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Sensors, Volume 13, Issue 2 (February 2013) , Pages 1385-2699

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Open AccessArticle A Unified Framework for Activity Recognition-Based Behavior Analysis and Action Prediction in Smart Homes
Sensors 2013, 13(2), 2682-2699; https://doi.org/10.3390/s130202682
Received: 16 December 2012 / Revised: 12 February 2013 / Accepted: 15 February 2013 / Published: 22 February 2013
Cited by 28 | Viewed by 3622 | PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, activity recognition in smart homes is an active research area due to its applicability in many applications, such as assistive living and healthcare. Besides activity recognition, the information collected from smart homes has great potential for other application domains like [...] Read more.
In recent years, activity recognition in smart homes is an active research area due to its applicability in many applications, such as assistive living and healthcare. Besides activity recognition, the information collected from smart homes has great potential for other application domains like lifestyle analysis, security and surveillance, and interaction monitoring. Therefore, discovery of users common behaviors and prediction of future actions from past behaviors become an important step towards allowing an environment to provide personalized service. In this paper, we develop a unified framework for activity recognition-based behavior analysis and action prediction. For this purpose, first we propose kernel fusion method for accurate activity recognition and then identify the significant sequential behaviors of inhabitants from recognized activities of their daily routines. Moreover, behaviors patterns are further utilized to predict the future actions from past activities. To evaluate the proposed framework, we performed experiments on two real datasets. The results show a remarkable improvement of 13.82% in the accuracy on average of recognized activities along with the extraction of significant behavioral patterns and precise activity predictions with 6.76% increase in F-measure. All this collectively help in understanding the users” actions to gain knowledge about their habits and preferences. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle An Incremental Target-Adapted Strategy for Active Geometric Calibration of Projector-Camera Systems
Sensors 2013, 13(2), 2664-2681; https://doi.org/10.3390/s130202664
Received: 11 January 2013 / Revised: 11 February 2013 / Accepted: 15 February 2013 / Published: 22 February 2013
Cited by 14 | Viewed by 3814 | PDF Full-text (2169 KB) | HTML Full-text | XML Full-text
Abstract
The calibration of a projector-camera system is an essential step toward accurate 3-D measurement and environment-aware data projection applications, such as augmented reality. In this paper we present a two-stage easy-to-deploy strategy for robust calibration of both intrinsic and extrinsic parameters of a [...] Read more.
The calibration of a projector-camera system is an essential step toward accurate 3-D measurement and environment-aware data projection applications, such as augmented reality. In this paper we present a two-stage easy-to-deploy strategy for robust calibration of both intrinsic and extrinsic parameters of a projector. Two key components of the system are the automatic generation of projected light patterns and the incremental calibration process. Based on the incremental strategy, the calibration process first establishes a set of initial parameters, and then it upgrades these parameters incrementally using the projection and captured images of dynamically-generated calibration patterns. The scene-driven light patterns allow the system to adapt itself to the pose of the calibration target, such that the difficulty in feature detection is greatly lowered. The strategy forms a closed-loop system that performs self-correction as more and more observations become available. Compared to the conventional method, which requires a time-consuming process for the acquisition of dense pixel correspondences, the proposed method deploys a homography-based coordinate computation, allowing the calibration time to be dramatically reduced. The experimental results indicate that an improvement of 70% in reprojection errors is achievable and 95% of the calibration time can be saved. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Autonomous Docking Based on Infrared System for Electric Vehicle Charging in Urban Areas
Sensors 2013, 13(2), 2645-2663; https://doi.org/10.3390/s130202645
Received: 11 December 2012 / Revised: 24 January 2013 / Accepted: 5 February 2013 / Published: 21 February 2013
Cited by 12 | Viewed by 4334 | PDF Full-text (1283 KB) | HTML Full-text | XML Full-text
Abstract
Electric vehicles are progressively introduced in urban areas, because of their ability to reduce air pollution, fuel consumption and noise nuisance. Nowadays, some big cities are launching the first electric car-sharing projects to clear traffic jams and enhance urban mobility, as an alternative [...] Read more.
Electric vehicles are progressively introduced in urban areas, because of their ability to reduce air pollution, fuel consumption and noise nuisance. Nowadays, some big cities are launching the first electric car-sharing projects to clear traffic jams and enhance urban mobility, as an alternative to the classic public transportation systems. However, there are still some problems to be solved related to energy storage, electric charging and autonomy. In this paper, we present an autonomous docking system for electric vehicles recharging based on an embarked infrared camera performing infrared beacons detection installed in the infrastructure. A visual servoing system coupled with an automatic controller allows the vehicle to dock accurately to the recharging booth in a street parking area. The results show good behavior of the implemented system, which is currently deployed as a real prototype system in the city of Paris. Full article
(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)
Open AccessArticle On the Effects of the Lateral Strains on the Fiber Bragg Grating Response
Sensors 2013, 13(2), 2631-2644; https://doi.org/10.3390/s130202631
Received: 6 December 2012 / Revised: 6 February 2013 / Accepted: 13 February 2013 / Published: 21 February 2013
Cited by 19 | Viewed by 4049 | PDF Full-text (822 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with [...] Read more.
In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with no constrains on planes normal to the embedded sensor’s axis is biaxially loaded, (b) when the same isotropic host material is subjected to hydrostatic pressure and (c) when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite. Full article
(This article belongs to the Special Issue Laser Sensing and Imaging)
Open AccessArticle A Neuro-Fuzzy System for Characterization of Arm Movements
Sensors 2013, 13(2), 2613-2630; https://doi.org/10.3390/s130202613
Received: 13 December 2012 / Revised: 15 February 2013 / Accepted: 16 February 2013 / Published: 21 February 2013
Cited by 16 | Viewed by 3028 | PDF Full-text (705 KB) | HTML Full-text | XML Full-text
Abstract
The myoelectric signal reflects the electrical activity of skeletal muscles and contains information about the structure and function of the muscles which make different parts of the body move. Advances in engineering have extended electromyography beyond the traditional diagnostic applications to also include [...] Read more.
The myoelectric signal reflects the electrical activity of skeletal muscles and contains information about the structure and function of the muscles which make different parts of the body move. Advances in engineering have extended electromyography beyond the traditional diagnostic applications to also include applications in diverse areas such as rehabilitation, movement analysis and myoelectric control of prosthesis. This paper aims to study and develop a system that uses myoelectric signals, acquired by surface electrodes, to characterize certain movements of the human arm. To recognize certain hand-arm segment movements, was developed an algorithm for pattern recognition technique based on neuro-fuzzy, representing the core of this research. This algorithm has as input the preprocessed myoelectric signal, to disclosed specific characteristics of the signal, and as output the performed movement. The average accuracy obtained was 86% to 7 distinct movements in tests of long duration (about three hours). Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Virtual and Remote Robotic Laboratory Using EJS, MATLAB and LabVIEW
Sensors 2013, 13(2), 2595-2612; https://doi.org/10.3390/s130202595
Received: 28 December 2012 / Revised: 1 February 2013 / Accepted: 16 February 2013 / Published: 21 February 2013
Cited by 43 | Viewed by 5237 | PDF Full-text (1289 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the design and implementation of a virtual and remote laboratory based on Easy Java Simulations (EJS) and LabVIEW. The main application of this laboratory is to improve the study of sensors in Mobile Robotics, dealing with the problems that arise [...] Read more.
This paper describes the design and implementation of a virtual and remote laboratory based on Easy Java Simulations (EJS) and LabVIEW. The main application of this laboratory is to improve the study of sensors in Mobile Robotics, dealing with the problems that arise on the real world experiments. This laboratory allows the user to work from their homes, tele-operating a real robot that takes measurements from its sensors in order to obtain a map of its environment. In addition, the application allows interacting with a robot simulation (virtual laboratory) or with a real robot (remote laboratory), with the same simple and intuitive graphical user interface in EJS. Thus, students can develop signal processing and control algorithms for the robot in simulation and then deploy them on the real robot for testing purposes. Practical examples of application of the laboratory on the inter-University Master of Systems Engineering and Automatic Control are presented. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Wedge-Filtering of Geomorphologic Terrestrial Laser Scan Data
Sensors 2013, 13(2), 2579-2594; https://doi.org/10.3390/s130202579
Received: 4 January 2013 / Revised: 4 February 2013 / Accepted: 8 February 2013 / Published: 20 February 2013
Cited by 13 | Viewed by 3003 | PDF Full-text (1559 KB) | HTML Full-text | XML Full-text
Abstract
Terrestrial laser scanning is of increasing importance for surveying and hazard assessments. Digital terrain models are generated using the resultant data to analyze surface processes. In order to determine the terrain surface as precisely as possible, it is often necessary to filter out [...] Read more.
Terrestrial laser scanning is of increasing importance for surveying and hazard assessments. Digital terrain models are generated using the resultant data to analyze surface processes. In order to determine the terrain surface as precisely as possible, it is often necessary to filter out points that do not represent the terrain surface. Examples are vegetation, vehicles, and animals. Filtering in mountainous terrain is more difficult than in other topography types. Here, existing automatic filtering solutions are not acceptable, because they are usually designed for airborne scan data. The present article describes a method specifically suitable for filtering terrestrial laser scanning data. This method is based on the direct line of sight between the scanner and the measured point and the assumption that no other surface point can be located in the area above this connection line. This assumption is only true for terrestrial laser data, but not for airborne data. We present a comparison of the wedge filtering to a modified inverse distance filtering method (IDWMO) filtered point cloud data. Both methods use manually filtered surfaces as reference. The comparison shows that the mean error and root–mean-square-error (RSME) between the results and the manually filtered surface of the two methods are similar. A significantly higher number of points of the terrain surface could be preserved, however, using the wedge-filtering approach. Therefore, we suggest that wedge-filtering should be integrated as a further parameter into already existing filtering processes, but is not suited as a standalone solution so far. Full article
(This article belongs to the Special Issue Laser Sensing and Imaging)
Open AccessArticle Photonic Crystal Biosensor Based on Optical Surface Waves
Sensors 2013, 13(2), 2566-2578; https://doi.org/10.3390/s130202566
Received: 11 January 2013 / Revised: 7 February 2013 / Accepted: 8 February 2013 / Published: 19 February 2013
Cited by 43 | Viewed by 4484 | PDF Full-text (2703 KB) | HTML Full-text | XML Full-text
Abstract
A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle [...] Read more.
A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately. Full article
(This article belongs to the Special Issue Photonic Crystal Sensors)
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Open AccessArticle A Novel Two-Axis Load Sensor Designed for in Situ Scratch Testing inside Scanning Electron Microscopes
Sensors 2013, 13(2), 2552-2565; https://doi.org/10.3390/s130202552
Received: 16 December 2012 / Revised: 29 January 2013 / Accepted: 29 January 2013 / Published: 18 February 2013
Cited by 2 | Viewed by 2783 | PDF Full-text (799 KB) | HTML Full-text | XML Full-text
Abstract
Because of a lack of available miniaturized multiaxial load sensors to measure the normal load and the lateral load simultaneously, quantitative in situ scratch devices inside scanning electron microscopes and the transmission electron microscopes have barely been developed up to now. A novel [...] Read more.
Because of a lack of available miniaturized multiaxial load sensors to measure the normal load and the lateral load simultaneously, quantitative in situ scratch devices inside scanning electron microscopes and the transmission electron microscopes have barely been developed up to now. A novel two-axis load sensor was designed in this paper. With an I-shaped structure, the sensor has the function of measuring the lateral load and the normal load simultaneously, and at the same time it has compact dimensions. Finite element simulations were carried out to evaluate stiffness and modal characteristics. A decoupling algorithm was proposed to resolve the cross-coupling between the two-axis loads. Natural frequency of the sensor was tested. Linearity and decoupling parameters were obtained from the calibration experiments, which indicate that the sensor has good linearity and the cross-coupling between the two axes is not strong. Via the decoupling algorithm and the corresponding decoupling parameters, simultaneous measurement of the lateral load and the normal load can be realized via the developed two-axis load sensor. Preliminary applications of the load sensor for scratch testing indicate that the load sensor can work well during the scratch testing. Taking advantage of the compact structure, it has the potential ability for applications in quantitative in situ scratch testing inside SEMs. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Heart Sound Biometric System Based on Marginal Spectrum Analysis
Sensors 2013, 13(2), 2530-2551; https://doi.org/10.3390/s130202530
Received: 14 November 2012 / Revised: 28 January 2013 / Accepted: 4 February 2013 / Published: 18 February 2013
Cited by 14 | Viewed by 3709 | PDF Full-text (673 KB) | HTML Full-text | XML Full-text
Abstract
This work presents a heart sound biometric system based on marginal spectrum analysis, which is a new feature extraction technique for identification purposes. This heart sound identification system is comprised of signal acquisition, pre-processing, feature extraction, training, and identification. Experiments on the selection [...] Read more.
This work presents a heart sound biometric system based on marginal spectrum analysis, which is a new feature extraction technique for identification purposes. This heart sound identification system is comprised of signal acquisition, pre-processing, feature extraction, training, and identification. Experiments on the selection of the optimal values for the system parameters are conducted. The results indicate that the new spectrum coefficients result in a significant increase in the recognition rate of 94.40% compared with that of the traditional Fourier spectrum (84.32%) based on a database of 280 heart sounds from 40 participants. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Forgery Detection and Value Identification of Euro Banknotes
Sensors 2013, 13(2), 2515-2529; https://doi.org/10.3390/s130202515
Received: 18 December 2012 / Revised: 29 January 2013 / Accepted: 4 February 2013 / Published: 18 February 2013
Cited by 16 | Viewed by 3885 | PDF Full-text (1532 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes both hardware and software components to detect counterfeits of Euro banknotes. The proposed system is also able to recognize the banknote values. Differently than other state-of-the-art methods, the proposed approach makes use of banknote images acquired with a near infrared [...] Read more.
This paper describes both hardware and software components to detect counterfeits of Euro banknotes. The proposed system is also able to recognize the banknote values. Differently than other state-of-the-art methods, the proposed approach makes use of banknote images acquired with a near infrared camera to perform recognition and authentication. This allows one to build a system that can effectively deal with real forgeries, which are usually not detectable with visible light. The hardware does not use any mechanical parts, so the overall system is low-cost. The proposed solution is reliable for ambient light and banknote positioning. Users should simply lean the banknote to be analyzed on a flat glass, and the system detects forgery, as well as recognizes the banknote value. The effectiveness of the proposed solution has been properly tested on a dataset composed by genuine and fake Euro banknotes provided by Italy's central bank. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle High Throughput Molecular Confirmation of β-Thalassemia Mutations Using Novel TaqMan Probes
Sensors 2013, 13(2), 2506-2514; https://doi.org/10.3390/s130202506
Received: 22 November 2012 / Revised: 25 January 2013 / Accepted: 6 February 2013 / Published: 18 February 2013
Cited by 6 | Viewed by 2977 | PDF Full-text (906 KB) | HTML Full-text | XML Full-text
Abstract
β-Thalassemia is a public health problem where 4.5% of Malaysians are β-thalassemia carriers. The genetic disorder is caused by defects in the β-globin gene complex which lead to reduced or complete absence of β-globin chain synthesis. Five TaqMan genotyping assays were designed and [...] Read more.
β-Thalassemia is a public health problem where 4.5% of Malaysians are β-thalassemia carriers. The genetic disorder is caused by defects in the β-globin gene complex which lead to reduced or complete absence of β-globin chain synthesis. Five TaqMan genotyping assays were designed and developed to detect the common β-thalassemia mutations in Malaysian Malays. The assays were evaluated with 219 "blinded" DNA samples and the results showed 100% sensitivity and specificity. The in-house designed TaqMan genotyping assays were found to be cost- and time-effective for characterization of β-thalassemia mutations in the Malaysian population. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Hardware Implementation of Lorenz Circuit Systems for Secure Chaotic Communication Applications
Sensors 2013, 13(2), 2494-2505; https://doi.org/10.3390/s130202494
Received: 4 January 2013 / Revised: 7 February 2013 / Accepted: 8 February 2013 / Published: 18 February 2013
Cited by 9 | Viewed by 2903 | PDF Full-text (508 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the synchronization between the master and slave Lorenz chaotic systems by slide mode controller (SMC)-based technique. A proportional-integral (PI) switching surface is proposed to simplify the task of assigning the performance of the closed-loop error system in sliding mode. Then, [...] Read more.
This paper presents the synchronization between the master and slave Lorenz chaotic systems by slide mode controller (SMC)-based technique. A proportional-integral (PI) switching surface is proposed to simplify the task of assigning the performance of the closed-loop error system in sliding mode. Then, extending the concept of equivalent control and using some basic electronic components, a secure communication system is constructed. Experimental results show the feasibility of synchronizing two Lorenz circuits via the proposed SMC. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Detection of Micrococcus Luteus Biofilm Formation in Microfluidic Environments by pH Measurement Using an Ion-Sensitive Field-Effect Transistor
Sensors 2013, 13(2), 2484-2493; https://doi.org/10.3390/s130202484
Received: 26 December 2012 / Revised: 8 February 2013 / Accepted: 10 February 2013 / Published: 18 February 2013
Cited by 12 | Viewed by 3891 | PDF Full-text (653 KB) | HTML Full-text | XML Full-text
Abstract
Biofilm formation in microfluidic channels is difficult to detect because sampling volumes are too small for conventional turbidity measurements. To detect biofilm formation, we used an ion-sensitive field-effect transistor (ISFET) measurement system to measure pH changes in small volumes of bacterial suspension. Cells [...] Read more.
Biofilm formation in microfluidic channels is difficult to detect because sampling volumes are too small for conventional turbidity measurements. To detect biofilm formation, we used an ion-sensitive field-effect transistor (ISFET) measurement system to measure pH changes in small volumes of bacterial suspension. Cells of Micrococcus luteus (M. luteus) were cultured in polystyrene (PS) microtubes and polymethylmethacrylate (PMMA)-based microfluidic channels laminated with polyvinylidene chloride. In microtubes, concentrations of bacteria and pH in the suspension were analyzed by measuring turbidity and using an ISFET sensor, respectively. In microfluidic channels containing 20 μL of bacterial suspension, we measured pH changes using the ISFET sensor and monitored biofilm formation using a microscope. We detected acidification and alkalinization phases of M. luteus from the ISFET sensor signals in both microtubes and microfluidic channels. In the alkalinization phase, after 2 day culture, dense biofilm formation was observed at the bottom of the microfluidic channels. In this study, we used an ISFET sensor to detect biofilm formation in clinical and industrial microfluidic environments by detecting alkalinization of the culture medium. Full article
(This article belongs to the Special Issue Microfluidic Devices)
Open AccessArticle Performance Enhancement of a GaAs Detector with a Vertical Field and an Embedded Thin Low-Temperature Grown Layer
Sensors 2013, 13(2), 2475-2483; https://doi.org/10.3390/s130202475
Received: 17 December 2012 / Revised: 6 February 2013 / Accepted: 8 February 2013 / Published: 18 February 2013
Cited by 4 | Viewed by 3016 | PDF Full-text (432 KB) | HTML Full-text | XML Full-text
Abstract
Low temperature growth of GaAs (LT-GaAs) near 200 °C results in a recombination lifetime of nearly 1 ps, compared with approximately 1 ns for regular temperature ~600 °C grown GaAs (RT-GaAs), making it suitable for ultra high speed detection applications. However, LT-GaAs detectors [...] Read more.
Low temperature growth of GaAs (LT-GaAs) near 200 °C results in a recombination lifetime of nearly 1 ps, compared with approximately 1 ns for regular temperature ~600 °C grown GaAs (RT-GaAs), making it suitable for ultra high speed detection applications. However, LT-GaAs detectors usually suffer from low responsivity due to low carrier mobility. Here we report electro-optic sampling time response measurements of a detector that employs an AlGaAs heterojunction, a thin layer of LT-GaAs, a channel of RT-GaAs, and a vertical electric field that together facilitate collection of optically generated electrons while suppressing collection of lower mobility holes. Consequently, these devices have detection efficiency near that of RT-GaAs yet provide pulse widths nearly an order of magnitude faster—~6 ps for a cathode-anode separation of 1.3 μm and ~12 ps for distances more than 3 μm. Full article
(This article belongs to the Special Issue Photodetectors)
Open AccessReview Progress in the Development of CdZnTe Unipolar Detectors for Different Anode Geometries and Data Corrections
Sensors 2013, 13(2), 2447-2474; https://doi.org/10.3390/s130202447
Received: 14 November 2012 / Revised: 25 January 2013 / Accepted: 5 February 2013 / Published: 18 February 2013
Cited by 26 | Viewed by 3555 | PDF Full-text (2281 KB) | HTML Full-text | XML Full-text
Abstract
CdZnTe detectors have been under development for the past two decades, providing good stopping power for gamma rays, lightweight camera heads and improved energy resolution. However, the performance of this type of detector is limited primarily by incomplete charge collection problems resulting from [...] Read more.
CdZnTe detectors have been under development for the past two decades, providing good stopping power for gamma rays, lightweight camera heads and improved energy resolution. However, the performance of this type of detector is limited primarily by incomplete charge collection problems resulting from charge carriers trapping. This paper is a review of the progress in the development of CdZnTe unipolar detectors with some data correction techniques for improving performance of the detectors. We will first briefly review the relevant theories. Thereafter, two aspects of the techniques for overcoming the hole trapping issue are summarized, including irradiation direction configuration and pulse shape correction methods. CdZnTe detectors of different geometries are discussed in detail, covering the principal of the electrode geometry design, the design and performance characteristics, some detector prototypes development and special correction techniques to improve the energy resolution. Finally, the state of art development of 3-D position sensing and Compton imaging technique are also discussed. Spectroscopic performance of CdZnTe semiconductor detector will be greatly improved even to approach the statistical limit on energy resolution with the combination of some of these techniques. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Fusion of Building Information and Range Imaging for Autonomous Location Estimation in Indoor Environments
Sensors 2013, 13(2), 2430-2446; https://doi.org/10.3390/s130202430
Received: 15 October 2012 / Revised: 4 February 2013 / Accepted: 4 February 2013 / Published: 14 February 2013
Cited by 4 | Viewed by 3676 | PDF Full-text (1241 KB) | HTML Full-text | XML Full-text
Abstract
We present a novel approach for autonomous location estimation and navigation in indoor environments using range images and prior scene knowledge from a GIS database (CityGML). What makes this task challenging is the arbitrary relative spatial relation between GIS and Time-of-Flight (ToF) range [...] Read more.
We present a novel approach for autonomous location estimation and navigation in indoor environments using range images and prior scene knowledge from a GIS database (CityGML). What makes this task challenging is the arbitrary relative spatial relation between GIS and Time-of-Flight (ToF) range camera further complicated by a markerless configuration. We propose to estimate the camera’s pose solely based on matching of GIS objects and their detected location in image sequences. We develop a coarse-to-fine matching strategy that is able to match point clouds without any initial parameters. Experiments with a state-of-the-art ToF point cloud show that our proposed method delivers an absolute camera position with decimeter accuracy, which is sufficient for many real-world applications (e.g., collision avoidance). Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Light-Intensity-Induced Characterization of Elastic Constants and d33 Piezoelectric Coefficient of PLZT Single Fiber Based Transducers
Sensors 2013, 13(2), 2419-2429; https://doi.org/10.3390/s130202419
Received: 20 December 2012 / Revised: 28 January 2013 / Accepted: 2 February 2013 / Published: 12 February 2013
Cited by 4 | Viewed by 3460 | PDF Full-text (840 KB) | HTML Full-text | XML Full-text
Abstract
Enhanced functionality of electro-optic devices by implementing piezoelectric micro fibers into their construction is proposed. Lanthanum-modified lead zirconate titanate (PLZT) ceramics are known to exhibit high light transparency, desirable electro-optic properties and fast response. In this study PLZT fibers with a diameter of [...] Read more.
Enhanced functionality of electro-optic devices by implementing piezoelectric micro fibers into their construction is proposed. Lanthanum-modified lead zirconate titanate (PLZT) ceramics are known to exhibit high light transparency, desirable electro-optic properties and fast response. In this study PLZT fibers with a diameter of around 300 microns were produced by a thermoplastic processing method and their light-induced impedance and piezoelectric coefficient were investigated at relatively low light intensity (below 50 mW/cm2). The authors experimentally proved higher performance of light controlled microfiber transducers in comparison to their bulk form. The advantage of the high surface area to volume ratio is shown to be an excellent technique to design high quality light sensors by using fibrous materials. The UV absorption induced change in elastic constants of 3% and 4% for the piezoelectric coefficient d33. Full article
(This article belongs to the Special Issue Piezoelectric Sensors and Actuators)
Open AccessArticle An Infrastructureless Approach to Estimate Vehicular Density in Urban Environments
Sensors 2013, 13(2), 2399-2418; https://doi.org/10.3390/s130202399
Received: 8 January 2013 / Revised: 25 January 2013 / Accepted: 30 January 2013 / Published: 11 February 2013
Cited by 24 | Viewed by 3371 | PDF Full-text (1238 KB) | HTML Full-text | XML Full-text
Abstract
In Vehicular Networks, communication success usually depends on the density of vehicles, since a higher density allows having shorter and more reliable wireless links. Thus, knowing the density of vehicles in a vehicular communications environment is important, as better opportunities for wireless communication [...] Read more.
In Vehicular Networks, communication success usually depends on the density of vehicles, since a higher density allows having shorter and more reliable wireless links. Thus, knowing the density of vehicles in a vehicular communications environment is important, as better opportunities for wireless communication can show up. However, vehicle density is highly variable in time and space. This paper deals with the importance of predicting the density of vehicles in vehicular environments to take decisions for enhancing the dissemination of warning messages between vehicles. We propose a novel mechanism to estimate the vehicular density in urban environments. Our mechanism uses as input parameters the number of beacons received per vehicle, and the topological characteristics of the environment where the vehicles are located. Simulation results indicate that, unlike previous proposals solely based on the number of beacons received, our approach is able to accurately estimate the vehicular density, and therefore it could support more efficient dissemination protocols for vehicular environments, as well as improve previously proposed schemes. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Rapid Characterization of Vegetation Structure with a Microsoft Kinect Sensor
Sensors 2013, 13(2), 2384-2398; https://doi.org/10.3390/s130202384
Received: 14 November 2012 / Revised: 26 December 2012 / Accepted: 31 January 2013 / Published: 11 February 2013
Cited by 63 | Viewed by 4638 | PDF Full-text (6753 KB) | HTML Full-text | XML Full-text
Abstract
The importance of vegetation structure and biomass in controlling land-atmosphere exchange is widely recognized, but measurements of canopy structure are challenging, time consuming, and often rely on destructive methods. The Microsoft Kinect is an infrared sensor designed for video gaming that outputs synchronized [...] Read more.
The importance of vegetation structure and biomass in controlling land-atmosphere exchange is widely recognized, but measurements of canopy structure are challenging, time consuming, and often rely on destructive methods. The Microsoft Kinect is an infrared sensor designed for video gaming that outputs synchronized color and depth images and that has the potential to allow rapid characterization of vegetation structure. We compared depth images from a Kinect sensor with manual measurements of plant structure and size for two species growing in a California grassland. The depth images agreed well with the horizontal and vertical measurements of plant size made manually. Similarly, the plant volumes calculated with a three-dimensional convex hulls approach was well related to plant biomass. The Kinect showed some limitations for ecological observation associated with a short measurement range and daytime light contamination. Nonetheless, the Kinect’s light weight, fast acquisition time, low power requirement, and cost make it a promising tool for rapid field surveys of canopy structure, especially in small-statured vegetation. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Development of a Compact Wireless Laplacian Electrode Module for Electromyograms and Its Human Interface Applications
Sensors 2013, 13(2), 2368-2383; https://doi.org/10.3390/s130202368
Received: 7 December 2012 / Revised: 24 January 2013 / Accepted: 2 February 2013 / Published: 8 February 2013
Cited by 6 | Viewed by 3770 | PDF Full-text (875 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we developed a compact wireless Laplacian electrode module for electromyograms (EMGs). One of the advantages of the Laplacian electrode configuration is that EMGs obtained with it are expected to be sensitive to the firing of the muscle directly beneath the [...] Read more.
In this study, we developed a compact wireless Laplacian electrode module for electromyograms (EMGs). One of the advantages of the Laplacian electrode configuration is that EMGs obtained with it are expected to be sensitive to the firing of the muscle directly beneath the measurement site. The performance of the developed electrode module was investigated in two human interface applications: character-input interface and detection of finger movement during finger Braille typing. In the former application, the electrode module was combined with an EMG-mouse click converter circuit. In the latter, four electrode modules were used for detection of finger movements during finger Braille typing. Investigation on the character-input interface indicated that characters could be input stably by contraction of (a) the masseter, (b) trapezius, (c) anterior tibialis and (d) flexor carpi ulnaris muscles. This wide applicability is desirable when the interface is applied to persons with physical disabilities because the disability differs one to another. The investigation also demonstrated that the electrode module can work properly without any skin preparation. Finger movement detection experiments showed that each finger movement was more clearly detectable when comparing to EMGs recorded with conventional electrodes, suggesting that the Laplacian electrode module is more suitable for detecting the timing of finger movement during typing. This could be because the Laplacian configuration enables us to record EMGs just beneath the electrode. These results demonstrate the advantages of the Laplacian electrode module. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2012)
Open AccessArticle Energy Harvesting Thermoelectric Generators Manufactured Using the Complementary Metal Oxide Semiconductor Process
Sensors 2013, 13(2), 2359-2367; https://doi.org/10.3390/s130202359
Received: 31 December 2012 / Revised: 6 February 2013 / Accepted: 7 February 2013 / Published: 8 February 2013
Cited by 18 | Viewed by 3976 | PDF Full-text (527 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the fabrication and characterization of energy harvesting thermoelectric micro generators using the commercial complementary metal oxide semiconductor (CMOS) process. The micro generator consists of 33 thermocouples in series. Thermocouple materials are p-type and n-type polysilicon since they have a large [...] Read more.
This paper presents the fabrication and characterization of energy harvesting thermoelectric micro generators using the commercial complementary metal oxide semiconductor (CMOS) process. The micro generator consists of 33 thermocouples in series. Thermocouple materials are p-type and n-type polysilicon since they have a large Seebeck coefficient difference. The output power of the micro generator depends on the temperature difference in the hot and cold parts of the thermocouples. In order to increase this temperature difference, the hot part of the thermocouples is suspended to reduce heat-sinking. The micro generator needs a post-CMOS process to release the suspended structures of hot part, which the post-process includes an anisotropic dry etching to etch the sacrificial oxide layer and an isotropic dry etching to remove the silicon substrate. Experiments show that the output power of the micro generator is 9.4 mW at a temperature difference of 15 K. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2013)
Open AccessArticle High-Visibility Photonic Crystal Fiber Interferometer as Multifunctional Sensor
Sensors 2013, 13(2), 2349-2358; https://doi.org/10.3390/s130202349
Received: 31 December 2012 / Accepted: 4 February 2013 / Published: 8 February 2013
Cited by 22 | Viewed by 3265 | PDF Full-text (762 KB) | HTML Full-text | XML Full-text
Abstract
A photonic crystal fiber (PCF) interferometer that exhibits record fringe contrast (~40 dB) is demonstrated along with its sensing applications. The device operates in reflection mode and consists of a centimeter-long segment of properly selected PCF fusion spliced to single mode optical fibers. [...] Read more.
A photonic crystal fiber (PCF) interferometer that exhibits record fringe contrast (~40 dB) is demonstrated along with its sensing applications. The device operates in reflection mode and consists of a centimeter-long segment of properly selected PCF fusion spliced to single mode optical fibers. Two identical collapsed zones in the PCF combined with its modal properties allow high-visibility interference patterns. The interferometer is suitable for refractometric and liquid level sensing. The measuring refractive index range goes from 1.33 to 1.43 and the maximum resolution is ~1.6 × 10−5. Full article
(This article belongs to the Special Issue Photonic Crystal Sensors)
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Open AccessReview Diverse Applications of Electronic-Nose Technologies in Agriculture and Forestry
Sensors 2013, 13(2), 2295-2348; https://doi.org/10.3390/s130202295
Received: 1 December 2012 / Revised: 30 January 2013 / Accepted: 30 January 2013 / Published: 8 February 2013
Cited by 110 | Viewed by 5915 | PDF Full-text (561 KB) | HTML Full-text | XML Full-text
Abstract
Electronic-nose (e-nose) instruments, derived from numerous types of aroma-sensor technologies, have been developed for a diversity of applications in the broad fields of agriculture and forestry. Recent advances in e-nose technologies within the plant sciences, including improvements in gas-sensor designs, innovations in data [...] Read more.
Electronic-nose (e-nose) instruments, derived from numerous types of aroma-sensor technologies, have been developed for a diversity of applications in the broad fields of agriculture and forestry. Recent advances in e-nose technologies within the plant sciences, including improvements in gas-sensor designs, innovations in data analysis and pattern-recognition algorithms, and progress in material science and systems integration methods, have led to significant benefits to both industries. Electronic noses have been used in a variety of commercial agricultural-related industries, including the agricultural sectors of agronomy, biochemical processing, botany, cell culture, plant cultivar selections, environmental monitoring, horticulture, pesticide detection, plant physiology and pathology. Applications in forestry include uses in chemotaxonomy, log tracking, wood and paper processing, forest management, forest health protection, and waste management. These aroma-detection applications have improved plant-based product attributes, quality, uniformity, and consistency in ways that have increased the efficiency and effectiveness of production and manufacturing processes. This paper provides a comprehensive review and summary of a broad range of electronic-nose technologies and applications, developed specifically for the agriculture and forestry industries over the past thirty years, which have offered solutions that have greatly improved worldwide agricultural and agroforestry production systems. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle Statistical Modeling of Large-Scale Signal Path Loss in Underwater Acoustic Networks
Sensors 2013, 13(2), 2279-2294; https://doi.org/10.3390/s130202279
Received: 28 December 2012 / Revised: 6 February 2013 / Accepted: 7 February 2013 / Published: 8 February 2013
Cited by 12 | Viewed by 3596 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power [...] Read more.
In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation), we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc.), an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc.). Full article
(This article belongs to the Special Issue Last Trends in Acoustic Sensing)
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Open AccessArticle Label-Free Potentiometry for Detecting DNA Hybridization Using Peptide Nucleic Acid and DNA Probes
Sensors 2013, 13(2), 2267-2278; https://doi.org/10.3390/s130202267
Received: 25 October 2012 / Revised: 15 January 2013 / Accepted: 4 February 2013 / Published: 7 February 2013
Cited by 24 | Viewed by 4742 | PDF Full-text (479 KB) | HTML Full-text | XML Full-text
Abstract
Peptide nucleic acid (PNA) has outstanding affinity over DNA for complementary nucleic acid sequences by forming a PNA-DNA heterodimer upon hybridization via Watson-Crick base-pairing. To verify whether PNA probes on an electrode surface enhance sensitivity for potentiometric DNA detection or not, we conducted [...] Read more.
Peptide nucleic acid (PNA) has outstanding affinity over DNA for complementary nucleic acid sequences by forming a PNA-DNA heterodimer upon hybridization via Watson-Crick base-pairing. To verify whether PNA probes on an electrode surface enhance sensitivity for potentiometric DNA detection or not, we conducted a comparative study on the hybridization of PNA and DNA probes on the surface of a 10-channel gold electrodes microarray. Changes in the charge density as a result of hybridization at the solution/electrode interface on the self-assembled monolayer (SAM)-formed microelectrodes were directly transformed into potentiometric signals using a high input impedance electrometer. The charge readout allows label-free, reagent-less, and multi-parallel detection of target oligonucleotides without any optical assistance. The differences in the probe lengths between 15- to 22-mer dramatically influenced on the sensitivity of the PNA and DNA sensors. Molecular type of the capturing probe did not affect the degree of potential shift. Theoretical model for charged rod-like duplex using the Gouy-Chapman equation indicates the dominant effect of electrostatic attractive forces between anionic DNA and underlying electrode at the electrolyte/electrode interface in the potentiometry. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2012)
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Open AccessArticle Investigations on a Novel Inductive Concept Frequency Technique for the Grading of Oil Palm Fresh Fruit Bunches
Sensors 2013, 13(2), 2254-2266; https://doi.org/10.3390/s130202254
Received: 18 December 2012 / Revised: 30 January 2013 / Accepted: 4 February 2013 / Published: 7 February 2013
Cited by 11 | Viewed by 4066 | PDF Full-text (783 KB) | HTML Full-text | XML Full-text
Abstract
From the Malaysian harvester’s perspective, the determination of the ripeness of the oil palm (FFB) is a critical factor to maximize palm oil production. A preliminary study of a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunches [...] Read more.
From the Malaysian harvester’s perspective, the determination of the ripeness of the oil palm (FFB) is a critical factor to maximize palm oil production. A preliminary study of a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunches is presented. To optimize the functionality of the sensor, the frequency characteristics of air coils of various diameters are investigated to determine their inductance and resonant characteristics. Sixteen samples from two categories, namely ripe oil palm fruitlets and unripe oil palm fruitlets, are tested from 100 Hz up to 100 MHz frequency. The results showed the inductance and resonant characteristics of the air coil sensors display significant changes among the samples of each category. The investigations on the frequency characteristics of the sensor air coils are studied to observe the effect of variations in the coil diameter. The effect of coil diameter yields a significant 0.02643 MHz difference between unripe samples to air and 0.01084 MHz for ripe samples to air. The designed sensor exhibits significant potential in determining the maturity of oil palm fruits. Full article
(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)
Open AccessArticle Architecture for Multi-Technology Real-Time Location Systems
Sensors 2013, 13(2), 2220-2253; https://doi.org/10.3390/s130202220
Received: 28 December 2012 / Revised: 22 January 2013 / Accepted: 5 February 2013 / Published: 7 February 2013
Cited by 8 | Viewed by 3281 | PDF Full-text (1306 KB) | HTML Full-text | XML Full-text
Abstract
The rising popularity of location-based services has prompted considerable research in the field of indoor location systems. Since there is no single technology to support these systems, it is necessary to consider the fusion of the information coming from heterogeneous sensors. This paper [...] Read more.
The rising popularity of location-based services has prompted considerable research in the field of indoor location systems. Since there is no single technology to support these systems, it is necessary to consider the fusion of the information coming from heterogeneous sensors. This paper presents a software architecture designed for a hybrid location system where we can merge information from multiple sensor technologies. The architecture was designed to be used by different kinds of actors independently and with mutual transparency: hardware administrators, algorithm developers and user applications. The paper presents the architecture design, work-flow, case study examples and some results to show how different technologies can be exploited to obtain a good estimation of a target position. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle Frequency Noise Properties of Lasers for Interferometry in Nanometrology
Sensors 2013, 13(2), 2206-2219; https://doi.org/10.3390/s130202206
Received: 26 November 2012 / Revised: 31 January 2013 / Accepted: 4 February 2013 / Published: 7 February 2013
Cited by 22 | Viewed by 3015 | PDF Full-text (886 KB) | HTML Full-text | XML Full-text
Abstract
In this contribution we focus on laser frequency noise properties and their influence on the interferometric displacement measurements. A setup for measurement of laser frequency noise is proposed and tested together with simultaneous measurement of fluctuations in displacement in the Michelson interferometer. Several [...] Read more.
In this contribution we focus on laser frequency noise properties and their influence on the interferometric displacement measurements. A setup for measurement of laser frequency noise is proposed and tested together with simultaneous measurement of fluctuations in displacement in the Michelson interferometer. Several laser sources, including traditional He-Ne and solid-state lasers, and their noise properties are evaluated and compared. The contribution of the laser frequency noise to the displacement measurement is discussed in the context of other sources of uncertainty associated with the interferometric setup, such as, mechanics, resolution of analog-to-digital conversion, frequency bandwidth of the detection chain, and variations of the refractive index of air. Full article
(This article belongs to the Special Issue Laser Sensing and Imaging)
Open AccessArticle Monolithically Integrated Mid-Infrared Quantum Cascade Laser and Detector
Sensors 2013, 13(2), 2196-2205; https://doi.org/10.3390/s130202196
Received: 4 January 2013 / Revised: 30 January 2013 / Accepted: 1 February 2013 / Published: 6 February 2013
Cited by 18 | Viewed by 3823 | PDF Full-text (356 KB) | HTML Full-text | XML Full-text
Abstract
We demonstrate the monolithic integration of a mid-infrared laser and detector utilizing a bi-functional quantum cascade active region. When biased, this active region provides optical gain, while it can be used as a detector at zero bias. With our novel approach we can [...] Read more.
We demonstrate the monolithic integration of a mid-infrared laser and detector utilizing a bi-functional quantum cascade active region. When biased, this active region provides optical gain, while it can be used as a detector at zero bias. With our novel approach we can measure the light intensity of the laser on the same chip without the need of external lenses or detectors. Based on a bound-to-continuum design, the bi-functional active region has an inherent broad electro-luminescence spectrum of 200 cm-1, which indicates its use for single mode laser arrays. We have measured a peak signal of 191.5 mV at the on-chip detector, without any amplification. The room-temperature pulsed emission with an averaged power consumption of 4 mW and the high-speed detection makes these devices ideal for low-power sensors. The combination of the on-chip detection functionality, the broad emission spectrum and the low average power consumption indicates the potential of our bi-functional quantum cascade structures to build a mid-infrared lab-on-a-chip based on quantum cascade laser technology. Full article
(This article belongs to the Special Issue Laser Sensing and Imaging)
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