Acoustic spectrometer: Resonant sensing platform for measuring volumetric properties of liquid samples

A sensing platform for measuring volumetric properties of liquid samples using phononic crystals is presented in this paper. The proposed sensor concept is based on the transmission of elastic and acoustic waves through solids and liquids respectively to gather relevant information about the properties of the liquid under test. A major difference between this concept and the majority of current resonant sensors, like the well-known quartz crystal microbalance, is that the acoustic spectrometer proposed measures bulk properties and not interfacial properties of the liquid. The sensing platform uses a disposable analyte container to facilitate the measurement of hazardous substances and enable its use in biomedical applications. An electronic characterization system based on the acquisition of three mixed signals was developed to obtain the frequency response of the designed sensor. Finally, experimental and theoretical realizations were performed, using different analytes and showing characteristic transmission features that can be used as measures to determine the physical value speed of sound

Cavity Resonance Sensor with Disposable Analyte Container for Point of Care Testing

The use of phononic crystals and resonant structures as sensing platforms paves the way to the development of new biomedical technologies. An acoustic sensor with a resonant cavity and a disposable element was investigated in this paper. The sensor consists of seven layers with high acoustic impedance mismatch. The disposable element used was a glass spectrophotometry cuvette and, during the experimentation, it was filled with different liquid analytes showing characteristic transmission features that could be used as measures to differentiate and identify them. Experimental transmission curves were obtained using an electronic characterization system that uses a double sideband modulation technique to acquire valuable information about the structure being analyzed. Simulations using the 1-D transmission line method were performed to support the experimental realizations. The frequency of maximum transmission has been found to be strongly dependent on the speed of sound of the analyte under test

Liquefaction Resistance of Gravelly Soils

Liquefaction assessments of gravels and soils that contain a large gravel fraction are difficult. Undisturbed (intact) sampling of these soils is problematic and laboratory testing carried out on reconstituted samples or on frozen samples obtained from the field is time consuming, expensive, and interpretation of the results requires considerable judgment. Because of these and other issues, for a remote site in British Columbia, Canada (aka “Study Site”), it was decided to carry out the liquefaction potential assessment using existing published relationships and case history data on similar soils. This case history describes the approach utilized, including material mechanical properties, measured shear wave velocities and insitu density data obtained from shallow test pits excavated across the study site. Comparisons to published data on similar soils are discussed. To assess the liquefaction potential of the gravels, normalized shear wave velocity data were related to void ratio. The void ratio was then related to the CRR using published relationships on a similar gravelly soil tested in the laboratory. The liquefaction potential was assessed in the conventional manner comparing the cyclic resistance ratio (after appropriate consideration of correction factors used in laboratory cyclic testing) to the seismic demand (CSR). The approach described in the case history generalizes the methodology for application to other gravel deposits at other sites

Metacognition as Evidence for Evidentialism

Metacognition is the monitoring and controlling of cognitive processes. I examine the role of metacognition in ‘ordinary retrieval cases’, cases in which it is intuitive that via recollection the subject has a justified belief. Drawing on psychological research on metacognition, I argue that evidentialism has a unique, accurate prediction in each ordinary retrieval case: the subject has evidence for the proposition she justifiedly believes. But, I argue, process reliabilism has no unique, accurate predictions in these cases. I conclude that ordinary retrieval cases better support evidentialism than process reliabilism. This conclusion challenges several common assumptions. One is that non-evidentialism alone allows for a naturalized epistemology, i.e., an epistemology that is fully in accordance with scientific research and methodology. Another is that process reliabilism fares much better than evidentialism in the epistemology of memory

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El artículo es un comentario crítico a “Realismo, esencialismo y extensionalismo”, del profesor Ignacio Ávila. En particular, se contestan las críticas que el profesor Ávila hace a la metafísica esencialista, argumentando, principalmente, que esta metafísica es compatible con el fenómeno de la relatividad conceptual.This paper is a critical commentary to “Realism, Essentialism and Extensionalism”, by professor Ignacio Ávila. In particular, professor Ávila’s criticisms to an essentialist metaphysics are answered, arguing, mainly, that this metaphysics is compatible with the phenomenon of conceptual relativity

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