Wireless sensor networks (WSN) are considered to be the key-enabler for low cost highly distributed applications in the area of homeland security, healthcare, environmental monitoring etc. A necessary prerequisite is ...
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Wireless sensor networks (WSN) are considered to be the key-enabler for low cost highly distributed applications in the area of homeland security, healthcare, environmental monitoring etc. A necessary prerequisite is reliable and efficient event detection. this paper introduces a novel approach for event configuration and in network processing, called event decision trees (EDT). An EDT enables every node to self-divide event queries according to its resources. EDT autonomously adapt to the tasks assigned, even though it requires to organize collaboration between nodes to deliver expected results. the effort for maintain formal EDT is evaluated by analysis and simulations. Our results show that the proposed lease-based mechanism for maintaining producer/consumer pairs in an EDT outperforms even idealized acknowledgment-based approaches.
Usually, LPF (low pass filter) is used in the feedback loop of SRF(Synchronous Reference Frame) - PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. In th...
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Usually, LPF (low pass filter) is used in the feedback loop of SRF(Synchronous Reference Frame) - PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. In this paper, it is shown that the cut-off frequency of the LPF should be designed to suppress the harmonic ripples contained in the measured voltage. Also, a new design method of the loop gain of the PI-type controller in the SRF-PLL is proposed withthe consideration of the dynamics of the LPF. As a result, a better transient response can be obtained withthe proposed design method. the LPF frequency and PI controller gain are designed in coordination according to the steady state and dynamic performance requirement. this paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the lab-scale experiments.
this paper addresses the problem of coordination path following control of multiple autonomous vehicles. Stated briefly, the problem consists in steering a group of vehicles along a specified paths, while holding a de...
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this paper addresses the problem of coordination path following control of multiple autonomous vehicles. Stated briefly, the problem consists in steering a group of vehicles along a specified paths, while holding a desired inter-ship formation pattern. Path-following for each vehicle amounts to reducing an appropriately defined geometric error to zero. We first show a passivity property for the path following system and, next, combine this with a passivity-based synchronization algorithm to coordinate the vehicles along their paths. Vehicle coordination is achieved by adjusting the speed of each vehicle along its path according to information exchanged on the positions of a subset of the other vehicles, as determined by the communication topology adopted. Global stability and convergence of the closed-loop system are guaranteed.
In wireless sensor networks (WSN), energy efficiency is crucial to achieving satisfactory network lifetime. the most commonly used and may be the only efficient method to reduce the energy consumption significantly is...
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ISBN:
(纸本)9781424451142
In wireless sensor networks (WSN), energy efficiency is crucial to achieving satisfactory network lifetime. the most commonly used and may be the only efficient method to reduce the energy consumption significantly is to turn off the radios most of the time, except when it has to participate in data communication. the key challenge is to operate the radio at a low duty cycle but still ensure the delay is relatively low. Various power-saving medium-access control (MAC) protocols have been proposed along this thread. However, most of such protocols focus on a point-to-point communication setting, in which a node will drop an overheard packet if it is not the destination. On the other hand, cooperative wireless communication has been drawing extensive attention in the past few years. Node cooperation has been exploited to reduce end-to-end delay, improve transmission reliability, etc. However, not much has been done in utilizing node cooperation to save energy. this idea may sound absurd since cooperation requires more nodes involved in a communication and would result in more energy being consumed. But is this true? In this paper, we will exploit the possibility of cooperative power saving in wireless ad-hoc networks. the trade-off between energy consumption and delay will be studied. Interestingly, our analytical and simulation results show that cooperation can indeed help achieve a better delay-power consumption trade-off. Our results also show that cooperation together with asymmetric power allocation can achieve the optimal delay-power trade-off.
Network capacity is a critical feature of wireless ad hoc and sensor networks. It is particularly challenging to determine network capacity when combined with other performance objectives such as timeliness. this pape...
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Network capacity is a critical feature of wireless ad hoc and sensor networks. It is particularly challenging to determine network capacity when combined with other performance objectives such as timeliness. this paper investigates real-time capacity for event-driven data-gathering sensor networks withthe unbalanced many-to-one traffic pattern. First, we compute the average allowable throughputs of nodes for a given event distribution, based on which we then leverage results of queuing theory to estimate the per-hop delays. We develop a new slack time distribution scheme for the unbalanced many-to-one traffic pattern, and prove it optimal in terms of the per-hop success probability. Here the per-hop success probability is defined as the probability for a packet to meet its sub-deadlines at each hop. Finally, we define the network-wide real-time capacity, i.e., given a threshold for the per-hop success probability, how much data (in bit per second) can be delivered to the sink node meeting their deadlines. For these research results, we provide some application scenarios, including configuring packet deadlines or verifying a specific deadline configuration, setting a packet's priority for dynamic scheduling, and trading the reliability of real-time data delivery for capacity efficiency etc. We also study two special cases of WSNs, the chain model and the continuous model. Our slack distribution scheme yields consistent or similar results for these two special cases as that of past works, but is more adaptive by supporting more generic cases.
Fast and periodic collection of aggregated data is of considerable interest for mission-critical and continuous monitoring applications in sensor networks. In the many-to-one communication paradigm known as convergeca...
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ISBN:
(纸本)9781424451142
Fast and periodic collection of aggregated data is of considerable interest for mission-critical and continuous monitoring applications in sensor networks. In the many-to-one communication paradigm known as convergecast, we consider scenarios where data packets are aggregated at each hop en route to a sink node along a tree-based routing topology and focus on maximizing the data collection rate at the sink by employing TDMA scheduling and multiple frequency channels. Our key result in the paper lies in proving that minimizing the schedule length for an arbitrary network in the presence of multiple frequencies is NP-hard, and in designing approximation algorithms with worst-case provable performance guarantees for geometric networks. In particular, we design a constant factor approximation for networks modeled as unit disk graphs (UDG) where every node has a uniform transmission range, and a O(Delta(T)log n) approximation for general disk graphs where nodes have different transmission ranges; n is the number of nodes in the network and Delta(T) is the maximum node degree on a given routing tree T. We also prove that a constant factor approximation is achievable on UDG even for unknown routing topologies so long as the maximum node degree in the tree is bounded by a constant. We also show that finding the minimum number of frequencies required to remove all the interfering links in an arbitrary network in NP-hard. We give an upper bound on the maximum number of such frequencies required and propose a polynomial time algorithm that minimizes the schedule length under this scenario. Finally, we evaluate our algorithms through simulations and show various trends in performance for different network parameters.
Embedded complex systems manufacturing becomes more and more a multidisciplinary problem. So complex systems, such as telecommunication systems, control systems, etc., must have a special simulation and validation pro...
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Embedded complex systems manufacturing becomes more and more a multidisciplinary problem. So complex systems, such as telecommunication systems, control systems, etc., must have a special simulation and validation process that mixes both analog and digital circuitry, collects all results from partials and specials simulations to be injected in behavioral models of all system components. Simulation results help us to take decisions; the strength of these decisions is a direct function of the validity of these results. thus the need for efficient and valid simulation models is greater than ever. In this paper we describe some general behavioral models of element of wireless sensors network system, which let us to simulate the entire system in different use cases and all possible architectures using different protocols and technologies in an optimum time.
A primitive gas recognition system which can discriminate limited species of industrial gas was designed and simulated. the dasiaelectronic nosepsila consists of an array of 8 micro-hotplate based SnO 2 thin film gas...
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A primitive gas recognition system which can discriminate limited species of industrial gas was designed and simulated. the dasiaelectronic nosepsila consists of an array of 8 micro-hotplate based SnO 2 thin film gas sensors with different selectivity patterns, signal collecting unit and a signal pattern recognition and decision part in programmable logic device chip. BP (back propagation) neural networks with Multilayer Perceptron structure was designed and implemented on FPGA (field programmable gate array), of twenty thousand gate level chip by VHDL language for processing the input signals from 8 kinds of gas sensors. the network contained eight input units, one hidden layer with 4 neurons and output with 5 regular neurons. the dasiaelectronic nosepsila system successfully discriminated 5 kinds of industrial gases in computer simulation. A small application has been tested on the APS X208 FPGA test board.
Increasing demand for premium electric power, in terms of both quality and reliability, and emerging new energy technologies have led to the development of DG. In the process of connected DG withthe power grid, harmo...
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Increasing demand for premium electric power, in terms of both quality and reliability, and emerging new energy technologies have led to the development of DG. In the process of connected DG withthe power grid, harmonic/inter-harmonic is very serious problem. A new method based on modified MM filter and HHT is proposed to detect harmonic/inter-harmonic caused by the power electric elements. Researched intensively the characteristics of MM transform and MM filter, MM filter is modified aimed at the drawback of selection of structure elements and statistic deflection. HHT is perfectly self-adaptive analysis method. To the signal with harmonic/inter-harmonic, white pulse and positive & negative impulse, firstly, using modified MM filter to remove the white noise, positive & negative impulse and high times harmonic because of its low-passing characteristic, that method's key element is to choosing appropriate SE and its filter effect is better than the wavelet transform. Based on this, using EMD to get a set of IMFs for the denoised signal, the IMFs are almost the single frequency signal. At last, carrying out Hilbert transform to IMFs can get the instantaneous frequency and amplitude of every harmonic/inter-harmonic accurately.
Taiwan is located at the collision boundary of the Philippine sea plate and the Eurasian plate. the mountain terrain is precipitous and the region, on the whole, is characterized by fragile rocks and frequent seismic ...
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Taiwan is located at the collision boundary of the Philippine sea plate and the Eurasian plate. the mountain terrain is precipitous and the region, on the whole, is characterized by fragile rocks and frequent seismic activity. In addition, the concentrated torrential rainfall brought by typhoons cause extensive disasters, debris flow, the most serious disaster caused by torrential rainfall, lead to very heavy casualties in recent years. there are 17 fixed debris flow monitoring stations and 2 mobile stations deployed in Taiwan. However, the whole architecture was designed in late 2000 and implemented by traditional and proprietary methodologies. Hence, several interoperability issues have been unveiled in the recent years when the needs of interoperability increased. In this study, we propose a whole new and open standards based debris flow monitoring architecture following the service oriented architecture (SOA) paradigm. Relevant open geospatial consortium (OGC) standards (for example Web processing service, WPS specification and sensor web enablement, SWE technologies) and advancements from grid computing where lead into the proposed architecture. the use of open standards and distributedcomputing technologies in the proposed architecture enables heterogeneous resources (data, processing and computing power) interoperability. this study also implements an OGC WPS grid processing profile that was developed in the OGC Web services, Phase 6 (OWS-6) initiative of the OGC interoperability program.
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