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: Radar & Sonar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

Advanced diagnostics to evaluate heterogeneity in lithium-ion battery modules

Abstract: Battery packs for electric and stationary applications experience varied operating conditions, including abuse—e.g., fast charging, overcharging, thermal, vibration, shock, etc.—throughout their lifetimes. Innovative diagnostic tools and algorithms that go beyond single cells and deal with modules and packs are essential for early detection of off-normal issues. High-resolution tools with known detection limits are key to developing appropriate mitigation strategies. With the advent of rapid impedance spectroscopy that can generate a broadband impedance spectrum in ∼10 s, the case for impedance-based diagnostics that can be readily aligned with other methods, such as incremental capacity or dQ.dV−1, has become promising. This study used the aforementioned diagnostic methods to identify realistic in-vehicle battery abnormalities (e.g., localized self-discharge and non-uniform aging), in series (up to 10S) and parallel (4P) strings, using 16 Ah graphite/NMC cells. The impedance-based diagnostic is found to be sensitive to the string size and state. Depending on the type of abnormality, detection frequency varied. The dQ.dV−1 method showed the potential to detect long-term aging-related heterogeneity in modules. In general, both the impedance and dQ.dV−1 methods were able to detect series strings’ abnormalities, but struggled to find those issues within parallel modules.

Magnetomechanical Coupling in Stress Annealed Fe-Ga and Fe-Al Alloys

Abstract: Magnetomechanical properties (coupling factor, piezomagnetic d-constant, and permeability) were obtained as a function of both magnetic field (0 to 600 Oe) and applied stress (-200 MPa to +50 MPa) for Fe100-x Gax (x=12.5, 18.4, and 22). To evaluate the coupling factors YB, the Young's modulus at constant induction, was measured and found to be 97, 75, and 67 GPa for x=12.5, 18.4, and 22, respectively. At low magnetic fields, relative permeabilities are greater than 800 for all alloys. Peak coupling factors exceeded 0.6 for the x=12.5 and x=18.4 alloys, whereas for the x=22 alloy, no measurable uniaxial energy was built into the alloy by stress annealing, and the d-constants and coupling factors were substantially lower. Model predictions of the inverse magnetostriction effect are presented for the x=18.4 alloy. Excellent fits obtained by the magnetization rotation model enable the calculation of all the magnetomechanical properties of the Fe-Ga system as well as the inverse magnetostrictive effect

Factors in an end user security expertise instrument

Abstract: Purpose The purpose of this study is to identify factors that determine computer and security expertise in end users. They can be significant determinants of human behaviour and interactions in the security and privacy context. Standardized, externally valid instruments for measuring end-user security expertise are non-existent. Design/methodology/approach A questionnaire encompassing skills and knowledge-based questions was developed to identify critical factors that constitute expertise in end users. Exploratory factor analysis was applied on the results from 898 participants from a wide range of populations. Cluster analysis was applied to characterize the relationship between computer and security expertise. Ordered logistic regression models were applied to measure efficacy of the proposed security and computing factors in predicting user comprehension of security concepts: phishing and certificates. Findings There are levels to peoples’ computer and security expertise that could be reasonably measured and operationalized. Four factors that constitute computer security-related skills and knowledge are, namely, basic computer skills, advanced computer skills, security knowledge and advanced security skills, and these are identified as determinants of computer expertise. Practical implications Findings from this work can be used to guide the design of security interfaces such that it caters to people with different expertise levels and does not force users to exercise more cognitive processes than required. Originality/value This work identified four factors that constitute security expertise in end users. Findings from this work were integrated to propose a framework called Security SRK for guiding further research on security expertise. This work posits that security expertise instrument for end user should measure three cognitive dimensions: security skills, rules and knowledge.

Biodegradation of asphalt cement-20 by aerobic bacteria.

Abstract: Seven gram-negative, aerobic bacteria were isolated from a mixed culture enriched for asphalt-degrading bacteria The predominant genera of these isolates were Pseudomonas, Acinetobacter, Alcaligenes, Flavimonas, and Flavobacterium The mixed culture preferentially degraded the saturate and naphthene aromatic fractions of asphalt cement-20 A residue remained on the surface which was resistant to biodegradation and protected the underlying asphalt from biodegradation The most potent asphalt-degrading bacterium, Acinetobacter calcoaceticus NAV2, excretes an emulsifier which is capable of emulsifying the saturate and naphthene aromatic fractions of asphalt cement-20 This emulsifier is not denatured by phenol