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.

Composite material for making cutting and abrading tools

Abstract: A superindurate, texturally stable abrasive composite material useful in the making of cutting and abrading tools, such as oil well drills, industrial metal cutting bits, mills, planar knives and abrasive grinders. The superficies of the object tool is comprised of the outer face of a tough matrix material and the projecting ends of a preferentially oriented indurate fibers or filaments, such as boron or the indurate intermetallic compounds of boron endowed with a hardness closely approaching that of industrial diamonds, which have been dispersed in collocated array and embodied within a tough matrix material such, for example, as in a sponge iron matrix which has been briquetted in the configuration of the object tool and then heated at temperatures sufficient for incipient fusion to occur to form the composite tool. Other ductile metals such as aluminum, nickel and cobalt, including certain of their alloys, together with steel and titanium are further examples of matrix materials which may be employed. The indurate filaments are so dispersed and collocated that the outer ends of the fibers or filaments are aligned normal to the tool''s work-taction surface and consequently to the surface of the object material to be cut or abraded.

On-Orbit Testing of the EO-1 Pulsed Plasma Thruster

Abstract: The Pulsed Plasma Thruster (PPT) Experiment on the Earth Observing 1 (EO-1) spacecraft has demonstrated the capability of a new generation PPT to perform spacecraft attitude control. The PPT is a small, self-contained pulsed electromagnetic propulsion system capable of delivering high specific impulse (900-1200 s) and very small impulse bits (10-1000 microN-s) at low average power (4 to 100 W). EO-1 has a single PPT that can produce torque in the positive or negative pitch direction and replace the function of the spacecraft s pitch reaction wheel. The flight validation experiment was designed to demonstrate the ability of the PPT to provide precision pointing accuracy, response and stability, and to confirm that the thruster plume and EMI effects on the spacecraft and instruments were benign. The PPT has been successfully used for pitch attitude control accumulating over 26 hours of operational time with over 96,000 pulses. Thruster performance has been nominal and all spacecraft subsystems and instruments continue to show no detrimental effects from PPT operation.

Linear and Nonlinear Optical Response in Silver Nanoclusters: Insight from a Computational Investigation

Abstract: We report a density functional theory (DFT) and time-dependent DFT (TDDFT) investigation of the thiolated silver nanoclusters [Ag44(SR)30]4–, Ag14(SR)12(PR′3)8, Ag31(SG)19, Ag32(SG)19, and Ag15(SG)11, which were synthesized and for which one-photon absorption (OPA) characterization is available. Our computational investigation based on careful examination of the exchange-correlation functional used in DFT geometry optimization and for the linear optical properties predictions by TDDFT, demonstrated good agreement with the measured linear absorption spectra, however dependent on the applied functional. Following the benchmarking, we evaluated the two-photon absorption (TPA) response using TDDFT, noting that accurate prediction of OPA is important for suppositions on the spectral range for TPA enhancement because of the sensitivity to the excitation energies. Although the TPA cross-section results are complicated by resonance effects and quantifying TPA cross sections for these systems is difficult, our res...