截尾数据下一类半参数回归模型的估计

讨论了一类半参数回归模型y =x′β+g(t′α) +e .假定y被随机变量T右侧截尾 ,T与y独立 ,T～G。在G已知和未知两种情况下 ,构造了α、β和g(·) 的强相合估计     

逐步增加Ⅱ型截尾下Weibull分布的Bayes估计

基于逐步增加的Ⅱ型截尾,讨论了Weibull分布的Bayes估计。在平方损失和LINEX损失下,利用LindelyBayes近似算法得到了形状参数,尺度参数,失效率函数以及可靠度函数的极大似然估计和Bayes估计。最后运用Monte Carlo方法对各估计结果的RMSE,进行了模拟比较。表明了LINEX损失下的结果更有效。     

基于部分岭估计的Zernike模式法人眼波前像差重建

为了提高自适应光学系统中人眼波前像差的重建精度,进而提高自适应光学图像中的点扩散函数重建精度,提出了一种基于部分岭估计的Zernike模式前重建算法。首先,基于Zernike模式波前重建模型,分析了常用的模式系数求解方法;其次,在最小均方误差意义下,将部分岭估计的概念引入到自适应光学系统的波前重建算法中,通过确定最优岭估计参数来改善最小二乘估计的奇异性,从而抑制波前探测中测量误差的进一步被放大;最后,讨论了在波前斜率误差的影响下由两种算法所产生的误差大小。仿真实验结果表明：在波前重建算法中引入部分岭估计可有效减小模式系数的均方误差,相对于奇异值分解法减小了8%~10%,在波前探测测量误差增大的情况下,部分岭估计的波前重建精度要高于最小二乘估计法,有利于自适应光学后期中基于波前探测的图像复原研究。     

删失数据下一类回归模型的参数估计

考虑一类回归模型,在右删失数据下构造了参数的最小二乘估计和加权最小二乘估计,证明了估计量具有渐近正态性。模拟结果表明加权最小二乘估计比最小二乘估计有优良的性质。     

非标准人体静电模型实验数据的理论转换

目的　静电敏感度数据的处理 .方法　从旺希贝尔模型出发 ,利用理论推导 ,处理非标准人体静电模型的实验数据 .结果　得到 RC放电模型之间的转换公式 .结论　便于不同静电敏感度数据的比较分类     

Estimation and Validation of Semiparametric Dynamic Nonlinear Models

An approach for measurement-based modeling of nonlinear devices is proposed. The method that is commonly used for linear time-invariant systems, namely, parametric modeling and nonparametric verification, is hereby extended to a class of nonlinear systems. The applicability of the method is illustrated on the baseband modeling of a radio-frequency amplifier over a wide power and frequency range.     

The Use of Acoustic Emission for Estimation of Bearing Defect Size

Vibration monitoring of rolling element bearings is possibly the most established diagnostic technique for rotating machinery. The application of Acoustic Emission (AE) for bearing diagnosis is gaining ground as a complementary diagnostic tool, however, limitations in the successful application of the AE technique have been partly due to the difficulty in processing, interpreting and classifying the acquired data. Furthermore, the extent of bearing damage has eluded the AE diagnostician. The investigation reported in this paper was centered on the application of the Acoustic Emission technique for identifying the size of a defect on a radially loaded bearing. An experimental test-rig was designed such that defects of varying sizes could be seeded onto the outer race of a test bearing. It was concluded that AE can provide an indication of the defect size, thus allowing the user to monitor the rate of degradation on the bearing. This article was originally published as “The Use of Acoustic Emission for Estimation of Bearing Defect Size” in Essential Technologies for Successful Prognostics, Proceedings of the 59th Meeting of the Society for Machinery Failure Prevention Technology, Society for Machinery Failure Prevention Technology, 2005, pp. 583–591, and is reprinted with permission.     

Development and Validation of HPTLC Method for Estimation of Tacrolimus in Formulations

A new, simple, and rapid high-performance thin-layer chromatographic method with a derivatization procedure was developed and validated for quantitative determination of tacrolimus. Tacrolimus was chromatographed on silica gel 60 F₂₅₄ TLC plate using toluene–acetonitrile–glacial acetic acid (6:4:0.1, by volume) as mobile phase. Tacrolimus was visualized using a derivatization reagent containing anisaldehyde–sulfuric acid in absolute alcohol and quantified by densitometric analysis in the reflectance mode at 675 nm. The method was found to give compact spots for the drug (R_f?=?0.40?±?0.03). The linear regression analysis data for the calibration plots showed good linear relationship with r²?=?.9989 in the concentration range 100–800 ng/spot. The method was validated for precision, recovery, repeatability, and robustness as per the International Conference on Harmonization guidelines. The minimum detectable amount was found to be 28.90 ng, whereas the limit of quantitation was found to be 97.04 ng. Statistical analysis of the data showed that the method is precise, accurate, reproducible, and selective for the analysis of tacrolimus. The method was successfully employed for the estimation of equilibrium solubility and quantification of tacrolimus as a bulk drug and in commercially available capsules and in-house developed self-microemulsifying formulations.     

Field Failure Data: an Alternative Proposal for Reliability Estimation

Product reliability is a very important issue for the competitive strategy of industries. In order to estimate a product's reliability, parametric inferential methods are required to evaluate survival test data, which happens to be a fairly expensive data source. Such costly information usually imposes additional compromises in the product development and new challenges to be overcome throughout the product's life cycle. However, manufacturers also keep field failure data for warranty and maintenance purposes, which can be a low‐cost data source for reliability estimation. Field‐failure data are very difficult to evaluate using parametric inferential methods due to their small and highly censored samples, quite often representing mixed modes of failure. In this paper a method for reliability estimation using field failure data is proposed. The proposal is based on the use of non‐parametric inferential methods, associated with resampling techniques to derive confidence intervals for the reliability estimates. Test results show the adequacy of the proposed method to calculate reliability estimates and their confidence interval for different populations, including cases with highly right‐censored failure data. The method is shown to be particularly useful when the sampling distribution is not known, which happens to be the case in a large number of practical reliability evaluations. Copyright © 2006 John Wiley & Sons, Ltd.     

NIST/TRC SOURCE Data Archival System: The Next-Generation Data Model for Storage of Thermophysical Properties

A new data model for storage of experimental thermophysical and thermochemical property data was developed and implemented for the NIST/TRC SOURCE data archival system. Substantial improvements in data quality, as well as system usability and extendability, are achieved. Substance identification based on chemical structures was implemented. Availability of stored chemical structures will facilitate the use of property estimation methods to supplement the experimental information.     

硬件开发工作量评估模型的研究与应用

收集了信息技术项目管理中硬件电路板开发工作量历史数据,采用统计回归分析和最小二乘法拟合开发工作量趋势线;构建了硬件电路板开发工作量评估模型;使用方差分析和实际数据校验,验证了硬件电路板开发工作量评估模型的有效性,计算得到该模型的预测工作量与实际工作量相差约7.2%.给出硬件电路板开发工作量评估模型预测区间计算方法,使HEM-BD的可靠性得到进一步提高.     

人体头部力阻抗数据

报导了在444位年龄范围很宽的受试对象的痈部位置的力阻测量结果，取得频率由100Hz到10000Hz的数值曲线，揭示了共振频率对年龄的依赖关系，并导出其对应的统计的数学表达式，实验结果与国外有关文献作了对比。     

Screening for Chemicals in Paper and Board Packaging for Food Use: Chemometric Approach and Estimation of Migration

An analytical survey of 20 paper and board (P&B) materials intended for food use was carried out with the aim to identify chemicals with a potential to migrate into foods. Representative materials covering a range of uses (primary and secondary packaging and article for take away foods) were obtained from distributors. A screening approach was applied by means of solvent extraction with subsequent analysis by gas chromatography/mass spectrometry. A large number of analytes were detected, and a chemometric approach was used to explore the data. Principal component analysis was used to identify and select some compounds as markers for sample classification. In the corrugated and printed packaging, it is worth emphasizing the presence of residual solvents, probably coming from printing inks, as well as hydrocarbons and aromatic compounds, mainly toluene and plasticizers linked also to the recycled pulp content such as diisobutyl phthalate or diisopropylnaphthalenes, whereas in the plastic‐laminated samples, triacetin was identified as the prevailing compound. A literature search for safety data or legislative restrictions of the identified substances was performed. Additionally, the semi‐quantification of the compounds in the packaging allowed a worst case estimation of food contamination by means of the infinite total migration model; occasionally, migration estimations overcame the specific migration limits. The chosen analytical methods coupled with a chemometric approach proved to be an effective way to describe the data; it may be concluded that only the simultaneous consideration of several chemicals with a multivariate approach allowed the investigated packaging materials to be distinguished. Copyright © 2014 John Wiley & Sons, Ltd.