Transfer path based tyre absorption tests

The development process of a tyre usually involves a combination of simulation and testing techniques focused on characterizing acoustic/aerodynamic and vibrational phenomena. One of the acoustic phenomenon of interest is the absorption of the tyre, which affects the sound radiated. This properties is mainly related to local resonant effects, which can be changed by modifying the geometry of the tyre tread. A procedure is presented to determine the attenuation achieved due to a change in tyre tread configuration. The acoustic transfer path is measured from sound produced at one side of the tyre pavement contact area to the other. A miniature microphone and a small monopole with a known output have been developed to allow measurements inside the tyre grooves. Tyre sections with a circumferential groove only, as well as sections with additional side branches, have been evaluated

Operational modal analysis of a tyre using a PU probe based scanning technique

Tyre vibration can be studied with several experimental and simulation techniques. An important goal for a tyre manufacturer is to “tune” the resonant frequency of the tyre subsystem to reduce the structure-borne noise in the car interior. In this paper, a novel measurement technique is applied to determine the operational tyre deflection shapes under different conditions; i.e. free condition, loaded condition, and rolling condition. The vibrational behaviour of a tyre is studied using a PU probe, which comprises a sound pressure and a particle velocity sensor, and a scanning technique. The relative phase information is obtained using a static reference sensor. The experimental data can be used to validate simulated mode-shapes and resonant frequencies

Radical scavenging and anti-acetylcholinesterase activities of aqueous extract of wild pistachio (Pistacia atlantica Desf.) leaves

The purpose of this work is to assess the radical scavenging activity, acetylcholinesterase inhibition, and proline content of an aqueous extract from wild pistachio (Pistacia atlantica Desf.) leaves. The effect of aqueous extract on superoxide radical scavenging, hydroxyl radical scavenging, N,N-dimethyl-1,4-phenylendiammoniumdichloride (DMPD center dot+) radical scavenging, ABTS(center dot+) radical scavenging, nitric oxide scavenging, and beta-carotene bleaching activities was examined. This study found that the aqueous extract possesses considerable amounts of flavonoids (33.52 +/- 2.04 mu g catechin equivalents/mg of extract). The effect of this extract in scavenging activity of hydroxyl radical and DMPD center dot+ was significantly better than that of ascorbic acid and butylated hydroxyanisole (BHA). The effect of the extract in superoxide and ABTS(center dot+) was significantly similar than that of tested standard antioxidants. The proline content of the extract was found to be 0.54 +/- 0.01 mu g proline/mg of extract. Aqueous extract of P. atlantica inhibited acetylcholinesterase activity effectively with IC50 value of 58.05 +/- 0.12 mu g/mL