Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough corr...Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough correlations before we calculate the correlation cost, so it avoids the operations for the target state estimate and the calculation of the correlation cost for the false correlation sets. In the meantime, with the elimination of these points in the rough correlation, the disturbance from the false correlations in the assignment process is decreased, so the data correlation accuracy is improved correspondingly. Complexity analyses of the new multi-layer optimal algorithm and the traditional optimal assignment algorithm are given. Simulation results show that the new algorithm is feasible and effective.展开更多
We investigate the problem of how to minimize the energy consumption in multi-hop Wireless Sensor Network (WSN),under the constraint of end-to-end reliability Quality of Seervice (QoS) requirement.Based on the investi...We investigate the problem of how to minimize the energy consumption in multi-hop Wireless Sensor Network (WSN),under the constraint of end-to-end reliability Quality of Seervice (QoS) requirement.Based on the investigation,we jointly consider the routing,relay selection and power allocation algorithm,and present a novel distributed cross-layer strategy using opportunistic relaying scheme for cooperative communication.The results show that under the same QoS requirement,the proposed cross-layer strategy performs better than other cross-layer cooperative communication algorithms in energy efficiency.We also investigated the impact of several parameters on the energy efficiency of the cooperative communication in WSNs,thus can be used to provide guidelines to decide when and how to apply cooperation for a given setup.展开更多
System integrity is important for fast and accurate measurement and control.LabVIEW is widely used in education and industry.Many LabVIEW codes are hard to be read and shown because of their 2D topology.In order to si...System integrity is important for fast and accurate measurement and control.LabVIEW is widely used in education and industry.Many LabVIEW codes are hard to be read and shown because of their 2D topology.In order to simplify the programming,a 4-layer model of developing sensor or measurement systems with LabVIEW is proposed in this paper.The purpose of this paper is to show the readers how to design simple,clear and strong automated systems with LabVIEW.Using a Sensirion SHT75 humidity sensor and an NI USB6008 DAQ board as an example,this paper describes the steps of developing a sensor system from the physical layer to application layer in detail.In layer 2,port selection and signal regulation are demonstrated.In layer 3,timing waveform analysis and synthesis,state diagram analysis,instruction set design,micro operation and fault tolerance designs are demonstrated.In layer 4,data visualization is covered with a vivid example.Programmers found it was hard to show readers their LabVIEW codes because many LabVIEW codes occupy several screens.A layer model simplifies the programming,so one is able to show a medium size LabVIEW code easily.展开更多
This paper presents a wireless sensor network (WSN) access control algorithm designed to minimize WSN node energy consumption. Based on slotted ALOHA protocol, this algorithm incorporates the power control of physical...This paper presents a wireless sensor network (WSN) access control algorithm designed to minimize WSN node energy consumption. Based on slotted ALOHA protocol, this algorithm incorporates the power control of physical layer, the transmitting probability of medium access control (MAC) layer, and the automatic repeat request (ARQ) of link layer. In this algorithm, a cross-layer optimization is preformed to minimizing the energy consuming per bit. Through theory deducing, the transmitting probability and transmitting power level is determined, and the relationship between energy consuming per bit and throughput per node is provided. Analytical results show that the cross-layer algorithm results in a significant energy savings relative to layered design subject to the same throughput per node, and the energy saving is extraordinary in the low throughput region.展开更多
Lossy link is one of the unique characteristics in random-deployed sensor networks. We envision that robustness and reliability of routing cannot be ensured purely in network layer. Our idea is to enhance the performa...Lossy link is one of the unique characteristics in random-deployed sensor networks. We envision that robustness and reliability of routing cannot be ensured purely in network layer. Our idea is to enhance the performance of routing protocol by cross-layer interaction. We modified mint protocol, a routing protocol in TinyOS and proposed an enhanced version of mint called PA-mint. A transmission power control interface is added to network layer in PA-mint. When routing performance of the current network is not satisfied, PA-mint monotonically increases the transmission power via the interface we added. PA-mint is able to connect orphan nodes and robust to node mobility or key nodes failure. In the case that automatic request retransmission is employed, the number of retransmissions can be reduced by PA-mint. Results from experiments show that PA-mint increases the reliability and robustness of routing protocol by cross-layer interaction.展开更多
A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed...A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit （FOM） depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 （or AlAs） absentee layer is 1.059% （or 2.587%） higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.展开更多
Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions su...Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.展开更多
Abstract--Poly4-vinylphenol （P4VP）/multi-wan carbon nanotubes （MWNTs） multi-layer sensitive films were deposited on interdigitated electrodes by airbrush technology to detect toluene vapor at room temperature. The...Abstract--Poly4-vinylphenol （P4VP）/multi-wan carbon nanotubes （MWNTs） multi-layer sensitive films were deposited on interdigitated electrodes by airbrush technology to detect toluene vapor at room temperature. The surface and section morphologies of the multi-layer films were observed by a scanning electron microscope （SEM）. It is found that the resistance of the sensor increases when it is exposed to toluene vapor and the response has a good linearity with the concentration of toluene. The results show that the P4VP/MWNTs three-layer film sensors have better sensing properties compared with the two-layer film sensors. The related sensing mechanism is studied in detail.展开更多
The main research objective in wireless sensor networks (WSN) domain is to develop algorithms and protocols to ensure minimal energy consumption with maximum network lifetime. In this paper, we propose a novel design ...The main research objective in wireless sensor networks (WSN) domain is to develop algorithms and protocols to ensure minimal energy consumption with maximum network lifetime. In this paper, we propose a novel design for energy harvesting sensor node and cross-layered MAC protocol using three adjacent layers (Physical, MAC and Network) to economize energy for WSN. The basic idea behind our protocol is to re-energize the neighboring nodes using the radio frequency (RF) energy transmitted by the active nodes. This can be achieved by designing new energy harvesting sensor node and redesigning the MAC protocol. The results show that the proposed cross layer CL_EHSN improves the life time of the WSN by 40%.展开更多
In this work, we have developed an electrochemical sensor for nitrite detection, based on a polyoxometalate (POM) namely mono-lacunary keggin anion [SiW11O39]8﹣ cited as (SiW11). Electrochemical characterization of S...In this work, we have developed an electrochemical sensor for nitrite detection, based on a polyoxometalate (POM) namely mono-lacunary keggin anion [SiW11O39]8﹣ cited as (SiW11). Electrochemical characterization of SiW11 shows two-step reduction processes, with formal potentials of ﹣0.5 V (I) and ﹣0.68 V (II). Oppositely charged polyelectrolyte (poly (allylamine hydrochloride) (PAH)) and (SiW11) were assembled alternately to modify glassy carbon electrode. The electrochemical behavior of the modified electrode was studied in detail using cyclic voltammetry (CV). The results showed that SiW11/PAH/GC electrode present good electrocatalytic activity for the reduction of nitrite. The sensor showed a dynamic range from 100 μM to 3.6 mMof nitrite and no interference from other classical anions. Experimental factors that affect electron-transfer rate in these films, such as pH effect and layers number, were systematically analyzed.展开更多
Several protocols and schemes have been proposed to reduce energy consumption in Wireless Sensor Net-works (WSNs). In this paper we employ farcoopt, a cross layer design approach with the concept of coop-eration among...Several protocols and schemes have been proposed to reduce energy consumption in Wireless Sensor Net-works (WSNs). In this paper we employ farcoopt, a cross layer design approach with the concept of coop-eration among the nodes with best farthest neighbor scheme to increase the Quality of Service (QoS), reduce energy consumption, increases performance and end-to-end throughput. We present cooperative transmission to connect previously disconnect parts of a network thus overcoming the separation problem of multi-hop network. We show that this approach improves connectivity over 50% compared to multi-hop approaches and reduces the number of nodes necessary to provide full coverage of an area up to 35%. Simulation results show that on increase of data rates i.e. packet the network life time increases in farcoopt as compared to tra-ditional multi hop approach. The result of this analysis is presented in this work.展开更多
The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the...The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments. A kind of simple structure, small size, good stability, high sensitivity chemical concentration sensor is obtained.展开更多
Researches related to wireless sensor networks primarily concentrate on Routing, Location Services, Data Aggregation and Energy Calculation Methods. Due to the heterogeneity of sensor networks using the web architectu...Researches related to wireless sensor networks primarily concentrate on Routing, Location Services, Data Aggregation and Energy Calculation Methods. Due to the heterogeneity of sensor networks using the web architecture, cross layer mechanism can be implemented for integrating multiple resources. Framework for Sensor Web using the cross layer scheduling mechanisms in the grid environment is proposed in this paper. The resource discovery and the energy efficient data aggregation schemes are used to improvise the effective utilization capability in the Sensor Web. To collaborate with multiple resources environment, the grid computing concept is integrated with sensor web. Resource discovery and the scheduling schemes in the grid architecture are organized using the medium access control protocol. The various cross layer metrics proposed are Memory Awareness, Task Awareness and Energy Awareness. Based on these metrics, the parameters-Node Waiting Status, Used CPU Status, Average System Utilization, Average Utilization per Cluster, Cluster Usage per Hour and Node Energy Status are determined for the integrated heterogeneous WSN with sensor web in Grid Environment. From the comparative analysis, it is shown that sensor grid architecture with middleware framework has better resource awareness than the normal sensor network architectures.展开更多
We consider the extension of network lifetime of battery driven wireless sensor networks by splitting the sensing area into uniform clusters and implementing heterogeneous modulation schemes at different members of th...We consider the extension of network lifetime of battery driven wireless sensor networks by splitting the sensing area into uniform clusters and implementing heterogeneous modulation schemes at different members of the clusters. A cross-layer optimization has been proposed to reduce total energy expenditure of the network;at network layer, routing is done through uniform clusters;at MAC layer, each sensor node of the cluster is assigned fixed or variable time slots and at physical layer different member of the clusters is assigned different modulation techniques. MATLAB simulation proved substantial network lifetime gains.展开更多
Rapid penetration of small customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. Offering precise qual...Rapid penetration of small customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. Offering precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However offering some better QoS for wireless multimedia over sensor networks raises significant challenges. In this paper, we propose an adaptive Cross-Layer multi-channel QoS-MAC protocol to support energy-efficient, high throughput, and reliable data transmission in Wireless Multimedia Sensor Network (WMSNs). Our proposed protocol use benefit of TDMA and CSMA/CA to adaptively assign channels and timeslots to active multimedia sensor nodes in clusters. Simulations show that the proposed system achieves the performance objectives of WMSNs with increased network throughput at the cost of a small control and energy overhead.展开更多
Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coate...Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.展开更多
A coating scheme was developed for enabling the operation of a GaAs-based Molecular Controlled Semiconductor Resistor (MOCSER) under biological conditions. Usually GaAs is susceptible to etching in an aqueous environm...A coating scheme was developed for enabling the operation of a GaAs-based Molecular Controlled Semiconductor Resistor (MOCSER) under biological conditions. Usually GaAs is susceptible to etching in an aqueous environment. Several methods of protecting the semiconductor based devices were suggested previously. However, even when protected, it is very difficult to ensure the operation of a GaAs-based electronic sensor in aqua solution for long periods. We developed a new depositing scheme of (3-mercaptopropyl)-trimethoxysilane (MPTMS) on GaAs substrate consisting of two separate steps. The first involves chemisorption of a dense primary MPTMS layer on the substrate, whereas in the second, a thin MPTMS polymer layer is deposited on the already adsorbed layer, resulting in a 15 -?29 nm thick coating. We show that applying the new MPTMS deposition procedure to GaAs-based MOCSER devices allows up to 15 hours of continuous electrical measurements and stable performance of the sensing device in harsh biological environment. The new protection allows implementing GaAs technology in bioelectronics, particularly in biosensing.展开更多
基金This project was supported by the National Natural Science Foundation of China (60672139, 60672140)the Excellent Ph.D. Paper Author Foundation of China (200237)the Natural Science Foundation of Shandong (2005ZX01).
文摘Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough correlations before we calculate the correlation cost, so it avoids the operations for the target state estimate and the calculation of the correlation cost for the false correlation sets. In the meantime, with the elimination of these points in the rough correlation, the disturbance from the false correlations in the assignment process is decreased, so the data correlation accuracy is improved correspondingly. Complexity analyses of the new multi-layer optimal algorithm and the traditional optimal assignment algorithm are given. Simulation results show that the new algorithm is feasible and effective.
基金Supported by the 100 Top-Talents Program of Chinese Academic of Sciences (No. 99M2008M02)
文摘We investigate the problem of how to minimize the energy consumption in multi-hop Wireless Sensor Network (WSN),under the constraint of end-to-end reliability Quality of Seervice (QoS) requirement.Based on the investigation,we jointly consider the routing,relay selection and power allocation algorithm,and present a novel distributed cross-layer strategy using opportunistic relaying scheme for cooperative communication.The results show that under the same QoS requirement,the proposed cross-layer strategy performs better than other cross-layer cooperative communication algorithms in energy efficiency.We also investigated the impact of several parameters on the energy efficiency of the cooperative communication in WSNs,thus can be used to provide guidelines to decide when and how to apply cooperation for a given setup.
文摘System integrity is important for fast and accurate measurement and control.LabVIEW is widely used in education and industry.Many LabVIEW codes are hard to be read and shown because of their 2D topology.In order to simplify the programming,a 4-layer model of developing sensor or measurement systems with LabVIEW is proposed in this paper.The purpose of this paper is to show the readers how to design simple,clear and strong automated systems with LabVIEW.Using a Sensirion SHT75 humidity sensor and an NI USB6008 DAQ board as an example,this paper describes the steps of developing a sensor system from the physical layer to application layer in detail.In layer 2,port selection and signal regulation are demonstrated.In layer 3,timing waveform analysis and synthesis,state diagram analysis,instruction set design,micro operation and fault tolerance designs are demonstrated.In layer 4,data visualization is covered with a vivid example.Programmers found it was hard to show readers their LabVIEW codes because many LabVIEW codes occupy several screens.A layer model simplifies the programming,so one is able to show a medium size LabVIEW code easily.
文摘This paper presents a wireless sensor network (WSN) access control algorithm designed to minimize WSN node energy consumption. Based on slotted ALOHA protocol, this algorithm incorporates the power control of physical layer, the transmitting probability of medium access control (MAC) layer, and the automatic repeat request (ARQ) of link layer. In this algorithm, a cross-layer optimization is preformed to minimizing the energy consuming per bit. Through theory deducing, the transmitting probability and transmitting power level is determined, and the relationship between energy consuming per bit and throughput per node is provided. Analytical results show that the cross-layer algorithm results in a significant energy savings relative to layered design subject to the same throughput per node, and the energy saving is extraordinary in the low throughput region.
基金Supported by National Natural Science Foundation of P. R. China (60374072, 60434030)
文摘Lossy link is one of the unique characteristics in random-deployed sensor networks. We envision that robustness and reliability of routing cannot be ensured purely in network layer. Our idea is to enhance the performance of routing protocol by cross-layer interaction. We modified mint protocol, a routing protocol in TinyOS and proposed an enhanced version of mint called PA-mint. A transmission power control interface is added to network layer in PA-mint. When routing performance of the current network is not satisfied, PA-mint monotonically increases the transmission power via the interface we added. PA-mint is able to connect orphan nodes and robust to node mobility or key nodes failure. In the case that automatic request retransmission is employed, the number of retransmissions can be reduced by PA-mint. Results from experiments show that PA-mint increases the reliability and robustness of routing protocol by cross-layer interaction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11547183 and 11547241)the Higher Education and High-quality and World-class Universities,China(Grant No.PY201612)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFB0302003)the Natural Science Foundation of Beijing(Grant No.2162033)
文摘A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit （FOM） depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 （or AlAs） absentee layer is 1.059% （or 2.587%） higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.
文摘Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.
基金partially supported by the National Natural Foundation of China under Grant No.61176066 and No.61101031
文摘Abstract--Poly4-vinylphenol （P4VP）/multi-wan carbon nanotubes （MWNTs） multi-layer sensitive films were deposited on interdigitated electrodes by airbrush technology to detect toluene vapor at room temperature. The surface and section morphologies of the multi-layer films were observed by a scanning electron microscope （SEM）. It is found that the resistance of the sensor increases when it is exposed to toluene vapor and the response has a good linearity with the concentration of toluene. The results show that the P4VP/MWNTs three-layer film sensors have better sensing properties compared with the two-layer film sensors. The related sensing mechanism is studied in detail.
文摘The main research objective in wireless sensor networks (WSN) domain is to develop algorithms and protocols to ensure minimal energy consumption with maximum network lifetime. In this paper, we propose a novel design for energy harvesting sensor node and cross-layered MAC protocol using three adjacent layers (Physical, MAC and Network) to economize energy for WSN. The basic idea behind our protocol is to re-energize the neighboring nodes using the radio frequency (RF) energy transmitted by the active nodes. This can be achieved by designing new energy harvesting sensor node and redesigning the MAC protocol. The results show that the proposed cross layer CL_EHSN improves the life time of the WSN by 40%.
文摘In this work, we have developed an electrochemical sensor for nitrite detection, based on a polyoxometalate (POM) namely mono-lacunary keggin anion [SiW11O39]8﹣ cited as (SiW11). Electrochemical characterization of SiW11 shows two-step reduction processes, with formal potentials of ﹣0.5 V (I) and ﹣0.68 V (II). Oppositely charged polyelectrolyte (poly (allylamine hydrochloride) (PAH)) and (SiW11) were assembled alternately to modify glassy carbon electrode. The electrochemical behavior of the modified electrode was studied in detail using cyclic voltammetry (CV). The results showed that SiW11/PAH/GC electrode present good electrocatalytic activity for the reduction of nitrite. The sensor showed a dynamic range from 100 μM to 3.6 mMof nitrite and no interference from other classical anions. Experimental factors that affect electron-transfer rate in these films, such as pH effect and layers number, were systematically analyzed.
文摘Several protocols and schemes have been proposed to reduce energy consumption in Wireless Sensor Net-works (WSNs). In this paper we employ farcoopt, a cross layer design approach with the concept of coop-eration among the nodes with best farthest neighbor scheme to increase the Quality of Service (QoS), reduce energy consumption, increases performance and end-to-end throughput. We present cooperative transmission to connect previously disconnect parts of a network thus overcoming the separation problem of multi-hop network. We show that this approach improves connectivity over 50% compared to multi-hop approaches and reduces the number of nodes necessary to provide full coverage of an area up to 35%. Simulation results show that on increase of data rates i.e. packet the network life time increases in farcoopt as compared to tra-ditional multi hop approach. The result of this analysis is presented in this work.
文摘The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments. A kind of simple structure, small size, good stability, high sensitivity chemical concentration sensor is obtained.
文摘Researches related to wireless sensor networks primarily concentrate on Routing, Location Services, Data Aggregation and Energy Calculation Methods. Due to the heterogeneity of sensor networks using the web architecture, cross layer mechanism can be implemented for integrating multiple resources. Framework for Sensor Web using the cross layer scheduling mechanisms in the grid environment is proposed in this paper. The resource discovery and the energy efficient data aggregation schemes are used to improvise the effective utilization capability in the Sensor Web. To collaborate with multiple resources environment, the grid computing concept is integrated with sensor web. Resource discovery and the scheduling schemes in the grid architecture are organized using the medium access control protocol. The various cross layer metrics proposed are Memory Awareness, Task Awareness and Energy Awareness. Based on these metrics, the parameters-Node Waiting Status, Used CPU Status, Average System Utilization, Average Utilization per Cluster, Cluster Usage per Hour and Node Energy Status are determined for the integrated heterogeneous WSN with sensor web in Grid Environment. From the comparative analysis, it is shown that sensor grid architecture with middleware framework has better resource awareness than the normal sensor network architectures.
文摘We consider the extension of network lifetime of battery driven wireless sensor networks by splitting the sensing area into uniform clusters and implementing heterogeneous modulation schemes at different members of the clusters. A cross-layer optimization has been proposed to reduce total energy expenditure of the network;at network layer, routing is done through uniform clusters;at MAC layer, each sensor node of the cluster is assigned fixed or variable time slots and at physical layer different member of the clusters is assigned different modulation techniques. MATLAB simulation proved substantial network lifetime gains.
文摘Rapid penetration of small customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. Offering precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However offering some better QoS for wireless multimedia over sensor networks raises significant challenges. In this paper, we propose an adaptive Cross-Layer multi-channel QoS-MAC protocol to support energy-efficient, high throughput, and reliable data transmission in Wireless Multimedia Sensor Network (WMSNs). Our proposed protocol use benefit of TDMA and CSMA/CA to adaptively assign channels and timeslots to active multimedia sensor nodes in clusters. Simulations show that the proposed system achieves the performance objectives of WMSNs with increased network throughput at the cost of a small control and energy overhead.
基金the National Natural Science Foundation of China(No.60777038).
文摘Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.
文摘A coating scheme was developed for enabling the operation of a GaAs-based Molecular Controlled Semiconductor Resistor (MOCSER) under biological conditions. Usually GaAs is susceptible to etching in an aqueous environment. Several methods of protecting the semiconductor based devices were suggested previously. However, even when protected, it is very difficult to ensure the operation of a GaAs-based electronic sensor in aqua solution for long periods. We developed a new depositing scheme of (3-mercaptopropyl)-trimethoxysilane (MPTMS) on GaAs substrate consisting of two separate steps. The first involves chemisorption of a dense primary MPTMS layer on the substrate, whereas in the second, a thin MPTMS polymer layer is deposited on the already adsorbed layer, resulting in a 15 -?29 nm thick coating. We show that applying the new MPTMS deposition procedure to GaAs-based MOCSER devices allows up to 15 hours of continuous electrical measurements and stable performance of the sensing device in harsh biological environment. The new protection allows implementing GaAs technology in bioelectronics, particularly in biosensing.
