Potential Application of the Modulated Scatterer Technique to Multilayered Material Evaluation and Health Monitoring

Modulated scatterer technique (MST) is based on illuminating a small antenna, usually a dipole, loaded with a PIN diode, with an electromagnetic wave. The scattered (or reflected) wave from the probe may then be used to determine dielectric properties of the material in which the probe is located or embedded. The PIN diode is turned on and off which not only changes the impedance of the probe, but also modulates (with the same rate) the reflection from the probe. A major challenge associated with MST is detecting and distinguishing the desired probe response in the ever-present reflections from surrounding structures and materials. This challenge can be overcome by incorporating a swept-frequency method into the measurements. A swept-frequency technique allows the use of the Fourier Transform method which results in separate detection of the reflection from the probe (similar to pulsed methods). Having the ability to discriminate the probe response renders the MST technique useful for multilayer structure applications as well. The probe can be placed in a given layer of a material, and the properties of that layer can be monitored (regardless of the presence of other layers). Additionally, the probe can be placed at an interface and changes in that interface (such as disbonding) can be detected. The ratio of the reflection from a probe, between the on and off states, has been shown to be a unique technique for evaluating properties of materials. This paper presents the basis and some results of applying swept-frequency MST for inspecting layered materials

Work in Progress -- Instrumentation on a Truss Adapted for Pre-College Outreach

Engineering content is a valuable addition to pre-college instruction in science, technology, engineering, and mathematics (STEM) since it applies scientific concepts, illustrates scientific relevance and technology, and provides measurement opportunities. Also, complex systems and interactions can be shown. This work describes outreach resources using a seven-member instrumented truss apparatus. This aluminum bench-top model is scaled to support up to fifty pounds. Electrical resistance gauges are installed on several members for strain measurement. The resource set includes the truss apparatus, instrumentation, a PowerPoint presentation, and a background document. The pre-college objective is a set of demonstration resources for middle or high school classrooms. Effective outreach design is modeled by tailoring to accommodate curriculum standards, level-appropriate concept terms, and grade continuity. The resources were developed by students in an interdisciplinary college class on sensors and structures. The development activities involved testing the models and measurements and refining the construction. Selected resources were implemented and evaluated in a local middle school classroom. The interdisciplinary content includes structural, force analysis, sensing, and measurement components

Jet and underlying event properties as a function of charged-particle multiplicity in proton–proton collisions at √s = 7 TeV

Abstract Characteristics of multi-particle production in proton-proton collisions at √s = 7 TeV are studied as a function of the charged-particle multiplicity, N ch. The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity |η|0.25 GeV/c. Jets are reconstructed from charged-particles only and required to have pT>5 GeV/c. The distributions of jet pT, average pT of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of Nch and compared to the predictions of the pythia and herwig event generators. Predictions without multi-parton interactions fail completely to describe the Nch-dependence observed in the data. For increasing Nch, pythia systematically predicts higher jet rates and harder pT spectra than seen in the data, whereas herwig shows the opposite trends. At the highest multiplicity, the data–model agreement is worse for most observables, indicating the need for further tuning and/or new model ingredients