Naval Surface Warfare Center

About: Naval Surface Warfare Center is a facility organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Sonar & Radar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

A proposed hardness assurance test methodology for bipolar linear circuits and devices in a space ionizing radiation environment

Abstract: A hardness assurance test approach has been developed for bipolar linear circuits and devices in space. It consists of an initial test for dose rate sensitivity and a characterization test method to develop the conditions for a lot acceptance test at high dose rate. For parts with adequate design margin and/or well behaved parts a generic elevated temperature irradiation test is proposed.

Moving-Mass Roll Control System for Fixed-Trim Re-Entry Vehicle

Abstract: The ability of a moving-mass roll control system to control the roll attitude and trajectory of a simple fixed-trim re-entry vehicle using a linear roll autopilot is investigated. The governing equations of motion of the coupled vehicle-moving-mass two-body system, which form the basis of the study, are presented and discussed. An analysis of these equations reveals that dynamic and aerodynamic cross-coupling is produced by the operation of this control system; however, some vehicle design techniques are employed to mitigate these effects. The mass effectiveness parameter, obtained through linearization of the moment equation, is shown to be the key system design parameter. The design of an optimal linear roll autopilot using modern state-space methods is presented in detail, along with an optimal-gain-vector scheduling function. A nonlinear seven-degree-of-freedom simulation of a typical mission profile trajectory demonstrates the ability of the linear autopilot to effectively control the vehicle's roll attitude and trajectory. Dynamic, aerodynamic, and inertial cross-coupling do not appear to significantly degrade the control system's response.

Fully Distributed Coordination of Multiple DFIGs in a Microgrid for Load Sharing

Abstract: When wind power penetration is high, the available generation may be more than needed, especially for wind-powered microgrids working autonomously. Because the maximum peak power tracking algorithm may result in a supply-demand imbalance, an alternative algorithm is needed for load sharing. In this paper, a fully distributed control scheme is presented to coordinate the operations of multiple doubly-fed induction generators (DFIGs) in a microgrid. According to the proposed control strategy, each bus in a microgrid has an associated bus agent that may have two function modules. The global information discovery module discovers the total available wind generation and total demand. The load sharing control module calculates the generation reference of a DFIG. The consensus-based algorithm can guarantee convergence for microgrids of arbitrary topologies under various operating conditions. By controlling the utilization levels of DFIGs to a common value, the supply-demand balance can be maintained. In addition, the detrimental impact of inaccurate and outdated predictions of maximum wind power can be alleviated. The generated control references are tracked by coordinating converter controls and pitch angle control. Simulation results with a 5-DFIG microgrid demonstrate the effectiveness of the proposed control scheme.