814 research outputs found
Reynolds number effects on the transonic aerodynamics of a slender wing-body configuration
Aerodynamic forces and moments for a slender wing-body configuration are summarized from an investigation in the Langley National Transonic Facility (NTF). The results include both longitudinal and lateral-directional aerodynamic properties as well as slideslip derivatives. Results were selected to emphasize Reynolds number effects at a transonic speed although some lower speed results are also presented for context. The data indicate nominal Reynolds number effects on the longitudinal aerodynamic coefficients and more pronounced effects for the lateral-directional aerodynamic coefficients. The Reynolds number sensitivities for the lateral-directional coefficients were limited to high angles of attack
Cascading and Local-Field Effects in Non-Linear Optics Revisited; A Quantum-Field Picture Based on Exchange of Photons
The semi-classical theory of radiation-matter coupling misses local-field
effects that may alter the pulse time-ordering and cascading that leads to the
generation of new signals. These are then introduced macroscopically by solving
Maxwell's equations. This procedure is convenient and intuitive but ad hoc. We
show that both effects emerge naturally by including coupling to quantum modes
of the radiation field in the vacuum state to second order. This approach is
systematic and suggests a more general class of corrections that only arise in
a QED framework. In the semi-classical theory, which only includes classical
field modes, the susceptibility of a collection of non-interacting
molecules is additive and scales as . Second-order coupling to a vacuum mode
generates an effective retarded interaction that leads to cascading and local
field effects both of which scale as
In-Field Operations to Deliver Biomass to a Biorefinery
This study shows how “Satellite Storage Locations” (SSLs) can be sized and located to balance in-field hauling cost to the SSL and load-haul cost from the SSL to a biorefinery. The system uses in-field bale wagon to deliver bales of switchgrass to the SSL and year-round hauling from SSLs to a biorefinery with commercial equipment. An average labor productivity of 12 Mg/h was assumed for the in-field bale wagon. Based on average operating time to haul bales from a 16 ha field, the allowable in-field to SSL haul distance was 3.2 km. The mobilization cost to move equipment to the SSL for commercial load/haul operations is a factor in minimizing total cost, in-field hauling plus highway hauling. Analysis showed that mobilization cost is not as important as limiting in-field hauling cost. This result suggests that a large number of smaller SSLs may be the desired organization as compared to a fewer number of larger SSLs
Perspective: multi-dimensional coherent spectroscopy of perovskite nanocrystals
Recently, colloidal perovskite nanocrystals (PNCs) have emerged as an exciting material platform for optoelectronic applications due to their combination of facile synthesis routes, quantum size effects, and exceptional optical properties among other favorable characteristics. Given the focus on their optoelectronic properties, spectroscopic characterization of PNCs is crucial to rational design of their structure and device implementation. In this Perspective, we discuss how multi-dimensional coherent spectroscopy (MDCS) can resolve exciton dynamics and circumvent inhomogeneous broadening to reveal underlying homogeneous spectral lineshapes. We highlight recent applications of MDCS to PNCs in the literature, and suggest compelling problems concerning their microscopic physics to be addressed by MDCS in the future
Experimental evidence for soliton explosions
We show, experimentally and numerically, that Ti:sapphire mode-locked lasers can operate in a regime in which they intermittently produce exploding solitons. This happens when the laser operates near a critical point. Explosions happen spontaneously, but external perturbations can trigger them. In stable operation, all explosions have similar features, but are not identical. The characteristics of the explosions depend on the intracavity dispersion
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