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Transmission power control has been extensively used not only to save energy,but also to improve the network throughput in wireless ad hoc networks. A new adaptive power control algorithm,i.e.,PCMAC algorithm,based on IEEE 802.11 DCF protocol for Vehicular Ad hoc networks is proposed. According to the communication status,the algorithm dynamically adjusts the transmit powers of the CTS frames of receiving nodes and the data packets of the transmitting nodes,furthermore,adjusts the transmit powers of the RTS frames of the transmitting nodes according to the optimal number of access nodes such that the network throughput is maximized,in order to avoid conflicts and increase throughput. The simulation results show that the proposed PCMAC (power control media access control)algorithm can not only decrease the average energy consumption so as to prolong the lifetime of the network,but also improve spatial reuse of the wireless channel so as to improve the average throughput of the network. 相似文献
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For the high density of distributed heterogeneity nodes in wireless sensor networks (WSNs), the optimal sensor deployment is studied. A cost optimal heterogeneous sensor deployment scheme based on genetic algorithm is proposed. The cost of sensor node deployment is used as objective function for optimization computation subjected to network coverage and fault tolerance to obtain the suitable types and positions of the sensors. The algorithm can be used for boolean sensing model as well as probabilistic sensing model. The simulation results demonstrate that the proposed algorithm converges fast toward the optimal solutions and reduces the cost of sensor deployment, which is feasible for heterogenous nodes deployment in WSNs. 相似文献
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As a result of combination of microsensor technology,low power computing and wireless networking,wireless sensor networks become an active branch in scientific territory of computer science at the moment.The recent reserch work on data management of wireless sensor networks is mainly introduced. In order to achieve high performance of the data-center network system,and supply an effective sensor database administration processing system in the interest of observing person or consumer,Separately proposed valid settlement schemes for the two key problems in database technology: data model and query processing. 相似文献
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In wireless sensor networks that consist of a large number of low-power sensors.Because the sensor's energy is limited,one of the main design is to obtain long system lifetime.The authors firstly analyse LEACH and LEACH-C clustering routing for wireless sensor networks.Aimming at their shortcoming,they present a new routing LEACH-NEW.This routing uses multi ho Pinstead of one hop.At last,they use NS2 to simulate them.Simulation show results that new routing exhibits noticeably longer system lifetime than rouing LEACH and LEACH-C. 相似文献
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In wireless sensor network, routing protocols which based on clustering have the advantages of energy consumption, topology management and data fusion. The HEED protocol, which generates cluster heads based on distributed algorithm, drives up the rate of clustering and creates well distributed cluster heads. However, it does not consider the mobility of nodes in the network. When the distance between neighbor nodes has changed, the AMRP method which decides the node belongs to different cluster heads would cause problems such as high energy consumption, short lifetime of network and so on. Responding to these problems, the paper proposes the S HEED, a clustering algorithm based on stability, which chooses the stability as a parameter of nodes when choosing a cluster head. With S HEED algorithm, the high energy consumption problem among cluster nodes and cluster heads caused by the mobility is tackled. The simulation experiment demonstrates that the S HEED algorithm lower the energy consumption of cluster heads and prolongs the network lifetime. 相似文献
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The follow-up application of underwater wireless sensor network is influenced by accuracy of self-localization of nodes. The self-localization of nodes is discussed in this paper. First of all, nodes of underwater wireless sensor network are classified into several levels according to the accuracy of position of nodes and the levels are from the first to the fifth in accordance with accuracy of nodes from high to low respectively. Secondly, the level of anchor nodes can be known by those unknown nodes from the information given by the anchor nodes themselves, At the same time the unknown nodes are able to be located in the area controlled by the first level of anchor nodes that are as the aggregation. Then the positioning algorithm is designed correspondingly in accordance with the accuracy level of nodes. Finally, the positioning algorithm is simulated and analyzed. The result shows that the unknown nodes can be located effectively by hierarchical control. 相似文献
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The equivalence between fuzzy neural networks model for max-min fuzzy operator and S.Stoeva's is proved by studying the fuzzy neural networks model for max-min fuzzy based on S.Stoeva's.Then the paper proposes the fuzzy backpropagation learning algorithms for changing fuzzy power and probes their convergence properties.Finally,it simulates experiment such as state monitoring of turbo-generator set.The results show that the fuzzy backpropagation learning algorithms presented are convergent on condition that the output of training sample is between maximum and minimum of its input. 相似文献
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Recent advanced sensor technology has enabled wireless smart sensor network (WSSN) for structural health monitoring (SHM). Because of many attractive features such as wireless communication, battery powered, on board computation, and low cost, the WSSN makes the dense array of sensors feasible for engineering practice.In this study, a method for fatigue life monitoring using wireless smart sensor networks is explored by implementing Rainflow cycle counting algorithm in the sensor network, which extracts the loading features including the number of each load cycles, amplitude and mean of strain.Instead of sending back raw strain data to basestation, only the onboard processed histogram of the strain data is transmitted, which tremendously reduces the amount of data and the associated energy consumption in the wireless smart sensor networks.In addition, the feasibility of the method is experimentally verified through lab-scale tests. 相似文献
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Adaptive relay selection algorithm in decode-and-forward cooperative communication networks 
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下载免费PDF全文 An adaptive relay selection algorithm(ARS) is proposed to optimize the performance of decode-and-forward cooperative communication networks, both system outage probability and average numbers of cooperative relays are analyzed. When the direct transmission between source and destination is fail, according to the channel quality, the destination orders relay nodes in the decode set, and the ordered relays are included in cooperation in turn until the instantaneous received SNR at destination is not smaller than the preset SNR threshold. Simulation results show that, the proposed algorithm can get optimal outage performance, decrease the average numbers of cooperative relays efficiently, to incrense bandwidth efficiency and reduce system overhead. 相似文献
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Most real power systems are not radial networks and evaluation of the stability often needs to establish electromagnetic transient simulation models. So the network equivalent is required first and foremost. The adjacent two-node equivalent method, which considers the coupling impedance between equivalent nodes, is used to realize the simplification and modeling to complex power grid. The analysis and simulation on both the HVDC system from Deyang to Baoji and a real extra-high voltage AC transmission system in South China shows that the static performance of the simulated system by using the adjacent two-node equivalent method is completely equivalent to the original one, as well as the performance of dynamic equivalent is in a satisfied level. Thus the transient system model simplified can be well established to support research of power grid’s security and stability. 相似文献
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It is an important way for co production efficiency improvement and system robustness to deeply understand the relationship between the structure and function of interfirm collaborative production networks (ICPN) . This paper develops the topological model for ICPN based on the analysis of the characteristics of interfirm collaborative production modes. By introducing complex networks, a case of Polyurethane industry is simulated. The results show that ICPN has the characteristics of small world, scale free and centralities of nodes. Moreover, complex network characteristics affect the capability and efficiency of production system. 相似文献
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In the simulation of building energy consumption and solar energy system design, hourly direct and diffuse radiation is one of the most important basic parameters.While, due to Chinese solar radiation data missing, it is difficult to obtain hourly direct and diffuse radiation data. Many domestic and foreign scholars has studied and put forward several diffuse radiation models. 2009-2011 year's measured data of total solar radiation and diffuse radiation were scleted and five typical separation models, that is Erbs model, Orglill and Hollands model,stochastic climatic model, Zhang Qingyuan model,were put to analyze and compare the measured data and the simulation data between the correlation coefficient, root mean square error and relative error. Found that Erbs model predicts diffuse radiation with the highest accuracy, followed by the Zhang Qingyuan model and Orglill and Hollands model, Clearness index Kt can be used as the main influence factor. 相似文献
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In view of the different of the underground heat storage water tank of solar position arrangement, make use of the Fluent software program numerical simulation and calculation, it is concluded that under different conditions the heat storage water tank temperature field distribution of the soil around. At the same time, establishing physical model and mathematical model of underground heat storage water tank and combined with practical engineering, verify the underground storage tank for heat and energy storage, to obtain the relationship between the tank roof loss and total heat release. Calculation results show that under the same conditions, outdoor storage tank at the top of the heat dissipating capacity to reduce, so the method can be used to offset at the top of the energy required collector to reduce, so the method can be used to offset this part of the energy required collector area of the cut, improve thermal efficiency and reduce the user store hot water tank of the store. 相似文献
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By analyzing the reason that why the existing routing protocols cannot be applied to the wireless sensor networks for bridge health monitoring, a new routing protocol is proposed. Since the locations of the collecting modules are fixed, the proposed protocol exchanges the routing information between the neighbor nodes by adjusting the exchange cycle according to reliability of the modules. For the low routing security requirement, while to increase the routing efficient, the middle nodes replying the routing requirements with variable thresholds is introduced. In order to make full use of information in route discovering procedure, the backup routes mechanism is adopted. The proposed protocol can efficiently forward data and is suitable for the bridge health monitoring. 相似文献
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Based on the electromagnetic theory and the work principle of electromagnetic parking brake,a new structure power breaker electromagnetic brake is designed,which is low energy consumption and embedded in in wheel motor,and a kind of analysis computation method is proposed. Through the analysis of magnetic circuit of electromagnetic brake,the mathematical model is established. A three dimensional finite element model is established via Ansoft software with the purpose of analyzing the electromagnetic property and work performance of electromagnetic brake,as well as simulating the dynamic work process of electromagnetic brake. By profoundly investigating the intricate internal magnetic field strength and power density distribution of the electromagnetic brake,the current research has obtained the exciting coil with time curve,electromagnetic force with work air gap curve and the armature displacement with time curve,etc. The conformity of the final simulation results with the experimental data indicates that the electromagnetic finite element method is accurate and reliable to analyze the electromagnetic property of electromagnetic brake,which can meet the requirements of sensitivity,reliability and specialization in electric scooter parking brake system. 相似文献
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The principle of the energy equilibrium is applied to establish the relationship between heat loss and supply, indoor and outdoor temperature, supply and return water temperature of heating system for a building. A numerical simulation model of supply-return water temperature is deduced. The heating system mathmatical model for the office building in Beijing area is developed Based on the hourly air temperatures at the automatic weather observation station and observed indoor temperature from the office building in February 2010 in Beijing area,a simulation experiment of hourly prediction for next 24-hours is executed. The test results show that the simulated and observed supply and return water temperature changed significantly when the outdoor air temperature changes, it is inversely proportional relationship between them, the correlation coefficient is -0.95, the simulated indoor temperature has remained near the designed temperature. There is a consistent trend between simulated and observed heating, as outdoor air temperatures rise, the simulated heating declined, it can save nearly 8 % for heating. This means the simulated model of supply-return water temperature has a good quality. 相似文献
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Temperature-depended resistivity of carbon nanotube film is measured and the results show negative temperature effect because the resistivity is decreased as the temperature increased. An electronic transport model for the carbon nanotube film is set up and the resistivity calculation formula is deduced, whose calculating result is compared with experimental datum. It shows that theoretical calculation is well contented with experiment results. Then, the relationship between resistivity and diameter of the carbon nanotube is discussed. 相似文献
19.
Discussion about Saving Energy in Refrigeratory 总被引：1，自引：0，他引：1
Food refrigeration is regarded as a high energy consuming trade. Under the long period system of state operated enterprise,there are many phenomenons of ignoring energy management and wasting energy. Energy consuming is not very clear for production.Consuming in our country is far more than the international standard and there is a distance between the middle_westland and the eastland. As a enterprise that faces the international market,it is important for it to strength the management so that the cost can be reduced. Considering those phenomenons of ignoring energy management and wasting energy in refrigeratory at present, some measures such as improved the unreasonable operation process, strengthening the energy management and automation to realize automatizing operation are improved to reduce the cost for refrigeratory trades. 相似文献
20.
Aiming at the shortcomings of the existing RSS(received signal strength) based localization algorithm for wireless sensor networks (WSN), a cooperative localization algorithm (CLA) is proposed. A reference anchor node is introduced to tolerant some minor error including the node position error. Dixon detection method is applied to remove abnormal RSS values, while the standard deviation threshold of RSS and learning model are introduced to reduce the RSS ranging error and effectively improve the precision. Simulation experiments are performed to evaluate the performance of the proposed algorithm. The results demonstrate that the localization accuracy is improved effectively, while the stability and robustness are better. 相似文献