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一种带乘性噪声的半定松弛优化TOA定位算法 被引量:5
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作者 潘思伟 骆吉安 彭冬亮 《杭州电子科技大学学报(自然科学版)》 2018年第3期65-69,共5页
在定位方法的实际应用中,噪声信号往往含有复杂的乘性噪声信号。在信噪比低或者初始值选取不恰当的情况下,传统的ML估计算法的结果易发散。为此,提出一种结合ML估计的半定松弛优化算法。首先将位置估计问题进行重构,使之转化为一个基于M... 在定位方法的实际应用中,噪声信号往往含有复杂的乘性噪声信号。在信噪比低或者初始值选取不恰当的情况下,传统的ML估计算法的结果易发散。为此,提出一种结合ML估计的半定松弛优化算法。首先将位置估计问题进行重构,使之转化为一个基于ML算法的优化问题,再对优化问题进行半定松弛求出最优解,从而得到目标的位置估计。通过多基站到达时间定位仿真实验验证了算法的有效性。 展开更多
关键词 半定松弛 乘性噪声 ML估计
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Variation in the temperature field of rocks overlying a high-temperature cavity during underground coal gasification 被引量:7
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作者 luo ji'an Wang Lianguo +2 位作者 Tang Furong He Yan Zheng Lin 《Mining Science and Technology》 EI CAS 2011年第5期709-713,共5页
High temperature affects rocks in a way that changes the physical and mechanical properties of them. The temperature field in rock overlying a high temperature zone has been estimated using experimental research on th... High temperature affects rocks in a way that changes the physical and mechanical properties of them. The temperature field in rock overlying a high temperature zone has been estimated using experimental research on thermal conductivity of the overlying strata. Numerical analysis software was used to esti- mate rock thermal conductivity at different temperatures. These estimates were then used with COMSOL Multiphysics to perform a numerical analysis with the heat conduction model. The results show that rock thermal conductivity decreases as the temperature increases and that various lithologies show similar behavior. The thermal conductivity of each rock type differs from the others at a given temperature. Exact values for the temperature distribution in the overlying strata during the process of underground coal gasification are obtained from the numerical simulation. The temperature in the rock changes with the height and direction from the gasifier. Temperature gradients vary for different types of rock. This result provides an important reference for further study of the strength of overlying strata subject to the process of underground coal gasification. 展开更多
关键词 StratumThermal conductivityTemperatureSimulation
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