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

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Open AccessArticle Optimalization of Poly(neutral red) Coated-wire Electrode for Determination of Citrate in Soft Drinks
Sensors 2008, 8(2), 594-606; doi:10.3390/s8020594
Received: 9 October 2007 / Accepted: 28 January 2008 / Published: 4 February 2008
Cited by 5 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
This report presents an optimization of potentiometric measurements withcitrate-selective electropolymerized poly(neutral red) electrodes. The optimal backgroundelectrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodesdescribed here exhibit stable and reproducible near-Nernstian response to citrates with alow detection limit
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This report presents an optimization of potentiometric measurements withcitrate-selective electropolymerized poly(neutral red) electrodes. The optimal backgroundelectrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodesdescribed here exhibit stable and reproducible near-Nernstian response to citrates with alow detection limit of 6 × 10-6 M. Electrodes polymerized from sulfuric acid andacetonitrile are compared in detail. Simple and sensitive method for quantification ofcitrate in real-life samples by potentiometry with poly(neutral red) electrodes arepresented. Data from potentiometric measurements of citrate are compared with capillaryelectrophoresis. Full article
(This article belongs to the Special Issue Electrochemical Sensors Based on Conductive Polymers)
Open AccessArticle Using Geospatial Information Technology in Natural Resources Management: The Case of Urban Land Management In West Africa
Sensors 2008, 8(2), 607-619; doi:10.3390/s8020607
Received: 4 December 2007 / Accepted: 21 January 2008 / Published: 4 February 2008
Cited by 1 | PDF Full-text (1928 KB) | HTML Full-text | XML Full-text
Abstract
In the past several decades, Lagos Metropolis emerged as one of the fastesturbanizing cities in the West African Sub-region. In the absence of a regular use ofgeospatial information management systems, limited effort had been made to keep track ofchanges in the natural environment
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In the past several decades, Lagos Metropolis emerged as one of the fastesturbanizing cities in the West African Sub-region. In the absence of a regular use ofgeospatial information management systems, limited effort had been made to keep track ofchanges in the natural environment in the rapidly growing city for policy making in landadministration. The ubiquitous energy radiated by the rapid urbanization rate in the areanot only created unprecedented consequences by diminishing the quality of theenvironment and natural resources but it raises serious implications for land managementin the region. The factors fuelling the land crisis in the area which are not far fetchedconsists of socio-economic, ecological and policy elements. To tackle these issues in amega city, up-to-date knowledge would be required to capture and analyze landinformation trends. Such an effort will help manage the city’s expansion as well asinfrastructure development through the right choices in planning and (spatial) designsusing the latest tools in geospatial technologies of Geographic Information Systems GIS)and remote sensing. This study investigates the spatial implications of the rapid expansionof metropolitan Lagos for land management using GIS and Remote sensing technology.The result of the research provides a valuable road map that can enable planners contributeto improved land administration necessary for effective management of natural resources. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Integration of Multiple Data Sources to Simulate the Dynamics of Land Systems
Sensors 2008, 8(2), 620-634; doi:10.3390/s8020620
Received: 25 December 2007 / Accepted: 24 January 2008 / Published: 4 February 2008
Cited by 41 | PDF Full-text (512 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present and develop a new model, which we have calledDynamics of Land Systems (DLS). The DLS model is capable of integrating multiple datasources to simulate the dynamics of a land system. Three main modules are incorporatedin DLS: a spatial
[...] Read more.
In this paper we present and develop a new model, which we have calledDynamics of Land Systems (DLS). The DLS model is capable of integrating multiple datasources to simulate the dynamics of a land system. Three main modules are incorporatedin DLS: a spatial regression module, to explore the relationship between land uses andinfluencing factors, a scenario analysis module of the land uses of a region during thesimulation period and a spatial disaggregation module, to allocate land use changes froma regional level to disaggregated grid cells. A case study on Taips County in North Chinais incorporated in this paper to test the functionality of DLS. The simulation results underthe baseline, economic priority and environmental scenarios help to understand the landsystem dynamics and project near future land-use trajectories of a region, in order tofocus management decisions on land uses and land use planning. Full article
Open AccessArticle Vertex Separators for Partitioning a Graph
Sensors 2008, 8(2), 635-657; doi:10.3390/s8020635
Received: 5 December 2007 / Accepted: 29 January 2008 / Published: 4 February 2008
Cited by 3 | PDF Full-text (496 KB) | HTML Full-text | XML Full-text
Abstract
Finite Element Method (FEM) is a well known technique extensively studiedfor spatial and temporal modeling of environmental processes, weather predictioncomputations, and intelligent signal processing for wireless sensors. The need for hugecomputational power arising in such applications to simulate physical phenomenoncorrectly mandates the use
[...] Read more.
Finite Element Method (FEM) is a well known technique extensively studiedfor spatial and temporal modeling of environmental processes, weather predictioncomputations, and intelligent signal processing for wireless sensors. The need for hugecomputational power arising in such applications to simulate physical phenomenoncorrectly mandates the use of massively parallel computers to distribute the workloadevenly. In this study, a novel heuristic algorithm called Line Graph Bisection whichpartitions a graph via vertex separators so as to balance the workload amongst theprocessors and to minimize the communication overhead is proposed. The proposedalgorithm is proved to be computationally feasible and makes cost-effective parallelimplementations possible to speed up the solution process. Full article
Open AccessArticle Monitoring and Predicting Land-use Changes and the Hydrology of the Urbanized Paochiao Watershed in Taiwan Using Remote Sensing Data, Urban Growth Models and a Hydrological Model
Sensors 2008, 8(2), 658-680; doi:10.3390/s8020658
Received: 10 December 2007 / Accepted: 29 January 2008 / Published: 4 February 2008
Cited by 18 | PDF Full-text (2966 KB) | HTML Full-text | XML Full-text
Abstract
Monitoring and simulating urban sprawl and its effects on land-use patterns andhydrological processes in urbanized watersheds are essential in land-use and waterresourceplanning and management. This study applies a novel framework to the urbangrowth model Slope, Land use, Excluded land, Urban extent, Transportation, andHillshading
[...] Read more.
Monitoring and simulating urban sprawl and its effects on land-use patterns andhydrological processes in urbanized watersheds are essential in land-use and waterresourceplanning and management. This study applies a novel framework to the urbangrowth model Slope, Land use, Excluded land, Urban extent, Transportation, andHillshading (SLEUTH) and land-use change with the Conversion of Land use and itsEffects (CLUE-s) model using historical SPOT images to predict urban sprawl in thePaochiao watershed in Taipei County, Taiwan. The historical and predicted land-use datawas input into Patch Analyst to obtain landscape metrics. This data was also input to theGeneralized Watershed Loading Function (GWLF) model to analyze the effects of futureurban sprawl on the land-use patterns and watershed hydrology. The landscape metrics ofthe historical SPOT images show that land-use patterns changed between 1990–2000. TheSLEUTH model accurately simulated historical land-use patterns and urban sprawl in thePaochiao watershed, and simulated future clustered land-use patterns (2001–2025). TheCLUE-s model also simulated land-use patterns for the same period and yielded historical trends in the metrics of land-use patterns. The land-use patterns predicted by the SLEUTHand CLUE-s models show the significant impact urban sprawl will have on land-usepatterns in the Paochiao watershed. The historical and predicted land-use patterns in thewatershed tended to fragment, had regular shapes and interspersion patterns, but wererelatively less isolated in 2001–2025 and less interspersed from 2005–2025 compared withland-use pattern in 1990. During the study, the variability and magnitude of hydrologicalcomponents based on the historical and predicted land-use patterns were cumulativelyaffected by urban sprawl in the watershed; specifically, surface runoff increasedsignificantly by 22.0% and baseflow decreased by 18.0% during 1990–2025. The proposedapproach is an effective means of enhancing land-use monitoring and management ofurbanized watersheds. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Analysis of Urban-Rural Land-Use Change during 1995-2006 and Its Policy Dimensional Driving Forces in Chongqing, China
Sensors 2008, 8(2), 681-699; doi:10.3390/s8020681
Received: 26 December 2007 / Accepted: 29 January 2008 / Published: 4 February 2008
Cited by 31 | PDF Full-text (2101 KB) | HTML Full-text | XML Full-text
Abstract
This paper analyzes the urban-rural land-use change of Chongqing and its policydimensional driving forces from 1995 to 2006, using high-resolution Landsat TM(Thematic Mapper) data of 1995, 2000 and 2006, and socio-economic data from bothresearch institutes and government departments. The outcomes indicated that urban-ruralland-use
[...] Read more.
This paper analyzes the urban-rural land-use change of Chongqing and its policydimensional driving forces from 1995 to 2006, using high-resolution Landsat TM(Thematic Mapper) data of 1995, 2000 and 2006, and socio-economic data from bothresearch institutes and government departments. The outcomes indicated that urban-ruralland-use change in Chongqing can be characterized by two major trends: First, thenon-agricultural land increased substantially from 1995 to 2006, thus causing agriculturalland especially farmland to decrease continuously. Second, the aggregation index of urbansettlements and rural settlements shows that local urban-rural development experienced aprocess of changing from aggregation (1995-2000) to decentralization (2000-2006).Chongqing is a special area getting immersed in many important policies, which includethe establishment of the municipality directly under the Central Government, the buildingof Three Gorges Dam Project, the Western China Development Program and theGrain-for-Green Programme, and bring about tremendous influences on its land-usechange. By analyzing Chongqing’s land-use change and its policy driving forces, someimplications for its new policy of ‘Urban-rural Integrated Reform’ are obtained. That ismore attentions need to be paid to curbing excessive and idle rural housing andconsolidating rural construction land, and to laying out a scientific land-use plan for its rural areas taking such rural land-use issues as farmland occupation and rural housing landmanagement into accounts, so as to coordinate and balance the urban-rural development. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Micro Fluidic Channel Machining on Fused Silica Glass Using Powder Blasting
Sensors 2008, 8(2), 700-710; doi:10.3390/s8020700
Received: 14 January 2008 / Accepted: 29 January 2008 / Published: 6 February 2008
Cited by 11 | PDF Full-text (4962 KB) | HTML Full-text | XML Full-text
Abstract
In this study, micro fluid channels are machined on fused silica glass via powder blasting, a mechanical etching process, and the machining characteristics of the channels are experimentally evaluated. In the process, material removal is performed by the collision of micro abrasives injected
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In this study, micro fluid channels are machined on fused silica glass via powder blasting, a mechanical etching process, and the machining characteristics of the channels are experimentally evaluated. In the process, material removal is performed by the collision of micro abrasives injected by highly compressed air on to the target surface. This approach can be characterized as an integration of brittle mode machining based on micro crack propagation. Fused silica glass, a high purity synthetic amorphous silicon dioxide, is selected as a workpiece material. It has a very low thermal expansion coefficient and excellent optical qualities and exceptional transmittance over a wide spectral range, especially in the ultraviolet range. The powder blasting process parameters affecting the machined results are injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns. In this study, the influence of the number of nozzle scanning, abrasive particle size, and pattern size on the formation of micro channels is investigated. Machined shapes and surface roughness are measured using a 3-dimensional vision profiler and the results are discussed. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
Open AccessArticle Experimental-Numerical Comparison of the Cantilever MEMS Frequency Shift in presence of a Residual Stress Gradient
Sensors 2008, 8(2), 767-783; doi:10.3390/s8020767
Received: 19 November 2007 / Accepted: 28 January 2008 / Published: 6 February 2008
Cited by 8 | PDF Full-text (638 KB) | HTML Full-text | XML Full-text
Abstract
The dynamic characterization of a set of gold micro beams by electrostatic excitation in presence of residual stress gradient has been studied experimentally. A method to determine the micro-cantilever residual stress gradient by measuring the deflection and curvature and then identifying the residual
[...] Read more.
The dynamic characterization of a set of gold micro beams by electrostatic excitation in presence of residual stress gradient has been studied experimentally. A method to determine the micro-cantilever residual stress gradient by measuring the deflection and curvature and then identifying the residual stress model by means of frequency shift behaviour is presented. A comparison with different numerical FEM models and experimental results has been carried out, introducing in the model the residual stress of the structures, responsible for an initial upward curvature. Dynamic spectrum data are measured via optical interferometry and experimental frequency shift curves are obtained by increasing the dc voltage applied to the specimens. A good correspondence is pointed out between measures and numerical models so that the residual stress effect can be evaluated for different configurations. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
Open AccessArticle Suitability of MEMS Accelerometers for Condition Monitoring: An experimental study
Sensors 2008, 8(2), 784-799; doi:10.3390/s8020784
Received: 30 November 2007 / Accepted: 31 January 2008 / Published: 6 February 2008
Cited by 19 | PDF Full-text (599 KB) | HTML Full-text | XML Full-text
Abstract
With increasing demands for wireless sensing nodes for assets control and condition monitoring; needs for alternatives to expensive conventional accelerometers in vibration measurements have been arisen. Micro-Electro Mechanical Systems (MEMS) accelerometer is one of the available options. The performances of three of the
[...] Read more.
With increasing demands for wireless sensing nodes for assets control and condition monitoring; needs for alternatives to expensive conventional accelerometers in vibration measurements have been arisen. Micro-Electro Mechanical Systems (MEMS) accelerometer is one of the available options. The performances of three of the MEMS accelerometers from different manufacturers are investigated in this paper and compared to a well calibrated commercial accelerometer used as a reference for MEMS sensors performance evaluation. Tests were performed on a real CNC machine in a typical industrial environmental workshop and the achieved results are presented. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
Open AccessArticle An Automatic Instrument to Study the Spatial Scaling Behavior of Emissivity
Sensors 2008, 8(2), 800-816; doi:10.3390/s8020800
Received: 30 December 2007 / Accepted: 30 January 2008 / Published: 8 January 2008
Cited by 2 | PDF Full-text (1898 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the design of an automatic instrument for measuring the spatialdistribution of land surface emissivity is presented, which makes the direct in situmeasurement of the spatial distribution of emissivity possible. The significance of this newinstrument lies in two aspects. One is
[...] Read more.
In this paper, the design of an automatic instrument for measuring the spatialdistribution of land surface emissivity is presented, which makes the direct in situmeasurement of the spatial distribution of emissivity possible. The significance of this newinstrument lies in two aspects. One is that it helps to investigate the spatial scalingbehavior of emissivity and temperature; the other is that, the design of the instrumentprovides theoretical and practical foundations for the implement of measuring distributionof surface emissivity on airborne or spaceborne. To improve the accuracy of themeasurements, the emissivity measurement and its uncertainty are examined in a series ofcarefully designed experiments. The impact of the variation of target temperature and theenvironmental irradiance on the measurement of emissivity is analyzed as well. Inaddition, the ideal temperature difference between hot environment and cool environmentis obtained based on numerical simulations. Finally, the scaling behavior of surfaceemissivity caused by the heterogeneity of target is discussed. Full article
Open AccessArticle Parallel Algorithm for GPU Processing; for use in High Speed Machine Vision Sensing of Cotton Lint Trash
Sensors 2008, 8(2), 817-829; doi:10.3390/s8020817
Received: 30 October 2007 / Accepted: 31 January 2008 / Published: 8 February 2008
Cited by 6 | PDF Full-text (554 KB) | HTML Full-text | XML Full-text
Abstract
One of the main hurdles standing in the way of optimal cleaning of cotton lint isthe lack of sensing systems that can react fast enough to provide the control system withreal-time information as to the level of trash contamination of the cotton lint.
[...] Read more.
One of the main hurdles standing in the way of optimal cleaning of cotton lint isthe lack of sensing systems that can react fast enough to provide the control system withreal-time information as to the level of trash contamination of the cotton lint. This researchexamines the use of programmable graphic processing units (GPU) as an alternative to thePC’s traditional use of the central processing unit (CPU). The use of the GPU, as analternative computation platform, allowed for the machine vision system to gain asignificant improvement in processing time. By improving the processing time, thisresearch seeks to address the lack of availability of rapid trash sensing systems and thusalleviate a situation in which the current systems view the cotton lint either well before, orafter, the cotton is cleaned. This extended lag/lead time that is currently imposed on thecotton trash cleaning control systems, is what is responsible for system operators utilizing avery large dead-band safety buffer in order to ensure that the cotton lint is not undercleaned.Unfortunately, the utilization of a large dead-band buffer results in the majority ofthe cotton lint being over-cleaned which in turn causes lint fiber-damage as well assignificant losses of the valuable lint due to the excessive use of cleaning machinery. Thisresearch estimates that upwards of a 30% reduction in lint loss could be gained through theuse of a tightly coupled trash sensor to the cleaning machinery control systems. Thisresearch seeks to improve processing times through the development of a new algorithm forcotton trash sensing that allows for implementation on a highly parallel architecture.Additionally, by moving the new parallel algorithm onto an alternative computing platform,the graphic processing unit “GPU”, for processing of the cotton trash images, a speed up ofover 6.5 times, over optimized code running on the PC’s central processing unit “CPU”, wasgained. The new parallel algorithm operating on the GPU was able to process a 1024x1024image in less than 17ms. At this improved speed, the image processing system’s performance should now be sufficient to provide a system that would be capable of realtimefeed-back control that is in tight cooperation with the cleaning equipment. Full article
Open AccessArticle An Integrated GIS-Expert System Framework for Live Hazard Monitoring and Detection
Sensors 2008, 8(2), 830-846; doi:10.3390/s8020830
Received: 4 January 2008 / Accepted: 1 February 2007 / Published: 8 February 2008
Cited by 17 | PDF Full-text (614 KB) | HTML Full-text | XML Full-text
Abstract
In the context of hazard monitoring, using sensor web technology to monitor anddetect hazardous conditions in near-real-time can result in large amounts of spatial data thatcan be used to drive analysis at an instrumented site. These data can be used for decisionmaking and
[...] Read more.
In the context of hazard monitoring, using sensor web technology to monitor anddetect hazardous conditions in near-real-time can result in large amounts of spatial data thatcan be used to drive analysis at an instrumented site. These data can be used for decisionmaking and problem solving, however as with any analysis problem the success ofanalyzing hazard potential is governed by many factors such as: the quality of the sensordata used as input; the meaning that can be derived from those data; the reliability of themodel used to describe the problem; the strength of the analysis methods; and the ability toeffectively communicate the end results of the analysis. For decision makers to make use ofsensor web data these issues must be dealt with to some degree. The work described in thispaper addresses all of these areas by showing how raw sensor data can be automaticallytransformed into a representation which matches a predefined model of the problem context.This model can be understood by analysis software that leverages rule-based logic andinference techniques to reason with, and draw conclusions about, spatial data. These toolsare integrated with a well known Geographic Information System (GIS) and existinggeospatial and sensor web infrastructure standards, providing expert users with the toolsneeded to thoroughly explore a problem site and investigate hazards in any domain. Full article
(This article belongs to the Special Issue Sensors for Disaster and Emergency Management Decision Making)
Open AccessArticle Pyridine Vapors Detection by an Optical Fibre Sensor
Sensors 2008, 8(2), 847-859; doi:10.3390/s8020847
Received: 26 December 2007 / Accepted: 4 February 2008 / Published: 8 February 2008
Cited by 17 | PDF Full-text (745 KB) | HTML Full-text | XML Full-text
Abstract
An optical fibre sensor has been implemented towards pyridine vapors detection;to achieve this, a novel vapochromic material has been used, which, in solid state, suffers achange in colour from blue to pink-white in presence of pyridine vapours. This complex isadded to a solution
[...] Read more.
An optical fibre sensor has been implemented towards pyridine vapors detection;to achieve this, a novel vapochromic material has been used, which, in solid state, suffers achange in colour from blue to pink-white in presence of pyridine vapours. This complex isadded to a solution of PVC (Poly Vinyl Chloride), TBP (Tributylphosphate) andtetrahydrofuran (THF), forming a plasticized matrix; by dip coating technique, the sensingmaterial is fixed onto a cleaved ended optical fibre. The fabrication process was optimizedin terms of number of dips and dipping speed, evaluating the final devices by dynamicrange. Employing a reflection set up, the absorbance spectra and changes in the reflectedoptical power of the sensors were registered to determine their response. A linear relationbetween optical power versus vapor concentration was obtained, with a detection limit of 1ppm (v/v). Full article
Open AccessArticle Ocean Color Inferred from Radiometers on Low-Flying Aircraft
Sensors 2008, 8(2), 860-876; doi:10.3390/s8020860
Received: 16 November 2007 / Accepted: 5 February 2008 / Published: 8 February 2008
Cited by 5 | PDF Full-text (1385 KB) | HTML Full-text | XML Full-text
Abstract
The color of sunlight reflected from the ocean to orbiting visible radiometers hasprovided a great deal of information about the global ocean, after suitable corrections aremade for atmospheric effects. Similar ocean-color measurements can be made from a lowflyingaircraft to get higher spatial resolution
[...] Read more.
The color of sunlight reflected from the ocean to orbiting visible radiometers hasprovided a great deal of information about the global ocean, after suitable corrections aremade for atmospheric effects. Similar ocean-color measurements can be made from a lowflyingaircraft to get higher spatial resolution and to obtain measurements under clouds.A different set of corrections is required in this case, and we describe algorithms to correctfor clouds and sea-surface effects. An example is presented and errors in the correctionsdiscussed. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle Micro Dot Patterning on the Light Guide Panel Using Powder Blasting
Sensors 2008, 8(2), 877-885; doi:10.3390/s8020877
Received: 10 January 2008 / Accepted: 6 February 2008 / Published: 8 February 2008
Cited by 9 | PDF Full-text (1527 KB) | HTML Full-text | XML Full-text
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)
Open AccessArticle Networked Estimation with an Area-Triggered Transmission Method
Sensors 2008, 8(2), 897-909; doi:10.3390/s8020897
Received: 18 January 2008 / Accepted: 7 February 2008 / Published: 15 February 2008
Cited by 23 | PDF Full-text (336 KB) | HTML Full-text | XML Full-text
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
Open AccessArticle Improving Distributed Runoff Prediction in Urbanized Catchments with Remote Sensing based Estimates of Impervious Surface Cover
Sensors 2008, 8(2), 910-932; doi:10.3390/s8020910
Received: 15 January 2008 / Accepted: 7 February 2008 / Published: 15 February 2008
Cited by 39 | PDF Full-text (5602 KB) | HTML Full-text | XML Full-text
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)
Open AccessArticle Generalized Split-Window Algorithm for Estimate of Land Surface Temperature from Chinese Geostationary FengYun Meteorological Satellite (FY-2C) Data
Sensors 2008, 8(2), 933-951; doi:10.3390/s8020933
Received: 3 January 2008 / Accepted: 31 January 2008 / Published: 14 February 2008
Cited by 48 | PDF Full-text (898 KB) | HTML Full-text | XML Full-text
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 μ m and IR2, 11.5-12.5 μ 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 μ m and IR2, 11.5-12.5 μ 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)
Open AccessArticle A Grain Flow Model to Simulate Grain Yield Sensor Response
Sensors 2008, 8(2), 952-962; doi:10.3390/s8020952
Received: 18 January 2008 / Accepted: 1 February 2008 / Published: 9 February 2008
Cited by 2 | PDF Full-text (274 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Preliminary Results on Design and Implementation of a Solar Radiation Monitoring System
Sensors 2008, 8(2), 963-978; doi:10.3390/s8020963
Received: 29 December 2007 / Accepted: 4 February 2008 / Published: 19 February 2008
Cited by 8 | PDF Full-text (373 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Laboratory Evaluation of Acoustic Backscatter and LISST Methods for Measurements of Suspended Sediments
Sensors 2008, 8(2), 979-993; doi:10.3390/s8020979
Received: 30 December 2007 / Accepted: 7 February 2008 / Published: 19 February 2008
Cited by 6 | PDF Full-text (583 KB) | HTML Full-text | XML Full-text
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
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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 μm 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)
Open AccessArticle A Perturbation Method for the 3D Finite Element Modeling of Electrostatically Driven MEMS
Sensors 2008, 8(2), 994-1003; doi:10.3390/s8020994
Received: 14 September 2007 / Accepted: 8 February 2008 / Published: 19 February 2008
PDF Full-text (1247 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle LQER: A Link Quality Estimation based Routing for Wireless Sensor Networks
Sensors 2008, 8(2), 1025-1038; doi:10.3390/s8021025
Received: 11 January 2008 / Accepted: 11 February 2008 / Published: 15 February 2008
Cited by 26 | PDF Full-text (601 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Influence of Cadmium(II) Ions and Brewery Sludge on Metallothionein Level in Earthworms (Eisenia fetida) – Bio- transforming of Toxic Wastes
Sensors 2008, 8(2), 1039-1047; doi:10.3390/s8021039
Received: 31 January 2008 / Accepted: 14 February 2008 / Published: 19 February 2008
Cited by 16 | PDF Full-text (267 KB) | HTML Full-text | XML Full-text
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
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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 μmol.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 μmol.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
Open AccessArticle Effects of van der Waals Force and Thermal Stresses on Pull-in Instability of Clamped Rectangular Microplates
Sensors 2008, 8(2), 1048-1069; doi:10.3390/s8021048
Received: 21 December 2007 / Accepted: 14 February 2008 / Published: 15 February 2008
Cited by 50 | PDF Full-text (1400 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Integrating Remote Sensing Data with Directional Two- Dimensional Wavelet Analysis and Open Geospatial Techniques for Efficient Disaster Monitoring and Management
Sensors 2008, 8(2), 1070-1089; doi:10.3390/s8021070
Received: 19 November 2007 / Accepted: 15 February 2008 / Published: 19 February 2008
Cited by 10 | PDF Full-text (5964 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Improvement of Aptamer Affinity by Dimerization
Sensors 2008, 8(2), 1090-1098; doi:10.3390/s8021090
Received: 29 January 2008 / Accepted: 15 February 2008 / Published: 19 February 2008
Cited by 59 | PDF Full-text (870 KB) | HTML Full-text | XML Full-text
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
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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 Kd 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 Kd 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)
Open AccessArticle Integrated Electrochemical Analysis System with Microfluidic and Sensing Functions
Sensors 2008, 8(2), 1111-1127; doi:10.3390/s8021111
Received: 17 January 2008 / Accepted: 18 February 2008 / Published: 21 February 2008
Cited by 12 | PDF Full-text (1342 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Comparison of Remote Sensing Image Processing Techniques to Identify Tornado Damage Areas from Landsat TM Data
Sensors 2008, 8(2), 1128-1156; doi:10.3390/s8021128
Received: 31 December 2007 / Accepted: 19 February 2008 / Published: 21 February 2008
Cited by 21 | PDF Full-text (14585 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)
Sensors 2008, 8(2), 1174-1197; doi:10.3390/s80201174
Received: 11 January 2008 / Accepted: 19 February 2008 / Published: 21 February 2008
Cited by 14 | PDF Full-text (1333 KB) | HTML Full-text | XML Full-text
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
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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))
Open AccessArticle Dependence of Impedance of Embedded Single Cells on Cellular Behaviour
Sensors 2008, 8(2), 1198-1211; doi:10.3390/s8021198
Received: 31 January 2008 / Accepted: 20 February 2007 / Published: 21 February 2008
Cited by 9 | PDF Full-text (1431 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle An Auto-Recognizing System for Dice Games Using a Modified Unsupervised Grey Clustering Algorithm
Sensors 2008, 8(2), 1212-1221; doi:10.3390/s8021212
Received: 17 November 2007 / Accepted: 14 February 2007 / Published: 21 February 2008
Cited by 9 | PDF Full-text (437 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Application of GeoWEPP for Determining Sediment Yield and Runoff in the Orcan Creek Watershed in Kahramanmaras, Turkey
Sensors 2008, 8(2), 1222-1236; doi:10.3390/s8021222
Received: 25 January 2008 / Accepted: 13 February 2008 / Published: 22 February 2008
Cited by 12 | PDF Full-text (2044 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Using ASTER Imagery in Land Use/cover Classification of Eastern Mediterranean Landscapes According to CORINE Land Cover Project
Sensors 2008, 8(2), 1237-1251; doi:10.3390/s8021287
Received: 7 February 2008 / Accepted: 19 February 2008 / Published: 21 February 2008
Cited by 24 | PDF Full-text (4057 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Techno-Economic Analysis of Solar Water Heating Systems inTurkey
Sensors 2008, 8(2), 1252-1277; doi:10.3390/s8021252
Received: 24 January 2008 / Accepted: 19 February 2008 / Published: 25 February 2008
Cited by 5 | PDF Full-text (1941 KB) | HTML Full-text | XML Full-text
Abstract
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
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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
Open AccessArticle Road Asphalt Pavements Analyzed by Airborne Thermal Remote Sensing: Preliminary Results of the Venice Highway
Sensors 2008, 8(2), 1278-1296; doi:10.3390/s8021278
Received: 5 February 2008 / Accepted: 21 February 2008 / Published: 22 February 2008
Cited by 13 | PDF Full-text (1159 KB) | HTML Full-text | XML Full-text
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
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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 11.2μm 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)
Open AccessArticle Construction of a nrdA::luxCDABE Fusion and Its Use in Escherichia coli as a DNA Damage Biosensor
Sensors 2008, 8(2), 1297-1307; doi:10.3390/s8021297
Received: 31 January 2008 / Accepted: 21 February 2008 / Published: 22 February 2008
Cited by 13 | PDF Full-text (388 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting
Sensors 2008, 8(2), 1308-1320; doi:10.3390/s8021308
Received: 15 February 2008 / Accepted: 21 February 2008 / Published: 22 February 2008
Cited by 12 | PDF Full-text (6644 KB) | HTML Full-text | XML Full-text
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)
Open AccessArticle The Successive Projection Algorithm (SPA), an Algorithm with a Spatial Constraint for the Automatic Search of Endmembers in Hyperspectral Data
Sensors 2008, 8(2), 1321-1342; doi:10.3390/s8021321
Received: 28 December 2007 / Accepted: 19 February 2008 / Published: 22 February 2008
Cited by 25 | PDF Full-text (2793 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Range and Velocity Estimation of Moving Targets Using Multiple Stepped-frequency Pulse Trains
Sensors 2008, 8(2), 1343-1350; doi:10.3390/s8021343
Received: 2 February 2008 / Accepted: 20 February 2008 / Published: 22 February 2008
Cited by 14 | PDF Full-text (224 KB) | HTML Full-text | XML Full-text
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
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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)

Review

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Open AccessReview Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review
Sensors 2008, 8(2), 711-738; doi:10.3390/s8020711
Received: 5 November 2007 / Accepted: 29 January 2008 / Published: 6 January 2008
Cited by 61 | PDF Full-text (1124 KB) | HTML Full-text | XML Full-text
Abstract
Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as
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Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as grating couplers and interferometric sensors aswell as fluorescence-based systems benefit from this waveguide material leading toextremely high sensitivity. Some biosensor systems based on Ta2O5 waveguides alreadytook the step into commercialization. This report reviews the various detection systems interms of limit of detection, the applications, and the suitable surface chemistry. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessReview Electroanalysis of NADH Using Conducting and Redox Active Polymer/Carbon Nanotubes Modified Electrodes-A Review
Sensors 2008, 8(2), 739-766; doi:10.3390/s8020739
Received: 31 December 2007 / Accepted: 30 January 2008 / Published: 6 January 2008
Cited by 81 | PDF Full-text (500 KB) | HTML Full-text | XML Full-text
Abstract
Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the
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Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the potential uses of electrogenerated polymer modified electrodes and polymer/carbon nanotubes composite modified electrodes for electroanalysis of reduced form of nicotinamide adenine dinuceltoide (NADH). In addition, carbon electrodes modified with organic and inorganic materials as modifier have been discussed in detail for the quantification of NADH based on mediator or mediator-less methods. Full article
Open AccessReview Metallic Nanomaterials for Sensitivity Enhancement of Fluorescence Detection
Sensors 2008, 8(2), 886-896; doi:10.3390/s8020886
Received: 15 January 2008 / Accepted: 30 January 2008 / Published: 8 February 2008
Cited by 15 | PDF Full-text (3186 KB) | HTML Full-text | XML Full-text
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
Open AccessReview Selective Chemical Labeling of Proteins with Small Fluorescent Molecules Based on Metal-Chelation Methodology
Sensors 2008, 8(2), 1004-1024; doi:10.3390/s8021004
Received: 28 January 2008 / Accepted: 13 February 2008 / Published: 19 February 2008
Cited by 54 | PDF Full-text (1148 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessReview QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks
Sensors 2008, 8(2), 1099-1110; doi:10.3390/s8021099
Received: 29 December 2007 / Accepted: 18 February 2008 / Published: 21 February 2008
Cited by 81 | PDF Full-text (209 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessReview Imaging In Mice With Fluorescent Proteins: From Macro To Subcellular
Sensors 2008, 8(2), 1157-1173; doi:10.3390/s8021157
Received: 15 January 2008 / Accepted: 19 February 2008 / Published: 22 February 2008
Cited by 10 | PDF Full-text (4388 KB) | HTML Full-text | XML Full-text
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
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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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