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991.
We address a parametric joint detection‐estimation problem for discrete signals of the form , , with an additive noise represented by independent centered complex random variables . The distributions of are assumed to be unknown, but satisfying various sets of conditions. We prove that in the case of a heavy‐tailed noise it is possible to construct asymptotically strongly consistent estimators for the unknown parameters of the signal, i.e., frequencies , their number N, and complex coefficients . For example, one of considered classes of noise is the following: are independent identically distributed random variables with and . The construction of estimators is based on detection of singularities of anti‐derivatives for Z‐transforms and on a two‐level selection procedure for special discretized versions of superlevel sets. The consistency proof relies on the convergence theory for random Fourier series.  相似文献   
992.
In this paper, autocovariance nonstationary time series is clearly defined on a family of time series. We propose three types of TVPAR (time-varying parameter auto-regressive) models: the full order TVPAR model, the time-unvarying order TVPAR model and the time-varying order TVPAR model for autocovariance nonstationary time series. Related minimum AIC (Akaike information criterion) estimations are carried out. This work was supported by the Doctoral Research Fund of the Ministry of Education, China (Grant No. 20040285008), and Grant-in-Aid for Scientific Research (B), the Ministry of Education, Science, Sports and Culture, Japan, 2005 (Grant No. 17300228)  相似文献   
993.
The precession β and the dissipation parameter α of a ferromagnetic material can be considered microscopically space dependent. Their space distribution is difficult to obtain by direct measurements. In this article we consider an inverse problem, where we aim at recovering α and β from space measurements of the magnetization. The evolution of the magnetization in micromagnetism is governed by the Landau-Lifshitz (LL) equation. We first study the sensitivity of the LL equation. We derive the existence, uniqueness and stability results for the LL equation and the corresponding sensitivity equations. On the basis of the results we analyze the inverse problem. We employ the energy method and we minimize the underlying cost functional by means of the steepest descent method. We derive a convergence result for the proposed algorithm. The presented numerical examples support the theoretical results.  相似文献   
994.
Atomic (qubit) and optical or microwave (modal) phase-estimation protocols are placed on the same footing in terms of quantum-circuit diagrams. Circuit equivalences are used to demonstrate the equivalence of protocols that achieve the Heisenberg limit by employing entangled superpositions of Fock states, such as N00N states. The key equivalences are those that disentangle a circuit so that phase information is written exclusively on a mode or modes or on a qubit. The Fock-state-superposition phase-estimation circuits are converted to use entangled coherent-state superpositions; the resulting protocols are more amenable to realization in the lab, particularly in a qubit/cavity setting at microwave frequencies.  相似文献   
995.
Comparison of adaptive filters for gas turbine performance monitoring   总被引:2,自引:0,他引:2  
Kalman filters are widely used in the turbine engine community for health monitoring purpose. This algorithm has proven its capability to track gradual deterioration with a good accuracy. On the other hand, its response to rapid deterioration is either a long delay in recognising the fault, and/or a spread of the estimated fault in several components. The main reason of this deficiency lies in the transition model of the parameters that assumes a smooth evolution of the engine’s condition. The aim of this contribution is to compare two adaptive diagnosis tools that combine a Kalman filter and a secondary system that monitors the residuals. This auxiliary component implements on one hand a covariance matching scheme and on the other hand a generalised likelihood ratio test to improve the behaviour of the diagnosis tool with respect to abrupt faults.  相似文献   
996.
We consider random arrays and the associated empirical distributions obtained by multivariate sampling from a stationary process. Under suitable conditions, one gets convergence toward a separately exchangeable array and its ergodic distribution. The result is related to the statistical problem of estimating the representing function of an exchangeable array. The latter problem is well-posed only for shell-measurable arrays, where the grid processes based on finite sub-arrays form consistent estimates with respect to a suitable norm. In general, the required consistency holds only in the distributional sense for the generated arrays.  相似文献   
997.
对《中国惯性技术学报》1 996~ 2 0 0 0年内刊发的论文进行了分类统计 ,从刊载的论文量、论文内容和论文作者的地域分布以及作者署名情况、文献引用等几个方面进行了分析 ,简要勾画出了我国惯性技术领域科技论文产出力的分布和影响力的概貌 ,最后进行综合评价并提出了几点建议。  相似文献   
998.
In this study, two new approaches for due date assignment in job shops are evaluated. Proposed approaches use statistical prediction techniques for dynamic prediction of job flowtimes in a job shop environment as the job arrives to the shop floor. Primary objective of this research is to compare the performance of the proposed due date assignment model (PDDAM) with several conventional due date assignment models (CDDAM). For this purpose, simulation models are developed and comparisons of the PDDAM and CDDAM are made in terms of the mean absolute percent error (MAPE), mean percent error (MPE) and mean tardiness (MT). Simulation experiments showed that for many test conditions, PDDAM dominates CDDAM. Therefore, case by case findings are summarized in the paper.  相似文献   
999.
The minimum covariance determinant (MCD) scatter estimator is a highly robust estimator for the dispersion matrix of a multivariate, elliptically symmetric distribution. It is relatively fast to compute and intuitively appealing. In this note we derive its influence function and compute the asymptotic variances of its elements. A comparison with the one step reweighted MCD and with S-estimators is made. Also finite-sample results are reported.  相似文献   
1000.
知情交易者和不知情交易者的策略互动   总被引:1,自引:0,他引:1  
本文利用EEOW模型结合高频交易数据,对中国股票市场上知情交易者和不知情交易者的交易策略互动进行了实证研究.研究发现:在中国股票市场上,不知情交易者的交易行为对知情交易者没有影响,但是知情交易者的交易行为却对不知情交易者有显著的影响.当预期到市场上有众多知情交易者时,不知情交易者就减少交易以降低与知情交易者发生交易的概率.这一点与传统模型中的"噪声"交易者假设是不一致的.本文的结论对于今后构建更加贴近实际情况的交易策略模型有很好的指导意义.  相似文献   
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