High-l Rydberg States＇ Interference Using a Double-Pulse Electric Field

The interference behavior of high-1 Rydberg states is investigated in external fields. We prepare high-l states from an initial excited ns Cs Rydberg state by applying one electric-field pulse. The interference between the initial ns state and the high-I states is investigated by two time-delayed short electric-field pulses. The state selective field ionization technique is used to measure the transfer ratio versus the field pulses parameters. The visibility of interference is defined to describe interference and the results show that a relative long duration of electric-field pulse will weaken the interference.     

Total duration of negative surplus for a Brownian motion risk model with interest

In this paper,we consider the Brownian motion risk model with interest.The Laplace transform of the first exit time from the upper barrier before hitting the lower barrier is obtained.Using the obtained result and exploiting the limitation idea,we derive the Laplace transform of total duration of negative surplus.     

High-powered millijoule pulse energy Tm3＋-doped fiber amplifier at 2.05μm

A high-powered millijoule pulse energy Tm 3+ -doped fiber amplifier seeded with a Q-switched operation of Tm (4 at.-%), Ho (0.4 at.-%):YVO 4 laser is reported. The output characteristics of the amplified laser are studied at the coupled powers of 0.266, 1.24, and 2.65 W. Maximum output power up to 15.7 W is at 10-kHz repetition rate. Nonlinear effects are not observed from the emitting spectrum and the full-width at half-maximum (FWHM) of the pulse duration is reduced from 40.1 to 25.9 ns at 1.57-mJ pulse energy. The beam quality factor M 2 x = 1.9±0.03, M 2 y = 2.1±0.02 at the output power of 14.5 W is measured using the traveling knife-edge method.     

Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2-μm laser

We present a 3 5 μ m optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μ m laser. The tuning curves of ZGP OPO are calculated. The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7 4.6 μ m, is cut as θ =53.5°, φ =0°. When the pump power of 2.1-μ m polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μ m, respectively. Pulse duration is about 27 ns. Beam quality factor M 2 is better than 1.8. The tunability of 3 5 μ m can be achieved by changing the angle of the ZGP crystal.     

离散时间风险模型的递推公式

在本文中,我们研究了含有投资和通货膨胀因素的离散时间风险模型,通过递推的方法,得到了有限时间内的破产概率、破产时间的分布、破产持续时间的分布的递推公式.     

离散时间保险风险模型的破产问题

本文研究了引入利率的离散时间保险风险模型，得到了描述破产严重程度的破产前盈余分布、破产持续时间分布的递推公式，并对具体实例给出数值计算结果。     

Tunable femtosecond laser in the visible range with an intracavity frequency-doubled optical parametric oscillator

We demonstrated experimentally a synchronously pumped intracavity frequency-doubled femtosecond optical parametric oscillator (OPO) using a periodically-poled lithium niobate (PPLN) as the nonlinear material in combination with a lithium triborate (LBO) as the doubling crystal. A Kerr-lens-mode-locked (KLM) Ti:sapphire oscillator at the wavelength of 790 nm was used as the pump source, which was capable of generating pulses with a duration as short as 117 fs. A tunable femtosecond laser covering the 624-672 nm range was realized by conveniently adjusting the OPO cavity length. A maximum average output power of 260 mW in the visible range was obtained at the pump power of 2.2 W, with a typical pulse duration of 205 fs assuming a sech2 pulse profile.     

HEM11 mode magnetically insulated transmission line oscillator： Simulation and experiment

A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure. The special feature of such a device is that in the slow-wave-structure region, the interaction mode is HEM11 mode which is a TM-like one that could interact with electron beams effectively; and in the coaxial output region, the microwave mode is TE11 mode which has a favourable field density pattern to be directly radiated. Employing an electron beam of about 441 kV and 39.7 kA, the HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation. The power conversion efficiency is about 8.4 % and the generated microwave is in a TEll-like circular polarization mode. In a preliminary experiment investigation, high power microwave is detected from the device with a frequency of 1.46 GHz, an output energy of 43 J 47 J, and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV450 kV, and the diode current is 37 kA-39 kA.     

基于价格持续时间的中国股市日内风险价值预测

基于高频数据度量日内交易活动的风险是目前日内金融数据与风险管理中极具挑战性的研究课题之一。本文从实时交易的角度,使用中国股市分笔交易数据,基于价格持续时间的自回归条件持续时间(ACD)模型,研究日内不规则交易数据的风险测度,利用日内不等间隔波动模型估计了日内交易的即时条件波动率,对日内不等间隔风险价值进行了预测和检验。实证结果发现日内不等间隔风险价值模型能够比较好的刻画日内交易风险,股票投资者和市场监管者可以基于该工具对日内风险做出合理的预测,达到止损避险和控制风险的目的。     

航空复杂产品项目活动时间混合分布估算模型的改进

航空复杂产品开发项目具有复杂性、随机性、多目标性的特点,并且产品本身小批量、多品种的生产模式使得无法大量积累历史数据。因此,航空复杂产品项目活动时间存在高度的不确定性。如何能够更加合理、准确的描述其项目活动时间,对优化航空复杂产品的研制过程、缩短研制周期以及降低研制成本具有重大的意义。本文在Hahn基于PERT所建立的Beta Rectangular混合分布模型的基础上,保留其期望值的表达式,对其方差表达式进行改进。按照Malcolm、José等人的思想,将最可能值m与Beta分布的众数相对应,并且考虑其对方差的影响。仅保留PERT的一个假设,使方差的推导更多地依照于Beta分布而不是较多的近似。仿真结果表明,改进后的混合分布模型不但更具柔性,而且可以更加科学准确地描述航空复杂产品调度中高度不确定的任务持续时间状况。