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Sensors, Volume 15, Issue 7 (July 2015) , Pages 14830-17826

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Open AccessArticle
Real-Time PPP Based on the Coupling Estimation of Clock Bias and Orbit Error with Broadcast Ephemeris
Sensors 2015, 15(7), 17808-17826; https://doi.org/10.3390/s150717808
Received: 20 May 2015 / Revised: 27 June 2015 / Accepted: 10 July 2015 / Published: 22 July 2015
Cited by 6 | Viewed by 2227 | PDF Full-text (1503 KB) | HTML Full-text | XML Full-text
Abstract
Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service [...] Read more.
Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service will be the dominant mode in the future. IGS is providing such an operational service (RTS) and there are also commercial systems like Trimble RTX in operation. On the basis of the regional Continuous Operational Reference System (CORS), a real-time PPP algorithm is proposed to apply the coupling estimation of clock bias and orbit error. The projection of orbit error onto the satellite-receiver range has the same effects on positioning accuracy with clock bias. Therefore, in satellite clock estimation, part of the orbit error can be absorbed by the clock bias and the effects of residual orbit error on positioning accuracy can be weakened by the evenly distributed satellite geometry. In consideration of the simple structure of pseudorange equations and the high precision of carrier-phase equations, the clock bias estimation method coupled with orbit error is also improved. Rovers obtain PPP results by receiving broadcast ephemeris and real-time satellite clock bias coupled with orbit error. By applying the proposed algorithm, the precise orbit products provided by GNSS analysis centers are rendered no longer necessary. On the basis of previous theoretical analysis, a real-time PPP system was developed. Some experiments were then designed to verify this algorithm. Experimental results show that the newly proposed approach performs better than the traditional PPP based on International GNSS Service (IGS) real-time products. The positioning accuracies of the rovers inside and outside the network are improved by 38.8% and 36.1%, respectively. The PPP convergence speeds are improved by up to 61.4% and 65.9%. The new approach can change the traditional PPP mode because of its advantages of independence, high positioning precision, and real-time performance. It could be an alternative solution for regional positioning service before global PPP service comes into operation. Full article
(This article belongs to the Section Remote Sensors, Control, and Telemetry)
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Open AccessArticle
Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology
Sensors 2015, 15(7), 17786-17807; https://doi.org/10.3390/s150717786
Received: 25 May 2015 / Revised: 11 July 2015 / Accepted: 16 July 2015 / Published: 22 July 2015
Cited by 2 | Viewed by 2633 | PDF Full-text (1670 KB) | HTML Full-text | XML Full-text
Abstract
This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP [...] Read more.
This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. Full article
(This article belongs to the Special Issue Silicon Based Optical Sensors)
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Open AccessArticle
Discrimination of Rice with Different Pretreatment Methods by Using a Voltammetric Electronic Tongue
Sensors 2015, 15(7), 17767-17785; https://doi.org/10.3390/s150717767
Received: 25 May 2015 / Revised: 9 July 2015 / Accepted: 17 July 2015 / Published: 22 July 2015
Cited by 5 | Viewed by 1826 | PDF Full-text (1252 KB) | HTML Full-text | XML Full-text
Abstract
In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice [...] Read more.
In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice samples. To this aim, a voltammetric array of sensors based on metallic electrodes was used as the sensing part. The different samples were analyzed by cyclic voltammetry with two sample-pretreatment methods. Discriminant Factorial Analysis was used to visualize the different categories of rice samples; however, radial basis function (RBF) artificial neural network with leave-one-out cross-validation method was employed for prediction modeling. The collected signal data were first compressed employing fast Fourier transform (FFT) and then significant features were extracted from the voltammetric signals. The experimental results indicated that the sample solutions obtained by the non-crushed pretreatment method could efficiently meet the effect of discrimination and recognition. The satisfactory prediction results of voltammetric electronic tongue based on RBF artificial neural network were obtained with less than five-fold dilution of the sample solution. The main objective of this study was to develop primary research on the application of an electronic tongue system for the discrimination and prediction of solid foods and provide an objective assessment tool for the food industry. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor
Sensors 2015, 15(7), 17748-17766; https://doi.org/10.3390/s150717748
Received: 21 May 2015 / Revised: 21 May 2015 / Accepted: 17 July 2015 / Published: 21 July 2015
Cited by 3 | Viewed by 2249 | PDF Full-text (1207 KB) | HTML Full-text | XML Full-text
Abstract
Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true [...] Read more.
Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites
Sensors 2015, 15(7), 17728-17747; https://doi.org/10.3390/s150717728
Received: 2 June 2015 / Revised: 2 June 2015 / Accepted: 16 July 2015 / Published: 21 July 2015
Cited by 25 | Viewed by 2801 | PDF Full-text (6797 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a [...] Read more.
This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT) onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity. Full article
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Open AccessArticle
Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media
Sensors 2015, 15(7), 17715-17727; https://doi.org/10.3390/s150717715
Received: 30 April 2015 / Revised: 27 June 2015 / Accepted: 9 July 2015 / Published: 21 July 2015
Cited by 8 | Viewed by 2332 | PDF Full-text (2718 KB) | HTML Full-text | XML Full-text
Abstract
With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance [...] Read more.
With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3 in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications. Full article
(This article belongs to the Special Issue Sensors and Smart Cities)
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Open AccessArticle
Fast T Wave Detection Calibrated by Clinical Knowledge with Annotation of P and T Waves
Sensors 2015, 15(7), 17693-17714; https://doi.org/10.3390/s150717693
Received: 1 June 2015 / Revised: 8 July 2015 / Accepted: 10 July 2015 / Published: 21 July 2015
Cited by 13 | Viewed by 2374 | PDF Full-text (1460 KB) | HTML Full-text | XML Full-text
Abstract
Background: There are limited studies on the automatic detection of T waves in arrhythmic electrocardiogram (ECG) signals. This is perhaps because there is no available arrhythmia dataset with annotated T waves. There is a growing need to develop numerically-efficient algorithms that can accommodate [...] Read more.
Background: There are limited studies on the automatic detection of T waves in arrhythmic electrocardiogram (ECG) signals. This is perhaps because there is no available arrhythmia dataset with annotated T waves. There is a growing need to develop numerically-efficient algorithms that can accommodate the new trend of battery-driven ECG devices. Moreover, there is also a need to analyze long-term recorded signals in a reliable and time-efficient manner, therefore improving the diagnostic ability of mobile devices and point-of-care technologies. Methods: Here, the T wave annotation of the well-known MIT-BIH arrhythmia database is discussed and provided. Moreover, a simple fast method for detecting T waves is introduced. A typical T wave detection method has been reduced to a basic approach consisting of two moving averages and dynamic thresholds. The dynamic thresholds were calibrated using four clinically known types of sinus node response to atrial premature depolarization (compensation, reset, interpolation, and reentry). Results: The determination of T wave peaks is performed and the proposed algorithm is evaluated on two well-known databases, the QT and MIT-BIH Arrhythmia databases. The detector obtained a sensitivity of 97.14% and a positive predictivity of 99.29% over the first lead of the validation databases (total of 221,186 beats). Conclusions: We present a simple yet very reliable T wave detection algorithm that can be potentially implemented on mobile battery-driven devices. In contrast to complex methods, it can be easily implemented in a digital filter design. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle
Multiscale Trend Analysis for Pampa Grasslands Using Ground Data and Vegetation Sensor Imagery
Sensors 2015, 15(7), 17666-17692; https://doi.org/10.3390/s150717666
Received: 14 April 2015 / Revised: 30 June 2015 / Accepted: 9 July 2015 / Published: 21 July 2015
Cited by 4 | Viewed by 2190 | PDF Full-text (3957 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study aimed to evaluate changes in the aboveground net primary productivity (ANPP) of grasslands in the Pampa biome by using experimental plots and changes in the spectral responses of similar vegetation communities obtained by remote sensing and to compare both datasets with [...] Read more.
This study aimed to evaluate changes in the aboveground net primary productivity (ANPP) of grasslands in the Pampa biome by using experimental plots and changes in the spectral responses of similar vegetation communities obtained by remote sensing and to compare both datasets with meteorological variations to validate the transition scales of the datasets. Two different geographic scales were considered in this study. At the local scale, an analysis of the climate and its direct influences on grassland ANPP was performed using data from a long-term experiment. At the regional scale, the influences of climate on the grassland reflectance patterns were determined using vegetation sensor imagery data. Overall, the monthly variations of vegetation canopy growth analysed using environmental changes (air temperature, total rainfall and total evapotranspiration) were similar. The results from the ANPP data and the NDVI data showed the that variations in grassland growth were similar and independent of the analysis scale, which indicated that local data and the relationships of local data with climate can be considered at the regional scale in the Pampa biome by using remote sensing. Full article
(This article belongs to the Section Remote Sensors, Control, and Telemetry)
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Open AccessReview
Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection
Sensors 2015, 15(7), 17649-17665; https://doi.org/10.3390/s150717649
Received: 8 April 2015 / Revised: 30 June 2015 / Accepted: 14 July 2015 / Published: 20 July 2015
Cited by 24 | Viewed by 3403 | PDF Full-text (3300 KB) | HTML Full-text | XML Full-text
Abstract
Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can [...] Read more.
Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can lay the foundations for future generation diagnostics by providing means to detect biomarkers in a highly sensitive, specific, quantitative and multiplexed fashion. Here, we review an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS), and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection. We discuss two distinct modalities for IRIS: (i) low-magnification (ensemble biomolecular mass measurements) and (ii) high-magnification (digital detection of individual nanoparticles) along with their applications, including label-free detection of multiplexed protein chips, measurement of single nucleotide polymorphism, quantification of transcription factor DNA binding, and high sensitivity digital sensing and characterization of nanoparticles and viruses. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
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Open AccessArticle
Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks
Sensors 2015, 15(7), 17621-17648; https://doi.org/10.3390/s150717621
Received: 3 June 2015 / Revised: 12 July 2015 / Accepted: 14 July 2015 / Published: 20 July 2015
Cited by 3 | Viewed by 2019 | PDF Full-text (476 KB) | HTML Full-text | XML Full-text
Abstract
Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering [...] Read more.
Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. Full article
(This article belongs to the Section Sensor Networks)
Open AccessReview
Wireless Sensor Network Optimization: Multi-Objective Paradigm
Sensors 2015, 15(7), 17572-17620; https://doi.org/10.3390/s150717572
Received: 2 June 2015 / Revised: 1 July 2015 / Accepted: 6 July 2015 / Published: 20 July 2015
Cited by 37 | Viewed by 3375 | PDF Full-text (3638 KB) | HTML Full-text | XML Full-text
Abstract
Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may [...] Read more.
Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may or may not conflict with each other. Keeping in view the nature of the application, the sensing scenario and input/output of the problem, the type of optimization problem changes. To address different nature of optimization problems relating to wireless sensor network design, deployment, operation, planing and placement, there exist a plethora of optimization solution types. We review and analyze different desirable objectives to show whether they conflict with each other, support each other or they are design dependent. We also present a generic multi-objective optimization problem relating to wireless sensor network which consists of input variables, required output, objectives and constraints. A list of constraints is also presented to give an overview of different constraints which are considered while formulating the optimization problems in wireless sensor networks. Keeping in view the multi facet coverage of this article relating to multi-objective optimization, this will open up new avenues of research in the area of multi-objective optimization relating to wireless sensor networks. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle
Potentiometric NO2 Sensors Based on Thin Stabilized Zirconia Electrolytes and Asymmetric (La0.8Sr0.2)0.95MnO3 Electrodes
Sensors 2015, 15(7), 17558-17571; https://doi.org/10.3390/s150717558
Received: 4 June 2015 / Revised: 1 July 2015 / Accepted: 6 July 2015 / Published: 20 July 2015
Cited by 3 | Viewed by 2599 | PDF Full-text (3464 KB) | HTML Full-text | XML Full-text
Abstract
Here we report on a new architecture for potentiometric NO2 sensors that features thin 8YSZ electrolytes sandwiched between two porous (La0.8Sr0.2)0.95MnO3 (LSM95) layers—one thick and the other thin—fabricated by the tape casting and co-firing techniques. [...] Read more.
Here we report on a new architecture for potentiometric NO2 sensors that features thin 8YSZ electrolytes sandwiched between two porous (La0.8Sr0.2)0.95MnO3 (LSM95) layers—one thick and the other thin—fabricated by the tape casting and co-firing techniques. Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages. In the meanwhile, thin LSM95 layers perform better than Pt as the sensing electrode since the former can provide higher response voltages and better linear relationship between the sensitivities and the NO2 concentrations over 40–1000 ppm. The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C. Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages. Full article
(This article belongs to the Special Issue Gas Sensors—Designs and Applications)
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Open AccessArticle
Collaborative WiFi Fingerprinting Using Sensor-Based Navigation on Smartphones
Sensors 2015, 15(7), 17534-17557; https://doi.org/10.3390/s150717534
Received: 3 June 2015 / Revised: 4 July 2015 / Accepted: 10 July 2015 / Published: 20 July 2015
Cited by 14 | Viewed by 2678 | PDF Full-text (4871 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a method that trains the WiFi fingerprint database using sensor-based navigation solutions. Since micro-electromechanical systems (MEMS) sensors provide only a short-term accuracy but suffer from the accuracy degradation with time, we restrict the time length of available indoor navigation trajectories, [...] Read more.
This paper presents a method that trains the WiFi fingerprint database using sensor-based navigation solutions. Since micro-electromechanical systems (MEMS) sensors provide only a short-term accuracy but suffer from the accuracy degradation with time, we restrict the time length of available indoor navigation trajectories, and conduct post-processing to improve the sensor-based navigation solution. Different middle-term navigation trajectories that move in and out of an indoor area are combined to make up the database. Furthermore, we evaluate the effect of WiFi database shifts on WiFi fingerprinting using the database generated by the proposed method. Results show that the fingerprinting errors will not increase linearly according to database (DB) errors in smartphone-based WiFi fingerprinting applications. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Evaluation of Fear Using Nonintrusive Measurement of Multimodal Sensors
Sensors 2015, 15(7), 17507-17533; https://doi.org/10.3390/s150717507
Received: 12 April 2015 / Revised: 13 July 2015 / Accepted: 15 July 2015 / Published: 20 July 2015
Cited by 11 | Viewed by 2365 | PDF Full-text (4855 KB) | HTML Full-text | XML Full-text
Abstract
Most previous research into emotion recognition used either a single modality or multiple modalities of physiological signal. However, the former method allows for limited enhancement of accuracy, and the latter has the disadvantages that its performance can be affected by head or body [...] Read more.
Most previous research into emotion recognition used either a single modality or multiple modalities of physiological signal. However, the former method allows for limited enhancement of accuracy, and the latter has the disadvantages that its performance can be affected by head or body movements. Further, the latter causes inconvenience to the user due to the sensors attached to the body. Among various emotions, the accurate evaluation of fear is crucial in many applications, such as criminal psychology, intelligent surveillance systems and the objective evaluation of horror movies. Therefore, we propose a new method for evaluating fear based on nonintrusive measurements obtained using multiple sensors. Experimental results based on the t-test, the effect size and the sum of all of the correlation values with other modalities showed that facial temperature and subjective evaluation are more reliable than electroencephalogram (EEG) and eye blinking rate for the evaluation of fear. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Low Power Resistive Oxygen Sensor Based on Sonochemical SrTi0.6Fe0.4O2.8 (STFO40)
Sensors 2015, 15(7), 17495-17506; https://doi.org/10.3390/s150717495
Received: 16 June 2015 / Revised: 24 June 2015 / Accepted: 29 June 2015 / Published: 20 July 2015
Cited by 7 | Viewed by 2274 | PDF Full-text (849 KB) | HTML Full-text | XML Full-text
Abstract
The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results [...] Read more.
The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi0.4Fe0.6O2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O2 sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle
Self-Balancing Position-Sensitive Detector (SBPSD)
Sensors 2015, 15(7), 17483-17494; https://doi.org/10.3390/s150717483
Received: 3 June 2015 / Revised: 11 July 2015 / Accepted: 15 July 2015 / Published: 20 July 2015
Cited by 1 | Viewed by 2104 | PDF Full-text (1628 KB) | HTML Full-text | XML Full-text
Abstract
Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light [...] Read more.
Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light spot. An innovative type of optical position sensor was developed using two back-to-back connected photodiodes. These so called self-balancing position-sensitive detectors (SBPSDs) eliminate the need for external readout circuitry entirely. Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device. PSDs are commercially available only up to a length of 37 mm. Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
A Geospatial Semantic Enrichment and Query Service for Geotagged Photographs
Sensors 2015, 15(7), 17470-17482; https://doi.org/10.3390/s150717470
Received: 7 May 2015 / Revised: 10 July 2015 / Accepted: 13 July 2015 / Published: 20 July 2015
Cited by 1 | Viewed by 2269 | PDF Full-text (823 KB) | HTML Full-text | XML Full-text
Abstract
With the increasing abundance of technologies and smart devices, equipped with a multitude of sensors for sensing the environment around them, information creation and consumption has now become effortless. This, in particular, is the case for photographs with vast amounts being created and [...] Read more.
With the increasing abundance of technologies and smart devices, equipped with a multitude of sensors for sensing the environment around them, information creation and consumption has now become effortless. This, in particular, is the case for photographs with vast amounts being created and shared every day. For example, at the time of this writing, Instagram users upload 70 million photographs a day. Nevertheless, it still remains a challenge to discover the “right” information for the appropriate purpose. This paper describes an approach to create semantic geospatial metadata for photographs, which can facilitate photograph search and discovery. To achieve this we have developed and implemented a semantic geospatial data model by which a photograph can be enrich with geospatial metadata extracted from several geospatial data sources based on the raw low-level geo-metadata from a smartphone photograph. We present the details of our method and implementation for searching and querying the semantic geospatial metadata repository to enable a user or third party system to find the information they are looking for. Full article
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Open AccessArticle
A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters
Sensors 2015, 15(7), 17453-17469; https://doi.org/10.3390/s150717453
Received: 28 April 2015 / Revised: 5 July 2015 / Accepted: 6 July 2015 / Published: 20 July 2015
Cited by 4 | Viewed by 2250 | PDF Full-text (4560 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and [...] Read more.
This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. Full article
(This article belongs to the Special Issue UAV Sensors for Environmental Monitoring) Printed Edition available
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Open AccessArticle
A Method for Oscillation Errors Restriction of SINS Based on Forecasted Time Series
Sensors 2015, 15(7), 17433-17452; https://doi.org/10.3390/s150717433
Received: 23 June 2015 / Revised: 13 July 2015 / Accepted: 15 July 2015 / Published: 17 July 2015
Cited by 3 | Viewed by 2422 | PDF Full-text (1383 KB) | HTML Full-text | XML Full-text
Abstract
Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of [...] Read more.
Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of SINS based on forecasted time series is proposed by analyzing the characteristics of periodic oscillation errors. The innovative method gains multiple sets of navigation solutions with different phase delays in virtue of the forecasted time series acquired through the measurement data of the inertial measurement unit (IMU). With the help of curve-fitting based on least square method, the forecasted time series is obtained while distinguishing and removing small angular motion interference in the process of initial alignment. Finally, the periodic oscillation errors are restricted on account of the principle of eliminating the periodic oscillation signal with a half-wave delay by mean value. Simulation and test results show that the method has good performance in restricting the Schuler, Foucault, and Earth oscillation errors of SINS. Full article
(This article belongs to the Special Issue Inertial Sensors and Systems)
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Open AccessArticle
A New Method to Evaluate Surface Defects with an Electromagnetic Acoustic Transducer
Sensors 2015, 15(7), 17420-17432; https://doi.org/10.3390/s150717420
Received: 31 May 2015 / Revised: 7 July 2015 / Accepted: 8 July 2015 / Published: 17 July 2015
Cited by 2 | Viewed by 1967 | PDF Full-text (1517 KB) | HTML Full-text | XML Full-text
Abstract
Characterizing a surface defect is very crucial in non-destructive testing (NDT). We employ an electromagnetic acoustic transducer (EMAT) to detect the surface defect of a nonmagnetic material. An appropriate feature that can avoid the interference of the human factor is vital for evaluating [...] Read more.
Characterizing a surface defect is very crucial in non-destructive testing (NDT). We employ an electromagnetic acoustic transducer (EMAT) to detect the surface defect of a nonmagnetic material. An appropriate feature that can avoid the interference of the human factor is vital for evaluating the crack quantitatively. Moreover, it can also reduce the influence of other factors, such as the lift-off, during the testing. In this paper, we conduct experiments at various depths of surface cracks in an aluminum plate, and a new feature, lift-off slope (LOS), is put forward for the theoretical and experimental analyses of the lift-off effect on the receiving signals. Besides, by changing the lift-off between the receiving probe and the sample for testing, a new method is adopted to evaluate surface defects with the EMAT. Compared with other features, the theoretical and experimental results show that the feature lift-off slope has many advantages prior to the other features for evaluating the surface defect with the EMAT. This can reduce the lift-off effect of one probe. Meanwhile, it is not essential to measure the signal without defects. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Formation Flight of Multiple UAVs via Onboard Sensor Information Sharing
Sensors 2015, 15(7), 17397-17419; https://doi.org/10.3390/s150717397
Received: 5 June 2015 / Revised: 13 July 2015 / Accepted: 14 July 2015 / Published: 17 July 2015
Cited by 8 | Viewed by 2955 | PDF Full-text (7494 KB) | HTML Full-text | XML Full-text
Abstract
To monitor large areas or simultaneously measure multiple points, multiple unmanned aerial vehicles (UAVs) must be flown in formation. To perform such flights, sensor information generated by each UAV should be shared via communications. Although a variety of studies have focused on the [...] Read more.
To monitor large areas or simultaneously measure multiple points, multiple unmanned aerial vehicles (UAVs) must be flown in formation. To perform such flights, sensor information generated by each UAV should be shared via communications. Although a variety of studies have focused on the algorithms for formation flight, these studies have mainly demonstrated the performance of formation flight using numerical simulations or ground robots, which do not reflect the dynamic characteristics of UAVs. In this study, an onboard sensor information sharing system and formation flight algorithms for multiple UAVs are proposed. The communication delays of radiofrequency (RF) telemetry are analyzed to enable the implementation of the onboard sensor information sharing system. Using the sensor information sharing, the formation guidance law for multiple UAVs, which includes both a circular and close formation, is designed. The hardware system, which includes avionics and an airframe, is constructed for the proposed multi-UAV platform. A numerical simulation is performed to demonstrate the performance of the formation flight guidance and control system for multiple UAVs. Finally, a flight test is conducted to verify the proposed algorithm for the multi-UAV system. Full article
(This article belongs to the Special Issue UAV Sensors for Environmental Monitoring) Printed Edition available
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Open AccessArticle
AF-DHNN: Fuzzy Clustering and Inference-Based Node Fault Diagnosis Method for Fire Detection
Sensors 2015, 15(7), 17366-17396; https://doi.org/10.3390/s150717366
Received: 20 April 2015 / Revised: 13 July 2015 / Accepted: 14 July 2015 / Published: 17 July 2015
Cited by 4 | Viewed by 2202 | PDF Full-text (1325 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks (WSNs) have been utilized for node fault diagnosis in the fire detection field since the 1990s. However, the traditional methods have some problems, including complicated system structures, intensive computation needs, unsteady data detection and local minimum values. In this paper, [...] Read more.
Wireless Sensor Networks (WSNs) have been utilized for node fault diagnosis in the fire detection field since the 1990s. However, the traditional methods have some problems, including complicated system structures, intensive computation needs, unsteady data detection and local minimum values. In this paper, a new diagnosis mechanism for WSN nodes is proposed, which is based on fuzzy theory and an Adaptive Fuzzy Discrete Hopfield Neural Network (AF-DHNN). First, the original status of each sensor over time is obtained with two features. One is the root mean square of the filtered signal (FRMS), the other is the normalized summation of the positive amplitudes of the difference spectrum between the measured signal and the healthy one (NSDS). Secondly, distributed fuzzy inference is introduced. The evident abnormal nodes’ status is pre-alarmed to save time. Thirdly, according to the dimensions of the diagnostic data, an adaptive diagnostic status system is established with a Fuzzy C-Means Algorithm (FCMA) and Sorting and Classification Algorithm to reducing the complexity of the fault determination. Fourthly, a Discrete Hopfield Neural Network (DHNN) with iterations is improved with the optimization of the sensors’ detected status information and standard diagnostic levels, with which the associative memory is achieved, and the search efficiency is improved. The experimental results show that the AF-DHNN method can diagnose abnormal WSN node faults promptly and effectively, which improves the WSN reliability. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle
Heterogeneous Multiple Sensors Joint Tracking of Maneuvering Target in Clutter
Sensors 2015, 15(7), 17350-17365; https://doi.org/10.3390/s150717350
Received: 12 May 2015 / Revised: 13 July 2015 / Accepted: 13 July 2015 / Published: 17 July 2015
Cited by 9 | Viewed by 1981 | PDF Full-text (798 KB) | HTML Full-text | XML Full-text
Abstract
To solve the problem of tracking maneuvering airborne targets in the presence of clutter, an improved interacting multiple model probability data association algorithm (IMMPDA-MDCM) using radar/IR sensors fusion is proposed. Under the architecture of the proposed algorithm, the radar/IR centralized fusion tracking scheme [...] Read more.
To solve the problem of tracking maneuvering airborne targets in the presence of clutter, an improved interacting multiple model probability data association algorithm (IMMPDA-MDCM) using radar/IR sensors fusion is proposed. Under the architecture of the proposed algorithm, the radar/IR centralized fusion tracking scheme of IMMPDA-MDCM is designed to guarantee the observability of the target state. The interacting multiple model (IMM) deals with the model switching. The modified debiased converted measurement (MDCM) filter accounts for non-linearity in the dynamic system models, and reduces the effect of measurement noise on the covariance effectively. The probability data association (PDA) handles data association and measurement uncertainties in clutter. The simulation results show that the proposed algorithm can improve the tracking precision for maneuvering target in clutters, and has higher tracking precision than the traditional IMMPDA based on EKF and IMMPDA based on DCM algorithm. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models
Sensors 2015, 15(7), 17329-17349; https://doi.org/10.3390/s150717329
Received: 19 May 2015 / Revised: 17 June 2015 / Accepted: 9 July 2015 / Published: 17 July 2015
Cited by 29 | Viewed by 2680 | PDF Full-text (5257 KB) | HTML Full-text | XML Full-text
Abstract
Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method [...] Read more.
Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively. Full article
(This article belongs to the Section Remote Sensors, Control, and Telemetry)
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Open AccessArticle
Design of a High-Performance Micro Integrated Surface Plasmon Resonance Sensor Based on Silicon-On-Insulator Rib Waveguide Array
Sensors 2015, 15(7), 17313-17328; https://doi.org/10.3390/s150717313
Received: 11 May 2015 / Revised: 6 July 2015 / Accepted: 10 July 2015 / Published: 16 July 2015
Cited by 10 | Viewed by 2525 | PDF Full-text (1818 KB) | HTML Full-text | XML Full-text
Abstract
Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. [...] Read more.
Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. With the advantages of SOI rib waveguide and the silicon microfabrication technology, an array of the SPR sensors can be composed to implement wavelength interrogation of the sensors’ output signal, so the spectrometer or other bulky and expensive equipment are not necessary, which enables the SPR sensor to realize the miniaturization and integration of the entire sensing system. The performances of the SPR sensor element are verified by using the two-dimensional finite-different time-domain method. The parameters of the sensor element and the array are optimized for the achievement of high performance for biochemical sensing application. As a typical example, a single bimetallic SPR sensor with 3 nm Au over 32 nm Al possesses a high sensitivity of 3.968 × 104 nm/RIU, a detection-accuracy of 14.7 μm−1. For a uniparted SPR sensor, it can achieve a detection limit of 5.04 × 10−7 RIU. With the relative power measurement accuracy of 0.01 dB, the refractive index variation of 1.14 × 10−5 RIU can be detected by the SPR sensor array. Full article
(This article belongs to the Special Issue Silicon Based Optical Sensors)
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Open AccessArticle
Design and Optimization of SiON Ring Resonator-Based Biosensors for Aflatoxin M1 Detection
Sensors 2015, 15(7), 17300-17312; https://doi.org/10.3390/s150717300
Received: 31 May 2015 / Revised: 10 July 2015 / Accepted: 13 July 2015 / Published: 16 July 2015
Cited by 28 | Viewed by 2446 | PDF Full-text (2358 KB) | HTML Full-text | XML Full-text
Abstract
In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10−6 refractive index units (RIU). We tested various samples [...] Read more.
In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10−6 refractive index units (RIU). We tested various samples with different SiON refractive indexes as well as the waveguide dimensions for selecting the sensor with the best performance. Propagation losses and bending losses have been measured on test structures, along with a complete characterization of the resonator’s performances. Sensitivities and limit of detection (LOD) were also measured using glucose-water solutions and compared with expected results from simulations. Finally, we functionalized the resonator and performed sensing experiments with Aflatoxin M1 (AFM1). We were able to detect the binding of aflatoxin for concentrations as low as 12.5 nm. The results open up the path for designing cost-effective biosensors for a fast and reliable sensitive analysis of AFM1 in milk. Full article
(This article belongs to the Special Issue Silicon Based Optical Sensors)
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Open AccessArticle
VisitSense: Sensing Place Visit Patterns from Ambient Radio on Smartphones for Targeted Mobile Ads in Shopping Malls
Sensors 2015, 15(7), 17274-17299; https://doi.org/10.3390/s150717274
Received: 6 May 2015 / Revised: 20 June 2015 / Accepted: 9 July 2015 / Published: 16 July 2015
Cited by 5 | Viewed by 2335 | PDF Full-text (2026 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we introduce a novel smartphone framework called VisitSense that automatically detects and predicts a smartphone user’s place visits from ambient radio to enable behavioral targeting for mobile ads in large shopping malls. VisitSense enables mobile app developers to adopt visit-pattern-aware [...] Read more.
In this paper, we introduce a novel smartphone framework called VisitSense that automatically detects and predicts a smartphone user’s place visits from ambient radio to enable behavioral targeting for mobile ads in large shopping malls. VisitSense enables mobile app developers to adopt visit-pattern-aware mobile advertising for shopping mall visitors in their apps. It also benefits mobile users by allowing them to receive highly relevant mobile ads that are aware of their place visit patterns in shopping malls. To achieve the goal, VisitSense employs accurate visit detection and prediction methods. For accurate visit detection, we develop a change-based detection method to take into consideration the stability change of ambient radio and the mobility change of users. It performs well in large shopping malls where ambient radio is quite noisy and causes existing algorithms to easily fail. In addition, we proposed a causality-based visit prediction model to capture the causality in the sequential visit patterns for effective prediction. We have developed a VisitSense prototype system, and a visit-pattern-aware mobile advertising application that is based on it. Furthermore, we deploy the system in the COEX Mall, one of the largest shopping malls in Korea, and conduct diverse experiments to show the effectiveness of VisitSense. Full article
(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)
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Open AccessArticle
Infrared Thermography to Evaluate Heat Tolerance in Different Genetic Groups of Lambs
Sensors 2015, 15(7), 17258-17273; https://doi.org/10.3390/s150717258
Received: 6 March 2015 / Revised: 11 July 2015 / Accepted: 13 July 2015 / Published: 16 July 2015
Cited by 16 | Viewed by 1918 | PDF Full-text (796 KB) | HTML Full-text | XML Full-text
Abstract
Heat stress is considered a limiting factor for sheep production. We used information from physiological characteristics linked to heat tolerance to determine whether infrared thermography temperatures were able to separate groups of animals and determine the most important variables in this differentiation. Forty-eight [...] Read more.
Heat stress is considered a limiting factor for sheep production. We used information from physiological characteristics linked to heat tolerance to determine whether infrared thermography temperatures were able to separate groups of animals and determine the most important variables in this differentiation. Forty-eight four-month-old male lambs from eight genetic groups were used. Physiological (rectal temperature–RT, heart rate–HR, respiratory rate–RR) and blood traits, infrared thermography temperatures, heat tolerance indices, body measurements, weight and carcass traits were measured. Statistical analyses included variance, correlations, factor, discrimination and regression. Observing the correlations between physiological characteristics (RT, RR and HR) with temperatures measured by infrared thermography, regions for further studies should include the mean temperature of flank, nose and rump. Results show that there are strong relationships between thermograph measurements and RR, RT and HR in lambs, which are suggested to be directly correlated with heat tolerance capacity of the different genetic groups evaluated in this study. The assessment of body surface temperature measured by the thermograph could be used as a noninvasive tool to assess heat tolerance of the animals. Full article
(This article belongs to the Special Issue Frontiers in Infrared Photodetection)
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Open AccessArticle
Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation
Sensors 2015, 15(7), 17241-17257; https://doi.org/10.3390/s150717241
Received: 12 May 2015 / Revised: 3 July 2015 / Accepted: 10 July 2015 / Published: 16 July 2015
Cited by 8 | Viewed by 3386 | PDF Full-text (3542 KB) | HTML Full-text | XML Full-text
Abstract
Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and [...] Read more.
Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel electrode on healthy subjects. The equivalent circuit models and the finite element models of different types of electrode were built based on the measured impedance data of the electrodes to reveal the possible mechanism of electrical stimulation pain. Our results showed that the wet textile electrode could achieve similar stimulation performance as the hydrogel electrode in motor threshold and stimulation comfort. However, the dry textile electrode was found to have very low pain threshold and induced obvious cutaneous painful sensations during stimulation, in comparison to the wet and hydrogel electrodes. Indeed, the finite element modeling results showed that the activation function along the z direction at the depth of dermis epidermis junction of the dry textile electrode was significantly larger than that of the wet and hydrogel electrodes, thus resulting in stronger activation of pain sensing fibers. Future work will be done to make textile electrodes have similar stimulation performance and comfort as hydrogel electrodes. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle
On-Chip Sensing of Thermoelectric Thin Film’s Merit
Sensors 2015, 15(7), 17232-17240; https://doi.org/10.3390/s150717232
Received: 1 May 2015 / Revised: 19 June 2015 / Accepted: 13 July 2015 / Published: 16 July 2015
Cited by 2 | Viewed by 2125 | PDF Full-text (1412 KB) | HTML Full-text | XML Full-text
Abstract
Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based [...] Read more.
Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques. Specifically, e-beam evaporation was used to grow the thermoelectric thin film of Sb2Te3 (100 nm thick). The Seebeck coefficient and the merit of the Sb2Te3 thin film were measured or determined. The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication. Full article
(This article belongs to the Section Physical Sensors)
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