RESAMPLING METHOD UNDER DEPENDENT MODELS

As well known,the jackknife and the bootstrap methods fail for the mean of thedependent observations.Recently,the moving blocks jackknife and bootstrap havebeen proposed in the case of the dependent observations.For the mean of the strictlystationary and m-dependent observations,it has been proved that the proposeddistribution and variance estimators are weakly consistent.This paper proves that thedistribution and variance estimators are strongly consistent for the mean(and theregular functions of mean)of the strictly stationary and m-dependent or(?)-mixingobservations.     

第32届国际数学奥林匹克试题及解答

1.(苏联提供)已给△ABC,设I是它的内心,角A,B,C的内角平分线分别与其对边交于A′,B′,C′。求证     

电磁继电器触点参数的测试

本文介绍了电磁继电器触点电参数的测试方法，包括接触电阻、绝缘电阻参数测试。     

解约束序列极大极小问题的凝聚同伦方法

Consider the constrained sequential max-min problem (CSMMP):     

碰撞问题浅谈

碰撞是一个重要的物理模型，但同学们对此模型的认识和理解有些困难，下面对此问题进行讨论．     

Amplified spontaneous emission properties of a single mode Er3+-doped tellurite fiber

Spectral characteristics of the amplified spontaneous emission(ASE)from a novel single mode Er3+ doped tellurite fiber with D-type cladding is reported in this letter.When pumped at 980 nm,an ASE source that has nearly a 100-nm flat FWHM bandwidth is obtained with a fiber length of 30-60 cm. Variation of ASE spectra with pump powers and fiber lengths are measured.Output power up to 2.0 mW is obtained with a launched pump power of 660 mW.     

一种高温超导磁悬浮装置

本文介绍一个基于倒挂吸引式(EMS)原理的高温超导磁悬浮试验装置．这个装置由高温超导磁体、单臂梁金属导轨、位置传感器、控制电路等组成．绕制超导磁体线圈所用的是Bi-2223／Ag高温超导线材．超导磁体工作在激磁电流为3．2A时，在5mm的空气间隙中产生0．21T的磁通密度，与单臂梁金属导轨可产生72N的垂直悬浮力．通过引入压控电流源，利用常规的超前一滞后校正实现了该磁悬浮装置的稳定悬浮和鲁棒控制，在负载变化87．5%的情况下仍能实现超导磁悬浮装置的稳定悬浮．该试验装置首次验证了高温超导线圈的可控性问题，为进一步探索高温超导线圈用于磁悬浮轨道交通系统的可行性打下了基础．     

回填材料膨润土对放射性气体滞留能力模拟研究

利用各种分析手段对膨润土的物理特性进行了表征 .X射线衍射分析表明钠基膨润土呈典型的六方晶胞 ,晶胞参数是 :a轴 4 .913,c轴 5 .4 0 5 ;差热分析曲线在低温区和高温区有明显的吸热峰出现 ;元素分析钠、钾离子的含量大于钙、镁离子的含量 ,在性能上表现为钠质膨润土具有较强的离子交换能力 ;显微分析表明其表面呈皱隙状 ,测定比表面积高达 2 4 .5 2m2 /g;吸水率测定表明膨胀率大 ,说明它具有密封功能 ,可有效阻滞地下水的渗入 .利用SF6示踪技术 ,通过采集不同时间段取样池样品 ,分析样品中示踪气体浓度 ,绘制取样池示踪气体浓度随时间的变化关系曲线 ,根据费克扩散定律计算扩散系数 .实验结果表明 ,随着压实膨润土密度的增大 ,示踪气体扩散系数迅速减小 ,当密度大于 1.8g/cm3 时 ,扩散系数降至 10 -9m2 /s.研究结果表明 ,膨润土性能优化是通过在膨润土中添加适量的活性炭 ,可明显改善其对气体的阻滞能力 ;增加其对放射性气体滞留能力 ;添加少量的石英砂增加其机械性能、导热性和减少蠕变性 ,将引起对气体阻滞能力的下降 .综合考虑 ,在膨润土中各添加 5 %活性炭和石英砂 ,既对气体具有较好的滞留能力 ,又具有较好的工程特性 .     

Effects of Dual-Electrode Biasing on Er in a Toroidal Plasma

Two externally biased electrodes were inserted into the plasma on the KT-5C tokamak to test the effects on modifying the radial electric field Er, other than single biasing. Using various combinations of biasing voltage,the influences of double biasing are compared with the single biasing. It turns out that the effect of dual-biasing is also effective as a single one, but the outer electrode seems to be shielded by the inner one and show less influence. The results clearly show that the radial electric field Er changed by external biasing is intrinsically an effect localized at the edge of the plasma, which is caused by the electrode induced radial current; and dualelectrode biasing using the method similar to the single biasing seems not to be able to increase more distinctly the peaking effect on Er than the single biasing.