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Sensors, Volume 15, Issue 8 (August 2015), Pages 17827-20944

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Open AccessArticle A Self-Assessment Stereo Capture Model Applicable to the Internet of Things
Sensors 2015, 15(8), 20925-20944; https://doi.org/10.3390/s150820925
Received: 10 July 2015 / Revised: 7 August 2015 / Accepted: 14 August 2015 / Published: 21 August 2015
Cited by 153 | Viewed by 2842 | PDF Full-text (1648 KB) | HTML Full-text | XML Full-text
Abstract
The realization of the Internet of Things greatly depends on the information communication among physical terminal devices and informationalized platforms, such as smart sensors, embedded systems and intelligent networks. Playing an important role in information acquisition, sensors for stereo capture have gained extensive
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The realization of the Internet of Things greatly depends on the information communication among physical terminal devices and informationalized platforms, such as smart sensors, embedded systems and intelligent networks. Playing an important role in information acquisition, sensors for stereo capture have gained extensive attention in various fields. In this paper, we concentrate on promoting such sensors in an intelligent system with self-assessment capability to deal with the distortion and impairment in long-distance shooting applications. The core design is the establishment of the objective evaluation criteria that can reliably predict shooting quality with different camera configurations. Two types of stereo capture systems—toed-in camera configuration and parallel camera configuration—are taken into consideration respectively. The experimental results show that the proposed evaluation criteria can effectively predict the visual perception of stereo capture quality for long-distance shooting. Full article
(This article belongs to the Special Issue Identification, Information & Knowledge in the Internet of Things)
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Open AccessArticle Reliable Fusion of Stereo Matching and Depth Sensor for High Quality Dense Depth Maps
Sensors 2015, 15(8), 20894-20924; https://doi.org/10.3390/s150820894
Received: 23 June 2015 / Revised: 7 August 2015 / Accepted: 17 August 2015 / Published: 21 August 2015
Cited by 5 | Viewed by 2388 | PDF Full-text (22352 KB) | HTML Full-text | XML Full-text
Abstract
Depth estimation is a classical problem in computer vision, which typically relies on either a depth sensor or stereo matching alone. The depth sensor provides real-time estimates in repetitive and textureless regions where stereo matching is not effective. However, stereo matching can obtain
[...] Read more.
Depth estimation is a classical problem in computer vision, which typically relies on either a depth sensor or stereo matching alone. The depth sensor provides real-time estimates in repetitive and textureless regions where stereo matching is not effective. However, stereo matching can obtain more accurate results in rich texture regions and object boundaries where the depth sensor often fails. We fuse stereo matching and the depth sensor using their complementary characteristics to improve the depth estimation. Here, texture information is incorporated as a constraint to restrict the pixel’s scope of potential disparities and to reduce noise in repetitive and textureless regions. Furthermore, a novel pseudo-two-layer model is used to represent the relationship between disparities in different pixels and segments. It is more robust to luminance variation by treating information obtained from a depth sensor as prior knowledge. Segmentation is viewed as a soft constraint to reduce ambiguities caused by under- or over-segmentation. Compared to the average error rate 3.27% of the previous state-of-the-art methods, our method provides an average error rate of 2.61% on the Middlebury datasets, which shows that our method performs almost 20% better than other “fused” algorithms in the aspect of precision. Full article
(This article belongs to the Special Issue Imaging: Sensors and Technologies) Printed Edition available
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Open AccessArticle A Context-Aware EEG Headset System for Early Detection of Driver Drowsiness
Sensors 2015, 15(8), 20873-20893; https://doi.org/10.3390/s150820873
Received: 6 July 2015 / Revised: 30 July 2015 / Accepted: 18 August 2015 / Published: 21 August 2015
Cited by 15 | Viewed by 2981 | PDF Full-text (1567 KB) | HTML Full-text | XML Full-text
Abstract
Driver drowsiness is a major cause of mortality in traffic accidents worldwide. Electroencephalographic (EEG) signal, which reflects the brain activities, is more directly related to drowsiness. Thus, many Brain-Machine-Interface (BMI) systems have been proposed to detect driver drowsiness. However, detecting driver drowsiness at
[...] Read more.
Driver drowsiness is a major cause of mortality in traffic accidents worldwide. Electroencephalographic (EEG) signal, which reflects the brain activities, is more directly related to drowsiness. Thus, many Brain-Machine-Interface (BMI) systems have been proposed to detect driver drowsiness. However, detecting driver drowsiness at its early stage poses a major practical hurdle when using existing BMI systems. This study proposes a context-aware BMI system aimed to detect driver drowsiness at its early stage by enriching the EEG data with the intensity of head-movements. The proposed system is carefully designed for low-power consumption with on-chip feature extraction and low energy Bluetooth connection. Also, the proposed system is implemented using JAVA programming language as a mobile application for on-line analysis. In total, 266 datasets obtained from six subjects who participated in a one-hour monotonous driving simulation experiment were used to evaluate this system. According to a video-based reference, the proposed system obtained an overall detection accuracy of 82.71% for classifying alert and slightly drowsy events by using EEG data alone and 96.24% by using the hybrid data of head-movement and EEG. These results indicate that the combination of EEG data and head-movement contextual information constitutes a robust solution for the early detection of driver drowsiness. Full article
(This article belongs to the Special Issue Wearable Sensors)
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Open AccessArticle Lipid Multilayer Grating Arrays Integrated by Nanointaglio for Vapor Sensing by an Optical Nose
Sensors 2015, 15(8), 20863-20872; https://doi.org/10.3390/s150820863
Received: 3 July 2015 / Revised: 29 July 2015 / Accepted: 17 August 2015 / Published: 21 August 2015
Cited by 3 | Viewed by 2049 | PDF Full-text (722 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Lipid multilayer gratings are recently invented nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. Here, we show that nanointaglio is suitable
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Lipid multilayer gratings are recently invented nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. Here, we show that nanointaglio is suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone) in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used here is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose. Full article
(This article belongs to the Special Issue Nanomechanics for Sensing and Spectrometry)
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Open AccessArticle Distance-Dependent Multimodal Image Registration for Agriculture Tasks
Sensors 2015, 15(8), 20845-20862; https://doi.org/10.3390/s150820845
Received: 1 May 2015 / Revised: 11 August 2015 / Accepted: 11 August 2015 / Published: 21 August 2015
Cited by 3 | Viewed by 1697 | PDF Full-text (6024 KB) | HTML Full-text | XML Full-text
Abstract
Image registration is the process of aligning two or more images of the same scene taken at different times; from different viewpoints; and/or by different sensors. This research focuses on developing a practical method for automatic image registration for agricultural systems that use
[...] Read more.
Image registration is the process of aligning two or more images of the same scene taken at different times; from different viewpoints; and/or by different sensors. This research focuses on developing a practical method for automatic image registration for agricultural systems that use multimodal sensory systems and operate in natural environments. While not limited to any particular modalities; here we focus on systems with visual and thermal sensory inputs. Our approach is based on pre-calibrating a distance-dependent transformation matrix (DDTM) between the sensors; and representing it in a compact way by regressing the distance-dependent coefficients as distance-dependent functions. The DDTM is measured by calculating a projective transformation matrix for varying distances between the sensors and possible targets. To do so we designed a unique experimental setup including unique Artificial Control Points (ACPs) and their detection algorithms for the two sensors. We demonstrate the utility of our approach using different experiments and evaluation criteria. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Efficient Implementation of a Symbol Timing Estimator for Broadband PLC
Sensors 2015, 15(8), 20825-20844; https://doi.org/10.3390/s150820825
Received: 26 June 2015 / Revised: 27 July 2015 / Accepted: 14 August 2015 / Published: 21 August 2015
Cited by 3 | Viewed by 1843 | PDF Full-text (1718 KB) | HTML Full-text | XML Full-text
Abstract
Broadband Power Line Communications (PLC) have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless,
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Broadband Power Line Communications (PLC) have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Towards a Low-Cost Remote Memory Attestation for the Smart Grid
Sensors 2015, 15(8), 20799-20824; https://doi.org/10.3390/s150820799
Received: 27 June 2015 / Revised: 9 August 2015 / Accepted: 13 August 2015 / Published: 21 August 2015
Cited by 12 | Viewed by 2073 | PDF Full-text (500 KB) | HTML Full-text | XML Full-text
Abstract
In the smart grid, measurement devices may be compromised by adversaries, and their operations could be disrupted by attacks. A number of schemes to efficiently and accurately detect these compromised devices remotely have been proposed. Nonetheless, most of the existing schemes detecting compromised
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In the smart grid, measurement devices may be compromised by adversaries, and their operations could be disrupted by attacks. A number of schemes to efficiently and accurately detect these compromised devices remotely have been proposed. Nonetheless, most of the existing schemes detecting compromised devices depend on the incremental response time in the attestation process, which are sensitive to data transmission delay and lead to high computation and network overhead. To address the issue, in this paper, we propose a low-cost remote memory attestation scheme (LRMA), which can efficiently and accurately detect compromised smart meters considering real-time network delay and achieve low computation and network overhead. In LRMA, the impact of real-time network delay on detecting compromised nodes can be eliminated via investigating the time differences reported from relay nodes. Furthermore, the attestation frequency in LRMA is dynamically adjusted with the compromised probability of each node, and then, the total number of attestations could be reduced while low computation and network overhead can be achieved. Through a combination of extensive theoretical analysis and evaluations, our data demonstrate that our proposed scheme can achieve better detection capacity and lower computation and network overhead in comparison to existing schemes. Full article
(This article belongs to the Special Issue Identification, Information & Knowledge in the Internet of Things)
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Open AccessArticle GPS/DR Error Estimation for Autonomous Vehicle Localization
Sensors 2015, 15(8), 20779-20798; https://doi.org/10.3390/s150820779
Received: 16 June 2015 / Revised: 30 July 2015 / Accepted: 11 August 2015 / Published: 21 August 2015
Cited by 21 | Viewed by 3198 | PDF Full-text (1356 KB) | HTML Full-text | XML Full-text
Abstract
Autonomous vehicles require highly reliable navigation capabilities. For example, a lane-following method cannot be applied in an intersection without lanes, and since typical lane detection is performed using a straight-line model, errors can occur when the lateral distance is estimated in curved sections
[...] Read more.
Autonomous vehicles require highly reliable navigation capabilities. For example, a lane-following method cannot be applied in an intersection without lanes, and since typical lane detection is performed using a straight-line model, errors can occur when the lateral distance is estimated in curved sections due to a model mismatch. Therefore, this paper proposes a localization method that uses GPS/DR error estimation based on a lane detection method with curved lane models, stop line detection, and curve matching in order to improve the performance during waypoint following procedures. The advantage of using the proposed method is that position information can be provided for autonomous driving through intersections, in sections with sharp curves, and in curved sections following a straight section. The proposed method was applied in autonomous vehicles at an experimental site to evaluate its performance, and the results indicate that the positioning achieved accuracy at the sub-meter level. Full article
(This article belongs to the Special Issue Sensors in New Road Vehicles)
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Open AccessArticle High-Performance Motion Estimation for Image Sensors with Video Compression
Sensors 2015, 15(8), 20752-20778; https://doi.org/10.3390/s150820752
Received: 29 June 2015 / Revised: 5 August 2015 / Accepted: 13 August 2015 / Published: 21 August 2015
Cited by 2 | Viewed by 1687 | PDF Full-text (949 KB) | HTML Full-text | XML Full-text
Abstract
It is important to reduce the time cost of video compression for image sensors in video sensor network. Motion estimation (ME) is the most time-consuming part in video compression. Previous work on ME exploited intra-frame data reuse in a reference frame to improve
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It is important to reduce the time cost of video compression for image sensors in video sensor network. Motion estimation (ME) is the most time-consuming part in video compression. Previous work on ME exploited intra-frame data reuse in a reference frame to improve the time efficiency but neglected inter-frame data reuse. We propose a novel inter-frame data reuse scheme which can exploit both intra-frame and inter-frame data reuse for ME in video compression (VC-ME). Pixels of reconstructed frames are kept on-chip until they are used by the next current frame to avoid off-chip memory access. On-chip buffers with smart schedules of data access are designed to perform the new data reuse scheme. Three levels of the proposed inter-frame data reuse scheme are presented and analyzed. They give different choices with tradeoff between off-chip bandwidth requirement and on-chip memory size. All three levels have better data reuse efficiency than their intra-frame counterparts, so off-chip memory traffic is reduced effectively. Comparing the new inter-frame data reuse scheme with the traditional intra-frame data reuse scheme, the memory traffic can be reduced by 50% for VC-ME. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle ECG Sensor Card with Evolving RBP Algorithms for Human Verification
Sensors 2015, 15(8), 20730-20751; https://doi.org/10.3390/s150820730
Received: 14 June 2015 / Revised: 28 July 2015 / Accepted: 6 August 2015 / Published: 21 August 2015
Cited by 3 | Viewed by 2416 | PDF Full-text (1077 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
It is known that cardiac and respiratory rhythms in electrocardiograms (ECGs) are highly nonlinear and non-stationary. As a result, most traditional time-domain algorithms are inadequate for characterizing the complex dynamics of the ECG. This paper proposes a new ECG sensor card and a
[...] Read more.
It is known that cardiac and respiratory rhythms in electrocardiograms (ECGs) are highly nonlinear and non-stationary. As a result, most traditional time-domain algorithms are inadequate for characterizing the complex dynamics of the ECG. This paper proposes a new ECG sensor card and a statistical-based ECG algorithm, with the aid of a reduced binary pattern (RBP), with the aim of achieving faster ECG human identity recognition with high accuracy. The proposed algorithm has one advantage that previous ECG algorithms lack—the waveform complex information and de-noising preprocessing can be bypassed; therefore, it is more suitable for non-stationary ECG signals. Experimental results tested on two public ECG databases (MIT-BIH) from MIT University confirm that the proposed scheme is feasible with excellent accuracy, low complexity, and speedy processing. To be more specific, the advanced RBP algorithm achieves high accuracy in human identity recognition and is executed at least nine times faster than previous algorithms. Moreover, based on the test results from a long-term ECG database, the evolving RBP algorithm also demonstrates superior capability in handling long-term and non-stationary ECG signals. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Low Power Wireless Smoke Alarm System in Home Fires
Sensors 2015, 15(8), 20717-20729; https://doi.org/10.3390/s150820717
Received: 28 April 2015 / Revised: 24 July 2015 / Accepted: 17 August 2015 / Published: 21 August 2015
Cited by 10 | Viewed by 3653 | PDF Full-text (3034 KB) | HTML Full-text | XML Full-text
Abstract
A novel sensing device for fire detection in domestic environments is presented. The fire detector uses a combination of several sensors that not only detect smoke, but discriminate between different types of smoke. This feature avoids false alarms and warns of different situations.
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A novel sensing device for fire detection in domestic environments is presented. The fire detector uses a combination of several sensors that not only detect smoke, but discriminate between different types of smoke. This feature avoids false alarms and warns of different situations. Power consumption is optimized both in terms of hardware and software, providing a high degree of autonomy of almost five years. Data gathered from the device are transmitted through a wireless communication to a base station. The low cost and compact design provides wide application prospects. Full article
(This article belongs to the Special Issue Sensors for Fire Detection)
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Open AccessArticle Evaluation of the Fourier Frequency Spectrum Peaks of Milk Electrical Conductivity Signals as Indexes to Monitor the Dairy Goats’ Health Status by On-Line Sensors
Sensors 2015, 15(8), 20698-20716; https://doi.org/10.3390/s150820698
Received: 12 May 2015 / Revised: 27 July 2015 / Accepted: 17 August 2015 / Published: 21 August 2015
Cited by 7 | Viewed by 1724 | PDF Full-text (1382 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this study is a further characterization of the electrical conductivity (EC) signal of goat milk, acquired on-line by EC sensors, to identify new indexes representative of the EC variations that can be observed during milking, when considering not healthy (NH)
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The aim of this study is a further characterization of the electrical conductivity (EC) signal of goat milk, acquired on-line by EC sensors, to identify new indexes representative of the EC variations that can be observed during milking, when considering not healthy (NH) glands. Two foremilk gland samples from 42 Saanen goats, were collected for three consecutive weeks and for three different lactation stages (LS: 0–60 Days In Milking (DIM); 61–120 DIM; 121–180 DIM), for a total amount of 1512 samples. Bacteriological analyses and somatic cells counts (SCC) were used to define the health status of the glands. With negative bacteriological analyses and SCC < 1,000,000 cells/mL, glands were classified as healthy. When bacteriological analyses were positive or showed a SCC > 1,000,000 cells/mL, glands were classified as NH. For each milk EC signal, acquired on-line and for each gland considered, the Fourier frequency spectrum of the signal was calculated and three representative frequency peaks were identified. To evaluate data acquired a MIXED procedure was used considering the HS, LS and LS × HS as explanatory variables in the statistical model.Results showed that the studied frequency peaks had a significant relationship with the gland’s health status. Results also explained how the milk EC signals’ pattern change in case of NH glands. In fact, it is characterized by slower fluctuations (due to the lower frequencies of the peaks) and by an irregular trend (due to the higher amplitudes of all the main frequency peaks). Therefore, these frequency peaks could be used as new indexes to improve the performances of algorithms based on multivariate models which evaluate the health status of dairy goats through the use of gland milk EC sensors. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Research and Experiments on a Unipolar Capacitive Voltage Sensor
Sensors 2015, 15(8), 20678-20697; https://doi.org/10.3390/s150820678
Received: 9 June 2015 / Revised: 27 July 2015 / Accepted: 12 August 2015 / Published: 21 August 2015
Cited by 5 | Viewed by 1945 | PDF Full-text (2238 KB) | HTML Full-text | XML Full-text
Abstract
Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As
[...] Read more.
Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Ultrahigh-Temperature Regeneration of Long Period Gratings (LPGs) in Boron-Codoped Germanosilicate Optical Fibre
Sensors 2015, 15(8), 20659-20677; https://doi.org/10.3390/s150820659
Received: 11 June 2015 / Revised: 13 July 2015 / Accepted: 14 August 2015 / Published: 20 August 2015
Cited by 3 | Viewed by 1927 | PDF Full-text (671 KB) | HTML Full-text | XML Full-text
Abstract
The regeneration of UV-written long period gratings (LPG) in boron-codoped germanosilicate “W” fibre is demonstrated and studied. They survive temperatures over 1000 °C. Compared with regenerated FBGs fabricated in the same type of fibre, the evolution curves of LPGs during regeneration and post-annealing
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The regeneration of UV-written long period gratings (LPG) in boron-codoped germanosilicate “W” fibre is demonstrated and studied. They survive temperatures over 1000 °C. Compared with regenerated FBGs fabricated in the same type of fibre, the evolution curves of LPGs during regeneration and post-annealing reveal even more detail of glass relaxation. Piece-wise temperature dependence is observed, indicating the onset of a phase transition of glass in the core and inner cladding at ~500 °C and ~250 °C, and the melting of inner cladding between 860 °C and 900 °C. An asymmetric spectral response with increasing and decreasing annealing temperature points to the complex process dependent material system response. Resonant wavelength tuning by adjusting the dwell temperature at which regeneration is undertaken is demonstrated, showing a shorter resonant wavelength and shorter time for stabilisation with higher dwell temperatures. All the regenerated LPGs are nearly strain-insensitive and cannot be tuned by applying loads during annealing as done for regenerated FBGs. Full article
(This article belongs to the Special Issue Sensors for Harsh Environments)
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Open AccessArticle Highly Sensitive Electrochemical Determination of Alfatoxin B1 Using Quantum Dots-Assembled Amplification Labels
Sensors 2015, 15(8), 20648-20658; https://doi.org/10.3390/s150820648
Received: 24 June 2015 / Revised: 6 August 2015 / Accepted: 17 August 2015 / Published: 20 August 2015
Cited by 4 | Viewed by 1502 | PDF Full-text (1137 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A competitive electrochemical immunoassay for highly sensitive detection of AFB1 is demonstrated using layer-by-layer (LBL) assembled quantum dots (QDs) as labels. To investigate the effects of the higher sensitivity of square wave voltammetric stripping (SWV) and of the LBL technique on the proposed
[...] Read more.
A competitive electrochemical immunoassay for highly sensitive detection of AFB1 is demonstrated using layer-by-layer (LBL) assembled quantum dots (QDs) as labels. To investigate the effects of the higher sensitivity of square wave voltammetric stripping (SWV) and of the LBL technique on the proposed immunoassays, the proposed assay was compared to electrochemical (EC) and fluorescent immunoassays, which did not use LBL technology. Peanut samples were analyzed using the three immunoassays. The limits of detection (LODs) were 0.018, 0.046 and 0.212 ng/mL, respectively, while the sensitivities were 0.308, 1.011 and 4.594 ng/mL, respectively. The proposed electrochemical immunoassay displayed a significant improvement in sensitivity, thereby providing a simple and sensitive alternative strategy for determining AFB1 levels in peanut samples. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Model-Based Design of Tree WSNs for Decentralized Detection
Sensors 2015, 15(8), 20608-20647; https://doi.org/10.3390/s150820608
Received: 1 January 2015 / Accepted: 3 August 2015 / Published: 20 August 2015
Cited by 1 | Viewed by 1607 | PDF Full-text (1958 KB) | HTML Full-text | XML Full-text
Abstract
The classical decentralized detection problem of finding the optimal decision rules at the sensor and fusion center, as well as variants that introduce physical channel impairments have been studied extensively in the literature. The deployment of WSNs in decentralized detection applications brings new
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The classical decentralized detection problem of finding the optimal decision rules at the sensor and fusion center, as well as variants that introduce physical channel impairments have been studied extensively in the literature. The deployment of WSNs in decentralized detection applications brings new challenges to the field. Protocols for different communication layers have to be co-designed to optimize the detection performance. In this paper, we consider the communication network design problem for a tree WSN. We pursue a system-level approach where a complete model for the system is developed that captures the interactions between different layers, as well as different sensor quality measures. For network optimization, we propose a hierarchical optimization algorithm that lends itself to the tree structure, requiring only local network information. The proposed design approach shows superior performance over several contentionless and contention-based network design approaches. Full article
(This article belongs to the Special Issue Cyber-Physical Systems)
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Open AccessReview Context Aware Middleware Architectures: Survey and Challenges
Sensors 2015, 15(8), 20570-20607; https://doi.org/10.3390/s150820570
Received: 30 April 2015 / Revised: 12 August 2015 / Accepted: 13 August 2015 / Published: 20 August 2015
Cited by 33 | Viewed by 2865 | PDF Full-text (882 KB) | HTML Full-text | XML Full-text
Abstract
Context aware applications, which can adapt their behaviors to changing environments, are attracting more and more attention. To simplify the complexity of developing applications, context aware middleware, which introduces context awareness into the traditional middleware, is highlighted to provide a homogeneous interface involving
[...] Read more.
Context aware applications, which can adapt their behaviors to changing environments, are attracting more and more attention. To simplify the complexity of developing applications, context aware middleware, which introduces context awareness into the traditional middleware, is highlighted to provide a homogeneous interface involving generic context management solutions. This paper provides a survey of state-of-the-art context aware middleware architectures proposed during the period from 2009 through 2015. First, a preliminary background, such as the principles of context, context awareness, context modelling, and context reasoning, is provided for a comprehensive understanding of context aware middleware. On this basis, an overview of eleven carefully selected middleware architectures is presented and their main features explained. Then, thorough comparisons and analysis of the presented middleware architectures are performed based on technical parameters including architectural style, context abstraction, context reasoning, scalability, fault tolerance, interoperability, service discovery, storage, security & privacy, context awareness level, and cloud-based big data analytics. The analysis shows that there is actually no context aware middleware architecture that complies with all requirements. Finally, challenges are pointed out as open issues for future work. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation
Sensors 2015, 15(8), 20557-20569; https://doi.org/10.3390/s150820557
Received: 25 June 2015 / Revised: 4 August 2015 / Accepted: 11 August 2015 / Published: 20 August 2015
Cited by 3 | Viewed by 1541 | PDF Full-text (1614 KB) | HTML Full-text | XML Full-text
Abstract
Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using
[...] Read more.
Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a 60Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. Full article
(This article belongs to the Special Issue Silicon Based Optical Sensors)
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Open AccessArticle DNA-Redox Cation Interaction Improves the Sensitivity of an Electrochemical Immunosensor for Protein Detection
Sensors 2015, 15(8), 20543-20556; https://doi.org/10.3390/s150820543
Received: 22 June 2015 / Revised: 31 July 2015 / Accepted: 12 August 2015 / Published: 20 August 2015
Cited by 3 | Viewed by 2172 | PDF Full-text (657 KB) | HTML Full-text | XML Full-text
Abstract
A simple DNA-redox cation interaction enhancement strategy has been developed to improve the sensitivity of electrochemical immunosensors for protein detection. Instead of labeling with fluorophores or redox-active groups, the detection antibodies were tethered with DNA single strands. Based on the electrostatic interaction between
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A simple DNA-redox cation interaction enhancement strategy has been developed to improve the sensitivity of electrochemical immunosensors for protein detection. Instead of labeling with fluorophores or redox-active groups, the detection antibodies were tethered with DNA single strands. Based on the electrostatic interaction between redox cations ([Ru(NH3)6]3+) and negatively charged DNA backbone, enhanced electrochemical signals were obtained. Human chorionic gonadotropin (hCG) detection has been performed as a trial analysis. A linear response range up to the concentration of 25 mIU/mL and a detection limit of 1.25 mIU/mL have been achieved, both are comparable with the ultrasensitive enzyme-linked immunosorbent assay (ELISA) tests. The method also shows great selectivity towards hCG over other hormones such as thyroid stimulating hormone (TSH) and follicle stimulating hormone (FSH). By and large, our approach bears the merits of cost effectiveness and simplicity of instrumentation in comparison with conventional optical detection methods. Full article
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Open AccessCorrection Correction: Li, S. et al. Research on a Power Management System for Thermoelectric Generators to Drive Wireless Sensors on a Spindle Unit. Sensors 2014, 14, 12701–12714
Sensors 2015, 15(8), 20541-20542; https://doi.org/10.3390/s150820541
Received: 7 August 2015 / Accepted: 11 August 2015 / Published: 20 August 2015
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Abstract
The authors wish to make the following corrections to this paper [1]. [...] Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Belief Function Based Decision Fusion for Decentralized Target Classification in Wireless Sensor Networks
Sensors 2015, 15(8), 20524-20540; https://doi.org/10.3390/s150820524
Received: 17 June 2015 / Revised: 12 August 2015 / Accepted: 13 August 2015 / Published: 19 August 2015
Cited by 15 | Viewed by 1505 | PDF Full-text (838 KB) | HTML Full-text | XML Full-text
Abstract
Decision fusion in sensor networks enables sensors to improve classification accuracy while reducing the energy consumption and bandwidth demand for data transmission. In this paper, we focus on the decentralized multi-class classification fusion problem in wireless sensor networks (WSNs) and a new simple
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Decision fusion in sensor networks enables sensors to improve classification accuracy while reducing the energy consumption and bandwidth demand for data transmission. In this paper, we focus on the decentralized multi-class classification fusion problem in wireless sensor networks (WSNs) and a new simple but effective decision fusion rule based on belief function theory is proposed. Unlike existing belief function based decision fusion schemes, the proposed approach is compatible with any type of classifier because the basic belief assignments (BBAs) of each sensor are constructed on the basis of the classifier’s training output confusion matrix and real-time observations. We also derive explicit global BBA in the fusion center under Dempster’s combinational rule, making the decision making operation in the fusion center greatly simplified. Also, sending the whole BBA structure to the fusion center is avoided. Experimental results demonstrate that the proposed fusion rule has better performance in fusion accuracy compared with the naïve Bayes rule and weighted majority voting rule. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle Considerations on Circuit Design and Data Acquisition of a Portable Surface Plasmon Resonance Biosensing System
Sensors 2015, 15(8), 20511-20523; https://doi.org/10.3390/s150820511
Received: 15 June 2015 / Revised: 6 August 2015 / Accepted: 7 August 2015 / Published: 19 August 2015
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Abstract
The aim of this study was to develop a circuit for an inexpensive portable biosensing system based on surface plasmon resonance spectroscopy. This portable biosensing system designed for field use is characterized by a special structure which consists of a microfluidic cell incorporating
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The aim of this study was to develop a circuit for an inexpensive portable biosensing system based on surface plasmon resonance spectroscopy. This portable biosensing system designed for field use is characterized by a special structure which consists of a microfluidic cell incorporating a right angle prism functionalized with a biomolecular identification membrane, a laser line generator and a data acquisition circuit board. The data structure, data memory capacity and a line charge-coupled device (CCD) array with a driving circuit for collecting the photoelectric signals are intensively focused on and the high performance analog-to-digital (A/D) converter is comprehensively evaluated. The interface circuit and the photoelectric signal amplifier circuit are first studied to obtain the weak signals from the line CCD array in this experiment. Quantitative measurements for validating the sensitivity of the biosensing system were implemented using ethanol solutions of various concentrations indicated by volume fractions of 5%, 8%, 15%, 20%, 25%, and 30%, respectively, without a biomembrane immobilized on the surface of the SPR sensor. The experiments demonstrated that it is possible to detect a change in the refractive index of an ethanol solution with a sensitivity of 4.99838 × 105 ΔRU/RI in terms of the changes in delta response unit with refractive index using this SPR biosensing system, whereby the theoretical limit of detection of 3.3537 × 10−5 refractive index unit (RIU) and a high linearity at the correlation coefficient of 0.98065. The results obtained from a series of tests confirmed the practicality of this cost-effective portable SPR biosensing system. Full article
(This article belongs to the Special Issue Label-Free Sensing) Printed Edition available
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Open AccessArticle A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand
Sensors 2015, 15(8), 20501-20510; https://doi.org/10.3390/s150820501
Received: 8 July 2015 / Revised: 4 August 2015 / Accepted: 13 August 2015 / Published: 19 August 2015
Cited by 6 | Viewed by 2251 | PDF Full-text (1475 KB) | HTML Full-text | XML Full-text
Abstract
A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of
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A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5–7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5–1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise
Sensors 2015, 15(8), 20480-20500; https://doi.org/10.3390/s150820480
Received: 23 April 2015 / Revised: 22 July 2015 / Accepted: 5 August 2015 / Published: 19 August 2015
Cited by 3 | Viewed by 1849 | PDF Full-text (472 KB) | HTML Full-text | XML Full-text
Abstract
This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the
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This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R2 = 0:77 to R2 = 0:98 (for blood lactate) and from R2 = 0:81 to R2 = 0:97 (for oxygen uptake) were obtained when using random forest regressors. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle In Situ 3D Segmentation of Individual Plant Leaves Using a RGB-D Camera for Agricultural Automation
Sensors 2015, 15(8), 20463-20479; https://doi.org/10.3390/s150820463
Received: 1 June 2015 / Revised: 15 July 2015 / Accepted: 23 July 2015 / Published: 19 August 2015
Cited by 20 | Viewed by 2431 | PDF Full-text (3206 KB) | HTML Full-text | XML Full-text
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In this paper, we present a challenging task of 3D segmentation of individual plant leaves from occlusions in the complicated natural scene. Depth data of plant leaves is introduced to improve the robustness of plant leaf segmentation. The low cost RGB-D camera is
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In this paper, we present a challenging task of 3D segmentation of individual plant leaves from occlusions in the complicated natural scene. Depth data of plant leaves is introduced to improve the robustness of plant leaf segmentation. The low cost RGB-D camera is utilized to capture depth and color image in fields. Mean shift clustering is applied to segment plant leaves in depth image. Plant leaves are extracted from the natural background by examining vegetation of the candidate segments produced by mean shift. Subsequently, individual leaves are segmented from occlusions by active contour models. Automatic initialization of the active contour models is implemented by calculating the center of divergence from the gradient vector field of depth image. The proposed segmentation scheme is tested through experiments under greenhouse conditions. The overall segmentation rate is 87.97% while segmentation rates for single and occluded leaves are 92.10% and 86.67%, respectively. Approximately half of the experimental results show segmentation rates of individual leaves higher than 90%. Nevertheless, the proposed method is able to segment individual leaves from heavy occlusions. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Use of Low-Cost Acquisition Systems with an Embedded Linux Device for Volcanic Monitoring
Sensors 2015, 15(8), 20436-20462; https://doi.org/10.3390/s150820436
Received: 12 June 2015 / Revised: 7 August 2015 / Accepted: 10 August 2015 / Published: 19 August 2015
Cited by 7 | Viewed by 2248 | PDF Full-text (5573 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC)
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This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Influence of Errors in Tactile Sensors on Some High Level Parameters Used for Manipulation with Robotic Hands
Sensors 2015, 15(8), 20409-20435; https://doi.org/10.3390/s150820409
Received: 20 April 2015 / Revised: 20 July 2015 / Accepted: 10 August 2015 / Published: 19 August 2015
Cited by 5 | Viewed by 1658 | PDF Full-text (1707 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensors suffer from many types of interference and errors like crosstalk, non-linearity, drift or hysteresis, therefore calibration should be carried out to compensate for these deviations. However, this procedure is difficult in sensors mounted on artificial hands for robots or prosthetics for
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Tactile sensors suffer from many types of interference and errors like crosstalk, non-linearity, drift or hysteresis, therefore calibration should be carried out to compensate for these deviations. However, this procedure is difficult in sensors mounted on artificial hands for robots or prosthetics for instance, where the sensor usually bends to cover a curved surface. Moreover, the calibration procedure should be repeated often because the correction parameters are easily altered by time and surrounding conditions. Furthermore, this intensive and complex calibration could be less determinant, or at least simpler. This is because manipulation algorithms do not commonly use the whole data set from the tactile image, but only a few parameters such as the moments of the tactile image. These parameters could be changed less by common errors and interferences, or at least their variations could be in the order of those caused by accepted limitations, like reduced spatial resolution. This paper shows results from experiments to support this idea. The experiments are carried out with a high performance commercial sensor as well as with a low-cost error-prone sensor built with a common procedure in robotics. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Identification of Foot Pathologies Based on Plantar Pressure Asymmetry
Sensors 2015, 15(8), 20392-20408; https://doi.org/10.3390/s150820392
Received: 13 March 2015 / Revised: 7 August 2015 / Accepted: 11 August 2015 / Published: 18 August 2015
Cited by 21 | Viewed by 3294 | PDF Full-text (1685 KB) | HTML Full-text | XML Full-text
Abstract
Foot pathologies can negatively influence foot function, consequently impairing gait during daily activity, and severely impacting an individual’s quality of life. These pathologies are often painful and correspond with high or abnormal plantar pressure, which can result in asymmetry in the pressure distribution
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Foot pathologies can negatively influence foot function, consequently impairing gait during daily activity, and severely impacting an individual’s quality of life. These pathologies are often painful and correspond with high or abnormal plantar pressure, which can result in asymmetry in the pressure distribution between the two feet. There is currently no general consensus on the presence of asymmetry in able-bodied gait, and plantar pressure analysis during gait is in dire need of a standardized method to quantify asymmetry. This paper investigates the use of plantar pressure asymmetry for pathological gait diagnosis. The results of this study involving plantar pressure analysis in fifty one participants (31 healthy and 20 with foot pathologies) support the presence of plantar pressure asymmetry in normal gait. A higher level of asymmetry was detected at the majority of the regions in the feet of the pathological population, including statistically significant differences in the plantar pressure asymmetry in two regions of the foot, metatarsophalangeal joint 3 (MPJ3) and the lateral heel. Quantification of plantar pressure asymmetry may prove to be useful for the identification and diagnosis of various foot pathologies. Full article
(This article belongs to the collection Sensors for Globalized Healthy Living and Wellbeing)
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Open AccessArticle Fuzzy Logic-Based Guaranteed Lifetime Protocol for Real-Time Wireless Sensor Networks
Sensors 2015, 15(8), 20373-20391; https://doi.org/10.3390/s150820373
Received: 25 March 2015 / Revised: 21 July 2015 / Accepted: 11 August 2015 / Published: 18 August 2015
Cited by 11 | Viewed by 1898 | PDF Full-text (447 KB) | HTML Full-text | XML Full-text
Abstract
Few techniques for guaranteeing a network lifetime have been proposed despite its great impact on network management. Moreover, since the existing schemes are mostly dependent on the combination of disparate parameters, they do not provide additional services, such as real-time communications and balanced
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Few techniques for guaranteeing a network lifetime have been proposed despite its great impact on network management. Moreover, since the existing schemes are mostly dependent on the combination of disparate parameters, they do not provide additional services, such as real-time communications and balanced energy consumption among sensor nodes; thus, the adaptability problems remain unresolved among nodes in wireless sensor networks (WSNs). To solve these problems, we propose a novel fuzzy logic model to provide real-time communication in a guaranteed WSN lifetime. The proposed fuzzy logic controller accepts the input descriptors energy, time and velocity to determine each node’s role for the next duration and the next hop relay node for real-time packets. Through the simulation results, we verified that both the guaranteed network’s lifetime and real-time delivery are efficiently ensured by the new fuzzy logic model. In more detail, the above-mentioned two performance metrics are improved up to 8%, as compared to our previous work, and 14% compared to existing schemes, respectively. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle Infrastructure-Less Indoor Localization Using the Microphone, Magnetometer and Light Sensor of a Smartphone
Sensors 2015, 15(8), 20355-20372; https://doi.org/10.3390/s150820355
Received: 2 July 2015 / Revised: 7 August 2015 / Accepted: 11 August 2015 / Published: 18 August 2015
Cited by 10 | Viewed by 2363 | PDF Full-text (921 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we present the development of an infrastructure-less indoor location system (ILS), which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available
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In this paper, we present the development of an infrastructure-less indoor location system (ILS), which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available practically in any building in the world, no matter how developed the region is. In our work, we merge the information from those sensors to estimate the user’s location in an indoor environment. A multivariate model is applied to find the user’s location, and we evaluate the quality of the resulting model in terms of sensitivity and specificity. Our experiments were carried out in an office environment during summer and winter, to take into account changes in light patterns, as well as changes in the Earth’s magnetic field irregularities. The experimental results clearly show the benefits of using the information fusion of multiple sensors when contrasted with the use of a single source of information. Full article
(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)
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