关于N-Si:Pd中能级E(0.37)和E(0.62)的识别

在已证实Si中与间隙Pd有关的E_(TA)(0.37)和E_(TB)(0.62)能级为同一双施主中心的(0/ +)态与(+/++)态的基础上,本文通过一系列实验事实进一步揭示该中心是有B杂质参与的络合物.     

确定聚类数目的一个准则

Aiming to provide an appropriate number K of clusters, in this paper, we propose a new criterion function - H criterion function, whose three properties have also been proved. We validate the performance of the H criterion function on one artificial dataset and three real-world datasets, and the results are almostly consistent with a previous method. The nonparametric criterion we proposed is intuitive, simple and the computational cost is acceptable.     

秩函数与K0群的状态空间

给出了局部秩与稳定自由秩的表达式,得到了一类VN正则环的元素特征.利用K0群的状态空间,给出了K0R有关性态的本质刻画.     

强电子束泵浦的CW Ar^＋激光

电子束泵浦的离子激光器，由于其高密度的高能电子具有增加效率、功率和在真空紫外区域产生CW辐射的可能。对于离子激光器，控制高密度束电子的能量，使其处于激光上能级的大激发截面区域是非常重要的。     

基于数学模型的通信数据加密保护系统设计

通信数据在传输过程中,由于受到通信环境噪声以及非法攻击者的攻击影响,使得通信数据容量值降低,用户隐私数据安全受到严重威胁。针对这一问题,在引入数学模型的基础上,开展通信数据加密保护系统设计研究。通过通信传输设备选型、通信连接服务器选型等硬件设计和基于数学模型的通信数据系统加权处理、基于非法攻击者的通信信道盲符号引入、基于通信终端用户的通信数据加密和周期性更换通信数据加密保护密钥等软件设计,提出一种全新的加密保护系统。通过实验证明,新的加密保护系统在实际应用中可有效提高通信数据加密保护的容量值,确保通信数据的安全传输。     

MMDS在乡村有线电视系统中的应用

黑龙江省绥滨县地处东北三江平原 ,地域开阔 ,县中心距离富锦市距离不到 10ｋｍ ,全县共有 11个乡镇 ,有大到几百户 ,小到几十户的 16 7个自然村屯。乡村有线电视 ,在这个十几万人的小县起步较晚 ,但从1997年年初开通ＭＭＤＳ以后 ,乡村有线电视发展迅速。现已开通近 110个村屯 ,入户 1万多户。1　普及绥滨县乡村有线电视的总体思路乡村有线电视的普及 ,是广播电视事业全面发展的象征 ,是必然趋势。它能更好地以电视为媒介 ,宣传党的方针政策 ,丰富农村的业余文化生活 ,有非常可观的社会效益与经济效益。有线电视要实现县乡联网 ,如果用电缆…     

电子商务与现代企业

电子商务的发展改变了传统的生产、营销、交易和消费模式，给现代企业的经营带来了影响。现代企业必须应用电子商务技术，调整自己的营销策略，开拓更大的市场空间，促进企业的发展。     

Nonlinear spectroscopy of three-photon excitation of cesium Rydberg atoms in vapor cell

We present nonlinear spectra of four-level ladder cesium atoms employing 6 S1/2→6 P3/2→7 S1/2→30 P3/2 scheme of a room temperature vapor cell.A coupling laser drives Rydberg transition,a dressing laser couples two intermediate levels,and a probe laser optically probes the nonlinear spectra via electromagnetically induced transparency(EIT).Nonlinear spectra are detected as a function of coupling laser frequency.The observed spectra exhibit an enhanced absorption(EA) signal at coupling laser resonance to Rydberg transition and enhanced transmission(ET) signals at detunings to the transition.We define the enhanced absorption(transmission) strength,HEA(HET),and distance between two ET peaks,γET,to describe the spectral feature of the four-level atoms.The enhanced absorption signal HEA is found to have a maximum value when we vary the dressing laser Rabi frequency Ωd,corresponding Rabi frequency is defined as a separatrix point,ΩdSe.The values of ΩdSe and further η=ΩdSe/Ωc are found to depend on the probe and coupling Rabi frequency but not the atomic density.Based on ΩdSe,the spectra can be separated into two regimes,weak and strong dressing ranges,Ωd≤ΩdSe and Ωd≥QdSe,respectively.The spectroscopies display different features at these two regimes.A four-level theoretical model is developed that agrees well with the experimental results in terms of the probe-beam absorption behavior of Rabi frequency-dependent dressed states.