Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Finite element method. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

Two-phase modeling of deflagration-to-detonation transition in granular materials: Reduced equations

Abstract: Of the two-phase mixture models used to study deflagration-to-detonation transition in granular explosives, the Baer–Nunziato model is the most highly developed. It allows for unequal phase velocities and phase pressures, and includes source terms for drag and compaction that strive to erase velocity and pressure disequilibria. Since typical time scales associated with the equilibrating processes are small, source terms are stiff. This stiffness motivates the present work where we derive two reduced models in sequence, one with a single velocity and the other with both a single velocity and a single pressure. These reductions constitute outer solutions in the sense of matched asymptotic expansions, with the corresponding inner layers being just the partly dispersed shocks of the full model. The reduced models are hyperbolic and are mechanically as well as thermodynamically consistent with the parent model. However, they cannot be expressed in conservation form and hence require a regularization in order to fully specify the jump conditions across shock waves. Analysis of the inner layers of the full model provides one such regularization [Kapila et al., Phys. Fluids 9, 3885 (1997)], although other choices are also possible. Dissipation associated with degrees of freedom that have been eliminated is restricted to the thin layers and is accounted for by the jump conditions.

Role of thermal boundary resistance on the heat flow in carbon-nanotube composites

Abstract: We use classical molecular dynamics simulations to study the interfacial resistance for heat flow between a carbon nanotube and octane liquid. We find a large value of the interfacial resistance associated with weak coupling between the rigid tube structure and the soft organic liquid. Our simulation demonstrates the key role played by the soft vibration modes in the mechanism of the heat flow. These results imply that the thermal conductivity of carbon-nanotube polymer composites and organic suspensions will be limited by the interface thermal resistance and are consistent with recent experiments.

Methods and systems for controlling the operation of a tool

Abstract: Methods and systems for controlling the operation of a tool are provided These methods and systems may be used to control the operation of any tool, for example, a drill or a saw The methods and systems employ at least one sensor to detect at least one operational parameter of the tool, for example, drill speed or acceleration Instrumentation is used to process the data representing the parameter to determine characteristic values of the parameter, for example, amplitudes and frequencies These characteristic values are used to control the operation of the tool, to determine one or more properties of the material being acted on by the tool, or to monitor the condition of the tool Though aspects of the invention may be applied to a broad range of tools and machining processes, in one aspect, the methods and systems are used to monitor and control the operation of a surgical drilling process, for example, for the drilling of bone

Shewanella oneidensis MR-1 nanowires are outer membrane and periplasmic extensions of the extracellular electron transport components

Abstract: Bacterial nanowires offer an extracellular electron transport (EET) pathway for linking the respiratory chain of bacteria to external surfaces, including oxidized metals in the environment and engineered electrodes in renewable energy devices. Despite the global, environmental, and technological consequences of this biotic-abiotic interaction, the composition, physiological relevance, and electron transport mechanisms of bacterial nanowires remain unclear. We report, to our knowledge, the first in vivo observations of the formation and respiratory impact of nanowires in the model metal-reducing microbe Shewanella oneidensis MR-1. Live fluorescence measurements, immunolabeling, and quantitative gene expression analysis point to S. oneidensis MR-1 nanowires as extensions of the outer membrane and periplasm that include the multiheme cytochromes responsible for EET, rather than pilin-based structures as previously thought. These membrane extensions are associated with outer membrane vesicles, structures ubiquitous in Gram-negative bacteria, and are consistent with bacterial nanowires that mediate long-range EET by the previously proposed multistep redox hopping mechanism. Redox-functionalized membrane and vesicular extensions may represent a general microbial strategy for electron transport and energy distribution.