56 research outputs found

    Geometric Buildup Algorithms for Sensor Network Localization

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    We present a geometric buildup algorithm for solving the sensor network localization problem with either accurate or noisy distance data. The algorithm determines the locations of the sensors, one at a time, by using the distances between the determined sensors and the undetermined ones. Each time, only a small system of distance equations needs to be solved and therefore, in an ideal case when the required distances are available for every sensor to be determined, the computation can be completed in n steps if n sensors are to be determined. An algorithm with two buildup phases is also implemented to handle not only noisy but also sparse distance data with for example only a few distant anchors. We show our test results and compare them with other approaches

    Research and Implementation of Distributed Database HBase Monitoring System

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    With the arrival of large data age, distributed database HBase becomes an important tool for storing data in massive data age. The normal operation of HBase database is an important guarantee to ensure the security of data storage. Therefore designing a reasonable HBase monitoring system is of great significance in practice. In this article, we introduce the solution, which contains the performance monitoring and fault alarm function module, to meet a certain operator’s demand of HBase monitoring database in their actual production projects. We designed a monitoring system which consists of a flexible and extensible monitoring agent, a monitoring server based on SSM architecture, and a concise monitoring display layer. Moreover, in order to deal with the problem that pages renders too slow in the actual operation process, we present a solution: reducing the SQL query. It has been proved that reducing SQL query can effectively improve system performance and user experience. The system work well in monitoring the status of HBase database, flexibly extending the monitoring index, and issuing a warning when a fault occurs, so that it is able to improve the working efficiency of the administrator, and ensure the smooth operation of the project

    Research and Implementation of Distributed Database HBase Monitoring System

    No full text
    With the arrival of large data age, distributed database HBase becomes an important tool for storing data in massive data age. The normal operation of HBase database is an important guarantee to ensure the security of data storage. Therefore designing a reasonable HBase monitoring system is of great significance in practice. In this article, we introduce the solution, which contains the performance monitoring and fault alarm function module, to meet a certain operator’s demand of HBase monitoring database in their actual production projects. We designed a monitoring system which consists of a flexible and extensible monitoring agent, a monitoring server based on SSM architecture, and a concise monitoring display layer. Moreover, in order to deal with the problem that pages renders too slow in the actual operation process, we present a solution: reducing the SQL query. It has been proved that reducing SQL query can effectively improve system performance and user experience. The system work well in monitoring the status of HBase database, flexibly extending the monitoring index, and issuing a warning when a fault occurs, so that it is able to improve the working efficiency of the administrator, and ensure the smooth operation of the project

    Numerical Simulation Three-Dimensional Nonlinear Seepage in a Pumped-Storage Power Station: Case Study

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    Due to high water pressure in the concrete reinforced hydraulic tunnels, surrounding rocks are confronted with nonlinear seepage problem in the pumped storage power station. In this study, to conduct nonlinear seepage numerical simulation, a nonlinear seepage numerical model combining the Forchheimer nonlinear flow theory, the discrete variational inequality formulation of Signorini’s type and an adaptive penalized Heaviside function is established. This numerical seepage model is employed to the seepage analysis of the hydraulic tunnel surrounding rocks in the Yangjiang pumped-storage power station, which is the highest water pressure tunnel under construction in China. Moreover, the permeability of the surrounding rocks under high water pressure is determined by high pressure packer test and its approximate analytical model. It is shown that the flow in the surrounding rocks is particularly prone to become nonlinear as a result of the high flow velocities and hydraulic gradients in the nearby of the seepage-control measures and the high permeability fault. The nonlinear flow theory generates smaller flow rate than the Darcy flow theory. With the increase of nonlinear flow, this observation would become more remarkable

    A Metal-Free Facile Construction of C(sp3) –CF3 Bond: Trifluoromethylation of Hydrazones with Togni’s Reagent under Mild Conditions

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    A metal-free trifluoromethylation of hydrazones with Togni’s reagent under mild conditions was developed. Various functional groups including ester, methoxy, dimethoxy, nitro, halogen and heterocyclic compounds were tolerated. This simple and green strategy provides a practical tool to construct C(sp3) –CF3 bond
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