New exact solutions for fluid transients

New exact solutions for damped fluid transients are reported. Complicated excitations are easily accommodated. Some interesting special cases are discussed in detail.     

Scalar Conservation Laws and Spatially Dependent Flux Functions

In this paper, we carry out a detailed analysis of the signaling and initial value problems associated with a general scalar conservation law that admits spatial variation in the flux function. The approach adopted here is to introduce a nonlinear phase variable directly into the problem and carry out the analysis in the space and phase variables rather than in space-time. This facilitates our efforts to create, through a bifurcation analysis, a clear picture of the process by which a smooth wave breaks to generate a propagating shock wave.     

Two-way transmission at 2.488 Gbit/s over a 132 km operational submerged cable using erbium-doped fibre power amplifiers

The results of a field trial on the UK-Channel Islands No.7 cable, in which ruggedised, broadband erbium power amplifiers were used to achieve two-way transmission at 2.488 Gbit/s over a 132 km submerged cable is reported.<>     

Study of density and potential fluctuations in the TEXT tokamakwith a heavy ion beam probe

A heavy ion beam probe was used to study the characteristics of density and potential fluctuations in the TEXT tokamak. Fluctuations of density and space potential are nearly Boltzmann like, n˜/n~φ˜/kT_e, near the edge of the plasma (0.80.9). The turbulent E&oarr;×B&oarr; radial particle flux is sufficient to account for all of the particle loss from the tokamak. No poloidal asymmetries, within a poloidal angle range of about 70°, are observed in the fluctuation levels. The fluctuation spectral shape, the density potential phase angle, and the fluctuation propagation speed show a strong radial dependence     

Asymptotic Analysis of a Nonlinear Problem in Thermoelasticity

In this paper we employ our previously formulated constitutive relations for an elastic heat conductor to examine the nonlinear influence of the temperature on the propagation of second sound. Utilizing the method of geometric optics we ascertain that large values of second sound travel more slowly than do smaller ones. As well, numerical results for a signaling problem are displayed graphically in order to highlight the qualitative properties of the temperature and strain waves. The choice of signaling data was motivated by experimental studies.     

Laboratoriumsapparate

Ohne Zusammenfassung     

Torsional-mode transients in variable-thickness shells of revolution

For thin shells of revolution the existence of torsional-vibration modes, uncoupled from bending and extensional modes, has been established[1]. Here a linear second-order differential equation for the uncoupled torsional stress mode is obtained and its solution for impact loading of shells is sought. The mode-superposition method which utilizes the natural modes of vibration predicted by elementary theory, is, in general, not satisfactory for sharp impact loading as many modes are often required for convergence. Hence we employ two novel techniques for solving the impact problems. Firstly a formal asymptotic procedure, based on extensions to geometrical optics, is employed to generate asymptotic wavefront expansions. Rigorous justifications for this formal technique are provided in an appendix. Secondly a transform technique whereby solutions are sought in terms of Bessel functions is discussed and applied to particular impact loading problems. The Bessel function solutions found here can be used to determine the natural frequencies of the shells. Shells both finite and infinite in extent are discussed and reflections at a stress-free end are examined.