General Dynamics

About: General Dynamics is a company organization based out in Fairfax, Virginia, United States. It is known for research contribution in the topics: Signal & Propellant. The organization has 5722 authors who have published 5819 publications receiving 85768 citations. The organization is also known as: GD & General Dynamics Corporation.

An empirical study of open-source and closed-source software products

Abstract: We describe an empirical study of open-source and closed-source software projects. The motivation for this research is to quantitatively investigate common perceptions about open-source projects, and to validate these perceptions through an empirical study. We investigate the hypothesis that open-source software grows more quickly, but does not find evidence to support this. The project growth is similar for all the projects in the analysis, indicating that other factors may limit growth. The hypothesis that creativity is more prevalent in open-source software is also examined, and evidence to support this hypothesis is found using the metric of functions added over time. The concept of open-source projects succeeding because of their simplicity is not supported by the analysis, nor is the hypothesis of open-source projects being more modular. However, the belief that defects are found and fixed more rapidly in open-source projects is supported by an analysis of the functions modified. We find support for two of the five common beliefs and conclude that, when implementing or switching to the open-source development model, practitioners should ensure that an appropriate metrics collection strategy is in place to verify the perceived benefits.

Electronic system for the stimulation of biological systems

Abstract: A receiver totally implanted within a living body is inductively coupled by two associated receiving coils to a physically unattached external transmitter which transmits two signals of different frequencies to the receiver via two associated transmitting coils. One of the signals from the transmitter provides the implanted receiver with precise control or stimulating signals which are demodulated and processed in a signal processor network in the receiver and then used by the body for stimulation of a nerve, for example, while the other signal provides the receiver with a continuous wave power signal which is rectified in the receiver to provide a source of electrical operating power for the receiver circuitry without need for an implanted battery.

Characterizing delamination growth in graphite-epoxy

Abstract: As part of an overall effort to develop durability and damage tolerance methodology for graphite-epoxy composites, coupon specimens have been developed to measure the fundamental static fracture and subcritical growth behavior of delaminations. Two basic designs, one for the tensile opening mode (Mode I) and one for the forward shear mode (Mode II), are described. These specimens were used to characterize the behavior of two types of interfaces (0/0 and 0/90) for static fracture, constant amplitude fatigue, and spectrum fatigue. Fracture mechanics technology was applied through the principles of strain-energy release rate. Three-dimensional finite-element analyses were employed to interpret the experimental results. A simple growth law was shown to correlate the constant-amplitude and spectrum-growth data. It was found that the applied cyclic load must be nearly equal to the critical static load to obtain observable growth in the tensile opening mode. On the other hand, the graphite-epoxy delamination growth rate in the forward shear mode is comparable to the aluminum growth rate in tension, which suggests that shear is the chief subcritical growth mode for graphite-epoxy.

Apparatus and method for problem solving using intelligent agents

Abstract: An apparatus and method for iterative problem solving that uses intelligent agents such as a brain agent, a profile agent, a personality agent, a knowledge agent and an error handling agent to interpret questions posed by a user and to provide responses back to the user. The apparatus and method may further use a mood agent, a visual agent, sound agent, a tactile agent, and a smell/taste agent and various connectors to external data sources to interpret questions and provide responses back to the user. The apparatus and method may further parse questions in a conceptual manner. The apparatus and method may further optimize its system performance by evolving with and reacting to user interactions.

Collisions of Electrons with Hydrogen Atoms. I. Ionization

Abstract: The cross section for ionization of the hydrogen atom on electron impact has been measured as a function of electron energy. A modulated beam of atoms and molecules in varying proportions, taken from a furnace, is crossed by a dc electron beam, and the positive ions formed are taken into a mass spectrometer. By using such modulation techniques, the ions formed by ionization of the beam are distinguished from the much larger number of ions formed by collisions of electrons with the residual gas in the vacuum chamber. From the study of the mass-spectrometer peak strengths as a function of temperature with constant gas flow, the ratio of the cross sections for ionization of the atom and the molecule is directly determined. The absolute atomic cross sections, determined by multiplying this ratio by the known molecular cross sections, are cross-checked by taking relative cross sections for the atom. Complete agreement with the first Born approximation is found only above about 250 ev. Deviations of experiment from theory at lower energies are as predicted qualitatively by theory.