Gamma-ray and X-ray luminosities from spin-powered pulsars in the full polar cap cascade model

We modify the conventional curvature radiation (inverse Compton scattering) + synchrotron radiation polar cap cascade model by including the inverse Compton scattering of the higher generation pairs. Within the framework of the space-charge-limited-flow acceleration model with frame-dragging proposed by Harding & Muslimov (1998), such a full polar cap cascade scenario can well reproduce the $L_\gamma \propto (L_{\rm sd})^{1/2}$ and the $L_x \sim 10^{-3} L_{\rm sd}$ dependences observed from the known spin-powered pulsars. According to this model, the ``pulsed'' soft ROSAT-band X-rays from most of the millisecond pulsars might be of thermal origin, if there are no strong multipole magnetic components near their surfaces.Comment: To appear in Proc. 5th Compton Symposium, Portsmouth, New Hampshire, concise version of the ApJ pape

Coherent states engineering with linear optics: Possible and impossible tasks

The general transformation of the product of coherent states $\prod_{i=1}^N|\alpha_i>$ to the output state $\prod_{i=1}^M|\beta_i>$ ($N=M$ or $N\neq M$), which is realizable with linear optical circuit, is characterized with a linear map from the vector $(\alpha^{\ast}_1,...,\alpha^{\ast}_N)$ to $(\beta^{\ast}_1,...,\beta^{\ast}_M)$. A correspondence between the transformations of a product of coherent states and those of a single photon state is established with such linear maps. It is convenient to apply this linear transformation method to design any linear optical scheme working with coherent states. The examples include message encoding and quantum database searching. The limitation of manipulating entangled coherent states with linear optics is also discussed.Comment: 6 pages, 2 figure

Off-Beam Gamma-Ray Pulsars and Unidentified EGRET Sources in the Gould Belt

We investigate whether gamma-ray pulsars viewed at a large angle to the neutron star magnetic pole could contribute to the new population of galactic unidentified EGRET sources associated with the Gould Belt. The faint, soft nature of these sources is distinctly different from both the properties of unidentified EGRET sources along the galactic plane and of the known gamma-ray pulsars. We explore the possibility, within the polar cap model, that some of these sources are emission from pulsars seen at lines of sight that miss both the bright gamma-ray cone beams and the radio beam. The off-beam gamma-rays come from high-altitude curvature emission of primary particles, are radiated over a large solid angle and have a much softer spectrum than that of the main beams. We estimate that the detectability of such off-beam emission is about a factor of 4-5 higher than that of the on-beam emission. At least some of the radio-quiet Gould Belt sources detected by EGRET could therefore be such off-beam gamma-ray pulsars. GLAST should be able to detect pulsations in most of these sources.Comment: 5 pages, uses emulateapj.sty, accepted for publication in ApJ Letter

Microscopic description of octupole shape-phase transitions in light actinides and rare-earth nuclei

A systematic analysis of low-lying quadrupole and octupole collective states is presented, based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the $sdf$ interacting boson model (IBM), that is, onto the energy expectation value in the boson condensate state, the Hamiltonian parameters are determined. The study is based on the global relativistic energy density functional DD-PC1. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in four isotopic chains characteristic for two regions of octupole deformation and collectivity: Th, Ra, Sm and Ba. Consistent with the empirical trend, the microscopic calculation based on the systematics of $\beta_{2}$-$\beta_{3}$ energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition between stable octupole deformation and octupole vibrations characteristic for $\beta_{3}$-soft potentials.Comment: 18 pages, 18 figures, 1 tabl

Adaptive and Robust Fault-Tolerant Tracking Control of Contact force of Pantograph-Catenary for High-Speed Trains

Abstract This paper presents a modified multi-body dynamic model and a linear time-invariant model with actuator faults (loss of effectiveness faults, bias faults) and matched and unmatched uncertainties. Based on the fault model, a class of adaptive and robust tracking controllers are proposed which are adjusted online to tolerate the time-varying loss of effectiveness faults and bias faults, and compensate matched disturbances without the knowledge of bounds. For unmatched uncertainties, optimal control theory is added to the controller design processes. Simulations on a pantograph are shown to verify the efficiency of the proposed fault-tolerant design approach