基于ZigBee的电气设备无线监测系统的设计

针对变电站现有的设备监测系统采用有线连接方式,成本高且现场不易施工的特点,提出了基于ZigBee技术的无线监测系统.在分析ZigBee技术的基础上,介绍了系统构成及原理,确定了ZigBee网络结构以及传感器节点的软、硬件功能设计.所设计的基于ZigBee的无线监测系统在变电站设备状态监测中具有较好的应用前景.     

用于环境监测的ZigBee无线传感器节点设计

温室环境监测采用基于ZigBee技术的智能网络化传感器有着很明显的优势。ZigBee网络容量大、功耗低、易于扩充并且支持自组织组网。该文设计了一种ZigBee无线传感器监测节点,介绍了基于ZigBee协议构建的无线数据采集网络,包括传感器节点的软、硬件设计。实验证明：节点工作状况良好,整个网络具有较高的可行性,可以实现对环境温湿度、光强等信息进行实时、准确的监测。     

无人值守放牧监测系统报警准确率的研究

通过ZigBee技术、GPS定位追踪技术和远程无线通信技术的结合,计算了ZigBee节点传输距离,并提出一种双系统的监测牛群数量的策略,通过对系统误报率的分析,设定误报率门限,从而确定双系统的组成方式,提高牛群数量监测的准确性,降低误警概率.在此基础上设计了一套智能牛群检测系统,并通过实验验证了理论计算结果.该系统可以在无人值守的情况下,自动监测草原牧场上牛群数量并记录牛群位置,实现自动上传功能.     

基于ZigBee技术的无线传感器网络及其应用研究

无线传感网络是当前国内外传感器技术领域的热点研究课题,着重研究了基于ZigBee技术的无线传感器网络节点的软硬件设计,实现了ZigBee无线传感器网络节点的设计,并运用该无线传感节点建立了基于ZigBee技术的无线结构健康监测系统,利用模式匹配的方法实现了基于无线传感器网络的载荷定位和结构紧固件失效的实时监测.     

基于物联网的罗氏沼虾养殖智能监测系统的设计

针对罗氏沼虾养殖环境的智能监测要求,以智能检测、无线传感网络、GPRS无线通信等技术为支撑,提出一种基于物联网的罗氏沼虾养殖智能实时监测系统.系统以ZigBee无线组网为基础,由分布养殖水域中的传感器节点采集罗氏沼虾养殖要素参数(pH值、溶氧量、水温、水位等),通过ZigBee网络将其传送至汇聚节点,再利用GPRS实现监测数据的远程传输,并通过互联网发布监测结果.测试表明,系统满足罗氏沼虾养殖水质的智能化、实时化监测的需求,最终实现罗氏沼虾养殖的智能监测.     

基于ZigBee无线网络技术的避雷器在线监测传感器设计

为了及时发现交流高压避雷器的受潮、老化和其他隐患,避免因事故造成巨大经济损失,对高压避雷器在线监测传感器进行了研究.针对基于ZigBee无线网络技术的避雷器在线监测传感器在兰溪(芝堰)变电站智能化改造中的应用,详细介绍避雷器在线监测传感器工作原理,ZigBee网络组网方式.该传感器可实现变电站内避雷器泄露电流,阻性电流...     

ZigBee技术在智能箱式变电站中的应用

简单分析了现有箱式变电站中存在的技术问题,介绍了ZigBee技术的特点和优势。将ZigBee技术应用于箱式变电站,给出了无线通讯技术的硬件电路和软件方案,设计了基于ZigBee技术的智能箱式变电站。根据所设计的变电站配电运行表明,将无线ZigBee技术应用于箱式变电站,可以实现箱式变电站的智能化,同时该变电站还具有低成本、低功耗、实时性及可靠性高等特点。     

ZigBee和GPRS技术在水文监测系统中的应用研究

结合ZigBee和GPRS技术的特点和优势,提出了一种无线水文监测系统解决方案。重点分析了网络协调器节点的软件设计,包括ZigBee协议和GPRS网络连接的实现方法以及ZigBee和GPRS网络数据转换任务的设计。     

基于无线传感器网络的楼宇环境监测系统设计

设计了基于无线传感器网络技术的楼宇温湿度监测系统.该系统完成对各室内温湿度光强数据的采集、传输、存储、分析,具有低功耗、自组织特点.管理节点利用ZigBee网络,根据管理中心的要求发送无线传感器网络各节点温湿度光强数据及报警信息.实验结果表明,ZigBee技术以其低功耗、低成本、网络容童大的特点,在实现实时楼宇环境监测方面有很大的优势,可满足中央空调系统对楼宇温湿度光强的监测需求.     

基于ZigBee的森林防火系统设计

基于ZigBee无线传感器网络技术,设计了森林防火系统.系统实时采集监测区域的温度、湿度和烟雾浓度等数据,并监测及有效控制森林火情.本文介绍了ZigBee技术,阐述了系统的总体设计,硬件和软计实现方法.通过试验,节点的灵敏度和网络传输达到了理想效果.     

Functional Trees

In the context of classification problems, algorithms that generate multivariate trees are able to explore multiple representation languages by using decision tests based on a combination of attributes. In the regression setting, model trees algorithms explore multiple representation languages but using linear models at leaf nodes. In this work we study the effects of using combinations of attributes at decision nodes, leaf nodes, or both nodes and leaves in regression and classification tree learning. In order to study the use of functional nodes at different places and for different types of modeling, we introduce a simple unifying framework for multivariate tree learning. This framework combines a univariate decision tree with a linear function by means of constructive induction. Decision trees derived from the framework are able to use decision nodes with multivariate tests, and leaf nodes that make predictions using linear functions. Multivariate decision nodes are built when growing the tree, while functional leaves are built when pruning the tree. We experimentally evaluate a univariate tree, a multivariate tree using linear combinations at inner and leaf nodes, and two simplified versions restricting linear combinations to inner nodes and leaves. The experimental evaluation shows that all functional trees variants exhibit similar performance, with advantages in different datasets. In this study there is a marginal advantage of the full model. These results lead us to study the role of functional leaves and nodes. We use the bias-variance decomposition of the error, cluster analysis, and learning curves as tools for analysis. We observe that in the datasets under study and for classification and regression, the use of multivariate decision nodes has more impact in the bias component of the error, while the use of multivariate decision leaves has more impact in the variance component.     

The impact of mobility on the geocasting problem in mobile ad-hoc networks: Solvability and cost

We present a model of a mobile ad-hoc network in which nodes can move arbitrarily on the plane with some bounded speed. We show that without any assumption on some topological stability, it is impossible to solve the geocast problem deterministically despite connectivity and no matter how slowly the nodes move. Moreover, even if each node maintains a stable connection with each of its neighbors for some period of time, it is impossible to solve the geocast problem if nodes move too fast. Additionally, we give a tradeoff lower bound which shows that the faster the nodes can move on a monodimensional space, the more costly it would be to solve the geocast problem. We provide geocasting algorithms for the case where nodes move in one dimension and also when they can move on the plane (i.e., in two dimensions). We prove correctness of our algorithms by giving exact bounds on the speed of movement. Our analysis helps understand the impact of speed of nodes, firstly, on geocasting solvability and, secondly, on the cost of geocasting.     

Algebraic method of simplifying Boolean networks using semi‐tensor product of Matrices

The huge state space of large Boolean networks makes analysis and synthesis difficult. This paper, using a new matrix analysis tool called semi‐tensor product of matrices, to explain a simplification method of Boolean networks in a mathematical manner. The idea consists of two steps. First, remove the nodes whose logical dynamics are independent of themselves directly; second, use the logical functions (LFs) of the removed nodes to substitute for their corresponding variables in the LFs of other nodes; such nodes evolve directly with both themselves and the removed nodes. We discover that the simplified and original Boolean networks share some important topological structures such as attractor cycles, steady states and paths. An algebraic algorithm is provided to find all of the cycles and steady states of simplified Boolean networks. Finally we apply the results to the metastatic melanoma network to check the effect of the simplification method.     

Analytical modeling and mitigation techniques for the energy hole problem in sensor networks

In this paper we investigate the problem of uneven energy consumption in a large class of many-to-one sensor networks. In a many-to-one sensor network, all sensor nodes generate constant bit rate (CBR) data and send them to a single sink via multihop transmissions. This type of sensor network has many potential applications such as environmental monitoring and data gathering. Based on the observation that sensor nodes sitting around the sink need to relay more traffic compared to other nodes in outer sub-regions, our analysis verifies that nodes in inner rings suffer much faster energy consumption rates (ECR) and thus have much shorter expected lifetimes. We term this phenomenon of uneven energy consumption rates as the “energy hole” problem, which may result in severe consequences such as early dysfunction of the entire network. We proposed analytical modeling for this problem, which can help understand the relevance of different factors on energy consumption rates. Using this model, we study the effectiveness of several existing approaches towards mitigating the “energy hole” problem, including deployment assistance, traffic compression and aggregation. We have used simulation results to validate our analysis.     

Superelements Modelling in Flexible Multibody Dynamics

We present a new implementation of substructuring methods forflexible multibody analysis. In previous developed formulations, wefixed the local axes of the superelement to one node. In thisformulation, the reference frame is floating and close, in some sense,to the body center. The local frame is selected based on the positionsof the interface nodes of the superelement, and completely independentof the order in which the nodes of the superelement are given.Therefore, the superelement itself depends only on the nodes positions,and on the mass and stiffness properties, thus allowing a very easyinterfacing between the finite element program which computed thesuperelement and the mechanism analysis program.     

A generative model for graph matching and embedding

This paper shows how to construct a generative model for graph structure through the embedding of the nodes of the graph in a vector space. We commence from a sample of graphs where the correspondences between nodes are unknown ab initio. We also work with graphs where there may be structural differences present, i.e. variations in the number of nodes in each graph and their edge structure. We characterise the graphs using the heat-kernel, and this is obtained by exponentiating the Laplacian eigensystem with time. The idea underpinning the method is to embed the nodes of the graphs into a vector space by performing a Young-Householder decomposition of the heat-kernel into an inner product of node co-ordinate matrices. The co-ordinates of the nodes are determined by the eigenvalues and eigenvectors of the Laplacian matrix, together with a time-parameter which can be used to scale the embedding. Node correspondences are located by applying Scott and Longuet-Higgins algorithm to the embedded nodes. We capture variations in graph structure using the covariance matrix for corresponding embedded point positions. We construct a point-distribution model for the embedded node positions using the eigenvalues and eigenvectors of the covariance matrix. We show how to use this model to both project individual graphs into the eigenspace of the point position covariance matrix and how to fit the model to potentially noisy graphs to reconstruct the Laplacian matrix. We illustrate the utility of the resulting method for shape analysis using data from the Caltech–Oxford and COIL databases.     

A secure credit-based cooperation stimulating mechanism for MANETs using hash chains

One of the most challenging problems in self-organized mobile ad hoc networks (MANETs), which consist of autonomous and self-interested nodes, is to stimulate the nodes to cooperate in routing and packet forwarding. In this paper, we propose a novel credit-based cooperation mechanism that utilizes hash chains on messages to defend against cheating by the nodes. We show that it imposes a low workload on the nodes in comparison with the mechanisms that deploy digital signature schemes. Moreover, through a game-theoretic analysis, it is shown that any level of cooperation by a node will be attainable if the mechanism makes appropriate payments.     

Trust-based security for the OLSR routing protocol

The trust is always present implicitly in the protocols based on cooperation, in particular, between the entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and the entire network. In our work, we are interested by trust as security solution for OLSR protocol. This approach fits particularly with characteristics of ad hoc networks. Moreover, the explicit trust management allows entities to reason with and about trust, and to take decisions regarding other entities.In this paper, we detail the techniques and the contributions in trust-based security in OLSR. We present trust-based analysis of the OLSR protocol using trust specification language, and we show how trust-based reasoning can allow each node to evaluate the behavior of the other nodes. After the detection of misbehaving nodes, we propose solutions of prevention and countermeasures to resolve the situations of inconsistency, and counter the malicious nodes. We demonstrate the effectiveness of our solution taking different simulated attacks scenarios. Our approach brings few modifications and is still compatible with the bare OLSR.     

On the lifetime of node-to-node communication in wireless ad hoc networks

Lifetime of node-to-node communication in a wireless ad hoc network is defined as the duration that two nodes can communicate with each other. Failure of the two nodes or failure of the last available route between them ends their communication. In this paper, we analyze the maximum lifetime of node-to-node communication in static ad hoc networks when alternative routes that keep the two nodes connected to each other are node-disjoint. We target ad hoc networks with random topology modeled as a random geometric graph. The analysis is provided for (1) networks that support automatic repeat request (ARQ) at the medium access control level and (2) networks that do not support ARQ. On the basis of this analysis, we propose numerical algorithms to predict at each moment of network operation, the maximum duration that two nodes can still communicate with each other. Then, we derive a closed-form expression for the expected value of maximum node-to-node communication lifetime in the network. As a byproduct of our analysis, we also derive upper and lower bounds on the lifetime of node-disjoint routes in static ad hoc networks. We verify the accuracy of our analysis using extensive simulation studies.     

Bounded disorder file organization

The bounded disorder file organization proposed by W. Litwin and D.B. Lomet (1987) uses a combination of hashing and tree indexing. Lomet provided an approximate analysis with the mention of the difficulty involved in exact modeling of data nodes, which motivated this work. In an earlier paper (M.V. Ramakrishna and P. Mukhopadhyay, 1988) we provided an exact model and analysis of the data nodes, which is based on the solution of a classical sequential occupancy problem. After summarizing the analysis of data nodes, an alternate file growth method based on repeated trials using universal hashing is proposed and analyzed. We conclude that the alternate file growth method provides simplicity and significant improvement in storage utilization