyperkinetic and may include dysmetric, choreo-athetoid, myoclonic and dystonic movement elements. To date, there have been no quantitative reports describing arm movements of individuals with NGLY1 Deficiency. This report provides quantitative information about a series of arm movements performed by an individual with NGLY1 Deficiency and an aged-matched neurotypical participant. Three categories of arm movements were tested: 1) open ended reaches without specific end point targets;2) goal-directed reaches that included grasping an object;3) picking up small objects from a table placed in front of the participants. Arm movement kinematics were obtained with a camera-based motion analysis system and “initiation” and “maintenance” phases were identified for each movement. The combination of the two phases was labeled as a “complete” movement. Three-dimensional analysis techniques were used to quantify the movements and included hand trajectory pathlength, joint motion area, as well as hand trajectory and joint jerk cost. These techniques were required to fully characterize the movements because the NGLY1 individual was unable to perform movements only in the primary plane of progression instead producing motion across all three planes of movement. The individual with NGLY1 Deficiency was unable to pick up objects from a table or effectively complete movements requiring crossing the midline. The successfully completed movements were analyzed using the above techniques and the results of the two participants were compared statistically. Almost all comparisons revealed significant differences between the two participants, with a notable exception of the 3D initiation area as a percentage of the complete movement. The statistical tests of these measures revealed no significant differences between the two participants, possibly suggesting a common underlying motor control strategy. The 3D techniques used in this report effectively characterized arm movements of an individual with NGLY1 deficiency and can be used to provide information to evaluate the effectiveness of genetic, pharmacological, or physical rehabilitation therapies. 展开更多
关键词 NGLY1 Deficiency Developmental Disorders KINEMATICS 3 dimensional Analyses
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Numerical simulation of recalescence of 3-dimensional isothermal solidification for binary alloy using phase-field approach 被引量:8
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作者 朱昌盛 肖荣振 +1 位作者 王智平 冯力 《中国有色金属学会会刊:英文版》 EI CSCD 2009年第5期1286-1293,共8页
A accelerated arithmetic algorithm of the dynamic computing regions was designed,and 3-dimensional numerical simulation of isothermal solidification for a binary alloy was implemented.The dendritic growth and the reca... A accelerated arithmetic algorithm of the dynamic computing regions was designed,and 3-dimensional numerical simulation of isothermal solidification for a binary alloy was implemented.The dendritic growth and the recalescence of Ni-Cu binary alloy during the solidification at different cooling rates were investigated.The effects of cooling rate on dendritic patterns and microsegregation patterns were studied.The computed results indicate that,with the increment of the cooling rate,the dendritic growth velocity increases,both the main branch and side-branches become slender,the secondary dendrite arm spacing becomes smaller,the inadequate solute diffusion in solid aggravates,and the severity of microsegregation ahead of interface aggravates.At a higher cooling rate,the binary alloy presents recalescence;while the cooling rate is small,no recalescence occurs. 展开更多
关键词 二元合金 等温凝固 数值模拟 三维 冷却速度 二次枝晶间距 微观形态 算法设计
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A 3-DIMENSIONAL DATA MODEL FOR VISUALIZING CLOVERLEAF JUNCTION IN A CITY MODEL 被引量:6
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作者 Chen Jun Sun Min Zhou Qiming 《Geo-Spatial Information Science》 1999年第1期9-15,共7页
The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its ma... The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its main body is bestraddle in air,and has aerial intersections between its parts. This complex feature made cloverleaf junction quite different from buildings and terrain, therefore, it is difficult to express this kind of spatial objects in the same way as for buildings and terrain. In this paper,authors analyze spatial characteristics of cloverleaf junction, propose an all-constraint points TIN algorithm to partition cloverleaf junction road surface, and develop a method to visualize cloverleaf junction road surface using TIN. In order to manage cloverleaf junction data efficiently, the authors also analyzed the mechanism of 3DCM data management, extended BLOB type in relational database, and combined R-tree index to manage 3D spatial data. Based on this extension, an appropriate data 展开更多
关键词 3-dimensional CITY model (3DCM) GIS cloverleaf JUNCTION DATA STRUCTURE DATABASE
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Evaluation of Airway Obstruction at Soft Palate Level in Male Patients with Obstructive Sleep Apnea/Hypopnea Syndrome:Dynamic 3-Dimensional CT Imaging of Upper Airway 被引量:10
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作者 肖英 陈雄 +4 位作者 史河水 杨阳 何烈纯 董家琪 孔维佳 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2011年第3期413-418,共6页
This study examined the dynamic characteristics of upper airway collapse at soft palate level in patients with obstructive sleep apnea/hypopnea syndrome(OSAHS) by using dynamic 3-Dimensional(3-D) CT imaging.A tota... This study examined the dynamic characteristics of upper airway collapse at soft palate level in patients with obstructive sleep apnea/hypopnea syndrome(OSAHS) by using dynamic 3-Dimensional(3-D) CT imaging.A total of 41 male patients who presented with 2 of the following symptoms,i.e.,daytime sleepiness and fatigue,frequent snoring,and apnea with witness,were diagnosed as having OSAHS.They underwent full-night polysomnography and then dynamic 3-D CT imaging of the upper airway during quiet breathing and in Muller's maneuver.The soft palate length(SPL),the minimal cross-sectional area of the retropalatal region(mXSA-RP),and the vertical distance from the hard palate to the upper posterior part of the hyoid(hhL) were compared between the two breathing states.These parameters,together with hard palate length(HPL),were also compared between mild/moderate and severe OSAHS groups.Association of these parameters with the severity of OSAHS [as reflected by apnea hypopnea index(AHI) and the lowest saturation of blood oxygen(LSaO2)] was examined.The results showed that 31 patients had severe OSAHS,and 10 mild/moderate OSAHS.All the patients had airway obstruction at soft palate level.mXSA-RP was significantly decreased and SPL remarkably increased during Muller's maneuver as compared with the quiet breathing state.There were no significant differences in these airway parameters(except the position of the hyoid bone) between severe and mild/moderate OSAHS groups.And no significant correlation between these airway parameters and the severity of OSAHS was found.The position of hyoid was lower in the severe OSAHS group than in the mild/moderate OSAHS group.The patients in group with body mass index(BMI)≥26 had higher collapse ratio of mXSA-RP,greater neck circumference and smaller mXSA-RP in the Muller's maneuver than those in group with BMI26(P0.05 for all).It was concluded that dynamic 3-D CT imaging could dynamically show the upper airway changes at soft palate level in OSAHS patients.All the OSAHS patients had airway obstruction of various degrees at soft palate level.But no correlation was observed between the airway change at soft palate level and the severity of OSAHS.The patients in group with BMI≥26 were more likely to develop airway obstruction at soft palate level than those with BMI26. 展开更多
关键词 obstructive sleep apnea/hypopnea syndrome upper airway obstruction soft palate level dynamic computed tomography 3-dimensional imaging
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冷冻电镜揭示长期低温保存的冰冻人血浆中全长补体C3仍可稳定存在
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作者 朱莉 武迪 武一 《电子显微学报》 北大核心 2025年第1期36-43,共8页
补体是血浆中存在的一组重要蛋白质,在机体遭受病原体感染或组织损伤时通过先天免疫途径被激活,发挥抗感染和清除损伤细胞的作用。补体C3是补体系统的核心成分,在三条补体激活途径中均起到至关重要的作用,且在血浆中的含量最为丰富。冰... 补体是血浆中存在的一组重要蛋白质,在机体遭受病原体感染或组织损伤时通过先天免疫途径被激活,发挥抗感染和清除损伤细胞的作用。补体C3是补体系统的核心成分,在三条补体激活途径中均起到至关重要的作用,且在血浆中的含量最为丰富。冰冻人血浆通常由健康志愿者献血后采集,通过迅速冷冻保存制备而成,广泛用于多种医学治疗。然而,关于冰冻人血浆的低温保存条件和时长对补体C3结构完整性的影响尚缺乏准确详细的评估。在本研究中,作者发现,冰冻人血浆在-20℃保存后转为-80℃的条件下保存长达5年,其中的补体C3组分仍能保持完整的结构,且通过冷冻电镜单颗粒重构达到了2.43Å的分辨率,其中ASN63和ASN917上发生的糖基化修饰亦可被解析。与已解析的C3晶体结构相比,RMSD值差异较大区域在α链末端的C345C结构域,与解析的ISG65-C3复合体冷冻电镜结构相比,C3部分的RMSD值差异较大处仅在C345C末端的一段α螺旋。结果表明,在严格的低温保存条件下,尽管保存时间较长,冰冻人血浆中的关键补体组分C3仍能保持结构完整性和稳定性,从而保障其生物学功能的发挥。由此推测,血浆中其他重要的补体组分在类似保存条件和时长下也可维持其天然构象。这一结论为实验室或工业中由冰冻人血浆提纯制备补体各组分蛋白时,对冰冻血浆的保存条件及期限的设定提供了一定的科学依据和参考。 展开更多
关键词 冰冻血浆 补体系统 补体C3 冷冻电镜 三维重构
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NOVEL 6-SPS PARALLEL 3-DIMENSIONAL PLATFORM MANIPULATOR AND ITS FORCE/MOTION TRANSMISSION ANALYSIS 被引量:2
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作者 Jin Zhenlin School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, ChinaGao Feng Hebei University of Technology 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2002年第4期298-302,共5页
The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmissio... The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmission capability, evaluation criteria arepresented. At the orthogonal configuration, the criteria and the relationships between the criteriaand the link lengths are analyzed, which is important since it can provide designer a piece ofvaluable information about how to choose the linear actuators. From the analysis of the results itis shown that the force/motion transmission capabilities of the parallel manipulator arecharacterized by isotropy at the orthogonal configuration. The manipulator is particularly suitablefor certain applications in 6-DOF micromanipulators and 6-axis force/moment transducers. 展开更多
关键词 6-SPS parallel manipulator 3-dimensional platform manipulator ISOTROPY
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Dimensional Synthesis for 3-PRS Mechanism Based on Identifiability Performance 被引量:8
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作者 HUANG Peng WANG Jinsong +1 位作者 WANG Liping QIAN Jie 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第2期234-240,共7页
Many performance indices for parallel mechanism are put forward in the phase of dimensional synthesis,except for identifiability index,which determines the difficulty of kinematical calibration.If the dimensional para... Many performance indices for parallel mechanism are put forward in the phase of dimensional synthesis,except for identifiability index,which determines the difficulty of kinematical calibration.If the dimensional parameters are inappropriately selected,the existing methods for optimizing identifiability will not effectively work.Thus,with the aim of studying identifiability optimization in dimensional synthesis for 3-PRS mechanism,kinematics with structural errors is analyzed to provide theoretical bases for kinematical model.Then through a comparison of two 3-PRS mechanisms with different dimensional parameters,identifiability performance is proved to be necessary and feasible for optimization in the phase of dimensional design.Finally,an index δ is proposed to scale the identifiability performance.With the index,identifiability analysis and dimensional synthesis simulation in the whole workspace is completed.The index is verified to be correct and feasible,and based on the index,a procedure of dimensional synthesis,as well as an example set of non-dimensional parameters of 3-PRS mechanism,is proposed.The proposed identifiability index and design method can effectively introduce identifiability optimization into dimensional synthesis,and will obviously benefit later kinematical calibration. 展开更多
关键词 3-PRS mechanism dimensional synthesis identifiability performance
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The 3-dimensional morphology of dendrite during equiaxed solidification of an Al-5 wt.% Cu alloy 被引量:1
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作者 Xiaoping Ma Dianzhong Li 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2019年第3期239-247,共9页
In a sample quenched during equiaxed solidification of an Al-5 wt.% Cu alloy, the multi-scales 3-dimensional morphology of equiaxed dendrite was observed. The slim primary stem and secondary branches constitute the fr... In a sample quenched during equiaxed solidification of an Al-5 wt.% Cu alloy, the multi-scales 3-dimensional morphology of equiaxed dendrite was observed. The slim primary stem and secondary branches constitute the frame of dendrite, and rows of dense tertiary branches further divide the 3-dimensional space. In the divided space, the quartic branches grow further. The dendritic branches,which are perpendicular to each other, can change their growth directions and coalesce into a whole. In the tertiary branches and quartic branches, the formation of double branch structures is induced by competitive growth. The branch that wins in the competitive growth will produce a cabbage-like structure by wrapping the failed branches. In addition, the side branch can also wrap the original parent branch to produce cabbage-like structures. Depending on the historical growth direction, the dendritic arms can form vein-like and spicate structures, and the shapes of single dendritic arm may be the cylinder, plate and trapezoid platform. According to the compositions and etching morphology, the single dendritic arm in the final solidification structures should coalesce from a fine porous structure. The porous structures at different length-scales are principally induced by the preferential growth. Based on 3-dimensional morphology of equiaxed dendrite, a new research object for the investigation of microsegregation was suggested. 展开更多
关键词 Equiaxed DENDRITE 3-dimensional MORPHOLOGY COMPETITIVE growth COALESCENCE SEGREGATION
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静电纺丝法制备Pr^(3+)掺杂BaTiO_(3)纳米纤维及其光学性能研究 被引量:1
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作者 陈铃 关员路 +4 位作者 刘昊宇 王娇 裴清豪 杨柳 刘少辉 《功能材料》 北大核心 2025年第6期6216-6220,6228,共6页
为了提升钛酸钡材料的发光性能,基于稀土元素掺杂的理念,采用静电纺丝工艺制备出Pr^(3+)掺杂BaTiO_(3)一维纳米纤维,分析了稀土元素Pr掺杂浓度对一维纳米纤维相结构、形貌、发光性能的影响,并对其影响因素及机理进行分析。测试结果表明... 为了提升钛酸钡材料的发光性能,基于稀土元素掺杂的理念,采用静电纺丝工艺制备出Pr^(3+)掺杂BaTiO_(3)一维纳米纤维,分析了稀土元素Pr掺杂浓度对一维纳米纤维相结构、形貌、发光性能的影响,并对其影响因素及机理进行分析。测试结果表明:静电纺丝制备出的Pr^(3+)掺杂BaTiO_(3)纳米粉体具有良好的一维纳米纤维形貌,在较低Pr^(3+)掺杂浓度时,稀土元素Pr^(3+)能够进入BaTiO_(3)粉体的晶格,并不形成新的杂相,荧光性能测试结果表明:Pr^(3+)掺杂可以显著提高BaTiO_(3)一维纳米纤维的发光性能,Pr^(3+)掺杂可以提供相关的电子跃迁能级,荧光峰发射峰位于497、502、539、613、659 nm可以归因于^(3)P_(0)→^(3)H_(4)、^(3)P_(1)→^(3)H_(5)、^(3)P_(0)→^(3)H_(6)、^(3)P_(0)→^(3)F_(2)的能级跃迁,并且随着稀土元素Pr^(3+)掺杂浓度的逐渐增加,Ba 1-x Pr x TiO_(3)一维纳米纤维的荧光发光强度呈现先提高后降低,此现象可以归因于当较低Pr^(3+)浓度掺杂时,BaTiO_(3)晶格与Pr^(3+)间的相互作用,而Pr^(3+)浓度掺杂较高时,BaTiO_(3)晶格内与Pr^(3+)之间的距离变小,导致部分能量转移到猝灭中心,从而导致Pr^(3+)掺杂BaTiO_(3)一维纳米纤维荧光发光强度降低。 展开更多
关键词 BaTiO_(3) 一维纳米纤维 微观形貌 光学性能 Pr^(3+)掺杂 微观机理
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Thermal effect on endurance performance of 3-dimensional RRAM crossbar array 被引量:1
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作者 卢年端 孙鹏霄 +4 位作者 李泠 刘琦 龙世兵 吕杭炳 刘明 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第5期253-257,共5页
Three-dimensional(3D) crossbar array architecture is one of the leading candidates for future ultra-high density nonvolatile memory applications. To realize the technological potential, understanding the reliability... Three-dimensional(3D) crossbar array architecture is one of the leading candidates for future ultra-high density nonvolatile memory applications. To realize the technological potential, understanding the reliability mechanisms of the3 D RRAM array has become a field of intense research. In this work, the endurance performance of the 3D 1D1 R crossbar array under the thermal effect is investigated in terms of numerical simulation. It is revealed that the endurance performance of the 3D 1D1 R array would be seriously deteriorated under thermal effects as the feature size scales down to a relatively small value. A possible method to alleviate the thermal effects is provided and verified by numerical simulation. 展开更多
关键词 3-dimensional resistive random access memory(RRAM) thermal effect endurance performance
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Rota-Baxter Operators on 3-dimensional Lie Algebras and Solutions of the Classical Yang-Baxter Equation 被引量:1
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作者 Cheng Yong-sheng Wu Lin-li +1 位作者 Wang Pan-yin Du Xian-kun 《Communications in Mathematical Research》 CSCD 2019年第1期81-96,共16页
In this paper,we compute Rota-Baxter operators on the 3-dimensional Lie algebra g whose derived algebra’s dimension is 2.Furthermore,we give the corresponding solutions of the classical Yang-Baxter equation in the 6-... In this paper,we compute Rota-Baxter operators on the 3-dimensional Lie algebra g whose derived algebra’s dimension is 2.Furthermore,we give the corresponding solutions of the classical Yang-Baxter equation in the 6-dimensional Lie algebras g ■ _(ad~*) g~* and some new structures of left-symmetric algebra induced from g and its Rota-Baxter operators. 展开更多
关键词 Rota-Baxter OPERATORS 3-dimensional Lie ALGEBRA classical Yang-Baxter equation left-symmetric ALGEBRA
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Intelligent Layout Method of the Powerhouse for Tank & Armored Vehicles Based on 3-Dimensional Rectangular Packing Theory 被引量:1
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作者 王延龙 毛明 +1 位作者 陆一平 别杰民 《Defence Technology(防务技术)》 SCIE EI CAS 2005年第1期17-24,共8页
Probes into a new and effective method in arranging the powerhouses of tank & armored vehicles. Theory and method of 3-dimensional rectangular packing are adapted to arrange effectively almost all the systems and ... Probes into a new and effective method in arranging the powerhouses of tank & armored vehicles. Theory and method of 3-dimensional rectangular packing are adapted to arrange effectively almost all the systems and components in the powerhouse of the vehicle, thus the study can be regarded as an attempt for the theory's engineering applications in the field of tank & armored vehicle design. It is proved that most parts of the solutions attained are reasonable, and some of the solutions are innovative. 展开更多
关键词 智能规划法 坦克装甲 三维矩形装填 电力管理装置
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The role of 3-dimensional ultrasound for the diagnosis of congenital uterine anomalies 被引量:1
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作者 Efraim Zohav Yaakov Melcer +3 位作者 Ilan Tur-Kaspa Jacob Rabinson Eyal Y. Anteby Raoul Orvieto 《Open Journal of Obstetrics and Gynecology》 2011年第4期239-242,共4页
Objectives: To demonstrate the value of 3-dimensional (3-D) ultrasound (US) in the diagnosis of congenital uterine anomalies. Methods: Fifty one infertile patients referred to our US unit during 12 years period, with ... Objectives: To demonstrate the value of 3-dimensional (3-D) ultrasound (US) in the diagnosis of congenital uterine anomalies. Methods: Fifty one infertile patients referred to our US unit during 12 years period, with suspected diagnosis of congenital uterine anomalies by previous HSG or 2D US examinations, were evaluated by transvaginal 3-D US. The 3-D US diagnoses were compared to the initial HSG diagnosis, and to hysteroscopic evaluation when performed. Results: 3-D scan confirmed the initial HSG diagnosis in 27 out of 51 (52.9%) women. The concordancy rates between the initial diagnosis by HSG and 3-D US results were 30.4% for bicornuate uterus;75% for arcuate uterus;83% for septate uterus;and 80% for unicornuate uterus. Of the 13 cases with normal HSG and suspicious 2-D US, 30.8% were found to be normal by 3D sonography. In cases where hysteroscopy was done, the results were 100% in concordance with the 3-D US evaluations. Conclusions: 3-D US is an accurate test for the assessment of uterine congenital anomalies. Its ability to concomitantly visualized, the external uterine contour with the uterine cavity on the same coronal plan, makes this noninvasive, easy to perform test the procedure of choice for the diagnosis of uterine anomalies. 展开更多
关键词 Mullerian ANOMALIES 3-dimensional (3-D) ULTRASONOGRAPHY HYSTEROSALPINGOGRAPHY HYSTEROSCOPY
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