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991.
The point and interval estimations for the unknown parameters of an exponentiated half-logistic distribution based on adaptive type II progressive censoring are obtained in this article. At the beginning, the maximum likelihood estimators are derived. Afterward, the observed and expected Fisher’s information matrix are obtained to construct the asymptotic confidence intervals. Meanwhile, the percentile bootstrap method and the bootstrap-t method are put forward for the establishment of confidence intervals. With respect to Bayesian estimation, the Lindley method is used under three different loss functions. The importance sampling method is also applied to calculate Bayesian estimates and construct corresponding highest posterior density (HPD) credible intervals. Finally, numerous simulation studies are conducted on the basis of Markov Chain Monte Carlo (MCMC) samples to contrast the performance of the estimations, and an authentic data set is analyzed for exemplifying intention. 相似文献
992.
993.
The life analysis of engine components needs to take into account the residual stress relaxation induced by cyclic service loads. The paper recalls a new class of constitutive equations for cyclic viscoplasticity, using a series of kinematic hardening models with thresholds. The equations are introduced within a recently enlarged thermodynamic framework. Some attention is focused to the relations with multisurface approaches and to a specific determination procedure of the model parameters. The new model is applied to the calculation of the near surface residual stress relaxation after shot peening, when the structure is submitted to cyclic service loads. The simulated stabilized residual stresses are in good accordance with experimental results obtained on an N18 disk alloy at 650°C. In comparison, the classical model without threshold predicts the complete vanishing of the residual stresses, which is not satisfactory. 相似文献
994.
利用基于Marangoni界面效应对化学抛光去除函数的理论及实验进行研究,提出采用湿法化学抛光(刻蚀)方法为大口径高精度光学元件的加工提供新的解决途径。介绍了Marangoni界面效应及其验证实验,运用WYKO轮廓仪对熔石英基片局域刻蚀前后的粗糙度进行检测,结果表明,粗糙度基本无变化,刻蚀前后粗糙度分别为0.72 nm和0.71 nm。基于Preston假设, 建立了数控化学抛光理论模型,运用WYKO干涉仪观察实验现象可知,化学抛光刻蚀曲线基本上成平底陡峭的去除函数曲线,小磨头抛光是倒置的仿高斯函数曲线。 相似文献
995.
996.
考虑随机系数自回归模型Yt =Φtyt-1+ ut,其中 Φt为随机系数,ut为随机误差。在允许Φt与ut相依以及Eut无穷的条件下,构造了误差方差的自加权估计,并证明了该估计的渐近正态性。最后通过数值模拟,说明
自加权估计的稳健和有效性。 相似文献
997.
Fahimeh Salari Sehdaran Mohammad H. Zandi Alireza Bahrampour 《Physics letters. A》2019,383(35):126006
This work aims to compare results of dissipating and pure dephasing single-qubit probes in characterizing the cutoff frequency of a harmonic reservoir Ohmic spectral density. In particular, we proved that a dissipating single-qubit improves the estimation precision of the cutoff frequency estimator. The information backflow and outflow of the dissipating and the dephasing single-qubit are compared. The relation between the quantum Fisher information and the information outflow and backflow of the probe is obtained. The results show that difference between the values of information outflow and backflow of a dissipating single-qubit is larger than a dephasing single-qubit. So, a single-qubit probe extracts more information from an Ohmic reservoir by increasing the difference between the values of information outflow and backflow of the probe. 相似文献
998.
A Gross-Pitaevskii (GP) equation with a parabola external potential is considered, and is transformed into a standard nonlinear Schrödinger (NLS) equation. By using the homogeneous balance principle and F-expansion method, we study non-autonomous wave solutions of the GP equation with a parabola external potential. In particular, based on the similarity transformation, several families of non-autonomous wave solutions of the GP equation are presented with snaking behaviors and different amplitude surfaces. These obtained bright-dark soliton solutions can give some potential applications in Bose-Einstein condensates. 相似文献
999.
1000.
有效估计阵形是提高机动条件下拖线阵声呐探测性能的关键,流体力学类阵形估计方法稳定性和可靠性欠佳,导致其难以应用于工程实际,该文针对此问题提出一种基于拖线阵运动特性的阵形估计方法。利用稳态振荡响应公式计算拖船回转机动时拖线阵稳态阵形特性,将转向机动过程中阵上各点运动状态划分为若干阶段,进而依据偏微分方程特征线理论计算各阶段的分界时刻,探究阵上相邻两点的沿阵切线方向差变化规律,最后通过计算当前阵上各点的沿阵方向实现阵形估计。计算机仿真和海上实验数据验证表明算法可行且有效,与传统的流体力学类阵形估计方法相比具有更高的稳定性和更好的工程应用前景。 相似文献