Storm hazards '79: F-106B operations summary

Preliminary flight tests with a F-106B aircraft were made on the periphery of isolated thunder cells using weather radar support. In addition to storm hazards correlation research, a direct-strike lightning measurement experiment and an atmospheric chemistry experiment were conducted. Two flights were made to close proximity to lightning generating cumulonimbus clouds; however, no direct lightning strikes were experienced. Although no discernible lightning transients were recorded, many operational techniques were identified and established

Universally Coupled Massive Gravity

We derive Einstein's equations from a linear theory in flat space-time using free-field gauge invariance and universal coupling. The gravitational potential can be either covariant or contravariant and of almost any density weight. We adapt these results to yield universally coupled massive variants of Einstein's equations, yielding two one-parameter families of distinct theories with spin 2 and spin 0. The Freund-Maheshwari-Schonberg theory is therefore not the unique universally coupled massive generalization of Einstein's theory, although it is privileged in some respects. The theories we derive are a subset of those found by Ogievetsky and Polubarinov by other means. The question of positive energy, which continues to be discussed, might be addressed numerically in spherical symmetry. We briefly comment on the issue of causality with two observable metrics and the need for gauge freedom and address some criticisms by Padmanabhan of field derivations of Einstein-like equations along the way.Comment: Introduction notes resemblance between Einstein's discovery process and later field/spin 2 project; matches journal versio

Instrumentation and control system for an F-15 stall/spin

An instrumentation and control system is described that was used for radio-controlled F-15 airplane model stall/spin research at the NASA-Langley Research Center. This stall/spin research technique, using scale model aircraft, provides information on the post-stall and spin-entry characteristics of full-scale aircraft. The instrumentation described provides measurements of flight parameters such as angle of attack and sideslip, airspeed, control-surface position, and three-axis rotation rates; these data are recorded on an onboard magnetic tape recorder. The proportional radio control system, which utilizes analog potentiometric signals generated from ground-based pilot inputs, and the ground-based system used in the flight operation are also described

Building a Web-Features Taxonomy for Structuring Web Design Guidelines

This paper proposes a framework for structuring web design guidelines that incorporates the hierarchies of web features and their semantic relationships with HTML and CSS. It is argued that this approach will be synchronous with the mental model of web designers, thus making the guidelines more usable. In addition, this approach embraces both external and internal aspects of web design, so there is little compromise on the coverage of web design issues. An experiment was conducted to compare the relative effectiveness of the proposed framework with other guideline structures (e.g., principle-oriented and a mixture of principle and feature-oriented). There was evidence that the principle-oriented guidelines performed worse than the other structures, but the analyses failed to establish that the proposed framework as the most effective. The experiment showed promising results but it suffered from small sample size. In spite of this, it is believed that the proposed taxonomy and framework has laid the groundwork for future research.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Association of the female of Perdita (Xeromacrotera) cephalotes (Cresson), and a replacement name for Perdita bohartorum Parker (Hymenoptera: Andrenidae)

The monotypic Perdita subgenus Xeromacrotera Timberlake is currently known only from the male sex. Here, the female of Perdita (Xeromacrotera) cephalotes (Cresson, 1878) is associated, resulting in two new junior synonyms of P. (X.) cephalotes: Perdita (Procockerellia) excellens Timberlake, 1958, new synonym and Perdita (Cockerellia) autumnalis Timberlake, 1977, new synonym. The true number of maxillary palpi are reported, and updated subgeneric and species diagnoses are provided. In addition, Perdita boharti Portman & Griswold, new name, is designated as a replacement name for the primary junior homonym P. bohartorum Parker, 1983 (not P. bohartorum Timberlake, 1956) and is assigned to the related subgenus Cockerellia Ashmead

Fixed-point elimination in the intuitionistic propositional calculus

It is a consequence of existing literature that least and greatest fixed-points of monotone polynomials on Heyting algebras-that is, the algebraic models of the Intuitionistic Propositional Calculus-always exist, even when these algebras are not complete as lattices. The reason is that these extremal fixed-points are definable by formulas of the IPC. Consequently, the $\mu$-calculus based on intuitionistic logic is trivial, every $\mu$-formula being equivalent to a fixed-point free formula. We give in this paper an axiomatization of least and greatest fixed-points of formulas, and an algorithm to compute a fixed-point free formula equivalent to a given $\mu$-formula. The axiomatization of the greatest fixed-point is simple. The axiomatization of the least fixed-point is more complex, in particular every monotone formula converges to its least fixed-point by Kleene's iteration in a finite number of steps, but there is no uniform upper bound on the number of iterations. We extract, out of the algorithm, upper bounds for such n, depending on the size of the formula. For some formulas, we show that these upper bounds are polynomial and optimal

Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT)

Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions