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111.
转镜式高速相机扫描速度及其不均匀性测量 总被引:1,自引:0,他引:1
介绍了高速相机扫描速度不均匀性产生的原因、扫描速度测量的方法,简要地介绍了测量系统的工作原理,测时精度达到3ns,测速精度达到 3,最后给出了测量 GSJ型和SJZ-15型相机的结果。 相似文献
112.
Variation of the stress intensity factor along the front of a 3-D rectangular crack subjected to mixed-mode load 总被引:3,自引:0,他引:3
Summary The singular integral equation method is applied to the calculation of the stress intensity factor at the front of a rectangular
crack subjected to mixed-mode load. The stress field induced by a body force doublet is used as a fundamental solution. The
problem is formulated as a system of integral equations with r
−3-singularities. In solving the integral equations, unknown functions of body-force densities are approximated by the product
of polynomial and fundamental densities. The fundamental densities are chosen to express two-dimensional cracks in an infinite
body for the limiting cases of the aspect ratio of the rectangle. The present method yields rapidly converging numerical results
and satisfies boundary conditions all over the crack boundary. A smooth distribution of the stress intensity factor along
the crack front is presented for various crack shapes and different Poisson's ratio.
Received 5 March 2002; accepted for publication 2 July 2002 相似文献
113.
Ki Byung Sunwoo Seung Joon Park Seong Jae Lee Kyung Hyun Ahn Seung Jong Lee 《Rheologica Acta》2002,41(1-2):144-153
Three-dimensional numerical simulation of viscoelastic coextrusion process has been performed and numerical results were
compared with the experimental data of Karagiannis et al. (1990). By varying the magnitude of the second normal stress difference
and its ratio of Fluid I and Fluid II, we were able to control the interface profile and the degree of encapsulation along
the downstream direction. By increasing the parameter α (αFluid I=αFluid II) from 0.1 to 0.4 in the Giesekus model and increasing the α ratio (αFluid IαFluid II) between Fluid I and Fluid II from 2.0 to 4.0 in the permissible range of realistic polymeric systems, the interface profile
and the degree of encapsulation along the downstream direction were fitted with the experimental results. There was little
difference between the numerical results and the experimental data in the interface profile and the degree of encapsulation
along the downstream direction when the α ratio was set to 3.0 (0.3:0.1). Fluid I with larger magnitude of the second normal
stress difference protrudes into Fluid II with smaller magnitude of the second normal stress difference around the symmetric
plane, while Fluid II wraps around Fluid I near the side walls. As the ξ
1
ratio (ξ
1
,Fluid Iξ
1
,Fluid II) increases from 1.0 to 3.0 for the two-mode Phan-Thien and Tanner model, it was found that the curvature of the interface
profile increased, and the difference between the numerical results and the experimental data in the interface profile and
the degree of encapsulation along the downstream direction was almost negligible when the ξ
1
ratio was set to 3.0 (0.54:0.18). Although the parameters of viscoelastic models were fitted by using the shear viscosity
data only, quantitative agreements between the numerical results and the experimental coextrusion data were quite satisfactory.
Received: 24 April 2001 Accepted: 5 June 2001 相似文献
114.
被动桩问题是近年来岩土工程领域的一个研究热点,但是对于堆载下桩、土之间复杂的相互作用一直缺乏系统的三维分析。本文采用FLAC3D建立了有限差分模型,对单排桩三维工作性状进行分析,重点研究堆载条件、桩身刚度及土层分布对桩身位移和桩侧土压力的影响情况,并籍此对软土地基的桩、土共同作用机理加以阐述,得出一些有益结论。分析表明,软土地基中桩侧土压力的分布可简化为线性模式,本文对此进行了线性拟合。 相似文献
115.
Bruno Debus Dmitry Kirsanov Irina Yaroshenko Alla Sidorova Alena Piven Andrey Legin 《Analytica chimica acta》2015
In clinical analysis creatinine is a routine biomarker for the assessment of renal and muscular dysfunctions. Although several techniques have been proposed for a fast and accurate quantification of creatinine in human serum or urine, most of them require expensive or complex apparatus, advanced sample preparation or skilled operators. To circumvent these issues, we propose two home-made platforms based on a CD Spectroscope (CDS) and Computer Screen Photo-assisted Technique (CSPT) for the rapid assessment of creatinine level in human urine. Both systems display a linear range (r2 = 0.9967 and 0.9972, respectively) from 160 μmol L−1 to 1.6 mmol L−1 for standard creatinine solutions (n = 15) with respective detection limits of 89 μmol L−1 and 111 μmol L−1. Good repeatability was observed for intra-day (1.7–2.9%) and inter-day (3.6–6.5%) measurements evaluated on three consecutive days. The performance of CDS and CSPT was also validated in real human urine samples (n = 26) using capillary electrophoresis data as reference. Corresponding Partial Least-Squares (PLS) regression models provided for mean relative errors below 10% in creatinine quantification. 相似文献
116.
研发了一种多层复合微流控芯片,包含64细胞培养微孔阵列,该微阵列集成了细胞进样、水凝胶三维支架形成和持续灌流培养的过程.以MCF-7乳腺癌细胞为模型,连续培养中监测细胞存活率、细胞密度、增殖率和细胞内pH值,并同时进行冰冻切片后免疫组化染色.实验结果显示,乳腺癌细胞在水凝胶微球中增殖形成了类组织结构.E-cadherin及Vinculin在细胞内、细胞间隙均出现较强表达,提示水凝胶微球中细胞建立了细胞-细胞、细胞-间质连接.芯片上连续培养15天内细胞存活率保持在85%以上,细胞增殖率随时间延长而递减.细胞内pH值检测显示芯片3D培养细胞内部呈现明显的酸化,其程度随着细胞密度增大而增加.这种芯片肿瘤组织微阵列构建方法简单高效,有望发展成为肿瘤研究的有力工具. 相似文献
117.
采用简易、温和、实际耐用的水热方法制备了新型三维介孔立方体结构的钴酸锌纳米材料。每个钴酸锌立方体的边长大约在3-4μm之间,并由大量的纳米粒子和密集的孔隙所构成。通过氮吸附/脱附手段测试发现所制备的钴酸锌纳米材料具有较大的比表面积(41.4 m2?g~(-1))和介孔(6.32 nm)特性。使用钴酸锌纳米材料作为锂离子电池负极,金属锂作为正极组装锂电池并测试了材料的储锂性能。研究发现该电极材料在较高的电流密度下循环100周后,仍能呈现较高的可逆容量和超强的循环稳定性。这种优异的储锂性能主要归因于钴酸锌纳米材料的新型结构,这种介孔立方体结构能够加速锂离子的扩散,增加电极与电解液的接触面积并缓解锂离子嵌入/嵌出期间产生的体积膨胀。 相似文献
118.
119.
An experimental technique is presented for measuring the heat dissipation and localization during cyclic loading of materials.
The temperature field is measured by a number of thermistors and an infrared camera, which scans the specimen surface continuously.
The specimen is mounted inside an isothermal chamber. The measured whole-field temperature can be used for detection of damage
propagation and localization. The resolution of the technique under various boundary conditions is discussed using a onedimensional
model for the heat loss under steady-state conditions. Applications of the technique are demonstrated for specimens made of
fiber-reinforced ceramic and polymer matrix composites (PMCs). A methodology is proposed for measuring changes in damping
and stiffness properties of viscoelastic polymer matrix composites using the temperature rise of a cyclic loaded specimen.
It is demonstrated that for a ceramic matrix composite, where interfacial frictional sliding gives rise to heat dissipation,
the temperature resolution can be used for detection of stress-strain hysteresis with an accuracy better than that of the
stress-strain data. 相似文献
120.
面对需要实时计算的相机位姿估计问题,针对经典的广泛应用的正交迭代算法,提出了一种加速正交迭代算法。其关键思想是将每一次迭代过程规整化,从而提炼出每一次迭代的重复计算,若将此重复计算在迭代开始前提前计算,则可以大幅度的减少迭代过程中的计算量,使得每一次迭代的计算复杂度从O(n)降低为O(1)。因此,可以在更短的时间内迭代更多的次数,从而获得更高的精度。进行了对比实验,结果显示本加速算法计算精度更高,速度更快。并通过实验提出了选择稳健n点透视(RPn P)计算初值,再使用加速正交迭代算法进行迭代运算的方法,在控制点不多的情况下,是一种精度接近最大似然估计,计算速度最快的算法。 相似文献