Sandia National Laboratories

About: Sandia National Laboratories is a facility organization based out in Livermore, California, United States. It is known for research contribution in the topics: Laser & Combustion. The organization has 21501 authors who have published 46724 publications receiving 1484388 citations. The organization is also known as: SNL & Sandia National Labs.

Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers

Abstract: Alkaline anion exchange membrane (AEM) electrolysers to produce hydrogen from water are still at an early stage of development, and their performance is far lower than that of systems based on proton exchange membranes. Here, we report an ammonium-enriched anion exchange ionomer that improves the performance of an AEM electrolyser to levels approaching that of state-of-the-art proton exchange membrane electrolysers. Using rotating-disk electrode experiments, we show that a high pH (>13) in the electrode binder is the critical factor for improving the activity of the hydrogen- and oxygen-evolution reactions in AEM electrolysers. Based on this observation, we prepared and tested several quaternized polystyrene electrode binders in an AEM electrolyser. Using the binder with the highest ionic concentration and a NiFe oxygen evolution catalyst, we demonstrated performance of 2.7 A cm−2 at 1.8 V without a corrosive circulating alkaline solution. The limited durability of the AEM electrolyser remains a challenge to be addressed in the future. Anion exchange membrane water electrolysers have potential cost advantages over proton exchange membrane electrolysers, but their performance has lagged behind. Here the authors investigate the cause of the poor performance of anion exchange membrane electrolysers and design ionomers that can overcome some of the challenges.

Passive data link layer 802.11 wireless device driver fingerprinting

Abstract: Motivated by the proliferation of wireless-enabled devices and the suspect nature of device driver code, we develop a passive fingerprinting technique that identifies the wireless device driver running on an IEEE 802.11 compliant device. This technique is valuable to an attacker wishing to conduct reconnaissance against a potential target so that he may launch a driver-specific exploit. In particular, we develop a unique fingerprinting technique that accurately and efficiently identifies the wireless driver without modification to or cooperation from a wireless device. We perform an evaluation of this fingerprinting technique that shows it both quickly and accurately fingerprints wireless device drivers in real world wireless network conditions. Finally, we discuss ways to prevent fingerprinting that will aid in improving the security of wireless communication for devices that employ 802.11 networking.

Shape memory and pseudoelasticity in metal nanowires.

Abstract: Structural reorientations in metallic fcc nanowires are controlled by a combination of size, thermal energy, and the type of defects formed during inelastic deformation. By utilizing atomistic simulations, we show that certain fcc nanowires can exhibit both shape memory and pseudoelastic behavior. We also show that the formation of defect-free twins, a process related to the material stacking fault energy, nanometer size scale, and surface stresses is the mechanism that controls the ability of fcc nanowires of different materials to show a reversible transition between two crystal orientations during loading and thus shape memory and pseudoelasticity.

A note on non-simple heat conduction

Abstract: In einem nicht-einfachen Material kann die Warmeubertragung durch zwei Temperaturen geregelt werden; die eine regelt die Strahlung, die andere die Leitung. In dieser Arbeit zeigen wir unter Benutzung fruherer Ergebnisse, dass bei stationaren Bedingungen die Differenz der beiden Temperaturen proportional zur Strahlungsdichte ist.