Sensor Array

We tested the detection properties of four MOX sensors toward different ozone mixtures to identify sets of sensing layers and interfering compounds concentrations most suitable for a reliable detection of ozone. The measurement campaign lasted 1 year divided in four sessions. We collected a substantial amount of measurements (more than 500) with diverse interfering gases: ammonia, ethanol, ethylene, carbon monoxide and humidity. Due to the dimension of the data set it could not be analyzed using the conventional methods generally applied for characterizing gas sensors: evaluating the sensor performance by visual inspection of the sensors responses is unfeasible. For this reason we systematically applied the exploratory data analysis methodology. We used some simple but effective statistical techniques to insight the data. This approach allows us to draw sound conclusions about the causes of variation in the data, e.g. time (sensors' long-term stability) or interfering effects of different chemical compounds. All the analysis techniques employed in this work are implemented in a software package developed at our laboratory.

Wireless sensor networks are composed of a large number of sensors densely deployed in inhospitable physical environments. How to disseminate information energy efficiently throughout such a network is still a challenge. Although energy efficiency is a key concern in wireless sensor networks, it often introduces additional delay. In this work, we first propose an Energy*Delay efficient routing scheme called C 2 E 2 S (Cluster and Chain based Energy*Delay Efficient Routing Scheme) for wireless sensor networks. This scheme is a combination of cluster-based and chainbased approaches. Next, we propose (1) an Energy*Delay-aware routing algorithm for sensors within each k-hop cluster, (2) an Energy-efficient chain construction algorithm for clusterheads. We also consider the network lifetime as an important factor as opposed to other approaches. The simulation results show that C 2 E 2 S consumes less energy, balances the energy and delay metrics, as well as extends the network lifetime compared with other approaches 1

Abstract: Vector sensors measure,both the acoustic pressure and the three components,of particle velocity. Because of this, a vector sensor array (VSA) has the advantage of being able to provide substantially higher directivity with a much,smaller aperture than an array of traditional scalar (pressure only) hydrophones. Although several, most of them theoretic, works were published from early nineties, only in the

Oral administration is the most convenient route for drug therapy. The knowledge of the gastrointestinal transit and specific site for drug delivery is a prerequisite for development of dosage forms. The aim of this work was to demonstrate that is possible to monitor the disintegration process of film-coated magnetic tablets by multi-sensor alternate current Biosusceptometry (ACB) in vivo and in vitro. This method is based on the recording of signals produced by the magnetic tablet using a seven sensors array and signal-processing techniques. The disintegration was confirmed by signals analysis in healthy human volunteers' measurements and in vitro experiments. Results showed that ACB is efficient to characterize the disintegration of dosage forms in the stomach, being a research tool for the development of new pharmaceutical dosage forms. q

Systematic errors can occur in every chemical analysis independent of the method used. In general, the risk of systematic errors can be diminished by separation steps prior to the determination procedure. In sensor measurements systematic errors can be noticed only by analysing real samples with a known concentration of the analyte with a great variety of matrices. The sources for such errors are manifold, although excellent reproducibility of the results is shown. The main reason for a systematically blased result in the field of chemo-and biosensors lies in the influence of the sample matrix on the sensor signal, which ought to be produced by the analyte only. Examples of strong matrix interferences on different sensor principles are presented and a classification of the most prominent systematic errors known in analytical chemistry is given. Apart from problems related to a lack of selectivity, which lead to a co-sensing of interferents, the matrix often influences the sensitivity (slope of the calibration curve) and/or the level of the blank signal in an unpredictable manner. Compensation methods, like the well-known blank-signal subtraction or differential sensor measurements, work properly only if certain conditions are fultilled. The principle of signal additivity has to be proven and the invariance of the sensitivity has to be demonstrated in any case and for different matrices. With sensor arrays these requirements must be fulfilled as well.

Austenitic stainless steels (hereafter A-STS) such as STS304 and STS316 are paramagnetic metals. However, a small amount of partial magnetization is generated in A-STS because of the imperfect final heat treatment and mechanical processing. Surface cracks on paramagnetic metal with a partially magnetized region (hereafter PMR) are difficult to inspect. In this paper, we propose a method for high speed inspection and evaluation of a crack on A-STS. Cracks can be inspected with high speed by using 64 arrayed Hall sensors (HSA) with 3.5 mm spatial resolution and a sheet type induced current (STIC). Then, a crack can be evaluated quantitatively by using the detailed distribution of the magnetic field obtained by using single Hall sensor scanning (SSS) around the inspected crack area. Several cracks on A-STS with partially magnetized areas were examined and the experimental formulas were derived.

A low dark current CMOS image sensor (CIS) pixel without any process modification is developed. Dark current is mainly generated at the interface region of shallow trench isolation (STI) structure. Proposed pixel reduces the dark current effectively by separating the STI region from the photodiode junction using simple layout modification. Test sensor array that has both proposed and conventional pixels is fabricated using 0.18 m CMOS process and the characteristics of the sensor are measured. The result shows that the dark current of the proposed pixel is 0.93fA/pixel that is two times lower than the conventional design.

This paper presents a micromagnetoelastic sensor array for simultaneously monitoring multiple biological agents. Magnetoelastic sensors, made of low-cost amorphous ferromagnetic ribbons, are analogous and complementary to piezoelectric acoustic wave sensors, which track parameters of interest via changes in resonance behavior. Magnetoelastic sensors are excited with magnetic ac fields, and, in turn, they generate magnetic fluxes that can be detected with a sensing coil from a distance. As a result, these sensors are highly attractive, not only due to their small size and low cost, but also because of their passive and wireless nature. Magnetoelastic sensors have been applied for monitoring pressure, temperature, liquid density, and viscosity, fluid flow velocity and direction, and with chemical/biological responsive coatings that change mass or elasticity, various biological and chemical agents. In this paper, we report the fabrication and application of a six-sensor array for simultaneous measurement of Escherichia coli O157:H7, staphylococcal enterotoxin B, and ricin. In addition, the sensor array also monitors temperature and pH so the measurements are independent from these two parameters.

Wireless Sensor Networks (WSN) is a research hotspot in recent years and has yielded many fruitful results. However, the biomedical applications of WSN haven’t received significant development due to its many unique challenges for the engineers and physicians. In this paper, a system architecture solution of body area network (BAN), our so called project “MediMesh”, is presented. A biomedical dedicated BAN node hardware platform is devised to fit the medical monitoring application. The sensor node is built up especially for healthcare monitoring while the biocompatibility and portability are considered. A light weight network protocol is designed considering the radiation effect and communication overhead. After data acquisition from sink stations, a data publishing system based on web service technology is implemented for typical hospital environment. The publishing of biomedical data is realized through 3 phases: first storing the data automatically in a database, then creating information sharing service by using Web Service technology, and finally allowing data access by the physicians and end users.

In this paper, the problem of spectral search-free direction-of-arrival (DOA) estimation in arbitrary nonuniform sensor arrays is addressed. In the first part of the paper, we present a finite-sample performance analysis of the well-known manifold separation (MS) based root-MUSIC technique. Then, we propose a new class of search-free DOA estimation methods applicable to arrays of arbitrary geometry and establish their relationship to the MS approach. Our first technique is referred to as Fourier-domain (FD) root-MUSIC and is based on the fact that the spectral MUSIC function is periodic in angle. It uses the Fourier series to expand this function and reformulate the underlying DOA estimation problem as an equivalent polynomial rooting problem. Our second approach applies the zero-padded inverse Fourier transform to the FD root-MUSIC polynomial to avoid the polynomial rooting step and replace it with a simple line search. Our third technique refines the FD root-MUSIC approach by using weighted least-squares approximation to compute the polynomial coefficients. The proposed techniques are shown to offer substantially improved performance-to-complexity tradeoffs as compared to the MS technique.

We examine the improvement attained by using acoustic vector sensors for direction-of-arrival (DOA) estimation, instead of traditional pressure sensors, via optimal performance bounds and particular estimators. By examining the Cramér-Rao bound in the case of a single source, we show that a vectorsensor array's smaller estimation error is a result of two distinct phenomena: 1) an effective increase in signal-to-noise ratio due to a greater number of measurements of phase delays between sensors and 2) direct measurement of the DOA information contained in the structure of the velocity field due to the vector sensors' directional sensitivity. Separate analysis of these two phenomena allows us to determine the array size, array shape, and SNR conditions under which the use of a vector-sensor array is most advantageous and to quantify that advantage. By extending the beamforming and Capon direction estimators to vector sensors, we find that the vector sensors' directional sensitivity removes all bearing ambiguities. In particular, even simple structures such as linear arrays can determine both azimuth and elevation, and spatially undersampled regularly spaced arrays may be employed to increase aperture and, hence, performance. Large sample approximations to the mean-square error matrices of the estimators are derived and their validity is assessed by Monte Carlo simulation.

This paper explores neuro-genetic applications in processing electronic nose data corrupted with additive Gaussian noise. For this study, published sensor data for different polymer-coated surface-acoustic wave (SAW) sensor arrays exposed to fixed concentrations of hazardous vapours like diethyl sulphi de (DES) and iso-octane (ISO) have been used. Dimensionality of resulting pattern recognition problem is varied by taking different numbers of sensors. We show that for low dimensionality instances of this problem, back-propagation performs adequately under noisy conditions. For high dimensionality instances, back-propagation has great difficulty in training the neural classifier even with repeated restarts, and different weights initializations. To alleviate this problem, we propose use of a genetic algorithm with special MRX operator introduced by us and demonstrate very encouraging results with a genetically trained neural network model.

Owing to the growing demand for low-cost 'networkable' sensors in conjunction with recent developments of micro-electro mechanical system (MEMS) and radio frequency (RF) technology, new sensors come with advanced functionalities for processing and communication. Since these nodes are normally very small and powered with irreplaceable batteries, efficient use of energy is paramount and one of the most challenging tasks in designing wireless sensor networks (WSN). A new energy-aware WSN routing protocol, reliable and energy efficient protocol (REEP), which is proposed, makes sensor nodes establish more reliable and energy-efficient paths for data transmission. The performance of REEP has been evaluated under different scenarios, and has been found to be superior to the popular data-centric routing protocol, directed-diffusion (DD) (discussed by Intanagonwiwat et al. in 'Directed diffusion for wireless sensor networking' IEEE/ACM Trans. Netw., 2003, 11(1), pp. 2-16), used as the benchmark.

an important figure of merit in focal pllyle array sensors, especially for accurate target positions such as star trackers. In-situ evaluation by MTF in different stages of imager system developments is necessary for an ideal design of different sensors and their signal processing. Understanding the tradeoff between different figures of merit will enable designers to achieve the most efficient design in specific missions. Advanced active pixel test sensors have been designed and fabricated where different pixel shapes were placed. Research on analyzing the "I?? for the proper pixel shape is currently in progress for a centroidal configuration of a star. Explicit formulas for the modulation transfer function have been studied for the rectangular shaped pixel array. MTF will give us a more complete understanding of the tradeoffs opposed by the different pixel designs and by the signa4 processing conditions. In this paper, preliminary results of two different active pixel sensor ( A P S ) focal plane arrays are presented in terms of crosstalk using a laser. MTF measurements of the A P S arrays are achieved by applying only a single image. A rising or falling edge rather than the conventional bar target of slit scanning is needed to perform the measurement in each direction for the evaluation of the design efficiency.

An improvement has to be made in the inspection speed and the crack detection ability needed to inspect cracks in express train wheels. In this paper a linearly integrated Hall sensor array (LIHaS) is proposed in order to improve the ability for crack detection. In addition, the exclusive parallel signal conditioning circuits, the analog-to-digital convertors, and the interface were developed to reduce the measurement time. The permanent magnet, which applies the vertical magnetic field to the wheel, and the differential-type LIHaS, which measures the distribution of the magnetic field around a crack, is designed to be buried in the rail. An experiment was performed in order to verify the proposed method.

Anomaly detection in a wireless sensor network (WSN) is an important aspect of data analysis in order to identify data items that significantly differ from normal data. A characteristic of the data generated by a WSN is that the data distribution may alter over the lifetime of the network due to the changing nature of the phenomenon being observed. Anomaly detection techniques must be able to adapt to a nonstationary data distribution in order to perform optimally. In this survey, we provide a comprehensive overview of approaches to anomaly detection in a WSN and their operation in a nonstationary environment.

An approach is presented to the problem of detecting the number of sources impinging on a passive sensor array that is based on J. Rissanen's (1983) minimum description length (MDL) principle. The approach is applicable to any type of sources, including the case of sources which are fully correlated, referred to as the coherent signals case. Two slightly different detection criteria are derived, both requiring the estimation of the locations of the sources. The first is tailored to the detection problem per se, whereas the ...

The CAFADIS camera project has consisted in building a camera to measure wave-front phases and distances under different scenarios (from microns to kilometres), using highly specialised electronic technology, namely Graphics Processing Units (GPUs) and Field Programmable Gate Arrays (FPGAs). It is a passive method of depth extraction, it uses incoherent light (natural light). In this paper we will present our new developments.

A dynamic model of a metal-oxide semiconductor gas sensor is proposed and discussed as a tool for obtaining a substantial reduction of the time needed for sensor calibration. The sensor dynamics turn out to be well represented using a simple exponential model. The prediction of the steady-state value from the initial part of the transient permits a reduction of the

Limited battery power at wireless video sensor nodes, along with the transmission quality requirements for video data, makes quality-of-service (QoS) provisioning in a wireless video sensor network a very challenging task. In this paper, a dynamic power-management framework is proposed for a wireless video sensor node to improve the energy-saving performance while satisfying video transmission quality requirements. This framework is developed based on a Markov decision process that considers the video traffic arrival process in the sensor node, the sleep and wakeup processes in the camera and wireless transceiver electronics, the queue status, and the wireless channel condition. A dynamic programming approach is used to find the optimum policy to achieve the desired performance measures in an energylimited sensor node.

The achievement of a proper and uniform pressure distribution between the membrane electrode assembly (MEA) and the bipolar plates of a proton exchange membrane fuel cell (PEMFC) is a key factor of stack design and assembly. Contact pressure levels are usually controlled by selecting an appropriate external clamping pressure on the endplates. Very few studies have been focused on the measurement of the contact pressure distribution within the fuel cell and its correlation with the applied external clamping torque. This study explores the possibility of using matrix-based piezoresistive thin-film sensors, to be placed between the MEA and the monopolar plate of a PEMFC, to investigate this correlation. Before embedding the sensor array into the fuel cell, it was validated for accuracy and repeatability by designing a pneumatic calibration device which allows to apply uniform static pressure levels over the whole sensor area. Preliminary results reported in this study showed that, as the clamping torque on the endplates is increased, the average pressure on the MEA remains almost constant but its distribution changes. The core area of the electrode becomes progressively more unloaded while average stresses on the gasket rise up, with significant stress concentration around the edge corners.

A combined method for the simultaneous measurement of the clamping pressure distribution and endplates deformation in polymer electrolyte fuel cells (PEFC) is presented. The proposed approach, which allows overcoming some important limitations associated with the use of conventional pre-scaled pressure films, is used to investigate the correlation between the actual pressure distribution on the membrane electrode assembly (MEA), the endplate out-of-plane deformation and the applied clamping torque, for two single fuel cells assembled with either copper or aluminium/copper endplates. Results proved that, in point-load design PEFCs, both pressure magnitude and distribution are affected by endplates deformation and thickness mismatching between the sealing gasket and the MEA. Moreover, while the average pressure on the MEA displays a slight increase (+25%) as the clamping torque is raised from 5 to 10 N m, it increases monotonically on the sealing gasket, with local peaks that exceed the saturation level of the sensor array (20.7 MPa). A dimensionless uniformity index has been introduced to assess the uniformity of the pressure distribution, allowing an easy comparison of different fuel cell assembly configurations. The proposed methodology might assist the design of next-generation fuel cells or could be used as a powerful validation tool for detailed finite element models. It can also be applied to study other kind of fuel cells and batteries as well.

Wireless sensor nodes, each a self-powered system performing sensing, communication, and computation, form reliable mesh networks coordinating efforts to add intelligence to the environment. ABSTRACT | Wireless sensor nodes are autonomous devices incorporating sensing, power, computation, and communication into one system. Applications for large scale networks of these nodes are presented in the context of their impact on the hardware design. The demand for low unit cost and multiyear lifetimes, combined with progress in CMOS and MEMS processing, are driving development of SoC solutions for sensor nodes at the cubic centimeter scale with a minimum number of offchip components. Here, the feasibility of a complete, cubic millimeter scale, single-chip sensor node is explored by examining practical limits on process integration and energetic cost of short-range RF communication. Autonomous cubic millimeter nodes appear within reach, but process complexity and substantial sacrifices in performance involved with a true single-chip solution establish a tradeoff between integration and assembly.

Wireless sensor networks have been used to gather data and information in many diverse application settings. The capacity of such networks remains a fundamental obstacle toward the adaptation of sensor network systems for advanced pplications
that require higher data rates and throughput. In this paper, we explore potential benefits of integrating directional antennas into wireless sensor networks. While the usage of directional antennas has been investigated in the past for ad hoc networks, their usage in sensor networks bring both opportunities as well as challenges. In this paper, Sectored-Antenna Medium Access Control (SAMAC), an integrated cross-layer protocol that provides the communication mechanisms for sensor network to fully utilize sectored antennas, is introduced. Simulation studies show that SAMAC delivers high energy efficiency and predictable delay performance with graceful degradation in performance with increased load.

In this paper, we have developed a sleep monitoring and gesture recognition system for patient based on polysomnography which will be useful for patient communication with healthcare personals and/or relatives. In particular, we present the sensor pillow system that employs wireless networks based on low-cost ZigBee technology and a sensor array of force sensitive resistors (FSR) based on polymer thick film (PTF) device for classifying and recognizing sleep posture. This paper also proposes a simple motion model that explains the change of the head pressure distribution. In addition, we can detect some physiological parameters during the sleep stages and wakefulness as well as record cardio-respiratory activity as related to different physiological factors. The integration of the sensor system and wireless technology with a computer software could make this healthcare monitoring system a commercial product valuable for point-of-care applications.

In recent years, there has been a growing interest in wireless sensor networks. One of the major issues in wireless sensor network is developing an energy-efficient clustering protocol. Hierarchical clustering algorithms are very important in increasing the network's life time. Each clustering algorithm is composed of two phases, the setup phase and steady state phase. The hot point in these algorithms is the cluster head selection. In this paper, we study the impact of heterogeneity of nodes in terms of their energy in wireless sensor networks that are hierarchically clustered. We assume that a percentage of the population of sensor nodes is equipped with the additional energy resources. We also assume that the sensor nodes are randomly distributed and are not mobile, the coordinates of the sink and the dimensions of the sensor field are known. Homogeneous clustering protocols assume that all the sensor nodes are equipped with the same amount of energy and as a result, they cannot take the advantage of the presence of node heterogeneity. Adapting this approach, we introduce an energy efficient heterogeneous clustered scheme for wireless sensor networks based on weighted election probabilities of each node to become a cluster head according to the residual energy in each node. Finally, the simulation results demonstrate that our proposed heterogeneous clustering approach is more effective in prolonging the network lifetime compared with LEACH.

The recent interest in the surveillance of public, military, and commercial scenarios is increasing the need to develop and deploy intelligent and/or automated distributed visual surveillance systems. Many applications based on distributed resources use the socalled software agent technology. In this paper, a multi-agent framework is applied to coordinate videocamera-based surveillance. The ability to coordinate agents improves the global image and task distribution efficiency. In our proposal, a software agent is embedded in each camera and controls the capture parameters. Then coordination is based on the exchange of high-level messages among agents. Agents use an internal symbolic model to interpret the current situation from the messages from all other agents to improve global coordination.

The design of a reconfigurable capacitive sensor array interface comprised of a subsystem able to read an array of capacitive-type sensors and an embedded processor is described. Each sensor is connected to a ring oscillator, which translates capacitive changes into a variable-frequency pulse train. An indepth analysis of the oscillator behavior including all parasitic elements has been performed, and the use of a Schmitt trigger at the inverter chain is proposed to assure oscillation for capacitance values ranging from 1 to 1500 pF. The oscillation frequency is estimated by using a 16-b counter and the appropriate userdefined counting interval ranging from a few microseconds to several seconds in order to achieve maximum accuracy within the entire capacitance range. The 2-B word thus produced can be sent to a host computer through a serial or parallel interface for further processing. To demonstrate the concept, a 16-channel interface has been described in a hardware description language and implemented on a complex programmable logic device. Measurement of two different capacitive pressure sensors developed in-house reveals frequency sensitivity values of −252.1 and −9.54 Hz/fF, which are in good agreement with the expected values derived by the analytic relations.

Surface mountable eddy current sensors are a revolutionary new concept in nondestructive inspection. These eddy current sensors can be mounted, like a strain gage, at critical locations for detection of crack initiation and monitoring of crack growth. This can be accomplished on a fatigue test article, as well as on in-service aircraft or other structures (patents pending). The mountable periodic field eddy current sensors, described in this paper, can be used as a replacement for standard eddy-current sensors without introducing new requirements. This is not the case with other proposed health monitoring sensors. For critical structures, substantially reduced inspection costs and life extension is possible with permanently mounted eddy current sensors. This is particularly true for difficult-to-access locations that require surface preparation (e.g., sealant or insulation removal) and disassembly when conventional eddy current testing is performed.

Most multi-camera systems assume a well structured environment to detect and track objects across cameras. Cameras need to be fixed and calibrated, or only objects within a training data can be detected (e.g. pedestrians only). In this work, a master-slave system is presented to detect and track any objects in a network of uncalibrated fixed and mobile cameras. Cameras can have non-overlapping field-of-views. Objects are detected with the mobile cameras (the slaves) given only observations from the fixed cameras (the masters). No training stage and data are used. Detected objects are correctly tracked across cameras leading to a better understanding of the scene.

The development of carbon nanotube-(CNTs-)based gas sensors and sensor arrays has attracted intensive research interest in the last several years because of their potential for the selective and rapid detection of various gaseous species by novel nanostructures integrated in miniature and low-power consuming electronics. Chemiresistors and chemical field effect transistors are probably the most promising types of gas nanosensors. In these sensors, the electrical properties of nanostructures are dramatically changed when exposed to the target gas analytes. In this review, recent progress on the development of different types of CNT-based nanosensors is summarized. The focus was placed on the means used by various researchers to improve the sensing performance (sensitivity, selectivity and response time) through the rational functionalization of CNTs with different methods (covalent and non-covalent) and with different materials (polymers and metals).

We consider the role played by the sensor locations in the optimal performance of an array of acoustic vector sensors. First we derive an expression for the Cramér-Rao bound on the azimuth and elevation of a single far-field source for an arbitrary acoustic vector-sensor array in a homogeneous wholespace and show that it has a block diagonal structure, i.e., the source location parameters are uncoupled from the signal and noise strength parameters. We then derive a set of necessary and sufficient geometrical constraints for the two direction parameters, azimuth and elevation, to be uncoupled from each other. Ensuring that these parameters are uncoupled minimizes the bound and means they are the natural or "canonical" location parameters for the model. We argue that it provides a compelling array design criterion. We also consider a bound on the mean-square angular error and its asymptotic normalization, which are useful measures in three-dimensional bearing estimation problems. We derive an expression for this bound and discuss it in terms of the sensors' locations. We then show that our previously derived geometrical conditions are also sufficient to ensure that this bound is independent of azimuth. Finally, we extend those conditions to obtain a set of geometrical constraints that ensure the optimal performance is isotropic.

Using a circular 37-SQUID (superconducting quantum interference device) sensor array, we observe spontaneous transitions in neuromagneticfield patterns in the human brain which occur at a critical valueof a systematically variedbehavioral parameter. Coherent states of both brain and behavior are captured by the spatiotemporal pattern of phase relations among participating components. Such observations support the thesis that the brain is a pattern forming system that can switch flexibly from one coherent state to another.

Wireless sensor networks (WSNs) offer the potential to significantly improve the efficiency of existing transportation systems. Currently, collecting traffic data for traffic planning and management is achieved mostly through wired sensors. The equipment and maintenance cost and time-consuming installations of existing sensing systems prevent large-scale deployment of real-time traffic monitoring and control. Small wireless sensors with integrated sensing, computing, and wireless communication capabilities offer tremendous advantages in low cost and easy installation. In this paper, we first survey existing WSN technologies for intelligent transportation systems (ITSs), including sensor technologies, energy-efficient networking protocols, and applications of sensor networks for parking lot monitoring, traffic monitoring, and traffic control. Then, we present new methods on applying WSNs in traffic modeling and estimation and traffic control, and show their improved performance over existing solutions. Copyright © 2008 John Wiley & Sons, Ltd.

ROCOM is a four-loop test facility for the investigation of coolant mixing in the primary circuit of pressurized water reactors. Recently, a new sensor was developed for an improved visualisation and quantification of the coolant mixing in the downcomer. This new sensor spans a dense measuring grid and covers nearly the whole downcomer. In the presented work, special emphasis was given to the comparison of the data of this sensor with the results of calculations using the CFD code ANSYS CFX. A coolant mixing experiment during natural circulation conditions has been conducted. The underlying scenario of this experiment is based on a boron dilution scenario following a SBLOCA event. The corresponding CFD code solution has been obtained using the Best Practice Guidelines. All main effects observed in the measurement are described by the calculation. The detailed comparison reveals that the calculation underestimates the coolant mixing inside the reactor pressure vessel.

The technique of interpolated arrays is applied to ESPRIT-type direction finding methods. The resulting method uses sensor arrays with an arbitrary configuration, thus eliminating the basic restrictive requirement of ESPRIT for two (or more) identical arrays. This approach allows for resolving D+1, while the original ESPRIT method requires at least 2D sensors. Moreover, it is shown that while ESPRIT performs poorly for signals propagating in parallel (or close to parallel) with the array displacement vector, the advocated technique does not exhibit such weakness. Finally, using two subarrays, ESPRIT cannot resolve azimuth and elevation even when the sensors are not collinear. However, the interpolated ESPRIT procedure resolves azimuth and elevation using only a single array. The performance of the original ESPRIT when the sensor locations are perturbed is also discussed and illustrated numerically

Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challenges remain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors influencing protocol design. Theoretical network capacity and the state-of-the-art protocols for WMNs are explored with an objective to point out a number of open research issues. Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted.

System aspects of an anti-intruder multistatic radar based on impulse radio ultrawideband (UWB) technology are addressed. The investigated system is composed of one transmitting node and at least three receiving nodes, positioned in the surveillance area with the aim of detecting and locating a human intruder (target) that moves inside the area. Such systems, referred to also as UWB radar sensor networks, must satisfy severe power constraints worldwide imposed by, for example, the Federal Communications Commission (FCC) and by the European Commission (EC) power spectral density masks. A single transmitter-receiver pair (bistatic radar) is considered at first. Given the available transmitted power and the capability of the receiving node to resolve the UWB pulses in the time domain, the surveillance area regions where the target is detectable, and those where it is not, are obtained. Moreover, the range estimation error for the transmitter-receiver pair is discussed. By employing this analysis, a multistatic system is then considered, composed of one transmitter and three or four cooperating receivers. For this multistatic system, the impact of the nodes location on area coverage, necessary transmitted power and localization uncertainty is studied, assuming a circular surveillance area. It is highlighted how area coverage and transmitted power, on one side, and localization uncertainty, on the other side, require opposite criteria of nodes placement. Consequently, the need for a system compromising between these factors is shown. Finally, a simple and effective criterion for placing the transmitter and the receivers is drawn.

A platform for performing rapid, real-time binding assays on sensor arrays based on silicon ring resonators is presented in this paper. An array of 32 sensors is interrogated simultaneously. Using eight sensors as controls, 24 simultaneous binding curves are produced. The bulk refractive index sensitivity of the system was demonstrated down to 7.6 × 10 −7 and sensor-to-sensor variability is 3.9%. Using an 8-min incubation, real-time binding was observed over 8-logs of concentration down to 60 fM using immobilized biotin to capture streptavidin diluted in bovine serum albumin solution. Multiplexing in complex media is demonstrated with two DNA oligonucleotide probes. Time to result and repeatability are demonstrated to be adequate for clinical applications.