KEYWORDS: Microsensors, Sensors, Resistors, Signal processing, Temperature metrology, Calibration, Bridges, Fluctuations and noise, Silicon, Tolerancing
A self-diagnosis method for hot film airflow mass microsensor has been developed for the vehicle air intake. Based on
the theory of heat transfer and airflow mass rate measurement for internal combustion engines, a hot film airflow mass
microsensor with self-diagnosis capability is designed. It is composed of a heat sensing unit, a temperature sensing unit
using a Heraeus silicon, a signal processor, a converters, a heater, a heating controller and a computer. The temperature
sensing unit is split into a heater upstream temperature sensing resistor and a heater downstream temperature sensing
resistor according to the air intake flow direction. From both theory and experiments, the relation between the heat
transfer rate of the heater and the airflow mass rate at the air intake are deduced under the working conditions of a certain
engine, and the temperature distribution rules in the heater surface, heater upstream and heater downstream are obtained.
These relations are regarded as a reference model for the self-diagnosis in the microsensor. Finally, the failure of the
microsensor can be detected by comparing the real-time measurement model with the reference model. Thus, this
method can not only measure mass airflow rates in real time, but also inspect diagnosis faults of the heat sensing unit and
the temperature sensing unit automatically.
The geometrical characteristics measurement of viscous objects is one of the development tendencies of dynamic geometrical characteristics measurement. This article deals with the technique of tomography image processing for geometrical characteristics measurement of viscous object. Based on the theory of photoelectric information processing, image segmentation, image preprocessing and object characteristic extraction from images are developed to increase the amount of information which can be obtained from viscous object images. The experimental results demonstrate that these methods cannot only distinguish the geometrical characteristics of viscous objects from tomography images in which the ratio of pixels between background and object image is about 9 to 1, but can also increase the image resolution by 30 percent. It is concluded that these methods can solve the problem to use computer tomography of dynamic geometrical characteristics measurement for non-destructive inspections.
The paper concentrates on the skills of tomography image processing and analysis for polymer configuration in polymer extrusion. Firstly, the tomography image segmentation is brought forward to resolve the problem that the amount of polymer information is small and the tomography image resolution is low, which comes from the great difference of physical dimension and material density between polymer (object) and processing equipment (background). And then, the object region extraction is performed to distinguish object region from segmentation image. Under the guidance of basic theory on polymer processing, the object configuration and its characteristics have been obtained by the tomography image measurement from the object region. The rheological property of polymer can be analyzed by the characteristics of object tomography configuration. Finally, the experiment result shows that this method can measure and analyze the polymer configuration and improve the measurement system resolution effectively. It has offered a novel experimental method to solve the problem that engineering material configuration in enclosed and complicated space is detested dynamically and nondestructively.
On the basis of the relation of polymer free volume and the stress and strain, a novel image measurement with computed digital tomography was developed for the polymer morphology during extrusion in the paper. The method synthetically utilizes the knowledge of nuclear physics, photo-electricity, polymer physics, computer technology and mathematics, the dynamic deformation and morphology of polymer can be visually obtained by the interaction of the atom of polymer or polymer chain and the photon beam to come from gamma ray, in which the photoemission, Compton effect and electron pair effect will be generated. The experimental result indicates the method can not only measure the dynamic deformation and morphology of extrusion polymer in the way of non-open, non-destroy and on-line, but also deduce the relationship between the mechanical properties and polymer morphology during extrusion.
A novel image measurement with computed digital tomography was developed for the conformation and structure of polymer material during extrusion in the paper. It is difficult to measure the configuration and structure of polymer material during extrusion. On the basis of the relation of polymer free volume and the temperature, pressure and viscosity during extrusion, the method synthetically utilizes the knowledge of nuclear physics, photo-electricity, mechanism, computer technology and mathematics, the dynamic configuration and flow behavior of polymer can be visually obtained by the interaction of the atom of polymer or polymer chain and the photon beam to come from gamma ray, in which the photoemission, Compton effect and electron pair effect will be generated. The experimental result indicates the method can not only measure the dynamic conformation and structure of extrusion polymer in the way of non-open, non-destroy and on-line, but also deduce the relationship between the mechanical properties and the conformation of extrusion polymer.
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