静子尾缘喷气后尾迹与动叶干涉噪声研究

尾缘喷气技术已经广泛地用于航空发动机和多级压缩机等领域,用以降低动静叶片间的相互干涉作用以提高透平机械的气动性能,并降低动静干涉噪声.本文对尾缘喷气用于低压轴流风机进行了详细的研究,对轴流风机的上游静叶实施尾缘喷气,通过实验测量,尾缘喷气使静叶尾迹达到无动量亏损尾迹状态能够降低风机噪声,文章还提出了基于CFD数值模拟的尾迹与动叶相互干涉的噪声预测模型,预测结果和实验结果比较接近.     

Model Potential Calculations of Oscillator Strength Spectra of Rydberg Li Atoms in External Fields

By combining the B-spline basis set with model potential （B-spline ＋ MP）, we present oscillator strength spectra of Rydberg Li atoms in external fields. The photoabsorption spectra are analyzed. Over the narrow energy ranges considered in this paper, the structure of the spectra can be independent of the initial state chosen for a given atom. Our results are in good agreement with previous high-precision experimental data and theoretical calculations, where the R-matrix approach together with multichannel quantum defect theory （R-matrix＋MQDT） was used. It is suggested that the present methods can be applied to deal with the oscillator strength spectra of Rydberg atoms in crossed electric and magnetic fields.     

$J^{P}$ Assignments of $\Lambda_c^{+}$ Baryons

The ＂good＂ diquark is employed to study A＋ baryons within a mass loaded flux tube model. The study indicates that all A＋ baryons candidates in the 2008 review by the Particle Data Group （PDG） are well described in the mass loaded flux model. The quantum numbers JP of these A＋ candidates are assigned. If Ac（2765）＋ is an orbitally excited A＋, it is likely the JP=3/2＋one. If ∧c（2765）＋ is an orbitally excited ∑c, there ought to be another JP=3/2＋∧c＋with mass ≈2770 MeV. In the model, there exists no JP=1/2＋∧c＋（≈2700）predicted in existing literature. Ac （2940）＋ is very possible the orbitally excited baryon with     

Coherent Control of Population Transfer in Li Atoms via Chirped Microwave Pulses

We demonstrate theoretically that Li atoms can be transferred to states of a lower principal quantum number by exposing them to a frequency chirped microwave pulse. The population transfer of Li atoms from the n = 75 state to n = 70 with more than 90% efficiency is achieved by means of the sequential single-photon △n = -1 transitions. The calculation fully utilizes all of the available orbital angular momentum l states for a given n, and the interference pattern and population evolution dynamics of individual l states are analyzed in detail. Using the time-dependent multilevel approach, we describe the process reasonably well as a sequence of adiabatic rapid passages.     

Momentum transfer dependence behaviors of ionization and dissociation of oxygen

The decay pathways of the structured ionization region of oxygen at different momentum transfers,i.e.,0,0.23 a.u.(atomic unit),and 0.91 a.u.,are studied by measuring the ion and the scattered electron coincidently.It is found that the dipole-forbidden superexcited states of(2σu)-1(c4Σu-)npσu 3Σg-← X3Σg-decay into different channels according to the principal quantum number n.The broad ridge above 35 eV,which may be due to inner-valence excited states of(2σg)-1nλ or multiply excited states,is observed both at small and large momentum transfers,and its decay channel of O++ O is dominant.     

Exact quantum defect theory approach for lithium in magnetic fields

We calculate the diamagnetic spectrum of lithium at highly excited states up to the positive energy range using the exact quantum defect theory approach. The concerned excitation is one-photon transition from the ground state 2s to the highly excited states np with π and σ polarizations respectively. Lithium has a small quantum defect value 0.05 for the np states, and its diamagnetic spectrum is very similar to that of hydrogen in the energy range approaching the ionization limit. However, a careful calculation shows that the spectrum has a significant discrepancy with that of hydrogen when the energy is lower than 70cm-1 . The effect of the quantum defect is also discussed for the Stark spectrum. It is found that the σ transition to the np states in an electric field has a similar behavior to that of hydrogen due to zero interaction with channel ns.     

Cr~(21+)离子1s~23d-1s~2nf的跃迁能和偶极振子强度(英文)

用全实加关联方法计算了类锂Cr21+离子1s23d-1s2nf(4≤n≤9)的跃迁能和1s2nf(n≤9)态的精细结构.在类氢近似下估算了对能量的高阶相对论修正.依据量子亏损理论,确定了Rydberg系列1s2nf的量子数亏损.据此可以实现对任意高激发态(n≥10)的能量的可靠预言.计算了Cr21+离子1s23d-1s2nf(4≤n≤9)跃迁的振子强度.与量子亏损理论相结合,得到该离子从1s23d态到电离阈附近高激发束缚态间的偶极跃迁振子强度以及到相应连续态跃迁的振子强度密度,从而将Cr21+离子的这一重     

Fe~(16+)(1s~22s~22p~6)辐射复合截面的相对论理论研究

利用Dirac-Slater相对论平均自洽场理论,研究了类氖铁离子Fe16+(1s22s22p6)与自由电子的辐射复合(RR)截面,在分析相对论量子数的取值范围及原子模型等对n壳层RR截面的影响的基础上,给出了n壳层RR截面随自由电子能量变化的一般规律.     

Mn22+离子1s23d1s2nf的跃迁能和振子强度

用全实加关联方法计算了类锂Mn22 离子1s23d-1s2nf(4≤n≤9)的跃迁能和1s2nf(n≤9)态的精细结构,在类氢近似下估算了对能量的高阶相对论修正.依据量子亏损理论,确定了Rydberg系列1s2nf的量子数亏损,据此可以实现对任意高激发态(n≥10)的能量的可靠预言.计算了Mn22 离子1s23d-1s2nf(4≤n≤9)偶极跃迁的振子强度.     

最弱受约束电子势模型下Fe ΧⅥ离子Rydberg态能级的研究

在最弱受约束电子势模型的理论框架下,通过对最弱受约束电子的识别,将Martin关于单价原子量子亏损公式推广到多价原子(离子)系统,从而计算了Fe ΧⅥ离子的2p6np2P°1/2,3/2(n≥3)和2p6nd2D3/2,5/2(n≥3)系列Rydberg态的能级,理论计算值与实验值符合很好,两者的相对误差不超过3.02×10-5,达到了很高的精度.