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121.
A residual method of finite differencing the governing differential equation for the elliptic transport problem is presented. The new finite differencing technique is applied to (1) the one-dimensional transport problem and (2) the cavity flow problem for numerical illustrations. The results indicate the validity of the residual method of finite differencing. The usual method of term-by-term finite differencing, and considerations such as central differencing, hybrid differencing and upwind differencing are not needed in the present residual method. 相似文献
122.
Summary It was possible to obtain film exposures of the WAXS-diagram (2 50°) of a PE-fraction
in the temperature range from 10 K to 300 K by using a special low temperature Guinier-chamber. The crystallographica-,b-andc-axis has been calculated from the positions of all reflexions. The different behaviour of their expansion coefficients can be explained by activation of rotational- and torsional-vibrations. If we take the number of net planes as constant and consider a temperature-independent part resulting from paracrystalline disorder (built up during crystallization), we can describe the linear increasing of the integral widths of the reflexions with decreasing temperature (10 ... 100%) with building up of inherent stresses inside the crystals.
Zusammenfassung Eine spezielle Tieftemperatur-Guinier-Kammer ermöglichte es, Filmaufnahmen der Röntgenweitwinkelstreukurve (2 50°) einer hochkristallinen Polyäthylen-Fraktion im Bereich von ca. 10 K bis 300 K zu erhalten. Das unterschiedliche Temperaturverhalten der Ausdehnungskoeffizienten der kristallographischena-,b- undc-Achse, berechnet aus der Lage aller auswertbaren Reflexe, kann durch Anregung von Torsions- und Rotationsschwingungen erklärt werden. Unter der Annahme konstanter Kristallitgrößen sowie eines temperaturunabhängigen parakristallinen Gitterstörungsanteils (hervorgerufen durch Defekteinbau bei der Kristallisation), kann die starke Zunahme der integralen Breiten der Reflexe (bis ca. 100%) zu tiefen Temperaturen auf Eigenspannungen in den Kristalliten zurückgeführt werden.相似文献
123.
K.F. Song S. Kassi V.I. Perevalov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(3):332-31
In a previous contribution [Kassi S, Song KF, Campargue A. High sensitivity CW-cavity ring down spectroscopy of 12CO2 near 1.35 μm (I): line positions. JQSRT 110 (2009) 1801-1814], the line positions analysis of the high sensitivity absorption spectrum of carbon dioxide has been reported in the 7123-7793 cm−1 region. In this second contribution, the spectral region investigated by CW-cavity ring down spectroscopy has been extended up to 7917 cm−1. It added about 400 lines to our previous list of about 2500 transitions. These additional lines include transitions belonging to six newly observed 12C16O2 bands for which we provide the spectroscopic parameters. Over the whole 7123-7917 cm−1 region, the accurate intensities of about 2900 lines belonging to four isotopologues (12C16O2, 13C16O2, 16O12C18O and 16O12C17O) were retrieved with an average accuracy of 3%. Intensity values range between 1.2×10−29 and 4.1×10−25 cm/mol. Compared to the present version of the carbon dioxide spectroscopic databank recently adopted for the HITRAN database, important deviations were evidenced for some weak bands of the main isotopologue. The CW-CRDS intensity data relative to a total of 46 12C16O2 bands together with selected intensity information available in the literature for nine bands have been fitted simultaneously using the effective operators approach. The ΔP=11 set of the 12C16O2 effective dipole moment parameters has been refined leading to a much better agreement with the measured intensity values. In addition, the ΔP=10 effective dipole moment parameters of the 16O12C18O minor isotopologue were determined for the first time. The obtained results will help to improve the carbon dioxide spectroscopic databank (CDSD). 相似文献
124.
Agnès Perrin Samir Kassi 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2246-2255
The high-resolution absorption spectrum of the 4ν1+ν3 band of the 14N16O2 molecule was recorded by CW-Cavity Ring Down Spectroscopy between 6575 and 6700 cm−1. The assignments involve energy levels of the (4,0,1) vibrational state with rotational quantum numbers up to Ka=8 and N=48. A large majority of the spin-rotation energy levels were reproduced within their experimental uncertainty using a theoretical model which takes explicitly into account the Coriolis interactions between the spin-rotational levels of the (4,0,1) vibrational state and those of the (4,2,0) and of (0,9,0) dark states, the anharmonic interactions between the (4,2,0) and (0,9,0) states together with the electron spin-rotation resonances within the (4,0,1), (4,2,0) and (0,9,0) states. Precise vibrational energies, rotational, spin-rotational, and coupling constants were determined for the {(4,2,0), (0,9,0), (4,0,1)} triad of interacting states. Using these parameters and the value of the transition dipole-moment operator determined from a fit of a selection of experimental line intensities, the synthetic spectrum of the 4ν1+ν3 band was generated and is provided as Supplementary Material. 相似文献
125.
Hongxin Shi Xiudong Sun Suhua Luo Yongyuan Jiang Qingxin Meng 《Optics & Laser Technology》2010,42(7):1118-1121
A series of Hf:Fe:LiNbO3 crystals were grown by the Czochralski technique with various doping concentrations of HfO2. Their defect structures were analyzed by the UV-visible absorption spectra and infrared absorption spectra. The optical damage resistance of Hf:Fe:LiNbO3 crystals was measured by the photo-induced birefringence change and the transmitted light spot distortion method. The results show that the optical damage resistance ability of Hf:Fe:LiNbO3 crystals enhances remarkably with the HfO2 concentration increasing when the HfO2 concentration is lower than its threshold concentration (4 mol%). However, when the HfO2 concentration exceeds its threshold concentration, the optical damage resistance ability of the crystals returns to decrease. This unusual behavior is explained by using the photovoltaic field produced in the crystals. 相似文献
126.
We propose the optical generation of W states for three atomic and four atomic qubits, with each qubit trapped in a separate cavity and coupled to the cavity laser. A single-photon source and two classical fields are employed in the present scheme. By encoding the quantum information of each qubit on the degenerate ground states of the atom, we obtain the atomic entanglement that is relatively stable against spontaneous emission. It is demonstrated that the three- and four-atomic W states can be produced deterministically via a proper manipulation of the atom-cavity interaction sequence and time. Generalization of the present scheme to prepare multi-atomic W states is also discussed. 相似文献
127.
Laser conditioning of high-reflective and anti-reflective coatings in vacuum environments 总被引:1,自引:0,他引:1
Laser conditioning effects of the dielectric mirror coatings in vacuum environments were investigated. The laser-induced damage thresholds (LIDT) in vacuum environments before and after laser conditioning were compared. It is found that laser conditioning in vacuum environments decrease the LIDT of the component. Laser conditioning effects in vacuum and atmosphere environments were also compared and investigated. The negative effects of laser conditioning in vacuum environments were discussed and analyzed with defect statistical model, energy dispersive X-ray analysis and absorption measurements. 相似文献
128.
In this study, a generalized and easy to use method based on Hill's equation and chain matrix concept is used to analyze the electromagnetic wave propagation in stratified dielectric and inhomogeneous media with arbitrary profiles.Numerical simulations are performed to compute the reflection and transmission of several Electromagnetic Bandgap (EBG) structures for various permittivity profiles and given polarization as well as incidence angles of driving fields.Multilayer structures are analyzed and optimized to enhance their selectivity performances. Obtained results agree excellently well with other published data. 相似文献
129.
Fenglei Gao 《Applied Surface Science》2010,256(11):3357-9406
Chemical vapor deposition (CVD) growth of horizontally aligned single-walled carbon nanotubes (SWNTs) was studied using two representative carbon source sources: ethanol and methane. The resulting SWNTs were compared for similar reaction conditions which were based on the formation of Ni metal nanoparticles selective electrochemical deposition (SED) on the defect sites of SWNTs. The products were analyzed by Raman spectroscopy and SEM. The results demonstrate that methane was much better carbon source for growing high quality horizontal alignment of SWNTs than ethanol due to the etching effects of OH radicals on the SWNTs. 相似文献
130.
贴片电阻表面缺陷自动识别方法 总被引:1,自引:0,他引:1
贴片电阻生产过程中的缺陷主要依靠人工在显微镜下检测,速度慢、长期成本高、误检率高.针对贴片电阻单元具有排列整齐、结构简单、图像灰度级少的特点,在贴片电阻图像二值化、边缘提取、直线检测基础上,以相邻电阻单元的相关系数作为电阻缺陷判别依据,提出基于子图投影匹配的快速缺陷检测方法.采用主分量分析法压缩图像数据量,提取缺陷特征,以基于支持向量机对贴片电阻缺陷进行分类并建立实验系统.缺陷检测及识别实验表明,缺陷检测正确率为92.5oo,算法的快速性和识别准确度满足系统快速高精的要求. 相似文献