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Sensors, Volume 12, Issue 12 (December 2012) , Pages 16008-17632

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Open AccessArticle A Wireless Accelerometer-Based Body Posture Stability Detection System and Its Application for Meditation Practitioners
Sensors 2012, 12(12), 17620-17632; https://doi.org/10.3390/s121217620
Received: 19 October 2012 / Revised: 12 December 2012 / Accepted: 12 December 2012 / Published: 18 December 2012
Cited by 3 | Viewed by 3364 | PDF Full-text (373 KB) | HTML Full-text | XML Full-text
Abstract
The practice of meditation has become an interesting research issue in recent decades. Meditation is known to be beneficial for health improvement and illness reduction and many studies on meditation have been made, from both the physiological and psychological points of view. It [...] Read more.
The practice of meditation has become an interesting research issue in recent decades. Meditation is known to be beneficial for health improvement and illness reduction and many studies on meditation have been made, from both the physiological and psychological points of view. It is a fundamental requirement of meditation practice to be able to sit without body motion. In this study, a novel body motion monitoring and estimation system has been developed. A wireless tri-axis accelerometer is used to measure body motion. Both a mean and maximum motion index is derived from the square summation of three axes. Two experiments were conducted in this study. The first experiment was to investigate the motion index baseline among three leg-crossing postures. The second experiment was to observe posture dynamics for thirty minute’s meditation. Twenty-six subjects participated in the experiments. In one experiment, thirteen subjects were recruited from an experienced meditation group (meditation experience > 3 years); and the other thirteen subjects were beginners (meditation experience < 1 years). There was a significant posture stability difference between both groups in terms of either mean or maximum parameters (p < 0.05), according to the results of the experiment. Results from another experiment showed that the motion index is different for various postures, such as full-lotus < half-lotus < non-lotus. Full article
(This article belongs to the Special Issue Medical & Biological Imaging)
Open AccessArticle Colonization of Potato Rhizosphere by GFP-Tagged Bacillus subtilis MB73/2, Pseudomonas sp. P482 and Ochrobactrum sp. A44 Shown on Large Sections of Roots Using Enrichment Sample Preparation and Confocal Laser Scanning Microscopy
Sensors 2012, 12(12), 17608-17619; https://doi.org/10.3390/s121217608
Received: 30 September 2012 / Revised: 19 November 2012 / Accepted: 21 November 2012 / Published: 18 December 2012
Cited by 17 | Viewed by 4496 | PDF Full-text (3838 KB) | HTML Full-text | XML Full-text
Abstract
The ability to colonize the host plants’ rhizospheres is a crucial feature to study in the case of Plant Growth Promoting Rhizobacteria (PGPRs) with potential agricultural applications. In this work, we have created GFP-tagged derivatives of three candidate PGPRs: Bacillus subtilis MB73/2, Pseudomonas [...] Read more.
The ability to colonize the host plants’ rhizospheres is a crucial feature to study in the case of Plant Growth Promoting Rhizobacteria (PGPRs) with potential agricultural applications. In this work, we have created GFP-tagged derivatives of three candidate PGPRs: Bacillus subtilis MB73/2, Pseudomonas sp. P482 and Ochrobactrum sp. A44. The presence of these strains in the rhizosphere of soil-grown potato (Solanum tuberosum L.) was detected with a classical fluorescence microscope and a confocal laser scanning microscope (CLSM). In this work, we have used a broad-field-of-view CLMS device, dedicated to in vivo analysis of macroscopic objects, equipped with an automated optical zoom system and tunable excitation and detection spectra. We show that features of this type of CLSM microscopes make them particularly well suited to study root colonization by microorganisms. To facilitate the detection of small and scattered bacterial populations, we have developed a fast and user-friendly enrichment method for root sample preparation. The described method, thanks to the in situ formation of mini-colonies, enables visualization of bacterial colonization sites on large root fragments. This approach can be easily modified to study colonization patterns of other fluorescently tagged strains. Additionally, dilution plating of the root extracts was performed to estimate the cell number of MB73/2, P482 and A44 in the rhizosphere of the inoculated plants. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle Simultaneous Monitoring of Soil Water Content and Salinity with a Low-Cost Capacitance-Resistance Probe
Sensors 2012, 12(12), 17588-17607; https://doi.org/10.3390/s121217588
Received: 12 November 2012 / Revised: 13 December 2012 / Accepted: 14 December 2012 / Published: 18 December 2012
Cited by 34 | Viewed by 3781 | PDF Full-text (691 KB) | HTML Full-text | XML Full-text
Abstract
Capacitance and resistivity sensors can be used to continuously monitor soil volumetric water content (θ) and pore-water electrical conductivity (ECp) with non-destructive methods. However, dielectric readings of capacitance sensors operating at low frequencies are normally biased by high [...] Read more.
Capacitance and resistivity sensors can be used to continuously monitor soil volumetric water content (θ) and pore-water electrical conductivity (ECp) with non-destructive methods. However, dielectric readings of capacitance sensors operating at low frequencies are normally biased by high soil electrical conductivity. A procedure to calibrate capacitance-resistance probes in saline conditions was implemented in contrasting soils. A low-cost capacitance-resistance probe (ECH2O-5TE, 70 MHz, Decagon Devices, Pullman, WA, USA) was used in five soils at four water contents (i.e., from dry conditions to saturation) and four salinity levels of the wetting solution (0, 5, 10, and 15 dS·m−1). θ was accurately predicted as a function of the dielectric constant, apparent electrical conductivity (ECa), texture and organic carbon content, even in high salinity conditions. Four models to estimate pore-water electrical conductivity were tested and a set of empirical predicting functions were identified to estimate the model parameters based on easily available soil properties (e.g., texture, soil organic matter). The four models were reformulated to estimate ECp as a function of ECa, dielectric readings, and soil characteristics, improving their performances with respect to the original model formulation. Low-cost capacitance-resistance probes, if properly calibrated, can be effectively used to monitor water and solute dynamics in saline soils. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle Dynamic Propagation Channel Characterization and Modeling for Human Body Communication
Sensors 2012, 12(12), 17569-17587; https://doi.org/10.3390/s121217569
Received: 15 November 2012 / Revised: 12 December 2012 / Accepted: 13 December 2012 / Published: 18 December 2012
Cited by 20 | Viewed by 3288 | PDF Full-text (781 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC). In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand [...] Read more.
This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC). In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000) were acquired from five volunteers. Various path gains caused by different locations and movements were quantified and the statistical distributions were estimated. In general, for a given reference threshold è = −10 dB, the maximum average level crossing rate of the HBC was approximately 1.99 Hz, the maximum average fade time was 59.4 ms, and the percentage of bad channel duration time was less than 4.16%. The HBC exhibited a fade depth of −4 dB at 90% complementary cumulative probability. The statistical parameters were observed to be centered for each propagation channel. Subsequently a Fritchman model was implemented to estimate the burst characteristics of the on-body fading. It was concluded that the HBC is motion-insensitive, which is sufficient for reliable communication link during motions, and therefore it has great potential for body sensor/area networks. Full article
(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)
Open AccessArticle Glyphosate Detection by Means of a Voltammetric Electronic Tongue and Discrimination of Potential Interferents
Sensors 2012, 12(12), 17553-17568; https://doi.org/10.3390/s121217553
Received: 20 September 2012 / Revised: 11 December 2012 / Accepted: 13 December 2012 / Published: 18 December 2012
Cited by 11 | Viewed by 3240 | PDF Full-text (395 KB) | HTML Full-text | XML Full-text
Abstract
A new electronic tongue to monitor the presence of glyphosate (a non-selective systemic herbicide) has been developed. It is based on pulse voltammetry and consists in an array of three working electrodes (Pt, Co and Cu) encapsulated on a methacrylate cylinder. The electrochemical [...] Read more.
A new electronic tongue to monitor the presence of glyphosate (a non-selective systemic herbicide) has been developed. It is based on pulse voltammetry and consists in an array of three working electrodes (Pt, Co and Cu) encapsulated on a methacrylate cylinder. The electrochemical response of the sensing array was characteristic of the presence of glyphosate in buffered water (phosphate buffer 0.1 mol·dm−3, pH 6.7). Rotating disc electrode (RDE) studies were carried out with Pt, Co and Cu electrodes in water at room temperature and at pH 6.7 using 0.1 mol·dm−3 of phosphate as a buffer. In the presence of glyphosate, the corrosion current of the Cu and Co electrodes increased significantly, probably due to the formation of Cu2+ or Co2+ complexes. The pulse array waveform for the voltammetric tongue was designed by taking into account some of the redox processes observed in the electrochemical studies. The PCA statistical analysis required four dimensions to explain 95% of variance. Moreover, a two-dimensional representation of the two principal components differentiated the water mixtures containing glyphosate. Furthermore, the PLS statistical analyses allowed the creation of a model to correlate the electrochemical response of the electrodes with glyphosate concentrations, even in the presence of potential interferents such as humic acids and Ca2+. The system offers a PLS prediction model for glyphosate detection with values of 098, −2.3 × 10−5 and 0.94 for the slope, the intercept and the regression coefficient, respectively, which is in agreement with the good fit between the predicted and measured concentrations. The results suggest the feasibility of this system to help develop electronic tongues for glyphosate detection. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle A Smartphone-Based Driver Safety Monitoring System Using Data Fusion
Sensors 2012, 12(12), 17536-17552; https://doi.org/10.3390/s121217536
Received: 17 October 2012 / Revised: 12 December 2012 / Accepted: 13 December 2012 / Published: 17 December 2012
Cited by 47 | Viewed by 6135 | PDF Full-text (1651 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a method for monitoring driver safety levels using a data fusion approach based on several discrete data types: eye features, bio-signal variation, in-vehicle temperature, and vehicle speed. The driver safety monitoring system was developed in practice in the form of [...] Read more.
This paper proposes a method for monitoring driver safety levels using a data fusion approach based on several discrete data types: eye features, bio-signal variation, in-vehicle temperature, and vehicle speed. The driver safety monitoring system was developed in practice in the form of an application for an Android-based smartphone device, where measuring safety-related data requires no extra monetary expenditure or equipment. Moreover, the system provides high resolution and flexibility. The safety monitoring process involves the fusion of attributes gathered from different sensors, including video, electrocardiography, photoplethysmography, temperature, and a three-axis accelerometer, that are assigned as input variables to an inference analysis framework. A Fuzzy Bayesian framework is designed to indicate the driver’s capability level and is updated continuously in real-time. The sensory data are transmitted via Bluetooth communication to the smartphone device. A fake incoming call warning service alerts the driver if his or her safety level is suspiciously compromised. Realistic testing of the system demonstrates the practical benefits of multiple features and their fusion in providing a more authentic and effective driver safety monitoring. Full article
(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)
Open AccessArticle The Exploitation of Data from Remote and Human Sensors for Environment Monitoring in the SMAT Project
Sensors 2012, 12(12), 17504-17535; https://doi.org/10.3390/s121217504
Received: 21 September 2012 / Revised: 8 December 2012 / Accepted: 10 December 2012 / Published: 17 December 2012
Cited by 10 | Viewed by 3101 | PDF Full-text (7921 KB) | HTML Full-text | XML Full-text
Abstract
The Exploitation of Data from Remote and Human Sensors for Environment Monitoring in the SMAT Project Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)
Open AccessArticle Micro-Displacement Sensor Based on a Hollow-Core Photonic Crystal Fiber
Sensors 2012, 12(12), 17497-17503; https://doi.org/10.3390/s121217497
Received: 15 October 2012 / Revised: 3 December 2012 / Accepted: 12 December 2012 / Published: 17 December 2012
Cited by 16 | Viewed by 3308 | PDF Full-text (341 KB) | HTML Full-text | XML Full-text
Abstract
A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber [...] Read more.
A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber at its other end. A modal interferometer is obtained when the sensing head is close to a mirror, through which displacement is measured. Full article
(This article belongs to the Special Issue Photonic Crystal Sensors)
Open AccessArticle Assisting the Visually Impaired: Obstacle Detection and Warning System by Acoustic Feedback
Sensors 2012, 12(12), 17476-17496; https://doi.org/10.3390/s121217476
Received: 12 October 2012 / Revised: 23 November 2012 / Accepted: 10 December 2012 / Published: 17 December 2012
Cited by 79 | Viewed by 4686 | PDF Full-text (4214 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, [...] Read more.
The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system. Full article
(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)
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Open AccessArticle A New Concept for Quantifying the Complicated Kinematics of the Cervical Spine and Its Application in Evaluating the Impairment of Clients with Mechanical Neck Disorders
Sensors 2012, 12(12), 17463-17475; https://doi.org/10.3390/s121217463
Received: 8 October 2012 / Revised: 7 December 2012 / Accepted: 10 December 2012 / Published: 17 December 2012
Cited by 3 | Viewed by 2963 | PDF Full-text (431 KB) | HTML Full-text | XML Full-text
Abstract
Mechanical neck disorder (MND) is one of the most common health issues and is characterized by restricted cervical mobility. However, traditional kinematic information often focuses on primary movement in the cardinal plane, which seems insufficient to fully determine the kinematics of the cervical [...] Read more.
Mechanical neck disorder (MND) is one of the most common health issues and is characterized by restricted cervical mobility. However, traditional kinematic information often focuses on primary movement in the cardinal plane, which seems insufficient to fully determine the kinematics of the cervical spine because of the complexity of the anatomical structures involved. Therefore, the current investigation aimed to modify the concept of the three-dimensional workspace to propose an objective mathematical model to quantify the complicated kinematics of the cervical spine. In addition, the observation evaluated the characteristics of the cervical workspace in asymptomatic and MND groups. Seventeen healthy volunteers and twenty-five individuals with MND participated in the study and executed the motion of circumduction to establish the cervical workspace using an electromagnetic tracking system. The results produced a mathematical model to successfully quantify the cervical workspace. Moreover, MND groups demonstrated significant reduction in the normalization of the cervical workspace with respect to the length of the head-cervical complex. Accordingly, the current study provided a new concept for understanding the complicated kinematics of the cervical spine. The cervical workspace could be a useful index to evaluate the extent of impairment of the cervical spine and monitor the efficacy of rehabilitation programs for patients with MND. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessEditorial Paper Withdrawn by the Authors before the Issue Release
Sensors 2012, 12(12), 16250-16261; https://doi.org/10.3390/s121216250
Received: 17 December 2012 / Accepted: 17 December 2012 / Published: 17 December 2012
PDF Full-text (99 KB) | HTML Full-text | XML Full-text
Abstract
The following paper: “Jung, S.; Kim, J.H.; Kim, S. Bloom Filter-Based Advanced Traceback Scheme in Wireless Sensor Networks. Sensors 2012, 12, 16250-16261.” has been withdrawn at the request of the authors before the issue release of Sensors Volume 12, Issue 12. We apologize [...] Read more.
The following paper: “Jung, S.; Kim, J.H.; Kim, S. Bloom Filter-Based Advanced Traceback Scheme in Wireless Sensor Networks. Sensors 2012, 12, 16250-16261.” has been withdrawn at the request of the authors before the issue release of Sensors Volume 12, Issue 12. We apologize for any inconvenience this may cause. [...] Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
Open AccessArticle A Mobile Asset Tracking System Architecture under Mobile-Stationary Co-Existing WSNs
Sensors 2012, 12(12), 17446-17462; https://doi.org/10.3390/s121217446
Received: 22 October 2012 / Revised: 22 November 2012 / Accepted: 12 December 2012 / Published: 14 December 2012
Cited by 8 | Viewed by 4993 | PDF Full-text (1033 KB) | HTML Full-text | XML Full-text
Abstract
The tracking of multiple wireless mobile nodes is not easy with current legacy WSN technologies, due to their inherent technical complexity, especially when heavy traffic and frequent movement of mobile nodes are encountered. To enable mobile asset tracking under these legacy WSN systems, [...] Read more.
The tracking of multiple wireless mobile nodes is not easy with current legacy WSN technologies, due to their inherent technical complexity, especially when heavy traffic and frequent movement of mobile nodes are encountered. To enable mobile asset tracking under these legacy WSN systems, it is necessary to design a specific system architecture that can manage numerous mobile nodes attached to mobile assets. In this paper, we present a practical system architecture including a communication protocol, a three-tier network, and server-side middleware for mobile asset tracking in legacy WSNs consisting of mobile-stationary co-existing infrastructures, and we prove the functionality of this architecture through careful evaluation in a test bed. Evaluation was carried out in a microwave anechoic chamber as well as on a straight road near our office. We evaluated communication mobility performance between mobile and stationary nodes, location-awareness performance, system stability under numerous mobile node conditions, and the successful packet transfer rate according to the speed of the mobile nodes. The results indicate that the proposed architecture is sufficiently robust for application in realistic mobile asset tracking services that require a large number of mobile nodes. Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
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Open AccessArticle Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation
Sensors 2012, 12(12), 17433-17445; https://doi.org/10.3390/s121217433
Received: 17 October 2012 / Revised: 27 November 2012 / Accepted: 27 November 2012 / Published: 14 December 2012
Cited by 15 | Viewed by 3150 | PDF Full-text (816 KB) | HTML Full-text | XML Full-text
Abstract
Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current [...] Read more.
Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Electrochemical Genotoxicity Assay Based on a SOS/umu Test Using Hydrodynamic Voltammetry in a Droplet
Sensors 2012, 12(12), 17414-17432; https://doi.org/10.3390/s121217414
Received: 17 September 2012 / Revised: 10 December 2012 / Accepted: 12 December 2012 / Published: 14 December 2012
Cited by 9 | Viewed by 3606 | PDF Full-text (612 KB) | HTML Full-text | XML Full-text
Abstract
The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples [...] Read more.
The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids. However, umu tests with electrochemical detection techniques prove to be a better strategy because it causes less interference, enables the analysis of turbid samples and allows detection even in small volumes without loss of sensitivity. Based on this understanding, we aim to develop a new umu test system with hydrodynamic chronoamperometry using a rotating disk electrode (RDE) in a microliter droplet. PAPG when used as a substrate is not electroactive at the potential at which PAP is oxidized to p-quinone imine (PQI), so the current response of chronoamperometry resulting from the oxidation of PAP to PQI is directly proportional to the enzymatic activity of S. typhimurium. This was achieved by performing genotoxicity tests for 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and 2-aminoanthracene (2-AA) as model genotoxic compounds. The results obtained in this study indicated that the signal detection in the genotoxicity assay based on hydrodynamic voltammetry was less influenced by the presence of colored components and sediment particles in the samples when compared to the usual colorimetric signal detection. The influence caused by the presence of humic acids (HAs) and artificial sediment on the genotoxic property of selected model compounds such as 4-nitroquinoline-N-oxide (4-NQO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 1,8-dinitropyrene (1,8-DNP) and 1-nitropyrene (1-NP) were also investigated. The results showed that the genotoxicity of 1-NP and MX changed in the presence of 10 mg∙L–1 HAs. The genotoxicity of tested chemicals with a high hydrophobicity such as 1,8-DNP and 1-NP were decreased substantially with the presence of 1 g∙L–1 sediment. This was not observed in the case of genotoxins with a low log Kow value. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle A Comparison of Error Bounds for a Nonlinear Tracking System with Detection Probability Pd < 1
Sensors 2012, 12(12), 17390-17413; https://doi.org/10.3390/s121217390
Received: 8 October 2012 / Revised: 6 December 2012 / Accepted: 7 December 2012 / Published: 14 December 2012
Cited by 1 | Viewed by 2369 | PDF Full-text (881 KB) | HTML Full-text | XML Full-text
Abstract
Error bounds for nonlinear filtering are very important for performance evaluation and sensor management. This paper presents a comparative study of three error bounds for tracking filtering, when the detection probability is less than unity. One of these bounds is the random finite [...] Read more.
Error bounds for nonlinear filtering are very important for performance evaluation and sensor management. This paper presents a comparative study of three error bounds for tracking filtering, when the detection probability is less than unity. One of these bounds is the random finite set (RFS) bound, which is deduced within the framework of finite set statistics. The others, which are the information reduction factor (IRF) posterior Cramer-Rao lower bound (PCRLB) and enumeration method (ENUM) PCRLB are introduced within the framework of finite vector statistics. In this paper, we deduce two propositions and prove that the RFS bound is equal to the ENUM PCRLB, while it is tighter than the IRF PCRLB, when the target exists from the beginning to the end. Considering the disappearance of existing targets and the appearance of new targets, the RFS bound is tighter than both IRF PCRLB and ENUM PCRLB with time, by introducing the uncertainty of target existence. The theory is illustrated by two nonlinear tracking applications: ballistic object tracking and bearings-only tracking. The simulation studies confirm the theory and reveal the relationship among the three bounds. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle On-Line Smoothing for an Integrated Navigation System with Low-Cost MEMS Inertial Sensors
Sensors 2012, 12(12), 17372-17389; https://doi.org/10.3390/s121217372
Received: 17 October 2012 / Revised: 6 December 2012 / Accepted: 7 December 2012 / Published: 13 December 2012
Cited by 25 | Viewed by 3472 | PDF Full-text (1241 KB) | HTML Full-text | XML Full-text
Abstract
The integration of the Inertial Navigation System (INS) and the Global Positioning System (GPS) is widely applied to seamlessly determine the time-variable position and orientation parameters of a system for navigation and mobile mapping applications. For optimal data fusion, the Kalman filter (KF) [...] Read more.
The integration of the Inertial Navigation System (INS) and the Global Positioning System (GPS) is widely applied to seamlessly determine the time-variable position and orientation parameters of a system for navigation and mobile mapping applications. For optimal data fusion, the Kalman filter (KF) is often used for real-time applications. Backward smoothing is considered an optimal post-processing procedure. However, in current INS/GPS integration schemes, the KF and smoothing techniques still have some limitations. This article reviews the principles and analyzes the limitations of these estimators. In addition, an on-line smoothing method that overcomes the limitations of previous algorithms is proposed. For verification, an INS/GPS integrated architecture is implemented using a low-cost micro-electro-mechanical systems inertial measurement unit and a single-frequency GPS receiver. GPS signal outages are included in the testing trajectories to evaluate the effectiveness of the proposed method in comparison to conventional schemes. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle A Laboratory Goniometer System for Measuring Reflectance and Emittance Anisotropy
Sensors 2012, 12(12), 17358-17371; https://doi.org/10.3390/s121217358
Received: 19 September 2012 / Revised: 7 December 2012 / Accepted: 11 December 2012 / Published: 13 December 2012
Cited by 14 | Viewed by 4005 | PDF Full-text (659 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much [...] Read more.
In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers. Full article
(This article belongs to the Special Issue Workshop Sensing A Changing World 2012)
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Open AccessArticle An Ultrasonic System for Weed Detection in Cereal Crops
Sensors 2012, 12(12), 17343-17357; https://doi.org/10.3390/s121217343
Received: 22 October 2012 / Revised: 2 December 2012 / Accepted: 10 December 2012 / Published: 13 December 2012
Cited by 28 | Viewed by 4053 | PDF Full-text (12122 KB) | HTML Full-text | XML Full-text
Abstract
Site-specific weed management requires sensing of the actual weed infestation levels in agricultural fields to adapt the management accordingly. However, sophisticated sensor systems are not yet in wider practical use, since they are not easily available for the farmers and their handling as [...] Read more.
Site-specific weed management requires sensing of the actual weed infestation levels in agricultural fields to adapt the management accordingly. However, sophisticated sensor systems are not yet in wider practical use, since they are not easily available for the farmers and their handling as well as the management practice requires additional efforts. A new sensor-based weed detection method is presented in this paper and its applicability to cereal crops is evaluated. An ultrasonic distance sensor for the determination of plant heights was used for weed detection. It was hypothesised that the weed infested zones have a higher amount of biomass than non-infested areas and that this can be determined by plant height measurements. Ultrasonic distance measurements were taken in a winter wheat field infested by grass weeds and broad-leaved weeds. A total of 80 and 40 circular-shaped samples of different weed densities and compositions were assessed at two different dates. The sensor was pointed directly to the ground for height determination. In the following, weeds were counted and then removed from the sample locations. Grass weeds and broad-leaved weeds were separately removed. Differences between weed infested and weed-free measurements were determined. Dry-matter of weeds and crop was assessed and evaluated together with the sensor measurements. RGB images were taken prior and after weed removal to determine the coverage percentages of weeds and crop per sampling point. Image processing steps included EGI (excess green index) computation and thresholding to separate plants and background. The relationship between ultrasonic readings and the corresponding coverage of the crop and weeds were assessed using multiple regression analysis. Results revealed a height difference between infested and non-infested sample locations. Density and biomass of weeds present in the sample influenced the ultrasonic readings. The possibilities of weed group discrimination were assessed by discriminant analysis. The ultrasonic readings permitted the separation between weed infested zones and non-infested areas with up to 92.8% of success. This system will potentially reduce the cost of weed detection and offers an opportunity to its use in non-selective methods for weed control. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle Optical Waveguide Lightmode Spectroscopy (OWLS) as a Sensor for Thin Film and Quantum Dot Corrosion
Sensors 2012, 12(12), 17330-17342; https://doi.org/10.3390/s121217330
Received: 5 October 2012 / Revised: 16 November 2012 / Accepted: 30 November 2012 / Published: 13 December 2012
Cited by 5 | Viewed by 4048 | PDF Full-text (1220 KB) | HTML Full-text | XML Full-text
Abstract
Optical waveguide lightmode spectroscopy (OWLS) is usually applied as a biosensor system to the sorption-desorption of proteins to waveguide surfaces. Here, we show that OWLS can be used to monitor the quality of oxide thin film materials and of coatings of pulsed laser [...] Read more.
Optical waveguide lightmode spectroscopy (OWLS) is usually applied as a biosensor system to the sorption-desorption of proteins to waveguide surfaces. Here, we show that OWLS can be used to monitor the quality of oxide thin film materials and of coatings of pulsed laser deposition synthesized CdSe quantum dots (QDs) intended for solar energy applications. In addition to changes in data treatment and experimental procedure, oxide- or QD-coated waveguide sensors must be synthesized. We synthesized zinc stannate (Zn2SnO4) coated (Si,Ti)O2 waveguide sensors, and used OWLS to monitor the relative mass of the film over time. Films lost mass over time, though at different rates due to variation in fluid flow and its physical effect on removal of film material. The Pulsed Laser Deposition (PLD) technique was used to deposit CdSe QD coatings on waveguides. Sensors exposed to pH 2 solution lost mass over time in an expected, roughly exponential manner. Sensors at pH 10, in contrast, were stable over time. Results were confirmed with atomic force microscopy imaging. Limiting factors in the use of OWLS in this manner include limitations on the annealing temperature that maybe used to synthesize the oxide film, and limitations on the thickness of the film to be studied. Nevertheless, the technique overcomes a number of difficulties in monitoring the quality of thin films in-situ in liquid environments. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessCommunication An Ultrasensitive Chemiluminescence Biosensor for Carcinoembryonic Antigen Based on Autocatalytic Enlargement of Immunogold Nanoprobes
Sensors 2012, 12(12), 17320-17329; https://doi.org/10.3390/s121217320
Received: 19 October 2012 / Revised: 27 November 2012 / Accepted: 5 December 2012 / Published: 13 December 2012
Cited by 7 | Viewed by 3818 | PDF Full-text (267 KB) | HTML Full-text | XML Full-text
Abstract
A sensitive flow injection chemiluminescence assay for carcinoembryonic antigen (CEA) detection based on signal amplification with gold nanoparticles (NPs) is reported in the present work. The sandwich system of CEA/anti-CEA/goat-anti-mouse IgG functionalized Au nanoparticles was used as the sensing platform. In order to [...] Read more.
A sensitive flow injection chemiluminescence assay for carcinoembryonic antigen (CEA) detection based on signal amplification with gold nanoparticles (NPs) is reported in the present work. The sandwich system of CEA/anti-CEA/goat-anti-mouse IgG functionalized Au nanoparticles was used as the sensing platform. In order to improve detection sensitivity, a further gold enlargement step was developed based on the autocatalytic Au deposition of gold nanoprobes via the reduction of AuCl4 to Au0 on their surface in the presence of NH2OH·HCl. AuCl4, which is a soluble product of gold nanoprobes, served as an analyte in the CL reaction for the indirect measurement of CEA. Under optimized conditions, the CL intensity of the system was linearly related to the logarithm of CEA concentration in the range of 100 pg∙mL−1 to 1,000 ng∙mL−1, with a detection limit of 20 pg∙mL−1. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Towards a Hybrid Energy Efficient Multi-Tree-Based Optimized Routing Protocol for Wireless Networks
Sensors 2012, 12(12), 17295-17319; https://doi.org/10.3390/s121217295
Received: 24 October 2012 / Revised: 10 December 2012 / Accepted: 12 December 2012 / Published: 13 December 2012
Cited by 5 | Viewed by 2703 | PDF Full-text (795 KB) | HTML Full-text | XML Full-text
Abstract
This paper considers the problem of designing power efficient routing with guaranteed delivery for sensor networks with unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on [...] Read more.
This paper considers the problem of designing power efficient routing with guaranteed delivery for sensor networks with unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In HECTOR, the node currently holding the packet forwards it to its neighbor that optimizes ratio of power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase distance in tree coordinates. If such a node does not exist, then forwarding is made to the neighbor that reduces tree-based distance only and optimizes power cost over tree distance progress ratio. We theoretically prove the packet delivery and propose an extension based on the use of multiple trees. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30% additional power compared to centralized shortest weighted path algorithm. Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
Open AccessArticle Label-Free Microcavity Biosensors: Steps towards Personalized Medicine
Sensors 2012, 12(12), 17262-17294; https://doi.org/10.3390/s121217262
Received: 16 November 2012 / Revised: 10 December 2012 / Accepted: 11 December 2012 / Published: 13 December 2012
Cited by 2 | Viewed by 3236 | PDF Full-text (1074 KB) | HTML Full-text | XML Full-text
Abstract
Personalized medicine has the potential to improve our ability to maintain health and treat disease, while ameliorating continuously rising healthcare costs. Translation of basic research findings to clinical applications within regulatory compliance is required for personalized medicine to become the new foundation for [...] Read more.
Personalized medicine has the potential to improve our ability to maintain health and treat disease, while ameliorating continuously rising healthcare costs. Translation of basic research findings to clinical applications within regulatory compliance is required for personalized medicine to become the new foundation for practice of medicine. Deploying even a few of the thousands of potential diagnostic biomarkers identified each year as part of personalized treatment workflows requires clinically efficient biosensor technologies to monitor multiple biomarkers in patients in real time. This paper discusses a critical component of a regulatory system, a microcavity optical biosensor for label-free monitoring of biomolecular interactions at physiologically-relevant concentrations. While most current biosensor research focuses on improving sensitivity, this paper emphasizes other characteristics a biosensor technology requires to be practical in a clinical setting, presenting robust microcavity biosensors which are easy to manufacture and integrate with microfluidics into flexible and redesignable platforms making the microcavity biosensors deployable for continuous monitoring of biomarkers in body fluids in the clinic, in dense 2D random arrays for high-throughput applications like drug-library screening in interactomics, and of the secretory behavior of single cells in the laboratory. Full article
(This article belongs to the Special Issue Ultra-Small Sensor Systems and Components)
Open AccessArticle An Amperometric Immunosensor Based on Multi-Walled Carbon Nanotubes-Thionine-Chitosan Nanocomposite Film for Chlorpyrifos Detection
Sensors 2012, 12(12), 17247-17261; https://doi.org/10.3390/s121217247
Received: 19 October 2012 / Revised: 10 December 2012 / Accepted: 11 December 2012 / Published: 13 December 2012
Cited by 30 | Viewed by 3275 | PDF Full-text (980 KB) | HTML Full-text | XML Full-text
Abstract
In this work, a novel amperometric immunosensor based on multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film as electrode modified material was developed for the detection of chlorpyrifos residues. The nanocomposite film was dropped onto a glassy carbon electrode (GCE), and then the anti-chlorpyrifos monoclonal [...] Read more.
In this work, a novel amperometric immunosensor based on multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film as electrode modified material was developed for the detection of chlorpyrifos residues. The nanocomposite film was dropped onto a glassy carbon electrode (GCE), and then the anti-chlorpyrifos monoclonal antibody was covalently immobilized onto the surface of MWCNTs-THI-CHIT/GCE using the crosslinking agent glutaraldehyde (GA). The modification procedure was characterized by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the relative change in peak current of different pulse voltammetry (DPV) and the logarithm of chlorpyrifos solution concentration was obtained in the range from 0.1 to 1.0 × 105 ng/mL with a detection limit of 0.046 ng/mL. The proposed chlorpyrifos immunosensor exhibited high reproducibility, stability, and good selectivity and regeneration, making it a potential alternative tool for ultrasensitive detection of chlorpyrifos residues in vegetables and fruits. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Application of Hyperspectral Imaging and Chemometric Calibrations for Variety Discrimination of Maize Seeds
Sensors 2012, 12(12), 17234-17246; https://doi.org/10.3390/s121217234
Received: 12 October 2012 / Revised: 27 November 2012 / Accepted: 10 December 2012 / Published: 12 December 2012
Cited by 73 | Viewed by 4006 | PDF Full-text (597 KB) | HTML Full-text | XML Full-text
Abstract
Hyperspectral imaging in the visible and near infrared (VIS-NIR) region was used to develop a novel method for discriminating different varieties of commodity maize seeds. Firstly, hyperspectral images of 330 samples of six varieties of maize seeds were acquired using a hyperspectral imaging [...] Read more.
Hyperspectral imaging in the visible and near infrared (VIS-NIR) region was used to develop a novel method for discriminating different varieties of commodity maize seeds. Firstly, hyperspectral images of 330 samples of six varieties of maize seeds were acquired using a hyperspectral imaging system in the 380–1,030 nm wavelength range. Secondly, principal component analysis (PCA) and kernel principal component analysis (KPCA) were used to explore the internal structure of the spectral data. Thirdly, three optimal wavelengths (523, 579 and 863 nm) were selected by implementing PCA directly on each image. Then four textural variables including contrast, homogeneity, energy and correlation were extracted from gray level co-occurrence matrix (GLCM) of each monochromatic image based on the optimal wavelengths. Finally, several models for maize seeds identification were established by least squares-support vector machine (LS-SVM) and back propagation neural network (BPNN) using four different combinations of principal components (PCs), kernel principal components (KPCs) and textural features as input variables, respectively. The recognition accuracy achieved in the PCA-GLCM-LS-SVM model (98.89%) was the most satisfactory one. We conclude that hyperspectral imaging combined with texture analysis can be implemented for fast classification of different varieties of maize seeds. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle A Hybrid Smartphone Indoor Positioning Solution for Mobile LBS
Sensors 2012, 12(12), 17208-17233; https://doi.org/10.3390/s121217208
Received: 29 October 2012 / Revised: 6 December 2012 / Accepted: 7 December 2012 / Published: 12 December 2012
Cited by 92 | Viewed by 6801 | PDF Full-text (1136 KB) | HTML Full-text | XML Full-text
Abstract
Smartphone positioning is an enabling technology used to create new business in the navigation and mobile location-based services (LBS) industries. This paper presents a smartphone indoor positioning engine named HIPE that can be easily integrated with mobile LBS. HIPE is a hybrid solution [...] Read more.
Smartphone positioning is an enabling technology used to create new business in the navigation and mobile location-based services (LBS) industries. This paper presents a smartphone indoor positioning engine named HIPE that can be easily integrated with mobile LBS. HIPE is a hybrid solution that fuses measurements of smartphone sensors with wireless signals. The smartphone sensors are used to measure the user’s motion dynamics information (MDI), which represent the spatial correlation of various locations. Two algorithms based on hidden Markov model (HMM) problems, the grid-based filter and the Viterbi algorithm, are used in this paper as the central processor for data fusion to resolve the position estimates, and these algorithms are applicable for different applications, e.g., real-time navigation and location tracking, respectively. HIPE is more widely applicable for various motion scenarios than solutions proposed in previous studies because it uses no deterministic motion models, which have been commonly used in previous works. The experimental results showed that HIPE can provide adequate positioning accuracy and robustness for different scenarios of MDI combinations. HIPE is a cost-efficient solution, and it can work flexibly with different smartphone platforms, which may have different types of sensors available for the measurement of MDI data. The reliability of the positioning solution was found to increase with increasing precision of the MDI data. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle Intuitive Terrain Reconstruction Using Height Observation-Based Ground Segmentation and 3D Object Boundary Estimation
Sensors 2012, 12(12), 17186-17207; https://doi.org/10.3390/s121217186
Received: 8 October 2012 / Revised: 7 December 2012 / Accepted: 11 December 2012 / Published: 12 December 2012
Cited by 13 | Viewed by 3332 | PDF Full-text (1336 KB) | HTML Full-text | XML Full-text
Abstract
Mobile robot operators must make rapid decisions based on information about the robot’s surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the [...] Read more.
Mobile robot operators must make rapid decisions based on information about the robot’s surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot’s array of sensors, but some upper parts of objects are beyond the sensors’ measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. Full article
(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)
Open AccessArticle PSO Algorithm Particle Filters for Improving the Performance of Lane Detection and Tracking Systems in Difficult Roads
Sensors 2012, 12(12), 17168-17185; https://doi.org/10.3390/s121217168
Received: 9 August 2012 / Revised: 7 December 2012 / Accepted: 10 December 2012 / Published: 12 December 2012
Cited by 11 | Viewed by 2945 | PDF Full-text (405 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we propose a robust lane detection and tracking method by combining particle filters with the particle swarm optimization method. This method mainly uses the particle filters to detect and track the local optimum of the lane model in the input [...] Read more.
In this paper we propose a robust lane detection and tracking method by combining particle filters with the particle swarm optimization method. This method mainly uses the particle filters to detect and track the local optimum of the lane model in the input image and then seeks the global optimal solution of the lane model by a particle swarm optimization method. The particle filter can effectively complete lane detection and tracking in complicated or variable lane environments. However, the result obtained is usually a local optimal system status rather than the global optimal system status. Thus, the particle swarm optimization method is used to further refine the global optimal system status in all system statuses. Since the particle swarm optimization method is a global optimization algorithm based on iterative computing, it can find the global optimal lane model by simulating the food finding way of fish school or insects under the mutual cooperation of all particles. In verification testing, the test environments included highways and ordinary roads as well as straight and curved lanes, uphill and downhill lanes, lane changes, etc. Our proposed method can complete the lane detection and tracking more accurately and effectively then existing options. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Effects of Cry1Ab Transgenic Maize on Lifecycle and Biomarker Responses of the Earthworm, Eisenia Andrei
Sensors 2012, 12(12), 17155-17167; https://doi.org/10.3390/s121217155
Received: 16 September 2012 / Revised: 14 November 2012 / Accepted: 30 November 2012 / Published: 12 December 2012
Cited by 7 | Viewed by 2751 | PDF Full-text (276 KB) | HTML Full-text | XML Full-text
Abstract
A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this [...] Read more.
A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT) and potential genotoxic effects in terms of Randomly Amplified Polymorphic DNA sequences (RAPDs). NRRT results indicated no differences between treatments (p > 0.36), and NRRT remained the same for both treatments at different times during the experiment (p = 0.18). Likewise, no significant differences were found for cocoon production (p = 0.32) or hatching success (p = 0.29). Conversely, biomass data indicated a significant difference between the control treatment and the Bt treatment from the second week onwards (p < 0.001), with the Bt treatment losing significantly more weight than the isoline treatment. Possible confounding factors were identified that might have affected the differences in weight loss between groups. From the RAPD profiles no conclusive data were obtained that could link observed genetic variation to exposure of E. andrei to Cry1Ab proteins produced by Bt maize. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle Prioritized Degree Distribution in Wireless Sensor Networks with a Network Coded Data Collection Method
Sensors 2012, 12(12), 17128-17154; https://doi.org/10.3390/s121217128
Received: 3 October 2012 / Revised: 29 November 2012 / Accepted: 3 December 2012 / Published: 12 December 2012
Cited by 2 | Viewed by 3003 | PDF Full-text (450 KB) | HTML Full-text | XML Full-text
Abstract
The reliability of wireless sensor networks (WSNs) can be greatly affected by failures of sensor nodes due to energy exhaustion or the influence of brutal external environment conditions. Such failures seriously affect the data persistence and collection efficiency. Strategies based on network coding [...] Read more.
The reliability of wireless sensor networks (WSNs) can be greatly affected by failures of sensor nodes due to energy exhaustion or the influence of brutal external environment conditions. Such failures seriously affect the data persistence and collection efficiency. Strategies based on network coding technology for WSNs such as LTCDS can improve the data persistence without mass redundancy. However, due to the bad intermediate performance of LTCDS, a serious ‘cliff effect’ may appear during the decoding period, and source data are hard to recover from sink nodes before sufficient encoded packets are collected. In this paper, the influence of coding degree distribution strategy on the ‘cliff effect’ is observed and the prioritized data storage and dissemination algorithm PLTD-ALPHA is presented to achieve better data persistence and recovering performance. With PLTD-ALPHA, the data in sensor network nodes present a trend that their degree distribution increases along with the degree level predefined, and the persistent data packets can be submitted to the sink node according to its degree in order. Finally, the performance of PLTD-ALPHA is evaluated and experiment results show that PLTD-ALPHA can greatly improve the data collection performance and decoding efficiency, while data persistence is not notably affected. Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
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Open AccessArticle Prototypes of Newly Conceived Inorganic and Biological Sensors for Health and Environmental Applications
Sensors 2012, 12(12), 17112-17127; https://doi.org/10.3390/s121217112
Received: 8 October 2012 / Revised: 7 December 2012 / Accepted: 11 December 2012 / Published: 12 December 2012
Cited by 19 | Viewed by 3123 | PDF Full-text (417 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the optimal implementation of three newly conceived sensors for both health and environmental applications, utilizing a wide range of detection methods and complex nanocomposites. The first one is inorganic and based on matrices of calcium oxide, the second is based [...] Read more.
This paper describes the optimal implementation of three newly conceived sensors for both health and environmental applications, utilizing a wide range of detection methods and complex nanocomposites. The first one is inorganic and based on matrices of calcium oxide, the second is based on protein arrays and a third one is based on Langmuir-Blodgett laccase multi-layers. Special attention was paid to detecting substances significant to the environment (such as carbon dioxide) and medicine (drug administration, cancer diagnosis and prognosis) by means of amperometric, quartz crystal microbalance with frequency (QCM_F) and quartz crystal microbalance with dissipation monitoring (QCM_D) technologies. The resulting three implemented nanosensors are described here along with proofs of principle and their corresponding applications. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)
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