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951.
952.
We present the next‐to‐next‐to‐leading order post‐Newtonian (PN) spin(1)‐spin(2) Hamiltonian for two self‐gravitating spinning compact objects. If both objects are rapidly rotating, then the corresponding interaction is comparable in strength to a 4PN effect. The Hamiltonian is checked via the global Poincaré algebra with the center‐of‐mass vector uniquely determined by an ansatz. 相似文献
953.
Timo Nousiainen Olga Muñoz Päivi Mauno 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(3):420-433
Light scattering by large mineral-dust particles with small-scale surface roughness is investigated by comparing model simulations with laboratory-measured scattering matrices of two distinct dust samples collected from the Sahara desert. The samples have been chosen on the basis of their large effective radii, and the simulations are based on their measured size distributions. Size parameters larger than about 30 are modeled using a modified ray-optics model RODS (Ray optics with diffuse and specular interactions), while smaller particles are simulated with a T-matrix model. RODS allows us to mimic the surface roughness of large dust particles by covering the particle surface by a thin layer of external scatterers with specific single-scattering properties. The Gaussian-random-sphere geometry is used for the shapes of large dust particles. Small particles are modeled as an axial-ratio distribution of spheroids with smooth surfaces. One of the samples consists wholly of large particles and its scattering matrix can be reproduced very well by the RODS model, except for the phase function. The incorporation of wavelength-scale roughness is, however, necessary for good fits. The other sample, consisting of both small and large particles, proves more challenging to match with simulations. The analysis indicates, however, that the difficulties arise at least partially from the small-particle contribution, while RODS results are consistent with the measurements. Further, the results imply that the agreement with measurements would improve if roughness could also be accounted for in the small-particle simulations. Overall, the RODS method seems promising for modeling the optical properties of mineral-dust particles much larger than the wavelength. 相似文献
954.
The nonlinear response of the experimental system and the saturation of fringe patterns can induce the fluctuating phase error in the projection grating phase-shifting profilometry. Two major factors of the fluctuating phase error are discussed by simulation. The fluctuating phase error caused by the nonlinear response of the system is four times the frequency of the fringe pattern when the conventional four-frame phase extracting algorithm is used. However, such error can be decreased by five-frame algorithm. On the other hand, the fluctuating phase error caused by the fringe saturation is five times the frequency of the fringe pattern by using conventional five-frame phase extracting algorithm. A novel phase recovering algorithm is used to decrease the phase error caused by the saturation. Furthermore, the applicability range of the proposed phase recovering algorithm is analyzed by simulation and experiments with different saturation degree of the fringe pattern and nonlinearity of the measurement system. 相似文献
955.
956.
Based on the theory of Klein-Gordon scalar field particles,the Hawking radiation of a higher-dimensional Kerr-anti-de Sitter black hole with one rotational parameter is investigated using the beyond semi-classical approximation method.The corrections of quantum tunnelling probability,Hawking temperature and Bekenstein-Hawking entropy are also included. 相似文献
957.
针对基于DSP的高功率TEA CO2激光器控制系统直接利用DSP F2812内置A/D转换器(ADC)进行模拟量采样时存在转换误差较大,且模拟量易受电磁干扰等问题,从硬件和软件两个角度提出了校正DSP2812内置ADC的方法。硬件上采用硬件模拟滤波和隔离等手段对输入的模拟量进行处理;软件校正则通过将两路给定的参考电压值送入DSPF2812内置A/D转换器的两个转换通道,计算出ADC的偏置误差和增益误差,以此误差对其它通道A/D转换器进行校正。最后,实验分析了参考电压和A/D采样时钟频率对A/D转换精度的影响。结果表明,提出的方法能有效地提高A/D转换器的精度,A/D转换误差达到±3 LSB,特别是在对腔压值精度要求很高的0~12 000 Pa区段,A/D转换精度达±1 LSB,可以保证TEA CO2激光器的可靠运行。 相似文献
958.
Inma Peral Jonathan McKinlay Michael Knapp Salvador Ferrer 《Journal of synchrotron radiation》2011,18(6):842-850
A concept is given for describing multicrystal analyser detectors (MADs), as they are in use for synchrotron powder diffraction, on the basis of the Rowland circle construction. The Rowland circle is typically used to describe focusing geometries and can be adapted for the case of MADs working at a single energy as well as in a limited energy range. With this construction it is also possible to quantify and optimize the walk of the beam along non‐central crystals which is inevitable in certain detector designs. The results of this geometrical inspection are correlated with a real detector design that is implemented at the ALBA synchrotron facility in Spain. An error budget is given to estimate the influence and amount of tolerance of the manufacturing process. 相似文献
959.
本文研究了生物组织的改进的δ-P1近似漫反射光学模型,推导了含有等效光源一阶矩的双点源近似空间分辨漫反射解Rδ-P1(ρ).研究表明,考虑等效光源一阶矩的光学模型,较好地描述了具有强的前向散射特性和较大吸收系数的生物组织散射特性;与漫射近似下的漫反射率RSDA(ρ)相比,新的光学模型能较好地描述光源附近的漫辐射强度分布,并且由于解析表达式中含有散射相函数的二阶参量γ,这对
关键词:
组织光学
1近似')" href="#">δ-P1近似
等效光源
微区漫反射 相似文献
960.