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1.
温度步进应力加速寿命试验研究 总被引:7,自引:1,他引:7
提出了一种温度步进威力加速寿命试验的方法,并分别基于阿伦尼斯模型、基本GM(1,1)模型、残差修正GM(1,1)模型对温度步进应力条件下特征寿命的点估计进行了讨论,最后用3种不同的方法对给出的实例进行了求解,说明了该方法在工程应用上的可行性和有效性。 相似文献
2.
土壤碱化的实测光谱响应特征 总被引:5,自引:0,他引:5
通过实地定点土壤取样和光谱测量,研究了实测光谱反射率与土壤PH值之间的关系.分别采用反射率Reflectance、一阶导数FDR、倒数之对数log(1/R)和波段深度BD四种光谱指标建立对PH值的多元线性回归预测模型,并且利用验证样本集对回归模型进行了检验.结果表明:野外实测反射光谱与PH值呈良好的正相关关系,建模精度... 相似文献
3.
《Reliability, IEEE Transactions on》2005,54(3):530-540
Based on a generalized cumulative damage approach with a stochastic process describing initial damage for a material specimen, a broad class of statistical models for material strength is developed. Plausible choices of stochastic processes for the initial damage include Brownian motion, geometric Brownian motion, and the gamma process; and additive & multiplicative cumulative damage functions are considered. The resulting general statistical model gives an accelerated test form of the inverse Gaussian distribution, special cases of which include some existing models in addition to several new models. Model parameterizations & estimation by maximum likelihood from accelerated test data are discussed, and the applicability of the general model is illustrated for three sets of strength data. The proposed models are compared with the power-law Weibull model, and the inverse Gaussian generalized linear models. 相似文献
4.
Wide-band dynamic modeling of power amplifiers using radial-basis function neural networks 总被引:3,自引:0,他引:3
A radial-basis function neural network (RBFNN) has been used for modeling the dynamic nonlinear behavior of an RF power amplifier for third generation. In the model, the signal's envelope is used. The model requires less training than a model using IQ data. Sampled input and output signals were used for identification and validation. Noise-like signals with bandwidths of 4 and 20 MHz were used. The RBFNN is compared to a parallel Hammerstein (PH) model. The two model types have similar performance when no memory is used. For the 4-MHz signal, the RBFNN has better in-band performance, whereas the PH is better out-of-band, when memory is used. For the 20-MHz signal, the models have similar performance in- and out-of-band. Used as a digital-predistortion algorithm, the best RBFNN with memory suppressed the lower (upper) adjacent channel power 7 dB (4 dB) compared to a memoryless nonlinear predistorter and 11 dB (13 dB) compared to the case of no predistortion for the same output power for a 4-MHz-wide signal. 相似文献
5.
《Vehicular Technology, IEEE Transactions on》1978,27(4):182-189
The correlation in mean received power from four non-cosited 900 MHz sources is studied as a function of angle of arrival difference (AAD) at the mobile. Two tests are examined, one in the Washington-Baltimore area, and the other in the Chicago-Schaumburg area. Three hundred meter power averages were taken in Washington while 20 meter averages were obtained in Chicago. Weighted correlation coefficients averaging in the order of 0.7 were obtained at small AAD's. Serial correlations are also examined. A table lookup model of correlation coefficient versus AAD was obtained from the measurements. This was applied to the cellular system simulation to show differences in estimated performance with and without AAD correlation taken into account. The example given was assumed to be in an urban propagation enviroment with a 19-mile separation between co-channel users. Differences in 〈C〉/〈I〉 of 2.7 dB with omni antennas and 4.7 dB with 60-degree sector antennas are obtained at the level achievable at 90% of the locations. 相似文献
6.
This paper presents the inferences of parameters on the simple step-stress model in accelerated life testing with type-II censoring. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model are assumed. Maximum likelihood methods are used to estimate the parameters of these models. Hypothesis tests about model parameters are discussed. Confidence intervals for parameter-estimates are constructed using a pivotal quantity. The advantage of these results is that they apply to any sample size. A numerical example illustrates the inferential procedure 相似文献
7.
Extrapolating reliability from accelerated tests for technologies without field data always carries the risk that the accelerated tests do not show the mechanisms which dominate at operating conditions. In statistical terminology, such accelerated testing carries a risk of confounding. For linear models, there is theory which allows one to determine which models are confounded with others. This paper develops analogous theory for a simple kind of confounding model, evanescent processes, when kinetics is used as the basis of modeling accelerated testing. A heuristic for identifying simple evanescent processes that can give rise to disruptive alternatives (alternative models that reverse the decision which would be made based on modeling to date) is outlined. Then, we develop activity mapping, a tool for quantitatively identifying the parameter values of that evanescent process which can result in disruptive alternatives. Finally, we see how activity mapping can be used to identify experiments which help reveal such disruptive evanescent processes 相似文献
8.
《Mechatronics》2014,24(8):1001-1007
Passivity-based control (PBC) is commonly used for the stabilization of port-Hamiltonian (PH) systems. The PH framework is suitable for multi-domain systems, for example mechatronic devices or micro-electro-mechanical systems. Passivity-based control synthesis for PH systems involves solving partial differential equations, which can be cumbersome. Rather than explicitly solving these equations, in our approach the control law is parameterized and the unknown parameter vector is learned using an actor–critic reinforcement learning algorithm. The key advantages of combining learning with PBC are: (i) the complexity of the control design procedure is reduced, (ii) prior knowledge about the system, given in the form of a PH model, speeds up the learning process, (iii) physical meaning can be attributed to the learned control law. In this paper we extended the learning-based PBC method to a regulation problem and present the experimental results for a two-degree-of-freedom manipulator. We show that the learning algorithm is capable of achieving feedback regulation in the presence of model uncertainties. 相似文献
9.
In this paper, a novel queuing analytical framework is introduced to analyze the performance of the HCF controlled channel
access designed as a medium access mechanism in wireless local area networks. The queuing model defines a multi-rate medium
using adaptive modulation and coding which is a key point in wireless networks to increase effective transmission rate. Based
on a MAP (Markovian arrival process)/PH (phase type)/1 queue with vacation and time-limited service, the model considers a
limited node buffer and non-ideal channel with the automatic repeat request protocol. Using a MAP for traffic arrival process
and PH distribution for packet service process, the inclusion of the non-transmission and vacation processes makes our analysis
very general and comprehensive to support various types of practical traffic streams. To formulate the model, the powerful
matrix-geometric method is employed, and the mutual impacts of some parameters in the MAC and the PHY layers are then evaluated
to improve system performance. Finally, optimization of parameter settings to maximize throughput is discussed. 相似文献
10.
11.
In this article, we derive expressions for the asymptotic distribution of maximum likelihood estimators of model parameters in accelerated life tests (ALTs) when the model distribution is misspecified. We investigate results for two popular models, namely, the lognormal and Weibull Arrhenius-type ALT models. We propose test plan criteria based on asymptotic bias (ABias) and asymptotic mean squared error (AMSE) to derive ALT test plans. We derive 4:2:1 allocation plans that minimize either ABias/sup 2/ or AMSE. These criteria provide control over estimation bias and variance when the model distribution is misspecified. 相似文献
12.
《Components and Packaging Technologies, IEEE Transactions on》2008,31(3):634-641
13.
讨论了4种用于描述加速寿命试验中失效分布参数和环境条件之间关系的失效物理模型。针对阿伦尼斯模型,探讨了加速寿命试验中的参数估计方法,构建了参数的极大似然估计(MLE)方程组,解得加速寿命试验中失效分布参数的MLE值,进而通过转化,借助于标准正态分布表获得其寿命指标的近似值,并通过一个实例介绍了其具体应用。 相似文献
14.
Runying Dai Xiangchuan Meng Jiaqi Zhang Zhixing Cai Licheng Tan Yiwang Chen 《Advanced functional materials》2023,33(45):2305013
The buried interface has important effect on carrier extraction and nonradiative recombination of perovksite solar cells (PSCs). Herein, to inactivate the buried interfacial defects of perovskite and boost the crystallization quality of perovskite film, 3-amino-1-adamantanol (AAD) serves as a pre-buried interface modifier on nickel oxide (NiOx) surface to regulate the nucleation and crystallization process of perovskite precursor. The amino and hydroxyl groups in AAD molecule can synchronously coordinate with nickel ion (Ni3+) in NiOx and lead ion in perovskite, respectively. The dual action favors the ordered arrangement of AAD molecules between NiOx and perovskite, which not only enhances hole extraction in hole transport layer, but also provides active sites for homogeneous nucleation. Furthermore, AAD modifier blocks the unfavorable reaction between Ni3+ and perovskite, and effectively passivates the buried interfacial defects. The optimal inverted PSCs achieve a champion power conversion efficiency of 22.21% with negligible hysteresis, favorable thermal, optical, and long-term stability. Thus, this strategy of modulating perovskite nucleation and crystallization by pre-buried modifier is feasible for achieving efficient and stable inverted perovskite solar cells. 相似文献
15.
In order to verify which of the distributions and established methods of reliability model are more suitable for the analysis of the accelerated aging of LED lamp, three established methods (approximate method, analytical method and two-stage method) of reliability model are used to analyze the experimental data under the condition of the Weibull distribution and Lognormal distribution, in this paper. Ten LED lamps are selected for the accelerated aging experiment and the luminous fluxes are measured at an accelerated aging temperature. AIC information criterion is adopted in the evaluation of the models. The results show that the accuracies of the analytical method and the two-stage method are higher than that of the approximation method, with the widths of confidence intervals of unknown parameters of the reliability model being the smallest for the two-stage method. In a comparison between the two types of distributions, the accuracies are nearly identical. 相似文献
16.
Accelerated degradation analysis plays an important role in assessing reliability and making maintenance schedule for highly reliable products with long lifetime. In practical engineering, degradation data, especially measured under accelerated condition, are often compounded and contaminated by measurement errors, which makes the analysis more challenging. Therefore, a Wiener process model simultaneously incorporating temporal variability, individual variation and measurement errors is proposed to analyze the accelerated degradation test (ADT). The explicit forms of the probability distribution function (PDF) and the cumulative distribution function (CDF) are derived based on the concept of first hitting time (FHT). Then, combining with the acceleration models, the maximum likelihood estimations (MLE) of the model parameters are obtained. Finally, a comprehensive simulation study involving two examples and a practical application are given to demonstrate the necessity and efficiency of the proposed model. 相似文献
17.
Distinct morphologies of electromigration-induced voids and failures are shown for Al, Al-2%Cu, and Al-2%Cu-l% Si narrow (1–6
μm) unpassivated thin film conductors. SEM and TEM images typically show large non-fatal voids and narrow slit-like open circuit
failures for all film conditions and accelerated test conditions. Evidence for transgran-ular slit failures is shown for 1.33
μm wide conductors. A simple model for void growth is presented which accounts for the void morphologies seen. The observed
morphologies and the results of void growth modelling suggest that slit voids nucleate after other voids and rapidly produce
failure. These conclusions are discussed in terms of ‘classical’ models for electromigration failure processes and resistance
and noise power monitoring techniques. 相似文献
18.
A new model for step-stress testing 总被引:1,自引:0,他引:1
The mathematical intractability of the Weibull cumulative exposure model (CE-M) has impeded the development of statistical procedures for step-stress accelerated life tests. Our new model (KH-M) is based on a time transformation of the exponential CE-M. The time-transformation enables the reliability engineer to use known results for multiple-step, multiple-stress models that have been developed for the exponential step-stress model. KH-M has a realistically appealing proportional-hazard property. It is as flexible as the Weibull CE-M for fitting data, but its mathematical form makes it easier to obtain parameter estimates and standard deviations. Maximum likelihood estimates are given for test plans with unknown shape parameter. The mathematical similarity to the constant-stress Weibull model is shown. Chi-square goodness of fit tests are performed on simulated data to compare the fit of the models 相似文献
19.
基于灰色马尔可夫模型的人体健康PH值检测 总被引:2,自引:0,他引:2
文章在灰色预测的基础上,引入马尔可夫预测,建立起灰色马尔可夫预测组合模型。把此模型应用到人体健康尿液PH值的分析预测中。灰色模型预测尿液PH值总的变化趋势,而马尔可夫链预测则适合描述随机波动性较大的预测问题,两者优势互补,形成对PH值的良好预测。 相似文献
20.
《Reliability, IEEE Transactions on》2008,57(3):431-434