We report on detailed laboratory experiments designed to illustrate the frictional behavior of granular volcanic debris. The materials include pyroclastic flow debris from Soufrière Hills Volcano, Montserrat, and from Stromboli Volcano, Italy, and lahar deposits from Mount St. Helens. Experiments were conducted in a servo-controlled, double-direct shear apparatus under conditions of displacemen...

An adaptive control scheme for emergency braking of vehicles is designed based on a LuGre dynamic model for the tire/road friction. The wheel angular speed and longitudinal vehicle acceleration information are used to design an observerestimator for vehicle velocity, friction internal state and friction parameters. A Lyapunov-based stabilizing controller is designed to achieve near maximum brak...

The linear viscoelastic behaviors of single semiflexible chains with internal friction are studied based on the wormlike-chain model. It is shown that the frequency dependence of the complex compliance in the high frequency limit is the same as that of the Voigt model. This asymptotic behavior appears also for the Rouse model with internal friction. We derive the characteristic times for both t...

Amber is a fossilized resin with a molecular structure similar to that of o t h e r s s i l hydrocarbons. It displays internal friction peaks similar to those of synthetic polymers and other macromolecular hydrocarbon materials. It is an excellent dielectric, and has a dielectric loss spectrum as well. We have utilized internal friction and dielectric loss spectra to elucidate some features of ...

In order to investigate lattice defects of 18-8 stainless steel after solution, precipitation and resolution treatments, thin films prepared from bulk specimens after the heat treatments were examined by means of transmission electron microscopy. In addition, measurements of the internal friction, specific gravity and electrical resistivity as well as Huey corrosion tests were conducted. The ex...

Internal friction (I.F.) and modulus measurements have been carried out as a function of temperature in order to study the Li mobility in an A1 8.1 at% Li 0.03 at% Zr alloy. The results show that the sequence of 6' and 6 precipitation can be followed through the evolution of the internal friction spectra. Two peaks appear in the internal friction spectrum. The low temperature peak Pz (450 K), h...