Search results for "Pressure sensor"
showing 10 items of 22 documents
Sensitivity and mode spectrum of a frequency-output silicon pressure sensor
1988
The vibrational mode spectrum of a silicon vibrating pressure sensor is investigated. Particular attention is given to the analysis of the vibration shapes, quality factors and relative sensitivity of the resonance frequencies as a function of pressure. It is shown that a pressure sensitivity of a few parts per million at one atmosphere can be achieved. Some comments are also made regarding an improved design of the device.
Application of an O-ring pinch device as a constant-pressure inlet (CPI) for airborne sampling
2020
We present a novel and compact design of a constant-pressure inlet (CPI) developed for use in airborne aerosol mass spectrometry. In particular, the inlet system is optimized for aerodynamic lenses commonly used in aerosol mass spectrometers, in which efficient focusing of aerosol particles into a vacuum chamber requires a precisely controlled lens pressure, typically of a few hectopascals. The CPI device can also be used in condensation particle counters (CPCs), cloud condensation nucleus counters (CCNCs), and gas-phase sampling instruments across a wide range of altitudes and inlet pressures. The constant pressure is achieved by changing the inner diameter of a properly scaled O-ring that…
DETERMINATION OF TDC IN INTERNAL COMBUSTION ENGINES BY A NEWLY DEVELOPED THERMODYNAMIC APPROACH
2010
Abstract In-cylinder pressure analysis is nowadays an indispensable tool in internal combustion engine research & development. It allows the measure of some important performance related parameters, such as indicated mean effective pressure (IMEP), mean friction pressure, indicated fuel consumption, heat release rate, mass fraction burned, etc. Moreover, future automotive engine will probably be equipped with in-cylinder pressure sensors for continuous combustion monitoring and control, in order to fulfil the more and more strict emission limits. For these reasons, in-cylinder pressure analysis must be carried out with maximum accuracy, in order to minimize the effects of its characteristic…
Measurement of brain tissue pressure in cold induced cerebral oedema.
1973
Experiments were performed in order to evaluate the concept that brain oedema is associated with an increase in local interstitial fluid pressure. Assuming that the pressure measured by the cotton wick technique represents the hydrostatic interstitial fluid pressure, the tissue pressure was recorded with pressure transducers in the white matter adjacent and remote to a local cold injury, in the opposite hemisphere, and in the cisterna magna. In 9 cats during steady-state conditions mean tissue pressures between 1.20±0.30 mm Hg and 2.33±0.80 mm Hg were found, as compared to a mean CSF pressure of 5.17±0.82 mm Hg. The tissue pressure was found to increase significantly adjacent to the lesion …
Artificial neural networks for predicting dorsal pressures on the foot surface while walking
2012
In this work, artificial neural networks (ANNs) are proposed to predict the dorsal pressure over the foot surface exerted by the shoe upper while walking. A model that is based on the multilayer perceptron (MLP) is used since it can provide a single equation to model the exerted pressure for all the materials used as shoe uppers. Five different models are produced, one model for each one of the four subjects under study and an overall model for the four subjects. The inputs to the neural model include the characteristics of the material and the positions during a whole step of 14 pressure sensors placed on the foot surface. The goal is to find models with good generalization capabilities, (…
Automated single ring infiltrometer with a low-cost microcontroller circuit
2015
Automation of a new single ring infiltrometer.Data acquisition system based on the open source microcontroller platform Arduino.New method to minimize the disturbance of the soil surface.New approach to process transducer output. A method to automate data collection with a compact infiltrometer under constant head conditions was developed. The infiltrometer consists of a containment ring with a small quasi-constant head of water (i.e., 2-3mm) that is controlled by a Mariotte reservoir and a data acquisition system based on the open source microcontroller platform Arduino and a differential pressure transducer. The presented design can be easily reproduced and operated.The infiltrometer was …
Gas protection optimization during Nd:YAG laser welding
2004
International audience; Many laser processes, such as welding or surface treatments are associated with an undesired phenomenon, which is oxidation. The solution commonly employed to solve this problem approaches the shielding gas and/or the shielding gas device. What we propose in this paper is a methodology with the goal to optimize the protection gas device design as well as the gas flow in the case of laser welding and surface treatments. The pressure created by the gas flow on the sample surface is recorded and analysed together with the operating parameters influence in order to reach the objectives. The nozzle system designed and presented below assures the protection against materia…
Sensing Capabilities Based on Dielectric Electro Active Polymers—Feasibility and Potential State-of-the-Art Application
2012
This paper presents the work in the area of sensing, using smart materials, more specific dielectric electro active polymers (DEAPs). Sensing is one of the main trio-characteristics of DEAPs; the trio-formations as applicable uses are actuator, transducer, and finally sensor. It is noted that one of the main value propositions whenever DEAP material is used, is the dual characteristics as the sensing/actuating capability. In the following work, the DEAP membrane will be modeled and the relation among the key variables (pressure and capacitance) will be determined. Hence, such a relation depends on the geometrical shape of the used membrane. The development process is carried out to propose …
The Experimental Validation of a New Thermodynamic Method for TDC Determination
2007
In-cylinder pressure analysis is becoming more and more important both for research and development purpose and for control and diagnosis of internal combustion engines; directly measured by means of a combustion chamber pressure transducers or evaluated by analysing instantaneous engine speed [1,2,3,4], incylinder pressure allows the evaluation of indicated mean effective pressure (IMEP), combustion heat release, combustion phase, friction pressure, etc...It is well known to internal combustion engine researchers that for a right evaluation of these quantities the exact determination of Top Dead Centre (TDC) is of vital importance: a 1° error on TDC determination can lead to evaluation err…
Optical activation of a silicon vibrating sensor
1986
The operation of a micromachined silicon vibrating sensor with both optical excitation and optical interrogation is reported. The proper locations at which the optical excitation should be applied for optimum excitation of different modes of resonance are described.