Effect of sodium doping on graded Cu(In1−xGax)Se2 thin films prepared by chemical spray pyrolysis

In the present work we have studied the effect of Na on the properties of graded Cu(In_1−xGa_x)Se₂ (CIGS) layer. Graded CIGS structures were prepared by chemical spray pyrolysis at a substrate temperature of 350 °C on soda lime glass. Sodium chloride is used as a dopant along with metal (Cu/In/Ga) chlorides and n, n-dimethyl selenourea precursors. The addition of Na exhibited better crystallinity with chalcopyrite phase and an improvement in preferential orientation along the (112) plane. Energy dispersive analysis of X-rays (line/point mapping) revealed a graded nature of the film and percentage incorporation of Na (0.86 at%). Raman studies showed that the film without sodium doping consists of mixed phase of chalcopyrite and CuAu ordering. Influence of sodium showed a remarkable decrease in electrical resistivity (0.49–0.087 Ω cm) as well as an increase in carrier concentration (3.0×10¹⁸–2.5×10¹⁹ cm⁻³) compared to the un-doped films. As carrier concentration increased after sodium doping, the band gap shifted from 1.32 eV to 1.20 eV. Activation energies for un-doped and Na doped films from modified Arrhenius plot were calculated to be 0.49 eV and 0.20 eV, respectively. Extremely short carrier lifetimes in the CIGS thin films were measured by a novel, non-destructive, noncontact method (transmission modulated photoconductive decay). Minority carrier lifetimes of graded CIGS layers without and with external Na doping are found to be 3.0 and 5.6 ns, respectively.     

光纤荧光传感器衰减寿命的加权对数拟合法

荧光寿命的检测是荧光光学传感器的核心内容，国际上尝试了多种方法来拟合这种理论上为单指数衰减信号的荧光衰减曲线。这些方法包括非线性函数标准拟合方法。即Levenburg-Marquardt方法，以及Prony方法、FFT方法，对数拟合法等等。为了克服在实际应用中发生的信号退化，需要在测量信号衰减寿命的同时测量信号的初始强度。文章介绍了一种加权的对数拟合法，经计算机仿真及实际数据测试均可以得到和Levenburg-Marquardt方法非常接近的结果，且拟合时间大大缩短，测量稳定性大大提高。仿真测试及具体实验测试结果显示了这种方法的有效性。该方法不仅与Levenburg-Marquardt方法的偏差曲线非常相似，而且实验测得的荧光寿命与Levenburg-Marquardt方法偏差在0．2％以内。     

Mining for trigger events with survival analysis

This paper discusses a new application of data mining, quantifying the importance of responding to trigger events with reactive contacts. Trigger events happen during a customer’s lifecycle and indicate some change in the relationship with the company. If detected early, the company can respond to the problem and retain the customer; otherwise the customer may switch to another company. It is usually easy to identify many potential trigger events. What is needed is a way of prioritizing which events demand interventions. We conceptualize the trigger event problem and show how survival analysis can be used to quantify the importance of addressing various trigger events. The method is illustrated on four real data sets from different industries and countries.     

非接触式半导体少子寿命测试方法——微波反射法

介绍了一种非接触式用于测量少子寿命的微波反射法，并与通常的光电导衰退法进行了比较。     

Determination of generation lifetime fromC-t transients under linear voltage ramp bias

When a linear voltage ramp is applied to the gate of a MOS capacitor, a capacitancetime (C-t) transient is observed. The MOS capacitor is biased into strong inversion before applying the voltage ramp in order to eliminate surface generation. FromC-t transient curve obtained experimentally the minority carrier generation lifetime in semiconductor can be determined. The experimental results show that for the same sample the lifetimes extracted fromC-t curves under varying voltage sweep rates are close each other, and they are consistent with the lifetimes extracted by saturation capacitance method.     

注硼中子寿命测井技术在华北油田的应用与发展

注硼中子寿命测井技术是近几年发展起来的一项用于测量开发井水淹状况 ,分析层间油水关系 ,根据其结果采取合理措施降水增油的新技术。该技术在华北油田推广应用以来 ,取得了较好的效果。在应用过程中 ,不断优化选井原则 ,优选注硼参数和测注工艺 ,突出综合对比解释 ,进一步提高了工艺技术应用的合理性、准确性以及解释结果的吻合性 ,一定程度上丰富了注硼中子寿命测井理论 ,促进了该项技术的完善与提高     

注硼中子寿命测井注硼工艺优化设计

注硼中子寿命测井是一项水淹层测井新技术 ,对老油田的产层分析评价、剩余油含量估算等方面发挥了重要的作用。但测井施工时 ,往往由于注硼工艺不当导致硼酸的渗吸量难以准确反映地层可动水的含量 ,从而产生解释上的困难和误区。在渗流与扩散理论相结合的基础上 ,结合华北油田的施工实践 ,介绍了确定注硼管柱、硼酸用量、注硼压力以及硼酸扩散时间的基本原则和实际经验 ,为工艺的优化设计提供了一些方法与思路     

Effect of doping polyacrylic acid with some dopants as studied by different techniques

The molecular weight of polyacrylic acid (PAA) was determined by a viscometric method using NaNO₃ as solvent at 30°C. The specific electric conductivities (σ) of PAA as well as PAA doped with carbon black (CB), chromium oxide (Cr₂O₃), and cupferron with different concentrations (from 0.25 to 1 wt %) were measured at a temperature range 360–400 K. IR spectra of some polymers were determined and it was shown that when PAA was doped with 0.5 wt % CB, a C? O? C band appeared at 775–875 cm^?1. The positron annihilation lifetime (PAL) spectra in PAA doped with the above‐mentioned dopants were measured as a function of their concentrations. It was observed that the short lifetime intensity I₁ decreased, whereas the intermediate lifetime intensity I₂, which is related to the conductivity of the material, increased with increasing the wt % of Cr₂O₃ and cupferron as well as at low concentrations of CB. These results are discussed in terms of the conducting island model. It was found that there were distinct positive relationships between σ and I₂. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 877–883, 2002; DOI 10.1002/app.10381     

延长分米波电视发射管使用寿命的探讨（上）

文章从原理上讨论了影响分米波电视发射管寿命的若干因素。并提出了若干延长寿命的建议：（１）正确的灯丝加热方法是行之有效的措施，经验证明：过分强调降低灯丝电压往往得到相反的效果。（２）必须有良好的冷却方式。（３）通过对帘栅电路的分析，说明对此电路必须作很好的处理以消除故障和防止寄生振荡。     

A time series approach to fatigue crack propagation

The inherently nonlinear phenomenon of fatigue crack propagation is modeled as a linear random process. To a first approximation, simple, nonstationary time series models are introduced and standard techniques for determining the parameters of autoregressive integrated moving-average processes are applied. Multiplicative time series models are next utilised for the representation of a group of crack history curves. Implementation of the models on the Virkler experimental data set yields satisfactory results. Reliable Gaussian approximations to the distribution of the time required by a crack to reach a specified critical length are obtained, and the usefulness of the approach is demonstrated when updating lifetime predictions after periodic inspections.