16 research outputs found
An optical method for measuring exhaust gas pressure from an internal combustion engine at high speed
Measurement of exhaust gas pressure at high speed in an engine is important for engine efficiency,
CFD analysis, and turbocharger matching. Currently used piezoresistive sensors are bulky, require cooling, and
have limited lifetimes. A new sensor system uses an interferometric technique to measure pressure by
measuring the size of an optical cavity, which varies with pressure due to movement of a diaphragm. This
pressure measurement system has been used in gas turbine engines where the temperatures and pressures have
no significant transients but has never been applied to an internal combustion engine before, an environment
where both temperature and pressure can change rapidly. This sensor has been compared with a piezoresistive
sensor representing the current state-of-the-art at three engine operating points corresponding to both light load
and full load. The results show that the new sensor can match the measurements from the piezoresistive sensor
except when there are fast temperature swings, so the latter part of the pressure during exhaust blowdown is
only tracked with an offset. A modified sensor designed to compensate for these temperature effects is also
tested. The new sensor has shown significant potential as a compact, durable sensor, which does not require
external cooling
An optical method for measuring exhaust gas pressure from an internal combustion engine at high speed
Measurement of exhaust gas pressure at high speed in an engine is important for engine efficiency, CFD analysis, and turbocharger matching. Currently used piezoresistive sensors are bulky, require cooling, and have limited lifetimes. A new sensor system uses an interferometric technique to measure pressure by measuring the size of an optical cavity, which varies with pressure due to movement of a diaphragm. This pressure measurement system has been used in gas turbine engines where the temperatures and pressures have no significant transients but has never been applied to an internal combustion engine before, an environment where both temperature and pressure can change rapidly. This sensor has been compared with a piezoresistive sensor representing the current state-of-the-art at three engine operating points corresponding to both light load and full load. The results show that the new sensor can match the measurements from the piezoresistive sensor except when there are fast temperature swings, so the latter part of the pressure during exhaust blowdown is only tracked with an offset. A modified sensor designed to compensate for these temperature effects is also tested. The new sensor has shown significant potential as a compact, durable sensor, which does not require external cooling
Distributed temperature-change sensor-based on rayleigh backscattering in an optical-fiber
A frequency-modulated continuous-wave technique is used to detect the presence of frequency shifts in the Rayleigh-backscattered light in a single-mode optical fiber as a result of a changing temperature. The system is able to detect a rate of temperature change of 0.014 K/s, when a 20-cm length of fiber is heated. The system is also able to demonstrate a spatial resolution of better than 15 cm
Selective Excitation of CdSe/CdS Dot‐in‐Rod Nanocrystals and Distinct Roles of Electrons and Holes in Photophysical and Photochemical Interactions with Ambient Air
Effect of Capping Agent and Medium on Light-Induced Variation of the Luminescence Properties of CdTe Quantum Dots: A Study Based on Fluorescence Correlation Spectroscopy, Steady State and Time-Resolved Fluorescence Techniques
Flash synthesis of CdSe/CdS core-shell quantum Dots
We report on the "flash" synthesis of CdSe/CdS core-shell quantum dots (QDs). This new method, based on a seeded growth approach and using an excess of a carboxylic acid, leads to an isotropic and epitaxial growth of a CdS shell on a wurtzite CdSe core. The method is particularly fast and efficient, allowing the controllable growth of very thick CdS shells (up to 6.7 nm in the present study) in no more than 3 min, which is considerably shorter than in previously reported methods. The prepared materials present state-of-the-art properties with narrow emission and high photoluminescence quantum yields, even for thick CdS shells. Additionally, Raman analyses point to an alloyed interface between the core and the shell, which, in conjunction with the thickness of the CdS shell, results in the observed considerable reduction of the blinking rate. © 2013 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe