Inference for step-stress accelerated life tests

In this paper we consider the more realistic aspect of accelerated life testing wherein the stress on an unfailed item is allowed to increase at a preassigned test time. Such tests are known as step-stress tests. Our approach is nonparametric in that we do not make any assumptions about the underlying distribution of life lengths. We introduce a model for step-stress testing which is based on the ideas of shock models and of wear processes. This model unifies and generalizes two previously proposed models for step-stress testing. We propose an estimator for the life distribution under use conditions stress and show that this estimator is strongly consistent.     

从配价理论看“N1是AV的N2”结构的歧义生成

从以往研究中可以发现,“N1是AV的N2”结构有些时候会存在歧义现象。以配价理论为基础,论证这类句子歧义的生成大多是由两种原因造成：一种是由于中心动词和与其共现的配价名词之间出现了复杂的语义关系;另一种是由于中心动词和隐省的配价名词之间出现了复杂的语义关系。     

超薄N6镍板焊接焊缝成形质量研究

当镍及镍基合金板材厚度小于l mm时,在焊接过程中容易出现烧穿、气孔和裂纹等缺陷,严重影响了焊接成形 质量。针对超薄镍及镍基合金的特殊性以及在焊接过程中易出现的问题,采用脉冲微束等离子弧方法焊接0.1 mm厚薄 镍板。文中分析了在一定占空比下,不同脉冲频率和不同基脉比对超薄N6镍板的焊缝成形质量的影响,得到合适的焊 接工艺参数。研究结果表明当基脉比为0.4,脉冲频率为500 Hz时,超薄N6板焊缝成形质量最好。通过该研究成功实 现了0.1 mm厚超薄N6的脉冲微束等离子弧焊接。     

Representations of moments using lower-order conditional moments

Moments and central moments of a random variable X   are expressed as integrals of functions of lower-order conditional moments and the cumulative distribution of X$X$. In particular, sample central moments of order 2k$2k$ are expressed as the sum of between groups variations, providing an analogue to the analysis of variance. Similar expressions are obtained for the expectations of real-valued and measurable functions of X$X$.     

The two-sample -test with a known ratio of variances

We consider the two-sample t-test where error variances are unknown but with known relationships between them. This situation arises, for example, when two measuring instruments average different number of replicates to report the response. In particular we compare our procedure with the usual Satterthwaite approximation in the two sample t-test with variances unequal. Our procedure uses the knowledge of a known ratio of variances while the Satterthwaite approximation assumes only that the two variances are unequal. Simulations show that our procedure has both better size and better power than the Satterthwaite approximation. Finally, we consider an extension of our results to the General Linear Model.     

Estimating the Lyapunov exponent from chaotic time series with dynamic noise

In this paper, we propose an estimator of the Lyapunov exponent of the skeleton for chaotic time series with dynamic noise and prove the consistency of the estimator under some assumptions.     

Does financial development affect income inequality in the U.S. States?

This paper examines the role of financial development on U.S. state-level income inequality in the 50 states from 1976 to 2011, using fixed-effect estimation. We find robust results whereby financial development linearly increases income inequality for the 50 states. When we divide 50 states into two separate groups of above-average and below-average inequality states than the cross-state average inequality, the effect of financial development on income inequality appears non-linear. When financial development improves, the effect increases at an increasing rate for above-average income-inequality states, whereas an inverted U-shaped relationship exists for below-average income-inequality states. To our knowledge, this paper is the first to examine the role of financial development on U.S. state-level inequality.     

基于旋转变压器及TMS320F28035的伺服系统位置检测

为检测伺服系统位置信息,以旋转变压器作为位置传感器,设计了基于芯片AU6802N1的位置检测电路并在此基础上提出了一种仅利用TMS320F28035对旋转变压器转子位置直接解算的方法。该方法综合运用正弦峰值采样、CLA浮点数计算、误差校正等手段。实验表明,该方法在位置解算的速度和精度上可与AU6802N1芯片相比,节约了系统成本,具有一定的实用性。     

“稻-蛙”共作生态农业模式对稻田土壤氮素的影响

通过大田试验,研究了在＂稻-蛙＂共作生态农业模式下土壤中各种形态氮素的动态变化状况.试验结果表明,施肥后土壤中各种形态氮素含量达到最大值,随着时间逐渐增加,其含量均逐渐降低.与处理CK相比,在＂稻-蛙＂共作系统中,土壤中NH＋4-N浓度显著升高,可溶性有机氮含量显著降低,而NO-3-N浓度相当.