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991.
司守奎 《高校应用数学学报(英文版)》1999,14(4)
In this paper,the boundary stabilization of the Timoshenko equation of a nonuniform beam,with clamped boundary condition at one end and with bending moment and shear force controls at the other end,is considered.It is proved that the system is exponentially stabilizable when the bending moment and shear force controls are simultaneously applied.The frequency domain method and the multiplier technique are used. 相似文献
992.
斜梁在热状态下非线性振动分岔 总被引:6,自引:1,他引:5
利用Galerkin原理及Melnikov函数法研究了斜梁在热状态下的非线性振动分岔,并讨论分析了温度、长高比、倾斜角对斜梁发生混沌运动区域的影响. 相似文献
993.
弹性支承圆弧梁内力分析 总被引:4,自引:2,他引:2
以现代桥梁及房屋结构为工程背景,提出弹性支承曲线梁计算模型,按结构力学方法推导出弹性支承圆弧梁的内力计算公式,分析讨论了竖向和抗扭弹性支承对内力的影响. 相似文献
994.
The photofragmentation of C_6 H_5I at 266 nm is investigated on the nuiversal crossed molecular beam machine, and the translational spectroseopy as well as the angular distribution of I atom is measured. The results reveal that under the laser intensity of 10~8 W/cm~2 the single-phuton dissociation competes with multi-photon processes. In singlephoton dissociation the anisotropy parameter β is 0.4 and the average translational energy is only 1.04 keal/mol, which indicates that this process is a slow predissociation. In two-photon phutofragmentation the average translational energy is 51.64 kcal/mol, which accounts for about 35% of the available energy. Another photofragmentation channel is even more faster, whose peak in time-of-flight spectra corresponds to four or five photon absorptions. The branching ratio of these three channels is determined to be about 3: 3: 4. 相似文献
995.
Keunjoo Kim Hong Seub Kim Hwack Joo Lee 《Journal of Solid State Electrochemistry》1999,3(7-8):417-423
The thermionic hole emissions from a p-type Si0.67Ge0.33 quantum well with a width of 7 nm and a point defect were investigated using deep level transient spectroscopy. An activation
energy of 0.22 eV from the quantum well is consistent with the heavy hole level from the bottom of the well. The defect-related
band with an energy of 0.30 eV originated from the space charge related to the point defect in the vicinity of the quantum
well heterostructure. The origin of the point-defect-related band was confirmed by photoluminescence and the deep level was
further clarified by using capacitance-voltage measurements and simulation by introducing a simple model of an interfacial
hole trap center. The deep hole trap center apparently disappeared by an annealing effect, indicating that point defects are
subject to thermal annealing. The microscopic measurement provides evidence on point defects in the quantum well structure
and the thermal annealing also enhances the thermionic hole emission from the quantum well structure.
Received: 22 August 1998 /Accepted: 15 February 1999 相似文献
996.
V. Bystritskii E. Garate J. Earthman A. Kharlov E. Lavernia X. Peng 《Theoretical and Applied Fracture Mechanics》1999,32(1):412
This paper presents experimental results on the application of Microsecond Plasma Opening Switch (MPOS) technology to Al alloy surface modification. The main objective of the experiments presented here was to study the change in the tensile and fatigue properties of the MPOS-treated Al2024, Al7075 alloy samples. The bending fatigue test was carried out both in air and in corrosive media. The measurements indicate significant improvement of fatigue properties for the treated 7075 alloy in corrosive media (1.5 times higher in fatigue limit). For the 2024 alloy the enhancement in fatigue lifetime for higher stresses was measured. Anodic polarization curve measurements were carried out at various values of fatigue cycles. 相似文献
997.
采用强流相对论电子束横向泵浦纯氩,获得了属于Ar的第三谱带范围内240nm中心谱区的光强随气压变化的关系.结果表明,压强为3×105Pa时是产生这一谱区的最佳气压,并证实了这一谱区是由带电的原子团簇产生的. 相似文献
998.
Summary The effects of electron beam irradiation on cork volatile compounds was studied at different doses (25, 100, 1000 kGy). Volatiles
were isolated from cork using the dynamic headspace-sampling technique, then identified by gas chromatography-mass spectrometry
(GC-MS). Similar gas chromatographic profiles were obtained for non-irradiated and irradiated corks. Quantitative differences
induced by the three doses were evaluated by calculating peak areas for each compound identified. The quantitative differences
between non-irradiated corks and those irradiated at 25 kGy were significant for only a few substances, whereas significant
quantitative differences were found in samples irradiated at 100 and 1000 kGy. For these doses, the content of volatile compounds
generally increased, especially that of aliphatic hydrocarbons and carbonyl compounds. The behaviour of radiolytic hydrocarbons
indicates that the mechanisms proposed for their formation in irradiated foods could take place even in cork. 相似文献
999.
Laser-radiation transfer in a Markov binary mixture is compared to transfer in an equivalent homogeneous medium. Within the
framework of a small-angle approximation a system of equations that describe the angular moments of the second order (angular
dispersion) for a laser beam and the equation for laser-beam intensity is obtained. The results of the calculations show a
significant effect of the stochastic nature of the medium on the intensity and the angular structure of the laser beam.
Deceased
Institute of Applied Optics, National Academy of Sciences of Belarus, 11, Belynitskii-Birulya St., Mogilev, 272793. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 36–42, January–February, 1999. 相似文献
1000.
This paper describes the application of multiple beam shearing interferometry to a position magnifying sensor. A multiple beam shearing interferometer (MBSI) with a shear plate wedged in the vertical direction produces sharp multiple beam fringes. When the lateral displacement of a point source (which gives rise to the input beam of the MBSI) or its image occurs in the horizontal direction, these fringes move vertically in a magnified manner. This characteristic was used in a position magnifying sensor to detect the displacement of a point image. The advantages of the sensor include a large displacement magnification (more than a hundred times) and a large working distance. 相似文献