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Sensors, Volume 9, Issue 5 (May 2009), Pages 3161-4021

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Open AccessArticle Artificial Roughness Encoding with a Bio-inspired MEMS-based Tactile Sensor Array
Sensors 2009, 9(5), 3161-3183; doi:10.3390/s90503161
Received: 3 March 2009 / Revised: 22 April 2009 / Accepted: 24 April 2009 / Published: 27 April 2009
Cited by 32 | PDF Full-text (1484 KB) | HTML Full-text | XML Full-text
Abstract
A compliant 2x2 tactile sensor array was developed and investigated for roughness encoding. State of the art cross shape 3D MEMS sensors were integrated with polymeric packaging providing in total 16 sensitive elements to external mechanical stimuli in an area of about [...] Read more.
A compliant 2x2 tactile sensor array was developed and investigated for roughness encoding. State of the art cross shape 3D MEMS sensors were integrated with polymeric packaging providing in total 16 sensitive elements to external mechanical stimuli in an area of about 20 mm2, similarly to the SA1 innervation density in humans. Experimental analysis of the bio-inspired tactile sensor array was performed by using ridged surfaces, with spatial periods from 2.6 mm to 4.1 mm, which were indented with regulated 1N normal force and stroked at constant sliding velocity from 15 mm/s to 48 mm/s. A repeatable and expected frequency shift of the sensor outputs depending on the applied stimulus and on its scanning velocity was observed between 3.66 Hz and 18.46 Hz with an overall maximum error of 1.7%. The tactile sensor could also perform contact imaging during static stimulus indentation. The experiments demonstrated the suitability of this approach for the design of a roughness encoding tactile sensor for an artificial fingerpad. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
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Open AccessArticle Use of Human Senses as Sensors
Sensors 2009, 9(5), 3184-3204; doi:10.3390/s90503184
Received: 22 January 2009 / Revised: 14 April 2009 / Accepted: 27 April 2009 / Published: 27 April 2009
Cited by 5 | PDF Full-text (688 KB) | HTML Full-text | XML Full-text
Abstract
This paper is an overview of our recent findings obtained by the use of human senses as sensors, suggesting that human senses might be indispensable sensors, not only for practical uses but also for gaining a deeper understanding of humans. From this [...] Read more.
This paper is an overview of our recent findings obtained by the use of human senses as sensors, suggesting that human senses might be indispensable sensors, not only for practical uses but also for gaining a deeper understanding of humans. From this point of view, two kinds of studies, both based on semantic responses of participants, deserve emphasis. One study assessed the efficacy of the photocatalytic elimination of stains or bio-aerosols from an air environment using TiO2 as well as the photocatalytic deodorizing efficacy of a TiO2-type deodorizer; the other study evaluated the changes in perception of a given aroma while inhaling the fragrance of essential oils. In the latter study, we employed a sensory test for evaluating changes in perception of a given aroma. Sensory tests were conducted twice, when participants were undergoing the Kraepelin mental performance test (mental arithmetic) or an auditory task (listening to environmental natural sounds), once before the task (pre-task) and once after the task (post-task). The perception of fragrance was assessed by 13 contrasting pairs of adjectives as a function of the task assigned to participants. The obtained findings illustrate subtle nuances regarding how essential oils manifest their potency and how olfactory discrimination and responses occur in humans. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
Open AccessArticle Development of 3D Force Sensors for Nanopositioning and Nanomeasuring Machine
Sensors 2009, 9(5), 3228-3239; doi:10.3390/s90503228
Received: 3 April 2009 / Revised: 20 April 2009 / Accepted: 24 April 2009 / Published: 28 April 2009
Cited by 16 | PDF Full-text (359 KB) | HTML Full-text | XML Full-text
Abstract
In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure [...] Read more.
In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure for the force sensors. All designs have 16 p-type diffused piezoresistors on the surface of the membrane. Sensitivities in x, y and z directions are measured. Simulated and measured stiffness ratio in horizontal to vertical direction is measured for each design. Effect of the length of the stylus on H:V stiffness ratio is studied. Minimum and maximum deflection and resonance frequency are measured for all designs. The sensors were placed in a nanopositioning and nanomeasuring machine and one point measurements were performed for all the designs. Lastly the application of the sensor is shown, where dimension of a cube is measured using the sensor. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle Development of a Sensor Node for Precision Horticulture
Sensors 2009, 9(5), 3240-3255; doi:10.3390/s90503240
Received: 9 March 2009 / Revised: 31 March 2009 / Accepted: 27 April 2009 / Published: 28 April 2009
Cited by 16 | PDF Full-text (1418 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the design of a new wireless sensor node (GAIA Soil-Mote) for precision horticulture applications which permits the use of precision agricultural instruments based on the SDI-12 standard. Wireless communication is achieved with a transceiver compliant with the IEEE 802.15.4 [...] Read more.
This paper presents the design of a new wireless sensor node (GAIA Soil-Mote) for precision horticulture applications which permits the use of precision agricultural instruments based on the SDI-12 standard. Wireless communication is achieved with a transceiver compliant with the IEEE 802.15.4 standard. The GAIA Soil-Mote software implementation is based on TinyOS. A two-phase methodology was devised to validate the design of this sensor node. The first phase consisted of laboratory validation of the proposed hardware and software solution, including a study on power consumption and autonomy. The second phase consisted of implementing a monitoring application in a real broccoli (Brassica oleracea L. var Marathon) crop in Campo de Cartagena in south-east Spain. In this way the sensor node was validated in real operating conditions. This type of application was chosen because there is a large potential market for it in the farming sector, especially for the development of precision agriculture applications. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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Open AccessArticle Comparison of Low Cost Miniature Spectrometers for Volcanic SO2 Emission Measurements
Sensors 2009, 9(5), 3256-3268; doi:10.3390/s90503256
Received: 17 March 2009 / Revised: 28 April 2009 / Accepted: 28 April 2009 / Published: 28 April 2009
Cited by 8 | PDF Full-text (82 KB) | HTML Full-text | XML Full-text
Abstract
Miniature ultraviolet USB coupled spectrometers have become ubiquitously applied over the last decade for making volcanic SO2 emission rate measurements. The dominantly applied unit has recently been discontinued however, raising the question of which currently available devices should now be implemented. [...] Read more.
Miniature ultraviolet USB coupled spectrometers have become ubiquitously applied over the last decade for making volcanic SO2 emission rate measurements. The dominantly applied unit has recently been discontinued however, raising the question of which currently available devices should now be implemented. In this paper, we consider, and make recommendations on this matter, by studying a number of inexpensive compact spectrometers in respect of measurement performance and thermal behaviour. Of the studied units, the Avaspec demonstrated the best prospects for the highest time resolution applications, but in the majority of cases, we anticipate users likely preferring the less bulky USB2000+s. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Evaluation of Cartosat-1 Multi-Scale Digital Surface Modelling Over France
Sensors 2009, 9(5), 3269-3288; doi:10.3390/s90503269
Received: 30 March 2009 / Revised: 20 April 2009 / Accepted: 29 April 2009 / Published: 29 April 2009
Cited by 11 | PDF Full-text (3616 KB) | HTML Full-text | XML Full-text
Abstract
On 5 May 2005, the Indian Space Research Organization launched Cartosat-1, the eleventh satellite of its constellation, dedicated to the stereo viewing of the Earth’s surface for terrain modeling and large-scale mapping, from the Satish Dhawan Space Centre (India). In early 2006, [...] Read more.
On 5 May 2005, the Indian Space Research Organization launched Cartosat-1, the eleventh satellite of its constellation, dedicated to the stereo viewing of the Earth’s surface for terrain modeling and large-scale mapping, from the Satish Dhawan Space Centre (India). In early 2006, the Indian Space Research Organization started the Cartosat-1 Scientific Assessment Programme, jointly established with the International Society for Photogrammetry and Remote Sensing. Within this framework, this study evaluated the capabilities of digital surface modeling from Cartosat-1 stereo data for the French test sites of Mausanne les Alpilles and Salon de Provence. The investigation pointed out that for hilly territories it is possible to produce high-resolution digital surface models with a root mean square error less than 7.1 m and a linear error at 90% confidence level less than 9.5 m. The accuracy of the generated digital surface models also fulfilled the requirements of the French Reference 3D®, so Cartosat-1 data may be used to produce or update such kinds of products. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle A Procedure for High Resolution Satellite Imagery Quality Assessment
Sensors 2009, 9(5), 3289-3313; doi:10.3390/s90503289
Received: 10 April 2009 / Revised: 22 April 2009 / Accepted: 5 May 2009 / Published: 5 May 2009
Cited by 17 | PDF Full-text (1735 KB) | HTML Full-text | XML Full-text
Abstract
Data products generated from High Resolution Satellite Imagery (HRSI) are routinely evaluated during the so-called in-orbit test period, in order to verify if their quality fits the desired features and, if necessary, to obtain the image correction parameters to be used at [...] Read more.
Data products generated from High Resolution Satellite Imagery (HRSI) are routinely evaluated during the so-called in-orbit test period, in order to verify if their quality fits the desired features and, if necessary, to obtain the image correction parameters to be used at the ground processing center. Nevertheless, it is often useful to have tools to evaluate image quality also at the final user level. Image quality is defined by some parameters, such as the radiometric resolution and its accuracy, represented by the noise level, and the geometric resolution and sharpness, described by the Modulation Transfer Function (MTF). This paper proposes a procedure to evaluate these image quality parameters; the procedure was implemented in a suitable software and tested on high resolution imagery acquired by the QuickBird, WorldView-1 and Cartosat-1 satellites. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Effects of Anode Flow Field Design on CO2 Bubble Behavior in μDMFC
Sensors 2009, 9(5), 3314-3324; doi:10.3390/s90503314
Received: 15 April 2009 / Revised: 24 April 2009 / Accepted: 27 April 2009 / Published: 6 May 2009
Cited by 4 | PDF Full-text (556 KB) | HTML Full-text | XML Full-text
Abstract
Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC). In this paper, a new type anode structure usingthe concept of the non-equipotent serpentine flow field ( [...] Read more.
Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC). In this paper, a new type anode structure usingthe concept of the non-equipotent serpentine flow field (NESFF) to solve this problem was designed, fabricated and tested. Experiments comparing the μDMFC with and without this type of anode flow field were implemented using a home-made test loop. Results show that the mean-value, amplitude and frequency of the inlet-to-outlet pressure drops in the NESFF is far lower than that in the traditional flow fields at high μDMFC output current. Furthermore, the sequential images of the CO2 bubbles as well as the μDMFC performance with different anode flow field pattern were also investigated, and the conclusions are in accordance with those derived from the pressure drop experiments. Results of this study indicate that the non-equipotent design of the µDMFC anode flow field can effectively mitigate the CO2 clogging in the flow channels, and hence lead to a significant promotion of the μDMFC performance. Full article
Open AccessCommunication A Miniature Probe for Ultrasonic Penetration of a Single Cell
Sensors 2009, 9(5), 3325-3336; doi:10.3390/s90503325
Received: 25 February 2009 / Revised: 27 April 2009 / Accepted: 30 April 2009 / Published: 6 May 2009
Cited by 1 | PDF Full-text (303 KB) | HTML Full-text | XML Full-text
Abstract
Although ultrasound cavitation must be avoided for safe diagnostic applications, the ability of ultrasound to disrupt cell membranes has taken on increasing significance as a method to facilitate drug and gene delivery. A new ultrasonic resonance driving method is introduced to penetrate [...] Read more.
Although ultrasound cavitation must be avoided for safe diagnostic applications, the ability of ultrasound to disrupt cell membranes has taken on increasing significance as a method to facilitate drug and gene delivery. A new ultrasonic resonance driving method is introduced to penetrate rigid wall plant cells or oocytes with springy cell membranes. When a reasonable design is created, ultrasound can gather energy and increase the amplitude factor. Ultrasonic penetration enables exogenous materials to enter cells without damaging them by utilizing instant acceleration. This paper seeks to develop a miniature ultrasonic probe experiment system for cell penetration. A miniature ultrasonic probe is designed and optimized using the Precise Four Terminal Network Method and Finite Element Method (FEM) and an ultrasonic generator to drive the probe is designed. The system was able to successfully puncture a single fish cell. Full article
Open AccessArticle Mechanical-Thermal Noise in Drive-Mode of a Silicon Micro-Gyroscope
Sensors 2009, 9(5), 3357-3375; doi:10.3390/s90503357
Received: 7 April 2009 / Accepted: 6 May 2009 / Published: 7 May 2009
Cited by 6 | PDF Full-text (517 KB) | HTML Full-text | XML Full-text
Abstract
A new closed-loop drive scheme which decouples the phase and the gain of the closed-loop driving system was designed in a Silicon Micro-Gyroscope (SMG). We deduce the system model of closed-loop driving and use stochastic averaging to obtain an approximate “slow” system [...] Read more.
A new closed-loop drive scheme which decouples the phase and the gain of the closed-loop driving system was designed in a Silicon Micro-Gyroscope (SMG). We deduce the system model of closed-loop driving and use stochastic averaging to obtain an approximate “slow” system that clarifies the effect of thermal noise. The effects of mechanical-thermal noise on the driving performance of the SMG, including the noise spectral density of the driving amplitude and frequency, are derived. By calculating and comparing the noise amplitude due to thermal noise both in the opened-loop driving and in the closed-loop driving, we find that the closed-loop driving does not reduce the RMS noise amplitude. We observe that the RMS noise frequency can be reduced by increasing the quality factor and the drive amplitude in the closed-loop driving system. The experiment and simulation validate the feasibility of closed-loop driving and confirm the validity of the averaged equation and its stablility criterion. The experiment and simulation results indicate the electrical noise of closed-loop driving circuitry is bigger than the mechanical-thermal noise and as the driving mass decreases, the mechanical-thermal noise may get bigger than the electrical noise of the closed-loop driving circuitry. Full article
Open AccessArticle Intelligent Foreign Particle Inspection Machine for Injection Liquid Examination Based on Modified Pulse-Coupled Neural Networks
Sensors 2009, 9(5), 3386-3404; doi:10.3390/s90503386
Received: 25 March 2009 / Revised: 22 April 2009 / Accepted: 23 April 2009 / Published: 7 May 2009
Cited by 9 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
A biologically inspired spiking neural network model, called pulse-coupled neural networks (PCNN), has been applied in an automatic inspection machine to detect visible foreign particles intermingled in glucose or sodium chloride injection liquids. Proper mechanisms and improved spin/stop techniques are proposed to [...] Read more.
A biologically inspired spiking neural network model, called pulse-coupled neural networks (PCNN), has been applied in an automatic inspection machine to detect visible foreign particles intermingled in glucose or sodium chloride injection liquids. Proper mechanisms and improved spin/stop techniques are proposed to avoid the appearance of air bubbles, which increases the algorithms’ complexity. Modified PCNN is adopted to segment the difference images, judging the existence of foreign particles according to the continuity and smoothness properties of their moving traces. Preliminarily experimental results indicate that the inspection machine can detect the visible foreign particles effectively and the detection speed, accuracy and correct detection rate also satisfying the needs of medicine preparation. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Determining the Best Sensing Coverage for 2-Dimensional Acoustic Target Tracking
Sensors 2009, 9(5), 3405-3436; doi:10.3390/s90503405
Received: 19 March 2009 / Revised: 15 April 2009 / Accepted: 30 April 2009 / Published: 8 May 2009
Cited by 6 | PDF Full-text (2328 KB) | HTML Full-text | XML Full-text
Abstract
Distributed acoustic target tracking is an important application area of wireless sensor networks. In this paper we use algebraic geometry to formally model 2-dimensional acoustic target tracking and then prove its best degree of required sensing coverage. We present the necessary conditions [...] Read more.
Distributed acoustic target tracking is an important application area of wireless sensor networks. In this paper we use algebraic geometry to formally model 2-dimensional acoustic target tracking and then prove its best degree of required sensing coverage. We present the necessary conditions for three sensing coverage to accurately compute the spatio-temporal information of a target object. Simulations show that 3-coverage accurately locates a target object only in 53% of cases. Using 4-coverage, we present two different methods that yield correct answers in almost all cases and have time and memory usage complexity of Θ(1). Analytic 4-coverage tracking is our first proposed method that solves a simultaneous equation system using the sensing information of four sensor nodes. Redundant answer fusion is our second proposed method that solves at least two sets of simultaneous equations of target tracking using the sensing information of two different sets of three sensor nodes, and fusing the results using a new customized formal majority voter. We prove that 4-coverage guarantees accurate 2-dimensional acoustic target tracking under ideal conditions. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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Open AccessArticle A Butyl Methacrylate Monolithic Column Prepared In-Situ on a Microfluidic Chip and its Applications
Sensors 2009, 9(5), 3437-3446; doi:10.3390/s90503437
Received: 6 February 2009 / Revised: 3 March 2009 / Accepted: 21 April 2009 / Published: 8 May 2009
Cited by 9 | PDF Full-text (465 KB) | HTML Full-text | XML Full-text
Abstract
A butyl methacrylate (BMA) monolithic column was polymerized in-situ with UV irradiation in an ultraviolet transparent PDMS micro-channel on a homemade micro-fluidic chip. Under the optimized conditions and using a typical polymerization mixture consisting of 75% porogenic solvents and 25% monomers, [...] Read more.
A butyl methacrylate (BMA) monolithic column was polymerized in-situ with UV irradiation in an ultraviolet transparent PDMS micro-channel on a homemade micro-fluidic chip. Under the optimized conditions and using a typical polymerization mixture consisting of 75% porogenic solvents and 25% monomers, the BMA monolithic column was obtained as expected. The BET surface area ratio of the BMA monolithic column was 366 m2·g-1. The corresponding SEM images showed that the monolithic column material polymerized in a glass channel was composed of uniform pores and spherical particles with diameters ranging from 3 to 5 μm. The promethazine–luminal–potassium ferricyanide chemiluminescence system was selected for testing the capability of the column. A flow injection analytical technique–chemiluminescence (FIA–CL) system on the microfluidic chip with a BMA monolithic column pretreatment unit was established to determine promethazine. Trace promethazine was enriched by the BMA monolithic column, with more than a 10-fold average enrichment ratio. The proposed method has a linear response concentration range of 1.0×10-8 - 1.0×10-6g·mL-1 and the detection limit was 1.6×10-9g·mL-1. Full article
Open AccessArticle RIDES: Robust Intrusion Detection System for IP-Based Ubiquitous Sensor Networks
Sensors 2009, 9(5), 3447-3468; doi:10.3390/s90503447
Received: 26 February 2009 / Revised: 24 April 2009 / Accepted: 11 May 2009 / Published: 11 May 2009
Cited by 9 | PDF Full-text (358 KB) | HTML Full-text | XML Full-text
Abstract
TheIP-based Ubiquitous Sensor Network (IP-USN) is an effort to build the “Internet of things”. By utilizing IP for low power networks, we can benefit from existing well established tools and technologies of IP networks. Along with many other unresolved issues, securing IP-USN [...] Read more.
TheIP-based Ubiquitous Sensor Network (IP-USN) is an effort to build the “Internet of things”. By utilizing IP for low power networks, we can benefit from existing well established tools and technologies of IP networks. Along with many other unresolved issues, securing IP-USN is of great concern for researchers so that future market satisfaction and demands can be met. Without proper security measures, both reactive and proactive, it is hard to envisage an IP-USN realm. In this paper we present a design of an IDS (Intrusion Detection System) called RIDES (Robust Intrusion DEtection System) for IP-USN. RIDES is a hybrid intrusion detection system, which incorporates both Signature and Anomaly based intrusion detection components. For signature based intrusion detection this paper only discusses the implementation of distributed pattern matching algorithm with the help of signature-code, a dynamically created attack-signature identifier. Other aspects, such as creation of rules are not discussed. On the other hand, for anomaly based detection we propose a scoring classifier based on the SPC (Statistical Process Control) technique called CUSUM charts. We also investigate the settings and their effects on the performance of related parameters for both of the components. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle Micro-Pattern Guided Adhesion of Osteoblasts on Diamond Surfaces
Sensors 2009, 9(5), 3549-3562; doi:10.3390/s90503549
Received: 10 March 2009 / Revised: 7 April 2009 / Accepted: 5 May 2009 / Published: 13 May 2009
Cited by 48 | PDF Full-text (593 KB) | HTML Full-text | XML Full-text
Abstract
Microscopic chemical patterning of diamond surfaces by hydrogen and oxygen surface atoms is used for self-assembly of human osteoblastic cells into micro-arrays. The cell adhesion and assembly is further controlled by concentration of cells (2,500-10,000 cells/cm2)and fetal bovine serum (0-15%). [...] Read more.
Microscopic chemical patterning of diamond surfaces by hydrogen and oxygen surface atoms is used for self-assembly of human osteoblastic cells into micro-arrays. The cell adhesion and assembly is further controlled by concentration of cells (2,500-10,000 cells/cm2)and fetal bovine serum (0-15%). The cells are characterized by fluorescence microscopy of actin fibers and nuclei. The serum protein adsorption is studied by atomic force microscopy (AFM). The cells are arranged selectively on O-terminated patterns into 30-200 μm wide arrays. Higher cell concentrations allow colonization of unfavorable H-terminated regions due to mutual cell communication. There is no cell selectivity without the proteins in the medium. Based on the AFM, the proteins are present on both H- and O-terminated surfaces. Pronounced differences in their thickness, surface roughness, morphology, and phase imagesindicate different conformation of the proteins and explain the cell selectivity. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
Open AccessArticle Deployment Design of Wireless Sensor Network for Simple Multi-Point Surveillance of a Moving Target
Sensors 2009, 9(5), 3563-3585; doi:10.3390/s90503563
Received: 1 April 2009 / Revised: 24 April 2009 / Accepted: 11 May 2009 / Published: 13 May 2009
Cited by 5 | PDF Full-text (313 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we focus on the problem of tracking a moving target in a wireless sensor network (WSN), in which the capability of each sensor is relatively limited, to construct large-scale WSNs at a reasonable cost. We first propose two simple [...] Read more.
In this paper, we focus on the problem of tracking a moving target in a wireless sensor network (WSN), in which the capability of each sensor is relatively limited, to construct large-scale WSNs at a reasonable cost. We first propose two simple multi-point surveillance schemes for a moving target in a WSN and demonstrate that one of the schemes can achieve high tracking probability with low power consumption. In addition, we examine the relationship between tracking probability and sensor density through simulations, and then derive an approximate expression representing the relationship. As the results, we present guidelines for sensor density, tracking probability, and the number of monitoring sensors that satisfy a variety of application demands. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle Monitoring Animal Behaviour and Environmental Interactions Using Wireless Sensor Networks, GPS Collars and Satellite Remote Sensing
Sensors 2009, 9(5), 3586-3603; doi:10.3390/s90503586
Received: 9 April 2009 / Revised: 4 May 2009 / Accepted: 13 May 2009 / Published: 13 May 2009
Cited by 75 | PDF Full-text (1250 KB) | HTML Full-text | XML Full-text
Abstract
Remote monitoring of animal behaviour in the environment can assist in managing both the animal and its environmental impact. GPS collars which record animal locations with high temporal frequency allow researchers to monitor both animal behaviour and interactions with the environment. These [...] Read more.
Remote monitoring of animal behaviour in the environment can assist in managing both the animal and its environmental impact. GPS collars which record animal locations with high temporal frequency allow researchers to monitor both animal behaviour and interactions with the environment. These ground-based sensors can be combined with remotely-sensed satellite images to understand animal-landscape interactions. The key to combining these technologies is communication methods such as wireless sensor networks (WSNs). We explore this concept using a case-study from an extensive cattle enterprise in northern Australia and demonstrate the potential for combining GPS collars and satellite images in a WSN to monitor behavioural preferences and social behaviour of cattle. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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Open AccessArticle Metal Ion Enhanced Charge Transfer in a Terpyridine-bis-Pyrene System
Sensors 2009, 9(5), 3604-3626; doi:10.3390/s90503604
Received: 7 April 2009 / Revised: 8 May 2009 / Accepted: 12 May 2009 / Published: 13 May 2009
Cited by 13 | PDF Full-text (488 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4'-phenyl-2,2':6',2''-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both [...] Read more.
The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4'-phenyl-2,2':6',2''-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both charge transfer (CT) absorption and CT emission. Furthermore, the study of the zinc complex as well as the bis-protonated form shows an enhancement of the electron transfer character of the system, by an increase of the acceptor strength. This is accompanied by a large increase of the non-radiative processes. With sub-nanosecond transient absorption spectroscopy, the CT state, consisting of the pyrene radical cation and the terpyridine radical anion, has been detected. At room temperature, the study of the nanosecond transient absorption spectra reveals the formation of a low-lying triplet excited state that we attribute to the pyrene moiety through which the CT state decays. At 77K, the absence of the terpyridine triplet emission also suggests the population of a low-lying triplet state of the pyrene unit. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Evaluation of Cholinesterase Activities During in Vivo Intoxication Using an Electrochemical Sensor Strip – Correlation With Intoxication Symptoms
Sensors 2009, 9(5), 3627-3634; doi:10.3390/s90503627
Received: 20 April 2009 / Revised: 10 May 2009 / Accepted: 13 May 2009 / Published: 14 May 2009
Cited by 4 | PDF Full-text (45 KB) | HTML Full-text | XML Full-text
Abstract
Cholinesterase activity in blood of laboratory rats was monitored. Rats were intoxicated with paraoxon at dosis of 0 – 65 – 125 – 170 – 250 – 500 nmol. The 250 nmol dose was found to be the LD50. An [...] Read more.
Cholinesterase activity in blood of laboratory rats was monitored. Rats were intoxicated with paraoxon at dosis of 0 – 65 – 125 – 170 – 250 – 500 nmol. The 250 nmol dose was found to be the LD50. An electrochemical sensor was found useful to provide information about cholinesterase activity. The decrease of cholinesterase activity was correlated to intoxication symptoms and mortality level. It was found that the symptoms of intoxication are not observed while at least 50% of cholinesterase activity in blood remains. The minimal cholinesterase activity essential to survival is around 10%, when compared with the initial state. No changes in levels of low moleculary weight antioxidants were observed. Full article
Open AccessArticle Metadata behind the Interoperability of Wireless Sensor Networks
Sensors 2009, 9(5), 3635-3651; doi:10.3390/s90503635
Received: 17 April 2009 / Revised: 8 May 2009 / Accepted: 14 May 2009 / Published: 14 May 2009
Cited by 13 | PDF Full-text (126 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks (WSNs) produce changes of status that are frequent, dynamic and unpredictable, and cannot be represented using a linear cause-effect approach. Consequently, a new approach is needed to handle these changes in order to support dynamic interoperability. Our approach is [...] Read more.
Wireless Sensor Networks (WSNs) produce changes of status that are frequent, dynamic and unpredictable, and cannot be represented using a linear cause-effect approach. Consequently, a new approach is needed to handle these changes in order to support dynamic interoperability. Our approach is to introduce the notion of context as an explicit representation of changes of a WSN status inferred from metadata elements, which in turn, leads towards a decision-making process about how to maintain dynamic interoperability. This paper describes the developed context model to represent and reason over different WSN status based on four types of contexts, which have been identified as sensing, node, network and organisational contexts. The reasoning has been addressed by developing contextualising and bridges rules. As a result, we were able to demonstrate how contextualising rules have been used to reason on changes of WSN status as a first step towards maintaining dynamic interoperability. Full article
(This article belongs to the Special Issue Workshop Sensing A Changing World)
Open AccessArticle Digitally Programmable Analogue Circuits for Sensor Conditioning Systems
Sensors 2009, 9(5), 3652-3665; doi:10.3390/s90503652
Received: 16 April 2009 / Revised: 12 May 2009 / Accepted: 13 May 2009 / Published: 14 May 2009
Cited by 5 | PDF Full-text (320 KB) | HTML Full-text | XML Full-text
Abstract
This work presents two current-mode integrated circuits designed for sensor signal preprocessing in embedded systems. The proposed circuits have been designed to provide good signal transfer and fulfill their function, while minimizing the load effects due to building complex conditioning architectures. The [...] Read more.
This work presents two current-mode integrated circuits designed for sensor signal preprocessing in embedded systems. The proposed circuits have been designed to provide good signal transfer and fulfill their function, while minimizing the load effects due to building complex conditioning architectures. The processing architecture based on the proposed building blocks can be reconfigured through digital programmability. Thus, sensor useful range can be expanded, changes in the sensor operation can be compensated for and furthermore, undesirable effects such as device mismatching and undesired physical magnitudes sensor sensibilities are reduced. The circuits were integrated using a 0.35 mm standard CMOS process. Experimental measurements, load effects and a study of two different tuning strategies are presented. From these results, system performance is tested in an application which entails extending the linear range of a magneto-resistive sensor. Circuit area, average power consumption and programmability features allow these circuits to be included in embedded sensing systems as a part of the analogue conditioning components. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
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Open AccessArticle Optimal Design and Operation for a No-Moving-Parts-Valve (NMPV) Micro-Pump with a Diffuser Width of 500 µm
Sensors 2009, 9(5), 3666-3678; doi:10.3390/s90503666
Received: 28 March 2009 / Revised: 28 April 2009 / Accepted: 15 May 2009 / Published: 15 May 2009
Cited by 3 | PDF Full-text (2177 KB) | HTML Full-text | XML Full-text
Abstract
A no-moving-parts-valve (NMPV) with a diffuser width of D = 500 microns was investigated in this study by numerical simulations at Reynolds numbers, ReD, ranging from 20 to 75, and expansion valve angles ranging from 30° < θ1 < 57° and 110° < θ2 < 120°. The D p,i value, 1.02 < D p,i < 1.14, is larger within the proposed range of the expansion valve angles. A flow channel structure with a depth of 500 micron is manufactured using yellow light lithography in this study. From prior analyses and experiments, it is found that piezoelectric films work better at a buzz driving frequency of f < 30Hz and the best operating frequency is at a driving frequency of f = 10Hz because it produces the largest net flow. In addition, the expansion angles θ1 = 30° and θ2 = 120° are the best expansion angles because they produce the largest net flow. These related results are very helpful for the actual design of no-moving-parts-valve micro-pump. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Vehicle Based Laser Range Finding in Crops
Sensors 2009, 9(5), 3679-3694; doi:10.3390/s90503679
Received: 27 August 2008 / Accepted: 28 October 2008 / Published: 15 May 2009
Cited by 4 | PDF Full-text (1887 KB) | HTML Full-text | XML Full-text
Abstract
Laser rangefinders and laser scanners are widely used for industrial purposes and for remote sensing. In agriculture information about crop parameters like volume, height, and density can support the optimisation of production processes. In scientific papers the measurement of these parameters by [...] Read more.
Laser rangefinders and laser scanners are widely used for industrial purposes and for remote sensing. In agriculture information about crop parameters like volume, height, and density can support the optimisation of production processes. In scientific papers the measurement of these parameters by low cost laser rangefinders with one echo has been presented for short ranges. Because the cross section area of the beam increases with the measuring range, it can be expected that laser rangefinders will have a reduced measuring accuracy in small sized crops and when measuring far distances. These problems are caused by target areas smaller than the beam and by the beam striking the edges of crop objects. Lab tests under defined conditions and a real field test were performed to assess the measuring properties under such difficult conditions of a chosen low cost sensor. Based on lab tests it was shown that the accuracy was reduced, but the successful use of the sensor under field conditions demonstrated the potential to meet the demands for agricultural applications. Insights resulting from investigations made in the paper contribute to facilitating the choice or the development of laser rangefinder sensors for vehicle based measurement of crop parameters for optimisation of production processes. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle A Hybrid Stochastic Approach for Self-Location of Wireless Sensors in Indoor Environments
Sensors 2009, 9(5), 3695-3712; doi:10.3390/s90503695
Received: 2 April 2009 / Revised: 4 May 2009 / Accepted: 14 May 2009 / Published: 15 May 2009
Cited by 32 | PDF Full-text (468 KB) | HTML Full-text | XML Full-text
Abstract
Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location [...] Read more.
Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location estimation because of the issues arising in the indoor environment. Two different approaches had been proposed using WLAN location systems: on the one hand, the so-called deductive methods take into account the physical properties of signal propagation. These systems require a propagation model, an environment map, and the position of the radio-stations. On the other hand, the so-called inductive methods require a previous training phase where the system learns the received signal strength (RSS) in each location. This phase can be very time consuming. This paper proposes a new stochastic approach which is based on a combination of deductive and inductive methods whereby wireless sensors could determine their positions using WLAN technology inside a floor of a building. Our goal is to reduce the training phase in an indoor environment, but, without an loss of precision. Finally, we compare the measurements taken using our proposed method in a real environment with the measurements taken by other developed systems. Comparisons between the proposed system and other hybrid methods are also provided. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle Performance Analysis of the SIFT Operator for Automatic Feature Extraction and Matching in Photogrammetric Applications
Sensors 2009, 9(5), 3745-3766; doi:10.3390/s90503745
Received: 21 April 2009 / Revised: 12 May 2009 / Accepted: 18 May 2009 / Published: 18 May 2009
Cited by 62 | PDF Full-text (669 KB) | HTML Full-text | XML Full-text
Abstract
In the photogrammetry field, interest in region detectors, which are widely used in Computer Vision, is quickly increasing due to the availability of new techniques. Images acquired by Mobile Mapping Technology, Oblique Photogrammetric Cameras or Unmanned Aerial Vehicles do not observe normal [...] Read more.
In the photogrammetry field, interest in region detectors, which are widely used in Computer Vision, is quickly increasing due to the availability of new techniques. Images acquired by Mobile Mapping Technology, Oblique Photogrammetric Cameras or Unmanned Aerial Vehicles do not observe normal acquisition conditions. Feature extraction and matching techniques, which are traditionally used in photogrammetry, are usually inefficient for these applications as they are unable to provide reliable results under extreme geometrical conditions (convergent taking geometry, strong affine transformations, etc.) and for bad-textured images. A performance analysis of the SIFT technique in aerial and close-range photogrammetric applications is presented in this paper. The goal is to establish the suitability of the SIFT technique for automatic tie point extraction and approximate DSM (Digital Surface Model) generation. First, the performances of the SIFT operator have been compared with those provided by feature extraction and matching techniques used in photogrammetry. All these techniques have been implemented by the authors and validated on aerial and terrestrial images. Moreover, an auto-adaptive version of the SIFT operator has been developed, in order to improve the performances of the SIFT detector in relation to the texture of the images. The Auto-Adaptive SIFT operator (A2 SIFT) has been validated on several aerial images, with particular attention to large scale aerial images acquired using mini-UAV systems. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessArticle Novel Oversampling Technique for Improving Signal-to-Quantization Noise Ratio on Accelerometer-Based Smart Jerk Sensors in CNC Applications
Sensors 2009, 9(5), 3767-3789; doi:10.3390/s90503767
Received: 8 May 2009 / Revised: 14 May 2009 / Accepted: 19 May 2009 / Published: 19 May 2009
Cited by 16 | PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
Jerk monitoring, defined as the first derivative of acceleration, has become a major issue in computerized numeric controlled (CNC) machines. Several works highlight the necessity of measuring jerk in a reliable way for improving production processes. Nowadays, the computation of jerk is [...] Read more.
Jerk monitoring, defined as the first derivative of acceleration, has become a major issue in computerized numeric controlled (CNC) machines. Several works highlight the necessity of measuring jerk in a reliable way for improving production processes. Nowadays, the computation of jerk is done by finite differences of the acceleration signal, computed at the Nyquist rate, which leads to low signal-to-quantization noise ratio (SQNR) during the estimation. The novelty of this work is the development of a smart sensor for jerk monitoring from a standard accelerometer, which has improved SQNR. The proposal is based on oversampling techniques that give a better estimation of jerk than that produced by a Nyquist-rate differentiator. Simulations and experimental results are presented to show the overall methodology performance. Full article
Open AccessArticle Design of a Sensor Based on Plastic Optical Fibre (POF) to Measure Fluid Flow and Turbidity
Sensors 2009, 9(5), 3790-3800; doi:10.3390/s90503790
Received: 27 April 2009 / Revised: 14 May 2009 / Accepted: 15 May 2009 / Published: 19 May 2009
Cited by 10 | PDF Full-text (336 KB) | HTML Full-text | XML Full-text
Abstract
Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it [...] Read more.
Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it can be used as a sensor for this parameter. There are many strong arguments for the use of POFs as sensors. In addition to being easy to handle and low cost, they demonstrate advantages common to all multimode optical fibres. These specifically include flexibility, small size, good electromagnetic compatibility behaviour, and in general, the possibility of measuring any phenomenon without physically interacting with it. In this paper, a sensor based on POF is designed and analysed with the aim of measuring the volume and turbidity of a low viscosity fluid, in this case water, as it passes through a pipe. A comparative study with a commercial sensor is provided to validate the proven flow measurement. Likewise, turbidity is measured using different colour dyes. Finally, this paper will present the most significant results and conclusions from all the tests which are carried out. Full article
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Open AccessArticle Nonlinear Dynamics and Chaos of Microcantilever-Based TM-AFMs with Squeeze Film Damping Effects
Sensors 2009, 9(5), 3854-3874; doi:10.3390/s90503854
Received: 27 March 2009 / Revised: 23 April 2009 / Accepted: 13 May 2009 / Published: 20 May 2009
Cited by 16 | PDF Full-text (522 KB) | HTML Full-text | XML Full-text
Abstract
In Atomic force microscope (AFM) examination of a vibrating microcantilever, the nonlinear tip-sample interaction would greatly influence the dynamics of the cantilever. In this paper, the nonlinear dynamics and chaos of a tip-sample dynamic system being run in the tapping mode (TM) [...] Read more.
In Atomic force microscope (AFM) examination of a vibrating microcantilever, the nonlinear tip-sample interaction would greatly influence the dynamics of the cantilever. In this paper, the nonlinear dynamics and chaos of a tip-sample dynamic system being run in the tapping mode (TM) were investigated by considering the effects of hydrodynamic loading and squeeze film damping. The microcantilever was modeled as a spring-mass-damping system and the interaction between the tip and the sample was described by the Lennard-Jones (LJ) potential. The fundamental frequency and quality factor were calculated from the transient oscillations of the microcantilever vibrating in air. Numerical simulations were carried out to study the coupled nonlinear dynamic system using the bifurcation diagram, Poincaré maps, largest Lyapunov exponent, phase portraits and time histories. Results indicated the occurrence of periodic and chaotic motions and provided a comprehensive understanding of the hydrodynamic loading of microcantilevers. It was demonstrated that the coupled dynamic system will experience complex nonlinear oscillation as the system parameters change and the effect of squeeze film damping is not negligible on the micro-scale. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Polarised Multiangular Reflectance Measurements Using the Finnish Geodetic Institute Field Goniospectrometer
Sensors 2009, 9(5), 3891-3907; doi:10.3390/s90503891
Received: 15 April 2009 / Revised: 15 May 2009 / Accepted: 21 May 2009 / Published: 22 May 2009
Cited by 29 | PDF Full-text (616 KB) | HTML Full-text | XML Full-text
Abstract
The design, operation, and properties of the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) are presented. FIGIFIGO is a portable instrument for the measurement of surface Bidirectional Reflectance Factor (BRF) for samples with diameters of 10 – 50 cm. A set of polarising [...] Read more.
The design, operation, and properties of the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) are presented. FIGIFIGO is a portable instrument for the measurement of surface Bidirectional Reflectance Factor (BRF) for samples with diameters of 10 – 50 cm. A set of polarising optics enable the measurement of linearly polarised BRF over the full solar spectrum (350 – 2,500 nm). FIGIFIGO is designed mainly for field operation using sunlight, but operation in a laboratory environment is also possible. The acquired BRF have an accuracy of 1 – 5% depending on wavelength, sample properties, and measurement conditions. The angles are registered at accuracies better than 2°. During 2004 – 2008, FIGIFIGO has been used in the measurement of over 150 samples, all around northern Europe. The samples concentrate mostly on boreal forest understorey, snow, urban surfaces, and reflectance calibration surfaces. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Dynamic Hierarchical Sleep Scheduling for Wireless Ad-Hoc Sensor Networks
Sensors 2009, 9(5), 3908-3941; doi:10.3390/s90503908
Received: 18 March 2009 / Revised: 29 April 2009 / Accepted: 20 May 2009 / Published: 25 May 2009
Cited by 5 | PDF Full-text (785 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents two scheduling management schemes for wireless sensor networks, which manage the sensors by utilizing the hierarchical network structure and allocate network resources efficiently. A local criterion is used to simultaneously establish the sensing coverage and connectivity such that dynamic [...] Read more.
This paper presents two scheduling management schemes for wireless sensor networks, which manage the sensors by utilizing the hierarchical network structure and allocate network resources efficiently. A local criterion is used to simultaneously establish the sensing coverage and connectivity such that dynamic cluster-based sleep scheduling can be achieved. The proposed schemes are simulated and analyzed to abstract the network behaviors in a number of settings. The experimental results show that the proposed algorithms provide efficient network power control and can achieve high scalability in wireless sensor networks. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle A Heterogeneous Wireless Identification Network for the Localization of Animals Based on Stochastic Movements
Sensors 2009, 9(5), 3942-3957; doi:10.3390/s90503942
Received: 27 April 2009 / Revised: 14 May 2009 / Accepted: 22 May 2009 / Published: 25 May 2009
Cited by 11 | PDF Full-text (440 KB) | HTML Full-text | XML Full-text
Abstract
The improvement in the transmission range in wireless applications without the use of batteries remains a significant challenge in identification applications. In this paper, we describe a heterogeneous wireless identification network mostly powered by kinetic energy, which allows the localization of animals [...] Read more.
The improvement in the transmission range in wireless applications without the use of batteries remains a significant challenge in identification applications. In this paper, we describe a heterogeneous wireless identification network mostly powered by kinetic energy, which allows the localization of animals in open environments. The system relies on radio communications and a global positioning system. It is made up of primary and secondary nodes. Secondary nodes are kinetic-powered and take advantage of animal movements to activate the node and transmit a specific identifier, reducing the number of batteries of the system. Primary nodes are battery-powered and gather secondary-node transmitted information to provide it, along with position and time data, to a final base station in charge of the animal monitoring. The system allows tracking based on contextual information obtained from statistical data. Full article
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Open AccessArticle Using Reputation Systems and Non-Deterministic Routing to Secure Wireless Sensor Networks
Sensors 2009, 9(5), 3958-3980; doi:10.3390/s90503958
Received: 9 April 2009 / Revised: 4 May 2009 / Accepted: 19 May 2009 / Published: 25 May 2009
Cited by 10 | PDF Full-text (838 KB) | HTML Full-text | XML Full-text
Abstract
Security in wireless sensor networks is difficult to achieve because of the resource limitations of the sensor nodes. We propose a trust-based decision framework for wireless sensor networks coupled with a non-deterministic routing protocol. Both provide a mechanism to effectively detect and [...] Read more.
Security in wireless sensor networks is difficult to achieve because of the resource limitations of the sensor nodes. We propose a trust-based decision framework for wireless sensor networks coupled with a non-deterministic routing protocol. Both provide a mechanism to effectively detect and confine common attacks, and, unlike previous approaches, allow bad reputation feedback to the network. This approach has been extensively simulated, obtaining good results, even for unrealistically complex attack scenarios. Full article
Open AccessArticle Multi-Objective Differential Evolution for Automatic Clustering with Application to Micro-Array Data Analysis
Sensors 2009, 9(5), 3981-4004; doi:10.3390/s90503981
Received: 1 April 2009 / Revised: 19 May 2009 / Accepted: 22 May 2009 / Published: 25 May 2009
Cited by 15 | PDF Full-text (484 KB) | HTML Full-text | XML Full-text
Abstract
This paper applies the Differential Evolution (DE) algorithm to the task of automatic fuzzy clustering in a Multi-objective Optimization (MO) framework. It compares the performances of two multi-objective variants of DE over the fuzzy clustering problem, where two conflicting fuzzy validity indices [...] Read more.
This paper applies the Differential Evolution (DE) algorithm to the task of automatic fuzzy clustering in a Multi-objective Optimization (MO) framework. It compares the performances of two multi-objective variants of DE over the fuzzy clustering problem, where two conflicting fuzzy validity indices are simultaneously optimized. The resultant Pareto optimal set of solutions from each algorithm consists of a number of non-dominated solutions, from which the user can choose the most promising ones according to the problem specifications. A real-coded representation of the search variables, accommodating variable number of cluster centers, is used for DE. The performances of the multi-objective DE-variants have also been contrasted to that of two most well-known schemes of MO clustering, namely the Non Dominated Sorting Genetic Algorithm (NSGA II) and Multi-Objective Clustering with an unknown number of Clusters K (MOCK). Experimental results using six artificial and four real life datasets of varying range of complexities indicate that DE holds immense promise as a candidate algorithm for devising MO clustering schemes. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Guided Wave and Damage Detection in Composite Laminates Using Different Fiber Optic Sensors
Sensors 2009, 9(5), 4005-4021; doi:10.3390/s90504005
Received: 8 April 2009 / Revised: 18 May 2009 / Accepted: 21 May 2009 / Published: 25 May 2009
Cited by 24 | PDF Full-text (500 KB) | HTML Full-text | XML Full-text
Abstract
Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) [...] Read more.
Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH0) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)

Review

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Open AccessReview Detection of Gaseous Plumes using Basis Vectors
Sensors 2009, 9(5), 3205-3217; doi:10.3390/s90503205
Received: 9 January 2009 / Revised: 19 March 2009 / Accepted: 15 April 2009 / Published: 27 April 2009
Cited by 2 | PDF Full-text (2324 KB) | HTML Full-text | XML Full-text
Abstract
Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. There are several methods currently being used to detect plumes. They can be grouped into two categories: those that use a chemical spectral library and those that [...] Read more.
Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. There are several methods currently being used to detect plumes. They can be grouped into two categories: those that use a chemical spectral library and those that don’t. The approaches that use chemical libraries include physics-based least squares methods (matched filter). They are “optimal” only if the plume chemical is actually in the search library but risk missing chemicals not in the library. The methods that don’t use a chemical spectral library are based on a statistical or data analytical transformation applied to the data. These include principle components, independent components, entropy, Fourier transform, and others. These methods do not explicitly take advantage of the physics of the signal formulation process and therefore don’t exploit all available information in the data. This paper describes generalized least squares detection using gas spectra, presents a new detection method using basis vectors, and compares detection images resulting from applying both methods to synthetic hyperspectral data. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessReview Methodology and Significance of Microsensor-based Oxygen Mapping in Plant Seeds – an Overview
Sensors 2009, 9(5), 3218-3227; doi:10.3390/s90503218
Received: 17 March 2009 / Revised: 24 April 2009 / Accepted: 27 April 2009 / Published: 27 April 2009
Cited by 20 | PDF Full-text (857 KB) | HTML Full-text | XML Full-text
Abstract
Oxygen deficiency is commonplace in seeds, and limits both their development and their germination. It is, therefore, of considerable relevance to crop production. While the underlying physiological basis of seed hypoxia has been known for some time, the lack of any experimental [...] Read more.
Oxygen deficiency is commonplace in seeds, and limits both their development and their germination. It is, therefore, of considerable relevance to crop production. While the underlying physiological basis of seed hypoxia has been known for some time, the lack of any experimental means of measuring the global or localized oxygen concentration within the seed has hampered further progress in this research area. The development of oxygen-sensitive microsensors now offers the capability to determine the localized oxygen status within a seed, and to study its dynamic adjustment both to changes in the ambient environment, and to the seed's developmental stage. This review illustrates the use of oxygen microsensors in seed research, and presents an overview of existing data with an emphasis on crop species. Oxygen maps, both static and dynamic, should serve to increase our basic understanding of seed physiology, as well as to facilitate upcoming breeding and biotechnology-based approaches for crop improvement. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessReview Optical and Electronic NOx Sensors for Applications in Mechatronics
Sensors 2009, 9(5), 3337-3356; doi:10.3390/s90503337
Received: 13 March 2009 / Revised: 24 April 2009 / Accepted: 6 May 2009 / Published: 6 May 2009
Cited by 10 | PDF Full-text (3046 KB) | HTML Full-text | XML Full-text
Abstract
Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active [...] Read more.
Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview A Real-Time Spectroscopic Sensor for Monitoring Laser Welding Processes
Sensors 2009, 9(5), 3376-3385; doi:10.3390/s90503376
Received: 4 March 2009 / Revised: 28 April 2009 / Accepted: 29 April 2009 / Published: 7 May 2009
Cited by 28 | PDF Full-text (317 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we report on the development of a sensor for real time monitoring of laser welding processes based on spectroscopic techniques. The system is based on the acquisition of the optical spectra emitted from the laser generated plasma plume and [...] Read more.
In this paper we report on the development of a sensor for real time monitoring of laser welding processes based on spectroscopic techniques. The system is based on the acquisition of the optical spectra emitted from the laser generated plasma plume and their use to implement an on-line algorithm for both the calculation of the plasma electron temperature and the analysis of the correlations between selected spectral lines. The sensor has been patented and it is currently available on the market. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview Feasibility Studies on Si-Based Biosensors
Sensors 2009, 9(5), 3469-3490; doi:10.3390/s90503469
Received: 20 February 2009 / Revised: 6 April 2009 / Accepted: 9 April 2009 / Published: 11 May 2009
Cited by 12 | PDF Full-text (800 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this paperis to summarize the efforts carried out so far in the fabrication of Si-based biosensors by a team of researchers in Catania, Italy. This work was born as a collaboration between the Catania section of the Microelectronic and [...] Read more.
The aim of this paperis to summarize the efforts carried out so far in the fabrication of Si-based biosensors by a team of researchers in Catania, Italy. This work was born as a collaboration between the Catania section of the Microelectronic and Microsystem Institute (IMM) of the CNR, the Surfaces and Interfaces laboratory (SUPERLAB) of the Consorzio Catania Ricerche and two departments at the University of Catania: the Biomedical Science and the Biological Chemistry and Molecular Biology Departments. The first goal of our study was the definition and optimization of an immobilization protocol capable of bonding the biological sensing element on a Si-based surface via covalent chemical bonds. We chose SiO2 as the anchoring surface due to its biocompatibility and extensive presence in microelectronic devices. The immobilization protocol was tested and optimized, introducing a new step, oxide activation, using techniques compatible with microelectronic processing. The importance of the added step is described by the experimental results. We also tested different biological molecule concentrations in the immobilization solutions and the effects on the immobilized layer. Finally a MOS-like structure was designed and fabricated to test an electrical transduction mechanism. The results obtained so far and the possible evolution of the research field are described in this review paper. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications
Sensors 2009, 9(5), 3491-3526; doi:10.3390/s90503491
Received: 26 March 2009 / Revised: 5 May 2009 / Accepted: 8 May 2009 / Published: 12 May 2009
Cited by 159 | PDF Full-text (1592 KB) | HTML Full-text | XML Full-text
Abstract
Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe [...] Read more.
Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview Laser‐Self‐Mixing Interferometry for Mechatronics Applications
Sensors 2009, 9(5), 3527-3548; doi:10.3390/s90503527
Received: 16 March 2009 / Revised: 21 April 2009 / Accepted: 6 May 2009 / Published: 12 May 2009
Cited by 20 | PDF Full-text (805 KB) | HTML Full-text | XML Full-text
Abstract
We report on the development of an all-interferometric optomechatronic sensor for the detection of multi-degrees-of-freedom displacements of a remote target. The prototype system exploits the self-mixing technique and consists only of a laser head, equipped with six laser sources, and a suitably [...] Read more.
We report on the development of an all-interferometric optomechatronic sensor for the detection of multi-degrees-of-freedom displacements of a remote target. The prototype system exploits the self-mixing technique and consists only of a laser head, equipped with six laser sources, and a suitably designed reflective target. The feasibility of the system was validated experimentally for both single or multi-degrees-of-freedom measurements, thus demonstrating a simple and inexpensive alternative to costly and bulky existing systems. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview Nucleic Acid-based Detection of Bacterial Pathogens Using Integrated Microfluidic Platform Systems
Sensors 2009, 9(5), 3713-3744; doi:10.3390/s90503713
Received: 9 April 2009 / Revised: 12 May 2009 / Accepted: 18 May 2009 / Published: 18 May 2009
Cited by 38 | PDF Full-text (1090 KB) | HTML Full-text | XML Full-text
Abstract
The advent of nucleic acid-based pathogen detection methods offers increased sensitivity and specificity over traditional microbiological techniques, driving the development of portable, integrated biosensors. The miniaturization and automation of integrated detection systems presents a significant advantage for rapid, portable field-based testing. In [...] Read more.
The advent of nucleic acid-based pathogen detection methods offers increased sensitivity and specificity over traditional microbiological techniques, driving the development of portable, integrated biosensors. The miniaturization and automation of integrated detection systems presents a significant advantage for rapid, portable field-based testing. In this review, we highlight current developments and directions in nucleic acid-based micro total analysis systems for the detection of bacterial pathogens. Recent progress in the miniaturization of microfluidic processing steps for cell capture, DNA extraction and purification, polymerase chain reaction, and product detection are detailed. Discussions include strategies and challenges for implementation of an integrated portable platform. Full article
(This article belongs to the Special Issue Pathogen Sensors)
Open AccessReview A Review of Current Methodologies for Regional Evapotranspiration Estimation from Remotely Sensed Data
Sensors 2009, 9(5), 3801-3853; doi:10.3390/s90503801
Received: 15 March 2009 / Revised: 27 April 2009 / Accepted: 18 May 2009 / Published: 19 May 2009
Cited by 184 | PDF Full-text (380 KB) | HTML Full-text | XML Full-text
Abstract
An overview of the commonly applied evapotranspiration (ET) models using remotely sensed data is given to provide insight into the estimation of ET on a regional scale from satellite data. Generally, these models vary greatly in inputs, main assumptions and accuracy of [...] Read more.
An overview of the commonly applied evapotranspiration (ET) models using remotely sensed data is given to provide insight into the estimation of ET on a regional scale from satellite data. Generally, these models vary greatly in inputs, main assumptions and accuracy of results, etc. Besides the generally used remotely sensed multi-spectral data from visible to thermal infrared bands, most remotely sensed ET models, from simplified equations models to the more complex physically based two-source energy balance models, must rely to a certain degree on ground-based auxiliary measurements in order to derive the turbulent heat fluxes on a regional scale. We discuss the main inputs, assumptions, theories, advantages and drawbacks of each model. Moreover, approaches to the extrapolation of instantaneous ET to the daily values are also briefly presented. In the final part, both associated problems and future trends regarding these remotely sensed ET models were analyzed to objectively show the limitations and promising aspects of the estimation of regional ET based on remotely sensed data and ground-based measurements. Full article
(This article belongs to the Section Remote Sensors)
Open AccessReview Sun Tracking Systems: A Review
Sensors 2009, 9(5), 3875-3890; doi:10.3390/s90503875
Received: 14 April 2009 / Revised: 6 May 2009 / Accepted: 15 May 2009 / Published: 20 May 2009
Cited by 68 | PDF Full-text (824 KB) | HTML Full-text | XML Full-text
Abstract
The output power produced by high-concentration solar thermal and photovoltaic systems is directly related to the amount of solar energy acquired by the system, and it is therefore necessary to track the sun’s position with a high degree of accuracy. Many systems [...] Read more.
The output power produced by high-concentration solar thermal and photovoltaic systems is directly related to the amount of solar energy acquired by the system, and it is therefore necessary to track the sun’s position with a high degree of accuracy. Many systems have been proposed to facilitate this task over the past 20 years. Accordingly, this paper commences by providing a high level overview of the sun tracking system field and then describes some of the more significant proposals for closed-loop and open-loop types of sun tracking systems. Full article
(This article belongs to the Special Issue Sensor Algorithms)

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