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.

Tris(triazolo)benzene and Its Derivatives: High-Density Energetic Materials**

Abstract: High-performance explosives: Tris(triazolo)benzene was synthesized and converted to its trinitro and trichloro derivatives (see scheme; R=NO(2), Cl). The heats of formation of this "high-nitrogen" compounds were calculated and combined with experimentally determined densities to determine detonation pressures and velocities. They exhibit high density, good thermal stability, high heats of formation, and moderate to good detonation properties.

Fast Response, Vertically Oriented Graphene Nanosheet Electric Double Layer Capacitors Synthesized from C2H2

Abstract: The growth and electrical characteristics of vertically oriented graphene nanosheets grown by radio frequency plasma-enhanced chemical vapor deposition from C2H2 feedstock on nickel substrates and used as electrodes in symmetric electric double layer capacitors (EDLC) are presented. The nanosheets exhibited 2.7 times faster growth rate and much greater specific capacitance for a given growth time than CH4 synthesized films. Raman spectra showed that the intensity ratio of the D band to G band versus temperature initially decreased to a minimum value of 0.45 at a growth temperature of 750 °C, but increased rapidly with further temperature increase (1.15 at 850 °C). The AC specific capacitance at 120 Hz of these EDLC devices increased in a linear fashion with growth temperature, up to 265 μF/cm2 (2 μm high film, 850 °C with 10 min growth). These devices exhibited ultrafast frequency response: the frequency response at −45° phase angle reached over 20 kHz. Consistent with the increase in D band to G band rat...

Satellite Geodesy—Foundations, Methods, and Applications

Abstract: This text is an updated English translation of Satellitengeodasie, a book that was published in German in 1989. The text is the first in many years that attempts to cover the broad spectrum of methods, applications, and systems, both classical and current, that have developed in the field of satellite geodesy. The material is presented in a structure that follows the major observational methods used in satellite geodesy: classical techniques, Doppler, GPS, laser, altimetry, and special methods including satellite-to-satellite tracking, satellite radiometry, and VLBI. Before introducing these observational techniques in detail, the author provides the fundamentals on reference frames, time signal propagation, orbital mechanics and basic applications of satellite geodesy in positioning, gravity field modeling, navigation, marine geodesy, kinematics, and geodynamics. An excellent reference list completes the text.

Experience from SIMMAN 2008—The First Workshop on Verification and Validation of Ship Maneuvering Simulation Methods

Abstract: The SIMMAN 2008 workshop was held in Copenhagen, Denmark in April 2008. The purpose of the workshop was to benchmark the prediction capabilities of different ship maneuvering simulation methods including systems- and CFD-based methods through systematic quantitative comparisons and validation against EFD data for tanker (KVLCC), container ship (KCS), and surface combatant (5415) hull form test cases. For the KVLCC test case, two stern shape variants named KVLCC1 and KVLCC2 giving different instability loops were included. Free model test data was compared with systems-based methods and CFD for specified free maneuvers. Some of the systems-based methods used provided PMM and CMT data, and two used CFD instead. CFD-based methods were used to simulate forced motions and were compared with PMM/CMT model test data. The submissions were blind in the sense that the benchmark model test data was not provided prior to the workshop, unless data was required as input to the simulation method. A total of 64 submissions were received for the free maneuver simulations, which included a wide range of the state-of-the-art methods in use today, such as PMM- and CMT-based methods, CFD-based methods, system identification, neural network tools and various empirical methods. For the forced motion simulations a total of 16 submissions were received, comprising different CFD-based methods such as RANS, URANS, and DES. This paper gives an overview of hulls, model tests, test cases, submissions, comparison results as well as the most important observations and conclusions.

Multiagent-Based Reinforcement Learning for Optimal Reactive Power Dispatch

Abstract: This paper proposes a fully distributed multiagent-based reinforcement learning method for optimal reactive power dispatch. According to the method, two agents communicate with each other only if their corresponding buses are electrically coupled. The global rewards that are required for learning are obtained with a consensus-based global information discovery algorithm, which has been demonstrated to be efficient and reliable. Based on the discovered global rewards, a distributed Q-learning algorithm is implemented to minimize the active power loss while satisfying operational constraints. The proposed method does not require accurate system model and can learn from scratch. Simulation studies with power systems of different sizes show that the method is very computationally efficient and able to provide near-optimal solutions. It can be observed that prior knowledge can significantly speed up the learning process and decrease the occurrences of undesirable disturbances. The proposed method has good potential for online implementation.