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611.
Feimin Huang Jie Kuang Dehua Wang Wei Xiang 《Journal of Differential Equations》2019,266(7):4337-4376
In this paper, we study the stability of supersonic contact discontinuity for the two-dimensional steady compressible Euler flows in a finitely long nozzle of varying cross-sections. We formulate the problem as an initial–boundary value problem with the contact discontinuity as a free boundary. To deal with the free boundary value problem, we employ the Lagrangian transformation to straighten the contact discontinuity and then the free boundary value problem becomes a fixed boundary value problem. We develop an iteration scheme and establish some novel estimates of solutions for the first order of hyperbolic equations on a cornered domain. Finally, by using the inverse Lagrangian transformation and under the assumption that the incoming flows and the nozzle walls are smooth perturbations of the background state, we prove that the original free boundary problem admits a unique weak solution which is a small perturbation of the background state and the solution consists of two smooth supersonic flows separated by a smooth contact discontinuity. 相似文献
612.
613.
顺序注射化学发光法测定药物中的抗坏血酸 总被引:1,自引:0,他引:1
基于在酸性介质中KMnO4氧化抗坏血酸产生化学发光反应,HCHO的存在能使发光强度增强的原理,建立了顺序注射技术与化学发光分析联用测定痕量抗坏血酸的新方法。对进样顺序、体积、流速和浓度各因素进行了优化,在150μL进样体积下,方法的线性范围为1.0×10-9~2.0×10-6mol/L,检出限(3σ)为5.0×10-10mol/L,方法的相对标准偏差为1.3%(1.0×10-7mol/L,n=11)。采样频率为80样/h。应用该法测定维生素C针剂和片剂中的抗坏血酸,结果与标准方法一致。 相似文献
614.
615.
The results of a comparative study (theoretical and experimental) of two original approaches for spectral control of two-wavelength pulsed Ti:sapphire (Ti:S) lasers and the most popular conventional methods are presented. Single line operation as a particular case is considered. We compare our own methods: (i) combined dual pulse pumping–passive self-injection locking (DPP–PSIL) and (ii) coupled cavity dye laser injection locking (CCLIL) with the conventional methods: (i) intracavity selection (IS), (ii) PSIL and (iii) traditional injection locking using an external dye laser. The most important criteria—laser efficiency, emission line width, tuning range, spectral purity and buildup time are compared under optimized conditions. The comparison is made using the same pump source with constant output energy in each case. The results serve as a basis for choosing correctly the most suitable spectral control technique for a particular Ti:S laser application. It is shown that the DPP–PSIL method guarantees a remarkable improvement of the Ti:S laser performance (nearly doubling the laser efficiency with the same line width and comparable laser tuning range as IS, combined with a protection of the selectors). The CCLIL approach assures a maximum laser efficiency in narrow line emission in addition to a minimal and reproducible buildup time. The IS method provides a maximal tuning range. 相似文献
616.
617.
注入锁定TEA CO2激光器激光脉冲特性分析 总被引:1,自引:0,他引:1
本文在一般的TEACO2激光器的动力学方程的基础上,给出注入锁定情况下TEACO2激光器的动力学方程组,并进行数值计算,结果表明,TEACO2激光器注入锁定激光脉冲宽度比自由运转时的变宽了,脉冲峰值功率降低,而且激光脉冲产生的时间提前,这与实验规律相吻合。 相似文献
618.
An analytical method has been proposed to optimise the small-signaloptical gain of CO2-N2 gasdynamic lasers (gdl) employing two-dimensional (2D) wedge nozzles. Following our earlier work the equations governing the steady, inviscid, quasi-one-dimensional
flow in the wedge nozzle of thegdl are reduced to a universal form so that their solutions depend on a single unifying parameter. These equations are solved
numerically to obtain similar solutions for the various flow quantities, which variables are subsequently used to optimize
the small-signal-gain. The corresponding optimum values like reservoir pressure and temperature and 2D nozzle area ratio also
have been predicted and graphed for a wide range of laser gas compositions, with either H2O or He as the catalyst. A large number of graphs are presented which may be used to obtain the optimum values of small signal
gain for a wide range of laser compositions without further computations. 相似文献
619.
620.
F. Labaar 《International Journal of Infrared and Millimeter Waves》1984,5(2):123-133
A test method is described that uses the Delay Line Bridge (DLB) discriminator as a phase modulation (PM)- or amplitude modulation (AM) detector. A brief discussion is given to explain the different measurement requirements for pulsed sources used in Doppler RADAR with stationary or slow moving transmitter platforms, and fast moving transmitter platforms. A practical solution is offered to the problem of inadequate isolation in present day W-band PIN switches. This measurement set-up, provides a direct measure of the level of spurious oscillations of the IMPATT source, the relative noise content in the turn-on and turn-off region of the RF pulse, and the phase ripple. It also illustrates the influence of reference source injection locking level on the measured characteristics. 相似文献