用信号处理技术及传播理论还原雷声频谱

以往关于雷声的研究都限于观测点雷声频域范围的探讨, 由于噪音和衰减因素的影响, 观测点的雷声频谱有很大失真. 针对在兰州地区观测的一次雷暴过程中的雷声信号, 利用数字信号处理技术,由观测点处的雷声音频信号得到频率谱,并对雷声频谱进行噪音分析; 然后结合声音在大气中传播的衰减理论, 分析了不同大气环境对声吸收的影响, 并推算出了声源附近的雷声频率谱. 关键词： 雷声频谱 信号处理 传播理论 峰值频率     

甘氨酸色氨酸寡肽链的红外光谱的密度泛函研究

运用密度泛函理论, 在6-31 G(d) 基组水平上对甘氨酸色氨酸交替组成的六种寡肽链结构进行几何优化, 并进行了结合能和振动光谱地分析. 结果表明, 寡肽的生长利于结构的稳定性. 随着肽链的生长, 单一基团的振动存在蓝移或奇偶震荡现象; 同类官能团的耦合振动存在红移现象; 而肽链端部基团的振动频率基本不变. 这些丰富的频移现象和尺寸效应、耦合效应、诱导效应、奇偶效应等因素共同竞争有关. 该结果对应用红外光谱对寡肽链的残基数及长度地测量等工作有指导意义. 关键词： 寡肽链 红外光谱 耦合效应 尺寸效应     

正交多载波M元循环移位键控扩频水声通信

针对水声扩频通信中频带利用率低的问题, 提出了一种M元扩频技术和循环移位键控(CSK)技术相结合的多载波调制方式, 将M元扩频后选择的扩频码同时采用CSK调制, 并调制在多个正交的载波上, 显著提高了频带利用率. 在水声多途信道下, 采用相同的通信速率和带宽, m序列、Kasami小集合序列和Gold序列为扩频码时, 比较了系统的误码性能. 仿真结果和实验结果均表明, m序列为扩频码时性能最优, Gold序列性能最差. 由于m序列数量有限, 为了进一步提高通信速率, 并使其他序列的性能接近m序列性能, 提出了一种复合序列抑制载波间干扰的算法, 该算法能够很好抑制多途干扰, 使复合序列性能接近m序列的性能. 关键词： M元扩频')" href="#">M元扩频 循环移位键控 正交多载波 载波间干扰     

Infrared and Raman Spectra for Amino Group and C˭O Stretching Modes in Biomolecule 5‐Aminouracil

Abstract

Assuming planar geometry of 5‐aminouracil and C_s point group symmetry, it has been possible to assign all the 36 (25a′+11a″) normal modes of vibration. The two NH bonds of the NH₂ group appear to be non-equivalent as the NH₂ stretching frequencies and do not satisfy the empirical relation proposed for the two equivalent NH bonds of the NH₂ group due to their involvement and interaction with one hydrogen bond and the other adjacent oxygen atom of the parent molecule. The planar and nonplanar bending modes due to the C₄?O₈ bond are expected with have lower magnitude compared with those due to the C₂?O₇ bond.     

Luminescence of Cs2PtF6

In the past five years, a number of d⁶ complexes have been found to exhibit luminescence when excited by ultraviolet light. Such emission has been assigned to d-d transitions localized on the metal ion, to charge-transfer transitions, and to ligand localized transitions^2,3. The specific kind of emission observed is thought to depend on which electronic level lies lowest in energy.     

Interpretation of Polarized Absorption and Emission Spectra of Molecules Incorporated in Stretched Polymer Films

Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented.     

Spectra Studies of Complexes Between Palladium (II), Nickel (II) and Amino Acids

The complexes of Ni (His) 2·H2O, Ni (Gly) 2·2H2O, Pd (His)Cl2·H2O and Pd(Gly) 2·2H2O were synthesized. And the IR, electronic absorption and photoacoustic spectra of these complexes were measured in solid state. The nature of the metal-carboxylate coordinate bond were deduced from the variation in the carboxyl stretching frequencies. And the d-d transition absorptions of these complexes were interpreted quantitatively with the 3d scaling radial theory. Therefore, the structural characterizations were also discussed with their spectral behaviors.     

Effects of the primary recoil spectrum on long-range migration of defects

Abstract

For quantitative predictions and comparisons of microstructures that evolve during exposure to different radiation environments at elevated temperature one needs to develop methods that go beyond those based on the number of displacements per atom. The number of freely migrating defects that contribute to the microstructural development is far less than the total number of defects produced, as has been recognized for some time from measurements of radiation-induced segregation and of radiation-enhanced diffusion. Defect production in various neutron and ion irradiation environments is discussed in light of this fact. A method to calculate the fraction of freely migrating defects from the cluster size distribution of defects produced in cascades is suggested. The results are in good agreement with available data.     

Mass extrapolation of quarks and leptons to higher generations

An empirical mass formula is tested for the basic fermion sequences of charged quarks and leptons. This relation is a generalization of Barut’s mass formula for the lepton sequence (e, μ, τ......). It is found that successful mass extrapolation to the third and possibly to other higher generations (N>2) can be obtained with the first and second generation masses as inputs, which predicts the top quark massm _t to be around 20 GeV. This also leads to the mass ratios between members of two different sequences (i) and (i′) corresponding to the same higher generations (N>2).     

ON THE ESSENTIAL SPECTRUM OF PSEUDODIFFERENTIAL OPERATORS （Ⅱ）

This paper coutinues the studies of the essential spectrum of nonsemi-bounded pseudodifferential operators. The author improves the results in [5] in some sense. For the relativistic Schrodinger operator,√(-Δ+m^2)+v(x),complete results are obtained.