RITZ VECTOR APPROACH FOR STATIC AND DYNAMIC ANALYSIS OF PLATES WITH EDGE BEAMS

A Ritz vector approach is used to develop new formulations for evaluating the static and the dynamic characteristics of rectangular plates with edge beams. Unlike previous studies in which stiffness coefficients with specified distributions along the plate edges are used to represent the effect of edge restraints, the effect of elastic edge restraints is accounted for by including appropriate integrals for edge beams in the expressions for total kinetic and potential energies in a Rayleigh-Ritz approach. The effect of various types of boundary conditions at the beam ends is accounted for by considering the corresponding Ritz vectors. The contribution of beam mass to the total kinetic energy is also considered in the proposed approach. This effect has often been neglected in the previous studies but can be significant in some applications. The results obtained from the application of the proposed approach to a variety of examples are compared with the corresponding results obtained from the finite element analysis.     

Analysis of a centre-driven antiphase dipole in a warm plasma†

The radiation properties of a thin dipole in a warm plasma, fed with currents in opposite phase, have been theoretically investigated using linearized hydrodynamic theory. Expressions for the far-zone electromagnetic and electroacoustie fields are derived in terms of general propagation constant β. The values of fields and of the radiation resistance are computed using β = β_e and compared with those of a standard dipole. It is found that tho eradiation of the electromagnetic mode is partially suppressed, whereas that of plasma mode remains almost unaltered, suggesting that the antenna could be used for launching electroacoustic waves.     

Drift wave in pair-ion plasma

The conditions for the existence of low-frequency electrostatic drift wave in pair-ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.     

Optical probing of Eu ions confined in an RF trap

The Eu ions confined in an RF quadrupole trap, has been optically detected. Using a tunable dye laser which is pumped by a Nd-YAG pulsed laser system, the resonance ⁹S₄^9S_4–6p _3/2, J = 5 transition of the Eu ions have been excited and the resulting fluorescence to the metastable ⁹D_4-6^9D_{4-6} state has been detected. In preparation to determine the ground-state hyperfine splitting of the odd isotopes we found the optimum trapping operating point. We have also observed a number of instabilities inside the region of the stability for an ideal trap. These non-linear resonances arise from higher-order contributions to the ideal quadrupole potential.     

Single-stage amplifier characteristics of the super-beta composite transistor†

A study has been made of the single-stage amplifier characteristics of the super-beta composite transistor system, in which the circuit has been analysed and the expressions for its voltage gain, current gain, input resistance and the power gain have been obtained in terms of the various parameters of the individual transistor. Further, the expressions obtained have been simplified by taking similar transistors of the composite system. The variations of input resistance, current gain and the power gain with load resistance have also been studied and a set of curves is given showing these variations.     

Excitation of Bulk-wave on Columns of Magnetized Plasma†

The excitation of the bulk-wave mode on a column of magnetized plasma by a ring of magnetic current outside the plasma is studied. The analysis is based on a solution of the inhomogeneous wave equation by the method of Fourier transforms. It is shown that slow waves with a large E _s field on the axis can be excited with high excitation efficiency.     

当方差未知时选取有最大均值总体的两阶段抽样方案

考虑ｋ个有连续分布Ｆｉ＝Ｆ（ｘ－μｉ／σ）的总体，ｉ＝１，．．．，ｋ。其中μｉ和σ均未知，我们通过两阶段抽取样本以得到最大均值的那个总体，第一步根据抽样删去一部分看来不可能的总体，第二步再从余下总体中抽样，取含样本均值最大的那个总体为所需总体，我们用渐过分布方法得到了在所定规则下能选到正确总体的概率下界。特别对Ｌｏｇｉｓｔｉｃ总体计算了有关数值以及关于一次抽样的相对效。     

A Method for Solving Moving Boundary Problems in Heat Flow using Cubic Splines or Polynomials

A new approach to a heat-flow problem involving a moving boundarymakes use of a grid system which moves with the boundary. Twovariations of the method are described. In the first, necessaryinterpolations are performed by using cubic splines; in thesecond, cubic polynomials are employed. The method smooths outirregularities in the motion of the boundary which were evidentin previous calculations based on a fixed grid system.     

Dynamical after-effects of nuclear decay in Mössbauer resonance

A general expression has been derived for the spectral distribution of Mössbauer radiation in presence of both lattice dynamical and electronic aftereffects of nuclear decay. The expression has been used to calculate Mössbauer spectrum in a possible experimental situation where the decaying atomic state results in a change in hyperfine interactions as well as a change in the binding of the Mössbauer atom in the lattice.     

Spectroscopy and laser characterization of synthesized supramolecular host cucurbit[7]uril using aqueous Rhodamine B dye

Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbit[7]uril (CB[7]), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB[7] in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5–7) with CB[7] as the minor product. The literature procedure has been optimized to get pure CB[7] in 12–14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB[7] sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.