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长方体ΔT场及其梯度场无解析奇点理论表达式 被引量:62
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作者 郭志宏 管志宁 熊盛青 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2004年第6期1131-1138,共8页
首次明确指出文献中长方体ΔT场及其梯度场理论表达式在上半无源空间存在某些点的场值无法计算的解析“奇点”问题 .通过详细的理论推导 ,深入分析了出现解析“奇点”的原因 ,并在此基础上导出新的长方体ΔT场及其梯度场在上半无源空间... 首次明确指出文献中长方体ΔT场及其梯度场理论表达式在上半无源空间存在某些点的场值无法计算的解析“奇点”问题 .通过详细的理论推导 ,深入分析了出现解析“奇点”的原因 ,并在此基础上导出新的长方体ΔT场及其梯度场在上半无源空间无解析“奇点”的理论表达式 .对比模型正演计算结果表明 ,新导出的ΔT场及其梯度场无解析“奇点” 展开更多
关键词 长方体 △T场 梯度场 解析“奇点” 航空磁测
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长方体磁场及其梯度无解析奇点表达式理论研究 被引量:19
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作者 骆遥 姚长利 《石油地球物理勘探》 EI CSCD 北大核心 2007年第6期714-719,共6页
本文在分析郭志宏等人提出的长方体ΔT场及其梯度场理论表达式在上半无源空间存在某些点的场值无法计算的解析"奇点"问题基础上,首次引入欧拉方程对长方体磁场理论表达式进行重新推导,导出了新的长方体ΔT场及其梯度场在上半... 本文在分析郭志宏等人提出的长方体ΔT场及其梯度场理论表达式在上半无源空间存在某些点的场值无法计算的解析"奇点"问题基础上,首次引入欧拉方程对长方体磁场理论表达式进行重新推导,导出了新的长方体ΔT场及其梯度场在上半无源空间的无解析"奇点"理论表达式。该表达式不仅具有形式简单、统一,计算量小等优点,而且具有重要的理论和实际意义。对比模型正演计算结果表明,新导出的ΔT场及其梯度场无解析"奇点"理论表达式是正确的。 展开更多
关键词 长方体 磁场 梯度 欧拉方程 解析“奇点”
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长方体劈裂试验的可行性研究 被引量:5
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作者 刘勇军 朱岳明 +1 位作者 曹为民 沈洪俊 《河海大学学报(自然科学版)》 CAS CSCD 北大核心 2001年第5期100-102,共3页
分析了长方体劈裂试验的可行性 ,得到了抗拉强度值和试件尺寸的关系 ,并且找到了可替代巴西试验的长方体宽高比范围 ,对各种宽高比所得的拉应力值进行误差分析和优劣对比 。
关键词 长方体 抗拉强度 劈裂试验 可行性
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Controlled fabrication, lasing behavior and excitonic recombination dynamics in single crystal CH3NH3PbBr3 perovskite cuboids 被引量:5
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作者 Fangtao Li Junfeng Lu +7 位作者 Qinglin Zhang Dengfeng Peng Zheng Yang Qian Xu Caofeng Pan Anlian Pan Tianfeng Li Rongming Wang 《Science Bulletin》 SCIE EI CAS CSCD 2019年第10期698-704,共7页
As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. T... As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices. 展开更多
关键词 Lead HALIDE PEROVSKITE SOLVOTHERMAL method Single crystal cuboid LASING TRPL
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2.5D地质体重磁异常无解析奇点正演计算研究 被引量:6
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作者 骆遥 姚长利 +1 位作者 薛典军 金玉洁 《石油地球物理勘探》 EI CSCD 北大核心 2009年第4期487-493,共7页
本文明确指出现有文献中有关2.5D重磁异常正演模型在上半无源空间存在某些点的场值无法计算的解析"奇点"问题,长方体ΔT场及其梯度场正演计算理论表达式在上半无源空间存在场值无法计算的解析"奇点"问题仅是2.5D体... 本文明确指出现有文献中有关2.5D重磁异常正演模型在上半无源空间存在某些点的场值无法计算的解析"奇点"问题,长方体ΔT场及其梯度场正演计算理论表达式在上半无源空间存在场值无法计算的解析"奇点"问题仅是2.5D体的一种特例情况。通过详尽的理论推导,建立了2.5D体重磁异常在上半无源空间无解析"奇点"正演计算模型,并在此基础上导出了新的长方体ΔT场在上半无源空间无解析奇点理论表达式。上述建立的模型或表达式是普遍适用的,同现有模型或表达式相比,具有形式统一、正演计算快速的优点,一定程度上满足了正反演中快速计算的需求。对比计算表明,所建立的2.5D体重磁异常无解析"奇点"正演计算模型和新导出的ΔT场无解析"奇点"理论表达式是正确的。 展开更多
关键词 2.5D体 重磁异常 正演 解析“奇点” 长方体
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Projections between Euclidean Volumes with Information Due to Spontaneous Symmetry Breaking
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作者 Louis M. Houston 《Journal of Applied Mathematics and Physics》 2023年第11期3519-3528,共10页
The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternativ... The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternative method for the illustration of multi-dimensional spaces. That was developed with a unique series that gives structure to integer exponents of power sets. The desired coupling is concisely illustrated in a single figure which includes three cyclic phases that are isomorphic to the three phases of Euclidian, rectangular cuboids. The series enables projections between n- and m-dimensional volumes. The associated figure also illustrates how vertical and/or horizontal symmetry breaking or symmetry emits or absorbs information. 展开更多
关键词 ENTROPY SYMMETRY BIT MULTI-DIMENSIONAL cuboid
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Experimental study of settling and drag on cuboids with square base 被引量:3
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作者 Jinsheng Wang Haiying Qi Junzong Zhu 《Particuology》 SCIE EI CAS CSCD 2011年第3期298-305,共8页
The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such pa... The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear. 展开更多
关键词 cuboid particles Unsteady settling behavior Archimedes number Terminal velocity Drag coefficient
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PrefixCube计算的优化 被引量:3
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作者 冯玉才 方琼 +1 位作者 李曲 冯剑琳 《计算机科学》 CSCD 北大核心 2004年第12期81-85,96,共6页
基本单元组浓缩把那些由同一条基表元组聚集计算得到的立方元组浓缩成一条,从而减小数据立方的体积。共享前缀技术通过消除元组之间的前缀冗余来进一步压缩数据立方。PrefixCube就是将基本单元组的浓缩与共享前缀结合,而提出的一种有效... 基本单元组浓缩把那些由同一条基表元组聚集计算得到的立方元组浓缩成一条,从而减小数据立方的体积。共享前缀技术通过消除元组之间的前缀冗余来进一步压缩数据立方。PrefixCube就是将基本单元组的浓缩与共享前缀结合,而提出的一种有效的数据立方组织形式。在本文中,我们以批处理模式进一步优化计算PrefixCube,从而减少PrefixCube的计算时间代价。通过在模拟数据集和真实数据集上的实验证明,在大多数数据集上,以批处理模式计算PrefixCube要优于一般模式计算PrefixCube。 展开更多
关键词 数据立方 元组 批处理 数据集 共享 冗余 模拟数据 小数 一般模式 实数
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Finite size specimens with cracks of icosahedral Al Pd Mn quasicrystals 被引量:2
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作者 杨连枝 Ricoeur Andreas +1 位作者 何蕃民 高阳 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第5期404-413,共10页
Icosahedral quasicrystals are the most important and thermodynamically stable in all about 200 kinds of quasicrystals currently observed. Beyond the scope of classical elasticity, apart from a phonon displacement fiel... Icosahedral quasicrystals are the most important and thermodynamically stable in all about 200 kinds of quasicrystals currently observed. Beyond the scope of classical elasticity, apart from a phonon displacement field, there is a phason displacement field in the elasticity of the quasicrystal, which induces an important effect on the mechanical properties of the material and makes an analytical solution difficult to obtain. In this paper, a finite element algorithm for the static elasticity of icosahedral quasicrystals is developed by transforming the elastic boundary value problem of the icosahedral quasicrystals into an equivalent variational problem. Analytical and numerical solutions for an icosahedral A1-Pd-Mn quasicrystal cuboid subjected to a uniaxial tension with different phonon-phason coupling parameters are given to verify the validity of the numerical approach. A comparison between the analytical and numerical solutions of the specimen demonstrates the accuracy and efficiency of the present algorithm. Finally, in order to reveal the fracture behavior of the icosahedral A1-Pd-Mn quasicrystal, a cracked specimen with a finite size of matter is investigated, both with and without phonon-phason coupling. Meanwhile, the geometry factors are calculated, including the stress intensity factor and the crack opening displacement for the finite-size specimen. Computational results reveal the importance of pbonon-phason coupling effect on the icosahedral A1-Pd-Mn quasicrystal. Furthermore, the finite element procedure can be used to solve more complicated boundary value problems. 展开更多
关键词 icosahedral quasicrystals finite-size crack specimen finite element method cuboid
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Update on diagnosis and management of cuboid fractures 被引量:2
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作者 Antonios G Angoules Nikolaos A Angoules +1 位作者 Michalis Georgoudis Stylianos Kapetanakis 《World Journal of Orthopedics》 2019年第2期71-80,共10页
Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractur... Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractures should be detailed and the differential diagnosis, especially in the case of vague symptoms, should include the exclusion of all lateral foot pain causes. Conventional radiographs do not always reveal occult fractures, which can be under diagnosed especially in children. In this case, further investigation including magnetic resonance imaging or scintigraphy may be required. The treatment of these injuries depends on the particular fracture characteristics. Non-displaced isolated fractures of the cuboid bone can be effectively treated conservatively by immobilization and by avoiding weight bearing on the injured leg. In the case of shortening of the lateral column> 3 mm or articular displacement > 1 mm, surgical management of the fracture is mandatory in order to avoid negative biomechanical and functional consequences for the foot and adverse effects such as arthritis and stiffness as well as painful gait. In this review, an update on diagnosis and management of cuboid fractures is presented. 展开更多
关键词 cuboid FRACTURE DIAGNOSIS Treatment SURGERY
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Singularity-free expression of magnetic field of cuboid under undulating terrain 被引量:4
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作者 匡星涛 杨海 +1 位作者 朱晓颖 李伟 《Applied Geophysics》 SCIE CSCD 2016年第2期238-248,416,共12页
Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods ... Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. AT at all points in the source-flee space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain. 展开更多
关键词 Undulating terrain magnetic field of cuboid variable substitution analytical singularity
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长方体全张量磁梯度的两种正演公式对比 被引量:3
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作者 钟炀 管彦武 +1 位作者 石甲强 肖锋 《世界地质》 CAS 2019年第4期1073-1081,1090,共10页
全张量磁梯度测量是当前航空磁测的一个重要发展方向。正演是反演的基础,而长方体又是地下空间剖分的基本单元,故其正演公式具有重要的理论意义。笔者从前人给出的东南下坐标系和北东下坐标系的两种磁场三分量理论表达式出发,分别推导... 全张量磁梯度测量是当前航空磁测的一个重要发展方向。正演是反演的基础,而长方体又是地下空间剖分的基本单元,故其正演公式具有重要的理论意义。笔者从前人给出的东南下坐标系和北东下坐标系的两种磁场三分量理论表达式出发,分别推导了长方体全张量磁梯度的计算公式。理论模型的两种正演结果对比表明,两种公式的计算结果完全相同,但北东下坐标系更实用。该坐标系下的长方体全张量磁梯度理论表达式更加简洁,文中相同模型体的正演节省约10%的时间。 展开更多
关键词 全张量磁梯度 长方体 正演公式
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高温高湿环境下方块大体积海工混凝土抗裂性能研究 被引量:3
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作者 蒋震 向佳瑜 +3 位作者 冷政 黄辉 李曦 杨琼辉 《混凝土与水泥制品》 2017年第6期12-15,共4页
针对南海区域高温高湿环境,采用大粒径粗骨料、小坍落度的配合比设计方法,预埋冷却水管及创新施工养护方式,制备方块大体积海工混凝土。对其收缩性能、热学性能、水化产物、抗裂性能等方面进行分析,并结合工程应用,得出方块大体积海工... 针对南海区域高温高湿环境,采用大粒径粗骨料、小坍落度的配合比设计方法,预埋冷却水管及创新施工养护方式,制备方块大体积海工混凝土。对其收缩性能、热学性能、水化产物、抗裂性能等方面进行分析,并结合工程应用,得出方块大体积海工混凝土抗裂设计及施工的相关措施。研究表明,采用5~31.5mm(占比40%~50%)与31.5~63mm两种连续级配碎石拥有很好的紧密堆积效果,260h收缩率为4.03×10^(-4),低于5~31.5mm连续级配碎石的260h收缩率4.74×10^(-4);方块仿真模型和工程实体温度分析检测得出中心最高温度出现在浇筑后40h,接近70℃,中心温度和表层温度最大差值接近25℃;高温高湿环境下采用预埋冷却水管及养护剂+土工布+薄膜+土工布四层体系的养护方式对方块抗裂效果明显。 展开更多
关键词 高温高湿 方块 大体积 海工混凝土 收缩 抗裂
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An interactive approach for functional prototype recovery from a single RGBD image
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作者 Yuliang Rong Youyi Zheng +2 位作者 Tianjia Shao Yin Yang Kun Zhou 《Computational Visual Media》 2016年第1期87-96,共10页
Inferring the functionality of an object from a single RGBD image is difficult for two reasons:lack of semantic information about the object, and missing data due to occlusion. In this paper, we present an interactive... Inferring the functionality of an object from a single RGBD image is difficult for two reasons:lack of semantic information about the object, and missing data due to occlusion. In this paper, we present an interactive framework to recover a 3D functional prototype from a single RGBD image.Instead of precisely reconstructing the object geometry for the prototype, we mainly focus on recovering the object's functionality along with its geometry.Our system allows users to scribble on the image to create initial rough proxies for the parts. After user annotation of high-level relations between parts, our system automatically jointly optimizes detailed joint parameters(axis and position) and part geometry parameters(size, orientation, and position). Such prototype recovery enables a better understanding of the underlying image geometry and allows for further physically plausible manipulation. We demonstrate our framework on various indoor objects with simple or hybrid functions. 展开更多
关键词 FUNCTIONALITY cuboid PROXY PROTOTYPE part RELATIONS shape analysis
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均匀磁化长方体的磁张量无解析奇点正演方法 被引量:1
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作者 邰振华 柴琳 +1 位作者 黄德智 商宇航 《黑龙江科技大学学报》 2022年第3期286-292,共7页
长方体的磁张量正演公式存在解析奇点,降低了边界检测的实验效果、三维反演的收敛性。以均匀磁化长方体磁异常无解析奇点正演公式为基础,推导了直立长方体磁张量的无解析奇点正演公式,借助坐标变换方法,构建了倾斜长方体磁张量的无解析... 长方体的磁张量正演公式存在解析奇点,降低了边界检测的实验效果、三维反演的收敛性。以均匀磁化长方体磁异常无解析奇点正演公式为基础,推导了直立长方体磁张量的无解析奇点正演公式,借助坐标变换方法,构建了倾斜长方体磁张量的无解析奇点正演算法。实验表明,推导的长方体磁张量无解析奇点正演算法是正确的;地磁倾角与磁偏角能够影响磁张量的幅值与分布、磁异常向张量的转换精度,说明化磁极是磁张量高精度处理与解释的必要环节。 展开更多
关键词 长方体 磁张量 解析奇点 正演
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体内弹道射击角度的计算与分析 被引量:2
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作者 陈一清 龙飞 朱少建 《刑事技术》 2004年第3期7-9,共3页
目的 推断被枪击者在中弹瞬间所处的位置和姿势以及枪支击发时的位置。方法 采用立体几何作图法和三角函数计算法进行体内弹道射击角度计算。结果 可以准确计算枪弹弹道与人体解剖学三维断面———矢状面、冠状面、水平面产生的角度... 目的 推断被枪击者在中弹瞬间所处的位置和姿势以及枪支击发时的位置。方法 采用立体几何作图法和三角函数计算法进行体内弹道射击角度计算。结果 可以准确计算枪弹弹道与人体解剖学三维断面———矢状面、冠状面、水平面产生的角度。结论 可以确定被枪击者中弹瞬间的位置及体位或枪支击发时的位置 。 展开更多
关键词 弹道 射击角度 枪击案件 推测方法 案例应用
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Evaluation of rockburst proneness considering specimen shape by storable elastic strain energy 被引量:1
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作者 Song Luo Fengqiang Gong 《Deep Underground Science and Engineering》 2022年第2期116-130,共15页
To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of ... To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of both cylindrical and cuboid rock specimens under uniaxial compressive load was confirmed,and the energy storage coefficient was found to be unrelated to specimen shape.On the basis of LES law,two rockburst proneness indexes,namely the strain energy storage index(W_(et))and the potential energy of elastic strain(PES),were modified.Subsequently,the W_(et),PES,peak-strength strain energy storage index(W_(et))p,and peak-strength potential energy of elastic strain(PESp)were used to assess the rockburst proneness of the cylindrical and cuboid specimens.In addition,the fragment ejection course of specimens under test was recorded by a high-speed camera.Then,the rockburst proneness judgments obtained from the 4 indexes were compared with the qualitative data during rock destruction.The results show that,under similar stress conditions,specimen shape has an ignorable effect on the rockburst proneness as a whole.The judgment accuracy of the two modified indexes,especially that of the PESp,is favorably improved to evaluate the rockburst proneness of both cylindrical and cuboid specimens.However,misjudgment ofW_(et)^(p)and PESp may still occur in the assessment of rockburst proneness as these two indexes only consider the energy state before rock peak strength and the W_(et)^(p)is formulated in a ratio form. 展开更多
关键词 cuboid specimen elastic strain energy energy storage rockburst proneness shape effect uniaxial compression
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长方体上均匀分布的密度函数 被引量:2
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作者 陈光曙 《纯粹数学与应用数学》 CSCD 2009年第4期721-724,共4页
讨论了长方体上均匀分布密度函数问题,得到了长方体体积的估计量、估计量的点估计及估计量的密度函数.
关键词 估计量 均匀分布 密度函数 长方体
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足外侧区复合组织瓣移植的应用解剖 被引量:2
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作者 潘振宇 陈振光 +3 位作者 张发惠 谭金海 郑和平 谢昀 《武汉大学学报(医学版)》 CAS 2004年第5期562-564,共3页
目的 :为踝周部骨折、骨不连或合并软组织缺损的修复提供一种新术式。方法 :在 33侧乳胶灌注下肢标本上解剖并观测了足背外侧区血管的走行、分支、分布及吻合情况。结果 :足外侧区血管来自于跗外侧动脉、跟外侧动脉、外踝前动脉及腓动... 目的 :为踝周部骨折、骨不连或合并软组织缺损的修复提供一种新术式。方法 :在 33侧乳胶灌注下肢标本上解剖并观测了足背外侧区血管的走行、分支、分布及吻合情况。结果 :足外侧区血管来自于跗外侧动脉、跟外侧动脉、外踝前动脉及腓动脉穿支的降支 ,彼此相互吻合 ,并分支滋养趾短伸肌和皮肤 ,其中 ,跗外侧动脉是骰骨的主要血供来源。结论 :以上述 4条不同血管为蒂切取复合组织瓣 ,能一次性修复胫骨远端、踝部或距骨骨折、骨不连或合并软组织缺损。 展开更多
关键词 骰骨 趾短伸肌 足背 复合组织瓣
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Simplified Computation of Reflective Overpressure in Closed Cuboid Space Due to Internal Explosion 被引量:2
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作者 田力 李忠献 周清 《Transactions of Tianjin University》 EI CAS 2010年第6期395-404,共10页
A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all node... A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algori... 展开更多
关键词 closed cuboid space reference database reflective overpressure charge weight
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