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13 pages, 5362 KiB

Open AccessArticle

Experimental Investigation of High Temperature-Resistant Inductive Sensor for Blade Tip Clearance Measurement

by Ziyu Zhao, Zhenxia Liu, Yaguo Lyu and Yajun Gao

Sensors 2019, 19(1), 61; https://doi.org/10.3390/s19010061 - 24 Dec 2018

Cited by 17 | Viewed by 4113

Abstract

Turbine tip clearance of aero-engine is important to engine performance. Proper control of rotor tip clearance contributes to engine efficiency improvement and fuel consumption reduction. Therefore, accurate tip clearance measurement is essential. The inductive measurement method is one of the non-contact distance measurement [...] Read more.

Turbine tip clearance of aero-engine is important to engine performance. Proper control of rotor tip clearance contributes to engine efficiency improvement and fuel consumption reduction. Therefore, accurate tip clearance measurement is essential. The inductive measurement method is one of the non-contact distance measurement methods, which has the characteristics of high sensitivity, fast response speed and strong anti-interference ability. Based on the principle of inductive sensor measuring tip clearance, the ambient temperature change will cause the material electromagnetic performance change for the conductivity and permeability varies with temperature. The calibration experiment was conducted to obtain the sensor resolution and sensing range. The effect of temperature on sensor parameters was extracted from high temperature experiment data. Results show the resolution of planar coil made of platinum wire can be 10 μm and the maximum sensing range can reach 5 mm. At temperature from 500 ℃ to 1100 ℃, coil inductance almost does not change with temperature while coil resistance varies exponentially with temperature, that means the coil inductance variation can reflect the tip clearance change and resistance can indicate the measuring temperature. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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10 pages, 2681 KiB

Open AccessArticle

A Simple Graphene NH₃ Gas Sensor via Laser Direct Writing

by Dezhi Wu, Qianqian Peng, Shan Wu, Guangshun Wang, Lei Deng, Huiling Tai, Lingyun Wang, Yajie Yang, Linxi Dong, Yang Zhao, Jinbao Zhao, Daoheng Sun and Liwei Lin

Sensors 2018, 18(12), 4405; https://doi.org/10.3390/s18124405 - 13 Dec 2018

Cited by 52 | Viewed by 8557

Abstract

Ammonia gas sensors are very essential in many industries and everyday life. However, their complicated fabrication process, severe environmental fabrication requirements and desorption of residual ammonia molecules result in high cost and hinder their market acceptance. Here, laser direct writing is used to [...] Read more.

Ammonia gas sensors are very essential in many industries and everyday life. However, their complicated fabrication process, severe environmental fabrication requirements and desorption of residual ammonia molecules result in high cost and hinder their market acceptance. Here, laser direct writing is used to fabricate three parallel porous 3D graphene lines on a polyimide (PI) tape to simply construct an ammonia gas sensor. The middle one works as an ammonia sensing element and the other two on both sides work as heaters to improve the desorption performance of the sensing element to ammonia gas molecules. The graphene lines were characterized by scanning electron microscopy and Raman spectroscopy. The response and recovery time of the sensor without heating are 214 s and 222 s with a sensitivity of 0.087% ppm⁻¹ for sensing 75 ppm ammonia gas, respectively. The experimental results prove that under the optimized heating temperature of about 70 °C the heaters successfully help implement complete desorption of residual NH₃ showing a good sensitivity and cyclic stability. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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19 pages, 6545 KiB

Open AccessArticle

A Novel Acoustic Filtering Sensor for Real-Time Tension Monitoring of Hoist Wire Ropes

by Xiaoguang Zhang, Zhenyue Song, Jianpu Da and Jianbao Fu

Sensors 2018, 18(9), 2864; https://doi.org/10.3390/s18092864 - 30 Aug 2018

Cited by 5 | Viewed by 3872

Abstract

The real-time tension monitoring of wire ropes is a universal way to judge whether the hoist is overloaded in the special working environment of the coal mine. However, due to the strong drafts, unevenness of guide and flexible vibration of wire ropes, it [...] Read more.

The real-time tension monitoring of wire ropes is a universal way to judge whether the hoist is overloaded in the special working environment of the coal mine. However, due to the strong drafts, unevenness of guide and flexible vibration of wire ropes, it is a challenge to monitor the tension with high accuracy. For this purpose, a new type of acoustic filtering sensor is designed in this study. To adapt to the violent vibration during the monitoring process, a structure with a cylindrical cavity and a narrow gap is designed in the sensor. The coupling between the internal fluid and sensor structure can greatly absorb the vibration energy. With the view of optimizing the filtering performance of the sensor, the influences on the filtering characteristics are presented and analyzed through employing different structural and acoustic parameters in simulations. Finally, acoustic filtering sensor prototypes based on optimized parameters are calibrated and tested in a real coal mine. The results have revealed that our acoustic filtering sensor can not only address the deficiencies of current pressure sensors in coal mining and achieve tension monitoring in real-time, but is also able to diagnose and forecast the occurrence of tension imbalance accidents. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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9 pages, 3198 KiB

Open AccessArticle

Adhesive-Free Bonding of Monolithic Sapphire for Pressure Sensing in Extreme Environments

by Jihaeng Yi

Sensors 2018, 18(8), 2712; https://doi.org/10.3390/s18082712 - 17 Aug 2018

Cited by 13 | Viewed by 4456

Abstract

This paper presents a monolithic sapphire pressure sensor that is constructed from two commercially available sapphire wafers through a combination of reactive-ion etching and wafer bonding. A Fabry–Perot (FP) cavity is sealed fully between the adhesive-free bonded sapphire wafers and thus acts as [...] Read more.

This paper presents a monolithic sapphire pressure sensor that is constructed from two commercially available sapphire wafers through a combination of reactive-ion etching and wafer bonding. A Fabry–Perot (FP) cavity is sealed fully between the adhesive-free bonded sapphire wafers and thus acts as a pressure transducer. A combination of standard silica fiber, bonded sapphire wafers and free-space optics is proposed to couple the optical signal to the FP cavity of the sensor. The pressure in the FP cavity is measured by applying both white-light interferometry and diaphragm deflection theory over a range of 0.03 to 3.45 MPa at room temperature. With an all-sapphire configuration, the adhesive-free bonded sapphire sensor is expected to be suitable for in-situ pressure measurements in extreme harsh environments. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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14 pages, 2782 KiB

Open AccessArticle

High Temperature High Sensitivity Multipoint Sensing System Based on Three Cascade Mach–Zehnder Interferometers

by Na Zhao, Qijing Lin, Zhuangde Jiang, Kun Yao, Bian Tian, Xudong Fang, Peng Shi and Zhongkai Zhang

Sensors 2018, 18(8), 2688; https://doi.org/10.3390/s18082688 - 16 Aug 2018

Cited by 20 | Viewed by 3842

Abstract

A temperature multipoint sensing system based on three cascade Mach–Zehnder interferometers (MZIs) is introduced. The MZIs with different lengths are fabricated based on waist-enlarged fiber bitapers. The fast Fourier transformation is applied to the overlapping transmission spectrum and the corresponding interference spectra can [...] Read more.

A temperature multipoint sensing system based on three cascade Mach–Zehnder interferometers (MZIs) is introduced. The MZIs with different lengths are fabricated based on waist-enlarged fiber bitapers. The fast Fourier transformation is applied to the overlapping transmission spectrum and the corresponding interference spectra can be obtained via the cascaded frequency spectrum based on the inverse Fourier transformation. By analyzing the drift of interference spectra, the temperature response sensitivities of 0.063 nm/°C, 0.071 nm/°C, and 0.059 nm/°C in different furnaces can be detected from room temperature up to 1000 °C, and the temperature response at different regions can be measured through the sensitivity matrix equation. These results demonstrate feasibility of multipoint measurement, which also support that the temperature sensing system provides new solution to the MZI cascade problem. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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17 pages, 3636 KiB

Open AccessArticle

Metal Contamination Distribution Detection in High-Voltage Transmission Line Insulators by Laser-induced Breakdown Spectroscopy (LIBS)

by Naixiao Wang, Xilin Wang, Ping Chen, Zhidong Jia, Liming Wang, Ronghui Huang and Qishen Lv

Sensors 2018, 18(8), 2623; https://doi.org/10.3390/s18082623 - 10 Aug 2018

Cited by 28 | Viewed by 4130

Abstract

The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the [...] Read more.

The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the samples back to the lab and then testing them with elemental analysis equipment, especially for sugars, bird droppings, and heavy metal particulates, which cannot be analysed by the equivalent salt deposit density (ESDD) or non-soluble deposit density (NSDD) methods. In this study, a novel method called laser-induced breakdown spectroscopy (LIBS) offering the advantages of no sample preparation, being nearly nondestructive and having a fast speed was applied for the analysis of metal contamination. Several LIBS parameters (laser energy and delay time) were optimized to obtain better resolution of the spectral data. The limit of detection (LOD) of the observed elements was obtained using a calibration curve. Compared to calibration curves, multivariate analysis methods including principal component analysis (PCA), k-means and partial least squares regression (PLSR) showed their superiority in analyzing metal contamination in insulators. Then, the elemental distribution of natural pollution was predicted using LIBS to fully capture information about the bulk elements (Na, Ni, Cu, Mn, Ca, etc.) of entire areas with PLSR. The results showed that LIBS could be a promising method for accurate direct online quantification of metal contamination in insulators. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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10 pages, 4937 KiB

Open AccessArticle

Radiation-Resistant Er³⁺-Doped Superfluorescent Fiber Sources

by Chengxiang Liu, Xu Wu, Jianhui Zhu, Nie He, Zhuoyan Li, Gongshen Zhang, Li Zhang and Shuangchen Ruan

Sensors 2018, 18(7), 2236; https://doi.org/10.3390/s18072236 - 11 Jul 2018

Cited by 7 | Viewed by 3301

Abstract

The radiation effects of three Er³⁺-doped superfluorescent fiber sources (SFSs), which are based on three segments of Er-doped fibers with different lengths, are studied experimentally. We observed that the radiation-induced attenuation of the signal light of the 1530 nm band for [...] Read more.

The radiation effects of three Er³⁺-doped superfluorescent fiber sources (SFSs), which are based on three segments of Er-doped fibers with different lengths, are studied experimentally. We observed that the radiation-induced attenuation of the signal light of the 1530 nm band for an SFS is less than that of the 1560 nm band. Thus, the trimming technique of the Gauss-like spectra is investigated to reduce the mean wavelength drift. A filter was customized and used in superfluorescent fiber sources. To further reduce output power loss, the method with feedback control of pump power was adopted in the SFS. Then, the trimming spectral SFS with pump feedback control was tested under irradiation environment at the dose rate of 2.988 Gy/h. The experimental results demonstrate that the mean wavelength drift is <40 ppm and the loss of output power is <0.2 dB under a total dose higher than 1000 Gy. These findings confirm the significance of the method in improving radiation-resistant capabilities of fiber sources under irradiation environments. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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12 pages, 3382 KiB

Open AccessArticle

Determination of the Maximum Temperature in a Non-Uniform Hot Zone by Line-of-Site Absorption Spectroscopy with a Single Diode Laser

by Vladimir V. Liger, Vladimir R. Mironenko, Yurii A. Kuritsyn and Mikhail A. Bolshov

Sensors 2018, 18(5), 1608; https://doi.org/10.3390/s18051608 - 17 May 2018

Cited by 11 | Viewed by 3796

Abstract

A new algorithm for the estimation of the maximum temperature in a non-uniform hot zone by a sensor based on absorption spectrometry with a diode laser is developed. The algorithm is based on the fitting of the absorption spectrum with a test molecule [...] Read more.

A new algorithm for the estimation of the maximum temperature in a non-uniform hot zone by a sensor based on absorption spectrometry with a diode laser is developed. The algorithm is based on the fitting of the absorption spectrum with a test molecule in a non-uniform zone by linear combination of two single temperature spectra simulated using spectroscopic databases. The proposed algorithm allows one to better estimate the maximum temperature of a non-uniform zone and can be useful if only the maximum temperature rather than a precise temperature profile is of primary interest. The efficiency and specificity of the algorithm are demonstrated in numerical experiments and experimentally proven using an optical cell with two sections. Temperatures and water vapor concentrations could be independently regulated in both sections. The best fitting was found using a correlation technique. A distributed feedback (DFB) diode laser in the spectral range around 1.343 µm was used in the experiments. Because of the significant differences between the temperature dependences of the experimental and theoretical absorption spectra in the temperature range 300–1200 K, a database was constructed using experimentally detected single temperature spectra. Using the developed algorithm the maximum temperature in the two-section cell was estimated with accuracy better than 30 K. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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13 pages, 2037 KiB

Open AccessArticle

Construction and Functionality of a Ceramic Resonant Pressure Sensor for Operation at Elevated Temperatures

by Matej Sadl, Andraz Bradesko, Darko Belavic, Andreja Bencan, Barbara Malic and Tadej Rojac

Sensors 2018, 18(5), 1423; https://doi.org/10.3390/s18051423 - 3 May 2018

Cited by 7 | Viewed by 4728

Abstract

Piezoelectric ceramic resonant pressure sensors have shown potential as sensing elements for harsh environments, such as elevated temperatures. For operating temperatures exceeding ~250 °C, conventional and widely used Pb(Zr,Ti)O₃ (PZT) piezoelectrics should be replaced. Here, a ceramic pressure sensor from low-temperature co-fired [...] Read more.

Piezoelectric ceramic resonant pressure sensors have shown potential as sensing elements for harsh environments, such as elevated temperatures. For operating temperatures exceeding ~250 °C, conventional and widely used Pb(Zr,Ti)O₃ (PZT) piezoelectrics should be replaced. Here, a ceramic pressure sensor from low-temperature co-fired ceramics (LTCC) was constructed by integrating a piezoelectric actuator made from bismuth ferrite (BiFeO₃) on a diaphragm. This ferroelectric material was selected because of its high Curie temperature (T_C = 825 °C) and as a lead-free piezoelectric extensively investigated for high-temperature applications. In order to construct a sensor with suitable pressure sensitivity, numerical simulations were used to define the optimum construction dimensions. The functionality of the pressure sensor was tested up to 201 °C. The measurements confirmed a pressure sensitivity, i.e., resonance frequency shift of the sensor per unit of pressure, of −8.7 Hz/kPa up to 171 °C. It was suggested that the main reason for the hindered operation at the elevated temperatures could lie in the thermo-mechanical properties of the diaphragm and the adhesive bonding at the actuator-diaphragm interconnection. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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13 pages, 6367 KiB

Open AccessArticle

Substrate Integrated Waveguide (SIW)-Based Wireless Temperature Sensor for Harsh Environments

by Qiulin Tan, Yanjie Guo, Lei Zhang, Fei Lu, Helei Dong and Jijun Xiong

Sensors 2018, 18(5), 1406; https://doi.org/10.3390/s18051406 - 3 May 2018

Cited by 21 | Viewed by 5299

Abstract

This paper presents a new wireless sensor structure based on a substrate integrated circular waveguide (SICW) for the temperature test in harsh environments. The sensor substrate material is 99% alumina ceramic, and the SICW structure is composed of upper and lower metal plates [...] Read more.

This paper presents a new wireless sensor structure based on a substrate integrated circular waveguide (SICW) for the temperature test in harsh environments. The sensor substrate material is 99% alumina ceramic, and the SICW structure is composed of upper and lower metal plates and a series of metal cylindrical sidewall vias. A rectangular aperture antenna integrated on the surface of the SICW resonator is used for electromagnetic wave transmission between the sensor and the external antenna. The resonant frequency of the temperature sensor decreases when the temperature increases, because the relative permittivity of the alumina ceramic increases with temperature. The temperature sensor presented in this paper was tested four times at a range of 30–1200 °C, and a broad band coplanar waveguide (CPW)-fed antenna was used as an interrogation antenna during the test process. The resonant frequency changed from 2.371 to 2.141 GHz as the temperature varied from 30 to 1200 °C, leading to a sensitivity of 0.197 MHz/°C. The quality factor of the sensor changed from 3444.6 to 35.028 when the temperature varied from 30 to 1000 °C. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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9 pages, 10191 KiB

Open AccessArticle

A Highly Thermostable In₂O₃/ITO Thin Film Thermocouple Prepared via Screen Printing for High Temperature Measurements

by Yantao Liu, Wei Ren, Peng Shi, Dan Liu, Yijun Zhang, Ming Liu, Zuo-Guang Ye, Weixuan Jing, Bian Tian and Zhuangde Jiang

Sensors 2018, 18(4), 958; https://doi.org/10.3390/s18040958 - 23 Mar 2018

Cited by 51 | Viewed by 6348

Abstract

An In₂O₃/ITO thin film thermocouple was prepared via screen printing. Glass additives were added to improve the sintering process and to increase the density of the In₂O₃/ITO films. The surface and cross-sectional images indicate that [...] Read more.

An In₂O₃/ITO thin film thermocouple was prepared via screen printing. Glass additives were added to improve the sintering process and to increase the density of the In₂O₃/ITO films. The surface and cross-sectional images indicate that both the grain size and densification of the ITO and In₂O₃ films increased with the increase in annealing time. The thermoelectric voltage of the In₂O₃/ITO thermocouple was 53.5 mV at 1270 °C at the hot junction. The average Seebeck coefficient of the thermocouple was calculated as 44.5 μV/°C. The drift rate of the In₂O₃/ITO thermocouple was 5.44 °C/h at a measuring time of 10 h at 1270 °C. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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12 pages, 10983 KiB

Open AccessArticle

A Manganin Thin Film Ultra-High Pressure Sensor for Microscale Detonation Pressure Measurement

by Guodong Zhang, Yulong Zhao, Yun Zhao, Xinchen Wang, Xueyong Wei, Wei Ren, Hui Li and You Zhao

Sensors 2018, 18(3), 736; https://doi.org/10.3390/s18030736 - 1 Mar 2018

Cited by 11 | Viewed by 7746

Abstract

With the development of energetic materials (EMs) and microelectromechanical systems (MEMS) initiating explosive devices, the measurement of detonation pressure generated by EMs in the microscale has become a pressing need. This paper develops a manganin thin film ultra-high pressure sensor based on MEMS [...] Read more.

With the development of energetic materials (EMs) and microelectromechanical systems (MEMS) initiating explosive devices, the measurement of detonation pressure generated by EMs in the microscale has become a pressing need. This paper develops a manganin thin film ultra-high pressure sensor based on MEMS technology for measuring the output pressure from micro-detonator. A reliable coefficient is proposed for designing the sensor’s sensitive element better. The sensor employs sandwich structure: the substrate uses a 0.5 mm thick alumina ceramic, the manganin sensitive element with a size of 0.2 mm × 0.1 mm × 2 μm and copper electrodes of 2 μm thick are sputtered sequentially on the substrate, and a 25 μm thick insulating layer of polyimide is wrapped on the sensitive element. The static test shows that the piezoresistive coefficient of manganin thin film is 0.0125 GPa⁻¹. The dynamic experiment indicates that the detonation pressure of micro-detonator is 12.66 GPa, and the response time of the sensor is 37 ns. In a word, the sensor developed in this study is suitable for measuring ultra-high pressure in microscale and has a shorter response time than that of foil-like manganin gauges. Simultaneously, this study could be beneficial to research on ultra-high-pressure sensors with smaller size. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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20 pages, 10735 KiB

Open AccessArticle

The Prediction of the Gas Utilization Ratio based on TS Fuzzy Neural Network and Particle Swarm Optimization

by Sen Zhang, Haihe Jiang, Yixin Yin, Wendong Xiao and Baoyong Zhao

Sensors 2018, 18(2), 625; https://doi.org/10.3390/s18020625 - 20 Feb 2018

Cited by 42 | Viewed by 4741

Abstract

Gas utilization ratio (GUR) is an important indicator that is used to evaluate the energy consumption of blast furnaces (BFs). Currently, the existing methods cannot predict the GUR accurately. In this paper, we present a novel data-driven model for predicting the GUR. The [...] Read more.

Gas utilization ratio (GUR) is an important indicator that is used to evaluate the energy consumption of blast furnaces (BFs). Currently, the existing methods cannot predict the GUR accurately. In this paper, we present a novel data-driven model for predicting the GUR. The proposed approach utilized both the TS fuzzy neural network (TS-FNN) and the particle swarm algorithm (PSO) to predict the GUR. The particle swarm algorithm (PSO) is applied to optimize the parameters of the TS-FNN in order to decrease the error caused by the inaccurate initial parameter. This paper also applied the box graph (Box-plot) method to eliminate the abnormal value of the raw data during the data preprocessing. This method can deal with the data which does not obey the normal distribution which is caused by the complex industrial environments. The prediction results demonstrate that the optimization model based on PSO and the TS-FNN approach achieves higher prediction accuracy compared with the TS-FNN model and SVM model and the proposed approach can accurately predict the GUR of the blast furnace, providing an effective way for the on-line blast furnace distribution control. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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14 pages, 6065 KiB

Open AccessArticle

Low-Cost Wireless Temperature Measurement: Design, Manufacture, and Testing of a PCB-Based Wireless Passive Temperature Sensor

by Dan Yan, Yong Yang, Yingping Hong, Ting Liang, Zong Yao, Xiaoyong Chen and Jijun Xiong

Sensors 2018, 18(2), 532; https://doi.org/10.3390/s18020532 - 10 Feb 2018

Cited by 31 | Viewed by 8725

Abstract

Low-cost wireless temperature measurement has significant value in the food industry, logistics, agriculture, portable medical equipment, intelligent wireless health monitoring, and many areas in everyday life. A wireless passive temperature sensor based on PCB (Printed Circuit Board) materials is reported in this paper. [...] Read more.

Low-cost wireless temperature measurement has significant value in the food industry, logistics, agriculture, portable medical equipment, intelligent wireless health monitoring, and many areas in everyday life. A wireless passive temperature sensor based on PCB (Printed Circuit Board) materials is reported in this paper. The advantages of the sensor include simple mechanical structure, convenient processing, low-cost, and easiness in integration. The temperature-sensitive structure of the sensor is a dielectric-loaded resonant cavity, consisting of the PCB substrate. The sensitive structure also integrates a patch antenna for the transmission of temperature signals. The temperature sensing mechanism of the sensor is the dielectric constant of the PCB substrate changes with temperature, which causes the resonant frequency variation of the resonator. Then the temperature can be measured by detecting the changes in the sensor’s working frequency. The PCB-based wireless passive temperature sensor prototype is prepared through theoretical design, parameter analysis, software simulation, and experimental testing. The high- and low-temperature sensing performance of the sensor is tested, respectively. The resonant frequency decreases from 2.434 GHz to 2.379 GHz as the temperature increases from −40 °C to 125 °C. The fitting curve proves that the experimental data have good linearity. Three repetitive tests proved that the sensor possess well repeatability. The average sensitivity is

347.45 KHz / ℃

from repetitive measurements conducted three times. This study demonstrates the feasibility of the PCB-based wireless passive sensor, which provides a low-cost temperature sensing solution for everyday life, modern agriculture, thriving intelligent health devices, and so on, and also enriches PCB product lines and applications. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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13 pages, 7580 KiB

Open AccessArticle

Underwater Object Segmentation Based on Optical Features

by Zhe Chen, Zhen Zhang, Yang Bu, Fengzhao Dai, Tanghuai Fan and Huibin Wang

Sensors 2018, 18(1), 196; https://doi.org/10.3390/s18010196 - 12 Jan 2018

Cited by 24 | Viewed by 5134

Abstract

Underwater optical environments are seriously affected by various optical inputs, such as artificial light, sky light, and ambient scattered light. The latter two can block underwater object segmentation tasks, since they inhibit the emergence of objects of interest and distort image information, while [...] Read more.

Underwater optical environments are seriously affected by various optical inputs, such as artificial light, sky light, and ambient scattered light. The latter two can block underwater object segmentation tasks, since they inhibit the emergence of objects of interest and distort image information, while artificial light can contribute to segmentation. Artificial light often focuses on the object of interest, and, therefore, we can initially identify the region of target objects if the collimation of artificial light is recognized. Based on this concept, we propose an optical feature extraction, calculation, and decision method to identify the collimated region of artificial light as a candidate object region. Then, the second phase employs a level set method to segment the objects of interest within the candidate region. This two-phase structure largely removes background noise and highlights the outline of underwater objects. We test the performance of the method with diverse underwater datasets, demonstrating that it outperforms previous methods. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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13 pages, 4985 KiB

Open AccessArticle

Electromagnetic Acoustic Transducers for Robotic Nondestructive Inspection in Harsh Environments

by Sungho Choi, Hwanjeong Cho, Matthew S. Lindsey and Cliff J. Lissenden

Sensors 2018, 18(1), 193; https://doi.org/10.3390/s18010193 - 11 Jan 2018

Cited by 25 | Viewed by 6222

Abstract

Elevated temperature, gamma radiation, and geometric constraints inside dry storage casks for spent nuclear fuel represent a harsh environment for nondestructive inspection of the cask and require that the inspection be conducted with a robotic system. Electromagnetic acoustic transducers (EMATs) using non-contact ultrasonic [...] Read more.

Elevated temperature, gamma radiation, and geometric constraints inside dry storage casks for spent nuclear fuel represent a harsh environment for nondestructive inspection of the cask and require that the inspection be conducted with a robotic system. Electromagnetic acoustic transducers (EMATs) using non-contact ultrasonic transduction based on the Lorentz force to excite/receive ultrasonic waves are suited for use in the robotic inspection. Periodic permanent magnet EMATs that actuate/receive shear horizontal guided waves are developed for application to robotic nondestructive inspection of stress corrosion cracks in the heat affected zone of welds in stainless steel dry storage canisters. The EMAT’s components are carefully selected in consideration of the inspection environment, and tested under elevated temperature and gamma radiation doses up to 177 °C and 5920 krad, respectively, to evaluate the performance of the EMATs under realistic environmental conditions. The effect of gamma radiation is minimal, but the EMAT’s performance is affected by temperatures above 121 °C due to the low Curie temperature of the magnets. Different magnets are needed to operate at 177 °C. The EMAT’s capability to detect notches is also evaluated from B-scan measurements on 304 stainless steel welded plate containing surface-breaking notches. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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5805 KiB

Open AccessArticle

First Results of Using a UVTron Flame Sensor to Detect Alpha-Induced Air Fluorescence in the UVC Wavelength Range

by Anita J. Crompton, Kelum A. A. Gamage, Steven Bell, Andrew P. Wilson, Alex Jenkins and Divyesh Trivedi

Sensors 2017, 17(12), 2756; https://doi.org/10.3390/s17122756 - 29 Nov 2017

Cited by 16 | Viewed by 6149

Abstract

In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source [...] Read more.

In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source of the alpha emissions. This paper details experiments carried out to detect this fluorescence, with the focus on photons in the ultraviolet C (UVC) wavelength range (180–280 nm). A detector, UVTron R9533 (Hamamatsu, 325-6, Sunayama-cho, Naka-ku, Hamamatsu City, Shizuoka Pref., 430-8587, Japan), designed to detect the UVC emissions from flames for fire alarm purposes, was tested in various gas atmospheres with a ²¹⁰Po alpha source to determine if this could provide an avenue for stand-off alpha detection. The results of the experiments show that this detector is capable of detecting alpha-induced air fluorescence in normal indoor lighting conditions, as the interference from daylight and artificial lighting is less influential on this detection system which operates below the UVA and UVB wavelength ranges (280–315 nm and 315–380 nm respectively). Assuming a standard

\frac{1}{r^{2}}

drop off in signal, the limit of detection in this configuration can be calculated to be approximately 240 mm, well beyond the range of alpha-particles in air, which indicates that this approach could have potential for stand-off alpha detection. The gas atmospheres tested produced an increase in the detector count, with xenon having the greatest effect with a measured 52% increase in the detector response in comparison to the detector response in an air atmosphere. This type of alpha detection system could be operated at a distance, where it would potentially provide a more cost effective, safer, and faster solution in comparison with traditional alpha detection methods to detect and characterise alpha contamination in nuclear decommissioning and security applications. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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2701 KiB

Open AccessArticle

A High-Temperature MEMS Surface Fence for Wall-Shear-Stress Measurement in Scramjet Flow

by Chengyu Ma, Binghe Ma, Jinjun Deng, Weizheng Yuan, Zitong Zhou and Han Zhang

Sensors 2017, 17(10), 2412; https://doi.org/10.3390/s17102412 - 22 Oct 2017

Cited by 1 | Viewed by 5891

Abstract

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 [...] Read more.

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 °C. The packaged sensor is calibrated over a range of ~65 Pa and then used to examine the development of the transient flow of the scramjet ignition process (Mach 2 airflow, stagnation pressure, and a temperature of 0.8 MPa and 950 K, respectively). The results show that the sensor is able to detect the transient flow conditions of the scramjet ignition process including shock impact, flow correction, steady state, and hydrogen off. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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4851 KiB

Open AccessArticle

The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm²

by Lin-Yue Liu, Ling Wang, Peng Jin, Jin-Liang Liu, Xian-Peng Zhang, Liang Chen, Jiang-Fu Zhang, Xiao-Ping Ouyang, Ao Liu, Run-Hua Huang and Song Bai

Sensors 2017, 17(10), 2334; https://doi.org/10.3390/s17102334 - 13 Oct 2017

Cited by 23 | Viewed by 6669

Abstract

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response [...] Read more.

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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2650 KiB

Open AccessCommunication

Autonomous Microsystems for Downhole Applications: Design Challenges, Current State, and Initial Test Results

by Myungjoon Choi, Yu Sui, In Hee Lee, Ryan Meredith, Yushu Ma, Gyouho Kim, David Blaauw, Yogesh B. Gianchandani and Tao Li

Sensors 2017, 17(10), 2190; https://doi.org/10.3390/s17102190 - 23 Sep 2017

Cited by 13 | Viewed by 7077

Abstract

This paper describes two platforms for autonomous sensing microsystems that are intended for deployment in chemically corrosive environments at elevated temperatures and pressures. Following the deployment period, the microsystems are retrieved, recharged, and interrogated wirelessly at close proximity. The first platform is the [...] Read more.

This paper describes two platforms for autonomous sensing microsystems that are intended for deployment in chemically corrosive environments at elevated temperatures and pressures. Following the deployment period, the microsystems are retrieved, recharged, and interrogated wirelessly at close proximity. The first platform is the Michigan Micro Mote for High Temperature (M³HT), a chip stack 2.9 × 1.1 × 1.5 mm³ in size. It uses RF communications to support pre-deployment and post-retrieval functions, and it uses customized electronics to achieve ultralow power consumption, permitting the use of a chip-scale battery. The second platform is the Environmental Logging Microsystem (ELM). This system, which is 6.5 × 6.3 × 4.5 mm³ in size, uses the smallest suitable off-the-shelf electronic and battery components that are compatible with assembly on a flexible printed circuit board. Data are stored in non-volatile memory, permitting retrieval even after total power loss. Pre-deployment and post-retrieval functions are supported by optical communication. Two types of encapsulation methods are used to withstand high pressure and corrosive environments: an epoxy filled volume is used for the M³HT, and a hollow stainless-steel shell with a sapphire lid is used for both the M³HT and ELM. The encapsulated systems were successfully tested at temperature and pressure reaching 150 °C and 10,000 psi, in environments of concentrated brine, oil, and cement slurry. At elevated temperatures, the limited lifetimes of available batteries constrain the active deployment period to several hours. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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Review

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12 pages, 2590 KiB

Open AccessFeature PaperReview

Update of Single Event Effects Radiation Hardness Assurance of Readout Integrated Circuit of Infrared Image Sensors at Cryogenic Temperature

by Laurent Artola, Ahmad Al Youssef, Samuel Ducret, Franck Perrier, Raphael Buiron, Olivier Gilard, Julien Mekki, Mathieu Boutillier, Guillaume Hubert and Christian Poivey

Sensors 2018, 18(7), 2338; https://doi.org/10.3390/s18072338 - 18 Jul 2018

Cited by 7 | Viewed by 4358

Abstract

This paper review presents Single Event Effects (SEE) irradiation tests under heavy ions of the test-chip of D-Flip-Flop (DFF) cells and complete readout integrated circuits (ROIC) as a function of temperature, down to 50 K. The analyses of the experimental data are completed [...] Read more.

This paper review presents Single Event Effects (SEE) irradiation tests under heavy ions of the test-chip of D-Flip-Flop (DFF) cells and complete readout integrated circuits (ROIC) as a function of temperature, down to 50 K. The analyses of the experimental data are completed using the SEE prediction tool MUSCA SEP3. The conclusions derived from the experimental measurements and related analyses allow to update the current SEE radiation hardness assurance (RHA) for readout integrated circuits of infrared image sensors used at cryogenic temperatures. The current RHA update is performed on SEE irradiation tests at room temperature, as opposed to the operational cryogenic temperature. These tests include SET (Single Event Transient), SEU (Single Event Upset) and SEFI (Single Event Functional Interrupt) irradiation tests. This update allows for reducing the cost of ROIC qualifications and the test setup complexity for each space mission. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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23 pages, 4833 KiB

Open AccessReview

Alpha Particle Detection Using Alpha-Induced Air Radioluminescence: A Review and Future Prospects for Preliminary Radiological Characterisation for Nuclear Facilities Decommissioning

by Anita J. Crompton, Kelum A. A. Gamage, Alex Jenkins and Charles James Taylor

Sensors 2018, 18(4), 1015; https://doi.org/10.3390/s18041015 - 28 Mar 2018

Cited by 23 | Viewed by 8952

Abstract

The United Kingdom (UK) has a significant legacy of nuclear installations to be decommissioned over the next 100 years and a thorough characterisation is required prior to the development of a detailed decommissioning plan. Alpha radiation detection is notoriously time consuming and difficult [...] Read more.

The United Kingdom (UK) has a significant legacy of nuclear installations to be decommissioned over the next 100 years and a thorough characterisation is required prior to the development of a detailed decommissioning plan. Alpha radiation detection is notoriously time consuming and difficult to carry out due to the short range of alpha particles in air. Long-range detection of alpha particles is therefore highly desirable and this has been attempted through the detection of secondary effects from alpha radiation, most notably the air-radioluminescence caused by ionisation. This paper evaluates alpha induced air radioluminescence detectors developed to date and looks at their potential to develop a stand-off, alpha radiation detector which can be used in the nuclear decommissioning field in daylight conditions to detect alpha contaminated materials. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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4743 KiB

Open AccessReview

Thermal Flow Sensors for Harsh Environments

by Vivekananthan Balakrishnan, Hoang-Phuong Phan, Toan Dinh, Dzung Viet Dao and Nam-Trung Nguyen

Sensors 2017, 17(9), 2061; https://doi.org/10.3390/s17092061 - 8 Sep 2017

Cited by 72 | Viewed by 15444

Abstract

Flow sensing in hostile environments is of increasing interest for applications in the automotive, aerospace, and chemical and resource industries. There are thermal and non-thermal approaches for high-temperature flow measurement. Compared to their non-thermal counterparts, thermal flow sensors have recently attracted a great [...] Read more.

Flow sensing in hostile environments is of increasing interest for applications in the automotive, aerospace, and chemical and resource industries. There are thermal and non-thermal approaches for high-temperature flow measurement. Compared to their non-thermal counterparts, thermal flow sensors have recently attracted a great deal of interest due to the ease of fabrication, lack of moving parts and higher sensitivity. In recent years, various thermal flow sensors have been developed to operate at temperatures above 500 °C. Microelectronic technologies such as silicon-on-insulator (SOI), and complementary metal-oxide semiconductor (CMOS) have been used to make thermal flow sensors. Thermal sensors with various heating and sensing materials such as metals, semiconductors, polymers and ceramics can be selected according to the targeted working temperature. The performance of these thermal flow sensors is evaluated based on parameters such as thermal response time, flow sensitivity. The data from thermal flow sensors reviewed in this paper indicate that the sensing principle is suitable for the operation under harsh environments. Finally, the paper discusses the packaging of the sensor, which is the most important aspect of any high-temperature sensing application. Other than the conventional wire-bonding, various novel packaging techniques have been developed for high-temperature application. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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