The Research On The Parametric Design Of Centrifugal Pump Blade

Ever-advancing in processor brings about fast improvement in the capability of data processing,ever-increasing storage capacity leads to the realization of mass memory. Meanwhile it is noticeable that the collecting method of data lags far away behind and becomes incompatible with above technologies. Integrating computer, wireless communications, sensors, information processing, automatic control, artificial intelligence, and MEMS, Wireless Sensor Networks which attribute to multidisciplinary emerge as the times require. It provided a new method to collect information and process information. WSN is deemed as one of the most important technologies which will affect humanity lives in the future. Whose features that consist of large scale, low power consumption, dynamic topology, self-organization, nodes limited capacity, high redundancy and scalable take advantage of the traditional network technology. Wireless sensor networks has good prospect of potential applications, including the military field, glacier monitoring, health care, precision agriculture, space exploration and so on. Meanwhile other application domain of novelty and valuable will be break. Especially the concept of digital coal and digital oil are proposed, wireless sensor networks has become a new research direction and hot spots of application.Node deployment strategy is the basic problem of Wireless Sensor Networks, which has a great impact to network topology, connectivity, coverage quality and network performance such as life cycle. In large-scale network, there are issues of chances and blind area by random deployment strategy; task scheduling mainly on how to migrate a specific task to the most appropriate node to implement. Real-time task exist precedence, mutual exclusion and preemption, whose delay problem not well resolved; Wireless Sensor Networks are generally applied to multi-path fading channel environment. Data transmission errors are mostly unexpected, which becomes difficult to make reliable communication. The restoration of loss data must be resolved; In high-speed wireless communication systems, due to environmental factors delayed waves interfere with the direct wave and cause intersymbol interference, which causes significant degradation of the network performance. There are practical difficulties associated with operating this equalization with high-speed, compact and low-cost hardware. We therefore look for other solution. Aimed at above problems, we research node deployment strategy, task scheduling, reliability code algorithms, orthogonal frequency division multiplexing, replica substitution algorithm for wireless video grid based on existing technologies and methods. The following are main innovations of dissertation.1. We present a new star deployment strategy for large-scale wireless sensor networks aiming at random deployment which exists issue for blind area and by chance, and that determinate deployment have inefficient. Based on star deployment strategy we analyze the connectivity probability of the global and local for networks. Then by the simulation we analyze performance of the model. Secondly, we present a new co-location algorithm based on deployment model. Feasibility of the algorithm is proved by theoretical analysis.2. We present task scheduling algorithm for offline and dynamic for Wireless Sensor Networks, whose goal is all the tasks can be executed before the task was canceled. First we study the characteristic to periodic task and task based on event-driven. Secondly, the feasibility of the algorithm is proved in theory, by giving a example explained the implementation process of the algorithm and analyzed the performance of the algorithm.3. In this paper we present a HydHOVER channel coding algorithm to guarantee reliable data transmission, which is applied to wireless sensor networks. The algorithm can recover original data when three data frame are lost. Secondly we expound the principle of HydHOVER coding and decoding in detailed. By an example we demonstrate coding and decoding process, and test the performance of the algorithm.4. We build a simulation model based on OFDM for wireless sensor networks. When guard interval and pilot symbol are inserted, we analyze bit errors rate and the frame error rate of transmission data to Rayleigh fading and flat fading channel. Finally, in different carrier frequency offset, we analyze the BER and FER owe to ICI effect.5. Referencing to ideas of Optorsim, combined with characteristic of distributed VOD and summarizing some mathematics modesl for wireless video grid, we develop a prototype system which is WvgSim for wireless Video grid based on Optorsim. We present an optimization algorithm of selection and substitution replica based on collaborative cache, which is applied to WvgSim.