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光笔式单目视觉测量系统的关键技术 总被引:4,自引:0,他引:4
为了对机械加工部件进行高精度、大尺寸、三维立体空间的现场实时测量,建立了光笔式单目视觉测量系统。对该系统中的新型光笔工艺、算法转换模型、摄像机焦距的优化、光笔笔尖位置的标定进行了研究。首先提出了一种利用光刻工艺设计制作的新型光笔,其次,基于近景摄影测量学中的单像空间后方交会原理,建立了一种新的光笔坐标系与摄像机坐标系之间的转换模型,通过最小二乘平差法循环迭代求解最优的单像空间外方位元素,从而确定了转换模型基本参数。最后,分析了摄像机焦距对光笔式单目视觉测量系统结果的影响,并提出了一种确定相对准确焦距和光笔测头在光笔坐标系下的位置的方法。实验结果表明:摄像机坐标系下x轴、y轴、z轴方向的稳定性误差分别为0.042、0.048、0.066 mm;测量最大误差为0.173 mm,较大程度上满足了光笔式单目测量系统稳定性强和精度高的要求。 相似文献
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V. Ya. Artyukhov T. N. Kopylova L. G. Samsonova N. I. Selivanov V. G. Plotnikov V. A. Sazhnikov A. A. Khlebunov G. V. Mayer M. V. Alfimov 《Russian Physics Journal》2008,51(10):1097-1111
A detailed account of quantum chemical procedures for estimating the rate constants of the photophysical processes at work
in polyatomic organic molecules is given. The results obtained from combined experimental and theoretical research into the
spectral-luminescent properties of acridine, 9-aminoacridine, 2,7-dimethyl-9-diphenylaminoacridine, and of their protonated
forms are reported. The electronic absorption and fluorescence spectra of acridine have been investigated at room temperature
in ethanol solution of varying pH and in other solvents of different chemical nature and polarity. The energy of excited states,
the rate constants of the deactivation of the excited states, and the dipole moments obtained by quantum chemical methods
for the examined compounds are presented. The findings of the investigations are discussed.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 93–107, October, 2008. 相似文献
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In the present work, electronic structure, chemical bonding and thermal stability of Li-N-H system for hydrogen storage were calculated by a first principle approach. On the basis of the thermal analysis of this system, pressure-composition-temperature (PCT) isotherm measurements of hydrogen desorption were performed and analyzed. The theoretical and experimental enthalpies of this system were calculated as −75.67 and −69.17 kJ/mol of H2, which agree well with other corresponding findings of −73.6 and 66.1 kJ/mol of H2, respectively. The theoretical and experimental values of desorption enthalpies in this study are reasonably agreeable with each other. 相似文献
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《Magnetic resonance imaging》1998,16(7):773-785
Diffusion tensor imaging (DTI) is a modality known to be highly sensitive to the detrimental effects of experimental noise. Here, using Monte Carlo simulations, we compare and contrast how noise complicates the measurement of diffusion anisotropy in diffusion tensor and conventional diffusion-weighted imaging (DWI). As the signal-to-noise ratio (SNR) decreases below a value of approximately 20, the eigenvalues (λi) of the diffusion tensor D are found to diverge rapidly from their true values, with the result that the measured anisotropy can be significantly in error and isotropic structures falsely assigned a high level of anisotropy. The effect of noise on the rotationally variant indices, calculated from a conventional diffusion-weighted imaging experiment, is found to be much less insidious, because the apparent diffusion coefficients (ADCs) diverge only slowly as the signal-to-noise decreases. Thus, although rotationally variant indices almost always underestimate the true diffusion anisotropy, they show only a small susceptibility to experimental noise and hence, are preferred to their rotationally invariant counterparts when the signal-to-noise ratio is small. 相似文献
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A theoretical and experimental study on all-normal-dispersion Yb-doped mode-locked fiber lasers 下载免费PDF全文
We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schrdinger (CNLS) equation, a model simulating the mode-locked process of an allnormal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller (PC) along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9mW at repetition rate 36MHz are obtained. 相似文献
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The mid-IR and Raman spectra of 8-hydroxy-2-quinolinecarboxylic acid (8HQC) were recorded. These spectra were interpreted with the help of B3LYP/6–311 ++G(d,p) calculations and potential energy distribution (PED) analysis. As a result of the calculations, seven tautomers were determined among many stable conformations. The experimental spectra were concordant with the theoretical data of one tautomer. In the functional group region overtone and combination bands were detected and assigned. In addition, because of several peaks in the IR spectrum, it was proposed that the 8HQC exhibits dimerization in condensed phase. Possible dimeric forms of 8HQC were evaluated at the same level of theory, and it has been seen that the calculation results confirm the above proposal. 1H and 13C NMR chemical shifts of 8HQC have been calculated, and compared with the experimental data. The frontier molecular orbital properties and the atomic charges were also theoretically obtained and presented. 相似文献
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The aim of this paper is to discuss the possible appearance of non-perfect grain boundary dislocations in grain boundaries in a variety of materials. To begin with, we survey some of the different theoretical treatments which enable grain boundary dislocations and grain boundary structures to be described. The emphasis is put on more recent ideas, and on illustrating the power of group theory in identifying non-perfect grain boundary dislocations. A derivation of the geometric characteristics of interfacial dislocations is carried out in a simple and tutorial way, in a number of representative examples. It is shown that grain boundary dislocations may be divided into three classes: (1) perfect grain boundary dislocations, (2) imperfect grain boundary dislocations, and (3) partial grain boundary dislocations. Experimental transmission electron microscope evidence is then presented for boundaries in the diamond cubic structure, and it is shown that imperfect and partial grain boundary dislocations play an important role in this system. Finally, a comparison of some grain boundary dislocation types in different materials is given. 相似文献
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We present a robust analysis of the spectral fluctuations exhibited by the light meson spectrum. This analysis provides information about the degree of chaos in light mesons and may be useful to get some insight on the underlying interactions. Our analysis unveils that the statistical properties of the light meson spectrum are close, but not exactly equal, to those of chaotic systems. In addition, we have analyzed several theoretical spectra including the latest lattice QCD calculation. With a single exception, their statistical properties are close to those of a generic integrable system, and thus incompatible with the experimental spectrum. 相似文献
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系统参数标定是结构光三维测量系统的关键问题之一,标定板特征圆圆心检测精度与投影仪、相机镜头gamma效应引起的相位误差是系统参数标定的主要误差来源。采用Sobel算子粗定位标定板特征圆的边缘点,以正交傅里叶-马林矩(OFMM)算子对边缘点进行亚像素定位,用椭圆拟合法确定特征圆圆心的方法提高标定板特征圆检测精度。同时,推导结构光三维测量系统gamma非线性数学模型,将计算得到的系统gamma值的倒数作为投影正弦光栅的指数以降低gamma效应引起的相位误差。实验结果证明了该方法的准确性,与不采用亚像素边缘检测与gamma校正相比,X、Y方向的标定精度分别提高约3.5倍与5倍。 相似文献
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M. Agostinha R. Matos Margarida S. Miranda Natália A. B. Pinto Victor M. F. Morais N. Dhananjaya Joel F. Liebman 《Molecular physics》2013,111(14):1885-1894
The standard (p°?=?0.1?MPa) molar enthalpy of formation for solid and gaseous diphenic anhydride (2,2′-biphenyldicarboxylic anhydride, dibenz[c,e]oxepin-5,7-dione) was derived from the standard molar enthalpy of combustion, in oxygen, at T?=?298.15?K, measured by static bomb combustion calorimetry, and the standard molar enthalpy of sublimation, at T?=?298.15?K, measured by Calvet microcalorimetry: ?(258.4?±?4.9) kJ?mol?1. In addition, ab initio and density functional theory calculations have been performed at a variety of levels. The degree of aromaticity of diphenic anhydride is discussed in the context of other oxygen-containing (ring and keto) heterocycles and related carbocycles: this species is surprisingly destabilized. 相似文献
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An account of the magnetoacoustic effect in aluminum alloys having additions of iron, copper magnesium, zinc, and silicon is given. The problem of the torsional oscillations of a metallic, electrically-conducting isotropic specimen in a magnetic field is considered, and experimental data are given. 相似文献
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对四方4/mmm、六角6/mmm和三角3m等晶体栅条反射系数进行了详细理论分析,给出具体的数学表达式,不同于已有的立方m3m栅条反射系数理论计算公式。根据理论分析结果给出112°旋转X切Y传LiTaO3基片上的铝短路反射栅和沟槽的反射系数。用实验方法研究了112°LiTaO3基片上的沟槽填铝短路反射的反射特性,得到了内反射为零的条件。证明了在112°LiTaO3基片上可用沟槽填铝单指结构实现无内反射的结论。将上述结果应用于单指无内反射滤波器的研制,得到了中心频率255 MHz、带宽约10 MHz、带内畸变小于0.4 dB的带通滤波器。 相似文献
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J. López-Solano P. Rodríguez-Hernández A. Muñoz D. Santamaría-Pérez F. J. Manjón S. Ray 《高压研究》2013,33(1):58-63
HgWO4 at ambient pressure is characterized using a combination of ab initio calculations, X-ray diffraction and Raman scattering measurements. The effect of low pressure and temperature on the structural stability is analysed. Extending our ab initio study to the range of higher pressures, a sequence of stable phases up to 30 GPa is proposed. 相似文献
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BAGLAYAN zge KESAN Gürkan PARLAK Cemal ALVER zgür SENYEL Mustafa 《中国科学:物理学 力学 天文学(英文版)》2014,57(9):1654-1661
FT-IR and Raman spectra of 1-cyclopentylpiperazine(1cppp)have been experimentally examined in the region of 4000–200cm-1.The optimized geometric parameters,conformational equilibria,normal mode frequencies and corresponding vibrational assignments of 1cppp(C9H18N2)are theoretically examined by means of B3LYP hybrid density functional theory(DFT)method together with 6-31++G(d,p)basis set.On the basis of potential energy distribution(PED)reliable vibrational assignments have been made and the thermodynamics functions,highest occupied and lowest unoccupied molecular orbitals(HOMO and LUMO)of 1cppp have been predicted.Calculations are employed for four different conformations in C1 and Cs point groups of 1cppp in gas phase.Comparison between the experimental and theoretical results indicates that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and the structural parameters,vibrational frequencies and assignments.Furthermore,C1(equatorial-axial)point group has been found as the most stable conformer of 1cppp. 相似文献