- An infrared (IR) thermometer seems to be the easiest way to an answer. Unfortunately the filament temperature can easily exceed the ranges of existing IR thermometers. This is an experiment that can be conducted in order to determine the temperature of a light bulb filmament.
- Here is an example of a mechanical system that has non-minimum phase. I used this example in June 2000 when teaching System Dyamics.
Modeling and Experimental Verification of Vibration and Noise Caused by the Cavity Modes of a Rolling Tire Under Static Loading, Revised Version
- This is the latest version of the paper whose abstract is listed below. This version follows the “Decision: Revise (Major Revisions)” by an editor of Journal of Sound and Vibration. Although this version was rejected by the journal, it has a much cleaner derivation.
Modeling and Experimental Verification of Vibration and Noise Caused by the Cavity Modes of a Rolling Tire Under Static Loading
- Tire cavity noise refers to the vehicle noise due to the excitation of the acoustic mode of a tire air cavity. Although two lowest acoustic modes are found to be sufficient to characterize the cavity dynamics, the dynamical response of these two modes is complicated by two major factors. First, the tire cavity geometry is affected by the static load applied to the tire due to vehicle weight. Second, the excitation force from the tire-road contact changes position as the tire rotates. In this paper, we first develop dynamic equations for the lowest modes of a rotating tire under the static load. Based on the model, we obtain the forces transmitted to the wheel from the tire resulting from the random contact force between the tire and the road surface. The transmitted forces along the fore/aft direction and the vertical direction show two peaks at frequencies that are dependent both on the tire static load and on the vehicle speed. We also analyze the dynamic spectra of the vavity air pressure. Our results show the presence of dominant peaks in the noise spectra. We further report experimental data on spindle responses and the model prediction. Our work thus provides a basic understanding for the interaction of tire cavity excitation and a tire/wheel assembly which is critical to develop strategies of mitigating the tire cavity noise in the early state of tire/wheel design.
- We present an extension of the Stoney equation. This extension is based on the calculation of stresses and deformation in a multiple layered plate with mismatching coefficients of thermal expansion. The analysis is first carried out for a multiple layered beam. The results are generalized to plates with isotropic in-plane stresses. We obtain the relationship between the stress in the film and the plate radius of curvature without requireing the film to be thinner than the substrate. Although the derivation is traightforward, the resulting equation has not been seen in the literature and it is of practical importance. Moreover, the resulting equation is exact.
- Intracytoplasmic sperm injection (ICSI), microinjection of a single spermatozoon into an oocyte, is a routine procedure in assisted repreduction programs. In many early experiments mercury is placed within the injection system because its high surface tension in the system facilitates the injection procedure. Unfortunately, mercury is cytotoxic and therefore alternative fluids or approaches are needed. Here we examine the main properties of mercury and their impact on the various aspects of ICSI. We conclude that the small momentum diffusivity of mercury is the most important contributing factor that facilitates the ICSI procedures. Not reported here are the unsuccessful attempts of developing mercury-less piezo-drills based on the findings of this paper. Further improvements in electronics should make it possible to develop such drills.