Very fine sand is prepared in a well-defined and fully decompactified state by letting gas bubble through it. After turning off the gas stream, a steel ball is dropped on the sand. On impact of the ball, sand is blown away in all directions ("splash") and an impact crater forms. When this cavity collapses, a granular jet emerges and is driven straight into the air. A second jet goes downwards i...

Water jet and Abrasive Water Jet (WJ/AWJ) are manufacturing technologies suitable for particular operations (cutting, milling, turning, surface treatment, etc.) on different types of materials. The use of water (or water mixed to abrasive in AWJ technology) allows working both soft and hard materials without damaging the interested area of the workpiece. In previous studies the authors have jus...

This paper presents a computational study on the aerodynamic effectiveness of vane-type fan-flow deflectors used for reducing jet noise from a supersonic turbofan exhaust with bypass ratio of 2.7. The numerical code solved the three-dimensional Reynolds-averaged Navier–Stokes equations. A series of nozzle configurations using deflector vanes of variable number, airfoil section, azimuthal mounti...

A shaped charge is an explosive device used to penetrate thick targets using a high velocity jet. A typical shaped charge contains explosive material behind a conical hollow. The hollow is lined with a compliant material, such as copper. Extremely high stresses caused by the detonation of the explosive have a focusing effect on the liner, turning it into a long, slender, stretching jet with a t...

The demand for ultrathin microprobes has been growing in diverse fields such as scanning probes in scanning tunneling microscopy ~STM!, atomic force microscopy ~AFM!, and micromachining. Mechanical fabrication methods generally involve precision mechanical operation such as turning, grinding, and wire electrodischarge grinding ~WEDG!. The convenience and variety of shaping in this approach is o...

The HH 34 superjet shows a steep velocity decrease (from ∼ 500 to ∼ 100 km s−1) over a distance of ∼ 2 pc on either side of the central source. We explore whether or not this behaviour could be interpreted as evidence for a slow “turning on” of the ejection velocity of the jet, and find that this is indeed possible, but only for an ejection velocity that has had a dramatic growth over the last ...

Electrochromic (EC) type e-paper is attracted with colorfulness and clearness. We have been researching and developing the material for EC type e-paper. We developed novel EC Polymers for e-paper. Our EC polymers are kinds of conductive polymers (CP). CP has some characteristics. One is electrochromism, and the other is electrochemical polymerization. Electrochromism of CP has a good memory eff...

At the beginning of their offshore migration, hatchling sea turtles enter the ocean at night and establish a course away from land by swimming directly into oceanic waves. How turtles can detect wave direction while swimming under water in darkness, however, has not been explained. Objects in a water column beneath the surface of the ocean describe a circular movement as waves pass above. In pr...

During the last 2 years, the knowledge on the metabolic pathway of tetrazepam, a muscle relaxant drug, was expanded by the fact that diazepam was identified as a degradation product of tetrazepam. The present study demonstrates that this metabolic conversion, recently discovered by in vivo studies, can also be predicted on the basis of a purely instrumental method, consisting of an electrochemi...