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101.
102.
自适应相干噪声衰减技术 总被引:6,自引:0,他引:6
去除噪声是必需的地震数据处理过程。由于地表条件和地震波激发、传播以及接收条件等诸多方面的原因,时常引起地震记录上出现各种相干干扰波。本文主要针对地震数据处理中地震剖面上存在的各种相干噪声,提出了时问一空间域自适应相干噪声衰减技术,以进行信噪分离。这种方法把噪声在整个处理平面上的视速度近似看作常量(正值或负值),可以有效地消除地震剖面上的线性噪声、面波以及多次波等,并且对信号的保真度高。本文方法是复杂地区低信噪比地震数据处理的一种理想的噪声去除方法,具有运算速度快、压制噪声效果好等优点。 相似文献
103.
机载红外搜索跟踪系统被动定位滤波算法研究 总被引:1,自引:1,他引:0
首先用扩展卡尔曼滤波算法构建了机载红外搜索跟踪系统被动定位滤波模型.然后针对该滤波算法要求先验的噪声统计及存在系统观测模型线性化误差影响滤波精度的特点.利用虚拟噪声技术,提出了适合于红外搜索跟踪系统被动定位的自适应扩展卡尔曼滤波算法。该算法实时地估计了虚拟噪声的统计特性,减小了线性化误差,提高了非线性滤波的精度。仿真结果表明,在完全相同的初始条件下,自适应扩展卡尔曼滤波对目标距离和速度的估计结果明显优于扩展卡尔曼滤波,此算法具有很高的工程应用价值。 相似文献
104.
Patrick Musonda 《Computational statistics & data analysis》2008,52(4):1942-1957
Second-order expressions for the asymptotic bias and variance of the log relative incidence estimator are derived for the self-controlled case series model in a simplified scenario. The dependence of the bias and variance on factors such as the relative incidence and ratio of risk to observation period are studied. Small-sample performance of the estimator in realistic scenarios is investigated using simulations. It is found that, in scenarios likely to arise in practice, asymptotic methods are valid for numbers of cases in excess of 20-50 depending on the ratio of the risk period to the observation period and on the relative incidence. The application of Monte Carlo methods to self-controlled case series analyses is also discussed. 相似文献
105.
Min-Max MPC (MMMPC) controllers [P.J. Campo, M. Morari, Robust model predictive control, in: Proc. American Control Conference, June 10–12, 1987, pp. 1021–1026] suffer from a great computational burden which limits their applicability in the industry. Sometimes upper bounds of the worst possible case of a performance index have been used to reduce the computational burden. This paper proposes a computationally efficient MMMPC control strategy in which the worst case cost is approximated by an upper bound based on a diagonalization scheme. The upper bound can be computed with O(n3) operations and using only simple matrix operations. This implies that the algorithm can be coded easily even in non-mathematical oriented programming languages such as those found in industrial embedded control hardware. A simulation example is given in the paper. 相似文献
106.
本文自行研制了一台Fabry—Perot干涉仪及其用于探测超声信号的测试系统。利用该系统对非光学表面的铝板和铜板实现了nm级窄脉冲激光超声信号的非接触式检测,其信噪比足以满足进一步信号处理要求。 相似文献
107.
激光与DNA作用系统的随机共振研究 总被引:6,自引:2,他引:4
建立了激光与DNA分子系统相互作用的Fokker-Planck方程,通过对该方程的数值研究,发现在绝热近似下,系统发生随机共振,噪声强度,激光振幅和频率协同作用共同制约着生物系统的演化过程,噪声强度在生物系统遗传变异过程中可能起重要作用。 相似文献
108.
Takumi Haruna 《Corrosion Science》2003,45(9):2093-2104
We have investigated the electrochemical noise behavior of carbon steel in fully deaerated aqueous bicarbonate solutions, and discussed the optimum conditions of the noise analysis for estimating corrosion rate of the steel. Noise of the potential difference and of the short-circuit current between two identical steel coupons were successfully measured. The time-series noise patterns were transformed into frequency domain by fast Fourier transformation, and then their power spectrum densities (PSDs) at a frequency were determined to be compared with the corrosion rate. The PSDs of the potential and of the current varied with changing environmental factors of bicarbonate concentration, pH, and immersion time. The factors also controlled the corrosion rate of the steel. The PSDs were associated with the corrosion rate, and then it was found that the PSDs of the potential and of the current showed linear correlation with the corrosion rate in log-log scale. There was also linear relationship between the corrosion rate and a spectral noise resistance obtained from the PSDs of the potential and the current. The linearities of the three correlations were better at a lower analyzed frequency. Furthermore, the PSDs of the current and the noise resistance indicated more linear correlation with the corrosion rate than that of the potential. As the simplicity of the measurement system is additionally considered, it is concluded that the PSD of the current noise at an analyzed frequency of 3 mHz is the optimum conditions for estimating the corrosion rate from 10−2 to 100 A m−2 in this study. 相似文献
109.
Evaluation of rainfall networks using entropy: II. Application 总被引:2,自引:0,他引:2
This paper, the second in the series, applies the entropy approach to space and time evaluation of rainfall networks in Louisiana. The evaluation is made for five sampling intervals: daily, 2-day, weekly, monthly, and yearly, and for two separate seasons. In each case, the best combination of raingages is suggested and the lines of equal information (isoinformation contours) are constructed showing the areas of greater or less information transfer. The isoinformation lines are especially suitable in decisions concerning the expansion of the existing network or deleting the unnecessary raingages. 相似文献
110.
Abstract. A procedure for evaluating optimal linear estimates of missing values in the minimum dispersion sense is proposed for stationary symmetric stable processes. Analytical expressions for the estimates are obtained for the autoregressive moving-average process and it is shown that the finite variance setting results are special cases. Cases of one and more than one missing value are considered. 相似文献