Modelling tyre noise in finite element simulations for pass-by noise predictions

Fulfilling the current pass-by noise regulation is a challenge for the original equipment manufacturers and their suppliers. And it's not going to improve over time. Any possible ways to reduce the exterior noise can happen to be beneficial. In this context, simulations are natural alternatives to costly and long measurement campaigns to quantify the benefits of acoustic treatments. Nevertheless, modelling procedures to tackle this type of issues are far from being well-established, even though the literature is rich with studies describing the complex processes involved in the tyre–road contact. Very often, when it comes to full-vehicle modelling, tyre sources are replaced by simple sources as monopoles, thus introducing a physical simplification. This paper is concerned with the tyre noise modelling in finite element simulation in the perspective to assess the pass-by noise of a car. For that, the sound radiated by validated velocity maps from a tyre–road noise simulation model at different speeds and for different loads is compared with the noise radiated by monopoles in the close vicinity of the tyres. The aim is to define the limitation related to the use of the monopoles in order to correctly capture the relevant physics in the simulation.

Study on Influence of Divided Conductor with Mechanical Properties on Operating over Voltage in Power System

This paper analyzed the influence that divided conductor to electrical fast transient burst. Divided conductor may change the magnetic field distribution around the conductor, but accordingly increased conductors electrical susceptance. The mechanism that the disconnecting switch cut off the power line when the no-load current is at peak and electric arc distinguished when the current pass zero and accordingly restraining measure is proposed. The outcome showed that the model can simulate the electrical fast transient burst in capacitive power line and makes it easy to analysis complex power system problems based on simple model. The method is proved to be correct and enforceable by validation of protective measures.

Various Contrasts Identifiable From the Backside of a Chip by 1.3μm Laser Beam Scanning and Current Change Imaging

We can identify various contrasts by scanning an 1.3 um laser beam from the backside of a chip and displaying current changes as brightness changes on a CRT, because the 1.3 um laser beam generates no OBIC signal and can penetrate P- Si substrate with little intensity degradation. The contrasts we have confirmed up to now are: (1) Current pass contrast at Al lines caused by OBIRCH, (2) Defect contrast at Al interconnects caused by OBIRCH, (3) Current pass contrast at a poly Si lines caused by OBIRCH, (4) Parasitic MIM (metal-insulator-metal) contrast caused by temperature dependence of MIM current, (5) Schottky-barrier contrast caused by internal photoemission.

On the kathode fall of potential in gases

It has been shown by Hittorf that when an electric current pass through a tube containing a gas at a pressure of a few millimeter there is a rapid fall of potential near each of the electrodes, with much more gentle fall in the space between, and whilst the fall near the anode and in the positive column varies with the density of gas and the current strength, the fall near the kathode is constant Warburg has made careful experiments on the kathode fall, and is fully established its constancy. If the gas is pure and dry, electrodes clean, and of a metal not acted on chemically by the gas the current not so strong as to make the negative glow cover the role kathode or extend to the walls of the tube, the kathode fall a definite value for each gas—a value that is independent of the pressure of the gas, or of the current strength, and that appears, in to be a constant of the gas.

Experiments on the influence of magnetism on polarized light

The object of this notice is to communicate some recent experi­ments on diamagnetism, and particularly on the influence of mag­netism on polarized light. The following extracts are in the words of the author :— The apparatus I employed in these experiments was an electro­magnetic apparatus invented by M.Rumkorf, and described by M.Biot at a meeting of the Academy of Sciences of Paris, and consisting of a powerful electro-magnet, of which the soft iron cylinder is traversed by a hole in the direction of the length of the axis, through which hole the ray of polarized light is made to pass; and the voltaic cur­rent which I employed on this occasion was that of seven pair of Grove’s construction. I made my first experiment with a piece of heavy glass, which I received from Faraday himself. In order to assure myself of the exact amount of rotation induced by magnetic action, I caused the ray of light, before it reached the heavy glass , to pass through the system invented by M. Soleil, consisting of two equal plates of perpendicular quartz, placed side by side; the one turning to the right, the other to the left. I ascertained, first of all, the rotation produced by making the current pass sometimes in one direction, and sometimes in the other ; the two rotations, one to the right, the other to the left, thus produced, were exactly the same. Then I compressed slightly the middle part of the piece of heavy glass, in the same manner as one compresses pieces of glass. I was then obliged to turn the eyepiece in a certain direction in order to restore the image to its first condition; in my experiments I always had to turn it, after compression, towards the right. I next made the current pass, first in one direction, then in the other. The ge­neral facts which I have observed constantly and without exception are the following :— The rotation produced by the magnet on the com­pressed piece of heavy glass is not the same to the right as it is to the left: the rotation produced by the magnet is considerably greater in the direction of the rotation produced by compression than it is in the contrary direction: the rotation produced by the magnet on the com­pressed heavy glass, and in the direction of the rotation produced by the compression, is greater than that produced by the same magnet on glass which has not been compressed, and the rotation in the contrary direc­tion is less. The following are the numerical results . “In one experiment I obtained on a piece of heavy glass not com­pressed, 3° of rotation to the right or to the left, according to the direction of the current: on slightly compressing the glass, I had to turn to the right the eyepiece to 4°, 5°, and even to 8° in order to restore the image to its first condition. In closing the circuit, the rotation produced in the same direction as that due to compression wras 3½° or 4°, while the rotation produced in the contrary direction was from 2° to 1½°. On ceasing to compress the glass, I obtained the same phenomena as I had observed before the compression.