A computational model for geomagnetically trapped particle shells and kinematic parameters Technical report, Oct. 1965 - Jun. 1966

Computer program to calculate geomagnetically trapped particle shell model, drift rate, and bounce path

Synthesis of Multi-Radial Line Antenna for HIPERLAN

This paper is a postprint of a paper submitted to and accepted for publication in journal Electronics Letters and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library"[Abstract] We present a new antenna concept - the multi-radial travelling wave line antenna - that achieves a broadband conical radiation pattern suitable for use in multiple C-band wireless computer networks

New Toroidal Beam Antennas for WLAN Communications

[Abstract] The design of a number of new antennas that radiate linearly polarized toroidal beams is described. The developed procedures are based on the use of a method of moments commercial software tool. Several numerical examples, working at WLAN communication frequencies, are derived and analyzed. Two experimental prototypes validate the numerical result

Perturbation of the Phases of Taylor Field Samples in the Synthesis of Linear and Circular Array Antennas

[Abstract] Antenna design specifications do not usually restrict the phase of the radiated field. Antenna synthesis techniques generally exploit this freedom only indirectly, but direct phase perturbation can be fruitful

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Abstract On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (\u3e2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased \u3e90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Key Points Substorm dynamics are important for highly relativistic electron energization Cold plasma preconditioning is significant for rapid relativistic energization Relativistic / highly relativistic electron energization can occur in \u3c 5 hrs

Gradual diffusion and punctuated phase space density enhancements of highly relativistic electrons: Van Allen Probes observations

Abstract The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth\u27s radiation belts. Observations (up to E ~10 MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L ~4.0 ± 0.5). This reveals graphically that both competing mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession. Key Points Clear observations to higher energy than ever before Precise detection of where and how acceleration takes place Provides new eyes on megaelectron Volt

Event-specific chorus wave and electron seed population models in DREAM3D using the Van Allen Probes

Abstract The DREAM3D diffusion model is applied to Van Allen Probes observations of the fast dropout and strong enhancement of MeV electrons during the October 2012 double-dip storm. We show that in order to explain the very different behavior in the two dips, diffusion in all three dimensions (energy, pitch angle, and Lo) coupled with data-driven, event-specific inputs, and boundary conditions is required. Specifically, we find that outward radial diffusion to the solar wind-driven magnetopause, an event-specific chorus wave model, and a dynamic lower-energy seed population are critical for modeling the dynamics. In contrast, models that include only a subset of processes, use statistical wave amplitudes, or rely on inward radial diffusion of a seed population, perform poorly. The results illustrate the utility of the high resolution, comprehensive set of Van Allen Probes\u27 measurements in studying the balance between source and loss in the radiation belt, a principal goal of the mission. Key Points DREAM3D uses event-specific driving conditions measured by Van Allen Probes Electron dropout is due to outward radial diffusion to compressed magnetopause Event-specific chorus and seed electrons are necessary for the enhancement

Testing a Spectral Model of Tonal Affinity with Microtonal Melodies and Inharmonic Spectra

Tonal affinity is the perceived goodness of fit of successive tones. It is important because a preference for certain intervals over others would likely influence preferences for, and prevalences of, “higher-order” musical structures such as scales and chord progressions. We hypothesize that two psychoacoustic (spectral) factors—harmonicity and spectral pitch similarity—have an impact on affinity. The harmonicity of a single tone is the extent to which its partials (frequency components) correspond to those of a harmonic complex tone (whose partials are a multiple of a single fundamental frequency). The spectral pitch similarity of two tones is the extent to which they have partials with corresponding, or close, frequencies. To ascertain the unique effect sizes of harmonicity and spectral pitch similarity, we constructed a computational model to numerically quantify them. The model was tested against data obtained from 44 participants who ranked the overall affinity of tones in melodies played in a variety of tunings (some microtonal) with a variety of spectra (some inharmonic). The data indicate the two factors have similar, but independent, effect sizes: in combination, they explain a sizeable portion of the variance in the data (the model-data squared correlation is r2 = .64). Neither harmonicity nor spectral pitch similarity require prior knowledge of musical structure, so they provide a potentially universal bottom-up explanation for tonal affinity. We show how the model—as optimized to these data—can explain scale structures commonly found in music, both historical and contemporary, and we discuss its implications for experimental microtonal and spectral music