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Because measurement uncertainty is an important parameter to evaluate the reliability of measurement results, it is essential to present reliable methods to evaluate the measurement uncertainty especially in precise optical measurement.Though Monte-Carlo (MC) method has been applied to estimate the measurement uncertainty in recent years, this method, however, has some shortcomings such as low convergence and unstable results. Therefore its' application is limited. To evaluate the measurement uncertainty in a fast and robust way, Quasi Monte-Carlo (QMC) method is adopted in this paper. In the estimating process, more homogeneous random numbers (quasi random numbers) are generated based on Halton's sequence, and then these random numbers are transformed into the desired distribution randomnumbers. An experiment of cylinder measurement is given. The results show that the Quasi Monte-Carlo method has higher convergence rate and more stable evaluation results than that of Monte-Carlo method. Therefore, the quasi Monte-Carlo method can be applied efficiently to evaluate the measurement uncertainty.

The optimization design of micro‐structure and composition is an important strategy to obtain high‐performance metal‐based electromagnetic (EM) wave absorption materials. In this work, ZnO/FeNi composites derived from ZnFeNi layered double hydroxides are prepared by a one‐step hydrothermal method and subsequent pyrolysis process, and can be employed as an effective alternative for high‐performance EM wave absorber. A series of ZnO/FeNi composites with different structures are obtained by varying the molar ratios of Zn2+/Fe3+/Ni2+, and the ZnO/FeNi composites with a Zn2+/Fe3+/Ni2+ molar ratio of 6:1:3 show a hierarchical flower‐like structure. Owing to the strong synergistic loss mechanism of dielectric‐magnetic components and favorable structural features, this hierarchical flower‐like ZnO/FeNi sample supplies the optimal EM wave absorption performance with the highest reflection loss of −52.08 dB and the widest effective absorption bandwidth of 6.56 GHz. The EM simulation further demonstrates that impedance matching plays a determining role in EM wave absorption performance. This work provides a new way for the fabrication of a high‐performance metal‐based EM wave absorber.

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Coordinate measuring machine (CMM) plays a more and more important role in the flatness evaluation. The pre-processing for eliminating error data is an important process to improve the quality of flatness evaluation. So, flatness uncertainty estimation becomes a key problem. To solve the problem, a flatness uncertainty estimation method based on data elimination is presented. Firstly, a method for excluding the error data based on statistical theory is expatiated with the consideration of probability theory and mathematical statistics. Secondly, details of calculating flatness uncertainty based on least-square method are analyzed. Then the measured 3-dimensional data are processed so as to put the excluding method into use. So the error data can be deleted and the flatness uncertainty can be decreased and can achieve a good evaluation quality. Finally, an example is given and the result shows that the method proposed in this paper is feasible.