Explosive detonations at speeds faster than current theories predict have been shown to be possible in a powerful new computer simulation developed by a physical chemist and an aerospace engineer at Penn State. James B. Anderson, Evan Pugh Professor of Chemistry and Physics, and Lyle N. Long, Professor of Aerospace Engineering, say their simulation points the way toward the production of ultrafast detonations, which could lead to innovative propulsion systems for space travel and a better understanding of detonations in general, including those that occur at supersonic speeds in the tunnels of underground mines.
With the aid of an innovative chemical model supported by powerful computers, the researchers show that burning particles of highly reactive gas set on fire by an explosive shock wave can leap out in front of the wave and ride it like a surfer, sparking reactions in advance of the wave itself. "All the textbooks say that the velocity of a detonation in a reactive gas mixture can be no faster than the speed of sound in the hot burning gases, but our model shows this assumption may no longer be correct," says Anderson, whose paper is published in the current issue of the Journal of Chemical Physics (volume 118, issue 7, page 3102).
According to the previous prevailing theory, a detonation occurs when a shock wave from an explosion first blasts its way through a reactive gas, heating it until it ignites, then causing a chemical reaction that continues to power the explosive wave forward. The chemical reaction, which proceeds at a slower speed behind the initial shock wave, was thought to be limited to the speed of sound in the hot gases. "Previous models did not predict ultrafast, supersonic detonations, in which the explosion can move even faster than a shock wave in the hot gases," Anderson says.
Barbara K. Kennedy | EurekAlert!
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas
22.09.2017 | Forschungszentrum MATHEON ECMath
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy