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Sensors, Volume 13, Issue 11 (November 2013), Pages 14248-15862

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Open AccessCorrection Correction: Grenez, F., et al. Wireless Prototype Based on Pressure and Bending Sensors for Measuring Gait Quality. Sensors 2013, 13, 9679–9703
Sensors 2013, 13(11), 15861-15862; https://doi.org/10.3390/s131115861
Received: 12 September 2013 / Revised: 29 September 2013 / Accepted: 29 September 2013 / Published: 21 November 2013
PDF Full-text (152 KB) | HTML Full-text | XML Full-text
Abstract
In [1], we would like to change “Gate” to “Gait” in the title, which should read “Prototype Based on Pressure and Bending Sensors for Measuring Gait Quality”. In Figure 7 we would like to change the analog inputs. The measurements should be between
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In [1], we would like to change “Gate” to “Gait” in the title, which should read “Prototype Based on Pressure and Bending Sensors for Measuring Gait Quality”. In Figure 7 we would like to change the analog inputs. The measurements should be between the sensor and the resistance, and not after the resistance. The revised figure is shown below. [...] Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Development and Evaluation of an Improved Technique for Pulmonary Function Testing Using Electrical Impedance Pneumography Intended for the Diagnosis of Chronic Obstructive Pulmonary Disease Patients
Sensors 2013, 13(11), 15846-15860; https://doi.org/10.3390/s131115846
Received: 8 September 2013 / Revised: 22 October 2013 / Accepted: 12 November 2013 / Published: 21 November 2013
Cited by 4 | PDF Full-text (972 KB) | HTML Full-text | XML Full-text
Abstract
Spirometry is regarded as the only effective method for detecting pulmonary function test (PFT) indices. In this study, a novel impedance pulmonary function measurement system (IPFS) is developed for directly assessing PFT indices. IPFS can obtain high resolution values and remove motion artifacts
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Spirometry is regarded as the only effective method for detecting pulmonary function test (PFT) indices. In this study, a novel impedance pulmonary function measurement system (IPFS) is developed for directly assessing PFT indices. IPFS can obtain high resolution values and remove motion artifacts through real-time base impedance feedback. Feedback enables the detection of PFT indices using only both hands for convenience. IPFS showed no differences in the sitting, supine, and standing postures during the measurements, indicating that patient posture has no effect on IPFS. Mean distance analysis showed good agreement between the volume and flow signal of IPFS (p < 0.05). PFT indices were detected in subjects to differentiate a chronic obstructive pulmonary disease (COPD) patient group from a normal group. The forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, and peak expiratory flow (PEF) in the COPD group were lower than those in the normal group by IPFS (p < 0.05). IPFS is therefore suitable for evaluating pulmonary function in normal and COPD patients. Moreover, IPFS could be useful for periodic monitoring of existing patients diagnosed with obstructive lung disease. Full article
(This article belongs to the Special Issue Biomedical Sensors and Systems)
Open AccessArticle Long-Wavelength Infrared Sensing by Cytochrome C Protein Thin Film Deposited by the Spin Coating Method
Sensors 2013, 13(11), 15833-15845; https://doi.org/10.3390/s131115833
Received: 7 October 2013 / Revised: 4 November 2013 / Accepted: 14 November 2013 / Published: 20 November 2013
Cited by 3 | PDF Full-text (2151 KB) | HTML Full-text | XML Full-text
Abstract
High infrared absorption, large temperature coefficient of resistance (TCR) and small 1/f noise are preferred characteristics for sensing materials used in bolometers. In this paper, we discuss a cytochrome c protein as a potential sensing material for long-wavelength bolometers. We simulated and experimentally
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High infrared absorption, large temperature coefficient of resistance (TCR) and small 1/f noise are preferred characteristics for sensing materials used in bolometers. In this paper, we discuss a cytochrome c protein as a potential sensing material for long-wavelength bolometers. We simulated and experimentally proved high infrared absorption of cytochrome c in the wavelength between 8 μm and 14 μm. Cytochrome c thin films were deposited on a hydrophilic surface using the spin coating method. The resistance variation with temperature is measured and we show that the TCR of cytochrome c thin films is consistently higher than 20%. The measured values of 1/f noise were as low as 2.33 × 1013 V2/Hz at 60 Hz. Finally, we test the reliability of cytochrome c by measuring the resistance changes over time under varying conditions. We found that cytochrome c thin films deteriorated significantly without appropriate packaging. Full article
(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)
Open AccessArticle Neuro-Inspired Spike-Based Motion: From Dynamic Vision Sensor to Robot Motor Open-Loop Control through Spike-VITE
Sensors 2013, 13(11), 15805-15832; https://doi.org/10.3390/s131115805
Received: 5 October 2013 / Revised: 11 November 2013 / Accepted: 13 November 2013 / Published: 20 November 2013
Cited by 20 | PDF Full-text (1220 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present a complete spike-based architecture: from a Dynamic Vision Sensor (retina) to a stereo head robotic platform. The aim of this research is to reproduce intended movements performed by humans taking into account as many features as possible from
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In this paper we present a complete spike-based architecture: from a Dynamic Vision Sensor (retina) to a stereo head robotic platform. The aim of this research is to reproduce intended movements performed by humans taking into account as many features as possible from the biological point of view. This paper fills the gap between current spike silicon sensors and robotic actuators by applying a spike processing strategy to the data flows in real time. The architecture is divided into layers: the retina, visual information processing, the trajectory generator layer which uses a neuroinspired algorithm (SVITE) that can be replicated into as many times as DoF the robot has; and finally the actuation layer to supply the spikes to the robot (using PFM). All the layers do their tasks in a spike-processing mode, and they communicate each other through the neuro-inspired AER protocol. The open-loop controller is implemented on FPGA using AER interfaces developed by RTC Lab. Experimental results reveal the viability of this spike-based controller. Two main advantages are: low hardware resources (2% of a Xilinx Spartan 6) and power requirements (3.4 W) to control a robot with a high number of DoF (up to 100 for a Xilinx Spartan 6). It also evidences the suitable use of AER as a communication protocol between processing and actuation. Full article
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Open AccessArticle Design and Implementation of a Micromechanical Silicon Resonant Accelerometer
Sensors 2013, 13(11), 15785-15804; https://doi.org/10.3390/s131115785
Received: 26 August 2013 / Revised: 4 November 2013 / Accepted: 7 November 2013 / Published: 19 November 2013
Cited by 11 | PDF Full-text (798 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The micromechanical silicon resonant accelerometer has attracted considerable attention in the research and development of high-precision MEMS accelerometers because of its output of quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability. Because of the mismatching thermal expansion
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The micromechanical silicon resonant accelerometer has attracted considerable attention in the research and development of high-precision MEMS accelerometers because of its output of quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability. Because of the mismatching thermal expansion coefficients of silicon and glass, the micromechanical silicon resonant accelerometer based on the Silicon on Glass (SOG) technique is deeply affected by the temperature during the fabrication, packaging and use processes. The thermal stress caused by temperature changes directly affects the frequency output of the accelerometer. Based on the working principle of the micromechanical resonant accelerometer, a special accelerometer structure that reduces the temperature influence on the accelerometer is designed. The accelerometer can greatly reduce the thermal stress caused by high temperatures in the process of fabrication and packaging. Currently, the closed-loop drive circuit is devised based on a phase-locked loop. The unloaded resonant frequencies of the prototype of the micromechanical silicon resonant accelerometer are approximately 31.4 kHz and 31.5 kHz. The scale factor is 66.24003 Hz/g. The scale factor stability is 14.886 ppm, the scale factor repeatability is 23 ppm, the bias stability is 23 μg, the bias repeatability is 170 μg, and the bias temperature coefficient is 0.0734 Hz/°C. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2013)
Open AccessArticle Two Novel Measurements for the Drive-Mode Resonant Frequency of a Micromachined Vibratory Gyroscope
Sensors 2013, 13(11), 15770-15784; https://doi.org/10.3390/s131115770
Received: 5 September 2013 / Revised: 1 November 2013 / Accepted: 1 November 2013 / Published: 19 November 2013
Cited by 1 | PDF Full-text (462 KB) | HTML Full-text | XML Full-text
Abstract
To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG), one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and
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To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG), one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA) and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle A Novel Porphyrin-Containing Polyimide Nanofibrous Membrane for Colorimetric and Fluorometric Detection of Pyridine Vapor
Sensors 2013, 13(11), 15758-15769; https://doi.org/10.3390/s131115758
Received: 16 October 2013 / Revised: 28 October 2013 / Accepted: 30 October 2013 / Published: 19 November 2013
Cited by 13 | PDF Full-text (495 KB) | HTML Full-text | XML Full-text
Abstract
A novel zinc porphyrin-containing polyimide (ZPCPI) nanofibrous membrane for rapid and reversible detection of trace amounts of pyridine vapor is described. The membrane displays a distinct color change, as well as dramatic variations in absorption and fluorescent emission spectra, upon exposure to pyridine
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A novel zinc porphyrin-containing polyimide (ZPCPI) nanofibrous membrane for rapid and reversible detection of trace amounts of pyridine vapor is described. The membrane displays a distinct color change, as well as dramatic variations in absorption and fluorescent emission spectra, upon exposure to pyridine vapor. This condition allows the detection of the analyte at concentrations as low as 0.041 ppm. The vapochromic and spectrophotometric responses of the membrane are attributed to the formation of the ZPCPI-pyridine complex upon axial coordination. From surface plasmon resonance analysis, the affinity constant of ZPCPI-pyridine complex was calculated to be (3.98 ± 0.25) × 104 L·mol−1. The ZPCPI nanofibrous membrane also showed excellent selectivity for pyridine vapor over other common amines, confirming its applicability in the manufacture of pyridine-sensitive gas sensors. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle On-Line Thickness Measurement for Two-Layer Systems on Polymer Electronic Devices
Sensors 2013, 13(11), 15747-15757; https://doi.org/10.3390/s131115747
Received: 25 September 2013 / Revised: 24 October 2013 / Accepted: 11 November 2013 / Published: 18 November 2013
Cited by 4 | PDF Full-text (699 KB) | HTML Full-text | XML Full-text
Abstract
During the manufacturing of printed electronic circuits, different layers of coatings are applied successively on a substrate. The correct thickness of such layers is essential for guaranteeing the electronic behavior of the final product and must therefore be controlled thoroughly. This paper presents
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During the manufacturing of printed electronic circuits, different layers of coatings are applied successively on a substrate. The correct thickness of such layers is essential for guaranteeing the electronic behavior of the final product and must therefore be controlled thoroughly. This paper presents a model for measuring two-layer systems through thin film reflectometry (TFR). The model considers irregular interfaces and distortions introduced by the setup and the vertical vibration movements caused by the production process. The results show that the introduction of these latter variables is indispensable to obtain correct thickness values. The proposed approach is applied to a typical configuration of polymer electronics on transparent and non-transparent substrates. We compare our results to those obtained using a profilometer. The high degree of agreement between both measurements validates the model and suggests that the proposed measurement method can be used in industrial applications requiring fast and non-contact inspection of two-layer systems. Moreover, this approach can be used for other kinds of materials with known optical parameters. Full article
(This article belongs to the Special Issue Optomechatronics)
Open AccessArticle A Doppler Transient Model Based on the Laplace Wavelet and Spectrum Correlation Assessment for Locomotive Bearing Fault Diagnosis
Sensors 2013, 13(11), 15726-15746; https://doi.org/10.3390/s131115726
Received: 27 September 2013 / Revised: 3 November 2013 / Accepted: 11 November 2013 / Published: 18 November 2013
Cited by 22 | PDF Full-text (712 KB) | HTML Full-text | XML Full-text
Abstract
The condition of locomotive bearings, which are essential components in trains, is crucial to train safety. The Doppler effect significantly distorts acoustic signals during high movement speeds, substantially increasing the difficulty of monitoring locomotive bearings online. In this study, a new Doppler transient
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The condition of locomotive bearings, which are essential components in trains, is crucial to train safety. The Doppler effect significantly distorts acoustic signals during high movement speeds, substantially increasing the difficulty of monitoring locomotive bearings online. In this study, a new Doppler transient model based on the acoustic theory and the Laplace wavelet is presented for the identification of fault-related impact intervals embedded in acoustic signals. An envelope spectrum correlation assessment is conducted between the transient model and the real fault signal in the frequency domain to optimize the model parameters. The proposed method can identify the parameters used for simulated transients (periods in simulated transients) from acoustic signals. Thus, localized bearing faults can be detected successfully based on identified parameters, particularly period intervals. The performance of the proposed method is tested on a simulated signal suffering from the Doppler effect. Besides, the proposed method is used to analyze real acoustic signals of locomotive bearings with inner race and outer race faults, respectively. The results confirm that the periods between the transients, which represent locomotive bearing fault characteristics, can be detected successfully. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle On the Convergence of Ionospheric Constrained Precise Point Positioning (IC-PPP) Based on Undifferential Uncombined Raw GNSS Observations
Sensors 2013, 13(11), 15708-15725; https://doi.org/10.3390/s131115708
Received: 11 September 2013 / Revised: 21 October 2013 / Accepted: 8 November 2013 / Published: 18 November 2013
Cited by 19 | PDF Full-text (1210 KB) | HTML Full-text | XML Full-text
Abstract
Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in
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Precise Point Positioning (PPP) has become a very hot topic in GNSS research and applications. However, it usually takes about several tens of minutes in order to obtain positions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time kinematic positioning services, therefore, a large effort has been made to tackle the convergence problem. One of the recent approaches is the ionospheric delay constrained precise point positioning (IC-PPP) that uses the spatial and temporal characteristics of ionospheric delays and also delays from an a priori model. In this paper, the impact of the quality of ionospheric models on the convergence of IC-PPP is evaluated using the IGS global ionospheric map (GIM) updated every two hours and a regional satellite-specific correction model. Furthermore, the effect of the receiver differential code bias (DCB) is investigated by comparing the convergence time for IC-PPP with and without estimation of the DCB parameter. From the result of processing a large amount of data, on the one hand, the quality of the a priori ionosphere delays plays a very important role in IC-PPP convergence. Generally, regional dense GNSS networks can provide more precise ionosphere delays than GIM and can consequently reduce the convergence time. On the other hand, ignoring the receiver DCB may considerably extend its convergence, and the larger the DCB, the longer the convergence time. Estimating receiver DCB in IC-PPP is a proper way to overcome this problem. Therefore, current IC-PPP should be enhanced by estimating receiver DCB and employing regional satellite-specific ionospheric correction models in order to speed up its convergence for more practical applications. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle A Stochastic Approach to Noise Modeling for Barometric Altimeters
Sensors 2013, 13(11), 15692-15707; https://doi.org/10.3390/s131115692
Received: 30 August 2013 / Revised: 22 October 2013 / Accepted: 13 November 2013 / Published: 18 November 2013
Cited by 11 | PDF Full-text (632 KB) | HTML Full-text | XML Full-text
Abstract
The question whether barometric altimeters can be applied to accurately track human motions is still debated, since their measurement performance are rather poor due to either coarse resolution or drifting behavior problems. As a step toward accurate short-time tracking of changes in height
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The question whether barometric altimeters can be applied to accurately track human motions is still debated, since their measurement performance are rather poor due to either coarse resolution or drifting behavior problems. As a step toward accurate short-time tracking of changes in height (up to few minutes), we develop a stochastic model that attempts to capture some statistical properties of the barometric altimeter noise. The barometric altimeter noise is decomposed in three components with different physical origin and properties: a deterministic time-varying mean, mainly correlated with global environment changes, and a first-order Gauss-Markov (GM) random process, mainly accounting for short-term, local environment changes, the effects of which are prominent, respectively, for long-time and short-time motion tracking; an uncorrelated random process, mainly due to wideband electronic noise, including quantization noise. Autoregressive-moving average (ARMA) system identification techniques are used to capture the correlation structure of the piecewise stationary GM component, and to estimate its standard deviation, together with the standard deviation of the uncorrelated component. M-point moving average filters used alone or in combination with whitening filters learnt from ARMA model parameters are further tested in few dynamic motion experiments and discussed for their capability of short-time tracking small-amplitude, low-frequency motions. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Active Tracking of Maja Squinado in the Mediterranean Sea with Wireless Acoustic Sensors: Method, Results and Prospectives
Sensors 2013, 13(11), 15682-15691; https://doi.org/10.3390/s131115682
Received: 9 September 2013 / Revised: 16 October 2013 / Accepted: 11 November 2013 / Published: 15 November 2013
PDF Full-text (172 KB) | HTML Full-text | XML Full-text
Abstract
The Sustainable TEchnologies for LittoraL Aquaculture and MArine REsearch (STELLA MARE) platform has as an objective to provide data for the management of the sea in relation with the fishing industry. In this paper, we introduce
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The Sustainable TEchnologies for LittoraL Aquaculture and MArine REsearch (STELLA MARE) platform has as an objective to provide data for the management of the sea in relation with the fishing industry. In this paper, we introduce the first experiment on the active tracking of a crab species, Maja squinado, symbolic of the deregulation of fishing activity. This paper introduces the method used for monitoring Maja squinado and the first collected data on the behavior of this little-known species. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Building Kinetic Models for Determining Vitamin C Content in Fresh Jujube and Predicting Its Shelf Life Based on Near-Infrared Spectroscopy
Sensors 2013, 13(11), 15673-15681; https://doi.org/10.3390/s131115673
Received: 4 September 2013 / Revised: 20 October 2013 / Accepted: 1 November 2013 / Published: 15 November 2013
Cited by 7 | PDF Full-text (307 KB) | HTML Full-text | XML Full-text
Abstract
Fresh jujube (Ziziphus jujube) is rich in vitamin C, which is an important quality index and generally decreases with storage time. The aim of this study was to build kinetic models for determining the vitamin C content, thus predicting the quality
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Fresh jujube (Ziziphus jujube) is rich in vitamin C, which is an important quality index and generally decreases with storage time. The aim of this study was to build kinetic models for determining the vitamin C content, thus predicting the quality characteristics and shelf life of fresh jujube. The quality changes of the jujube stored at room temperature (20 °C) were analyzed using near-infrared spectroscopy. The significant spectra were determined and a calibration model for vitamin C content was developed. The results showed that vitamin C content could be described by the zero-order kinetics model based on the regressions. In addition, the shelf life of the jujube at room temperature was calculated according to the regression model. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Unscented Particle Filtering for Estimation of Shipboard Deformation Based on Inertial Measurement Units
Sensors 2013, 13(11), 15656-15672; https://doi.org/10.3390/s131115656
Received: 9 September 2013 / Revised: 14 October 2013 / Accepted: 5 November 2013 / Published: 15 November 2013
Cited by 7 | PDF Full-text (546 KB) | HTML Full-text | XML Full-text
Abstract
Shipboard is not an absolute rigid body. Many factors could cause deformations which lead to large errors of mounted devices, especially for the navigation systems. Such errors should be estimated and compensated effectively, or they will severely reduce the navigation accuracy of the
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Shipboard is not an absolute rigid body. Many factors could cause deformations which lead to large errors of mounted devices, especially for the navigation systems. Such errors should be estimated and compensated effectively, or they will severely reduce the navigation accuracy of the ship. In order to estimate the deformation, an unscented particle filter method for estimation of shipboard deformation based on an inertial measurement unit is presented. In this method, a nonlinear shipboard deformation model is built. Simulations demonstrated the accuracy reduction due to deformation. Then an attitude plus angular rate match mode is proposed as a frame to estimate the shipboard deformation using inertial measurement units. In this frame, for the nonlinearity of the system model, an unscented particle filter method is proposed to estimate and compensate the deformation angles. Simulations show that the proposed method gives accurate and rapid deformation estimations, which can increase navigation accuracy after compensation of deformation. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Temperature Measurement in WTE Boilers Using Suction Pyrometers
Sensors 2013, 13(11), 15633-15655; https://doi.org/10.3390/s131115633
Received: 10 September 2013 / Revised: 28 October 2013 / Accepted: 11 November 2013 / Published: 15 November 2013
Cited by 10 | PDF Full-text (1075 KB) | HTML Full-text | XML Full-text
Abstract
The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum
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The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty. Full article
(This article belongs to the Special Issue Sensors for Harsh-Environment Applications)
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