Using uniform circular array, a passive localisation algorithm is presented for the scenarios where both far-field and near-field narrow-band signals may exist synchronously. The differencing matrix and the orthogonal projection matrix of the signal subspace are built to classify the mixed signals and to estimate the 2D direction-of-arrivals (DOAs) of the near-field signals (NFSs). Then, the covariance matrix of signals is decomposed to obtain the noise subspace. Meanwhile, 1D multiple signal classification (MUSIC) is used to estimate the ranges of the NFSs and 2D MUSIC is used to estimate the DOAs of far-field signals (FFSs). Compared with two-stage MUSIC (TSMUSIC), the proposed algorithm can provide higher resolution for the DOAs so that the signals can be separated. In addition, compared with TSMUSIC and four-order cumulant MUSIC, the proposed algorithm has higher accuracy for localisation of both FFSs and NFSs. Simulation results are carried out to verify the performance of the proposed algorithm.
The requirements of grand challenge problems and the deployment of gigabit networks makes the network computing framework an attractive and cost effective computing environment with which t o interconnect geographically distributed processing and storage resources. Our project, Virtual Distributed Computing Environment ( V D C E ) , provides a problem-solving environment f o r high-performance distributed computing over wide area networks. V D C E delivers well-defined library functions that relieve end-users of tedious task implementations and also support reusability. I n this paper we present the conceptual design of V D C E software architecture, which is defined in three modules: a) the Application Editor, a user-friendly application development environment that generates the Application Flow Graph ( A F G ) of an application; b) the A pplication Scheduler, which provides an efficient task-toresource mapping of AFG; and c ) the V D C E Runtime System, which is responsible for running and managing application execution and monitoring the VDCE resources. I n t r o d u c t i o nGrand challenge problems have computational and storage resource requirements that are beyond the capacities of a single computing environment. Addition-*This research is supported by Rome Lab contract number F30602-95-C-0104. ally, emerging network technologies such as fiber-optic transmission facilities and the Asynchronous Transfer Mode (ATM) enable data to be transferred at the rate of a gigabit per second (Gbps). A high-speed network of geographically distributed heterogeneous resources represents a cost-effective, network-based computing environment for solving large-scale problems addressed by grand and national challenges. New software development models and problem solving environments are being developed to utilize efficiently the network computing environment.The software development process of parallel and distributed applications can be broadly described in terms of three phases: a) application development and specification, b) application scheduling and resource configuration, and c) application execution and runtime. Most of the related work so far has focused only on one or two of these phases; only a very few projects have completely addressed all phases of software development.The first phase, i.e, parallel and distributed application development and specification phase, overwhelms most users because of the difficulty of expressing communication and synchronization among computations 131. Some text-based parallel programming environments support the data-parallel paradigm, which requires advanced compilation techniques and compilers. Most of the other environments require explicit insertion of communication and synchronization primitives within the programs, which makes programs difficult to understand. Over the last few years a number 40
Most of the existing non-contact flame temperature measurement methods rely on the ideal thermal-optical excitation model, which has a great influence on temperature measurement accuracy. Therefore, based on element doping and energy spectrum analysis, this study proposes a novel twodimensional (2-D) estimation method for flame temperature and emissivity distribution. The element doping method and laser-induced breakdown spectroscopy (LIBS) are introduced into the temperature field test. The external doped element whose spectral radiation characteristics are easy to be analyzed, is regarded as the measured particles to describe the flame temperature distribution from the side. And LIBS is used to analyze and select the doped element, and further determine the effective working wavelength of the optical camera. Besides, the relationship between spectral radiance and emissivity (L -ε) of doped samples is obtained by the emissivity calibration experiment. Then, the 2-D temperature and emissivity distributions can be estimated. Infrared thermograph is used to verify the accuracy of temperature measurement, the measurement error between calculated and standard values is not more than 5%. The experimental results of the oxygen-ethanol combustion flame show that this method can be well applied to the similar temperature measurement.INDEX TERMS Temperature measurement, Spectral emissivity, Element doping, Spectral analysis.
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