复合多层介质在可变温度和集中荷载作用下的位移和应力

研究了多层介质中的热弹性位移和应力.多层介质具有不同厚度,各层又具有不同的弹性性质,最上层表面上作用热荷载和集中荷载.假设各层分别是均匀、各向同性弹性材料,各层相关的位移分量是轴对称的,对称轴为各层表面的垂线.因此,各层应力函数满足无体力的单一方程.利用积分变换法求解了该方程,对由任意多个层数构造的多层介质,给出了其相应层数基础热弹性位移和应力的解析表达式.并对3层介质和4层介质时的数值结果进行了比较.     

On the notion of control signals in digital designs

The concept of control signals is fundamental to digital design. It evokes the notion of one or more signals that influence computation on other signals in a system, and regulate the behavior of the system. A formal definition of control signals is presented. It is argued that knowledge of the control signals in a complex design such as a microprocessor or a computer is crucial to the comprehension and specification of the design and that knowledge of the control signals of a design leads to a more efficient hardware implementation. The identification of control signals in two microprocessors are presented as examples     

Energy crisis or a new soliton in the noncommutative CP(1) model?

The non-commutative (NC) CP(1) model is studied from field theory perspective. Our formalism and definition of the NC CP(1) model differs crucially from the existing one [Phys. Lett. B 498 (2001) 277, hep-th/0203125, hep-th/0303090].

Due to the U(1) gauge invariance, the Seiberg–Witten map is used to convert the NC action to an action in terms of ordinary spacetime degrees of freedom and the subsequent theory is studied. The NC effects appear as (NC parameter) θ-dependent interaction terms. The expressions for static energy, obtained from both the symmetric and canonical forms of the energy momentum tensor, are identical, when only spatial noncommutativity is present. Bogomolny analysis reveals a lower bound in the energy in an unambiguous way, suggesting the presence of a new soliton. However, the BPS equations saturating the bound are not compatible to the full variational equation of motion. This indicates that the definitions of the energy momentum tensor for this particular NC theory (the NC theory is otherwise consistent and well defined), are inadequate, thus leading to the “energy crisis”.

A collective coordinate analysis corroborates the above observations. It also shows that the above mentioned mismatch between the BPS equations and the variational equation of motion is small.     

Coupled channel description of O+Nd scattering around the Coulomb barrier using a complex microscopic potential

Angular distributions of elastic scattering and inelastic scattering from 2⁺₁ state are measured for ¹⁶O+^142,144,146Nd systems at several energies in the vicinity of the Coulomb barrier. The angular distributions are systematically analyzed in coupled channel framework. Renormalized double folded real optical and coupling potentials with DDM3Y interaction have been used in the calculation. Relevant nuclear densities needed to generate the potentials are derived from shell model wavefunctions. A truncated shell model calculation has been performed and the calculated energy levels are compared with the experimental ones. To simulate the absorption, a ‘hybrid’ approach is adopted. The contribution to the imaginary potential of couplings to the inelastic channels, other than the 2⁺₁ target excitation channel, is calculated in the Feshbach formalism. This calculated imaginary potential along with a short ranged volume Woods–Saxon potential to simulate the absorption in fusion channel reproduces the angular distributions for ¹⁶O+¹⁴⁶Nd quite well. But for ¹⁶O+^142,144Nd systems additional surface absorption is found to be necessary to fit the angular distribution data. The variations of this additional absorption term with incident energy and the mass of the target are explored.     

Buckling of laminated plates - A simple finite element based on higher-order theory

A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates.     

Effect of the three-body force on triton asymptotic normalization constants by the hyperspherical harmonics expansion method

We investigate the change in the calculated value of asymptotic normalization constant (ANC) by the hyperspherical harmonics expansion method with the inclusion of three nucleon force (3BF) in addition to two nucleon force. We see that ANC does not change very much with the inclusion of 3BF indicating that the 3BF does not alter the asymptotic behaviours of HHE wavefunction significantly.     

Are the proposed cosmic H particles psionlike in Nature?

Summary The hints to explain the unusual type of cosmic cluster events (called generally the ?exotic? events) in ultrahigh-energy nuclear collisions in terms of proposed H particles have, to date, been neither substantiated nor concretised. We assort here some crucial aspects and assemble a few supportive evidences to favour our idea that the proposed H particles might be viewed as cosmic psionlike particles.     

Excess noise generation during spectral broadening in a microstructured fiber

We observe that nanojoule femtosecond pulses that are spectrally broadened in a microstructured fiber acquire excess noise. The excess noise is manifested as an increase in the noise floor of the rf spectrum of the photocurrent from a photodetector illuminated by the pulse train from the laser oscillator. Measurements are made of the intensity dependence of the excess noise for both 100 fs and sub-10 fs pulses. The excess noise is very strong for 100 fs pulses, but barely measurable for sub-10 fs pulses. A rigorous quantum treatment of the nonlinear propagation of ultrashort pulses predicts that, for a fixed generated bandwidth, the amount of excess noise decreases with pulse duration, in agreement with the experimental results.