一类新的关于(4+4+1)-体共轭套中心构型

本文研究R3中一类(4+4+1)-体中心构型.利用中心构型等价类的性质及代数、分析方法,得到了该构型构成中心构型的充分和必要条件,证明了对任意给定的质量比这类中心构型存在的结论,解决了给定不同质量比范围该类中心构型是否唯一的问题,推广了文[16]的结论.     

Crystal Structure of 9α,11-Epoxy-7α-(methoxycarbonyl)-3-oxo-17α-pregn-4-ene-21,17-carbolactone

Abstract  The title compound (common name eplerenone), C₂₄H₃₀O₆, is an aldosterone receptor antagonist. From the isopropyl acetate solution the compound crystallizes in monoclinic space group P 21 with a = 8.811(1) ?, b = 11.250(1) ?, c = 11.079(1) ?, β = 93.822(12)°, Z = 2. The molecule contains three six membered rings, two five membered rings and one three membered ring. Both five membered rings display envelope conformation, whereas three six membered rings show different conformation: chair, half-chair and envelope. In the crystal the eplerenone molecules link to one another via intermolecular weak C–H···O hydrogen bonding to form the smaller cavity of 12.0(1) ?³ between eplerenone molecules, no solvent molecule filled in this cavity. Index Abstract  In the title molecule three six-membered rings show different conformation. Weak C–H···O hydrogen bonding links adjacent molecules to form the small cavity 12.0(1) ?³, no solvent molecule filled in the cavity.      

Quantum states transfer between coupled fields

We study the exchange of states in coupled fields along their time evolution. The coupling is described by a quadratic form in terms of annihilation and creation operator in the field Hamiltonian. An analytical approach is employed to describe the time evolution of the field state in Fock's space and the conditions for an arbitrary initial states to be transferred with 100% fidelity is determined. We show that only for initial states C₀|0>+C_N|N>, this situation can occurs. The important |1〉↔|0〉 qubits transfer is a particular case of this transference of number state. The relation between the coupling constant and characteristic field frequencies for complete state transference is also determined.     

Influence of Cavity Decay on Phase Distribution and Rabi Flopping in Cavity QED

The quantum mechanical phase distribution and the quantum oscillations of population are studied for a cavity field togetherwith a driven classical field. The atom is sent through the cavity and driven by a classical field. Also the time evolution of the system including decay is obtained. The graph showing the Rabi oscillations for this system is changed into a bit pattern from the system without decay. The phase probability function is also affected due to the presence of cavity decay.     

Performance of a 80 W copper vapor laser with “alignment free” unstable CAT-EYE resonator and other configurations using intra-cavity apertures

Performance of a kinetically enhanced copper vapor laser (KE-CVL) with various stable/unstable “alignment free” CAT-EYE resonator configurations are presented here in this paper. The laser used in the experiment was a 45 mm bore (∼2 l discharge volume) kinetically enhanced copper vapor laser developed in our laboratory and capable of generating maximum power of ∼80 W (at ∼9.8 kHz). The efficiency of the laser was ∼1.4% and beam divergence of ∼3.5 mrad in a plane-plane standard multimode cavity. For the first time performance of unstable CAT-EYE resonator is demonstrated with a CVL/KE-CVL. On using unstable CAT-EYE resonator the divergence of the laser beam reduced to ∼0.22 mrad (∼20-fold reduction as compared to conventional plane-plane cavity), ∼40 W output power and with excellent misalignment tolerance. The laser output power was found to be within ∼5% drift/decline with misalignment angle of about 4 mrad between the mirrors. This is a significant improvement in comparison to standard conventional unstable resonator (M ∼ 50) CVL where ∼0.5 mrad divergence is achieved with power drift/decline of about 45% at ∼4 mrad misalignment angle.Off-axis unstable CAT-EYE unstable resonator was also demonstrated for the first time with further reduction in beam divergence to ∼0.13 mrad and with output power of ∼28 W. The misalignment tolerance was found to be highest in case of off-axis unstable CAT-EYE resonator with decline/drift in laser power of only ∼10% for misalignment angle as high as ∼8 mrad. Performance with intra-cavity apertures in plane-plane type CAT-EYE resonator for transverse mode control is also presented for the first time in CVLs. It is observed that the laser beam divergence reduces significantly to 1.25 mrad (a factor of 2) on using an aperture of ∼3.5 mm at the CAT-EYE reflector as compared to its normal (R = F = d) configuration without aperture. In case of stable CAT-EYE resonator the average beam divergence reduces from 8 mrad to 4 mrad (factor of 2) on using intra-cavity aperture of about 3 mm. It was also observed that high misalignment tolerance was retained on using intra-cavity apertures in almost all the CAT-EYE resonators. Use of intra-cavity mesh was also demonstrated for the first time with stable CAT-EYE resonator for improving the beam focus-ability. Average beam divergence was reduced by a factor of 2.5 (from 8 mrad to 3 mrad) on using intra-cavity mesh. These new configurations in CAT-EYE resonators in KE-CVLs are found to be effective in improving and controlling the laser beam divergence significantly with additional characteristic of high misalignment tolerance.     

Optimization of Circular Ring Microstrip Antenna Using Genetic Algorithm

Circular ring microstrip antennas have several interesting properties that make it attractive in wireless applications. Although several analysis techniques such as cavity model, generalized transmission line model, Fourier-Hankel transform domain and the method of matched asymptotic expansion have been studied by researchers, there is no efficient design tool that has been incorporated with a suitable optimization algorithm. In this paper, the cavity model analysis along with the genetic optimization algorithm is presented for the design of circular ring microstrip antennas. The method studied here is based on the well-known cavity model and the optimization of the dimensions and feed point location of the circular ring antenna is performed via the genetic optimization algorithm, to achieve an acceptable antenna operation around a desired resonance frequency. The antennas designed by this efficient design procedure were realized experimentally, and the results are compared. In addition, these results are also compared to the results obtained by the commercial electromagnetic simulation tool, the FEM based software, HFSS by ANSOFT.     

A High-Efficiency Second-Harmonic Gyrotron with a Depressed Collector

The gyrotron with an electrically insulated collector has been manufactured and tested. The 60% output efficiency is obtained for the Collector Potential Depression (CPD) operation regime. The results of the numerical simulation of the electron energy spectrum in the collector region of the second-harmonic technological 24 GHz gyrotron are presented. It is shown, that the minimal electron beam energy is about 20% of the initial value and that the gyrotron cavity should be expanded to achieve the highest output efficiency of the gyrotron with energy recovery. The highest experimental decelerating voltage is in good agreement with the calculation of the electron energy spectrum.     

Single quantum dot nanolaser

Recent theoretical and experimental progress on nanolasers is reviewed with a focus on the emission properties of devices operating with a few or even an individual semiconductor quantum dot as a gain medium. Concepts underlying the design and operation of these devices, microscopic models describing light‐matter interaction and semiconductor effects, as well as recent experimental results and lasing signatures are discussed. In particular, a critical review of the “self‐tuned gain” mechanism which gives rise to quantum‐dot mode coupling in the off‐resonant case is provided. Furthermore recent advances in the modeling of single quantum dot lasers beyond the artificial atom model are presented with a focus on the exploration of similarities and differences between the atomic and semiconductor systems.