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61.
The temperature and angular dependences of the EPR spectra of Mg[H2O]6SiF6:Mn2+ crystal were investigated in order to clarify the successive phase transitions and existence of the incommensurate phase. Five successive phase transitions were found to occur, and phase II was found to be incommensurately modulated. The modulated structure is caused mainly by the vibrational displacement of the Mg[H2O]2+ 6 ion along the c-axis. The soliton density of this phase is almost independent of temperature and remains equal to unity. 相似文献
62.
We address risk minimizing option pricing in a regime switching market where the floating interest rate depends on a finite state Markov process. The growth rate and the volatility of the stock also depend on the Markov process. Using the minimal martingale measure, we show that the locally risk minimizing prices for certain exotic options satisfy a system of Black-Scholes partial differential equations with appropriate boundary conditions. We find the corresponding hedging strategies and the residual risk. We develop suitable numerical methods to compute option prices. 相似文献
63.
对单模激光增益模型的光强方程加入调频信号,用线性化近似方法计算了以δ函数形式关联的两白噪声驱动下光强的输出功率谱及信噪比. 结果表明,信噪比随抽运噪声和量子噪声强度的变化可出现典型随机共振,受调制信号振幅的影响,信噪比随载波信号频率和调制信号频率的变化出现抑制、单调上升、共振、抑制和共振等几种情况.
关键词:
抽运噪声
单模激光
随机共振
调频信号 相似文献
64.
推导出用于测量半导体载流子输运特性(载流子寿命、载流子扩散系数和前表面复合速度)的调制自由载流子吸收(modulated free carrier absorption, MFCA)检测技术的三维理论模型,给出了调制自由载流子吸收检测信号与调制频率和抽运-探测光相对距离的关系.定性分析了在不同调制频率时各个载流子输运参数对径向位置扫描曲线(信号与两束光相对距离的关系)的影响,结果表明调制自由载流子吸收检测信号对各个参数的灵敏度随抽运-探测光相对距离的增加而增加.仿真和实验结果表明,通过拟合不同调制频率时调
关键词:
调制自由载流子吸收
载流子输运特性
径向位置扫描 相似文献
65.
This paper reports on the numerical investigations of Taylor-Couette flow of radius ratio η = 0.25–0.6 performed at low Reynolds numbers Re = 100–200. The inner cylinder and the bottom end-wall rotate, while the outer cylinder and the top end-wall are held fixed. A fully 3D DNS code based on the spectral Chebyshev – Fourier approximation is used. This study is complementary to those of Mullin and Blohm (Phys. of Fluids 2001, vol 13, 136–140) and Lopez et al. (J. Fluid Mech. 2004, vol 501, 327–354) where investigations have been performed for radius ratio 0.5. The 1-cell and 3-cell structures found by these authors are shown to exist for a wide range of radius ratios, and the transition processes between them are qualitatively similar. These structures show hysteresis, disappearing at saddle-node bifurcations which connect at a cusp point in the (Re, Γ) plane. This cusp exists for the entire range of 0.1 < η < 0.75, and it traces out a parabolic curve in the (Re, Γ) plane, reaching a minimum Re at η = 0.375. The detailed 3D DNS computations provide a lot of new information about such phenomena as the modulated rotating wave, the period doubling cascade and homoclinic collision. The results show that the period doubling bifurcation is important in the flow when the radius ratio is close to η = 0.375. 相似文献
66.
通道调制型偏振成像技术是一种体积紧凑、空间分辨率高且能够实时获取全偏振信息的新型偏振成像探测技术. 但该技术目前只能实现准单色光的全偏振探测, 严重制约了其实用化. 本文首先对宽带光通道调制型偏振成像出现混叠现象的原因进行了分析, 得出载波频率是限制波段宽度的主要因素. 据此在空间频谱域上分析并推导了通道调制型偏振成像系统的光谱宽度限制判据公式, 同时通过模型仿真得到了系统的极限有效光谱范围, 与理论推导公式结果进行了对比分析, 验证了判据的准确性. 基于该判据可预测给定通道调制型偏振成像系统的有效工作波段, 同时还可为扩展系统波段宽度提供理论支撑. 相似文献
67.
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69.
The quasi-isothermal curing of a diepoxide resin with a triamine of polyoxypropylene was studied by alternating differential scanning calorimetry (ADSC), which is a temperature modulated DSC technique. The complex heat capacity measurements allows to analyse the vitrification process at curing temperatures (Tc) below the maximum glass transition of the fully cured epoxy (Tg∞=85.8°C). Initially, the modulus of the complex heat capacity, |C*p|, increases until a maximum (conversion between 0.42 and 0.56) and then decreases. This step is followed by an abrupt decay of |C*p|, due to the vitrification of the system, which allows the determination of the vitrification time. This value agrees well with that determined by the partial curing method. The phase angle and out-of-phase heat capacity show an asymmetric wide peak during the vitrification process. The change in |C*p| at vitrification decreases with the increase of Tc becoming zero at temperature Tg∞. This epoxy-triamine system shows a delay of the vitrification process respect to other model epoxy systems probably due to the presence of polyoxypropylene chains in the network.
The decay of |C*p| during vitrification may be normalised between unity and zero by defining a mobility factor. This mobility factor has been used to simulate the reaction rate during the stage where the reaction is controlled by diffusion. The observed reaction rate is simulated by the product of the kinetic reaction rate, determined by the autocatalytic model, and the mobility factor. 相似文献
70.
The steady state of temperature modulated power compensation DSC has been theoretically investigated for measurements of complex
heat capacity, taking accounts of heat capacities of heat paths, heat loss to the environment, and mutual heat exchange between
the sample and the reference material. Thermal contact between the sample cell and the cell holder is also taken into accounts.
Rigorous and general solutions are obtained. From these solutions application of the technique to heat capacity measurements
is discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献