Sensors

1941 KiB

Open AccessArticle

Techno-Economic Analysis of Solar Water Heating Systems inTurkey

by Can Ertekin, Recep Kulcu and Fatih Evrendilek

Sensors 2008, 8(2), 1252-1277; https://doi.org/10.3390/s8021252 - 25 Feb 2008

Cited by 20 | Viewed by 14542

In this study, solar water heater was investigated using meteorological and geographical data of 129 sites over Turkey. Three different collector types were compared in terms of absorber material (copper, galvanized sheet and selective absorber). Energy requirement for water heating, collector performances, and [...] Read more.

In this study, solar water heater was investigated using meteorological and geographical data of 129 sites over Turkey. Three different collector types were compared in terms of absorber material (copper, galvanized sheet and selective absorber). Energy requirement for water heating, collector performances, and economical indicators were calculated with formulations using observed data. Results showed that selective absorbers were most appropriate in terms of coverage rate of energy requirement for water-heating all over Turkey. The prices of selective, copper and galvanized absorber type’s heating systems in Turkey were 740.49, 615.69 and 490.89 USD, respectively. While payback periods (PBPs) of the galvanized absorber were lower, net present values (NPVs) of the selective absorber were higher than the rest. Copper absorber type collectors did not appear to be appropriate based on economical indicators. Full article

(This article belongs to the Special Issue Spatio-Temporal Modeling of Solar Radiation, Climate and Biogeochemical Cycles)

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224 KiB

Open AccessArticle

Range and Velocity Estimation of Moving Targets Using Multiple Stepped-frequency Pulse Trains

by Gang Li, Huadong Meng, Xiang-Gen Xia and Ying-Ning Peng

Sensors 2008, 8(2), 1343-1350; https://doi.org/10.3390/s8021343 - 22 Feb 2008

Cited by 39 | Viewed by 11141

Abstract

Range and velocity estimation of moving targets using conventional steppedfrequencypulse radar may suffer from the range-Doppler coupling and the phasewrapping. To overcome these problems, this paper presents a new radar waveform namedmultiple stepped-frequency pulse trains and proposes a new algorithm. It is shown [...] Read more.

Range and velocity estimation of moving targets using conventional steppedfrequencypulse radar may suffer from the range-Doppler coupling and the phasewrapping. To overcome these problems, this paper presents a new radar waveform namedmultiple stepped-frequency pulse trains and proposes a new algorithm. It is shown that byusing multiple stepped-frequency pulse trains and the robust phase unwrapping theorem(RPUT), both of the range-Doppler coupling and the phase wrapping can be robustlyresolved, and accordingly, the range and the velocity of a moving target can be accuratelyestimated. Full article

(This article belongs to the Special Issue Aerospace Sensor Systems)

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2793 KiB

Open AccessArticle

The Successive Projection Algorithm (SPA), an Algorithm with a Spatial Constraint for the Automatic Search of Endmembers in Hyperspectral Data

by Jinkai Zhang, Benoit Rivard and D. M. Rogge

Sensors 2008, 8(2), 1321-1342; https://doi.org/10.3390/s8021321 - 22 Feb 2008

Cited by 80 | Viewed by 15339

Abstract

Spectral mixing is a problem inherent to remote sensing data and results in fewimage pixel spectra representing "pure" targets. Linear spectral mixture analysis isdesigned to address this problem and it assumes that the pixel-to-pixel variability in ascene results from varying proportions of spectral [...] Read more.

Spectral mixing is a problem inherent to remote sensing data and results in fewimage pixel spectra representing "pure" targets. Linear spectral mixture analysis isdesigned to address this problem and it assumes that the pixel-to-pixel variability in ascene results from varying proportions of spectral endmembers. In this paper we present adifferent endmember-search algorithm called the Successive Projection Algorithm (SPA).SPA builds on convex geometry and orthogonal projection common to other endmembersearch algorithms by including a constraint on the spatial adjacency of endmembercandidate pixels. Consequently it can reduce the susceptibility to outlier pixels andgenerates realistic endmembers.This is demonstrated using two case studies (AVIRISCuprite cube and Probe-1 imagery for Baffin Island) where image endmembers can bevalidated with ground truth data. The SPA algorithm extracts endmembers fromhyperspectral data without having to reduce the data dimensionality. It uses the spectralangle (alike IEA) and the spatial adjacency of pixels in the image to constrain the selectionof candidate pixels representing an endmember. We designed SPA based on theobservation that many targets have spatial continuity (e.g. bedrock lithologies) in imageryand thus a spatial constraint would be beneficial in the endmember search. An additionalproduct of the SPA is data describing the change of the simplex volume ratio between successive iterations during the endmember extraction. It illustrates the influence of a newendmember on the data structure, and provides information on the convergence of thealgorithm. It can provide a general guideline to constrain the total number of endmembersin a search. Full article

(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)

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Regional geology of south-western Baffin Island and zoom of local geology of the study area (1:100 000) (modified from St-Onge et al., 1999). Full article ">
Probe 1 hyperspectral data of the study area. Circles represent ground locations where field spectra and samples were collected. Full article ">
Comparison between SPA endmember and PPI endmember(“true”endmember). The solid lines denotes PPI endmembers. Full article ">
Comparison of SPA and SMACC endmembers. a) endmember representatives of the same target (zeolite), b) SMACC endmember capturing noise Full article ">
Convergence of SPA for the Cuprite data. The arrow marks the last iteration where the simplex volume ratio for successive iterations exceeds 1.0. Full article ">
Endmember spectra for snow, vegetation and lichen. The dashed lines are the SPA-endmembers, and the solid lines are the corresponding closely matched field spectra. The strong water absorption features near 1.4 and 1.9 um were discarded because of low signal. Full article ">
Comparison of SPA geological endmembers and field spectra. The strong water absorption features near 1.4 and 1.9 um were discarded because of low signal. Full article ">
Comparison between the SPA_11 endmember and field spectrum of peridotite. The circle marks the region where absorption feature is present on the field spectrum of peridotite but absent from the SPA_11. Full article ">
The endmember found by IEA but not by SPA. The solid line is a field spectrum for metasediment, the dashed line is the IEA endmember. Full article ">

6644 KiB

Open AccessArticle

Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting

by Dae Jin Yun, Tae Il Seo and Dong Sam Park

Sensors 2008, 8(2), 1308-1320; https://doi.org/10.3390/s8021308 - 22 Feb 2008

Cited by 22 | Viewed by 11228

Abstract

For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection [...] Read more.

For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection molding and micro hot embossing have been proposed. These techniques, which require a proper photoresist, mask, UV light exposure, developing, and electroplating as a preprocess, are considered to have some problems. In this study, we propose a new microfabrication technology which consists of micro end-milling and powder blasting. This technique could be directly applied to fabricate the metal mold without any preprocesses. The metal mold with micro-channels is machined by micro end-milling, and then, burrs generated in the end-milling process are removed by powder blasting. From the experimental results, micro end-milling combined with powder blasting could be applied effectively for fabrication of the injection mold of biochips with micro fluidic channels. Full article

(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

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388 KiB

Open AccessArticle

Construction of a nrdA::luxCDABE Fusion and Its Use in Escherichia coli as a DNA Damage Biosensor

by Ee Taek Hwang, Joo- Myung Ahn, Byoung Chan Kim and Man Bock Gu

Sensors 2008, 8(2), 1297-1307; https://doi.org/10.3390/s8021297 - 22 Feb 2008

Cited by 18 | Viewed by 11988

Abstract

The promoter of nrdA gene which is related with DNA synthesis was used to construct a DNA damage sensitive biosensor. A recombinant bioluminescent E. coli strain, BBTNrdA, harboring a plasmid with the nrdA promoter fused to the luxCDABE operon, was successfully constructed. Its [...] Read more.

The promoter of nrdA gene which is related with DNA synthesis was used to construct a DNA damage sensitive biosensor. A recombinant bioluminescent E. coli strain, BBTNrdA, harboring a plasmid with the nrdA promoter fused to the luxCDABE operon, was successfully constructed. Its response to various chemicals including genotoxic chemicals substantiates it as a DNA damage biosensor. In characterization, three different classes of toxicants were used: DNA damaging chemicals, oxidative stress chemicals, and phenolics. BBTNrdA only responded strongly to DNA damaging chemicals, such as nalidixic acid (NDA), mitomycin C (MMC), 1-methyl-1-nitroso-N-methylguanidine (MNNG), and 4-nitroquinoline N-oxide (4-NQO). In contrast, there were no responses from the oxidative stress chemicals and phenolics, except from hydrogen peroxide (H2O2) which is known to cause DNA damage indirectly. Therefore, the results of the study demonstrate that BBTNrdA can be used as a DNA damage biosensor. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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1159 KiB

Open AccessArticle

Road Asphalt Pavements Analyzed by Airborne Thermal Remote Sensing: Preliminary Results of the Venice Highway

by Simone Pascucci, Cristiana Bassani, Angelo Palombo, Maurizio Poscolieri and Rosa Cavalli

Sensors 2008, 8(2), 1278-1296; https://doi.org/10.3390/s8021278 - 22 Feb 2008

Cited by 37 | Viewed by 14774

Abstract

This paper describes a fast procedure for evaluating asphalt pavement surface defects using airborne emissivity data. To develop this procedure, we used airborne multispectral emissivity data covering an urban test area close to Venice (Italy).For this study, we first identify and select the [...] Read more.

This paper describes a fast procedure for evaluating asphalt pavement surface defects using airborne emissivity data. To develop this procedure, we used airborne multispectral emissivity data covering an urban test area close to Venice (Italy).For this study, we first identify and select the roads’ asphalt pavements on Multispectral Infrared Visible Imaging Spectrometer (MIVIS) imagery using a segmentation procedure. Next, since in asphalt pavements the surface defects are strictly related to the decrease of oily components that cause an increase of the abundance of surfacing limestone, the diagnostic absorption emissivity peak at 11.2?m of the limestone was used for retrieving from MIVIS emissivity data the areas exhibiting defects on asphalt pavements surface.The results showed that MIVIS emissivity allows establishing a threshold that points out those asphalt road sites on which a check for a maintenance intervention is required. Therefore, this technique can supply local government authorities an efficient, rapid and repeatable road mapping procedure providing the location of the asphalt pavements to be checked. Full article

(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)

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(a) MIVIS scene, outlined in black over a regional map; (b) MIVIS imagery acquired over Venice study area (755 columns × 2956 lines). Full article ">
Flow diagram indicating the steps followed in the methods. Full article ">
Example of an asphalt pavement of the study area with surfacing limestone granules. Full article ">
Examples (a) of new and old emissivity spectra of paving asphalt from the JHU spectral library and (b) of limestone band-depth analysis (intervals 9.59-11.94μm): emissivity continuum-removed absorption peak of a pure limestone spectrum (JHU spectral library), both convolved to MIVIS bandpasses in order to show how its occurrence would affect MIVIS detectability. Full article ">
Object-oriented classification of MIVIS emissivity image. In yellow are depicted the masked highways and exits, they are overlaid on MIVIS channel 13 only for visualization purposes. Full article ">
Estimates of MIVIS SNR in the TIR spectral range calculated on the masked asphalt pavements of the study area. Full article ">
(a) In yellow are depicted the two test areas, selected for training the band-depth analysis; (b) Image showing the band-depth analysis results: in red are depicted the detected asphalt pavements showing surface defects thus to be checked for maintenance. Both images are overlaid on MIVIS channel 13 only for visualization purposes. Full article ">
Images showing an example of asphalt pavements with different surface defects within the study area. Image (b) shows MIVIS emissivity BD classification results. Both images are overlaid on MIVIS channel 13 only for visualization purposes. Full article ">

2044 KiB

Open AccessArticle

Application of GeoWEPP for Determining Sediment Yield and Runoff in the Orcan Creek Watershed in Kahramanmaras, Turkey

by Alaaddin Yüksel, Abdullah E. Akay, Recep Gundogan, Mahmut Reis and Muzaffer Cetiner

Sensors 2008, 8(2), 1222-1236; https://doi.org/10.3390/s8021222 - 22 Feb 2008

Cited by 33 | Viewed by 12606

Abstract

The geo-spatial interface of the WEPP model called GeoWEPP uses digital geo-referenced information integrated with the most common GIS tools to predict sedimentyield and runoff. The model determines where and when the sediment yield and runoffoccurs and locates possible deposition places. In this [...] Read more.

The geo-spatial interface of the WEPP model called GeoWEPP uses digital geo-referenced information integrated with the most common GIS tools to predict sedimentyield and runoff. The model determines where and when the sediment yield and runoffoccurs and locates possible deposition places. In this study, the sediment yield and runofffrom Orcan Creek watershed in Kahramanmaras region was estimated by using GeoWEPPmodel. To investigate the performance of the model, the sediment yield and runoff resultsfrom the GeoWEPP model were compared with the observed monthly data collected fromthe sample watershed. The average Root Mean Square Errors (RMSE) between observedand predicted average annual sediment yield and runoff were 2.96 and 8.43, respectively.The index of agreement was 0.98 and 0.99 for sediment yield and runoff, respectively,which indicated that the model predictions provided good results. Full article

(This article belongs to the Special Issue Spatio-Temporal Modeling of Solar Radiation, Climate and Biogeochemical Cycles)

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4388 KiB

Open AccessReview

Imaging In Mice With Fluorescent Proteins: From Macro To Subcellular

by Robert M. Hoffman

Sensors 2008, 8(2), 1157-1173; https://doi.org/10.3390/s8021157 - 22 Feb 2008

Cited by 19 | Viewed by 15204

Abstract

Whole-body imaging with fluorescent proteins has been shown to be a powerfultechnology with many applications in small animals. Brighter, red-shifted proteins can makewhole-body imaging even more sensitive due to reduced absorption by tissues and less scatter.For example, a new protein called Katushka has [...] Read more.

Whole-body imaging with fluorescent proteins has been shown to be a powerfultechnology with many applications in small animals. Brighter, red-shifted proteins can makewhole-body imaging even more sensitive due to reduced absorption by tissues and less scatter.For example, a new protein called Katushka has been isolated that is the brightest known proteinwith emission at wavelengths longer than 620 nm. This new protein offers potential for non-invasive whole-body macro imaging such as of tumor growth. For subcellular imaging, toobserve cytoplasmic and nuclear dynamics in the living mouse, cancer cells were labeled in thenucleus with green fluorescent protein and with red fluorescent protein in the cytoplasm. Thenuclear and cytoplasmic behavior of cancer cells in real time in blood vessels was imaged as theytrafficked by various means or adhered to the vessel surface in the abdominal skin flap. Duringextravasation, real-time dual-color imaging showed that cytoplasmic processes of the cancer cellsexited the vessels first, with nuclei following along the cytoplasmic projections. Both cytoplasmand nuclei underwent deformation during extravasation. Cancer cells trafficking in lymphaticvessels was also imaged. To noninvasively image cancer cell/stromal cell interaction in the tumormicroenvironment as well as drug response at the cellular level in live animals in real time, wedeveloped a new imageable three-color animal model. The model consists of GFP-expressingmice transplanted with the dual-color cancer cells. With the dual-color cancer cells and a highlysensitive small animal imaging system, subcellular dynamics can now be observed in live mice inreal time. Fluorescent proteins thus enable both macro and micro imaging technology and thereby provide the basis for the new field of in vivo cell biology. Full article

(This article belongs to the Special Issue Bioanalysis in Vivo/in Vitro)

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4057 KiB

Open AccessArticle

Using ASTER Imagery in Land Use/cover Classification of Eastern Mediterranean Landscapes According to CORINE Land Cover Project

by Alaaddin Yüksel, Abdullah E. Akay and Recep Gundogan

Sensors 2008, 8(2), 1237-1251; https://doi.org/10.3390/s8021287 - 21 Feb 2008

Cited by 62 | Viewed by 16609

Abstract

The satellite imagery has been effectively utilized for classifying land covertypes and detecting land cover conditions. The Advanced Spaceborne Thermal Emissionand Reflection Radiometer (ASTER) sensor imagery has been widely used in classificationprocess of land cover. However, atmospheric corrections have to be made by [...] Read more.

The satellite imagery has been effectively utilized for classifying land covertypes and detecting land cover conditions. The Advanced Spaceborne Thermal Emissionand Reflection Radiometer (ASTER) sensor imagery has been widely used in classificationprocess of land cover. However, atmospheric corrections have to be made by preprocessingsatellite sensor imagery since the electromagnetic radiation signals received by the satellitesensors can be scattered and absorbed by the atmospheric gases and aerosols. In this study,an ASTER sensor imagery, which was converted into top-of-atmosphere reflectance(TOA), was used to classify the land use/cover types, according to COoRdination ofINformation on the Environment (CORINE) land cover nomenclature, for an arearepresenting the heterogonous characteristics of eastern Mediterranean regions inKahramanmaras, Turkey. The results indicated that using the surface reflectance data ofASTER sensor imagery can provide accurate (i.e. overall accuracy and kappa values of83.2% and 0.79, respectively) and low-cost cover mapping as a part of inventory forCORINE Land Cover Project. Full article

(This article belongs to the Special Issue Spatio-Temporal Modeling of Solar Radiation, Climate and Biogeochemical Cycles)

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437 KiB

Open AccessArticle

An Auto-Recognizing System for Dice Games Using a Modified Unsupervised Grey Clustering Algorithm

by Kuo-Yi Huang

Sensors 2008, 8(2), 1212-1221; https://doi.org/10.3390/s8021212 - 21 Feb 2008

Cited by 19 | Viewed by 11568

Abstract

In this paper, a novel identification method based on a machine vision system is proposed to recognize the score of dice. The system employs image processing techniques, and the modified unsupervised grey clustering algorithm (MUGCA) to estimate the location of each die and [...] Read more.

In this paper, a novel identification method based on a machine vision system is proposed to recognize the score of dice. The system employs image processing techniques, and the modified unsupervised grey clustering algorithm (MUGCA) to estimate the location of each die and identify the spot number accurately and effectively. The proposed algorithms are substituted for manual recognition. From the experimental results, it is found that this system is excellent due to its good capabilities which include flexibility, high speed, and high accuracy. Full article

(This article belongs to the Special Issue Intelligent Sensors)

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1431 KiB

Open AccessArticle

Dependence of Impedance of Embedded Single Cells on Cellular Behaviour

by Sungbo Cho, Marc Castellarnau, Josep Samitier and Hagen Thielecke

Sensors 2008, 8(2), 1198-1211; https://doi.org/10.3390/s8021198 - 21 Feb 2008

Cited by 11 | Viewed by 14572

Abstract

Non-invasive single cell analyses are increasingly required for the medicaldiagnostics of test substances or the development of drugs and therapies on the single celllevel. For the non-invasive characterisation of cells, impedance spectroscopy whichprovides the frequency dependent electrical properties has been used. Recently,microfludic systems [...] Read more.

Non-invasive single cell analyses are increasingly required for the medicaldiagnostics of test substances or the development of drugs and therapies on the single celllevel. For the non-invasive characterisation of cells, impedance spectroscopy whichprovides the frequency dependent electrical properties has been used. Recently,microfludic systems have been investigated to manipulate the single cells and tocharacterise the electrical properties of embedded cells. In this article, the impedance ofpartially embedded single cells dependent on the cellular behaviour was investigated byusing the microcapillary. An analytical equation was derived to relate the impedance ofembedded cells with respect to the morphological and physiological change ofextracellular interface. The capillary system with impedance measurement showed afeasibility to monitor the impedance change of embedded single cells caused bymorphological and physiological change of cell during the addition of DMSO. By fittingthe derived equation to the measured impedance of cell embedded at different negativepressure levels, it was able to extrapolate the equivalent gap and gap conductivity betweenthe cell and capillary wall representing the cellular behaviour. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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Schematic of a single cell with high surface tension of membrane partially embedded in the tip of capillary with length L, thickness t, and inner radius r, g: interfacial equivalent gap between the cell and capillary, li: length of cylindrically shaped cell body in the capillary, ri: polar radius of semi-eccentrically shaped end of cell in the capillary, ro : radius of spherically shaped cell external to the capillary entrance, <math display="inline"> <semantics id="sm6"> <mrow> <mi>a</mi> <mo>=</mo> <msup> <mrow> <mrow> <mo>{</mo> <mrow> <msubsup> <mi>r</mi> <mi>o</mi> <mn>2</mn></msubsup> <mo>−</mo> <msup> <mi>r</mi> <mn>2</mn></msup></mrow> <mo>}</mo></mrow></mrow> <mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>2</mn></mrow></mrow></msup></mrow></semantics></math>, θ1 = cos−1((r + t)/ro). Full article ">
Schematic of experimental setup for impedance measurement of a single cell at the tip of a capillary. Full article ">
Contribution of resistance in the region 3 of <a href="#f1-sensors-08-01198" class="html-fig">Figure 1</a> to the total resistance difference of an embedded cell (R3/Rdiff) at different length of embedded cell li with equivalent gap g (t = 1 μm, r = 4 μm, ri = 2 μm, ro = 12 μm, σm, σg = 1.6 S/m) (A) or with gap conductivity σg (t = 1 μm, r = 4 μm, ri = 2 μm, ro = 12 μm, g = 40 nm, σm = 1.6 S/m) (B). Full article ">
A: Measured impedance spectra for a L929 cell captured at the tip of capillary and for a capillary without cell, B and C: Change of impedance magnitude (|Z|capture − |Z|non-capture) at 100 Hz in response on the following events: (a) capture, (b) application of DMSO (100 μl of culture medium with 5% DMSO into 1 ml medium in the dish, (c) cell membrane breakdown, and (d) release, In panel B, the impedance for a latex bead captured at the capillary is shown additionally. Full article ">
A: Measured impedance spectra for a L929 cell captured at the tip of capillary and for a capillary without cell, B and C: Change of impedance magnitude (|Z|capture − |Z|non-capture) at 100 Hz in response on the following events: (a) capture, (b) application of DMSO (100 μl of culture medium with 5% DMSO into 1 ml medium in the dish, (c) cell membrane breakdown, and (d) release, In panel B, the impedance for a latex bead captured at the capillary is shown additionally. Full article ">
Micrographs of an embedded cell when the level of negative pressure is 8.3 mbar at 300 s, 11 mbar at 500 s, 15.5 mbar at 700 s, and 21.1 mbar at 900 s (A), the difference of impedance magnitude at 100 Hz during the aspiration (B), arrow: the time of capture. Full article ">
Equivalent gap (g) and the ratio of gap conductivity to medium one (σg/σm) extrapolated by fitting the equation Rdiff to the difference of impedance magnitude at 100 Hz of <a href="#f5-sensors-08-01198" class="html-fig">Figure 5</a>. Full article ">

1333 KiB

Open AccessArticle

Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)

by Wolfgang Wagner, Carsten Pathe, Marcela Doubkova, Daniel Sabel, Annett Bartsch, Stefan Hasenauer, Günter Blöschl, Klaus Scipal, José Martínez-Fernández and Alexander Löw

Sensors 2008, 8(2), 1174-1197; https://doi.org/10.3390/s80201174 - 21 Feb 2008

Cited by 129 | Viewed by 17759

Abstract

The high spatio-temporal variability of soil moisture is the result of atmosphericforcing and redistribution processes related to terrain, soil, and vegetation characteristics.Despite this high variability, many field studies have shown that in the temporal domainsoil moisture measured at specific locations is correlated to [...] Read more.

The high spatio-temporal variability of soil moisture is the result of atmosphericforcing and redistribution processes related to terrain, soil, and vegetation characteristics.Despite this high variability, many field studies have shown that in the temporal domainsoil moisture measured at specific locations is correlated to the mean soil moisture contentover an area. Since the measurements taken by Synthetic Aperture Radar (SAR)instruments are very sensitive to soil moisture it is hypothesized that the temporally stablesoil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT AdvancedSynthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located inthe Duero basin, Spain. It is found that a time-invariant linear relationship is well suited forrelating local scale (pixel) and regional scale (50 km) backscatter. The observed linearmodel coefficients can be estimated by considering the scattering properties of the terrainand vegetation and the soil moisture scaling properties. For both linear model coefficients,the relative error between observed and modelled values is less than 5 % and thecoefficient of determination (R²) is 86 %. The results are of relevance for interpreting anddownscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT)and passive (SMOS, AMSR-E) instruments. Full article

(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))

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14585 KiB

Open AccessArticle

Comparison of Remote Sensing Image Processing Techniques to Identify Tornado Damage Areas from Landsat TM Data

by Soe W. Myint, May Yuan, Randall S. Cerveny and Chandra P. Giri

Sensors 2008, 8(2), 1128-1156; https://doi.org/10.3390/s8021128 - 21 Feb 2008

Cited by 57 | Viewed by 14692

Abstract

Remote sensing techniques have been shown effective for large-scale damagesurveys after a hazardous event in both near real-time or post-event analyses. The paperaims to compare accuracy of common imaging processing techniques to detect tornadodamage tracks from Landsat TM data. We employed the direct [...] Read more.

Remote sensing techniques have been shown effective for large-scale damagesurveys after a hazardous event in both near real-time or post-event analyses. The paperaims to compare accuracy of common imaging processing techniques to detect tornadodamage tracks from Landsat TM data. We employed the direct change detection approachusing two sets of images acquired before and after the tornado event to produce a principalcomponent composite images and a set of image difference bands. Techniques in thecomparison include supervised classification, unsupervised classification, and object-oriented classification approach with a nearest neighbor classifier. Accuracy assessment isbased on Kappa coefficient calculated from error matrices which cross tabulate correctlyidentified cells on the TM image and commission and omission errors in the result. Overall,the Object-oriented Approach exhibits the highest degree of accuracy in tornado damagedetection. PCA and Image Differencing methods show comparable outcomes. Whileselected PCs can improve detection accuracy 5 to 10%, the Object-oriented Approachperforms significantly better with 15-20% higher accuracy than the other two techniques. Full article

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1342 KiB

Open AccessArticle

Integrated Electrochemical Analysis System with Microfluidic and Sensing Functions

by Wataru Satoh, Hiroki Hosono, Hiroomi Yokomaku, Katsuya Morimoto, Sanjay Upadhyay and Hiroaki Suzuki

Sensors 2008, 8(2), 1111-1127; https://doi.org/10.3390/s8021111 - 21 Feb 2008

Cited by 27 | Viewed by 10247

Abstract

An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic [...] Read more.

An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), pH,ammonia, urea, and creatinine were integrated. An air gap structure was used for theammonia, urea, and creatinine sensors to realize a rapid response. To enhance thetransport of ammonia that existed or was produced by the enzymatic reactions, the pHof the solution was elevated by mixing it with a NaOH solution using a valve based onelectrowetting. The sensors for GOT and GPT used a freeze-dried substrate matrix torealize rapid mixing. The sample solution was transported to required sensing sites atdesired times. The integrated sensors showed distinct responses when a sample solutionreached the respective sensing sites. Linear relationships were observed between theoutput signals and the concentration or the logarithm of the concentration of theanalytes. An interferent, L-ascorbic acid, could be eliminated electrochemically in thesample injection port. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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209 KiB

Open AccessReview

QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks

by Feng Xia

Sensors 2008, 8(2), 1099-1110; https://doi.org/10.3390/s8021099 - 21 Feb 2008

Cited by 193 | Viewed by 14844

Abstract

A wireless sensor/actuator network (WSAN) is a group of sensors and actuators that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Actuators react to this information by performing appropriate actions. WSANs thus enable cyber [...] Read more.

A wireless sensor/actuator network (WSAN) is a group of sensors and actuators that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Actuators react to this information by performing appropriate actions. WSANs thus enable cyber systems to monitor and manipulate the behavior of the physical world. WSANs are growing at a tremendous pace, just like the exploding evolution of Internet. Supporting quality of service (QoS) will be of critical importance for pervasive WSANs that serve as the network infrastructure of diverse applications. To spark new research and development interests in this field, this paper examines and discusses the requirements, critical challenges, and open research issues on QoS management in WSANs. A brief overview of recent progress is given. Full article

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870 KiB

Open AccessArticle

Improvement of Aptamer Affinity by Dimerization

by Hijiri Hasegawa, Ken-ichi Taira, Koji Sode and Kazunori Ikebukuro

Sensors 2008, 8(2), 1090-1098; https://doi.org/10.3390/s8021090 - 19 Feb 2008

Cited by 143 | Viewed by 15575

Abstract

To increase the affinities of aptamers for their targets, we designed an aptamerdimer for thrombin and VEGF. This design is based on the avidity of the antibody, whichenables the aptamer to connect easily since it is a single-strand nucleic acid. In this study,we [...] Read more.

To increase the affinities of aptamers for their targets, we designed an aptamerdimer for thrombin and VEGF. This design is based on the avidity of the antibody, whichenables the aptamer to connect easily since it is a single-strand nucleic acid. In this study,we connected a 15-mer thrombin-binding aptamer with a 29-mer thrombin-binding aptamer.Each aptamer recognizes a different part of the thrombin molecule, and the aptamer dimerhas a K_d value which is 1/10 of that of the monomers from which it is composed. Also, thedesigned aptamer dimer has higher inhibitory activity than the reported (15-mer) thrombin-inhibiting aptamer. Additionally, we connected together two identical aptamers againstvascular endothelial growth factor (VEGF₁₆₅), which is a homodimeric protein. As in thecase of the anti-thrombin aptamer, the dimeric anti-VEGF aptamer had a much lower K_d value than that of the monomer. This study demonstrated that the dimerization of aptamerseffectively improves the affinities of those aptamers for their targets. Full article

(This article belongs to the Special Issue Bioanalysis in Vivo/in Vitro)

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5964 KiB

Open AccessArticle

Integrating Remote Sensing Data with Directional Two- Dimensional Wavelet Analysis and Open Geospatial Techniques for Efficient Disaster Monitoring and Management

by Yun-Bin Lin, Yu-Pin Lin, Dong-Po Deng and Kuan-Wei Chen

Sensors 2008, 8(2), 1070-1089; https://doi.org/10.3390/s8021070 - 19 Feb 2008

Cited by 13 | Viewed by 13442

Abstract

In Taiwan, earthquakes have long been recognized as a major cause oflandslides that are wide spread by floods brought by typhoons followed. Distinguishingbetween landslide spatial patterns in different disturbance regimes is fundamental fordisaster monitoring, management, and land-cover restoration. To circumscribe landslides,this study adopts [...] Read more.

In Taiwan, earthquakes have long been recognized as a major cause oflandslides that are wide spread by floods brought by typhoons followed. Distinguishingbetween landslide spatial patterns in different disturbance regimes is fundamental fordisaster monitoring, management, and land-cover restoration. To circumscribe landslides,this study adopts the normalized difference vegetation index (NDVI), which can bedetermined by simply applying mathematical operations of near-infrared and visible-redspectral data immediately after remotely sensed data is acquired. In real-time disastermonitoring, the NDVI is more effective than using land-cover classifications generatedfrom remotely sensed data as land-cover classification tasks are extremely time consuming.Directional two-dimensional (2D) wavelet analysis has an advantage over traditionalspectrum analysis in that it determines localized variations along a specific direction whenidentifying dominant modes of change, and where those modes are located in multi-temporal remotely sensed images. Open geospatial techniques comprise a series ofsolutions developed based on Open Geospatial Consortium specifications that can beapplied to encode data for interoperability and develop an open geospatial service for sharing data. This study presents a novel approach and framework that uses directional 2Dwavelet analysis of real-time NDVI images to effectively identify landslide patterns andshare resulting patterns via open geospatial techniques. As a case study, this study analyzedNDVI images derived from SPOT HRV images before and after the ChiChi earthquake(7.3 on the Richter scale) that hit the Chenyulan basin in Taiwan, as well as images aftertwo large typhoons (Xangsane and Toraji) to delineate the spatial patterns of landslidescaused by major disturbances. Disturbed spatial patterns of landslides that followed theseevents were successfully delineated using 2D wavelet analysis, and results of patternrecognitions of landslides were distributed simultaneously to other agents using geographymarkup language. Real-time information allows successive platforms (agents) to work withlocal geospatial data for disaster management. Furthermore, the proposed is suitable fordetecting landslides in various regions on continental, regional, and local scales usingremotely sensed data in various resolutions derived from SPOT HRV, IKONOS, andQuickBird multispectral images. Full article

(This article belongs to the Special Issue Sensors for Disaster and Emergency Management Decision Making)

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267 KiB

Open AccessArticle

Influence of Cadmium(II) Ions and Brewery Sludge on Metallothionein Level in Earthworms (Eisenia fetida) – Bio- transforming of Toxic Wastes

by Dalibor Huska, Sona Krizkova, Miroslava Beklova, Ladislav Havel, Josef Zehnalek, Vaclav Diopan, Vojtech Adam, Ladislav Zeman, Petr Babula and Rene Kizek

Sensors 2008, 8(2), 1039-1047; https://doi.org/10.3390/s8021039 - 19 Feb 2008

Cited by 18 | Viewed by 9292

Abstract

Metallothioneins belong to a group of intracellular, high molecular andcysteine-rich proteins whose content in an organism increase with increasing concentrationof a heavy metal. The aim of this work was to apply the electrochemical analysis for theanalysis of metallothioneins in earthworms exposed to cadmium [...] Read more.

Metallothioneins belong to a group of intracellular, high molecular andcysteine-rich proteins whose content in an organism increase with increasing concentrationof a heavy metal. The aim of this work was to apply the electrochemical analysis for theanalysis of metallothioneins in earthworms exposed to cadmium ions and brewery sludge.Here we utilized adsorptive transfer technique coupled with differential pulse voltammetryBrdicka reaction to determine metallothionein in different biological samples. By meansthis very sensitive technique it was possible to analyze metallothionein in concentrationsbelow 1 ?mol.l^-1 with the standard deviation of 4-5%. We found out that the average MTlevel in the non-treated earthworms oscillated between 19 and 48 ?mol.l^-1. When weanalysed samples of earthworms treated by cadmium, we observed that the MT contentincreased with the exposition length and increase dose of cadmium ions. Finally, weattempted to study and compare the toxicity of the raw sludge and its leach by using ofearthworms. The raw brewery sludge caused the death of the earthworms quickly.Earthworms held in the presence of leach from brewery sludge increased their weight of147 % of their original weight because they ingested the nutrients from the sludge. Themetallothionein level changes markedly with increasing time of exposition and applieddose of toxic compound. It clearly follows from the obtained results that the MT synthesisis insufficient in the first hours of the exposition and increases after more than 24 h. Full article

(This article belongs to the Special Issue Utilization of Electrochemical Sensors and Biosensors in Biochemistry and Molecular Biology)

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1148 KiB

Open AccessReview

Selective Chemical Labeling of Proteins with Small Fluorescent Molecules Based on Metal-Chelation Methodology

by Nobuaki Soh

Sensors 2008, 8(2), 1004-1024; https://doi.org/10.3390/s8021004 - 19 Feb 2008

Cited by 75 | Viewed by 14171

Abstract

Site-specific chemical labeling utilizing small fluorescent molecules is apowerful and attractive technique for in vivo and in vitro analysis of cellular proteins,which can circumvent some problems in genetic encoding labeling by large fluorescentproteins. In particular, affinity labeling based on metal-chelation, advantageous due to [...] Read more.

Site-specific chemical labeling utilizing small fluorescent molecules is apowerful and attractive technique for in vivo and in vitro analysis of cellular proteins,which can circumvent some problems in genetic encoding labeling by large fluorescentproteins. In particular, affinity labeling based on metal-chelation, advantageous due to thehigh selectivity/simplicity and the small tag-size, is promising, as well as enzymaticcovalent labeling, thereby a variety of novel methods have been studied in recent years.This review describes the advances in chemical labeling of proteins, especially highlightingthe metal-chelation methodology. Full article

(This article belongs to the Special Issue Bioanalysis in Vivo/in Vitro)

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1247 KiB

Open AccessArticle

A Perturbation Method for the 3D Finite Element Modeling of Electrostatically Driven MEMS

by Mohamed Boutaayamou, Ruth V. Sabariego and Patrick Dular

Sensors 2008, 8(2), 994-1003; https://doi.org/10.3390/s8020994 - 19 Feb 2008

Cited by 1 | Viewed by 11201

Abstract

In this paper, a finite element (FE) procedure for modeling electrostatically actu-ated MEMS is presented. It concerns a perturbation method for computing electrostatic fielddistortions due to moving conductors. The computation is split in two steps. First, an un-perturbed problem (in the absence of [...] Read more.

In this paper, a finite element (FE) procedure for modeling electrostatically actu-ated MEMS is presented. It concerns a perturbation method for computing electrostatic fielddistortions due to moving conductors. The computation is split in two steps. First, an un-perturbed problem (in the absence of certain conductors) is solved with the conventional FEmethod in the complete domain. Second, a perturbation problem is solved in a reduced re-gion with an additional conductor using the solution of the unperturbed problem as a source.When the perturbing region is close to the original source field, an iterative computation maybe required. The developed procedure offers the advantage of solving sub-problems in re-duced domains and consequently of benefiting from different problem-adapted meshes. Thisapproach allows for computational efficiency by decreasing the size of the problem. Full article

(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

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A moving micro-beam carrying a floating potential inside a parrallel-plate capacitor Full article ">
Mesh of Ω (1); distribution of the unperturbed electric potential υu (2) and electrice field eu (3); adapted mesh of Ωp (4); distribution of the perturbation electric potential υ (5) and the perturbed one υp (6); distribution of the perturbation electric field e (7) and the perturbed one ep (8) Full article ">
Meshes for the perturbation problems without (left) and with a shell for transformation to infinity (right) Full article ">
ep (y-component) computed along the micro-beam top surface for different perturbing regions (left). Relative error of ep (y-component) with respect to the FE solution in each perturbing region (right) Full article ">
Relative error of υp(left) and ep (y-component) (right) computed along the micro-beam top surface for several distances separating electrode at 1V and the micro-beam Full article ">
Relative error of υp (left) and e p (y-component) (right) computed along the micro-beam top surface for some iterations Full article ">
Iteration numbers to achieve the convergence versus the distance separating electrode at 1V and the micro-beam Full article ">

583 KiB

Open AccessArticle

Laboratory Evaluation of Acoustic Backscatter and LISST Methods for Measurements of Suspended Sediments

by Ramazan Meral

Sensors 2008, 8(2), 979-993; https://doi.org/10.3390/s8020979 - 19 Feb 2008

Cited by 18 | Viewed by 12067

Abstract

The limitation of traditional sampling method to provide detailed spatial andtemporal profiles of suspended sediment concentration has led to an interest in alternativedevices and methods based on scattering of underwater sound and light . In the presentwork, acoustic backscatter and LISST (the Laser [...] Read more.

The limitation of traditional sampling method to provide detailed spatial andtemporal profiles of suspended sediment concentration has led to an interest in alternativedevices and methods based on scattering of underwater sound and light . In the presentwork, acoustic backscatter and LISST (the Laser In Situ Scattering Transmissometry)devices, and methodologies were given. Besides a laboratory study was conducted tocompare pumping methods for different sediment radiuses at the same concentration. Theglass spheres (ballotini) of three different radiuses of 115, 137 and 163 ?m were used toobtain suspension in the sediment tower at laboratory. A quite good agreement wasobtained between these methods and pumping results with the range at 60.6-94.2% forsediment concentration and 91.3-100% for radius measurements. These results and theother studies show that these methods have potential for research tools for sedimentstudies. In addition further studies are needed to determine the ability of these methods forsediment measurement under different water and sediment material conditions. Full article

(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)

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The LISST devices elements: (a) laser diode source, (b) companion focusing optics, (c) and (e) two pressure windows, (d) sample volume, (f) receiving lens, (g) concentric photodetector rings, (h) transmission detector Full article ">
The sediment tower used for ABS measurement (Adopted from Thorne and Hanes, 2002 [<a href="#b1-sensors-08-00979" class="html-bibr">1</a>]). Full article ">
The backscatter voltages from suspension for each frequency and radius. Full article ">
The mean sediment concentration results of ABS measurements for 3 different frequency. Full article ">
Sediment radius results of ABS measurements. Full article ">
The laser transmission results of LISST measurements. Full article ">
The scattering distribution of LISST measurements. Full article ">
Sediment concentration results of LISST measurements. Full article ">
Sediment radius results of LISST measurements Full article ">

373 KiB

Open AccessArticle

Preliminary Results on Design and Implementation of a Solar Radiation Monitoring System

by Mugur C. Balan, Mihai Damian and Lorentz Jäntschi

Sensors 2008, 8(2), 963-978; https://doi.org/10.3390/s8020963 - 19 Feb 2008

Cited by 25 | Viewed by 9400

Abstract

The paper presents a solar radiation monitoring system, using two scientificpyranometers and an on-line computer home-made data acquisition system. The firstpyranometer measures the global solar radiation and the other one, which is shaded,measure the diffuse radiation. The values of total and diffuse solar [...] Read more.

The paper presents a solar radiation monitoring system, using two scientificpyranometers and an on-line computer home-made data acquisition system. The firstpyranometer measures the global solar radiation and the other one, which is shaded,measure the diffuse radiation. The values of total and diffuse solar radiation arecontinuously stored into a database on a server. Original software was created for dataacquisition and interrogation of the created system. The server application acquires the datafrom pyranometers and stores it into a database with a baud rate of one record at 50seconds. The client-server application queries the database and provides descriptivestatistics. A web interface allow to any user to define the including criteria and to obtainthe results. In terms of results, the system is able to provide direct, diffuse and totalradiation intensities as time series. Our client-server application computes also derivateheats. The ability of the system to evaluate the local solar energy potential is highlighted. Full article

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1400 KiB

Open AccessArticle

Effects of van der Waals Force and Thermal Stresses on Pull-in Instability of Clamped Rectangular Microplates

by Romesh C. Batra, Maurizio Porfiri and Davide Spinello

Sensors 2008, 8(2), 1048-1069; https://doi.org/10.3390/s8021048 - 15 Feb 2008

Cited by 101 | Viewed by 12267

Abstract

We study the influence of von Karman nonlinearity, van der Waals force, and a athermal stresses on pull-in instability and small vibrations of electrostatically actuated mi-croplates. We use the Galerkin method to develop a tractable reduced-order model for elec-trostatically actuated clamped rectangular microplates [...] Read more.

We study the influence of von Karman nonlinearity, van der Waals force, and a athermal stresses on pull-in instability and small vibrations of electrostatically actuated mi-croplates. We use the Galerkin method to develop a tractable reduced-order model for elec-trostatically actuated clamped rectangular microplates in the presence of van der Waals forcesand thermal stresses. More specifically, we reduce the governing two-dimensional nonlineartransient boundary-value problem to a single nonlinear ordinary differential equation. For thestatic problem, the pull-in voltage and the pull-in displacement are determined by solving apair of nonlinear algebraic equations. The fundamental vibration frequency corresponding toa deflected configuration of the microplate is determined by solving a linear algebraic equa-tion. The proposed reduced-order model allows for accurately estimating the combined effectsof van der Waals force and thermal stresses on the pull-in voltage and the pull-in deflectionprofile with an extremely limited computational effort. Full article

(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

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601 KiB

Open AccessArticle

LQER: A Link Quality Estimation based Routing for Wireless Sensor Networks

by Jiming Chen, Ruizhong Lin, Yanjun Li and Youxian Sun

Sensors 2008, 8(2), 1025-1038; https://doi.org/10.3390/s8021025 - 15 Feb 2008

Cited by 44 | Viewed by 13040

Abstract

Routing protocols are crucial to self-organize wireless sensor networks (WSNs),which have been widely studied in recent years. For some specific applications, both energyaware and reliable data transmission need to be considered together. Historical link statusshould be captured and taken into account in making [...] Read more.

Routing protocols are crucial to self-organize wireless sensor networks (WSNs),which have been widely studied in recent years. For some specific applications, both energyaware and reliable data transmission need to be considered together. Historical link statusshould be captured and taken into account in making data forwarding decisions to achievethe data reliability and energy efficiency tradeoff. In this paper, a dynamic window concept(m, k) is presented to record the link historical information and a link quality estimation basedrouting protocol (LQER) are proposed, which integrates the approach of minimum hop fieldand (m, k). The performance of LQER is evaluated by extensive simulation experiments to bemore energy-aware, with lower loss rate and better scalability than MHFR [1] and MCR [2].Thus the WSNs with LQER get longer lifetime of networks and better link quality. Full article

(This article belongs to the Special Issue Energy Efficiency and Intelligent Signal Processing for Wireless Sensing)

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5602 KiB

Open AccessArticle

Improving Distributed Runoff Prediction in Urbanized Catchments with Remote Sensing based Estimates of Impervious Surface Cover

by Jaroslaw Chormanski, Tim Van de Voorde, Tim De Roeck, Okke Batelaan and Frank Canters

Sensors 2008, 8(2), 910-932; https://doi.org/10.3390/s8020910 - 15 Feb 2008

Cited by 79 | Viewed by 15643

Abstract

The amount and intensity of runoff on catchment scale are strongly determinedby the presence of impervious land-cover types, which are the predominant cover types inurbanized areas. This paper examines the impact of different methods for estimatingimpervious surface cover on the prediction of peak [...] Read more.

The amount and intensity of runoff on catchment scale are strongly determinedby the presence of impervious land-cover types, which are the predominant cover types inurbanized areas. This paper examines the impact of different methods for estimatingimpervious surface cover on the prediction of peak discharges, as determined by a fullydistributed rainfall-runoff model (WetSpa), for the upper part of the Woluwe Rivercatchment in the southeastern part of Brussels. The study shows that detailed informationon the spatial distribution of impervious surfaces, as obtained from remotely sensed data,produces substantially different estimates of peak discharges than traditional approachesbased on expert judgment of average imperviousness for different types of urban land use.The study also demonstrates that sub-pixel estimation of imperviousness may be a usefulalternative for more expensive high-resolution mapping for rainfall-runoff modelling atcatchment scale. Full article

(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)

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336 KiB

Open AccessArticle

Networked Estimation with an Area-Triggered Transmission Method

by Vinh Hao Nguyen and Young Soo Suh

Sensors 2008, 8(2), 897-909; https://doi.org/10.3390/s8020897 - 15 Feb 2008

Cited by 46 | Viewed by 9537

Abstract

This paper is concerned with the networked estimation problem in which sensordata are transmitted over the network. In the event-driven sampling scheme known aslevel-crossing or send-on-delta, sensor data are transmitted to the estimator node if thedifference between the current sensor value and the [...] Read more.

This paper is concerned with the networked estimation problem in which sensordata are transmitted over the network. In the event-driven sampling scheme known aslevel-crossing or send-on-delta, sensor data are transmitted to the estimator node if thedifference between the current sensor value and the last transmitted one is greater than agiven threshold. The event-driven sampling generally requires less transmission than thetime-driven one. However, the transmission rate of the send-on-delta method becomeslarge when the sensor noise is large since sensor data variation becomes large due to thesensor noise. Motivated by this issue, we propose another event-driven sampling methodcalled area-triggered in which sensor data are sent only when the integral of differencesbetween the current sensor value and the last transmitted one is greater than a giventhreshold. Through theoretical analysis and simulation results, we show that in the certaincases the proposed method not only reduces data transmission rate but also improvesestimation performance in comparison with the conventional event-driven method. Full article

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SOD and SOA sampling schemes Full article ">
Sensor output with noise in discrete time. Full article ">
Effect of R on data transmission rate and distortion for y(t) = 0.1t + v(t). Full article ">
Effect of R on data transmission rate and distortion for y(t) = 5(1 − e−0.1t) + v(t). Full article ">
Structure of the modified Kalman filter. Full article ">
Estimation error as δ = 0.9, α = 0.0881 in case 1 Full article ">
Estimation error as δ = 0.9, α = 0.0303 in case 2. Full article ">

898 KiB

Open AccessArticle

Generalized Split-Window Algorithm for Estimate of Land Surface Temperature from Chinese Geostationary FengYun Meteorological Satellite (FY-2C) Data

by Bohui Tang, Yuyun Bi, Zhao-Liang Li and Jun Xia

Sensors 2008, 8(2), 933-951; https://doi.org/10.3390/s8020933 - 14 Feb 2008

Cited by 177 | Viewed by 18700

Abstract

On the basis of the radiative transfer theory, this paper addressed the estimate ofLand Surface Temperature (LST) from the Chinese first operational geostationarymeteorological satellite-FengYun-2C (FY-2C) data in two thermal infrared channels (IR1,10.3-11.3 ? m and IR2, 11.5-12.5 ? m ), using the Generalized [...] Read more.

On the basis of the radiative transfer theory, this paper addressed the estimate ofLand Surface Temperature (LST) from the Chinese first operational geostationarymeteorological satellite-FengYun-2C (FY-2C) data in two thermal infrared channels (IR1,10.3-11.3 ? m and IR2, 11.5-12.5 ? m ), using the Generalized Split-Window (GSW)algorithm proposed by Wan and Dozier (1996). The coefficients in the GSW algorithmcorresponding to a series of overlapping ranging of the mean emissivity, the atmosphericWater Vapor Content (WVC), and the LST were derived using a statistical regressionmethod from the numerical values simulated with an accurate atmospheric radiativetransfer model MODTRAN 4 over a wide range of atmospheric and surface conditions.The simulation analysis showed that the LST could be estimated by the GSW algorithmwith the Root Mean Square Error (RMSE) less than 1 K for the sub-ranges with theViewing Zenith Angle (VZA) less than 30° or for the sub-rangs with VZA less than 60°and the atmospheric WVC less than 3.5 g/cm² provided that the Land Surface Emissivities(LSEs) are known. In order to determine the range for the optimum coefficients of theGSW algorithm, the LSEs could be derived from the data in MODIS channels 31 and 32 provided by MODIS/Terra LST product MOD11B1, or be estimated either according tothe land surface classification or using the method proposed by Jiang et al. (2006); and theWVC could be obtained from MODIS total precipitable water product MOD05, or beretrieved using Li et al.’ method (2003). The sensitivity and error analyses in term of theuncertainty of the LSE and WVC as well as the instrumental noise were performed. Inaddition, in order to compare the different formulations of the split-window algorithms,several recently proposed split-window algorithms were used to estimate the LST with thesame simulated FY-2C data. The result of the intercomparsion showed that most of thealgorithms give comparable results Full article

(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)

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274 KiB

Open AccessArticle

A Grain Flow Model to Simulate Grain Yield Sensor Response

by Selcuk Arslan

Sensors 2008, 8(2), 952-962; https://doi.org/10.3390/s8020952 - 9 Feb 2008

Cited by 12 | Viewed by 8011

Abstract

The objective of this study was to develop a flow model for grain combinesbased on the laboratory and field response of an impact based grain flow sensor. The grainflow model developed in this study is of first order with constant coefficients. A computercode [...] Read more.

The objective of this study was to develop a flow model for grain combinesbased on the laboratory and field response of an impact based grain flow sensor. The grainflow model developed in this study is of first order with constant coefficients. A computercode was written to solve the model and to simulate the response of a yield sensor whoseresponse had been determined previously for various types of flow rate inputs both in fieldand laboratory experiments. The computer program for the simulation can alsocompensate for the time delay. The simulation results of the theoretical model suited wellto the experimental data and showed that the model effectively shows the input-outputrelationship of grain flow through a grain combine. This model could be used for periodicflow signals acquired from grain yield sensors. It was concluded that the model postulatedin this study could be further developed to determine the grain yield entering the combineusing the outlet flow rate measured by a yield sensor. Full article

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3186 KiB

Open AccessReview

Metallic Nanomaterials for Sensitivity Enhancement of Fluorescence Detection

by Ewa M. Goldys and Fang Xie

Sensors 2008, 8(2), 886-896; https://doi.org/10.3390/s8020886 - 8 Feb 2008

Cited by 32 | Viewed by 9837

Abstract

Utrasensitive detection of trace analytes by fluorescence benefits forfluorescence amplifying substrates. We review here our recent work concerned withunderstanding of enhancement mechanisms and formation of three such substrates: silverfractals, silver coated gold nanoparticles deposited on glass and fluorescence enhancinggold colloids. Full article

(This article belongs to the Special Issue Photoactive Nanomaterials for Sensitive and Selective Determination of Trace Analyzes)

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1527 KiB

Open AccessArticle

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting

by Ho Su Jang, Myeong Woo Cho and Dong Sam Park

Sensors 2008, 8(2), 877-885; https://doi.org/10.3390/s8020877 - 8 Feb 2008

Cited by 11 | Viewed by 11406

Abstract

This study is to develop a micromachining technology for a light guidepanel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a singleinjection process instead of existing screen printing processes. The micro powder blastingtechnique is applied to form micro dot [...] Read more.

This study is to develop a micromachining technology for a light guidepanel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a singleinjection process instead of existing screen printing processes. The micro powder blastingtechnique is applied to form micro dot patterns on the LGP mold surface. The optimalconditions for masking, laminating, exposure, and developing processes to form the microdot patterns are first experimentally investigated. A LGP mold with masked micro patternsis then machined using the micro powder blasting method and the machinability of themicro dot patterns is verified. A prototype LGP is test- injected using the developed LGPmold and a shape analysis of the patterns and performance testing of the injected LGP arecarried out. As an additional approach, matte finishing, a special surface treatment method,is applied to the mold surface to improve the light diffusion characteristics, uniformity andbrightness of the LGP. The results of this study show that the applied powder blastingmethod can be successfully used to manufacture LGPs with micro patterns by just singleinjection using the developed mold and thereby replace existing screen printing methods. Full article

(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

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Sensors, Volume 8, Issue 2 (February 2008) – 46 articles , Pages 594-1350

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