Persistent Sunward Flow of ~1.6 MeV Protons at 1 Au

The anisotropy of 1.3 to 2.3 MeV protons has been measured with the Caltech Electron/Isotope Spectrometer aboard IMP-7 for periods between prompt solar particle events from 72/273 to 74/2. The diffusive anisotropy, which has been computed by subtracting the independently determined. convective anisotropy from the observed anisotropy, is predominantly directed toward the sun with a typical radial component of 14%

Neural networks in geophysical applications

Neural networks are increasingly popular in geophysics. Because they are universal approximators, these tools can approximate any continuous function with an arbitrary precision. Hence, they may yield important contributions to finding solutions to a variety of geophysical applications. However, knowledge of many methods and techniques recently developed to increase the performance and to facilitate the use of neural networks does not seem to be widespread in the geophysical community. Therefore, the power of these tools has not yet been explored to their full extent. In this paper, techniques are described for faster training, better overall performance, i.e., generalization,and the automatic estimation of network size and architecture

Electron Signatures of Satellite Sweeping in the Magnetosphere of Uranus

The Voyager 2 Cosmic Ray System found large-scale macrosignatures of satellite sweeping for MeV electrons near the orbits of the satellites Miranda, Ariel, and Umbriel in the magnetosphere of Uranus. Due to the large magnetic inclinations of satellite orbits at Uranus, sweeping rates vary along the orbits with the McIlwain L parameter. However, no evidence was found, where expected, for fresh sweeping signatures at such positions. Although the maximal electron intensity occurs near Voyager 2's minimum L (4.67) as predicted by the Q_3 field model, the intensity minima in the macrosignatures show large outward displacements (≤0.5 R_U) from minimum-L positions of the associated satellites. These radial displacements increased with measured electron energy and at higher magnetic latitudes. Pitch angle distributions are generally more anisotropic outside the macrosignatures and more isotropic within, as determined from comparison of inbound and outbound intensity profiles at different latitudes. These anisotropy measurements provide the basis for latitudinal flux extrapolation, which when coupled with power law scaling of spectral distributions allow the calculation of phase space density profiles. The latter show local minima in the macrosignatures and are indicative of distributed electron sources in the inner magnetosphere and/or nonadiabatic transport processes such as pitch angle scattering and magnetospheric recirculation. Preliminary diffusion coefficients with values D_(LL) ∼ 10^(−7)–10^(−6) RS² and radial dependence D_(LL) ∼ L^3–L^4 have been estimated for the macrosignatures. The low-order L dependence of D_(LL) is consistent with diffusion driven by ionospheric dynamo. However, quantitative modeling of radial and pitch angle diffusion is required to assess the formative processes for the macrosignatures before more physically meaningful transport parameters can be determined

Advanced composite aileron for L-1011 transport aircraft, task 1

Structural design and maintainability criteria were established and used as a guideline for evaluating a variety of configurations and materials for each of the major subcomponents. From this array of subcomponent designs, several aileron assemblies were formulated and analyzed. The selected design is a multirib configuration with sheet skin covers mechanically fastened to channel section ribs and spars. Qualitative analysis of currently available composite material systems led to the selection of three candidate materials on which comparative structural tests were conducted to measure the effects of environment and impact damage on mechanical property retention. In addition, each system was evaluated for producibility characteristics. From these tests, Thornel 300/5208 unidirectional tape was selected for the front spar and covers, and Thornel 300 fabric/5208 was chosen for the ribs

Zero-energy states in graphene quantum dots and rings

We present exact analytical zero-energy solutions for a class of smooth decaying potentials, showing that the full confinement of charge carriers in electrostatic potentials in graphene quantum dots and rings is indeed possible without recourse to magnetic fields. These exact solutions allow us to draw conclusions on the general requirements for the potential to support fully confined states, including a critical value of the potential strength and spatial extent.Comment: 8 pages, 3 figures, references added, typos corrected, discussion section expande

Transient intensity changes of cosmic rays beyond the heliospheric termination shock as observed at Voyager 1

This paper continues our studies of temporal variations of cosmic rays beyond the heliospheric termination shock (HTS) using Voyager 1 (V1) data when V1 was beyond 94 AU. This new study utilizes cosmic ray protons and electrons of several energies. Notable transient decreases of 5–50% are observed in galactic cosmic ray nuclei and electrons at V1 shortly after similar decreases are observed at Voyager 2 (V2) still inside the HTS. These decreases at V1 appear to be related to the large solar events in September 2005 and December 2006 and the resulting outward moving interplanetary shock. These two large interplanetary shocks were the largest observed at V2 after V1 crossed the HTS at the end of 2004. They were observed at V2 just inside the HTS at 2006.16 and 2007.43 providing timing markers for V1. From the timing of the intensity decreases observed at V1 as the shocks first reach the HTS and then later reach V1 itself, we can estimate the shock speed beyond the HTS to be between 240 and 300 km s^(−1) in both cases. From the timing of the decreases observed when the shock first reaches the HTS and then several months later encounters the heliopause, we can estimate the heliosheath thickness to be 31 ± 4 and 37 ± 6 AU, respectively, for the two sequences of three decreases seen at V1. These values, along with the distances to the HTS that are determined, give distances from the Sun to the heliopause of 121 ± 4 and 124 ± 6 AU, respectively