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Instrument and Measurement Based on Sensing Technology in China
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Instrument and Measurement Based on Sensing Technology in China

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 89496

Special Issue Editors

Prof. Dr. Xue Wang

E-Mail Website
Guest Editor
Department of Precision Instrument, Tsinghua University, Beijing 100084, China
Interests: intelligent sensors; sensors networks; remote sensing; intelligent signal processing; Kalman filtering; multisensor fusion; intelligent maintenance and fault prognosis; measurement instrumentation; robust and optimal control
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Xinyu Li

E-Mail Website
Guest Editor
State Key Lab Digital Mfg Equipment & Technology, Huazhong University of Science and Technology, Wuhan, China
Interests: intelligent manufacturing; deep learning; machine learning; fault diagnosis; surface defect recognition
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Liang Ren

E-Mail Website
Guest Editor
Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China
Interests: multi-sensor synchronous data acquisition for structural health monitoring; fiber Bragg grating sensor packaging technology; real-time structural health monitoring of pipelines
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Qi Zhou

E-Mail
Guest Editor
School of Automation, Guangdong University of Technology, Guangzhou 510006, China
Interests: fuzzy-logic control; neural control; robust control for nonlinear systems
Prof. Dr. Jikui Luo

E-Mail Website
Guest Editor
College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China
Interests: sensors and actuators; wireless sensors; wearable electronics; energy harvesting technology; self-powered electronics
Special Issues, Collections and Topics in MDPI journals
Dr. Lei Zhang

E-Mail Website
Guest Editor
1. Research Center for Intelligent Sensing, Zhejiang Lab, Hangzhou 310000, China
2. College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
Interests: optical micro/nanofiber sensors; tactile sensors; wearable sensors; microfluidic sensors; optofluidic sensors
Special Issues, Collections and Topics in MDPI journals
Dr. He Tian

grade E-Mail Website
Guest Editor
Institute of Microelectronics, Tsinghua University, Beijing 100084, China
Interests: sensors; graphene; actuator; 2D materials; nano devices
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Hongwei Liu

E-Mail Website
Guest Editor
National Lab of Radar Signal Processing, Xidian University, Shaanxi 710071, China
Interests: radar signal processing; radar target recognition; cognitive radar
Prof. Dr. Aiguo Song

E-Mail Website
Guest Editor
School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China
Interests: force/torque sensor; tactile sensor; robot sensor; sensor fusion; sensor networks
Prof. Dr. Xinming Li

E-Mail Website
Guest Editor
School of information and optoelectronic science and technology, South China Normal University, Guangzhou 510006, China
Interests: solid-state devices; wearable/implantable sensors; optoelectronics; mechanical sensors; biomimetic and artificial systems; electronic materials; graphene and carbon nanomaterials; 2D materials; electronic and ionic transport

Special Issue Information

This Special Issue aims to provide a comprehensive overview of new developments and advancements in the fields of sensor, instrument, and measurement technologies in China. We intend to cover all technical contents, applications, and multidisciplinary aspects of the field, embedded in, but not limited to, the following areas:

Spatial variables;
Displacement;
Mechanics, Mechanical variables;
Continuum mechanics;
Acoustics;
Flow and spot velocity;
Electrical variables;
Electromagnetic variables;
Thermal and temperature;
Radiation, rays, waves, and particles;
Optical measurement
Energy and power;
Displays and recorders;
Control, automation, and manufacture;
Time and frequency;
Wireless measurement and instruments;
Telemetry;
Chemical variables;
Materials, crystal and their properties
Medical, biomedical, and health variables;
Human senses and the human body;
Environment;
Meteorology;
Navigation and surveying;
Astronomy;
Strucatral Health Monitoring;
Force/torque measurement;
Tactile measurement;

Published Papers (29 papers)

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12 pages, 2263 KiB  
Article
A Fault Diagnosis System for a Pipeline Robot Based on Sound Signal Recognition
by Hai Cao, Jinpeng Yu, Yu Wang, Liang Zhang and Jongwon Kim
Sensors 2022, 22(9), 3275; https://doi.org/10.3390/s22093275 - 24 Apr 2022
Cited by 5 | Viewed by 2322
Abstract
Timely and accurate identification of fault types at the early stage of minor faults is significant for cutting off fault evolution. In order to have a clear understanding of the pipeline robot’s own situation in the pipeline, this paper proposes a fault diagnosis [...] Read more.
Timely and accurate identification of fault types at the early stage of minor faults is significant for cutting off fault evolution. In order to have a clear understanding of the pipeline robot’s own situation in the pipeline, this paper proposes a fault diagnosis system for pipeline robots based on sound signal recognition. This can effectively reduce the probability of serious faults such as shutdown and loss of control in the pipeline without affecting the safe operation of the pipeline robot, which is a key issue to improve the reliability of the pipeline robot. The system consists of a combination of three parts: hardware, software, and algorithm. On the one hand, Raspberry Pi is the core module, while on the other hand, it is also responsible for the data transmission between the various modules, including storing the original sound signals collected by the sensors and transmitting the diagnosis results to the upper computer software interface. The proposed system is validated on the dataset collected by the data experimentation platform. The experimental results show that the proposed fault prediction method obtains advanced results on this dataset, verifying the effectiveness and stability of the proposed fault diagnosis system for pipeline robots based on sound signal recognition. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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14 pages, 2683 KiB  
Article
Monitoring and Predictive Maintenance of Centrifugal Pumps Based on Smart Sensors
by Lei Chen, Lijun Wei, Yu Wang, Junshuo Wang and Wenlong Li
Sensors 2022, 22(6), 2106; https://doi.org/10.3390/s22062106 - 09 Mar 2022
Cited by 15 | Viewed by 9340
Abstract
Centrifugal pumps have a wide range of applications in industrial and municipal water affairs. During the use of centrifugal pumps, failures such as bearing wear, blade damage, impeller imbalance, shaft misalignment, cavitation, water hammer, etc., often occur. It is of great importance to [...] Read more.
Centrifugal pumps have a wide range of applications in industrial and municipal water affairs. During the use of centrifugal pumps, failures such as bearing wear, blade damage, impeller imbalance, shaft misalignment, cavitation, water hammer, etc., often occur. It is of great importance to use smart sensors and digital Internet of Things (IoT) systems to monitor the real-time operating status of pumps and predict potential failures for achieving predictive maintenance of pumps and improving the intelligence level of machine health management. Firstly, the common fault forms of centrifugal pumps and the characteristics of vibration signals when a fault occurs are introduced. Secondly, the centrifugal pump monitoring IoT system is designed. The system is mainly composed of wireless sensors, wired sensors, data collectors, and cloud servers. Then, the microelectromechanical system (MEMS) chip is used to design a wireless vibration temperature integrated sensor, a wired vibration temperature integrated sensor, and a data collector to monitor the running state of the pump. The designed wireless sensor communicates with the server through Narrow Band Internet of Things (NB-IoT). The output of the wired sensor is connected to the data collector, and the designed collector can communicate with the server through 4G communication. Through cloud-side collaboration, real-time monitoring of the running status of centrifugal pumps and intelligent diagnosis of centrifugal pump faults are realized. Finally, on-site testing and application verification of the system was conducted. The test results show that the designed sensors and sensor application system can make good use of the centrifugal pump failure mechanism to automatically diagnose equipment failures. Moreover, the diagnostic accuracy rate is above 85% by using the method of wired sensor and collector. As a low-cost and easy-to-implement solution, wireless sensors can also monitor gradual failures well. The research on the sensors and pump monitoring system provides feasible methods and an effective means for the application of centrifugal pump health management and predictive maintenance. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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17 pages, 2762 KiB  
Article
Research on Small Sample Dynamic Human Ear Recognition Based on Deep Learning
by Yanmin Lei, Junru Qian, Dong Pan and Tingfa Xu
Sensors 2022, 22(5), 1718; https://doi.org/10.3390/s22051718 - 22 Feb 2022
Cited by 8 | Viewed by 2081
Abstract
Due to the problem of insufficient dynamic human ear data, the Changchun University dynamic human ear (CCU-DE) database, which is a small sample human ear database, was developed in this study. The database fully considers the various complex situations and posture changes of [...] Read more.
Due to the problem of insufficient dynamic human ear data, the Changchun University dynamic human ear (CCU-DE) database, which is a small sample human ear database, was developed in this study. The database fully considers the various complex situations and posture changes of human ear images, such as translation angle, rotation angle, illumination change, occlusion and interference, etc., making the research of dynamic human ear recognition closer to complex real-life situations, and increasing the applicability of human ear dynamic recognition. In order to test the practicability and effectiveness of the developed CCU-DE small sample database, we designed a dynamic human ear recognition system block diagram based on a deep learning model, which was pre-trained by a migration learning method. Aiming at multi-posture changes under different contrasts, translation and rotation motions, and with or without occlusion, simulation studies were conducted using the CCU-DE small sample database and different deep learning models, such as YOLOv3, YOLOv4, YOLOv5, Faster R-CNN, and SSD. The experimental results showed that the CCU-DE database can be well used for dynamic ear recognition, and it can be tested by using different deep learning models with higher test accuracy. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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25 pages, 4266 KiB  
Article
The Diverse Gait Dataset: Gait Segmentation Using Inertial Sensors for Pedestrian Localization with Different Genders, Heights and Walking Speeds
by Chao Huang, Fuping Zhang, Zhengyi Xu and Jianming Wei
Sensors 2022, 22(4), 1678; https://doi.org/10.3390/s22041678 - 21 Feb 2022
Cited by 14 | Viewed by 3960
Abstract
Stride length estimation is one of the most crucial aspects of Pedestrian Dead Reckoning (PDR). Due to the measurement noise of inertial sensors, individual variances of pedestrians, and the uncertainty in pedestrians walking, there is a substantial error in the assessment of stride [...] Read more.
Stride length estimation is one of the most crucial aspects of Pedestrian Dead Reckoning (PDR). Due to the measurement noise of inertial sensors, individual variances of pedestrians, and the uncertainty in pedestrians walking, there is a substantial error in the assessment of stride length, which causes the accumulated deviation of Pedestrian Dead Reckoning (PDR). With the help of multi-gait analysis, which decomposes strides in time and space with greater detail and accuracy, a novel and revolutionary stride estimating model or scheme could improve the performance of PDR on different users. This paper presents a diverse stride gait dataset by using inertial sensors that collect foot movement data from people of different genders, heights, and walking speeds. The dataset contains 4690 walking strides data and 19,083 gait labels. Based on the dataset, we propose a threshold-independent stride segmentation algorithm called SDATW and achieve an F-measure of 0.835. We also provide the detailed results of recognizing four gaits under different walking speeds, demonstrating the utility of our dataset for helping train stride segmentation algorithms and gait detection algorithms. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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24 pages, 966 KiB  
Article
An Energy-Efficient Routing Algorithm Based on Greedy Strategy for Energy Harvesting Wireless Sensor Networks
by Sheng Hao, Yong Hong and Yu He
Sensors 2022, 22(4), 1645; https://doi.org/10.3390/s22041645 - 19 Feb 2022
Cited by 16 | Viewed by 3107
Abstract
Energy harvesting wireless sensor network (EH-WSN) is considered to be one of the key enabling technologies for the internet of things (IoT) construction. Although the introduced EH technology can alleviate the energy limitation problem that occurs in the traditional wireless sensor network (WSN), [...] Read more.
Energy harvesting wireless sensor network (EH-WSN) is considered to be one of the key enabling technologies for the internet of things (IoT) construction. Although the introduced EH technology can alleviate the energy limitation problem that occurs in the traditional wireless sensor network (WSN), most of the current studies on EH-WSN fail to adequately consider the relationship between energy state and data buffer constraint, and thereby they do not address well the issues of energy efficiency and long end-to-end delay. In view of the above problems, a brand new greedy strategy-based energy-efficient routing protocol is proposed in this paper. Firstly, in the system modeling process, we construct an energy evaluation model, which comprehensively considers the energy harvesting, energy consumption and energy classification factors, to identify the energy state of node. Then, we establish a channel feature-based communication range judgment model to determine the transmission area of nodes. Combining these two models, a reception state adjustment mechanism is designed. It takes the buffer occupancy and the MAC layer protocol into account to adjust the data reception state of nodes. On this basis, we propose a greedy strategy-based routing algorithm. In addition, we also analyze the correctness and computational complexity of the proposed algorithm. Finally, we conduct extensive simulation experiments to show that our algorithm achieves optimum performance in energy consumption, packet delivery ratio, average hop count and end-to-end delay and acceptable performance in energy variance. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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16 pages, 23414 KiB  
Article
A Cascade Attention Based Facial Expression Recognition Network by Fusing Multi-Scale Spatio-Temporal Features
by Xiaoliang Zhu, Zili He, Liang Zhao, Zhicheng Dai and Qiaolai Yang
Sensors 2022, 22(4), 1350; https://doi.org/10.3390/s22041350 - 10 Feb 2022
Cited by 16 | Viewed by 3249
Abstract
The performance of a facial expression recognition network degrades obviously under situations of uneven illumination or partial occluded face as it is quite difficult to pinpoint the attention hotspots on the dynamically changing regions (e.g., eyes, nose, and mouth) as precisely as possible. [...] Read more.
The performance of a facial expression recognition network degrades obviously under situations of uneven illumination or partial occluded face as it is quite difficult to pinpoint the attention hotspots on the dynamically changing regions (e.g., eyes, nose, and mouth) as precisely as possible. To address the above issue, by a hybrid of the attention mechanism and pyramid feature, this paper proposes a cascade attention-based facial expression recognition network on the basis of a combination of (i) local spatial feature, (ii) multi-scale-stereoscopic spatial context feature (extracted from the 3-scale pyramid feature), and (iii) temporal feature. Experiments on the CK+, Oulu-CASIA, and RAF-DB datasets obtained recognition accuracy rates of 99.23%, 89.29%, and 86.80%, respectively. It demonstrates that the proposed method outperforms the state-of-the-art methods in both the experimental and natural environment. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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18 pages, 4841 KiB  
Article
Research on Position and Torque Loading System with Velocity-Sensitive and Adaptive Robust Control
by Zijia Li, Guangrong Chen and Chenyang Zhang
Sensors 2022, 22(4), 1329; https://doi.org/10.3390/s22041329 - 09 Feb 2022
Cited by 1 | Viewed by 1675
Abstract
In this paper, the research emphasis focuses on the tracking precision of position loading and torque loading systems with velocity-sensitive and adaptive robust control. Compared with conventional PID control, the improved PID control based on velocity-sensitive fully manifests its superiority to position loading. [...] Read more.
In this paper, the research emphasis focuses on the tracking precision of position loading and torque loading systems with velocity-sensitive and adaptive robust control. Compared with conventional PID control, the improved PID control based on velocity-sensitive fully manifests its superiority to position loading. By contrast, we analyzed the possible influence for the control difference of conventional PID and velocity-sensitive with PID. Furthermore, for the purpose of accurate torque loading, a mathematical model was established through dynamics analysis and the adaptive robust controller, where the adaptive robust control algorithm is designed to generate the reference position trajectory for the servo system in the upper controller while closed-loop position tracking is performed in the underlying controller, was built based on a state space equation. In the end, an experimental platform was built to verify the feasibility and advantages of the position and torque loading system with the velocity-sensitive and adaptive robust control. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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15 pages, 4630 KiB  
Article
A High Precision and Multifunctional Electro-Optical Conversion Efficiency Measurement System for Metamaterial-Based Thermal Emitters
by Heng Liu, Meng Zhao, Yongkang Gong, Kang Li, Cong Wang, Yuchen Wei, Jun Wang, Guozhen Liu, Jinlei Yao, Ying Li, Zheyi Li, Zhiqiang Gao and Ju Gao
Sensors 2022, 22(4), 1313; https://doi.org/10.3390/s22041313 - 09 Feb 2022
Cited by 1 | Viewed by 1981
Abstract
In this study, a multifunctional high-vacuum system was established to measure the electro-optical conversion efficiency of metamaterial-based thermal emitters with built-in heaters. The system is composed of an environmental control module, an electro-optical conversion measurement module, and a system control module. The system [...] Read more.
In this study, a multifunctional high-vacuum system was established to measure the electro-optical conversion efficiency of metamaterial-based thermal emitters with built-in heaters. The system is composed of an environmental control module, an electro-optical conversion measurement module, and a system control module. The system can provide air, argon, high vacuum, and other conventional testing environments, combined with humidity control. The test chamber and sample holder are carefully designed to minimize heat transfer through thermal conduction and convection. The optical power measurements are realized using the combination of a water-cooled KBr flange, an integrating sphere, and thermopile detectors. This structure is very stable and can detect light emission at the μW level. The system can synchronously detect the heating voltage, heating current, optical power, sample temperatures (both top and bottom), ambient pressure, humidity, and other environmental parameters. The comprehensive parameter detection capability enables the system to monitor subtle sample changes and perform failure mechanism analysis with the aid of offline material analysis using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, the system can be used for fatigue and high-low temperature impact tests. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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16 pages, 3866 KiB  
Article
Embedded Sensing System for Recognizing Citrus Flowers Using Cascaded Fusion YOLOv4-CF + FPGA
by Shilei Lyu, Yawen Zhao, Ruiyao Li, Zhen Li, Renjie Fan and Qiafeng Li
Sensors 2022, 22(3), 1255; https://doi.org/10.3390/s22031255 - 07 Feb 2022
Cited by 10 | Viewed by 2430
Abstract
Florescence information monitoring is essential for strengthening orchard management activities, such as flower thinning, fruit protection, and pest control. A lightweight object recognition model using cascade fusion YOLOv4-CF is proposed, which recognizes multi-type objects in their natural environments, such as citrus buds, citrus [...] Read more.
Florescence information monitoring is essential for strengthening orchard management activities, such as flower thinning, fruit protection, and pest control. A lightweight object recognition model using cascade fusion YOLOv4-CF is proposed, which recognizes multi-type objects in their natural environments, such as citrus buds, citrus flowers, and gray mold. The proposed model has an excellent representation capability with an improved cascade fusion network and a multi-scale feature fusion block. Moreover, separable deep convolution blocks were employed to enhance object feature information and reduce model computation. Further, channel shuffling was used to address missing recognition in the dense distribution of object groups. Finally, an embedded sensing system for recognizing citrus flowers was designed by quantitatively applying the proposed YOLOv4-CF model to an FPGA platform. The mAP@.5 of citrus buds, citrus flowers, and gray mold obtained on the server using the proposed YOLOv4-CF model was 95.03%, and the model size of YOLOv4-CF + FPGA was 5.96 MB, which was 74.57% less than the YOLOv4-CF model. The FPGA side had a frame rate of 30 FPS; thus, the embedded sensing system could meet the demands of florescence information in real-time monitoring. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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21 pages, 22034 KiB  
Article
An Experimental Study on Combustion and Cycle-by-Cycle Variations of an N-Butanol Engine with Hydrogen Direct Injection under Lean Burn Conditions
by Weiwei Shang, Xiumin Yu, Weibo Shi, Zhao Chen, Huiying Liu, He Yu, Xiaoxue Xing and Tingfa Xu
Sensors 2022, 22(3), 1229; https://doi.org/10.3390/s22031229 - 06 Feb 2022
Cited by 3 | Viewed by 1706
Abstract
This study experimentally investigated the effects of hydrogen direct injection on combustion and the cycle-by-cycle variations in a spark ignition n-butanol engine under lean burn conditions. For this purpose, a spark ignition engine installed with a hydrogen and n-butanol dual fuel injection system [...] Read more.
This study experimentally investigated the effects of hydrogen direct injection on combustion and the cycle-by-cycle variations in a spark ignition n-butanol engine under lean burn conditions. For this purpose, a spark ignition engine installed with a hydrogen and n-butanol dual fuel injection system was specially developed. Experiments were conducted at four excess air ratios, four hydrogen fractions(φ(𝐻2)) and pure n-butanol. Engine speed and intake manifold absolute pressure (MAP) were kept at 1500 r/min and 43 kPa, respectively. The results indicate that the θ0–10 and θ10–90 decreased gradually with the increase in hydrogen fraction. Additionally, the indicated mean effective pressure (IMEP), the peak cylinder pressure (Pmax) and the maximum rate of pressure rise ((dP/dφ)max) increased gradually, while their cycle-by-cycle variations decreased with the increase in hydrogen fraction. In addition, the correlation between the (dP/dφ)max and its corresponding crank angle became weak with the increase in the excess air coefficient (λ), which tends to be strongly correlated with the increase in hydrogen fraction. The coefficient of variation of the Pmax and the IMEP increased with the increase in λ, while they decreased obviously after blending in the hydrogen under lean burn conditions. Furthermore, when λ was 1.0, a 5% hydrogen fraction improved the cycle-by-cycle variations most significantly. While a larger hydrogen fraction is needed to achieve the excellent combustion characteristics under lean burn conditions, hydrogen direct injection can promote combustion process and is beneficial for enhancing stable combustion and reducing the cycle-by-cycle variations. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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21 pages, 6308 KiB  
Article
Research on Variable Parameter Drilling Method of Ti-CFRP-Ti Laminated Stacks Based on Real-Time Sensing of Drilling Axial Force
by Zhengzhu Zhang, Ning Zhang, Fenghe Wu, Weixiang Teng, Yingbing Sun and Baosu Guo
Sensors 2022, 22(3), 1188; https://doi.org/10.3390/s22031188 - 04 Feb 2022
Cited by 6 | Viewed by 2240
Abstract
Ti-CFRP-Ti laminated stacks have been widely used in aviation, aerospace, shipbuilding and other industries, owing to its excellent physical and electrochemical properties. However, chip blockages occur easily when drilling into Ti-CFRP-Ti laminated stacks, resulting in a rapid rise of drilling temperature and an [...] Read more.
Ti-CFRP-Ti laminated stacks have been widely used in aviation, aerospace, shipbuilding and other industries, owing to its excellent physical and electrochemical properties. However, chip blockages occur easily when drilling into Ti-CFRP-Ti laminated stacks, resulting in a rapid rise of drilling temperature and an increase of axial drilling force, which may lead to the intensification of tool wear and a decline of drilling quality. Cutting force signals can effectively reflect the drilling process and tool condition, however, the traditional plate dynamometer is typically difficult in realizing the follow-up online measurement. Therefore, an intelligent tool holder system for real-time sensing of the cutting force is developed and constructed in this paper, and the variable parameter drilling method of Ti-CFRP-Ti laminated stacks is studied on this basis. Firstly, an intelligent tool holder system with high flexibility and adaptability is designed; Secondly, a cutting force signal processing method based on compressed sensing (CS) theory is proposed to solve the problem of high-frequency signal transmission; Lastly, the drilling experiment of Ti-CFRP-Ti laminated stacks is carried out based on the intelligent tool holder system, and the drilling parameters are optimized using a compromise programming approach and analytic hierarchy process (AHP). The comparison of results show that the optimized drilling parameters can effectively reduce the hole wall surface roughness and improve the drilling efficiency while ensuring a small axial force. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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8 pages, 1798 KiB  
Communication
Rapid Detection of Three Common Bacteria Based on Fluorescence Spectroscopy
by Ranran Du, Dingtian Yang and Xiaoqing Yin
Sensors 2022, 22(3), 1168; https://doi.org/10.3390/s22031168 - 03 Feb 2022
Cited by 12 | Viewed by 3412
Abstract
As an important part of environmental water quality monitoring, efficient bacterial detection has attracted widespread attention. Among them, LIF (laser-induced fluorescence) technology has the characteristics of high efficiency and sensitivity for bacterial detection. To simplify the experimental process of bacterial detection, fluorescence emission [...] Read more.
As an important part of environmental water quality monitoring, efficient bacterial detection has attracted widespread attention. Among them, LIF (laser-induced fluorescence) technology has the characteristics of high efficiency and sensitivity for bacterial detection. To simplify the experimental process of bacterial detection, fluorescence emission spectra of E. coli (Escherichia coli) and its deactivated controls, K. pneumoniae (Klebsiella pneumoniae) and S. aureus (Staphylococcus aureus), were analyzed with fluorescence excitation by a 266 nm laser. By analyzing the results, it was found that the dominant fluorescence peaks of bacterial solutions at 335~350 nm were contributed by tryptophan, and the subfluorescence peaks at 515.9 nm were contributed by flavin; besides, K. pneumoniae and S. aureus had their own fluoresces characteristics, such as tyrosine contributing to sub-fluorescence peaks at 300 nm. The three species of bacteria can be differentiated with whole fluorescence spectrum by statistically analysis (p < 0.05), for various concentrations of aromatic amino acids and flavin in different bacteria. The experimental results also proved that the inactivation operation did not alter the spectral properties of E. coli. The indexes of fluorescence intensity and FIR (fluorescence intensity ratio, I335~350/I515.9) can be used to retrieve the bacteria concentration as well as for bacteria differentiation using the index of slopes. The detection limit of bacteria is less than ~105 cell/mL using laser induced fluorescence methods in the paper. The study demonstrated the rapid detection capability of the LIF bacterial detection system and its great potential for rapid quantitative analysis of bacteria. This may bring new insight into the detection of common bacteria in water in situ. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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21 pages, 4400 KiB  
Article
Vacuum Based Gas Sensing Material Characterization System for Precise and Simultaneous Measurement of Optical and Electrical Responses
by Jie Wei, Meng Zhao, Cong Wang, Jun Wang, Jian-Min Ye, Yu-Chen Wei, Zhe-Yi Li, Run Zhao, Guo-Zhen Liu, Yan-Hong Geng, Rui Wang, Hui-Dong Xiao, Ying Li, Chao-Ya Li, Zhi-Qiang Gao and Ju Gao
Sensors 2022, 22(3), 1014; https://doi.org/10.3390/s22031014 - 28 Jan 2022
Cited by 4 | Viewed by 2514
Abstract
Gas sensing performance characterization systems are essential for the research and development of gas sensing materials and devices. Although existing systems are almost completely automatically operated, the accuracies of gas concentration control and of pressure control and the ability to simultaneously detect different [...] Read more.
Gas sensing performance characterization systems are essential for the research and development of gas sensing materials and devices. Although existing systems are almost completely automatically operated, the accuracies of gas concentration control and of pressure control and the ability to simultaneously detect different sensor signals still require improvement. In this study, a high-precision gas sensing material characterization system is developed based on vacuum technology, with the objective of enabling the precise and simultaneous measurement of electrical responses. Because of the implementation of vacuum technology, the gas concentration control accuracy is improved more than 1600 times, whereas the pressure of the test ambient condition can be precisely adjusted between vacuum and 1.2 bar. The vacuum-assisted gas-exchanging mechanism also enables the sensor response time to be determined more accurately. The system is capable of performing sensitivity, selectivity, and stability tests and can control the ambient relative humidity in a precise manner. More importantly, the levels of performance of three different optical signal measurement set-ups were investigated and compared in terms of detection range, linearity, noise, and response time, based on which of their scopes of application were proposed. Finally, single-period and cyclical tests were performed to examine the ability of the system to detect optical and electrical responses simultaneously, both at a single wavelength and in a spectral region. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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17 pages, 2101 KiB  
Article
A Distributed Localization Method for Wireless Sensor Networks Based on Anchor Node Optimal Selection and Particle Filter
by Qinghua Luo, Chao Liu, Xiaozhen Yan, Yang Shao, Kexin Yang, Chenxu Wang and Zhiquan Zhou
Sensors 2022, 22(3), 1003; https://doi.org/10.3390/s22031003 - 27 Jan 2022
Cited by 11 | Viewed by 2690
Abstract
In wireless sensor networks, due to the significance of the location information of mobile nodes for many applications, location services are the basis of many application scenarios. However, node state and communication uncertainty affect the distance estimation and position calculation of the range-based [...] Read more.
In wireless sensor networks, due to the significance of the location information of mobile nodes for many applications, location services are the basis of many application scenarios. However, node state and communication uncertainty affect the distance estimation and position calculation of the range-based localization method, which makes it difficult to guarantee the localization accuracy and the system robustness of the distributed localization system. In this paper, we propose a distributed localization method based on anchor nodes selection and particle filter optimization. In this method, we first analyze the uncertainty of error propagation to the least-squares localization method. According to the proportional relation between localization error and uncertainty propagation, anchor nodes are selected optimally in real-time during the movement of mobile nodes. Then we use the ranging and position of the optimally selected anchor nodes to obtain the location information of the mobile nodes. Finally, the particle filter (PF) algorithm is utilized to gain the optimal estimation of the localization results. The experimental evaluation results verified that the proposed method effectively improves the localization accuracy and the robustness of the distributed system. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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15 pages, 4720 KiB  
Article
Development of a Smart Clinical Bluetooth Thermometer Based on an Improved Low-Power Resistive Transducer Circuit
by Sitong Sun, Jinglun Xv, Wilson Wang and Chengyuan Wang
Sensors 2022, 22(3), 874; https://doi.org/10.3390/s22030874 - 24 Jan 2022
Viewed by 2562
Abstract
Smart sensors have been used in many engineering monitoring and control applications. This work focuses on the development of a new type of clinical Bluetooth thermometer, based on an improved low-power resistive transducer circuit. Most existing resistive transducers use relatively complicated circuits with [...] Read more.
Smart sensors have been used in many engineering monitoring and control applications. This work focuses on the development of a new type of clinical Bluetooth thermometer, based on an improved low-power resistive transducer circuit. Most existing resistive transducers use relatively complicated circuits with higher cost and power consumption. To tackle these problems, especially in real applications, an improved low-power resistive transducer circuit is proposed in this work and is used to develop smart Bluetooth thermometers. The parameters of the resistive transducer circuit are selected by quantitative analysis and optimization to improve the performance of the low-power resistive transducer circuit. The effectiveness of the proposed design technology was verified by tests. The temperature measurement error of the new smart Bluetooth thermometer is less than 0.1 °C, which can not only meet the clinical use requirements but also has lower cost and power consumption. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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17 pages, 5237 KiB  
Article
E-TBNet: Light Deep Neural Network for Automatic Detection of Tuberculosis with X-ray DR Imaging
by Le An, Kexin Peng, Xing Yang, Pan Huang, Yan Luo, Peng Feng and Biao Wei
Sensors 2022, 22(3), 821; https://doi.org/10.3390/s22030821 - 21 Jan 2022
Cited by 17 | Viewed by 2724
Abstract
Currently, the tuberculosis (TB) detection model based on chest X-ray images has the problem of excessive reliance on hardware computing resources, high equipment performance requirements, and being harder to deploy in low-cost personal computer and embedded devices. An efficient tuberculosis detection model is [...] Read more.
Currently, the tuberculosis (TB) detection model based on chest X-ray images has the problem of excessive reliance on hardware computing resources, high equipment performance requirements, and being harder to deploy in low-cost personal computer and embedded devices. An efficient tuberculosis detection model is proposed to achieve accurate, efficient, and stable tuberculosis screening on devices with lower hardware levels. Due to the particularity of the chest X-ray images of TB patients, there are fewer labeled data, and the deep neural network model is difficult to fully train. We first analyzed the data distribution characteristics of two public TB datasets, and found that the two-stage tuberculosis identification (first divide, then classify) is insufficient. Secondly, according to the particularity of the detection image(s), the basic residual module was optimized and improved, and this is regarded as a crucial component of this article’s network. Finally, an efficient attention mechanism was introduced, which was used to fuse the channel features. The network architecture was optimally designed and adjusted according to the correct and sufficient experimental content. In order to evaluate the performance of the network, it was compared with other lightweight networks under personal computer and Jetson Xavier embedded devices. The experimental results show that the recall rate and accuracy of the E-TBNet proposed in this paper are better than those of classic lightweight networks such as SqueezeNet and ShuffleNet, and it also has a shorter reasoning time. E-TBNet will be more advantageous to deploy on equipment with low levels of hardware. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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21 pages, 10779 KiB  
Article
Design and Analysis of a 2-DOF Electromagnetic Actuator with an Improved Halbach Array for the Magnetic Suspension Platform
by Fei Yang, Yong Zhao, Huaiyu Li, Xingke Mu, Wenqiao Zhang, Honghao Yue and Rongqiang Liu
Sensors 2022, 22(3), 790; https://doi.org/10.3390/s22030790 - 20 Jan 2022
Cited by 6 | Viewed by 2151
Abstract
For large bearing capacity and low current consumption of the magnetic suspension platform, a 2-DOF electromagnetic actuator with a new structure of halbach array is proposed to improve driving force coefficients. The structure and the working principle are introduced. An accurate sub domain [...] Read more.
For large bearing capacity and low current consumption of the magnetic suspension platform, a 2-DOF electromagnetic actuator with a new structure of halbach array is proposed to improve driving force coefficients. The structure and the working principle are introduced. An accurate sub domain model of the new structure is established to accurately and rapidly calculate the magnetic field distribution for obtaining the parameters and performance of the electromagnetic actuators. The analytical model results are verified by the finite element method. The force/torque model of the magnetic suspension platform is established based on the proposed 2-DOF electromagnetic actuator. Three position-sensitive detectors and six accelerometers are applied to perceive in real time the posture and vibration acceleration of the platform, respectively. Their hardware information is introduced and measurement models are established based on the layout. Finally, the electromagnetic characteristics of the proposed actuator are investigated and compared with the conventional counterpart by finite element analysis. The results show that the average magnetic field, 0.432 T, horizontal and vertical force coefficient, 92.3 N/A and 30.95 N/A, and torque in x and z direction, 3.61 N·m and 8.49 N·m, of the proposed actuator are larger than those of the conventional one. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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18 pages, 8366 KiB  
Article
A Docking Mechanism Based on a Stewart Platform and Its Tracking Control Based on Information Fusion Algorithm
by Gan Zhan, Shaohua Niu, Wencai Zhang, Xiaoyan Zhou, Jinhui Pang, Yingchao Li and Jigang Zhan
Sensors 2022, 22(3), 770; https://doi.org/10.3390/s22030770 - 20 Jan 2022
Cited by 6 | Viewed by 3049
Abstract
Aiming at the problem of unmanned reconfiguration and docking of ground vehicles under complex working conditions, we designed a piece of docking equipment composed of an active mechanism based on a six-degree-of-freedom platform and a locking mechanism with multi-sensors. Through the proposed control [...] Read more.
Aiming at the problem of unmanned reconfiguration and docking of ground vehicles under complex working conditions, we designed a piece of docking equipment composed of an active mechanism based on a six-degree-of-freedom platform and a locking mechanism with multi-sensors. Through the proposed control method based on laser and image sensor information fusion calculation, the six-dimensional posture information of the mechanism during the docking process is captured in real time so as to achieve high-precision docking. Finally, the effectiveness of the method and the feasibility of the 6-DOF platform are verified by the established model. The results show that the mechanism can meet the requirements of smooth docking of ground unmanned vehicles. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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13 pages, 11922 KiB  
Communication
Multi-Angle Optical Image Automatic Registration by Combining Point and Line Features
by Jia Su, Juntong Meng, Weimin Hou, Rong Wang and Xin Luo
Sensors 2022, 22(3), 739; https://doi.org/10.3390/s22030739 - 19 Jan 2022
Cited by 5 | Viewed by 1723
Abstract
Image registration is an important basis of image processing, which is of great significance in image mosaicking, target recognition, and change detection. Aiming at the automatic registration problem of multi-angle optical images for ground scenes, a registration method combining point features and line [...] Read more.
Image registration is an important basis of image processing, which is of great significance in image mosaicking, target recognition, and change detection. Aiming at the automatic registration problem of multi-angle optical images for ground scenes, a registration method combining point features and line features to register images is proposed. Firstly, the LSD (Line Segment Detector) algorithm is used to extract line features of images. The obtained line segments whose length are less than a given threshold are eliminated by a visual significant algorithm. Then, an affine transform model obtained by estimating a Gaussian mixture model (GMM) is applied to the image to be matched. Lastly, Harris point features are utilized in fine matching to overcome shortages of methods based on line features. In experiments, the proposed algorithm is compared with popular feature-based registration algorithms. The results indicate that the proposed algorithm in this work has obvious advantages in terms of registration accuracy and reliability for optical images acquired at different angles. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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20 pages, 90142 KiB  
Article
Green Citrus Detection and Counting in Orchards Based on YOLOv5-CS and AI Edge System
by Shilei Lyu, Ruiyao Li, Yawen Zhao, Zhen Li, Renjie Fan and Siying Liu
Sensors 2022, 22(2), 576; https://doi.org/10.3390/s22020576 - 12 Jan 2022
Cited by 39 | Viewed by 5462
Abstract
Green citrus detection in citrus orchards provides reliable support for production management chains, such as fruit thinning, sunburn prevention and yield estimation. In this paper, we proposed a lightweight object detection YOLOv5-CS (Citrus Sort) model to realize object detection and the accurate counting [...] Read more.
Green citrus detection in citrus orchards provides reliable support for production management chains, such as fruit thinning, sunburn prevention and yield estimation. In this paper, we proposed a lightweight object detection YOLOv5-CS (Citrus Sort) model to realize object detection and the accurate counting of green citrus in the natural environment. First, we employ image rotation codes to improve the generalization ability of the model. Second, in the backbone, a convolutional layer is replaced by a convolutional block attention module, and a detection layer is embedded to improve the detection accuracy of the little citrus. Third, both the loss function CIoU (Complete Intersection over Union) and cosine annealing algorithm are used to get the better training effect of the model. Finally, our model is migrated and deployed to the AI (Artificial Intelligence) edge system. Furthermore, we apply the scene segmentation method using the “virtual region” to achieve accurate counting of the green citrus, thereby forming an embedded system of green citrus counting by edge computing. The results show that the mAP@.5 of the YOLOv5-CS model for green citrus was 98.23%, and the recall is 97.66%. The inference speed of YOLOv5-CS detecting a picture on the server is 0.017 s, and the inference speed on Nvidia Jetson Xavier NX is 0.037 s. The detection and counting frame rate of the AI edge system-side counting system is 28 FPS, which meets the counting requirements of green citrus. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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18 pages, 3379 KiB  
Article
Vibration Separation Methodology Compensated by Time-Varying Transfer Function for Fault Diagnosis of Non-Hunting Tooth Planetary Gearbox
by Shuiguang Tong, Junjie Li, Feiyun Cong, Zilong Fu and Zheming Tong
Sensors 2022, 22(2), 557; https://doi.org/10.3390/s22020557 - 12 Jan 2022
Cited by 8 | Viewed by 2424
Abstract
Due to planetary movement of planet gears, the vibration signal perceived by a stationary sensor is modulated and difficult to diagnose. This paper proposed a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS), which is a further development of the vibration [...] Read more.
Due to planetary movement of planet gears, the vibration signal perceived by a stationary sensor is modulated and difficult to diagnose. This paper proposed a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS), which is a further development of the vibration separation (VS) method in the diagnosis of non-hunting tooth planetary gearboxes. On the basis of VS, multi-teeth VS is proposed to extract and synthesize the meshing signal of a planet gear using a single transducer. Considering the movement regularity of a planetary gearbox, the time-varying transfer function (TVTF) is represented by a generalized expression. The TVTF is constructed using a segment of healthy signal and an evaluation indicator is established to optimize the parameters of the TVTF. The constructed TVTF is applied to overcome the amplitude modulation effect and highlight fault characteristics. After that, experiments with baseline, pitting, and compound localized faults planet gears were conducted on a non-hunting tooth planetary gearbox test rig, respectively. The results demonstrate that incipient failure on a planet gear can be detected effectively, and relative location of the local faults can be determined accurately. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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14 pages, 4383 KiB  
Article
A Laser-Based Multipass Absorption Sensor for Sub-ppm Detection of Methane, Acetylene and Ammonia
by Wei Duan, Fuwu Yan, Yu Wang, Hui Zhang, Liuhao Ma, Daxin Wen, Wei Wang, Gang Sheng and Qiang Wang
Sensors 2022, 22(2), 556; https://doi.org/10.3390/s22020556 - 12 Jan 2022
Cited by 9 | Viewed by 3045
Abstract
A compact, sensitive laser-based absorption sensor for multispecies monitoring of methane (CH4), acetylene (C2H2) and ammonia (NH3) was developed using a compact multipass gas cell. The gas cell is 8.8 cm long and has an [...] Read more.
A compact, sensitive laser-based absorption sensor for multispecies monitoring of methane (CH4), acetylene (C2H2) and ammonia (NH3) was developed using a compact multipass gas cell. The gas cell is 8.8 cm long and has an effective optical path length of 3.0 m with a sampling volume of 75 mL. The sensor is composed of three fiber-coupled distributed feedback lasers operating near 1512 nm, 1532 nm and 1654 nm, an InGaAs photodetector and a custom-designed software for data acquisition, signal processing and display. The lasers were scanned over the target absorption features at 1 Hz. First-harmonic-normalized wavelength modulation spectroscopy (f = 3 kHz) with the second harmonic detection (WMS-2f/1f) is employed to eliminate the unwanted power fluctuations of the transmitted laser caused by aerosol/particles scattering, absorption and beam-steering. The multispecies sensor has excellent linear responses (R2 > 0.997) within the gas concentration range of 1–1000 ppm and shows a detection limit of 0.32 ppm for CH4, 0.16 ppm for C2H2 and 0.23 ppm for NH3 at 1 s response time. The Allan–Werle deviation analysis verifies the long-term stability of the sensor, indicating a minimal detection limit of 20–34 ppb were achieved after 60–148 s integration time. Flow test of the portable multispecies sensor is also demonstrated in this work. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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10 pages, 2522 KiB  
Communication
Effects of Optical Beams on MIMO Visible Light Communication Channel Characteristics
by Jupeng Ding, Chih-Lin I, Jintao Wang and Hui Yang
Sensors 2022, 22(1), 216; https://doi.org/10.3390/s22010216 - 29 Dec 2021
Cited by 2 | Viewed by 1674
Abstract
Under 5G envision, for pushing visible light communication (VLC) channel model evolution to various non-Lambertian beams, this paper introduces the typical commercial non-Lambertian beams, such as Luxeon rebel and side emitter, into the conventional analytical VLC channel model. The numerical results illustrate that [...] Read more.
Under 5G envision, for pushing visible light communication (VLC) channel model evolution to various non-Lambertian beams, this paper introduces the typical commercial non-Lambertian beams, such as Luxeon rebel and side emitter, into the conventional analytical VLC channel model. The numerical results illustrate that the non-Lambertian beams can significantly affect the VLC channel frequency response characteristics. Compared with the traditional Lambertian beam, Side Emitter optical beam could naturally bring up to about 56.8% VLC multi input multi output channel capacity deviation, which objectively opens a new discussion dimension for enhancing VLC transmission performance. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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14 pages, 8105 KiB  
Article
Design of Citrus Fruit Detection System Based on Mobile Platform and Edge Computer Device
by Heqing Huang, Tongbin Huang, Zhen Li, Shilei Lyu and Tao Hong
Sensors 2022, 22(1), 59; https://doi.org/10.3390/s22010059 - 23 Dec 2021
Cited by 16 | Viewed by 2937
Abstract
Citrus fruit detection can provide technical support for fine management and yield determination of citrus orchards. Accurate detection of citrus fruits in mountain orchards is challenging because of leaf occlusion and citrus fruit mutual occlusion of different fruits. This paper presents a citrus [...] Read more.
Citrus fruit detection can provide technical support for fine management and yield determination of citrus orchards. Accurate detection of citrus fruits in mountain orchards is challenging because of leaf occlusion and citrus fruit mutual occlusion of different fruits. This paper presents a citrus detection task that combines UAV data collection, AI embedded device, and target detection algorithm. The system used a small unmanned aerial vehicle equipped with a camera to take full-scale pictures of citrus trees; at the same time, we extended the state-of-the-art model target detection algorithm, added the attention mechanism and adaptive fusion feature method, improved the model’s performance; to facilitate the deployment of the model, we used the pruning method to reduce the amount of model calculation and parameters. The improved target detection algorithm is ported to the edge computing end to detect the data collected by the unmanned aerial vehicle. The experiment was performed on the self-made citrus dataset, the detection accuracy was 93.32%, and the processing speed at the edge computing device was 180 ms/frame. This method is suitable for citrus detection tasks in the mountainous orchard environment, and it can help fruit growers to estimate their yield. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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15 pages, 2705 KiB  
Article
Relative Pose Determination of Uncooperative Spacecraft Based on Circle Feature
by Yue Liu, Shijie Zhang and Xiangtian Zhao
Sensors 2021, 21(24), 8495; https://doi.org/10.3390/s21248495 - 20 Dec 2021
Cited by 3 | Viewed by 2437
Abstract
This paper investigates the problem of spacecraft relative navigation with respect to an unknown target during the close-proximity operations in the on-orbit service system. The serving spacecraft is equipped with a Time-of-Flight (ToF) camera for object recognition and feature detection. A fast and [...] Read more.
This paper investigates the problem of spacecraft relative navigation with respect to an unknown target during the close-proximity operations in the on-orbit service system. The serving spacecraft is equipped with a Time-of-Flight (ToF) camera for object recognition and feature detection. A fast and robust relative navigation strategy for acquisition is presented without any extra information about the target by using the natural circle features. The architecture of the proposed relative navigation strategy consists of three ingredients. First, a point cloud segmentation method based on the auxiliary gray image is developed for fast extraction of the circle feature point cloud of the target. Secondly, a new parameter fitting method of circle features is proposed including circle feature calculation by two different geometric models and results’ fusion. Finally, a specific definition of the coordinate frame system is introduced to solve the relative pose with respect to the uncooperative target. In order to validate the efficiency of the segmentation, an experimental test is conducted based on real-time image data acquired by the ToF camera. The total time consumption is saved by 94%. In addition, numerical simulations are carried out to evaluate the proposed navigation algorithm. It shows good robustness under the different levels of noises. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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19 pages, 7377 KiB  
Article
Hybrid Deflection of Spoiler Influencing Radar Cross-Section of Tailless Fighter
by Zeyang Zhou and Jun Huang
Sensors 2021, 21(24), 8459; https://doi.org/10.3390/s21248459 - 18 Dec 2021
Cited by 2 | Viewed by 2946
Abstract
With the continuous development of advanced fighters towards tailless and flying wing layouts, diverse control surfaces have become the mainstream design. To study the influence of spoiler control surface on the radar cross-section (RCS) of a tailless fighter, a calculation method is presented. [...] Read more.
With the continuous development of advanced fighters towards tailless and flying wing layouts, diverse control surfaces have become the mainstream design. To study the influence of spoiler control surface on the radar cross-section (RCS) of a tailless fighter, a calculation method is presented. The deflection angle of the spoiler is controlled by the fixed mode, linear mode, and smooth mode. The results show that the opening action of the spoiler will break the original stealth characteristics of the aircraft at the key azimuth angles of the head and tail. As the elevation angle increases, this adverse effect will spread to the side. The influence of the different dynamic deflection modes of the spoiler on the aircraft RCS is analyzed. Compared with the linear dynamic deflection mode, the smooth dynamic deflection mode is conducive to the reduction in the average RCS at the given head azimuth. The presented method is effective to study the influence of the spoiler deflection on the electromagnetic scattering characteristics of the tailless aircraft. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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19 pages, 7099 KiB  
Article
Combining Regional Energy and Intuitionistic Fuzzy Sets for Infrared and Visible Image Fusion
by Xiaoxue Xing, Cong Luo, Jian Zhou, Minghan Yan, Cheng Liu and Tingfa Xu
Sensors 2021, 21(23), 7813; https://doi.org/10.3390/s21237813 - 24 Nov 2021
Cited by 2 | Viewed by 1693
Abstract
To get more obvious target information and more texture features, a new fusion method for the infrared (IR) and visible (VIS) images combining regional energy (RE) and intuitionistic fuzzy sets (IFS) is proposed, and this method can be described by several steps as [...] Read more.
To get more obvious target information and more texture features, a new fusion method for the infrared (IR) and visible (VIS) images combining regional energy (RE) and intuitionistic fuzzy sets (IFS) is proposed, and this method can be described by several steps as follows. Firstly, the IR and VIS images are decomposed into low- and high-frequency sub-bands by non-subsampled shearlet transform (NSST). Secondly, RE-based fusion rule is used to obtain the low-frequency pre-fusion image, which allows the important target information preserved in the resulting image. Based on the pre-fusion image, the IFS-based fusion rule is introduced to achieve the final low-frequency image, which enables more important texture information transferred to the resulting image. Thirdly, the ‘max-absolute’ fusion rule is adopted to fuse high-frequency sub-bands. Finally, the fused image is reconstructed by inverse NSST. The TNO and RoadScene datasets are used to evaluate the proposed method. The simulation results demonstrate that the fused images of the proposed method have more obvious targets, higher contrast, more plentiful detailed information, and local features. Qualitative and quantitative analysis results show that the presented method is superior to the other nine advanced fusion methods. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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Review

Jump to: Research

31 pages, 61211 KiB  
Review
Force-Sensitive Interface Engineering in Flexible Pressure Sensors: A Review
by Guojun Tai, Dapeng Wei, Min Su, Pei Li, Lei Xie and Jun Yang
Sensors 2022, 22(7), 2652; https://doi.org/10.3390/s22072652 - 30 Mar 2022
Cited by 17 | Viewed by 4115
Abstract
Flexible pressure sensors have received extensive attention in recent years due to their great importance in intelligent electronic devices. In order to improve the sensing performance of flexible pressure sensors, researchers are committed to making improvements in device materials, force-sensitive interfaces, and device [...] Read more.
Flexible pressure sensors have received extensive attention in recent years due to their great importance in intelligent electronic devices. In order to improve the sensing performance of flexible pressure sensors, researchers are committed to making improvements in device materials, force-sensitive interfaces, and device structures. This paper focuses on the force-sensitive interface engineering of the device, which listing the main preparation methods of various force-sensitive interface microstructures and describing their respective advantages and disadvantages from the working mechanisms and practical applications of the flexible pressure sensor. What is more, the device structures of the flexible pressure sensor are investigated with the regular and irregular force-sensitive interface and accordingly the influences of different device structures on the performance are discussed. Finally, we not only summarize diverse practical applications of the existing flexible pressure sensors controlled by the force-sensitive interface but also briefly discuss some existing problems and future prospects of how to improve the device performance through the adjustment of the force-sensitive interface. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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20 pages, 48508 KiB  
Review
Intensity-Modulated Polymer Optical Fiber-Based Refractive Index Sensor: A Review
by Chuanxin Teng, Rui Min, Jie Zheng, Shijie Deng, Maosen Li, Li Hou and Libo Yuan
Sensors 2022, 22(1), 81; https://doi.org/10.3390/s22010081 - 23 Dec 2021
Cited by 25 | Viewed by 4920
Abstract
The simple and highly sensitive measurement of the refractive index (RI) of liquids is critical for designing the optical instruments and important in biochemical sensing applications. Intensity modulation-based polymer optical fiber (POF) RI sensors have a lot of advantages including low cost, easy [...] Read more.
The simple and highly sensitive measurement of the refractive index (RI) of liquids is critical for designing the optical instruments and important in biochemical sensing applications. Intensity modulation-based polymer optical fiber (POF) RI sensors have a lot of advantages including low cost, easy fabrication and operation, good flexibility, and working in the visible wavelength. In this review, recent developments of the intensity modulation POF-based RI sensors are summarized. The materials of the POF and the working principle of intensity modulation are introduced briefly. Moreover, the RI sensing performance of POF sensors with different structures including tapered, bent, and side-polished structures, among others, are presented in detail. Finally, the sensing performance for different structures of POF-based RI sensors are compared and discussed. Full article
(This article belongs to the Special Issue Instrument and Measurement Based on Sensing Technology in China)
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