广义双二项风险模型的破产概率和Lundberg不等式

本文将双二项分布风险模型推广到资金利率和通货膨胀率下带干扰的新模型--广义双二项风险模型.然后讨论了盈余过程的性质并利用盈余过程的性质获得了广义双二项风险模型的破产概率和Lundberg不等式,最后就保费额服从混合指数分布的情况进行了分析.     

First-Principles Calculations of Elastic Constants of Superconducting MgB2

The five independent elastic constants of superconducting MgB2 are obtained using the first-principles plane wave method with the new relativistic analytic pseudopotential of the Hartwigsen-Goedecker-Hutter (HGH) scheme in the frame of local density approximation. The dependences of bulk modulus on temperature and pressure are also obtained. It is suggested that the HGH-type pseudopotentials are successful in investigating the ground-state mechanical properties of any solids.     

新体制引信干扰机理分析

为应对新体制无线电引信带来的威胁,从引信对抗角度以超宽带无线电引信为研究对象,研究干扰作用下其失效机理。揭示了超宽带无线电引信敏感干扰波形响应机理,理论推导了周期调制干扰信号作用下引信响应特性,仿真计算了在射频噪声、正弦波调幅、正弦波调频以及扫频正弦波调幅干扰信号作用下超宽带引信接收机相关器输出响应特性。以干信比增益为表征参量,通过理论计算、仿真及试验验证得出结论:周期类调制干扰中调幅类干扰对超宽带引信干扰效果最好。     

超高效液相色谱-串联质谱多目标分析生物样品中的微量内分泌干扰污染物

建立了生物样品中9种微量内分泌干扰物(EDCs)的多目标分析方法.采用旋涡振荡-超声波辅助萃取,结合凝胶渗透色谱(GPC)除去大分子有机物干扰,再经硅胶柱层析进一步净化,最后应用超高效液相色谱-串联质谱(UHPLC-MS/MS)检测.GPC采用乙酸乙酯-环己烷混合溶液(1:1,V/V)为流动相,选择12~28 mL为目标化合物馏分的收集段;质谱采用电喷雾离子源正离子模式和大气压化学电离源负离子模式,数据采集为多重反应监测模式.方法回收率为65.2%~118.0%,定量限为0.1~9.7 ng/g dw(干重).采用本方法初步分析了珠江水系鲤鱼脊肉中的内分泌干扰污染物,结果表明,除均二苯腺和三氯卡班未被检出外,其它内分泌干扰污染物的含量为0.1~22.6 ng/g dw.     

固相萃取-液相色谱-离子阱二级质谱法同时测定饮用水中多种痕量有机污染物

建立了高效液相色谱-离子阱二级质谱法同时测定饮用水中内分泌干扰物、农药残留和丙烯酰胺等15种痕量有机污染物的方法。250mL水样先用C18固相萃取柱富集,经梯度洗脱液相色谱分离,采用时间分段的方法确定各组分质谱检测条件,利用离子阱二级质谱进行测定。所检测的15种有机污染物定量线性关系良好,相关系数为0.9975～0.9998,检测限在0.2～20ng/L之间。在低、中、高3个不同加标水平下,实际水样的加标回收率为75.1%～99.5%,相对标准偏差为4.6%～12.3%。该方法成功用于5种不同来源饮用水样的检测,获得了满意结果。     

大带隙二维三角格子光子晶体结构参数的优化设计

光子晶体结构设计优化是理论研究的一个重要内容.运用平面波展开法对圆柱、方柱及正六边柱构造的二维三角格子光子晶体的禁带进行仿真计算,讨论了介质材料分别为GaAs、Si和Ge情况下,柱子形状、旋转角度、填充比的变化对完全光子禁带的影响.发现:对于二维三角格子光子晶体,相对于介质柱,空气柱更易获得完全光子禁带;而相对于圆柱及...     

Theoretical study on the Rocksalt structured positron annihilation in magnesium oxide

Based on the atomic superposition approximation （ATSUP） and first-principles pseudopotential plane-wave methods, the bulk and Mg mono-vacancy positron lifetime of magnesium oxide were calculated using Arponen-Pajamme and Borofiski-Nieminen positron-annihilation-rate interpolation formula respectively. The calculated values are in good agreement with experimental values and the first-principles method gives more convincing results. The positron annihilation density spectra analysis reveals that positrons mainly annihilate with valence electrons of oxygen atoms when the magnesium-vacancy appears within magnesium oxide.     

Method of sensitivity improving in the non-dispersive infrared gas analysis system

A method of interference correction for improving the sensitivity of non-dispersive infrared (NDIR) gas analysis system is demonstrated. Based on the proposed method, the interference due to water vapor and carbon dioxide in the NDIR NO analyzer is corrected. After interference correction, the absorbance signal at the NO filter channel is only controlled by the absorption of NO, and the sensitivity of the analyzer is improved greatly. In the field experiment for pollution source emission monitoring, the concentration trend of NO monitored by NDIR analyzer is in good agreement with the differential optical absorption spectroscopy NO analyzer. Small variations of NO concentration can also be resolved, and the measuring correlation coefficient of the two analyzers is 94.28%.     

Experiment on 60-GHz MMW transmission performance in an optical fiber and wireless system

We experimentally investigate the transmission performance of 60-GHz signals over standard single-mode fiber (SSMF) and wireless links at different bit rates. Experimental results show that in a transmission of over 10-km SSMF and 1.3-m wireless link, bit rate reaches up to 5 Gb/s and bit error rate (BER) is less than 10 4 . The main limiting factor in such radio-over-fiber (ROF) systems is intersymbol interferences caused by the so-called walk-off effect when BER is below 10 8 . In addition, a transmission of over 20-km SSMF without chromatic dispersion compensation is briefly investigated. For a BER of 10 8 , the optical penalty is 2 dB.     

新型高效偏振光分束器的设计

研究及分析了光波在分束结构中的传播行为和特性,发现当增大波导邻近两侧空气孔半径时,能形成完全光子禁带范围内某一频率光波单一偏振态的传播,基于此原理提出了一种全新结构的偏振光分束器,计算与模拟结构表明,该结构可以实现TE模与TM模高效大角度分离. 器件尺寸不超过17.6 μm×9.8 μm,在集成光回路中无疑有着很大的应用潜力. 关键词： 光子晶体 偏振光分束器 时域有限差分法 平面波展开法