The sensitivity and stability are mainly factors to hold back the practical applications of Polypyrrole coated fabrics. In this paper, a flexible fabric strain sensor with high sensitivity, good stability and large de...
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ISBN:
(纸本)9781424401390
The sensitivity and stability are mainly factors to hold back the practical applications of Polypyrrole coated fabrics. In this paper, a flexible fabric strain sensor with high sensitivity, good stability and large deformation is reported. It is fabricated by depositing a nano-layer (200nm to 300nm) of polypyrrole on the fabric substrate at low temperature. Thickness and morphology of the conducting thin film on the surface of the fibers were examined by scanning probe microscopy (SPM) and scanning electron microscopy (SENP. The measurement of the conductivity change with strain shows the fabrics so prepared exhibits a high strain sensitivity of similar to 160 for a deformation as large as 50%, while its good stability is indicated by a small loss of conductivity after the thermal and humidity aging tests, and supported by the slight change in conductivity and sensitivity over a storage of eighteen months. The flexible strain sensor is expected to be a promising "soft" smart material with good sensing properties in the preparation of smart garment, wearable hardware and biomedical applications.
We present, a novel dynamic duty cycling scheme to maintain stochastic consistency for caches in sensor networks. To reduce transmissions, base stations often maintain caches for erratically changing sensor sources. S...
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Energy efficiency has been known as the most significant problem in all facets of the wireless sensor network operations. For energy-aware routing scheme for the wireless sensor networks, it is necessary to use sub-op...
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ISBN:
(纸本)0769526160
Energy efficiency has been known as the most significant problem in all facets of the wireless sensor network operations. For energy-aware routing scheme for the wireless sensor networks, it is necessary to use sub-optimal paths occasionally to increase the survivability of networks., In this paper, we present a new network lifetime definition and formulate the energy-aware routing problem with defined network lifetime. And then we propose an energy-aware routing scheme with the node relay willingness for wireless sensor networks. It considers not only to route packets through sensor nodes that have sufficient energy reserves, but also to route packets through light-loaded nodes. Simulation results show that the proposed routing algorithm can achieve longer network lifetime than that of the routing algorithm only considering the energy reserves.
In this paper, we study the fundamental limits of a wireless sensor network's lifetime under connectivity and k-coverage constraints. We consider a wireless sensor network with n sensors deployed independently and...
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The asymptotic upper bound on operational lifetime of time hopping ultra wide band (TH-UWB) wireless sensor network is derived using percolation theory arguments. The operational lifetime is defined as the maximum num...
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ISBN:
(纸本)3540371893
The asymptotic upper bound on operational lifetime of time hopping ultra wide band (TH-UWB) wireless sensor network is derived using percolation theory arguments. The operational lifetime is defined as the maximum number of times the task of delivering certain data to the sink node can be repeated before some node runs out of energy under an initial energy of each sensor node is given. It is shown that for such a static TH-UWB sensor network, which sensor nodes are distributed in a square [0, root S]x[0, root S] according to a Poisson point process of intensity n and each sensor node transmitting R bits data packet to the sink node, the upper bound on the operational lifetime is O(R(-1)S(-alpha/2)n((alpha-1)/2)), where alpha is the path loss exponent. The upper bound shows the operational lifetime increases with node density n/S, thus the large-scale dense TH-UWB wireless sensor network is preferable.
Wireless sensor networks have recently been suggested for many surveillance applications such as object monitoring, path protection, or area coverage. Since the sensors themselves are important and critical objects in...
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A polypyrrole (PPy)-thylakoid bio-chemical sensor for herbicide detection has been successfully demonstrated by monitoring the level of inhibition of photosynthesis activities. Thylakoid isolated from baby spinach was...
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ISBN:
(纸本)9781424401390
A polypyrrole (PPy)-thylakoid bio-chemical sensor for herbicide detection has been successfully demonstrated by monitoring the level of inhibition of photosynthesis activities. Thylakoid isolated from baby spinach was deposit on top of the conductive polypyrrole between two electrodes as the foundation of the chemresistor sensing scheme. The metabolites generated in photosynthesis process changed the conductivity of PPy as the concentration of herbicides changed. Our experiment present ed that the combination of polypyrrole-thylakoid micro-gap structure is sensitive to the herbicide concentration to a measured level as low as 1 mu g/liter of Simazine or 1 part per billion. As such, the micro-gap biosensor based on conductive polymer and sub-cellular plant photosystems provides a new platform suitable for herbicides detection.
An efficient Medium Access Control (MAC) protocol is critical for the performance of a Wireless sensor Network (WSN), especially in terms of energy consumption. In this work we discuss the efficiency of S-MAC, a well-...
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ISBN:
(纸本)0780394100
An efficient Medium Access Control (MAC) protocol is critical for the performance of a Wireless sensor Network (WSN), especially in terms of energy consumption. In this work we discuss the efficiency of S-MAC, a well-known MAC protocol for WSNs, and propose an improvement on the protocol. Via an extensive simulation study considering the cases of both a simple linear topology and a complicated tree topology used for structural health monitoring, the performance evaluation of the enhanced protocol shows that it outperforms the original version of S-MAC in energy conservation.
Advances in wireless networks, mobile devices and location tracking mechanisms are making location-aware applications more and more popular. While several prefetching schemes were proposed for mobile systems, very few...
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ISBN:
(纸本)0769525539
Advances in wireless networks, mobile devices and location tracking mechanisms are making location-aware applications more and more popular. While several prefetching schemes were proposed for mobile systems, very few ones exist for location-dependent applications. And at the best of our knowledge, there is no work describing implementation details of a prefetching scheme for location-dependent systems. In this paper, after a brief survey of information hoarding and prefetching mechanisms, we deduce some requirements for a successful prefetching scheme for location-aware applications, we show that the prefetching policy we previously proposed satisfies these requirements, and we describe a prototype implementing this policy. We describe the system architecture and detailed algorithms describing the tasks executed in the client and the server. We also discuss some additional steps that can be useful for saving energy consumption in the mobile device. An adequate data structure allows the server to have continuously an up to date image of the client's cache content.
The evolution of computers and networks has motivated the development of high performance systems using the distributed system concepts. Such evolution has motivated the study of load balancing techniques, low latency...
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ISBN:
(纸本)0769524664
The evolution of computers and networks has motivated the development of high performance systems using the distributed system concepts. Such evolution has motivated the study of load balancing techniques, low latency protocols, operating systems and middlewares. Furthermore, the evolution from distributedsystems based on clusters to grid environments has motivated new researches to define load balancing algorithms to support scalable and heterogeneous computing capacity environments. In this paper, the Route load balancing algorithm is proposed, presented and evaluated. This algorithm is designed to equally distribute the workload of tasks of parallel applications over Grid computing environments. Experiments compare the performance of the proposed algorithm to others from literature. The obtained results allow to conclude that the Route algorithm is indicated for environments where there are several heterogeneous computers and parallel applications are composed of multiple tasks.
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