1,720,962 research outputs found
A novel low cost sensor for measuring cylinder pressure and improving performance of an internal combustion engine
No full textA new sensor has been developed which will enable engine pressure data to be available at a cost suitable for the average production vehicle. Unlike many previous devices this sensor will be suitable for the harsh environmental conditions of production vehicles themselves and not just the test environment. The sensor is small, extremely rugged and has a sufficiently wide bandwidth to be easily able to detect engine problems such as pre-ignition, miss-fire and malfunctioning engine components. Furthermore, the patented sensor technology does not require expensive electronic interfaces, but can use simple low-cost off the shelf components. The sensor's performance and limitations are discussed, based on real data from a single cylinder petrol engine. An analysis of the sensor output signals, showing both time and frequency domain data under varying load conditions, is also included
Sensor validation and fusion using the Nadaraya-Watson statistical estimator
No full textThe paper describes a novel integrated sensor validation and fusion scheme based on the Nadaraya-Watson statistical estimator. The basis of the sensor validation scheme is that observations used to implement the estimator are obtained from valid sensor readings. Pattern matching techniques are used to relate a measurement vector that is not consistent with the training data to the closest a-priori observation. Defective sensor(s) can be identified and 'masked', and the estimator reconfigured to compute the estimate using data from the remaining sensors. Test results are provided for a range of typical fault conditions using an array of thick film pH sensors. The new algorithm is shown to reliably detect and compensate for bias errors, spike errors, hardover faults, drift faults and erratic operation, affecting up to three of the five sensors in the array. The fused result is more accurate than the single best sensor
A study of the effect of fabrication parameter variation on the environmental characteristics of thick film strain gauges fabricated on steel substrates
No full textResults from a programme of research aimed at establishing the mechanisms behind the effects of fabrication parameter variation on the performance of thick film strain gauges on steel substrates are presented. The research is aimed at describing the effect on the repeatability of the device characteristics due to different choices of materials, thicknesses of gauges, firing regimes and geometrical orientation of the gauges. In particular the effects of load and temperature on the offset and gain characteristics of a variety of different sensor constructions have been explored. The sensors described here are of a type where the applied strain is parallel to the measured resistance path but orthogonal to the substrate (z[33]). It has been found that these devices exhibit different characteristics to conventional thick film strain gauges that help explain the mechanisms affecting gain and offset changes caused by temperature fluctuations and mechanical deformation
An evaluation of materials and processes employed in the construction of novel thick film force sensors
No full textNovel thick film strain gauges have been constructed using a z-axis orientation on insulated stainless steel for a variety of force sensing applications. These devices exhibit high gauge factor and good thermal stability compared with conventional x-axis devices and offer other mechanical advantages due to their mode of operation. The work reported here investigates the characteristics of different types of stainless steel substrate and different types of insulating material used in the construction of the sensors. Both ferritic and austenitic steels have been investigated, together with different resistive and insulative compositions. The temperature coefficient of resistance of the devices has been shown to be a complex function of device thickness, surface area and the difference between the thermal coefficients of expansion of the various materials employed
An investigation of the effect of binder type, concentration and poling conditions upon the characteristics of screen printed piezoelectric materials
No full textA comparison of thick-film chemical sensor characteristics in laboratory and on-line industrial process applications
No full textThick-film (TF) fabricated chemical sensor arrays have been extensively evaluated both under laboratory conditions and in on-line applications in various industrial processes. A comparison of device performance between these two extremes of environment is presented with particular reference to the sensor lifetimes and their ability to withstand fouling and scaling in the industrial processes to which they are applied. The TF sensors evaluated included those for the measurement of pH, dissolved-oxygen concentration, temperature, conductivity and redox potential. The industrial process environments in which the sensors were studied included closed-loop water re-use systems in power stations, a paper mill and an application involving the pH monitoring of print ink
Characterisation of screen printable piezoelectric thick-films
No full textExperimental techniques for measuring piezoelectric coefficient d33 of screen printed thick-film lead zirconate totanate (PZT) pastes are described, together with a comparison of these values for different paste formulations. In particular, the effect of type and concentration of the binder has been observed. Concentrations of between 0 and 30% binder by weight have been analysed for two different binders, lead (II) oxide and lead borosilicate. The results show that sensors utilising the piezoelectric effect of pzt have a greater sensitivity if formulated with a lead(II) oxide binder
Screen printed thick film subterranean and subaqueous environmental chemical sensor arrays
No full textThick film environmental and chemical sensor arrays designed for deployment in both subterranean and submerged aqueous applications are reported. Various choices of materials for these different applications have been evaluated and the responses of the different sensor types are compared and discussed. Results indicate that the choice of binder materials is critical to producing sensors capable of medium term deployment (days) as the binders not only affect the tradeoff between hydration time and drift but also have a bearing on device sensitivity. Sensor calibration is shown to remain an issue with long term deployments (e.g. several weeks) but this can be ameliorated in the medium term with the use of novel device fabrication and packaging technique
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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