Application of quasi-homogeneous anisotropic laminates in grid-stiffened panel design

Composite laminates are derived for standard configurations with quasi-homogeneous anisotropic properties, whereby in-plane and out-of-plane stiffness properties are concomitant. Dimensionless parameters, and their relationship to the well-known ply- orientation-dependent lamination parameters, are also developed from which the elements of the extensional and bending stiffness matrices are readily calculated for any fiber/resin properties. The definitive list of laminate configurations for up to 21 plies is presented, together with graphical representations of the lamination parameter design space for standard ply orientations +45, -45, 0 and 90 degrees. Finally, the potential of quasi-homogeneous anisotropic laminates as an optimum design solution for anisogid structures is explored for cases where buckling and strength constraints are both active

Energy and Momentum of Oscillating Neutrinos

It is shown that Lorentz invariance implies that in general flavor neutrinos in oscillation experiments are superpositions of massive neutrinos with different energies and different momenta. It is also shown that for each process in which neutrinos are produced there is either a Lorentz frame in which all massive neutrinos have the same energy or a Lorentz frame in which all massive neutrinos have the same momentum. In the case of neutrinos produced in two-body decay processes, there is a Lorentz frame in which all massive neutrinos have the same energy.Comment: 6 pages, no figure

Global Seismic Oscillations in Soft Gamma Repeaters

There is evidence that soft gamma repeaters (SGRs) are neutron stars which experience frequent starquakes, possibly driven by an evolving, ultra-strong magnetic field. The empirical power-law distribution of SGR burst energies, analogous to the Gutenberg-Richter law for earthquakes, exhibits a turn-over at high energies consistent with a global limit on the crust fracture size. With such large starquakes occurring, the significant excitation of global seismic oscillations (GSOs) seems likely. Moreover, GSOs may be self-exciting in a stellar crust that is strained by many, randomly-oriented stresses. We explain why low-order toroidal modes, which preserve the shape of the star and have observable frequencies as low as ~ 30 Hz, may be especially susceptible to excitation. We estimate the eigenfrequencies as a function of stellar mass and radius, and their magnetic and rotational shiftings/splittings. We also describes ways in which these modes might be detected and damped. There is marginal evidence for 23 ms oscillations in the hard initial pulse of the 1979 March 5th event. This could be due to the $_3t_0$ mode in a neutron star with B ~ 10^{14} G or less; or it could be the fundamental toroidal mode if the field in the deep crust of SGR 0526-66 is ~ 4 X 10^{15} G, in agreement with other evidence. If confirmed, GSOs would give corroborating evidence for crust-fracturing magnetic fields in SGRs: B >~ 10^{14} G.Comment: 12 pages, AASTeX, no figures. Accepted for Astrophysical Journal Letter

Compensation of pulse-rebalanced inertial instruments

Study explains the basic concept of pulse-rebalanced inertial instruments in terms of an idealized model which performs the processes of integration, prediction and quantization. An analytical model of an actual pulse-rebalanced instrument was derived in a form comparable to the idealized system

Elements of orbit-determination theory - Textbook

Text applies to solution of various optimization problems. Concepts are logically introduced and refinements and complexities for computerized numerical solutions are avoided. Specific topics and essential equivalence of several different approaches to various aspects of the problem are given