安全第一标准下基于VaR度量的投资组合优化问题

为了让证券投资者更好地按照自己的安全标准进行投资,根据PYLE H和TURNOVSKY S J提出的安全第一标准,给出在风险价值（VaR）度量下如何选取到最优证券组合的相关结果．其结论对投资者在选择证券投资组合时具有理论上的参考价值．     

ON GENERAL TYPE OF DIGITAL OPTIMAL PREVIEW SERVO SYSTEM

ＯＮＧＥＮＥＲＡＬＴＹＰＥＯＦＤＩＧＩＴＡＬＯＰＴＩＭＡＬＰＲＥＶＩＥＷＳＥＲＶＯＳＹＳＴＥＭ（廖福成）（江上正）（土谷武士）（于欣）ＯＮＧＥＮＥＲＡＬＴＹＰＥＯＦＤＩＧＩＴＡＬＯＰＴＩＭＡＬＰＲＥＶＩＥＷＳＥＲＶＯＳＹＳＴＥＭ￥ＬｉａｏＦｕｃｈｅｎ...     

An approximation for the boundary optimal control problem of a heat equation defined in a variable domain

In this paper, we consider a numerical approximation for the boundary optimal control problem with the control constraint governed by a heat equation defined in a variable domain. For this variable domain problem, the boundary of the domain is moving and the shape of theboundary is defined by a known time-dependent function. By making use of the Galerkin finite element method, we first project the original optimal control problem into a semi-discrete optimal control problem governed by a system of ordinary differential equations. Then, based on the aforementioned semi-discrete problem, we apply the control parameterization method to obtain an optimal parameter selection problem governed by a lumped parameter system, which can be solved as a nonlinear optimization problem by a Sequential Quadratic Programming （SQP） algorithm. The numerical simulation is given to illustrate the effectiveness of our numerical approximation for the variable domain problem with the finite element method and the control parameterization method.     

基于中红外量子级联激光器和石英增强光声光谱的CO超高灵敏度检测研究

采用石英增强光声光谱(QEPAS)技术对CO痕量气体展开检测研究. 为了实现超高灵敏度探测, 采用输出波长为4.6 μm的新颖中红外高功率分布反馈量子级联激光器为光源, 实现了对CO气体基频吸收带的激发与测量. 在优化了调制深度、气体压强和提高了CO分子的振动-转动弛豫速率后, 获得了1.95 ppbv的优异探测极限. 在分析检测结果的过程中, 讨论了能级寿命对信号强度的影响, 并对QEPAS信号强度的表达式进行了修正.     

Investigation of energy transfer from pyrromethene dye to cresyl violet 670 in ethanol

In this paper, radiative and nonradiative energy transfer from laser dye pyrromethene 567 （PM567） and pyrromethene 580 （PM580） as donors to cresyl violet 670 （CV670） as acceptor in ethanol are investigated by using the steady-state emission measurement and the second harmonic generation （532 nm, ～ 13 ns） of a Q-switched Nd：YAG laser as the pumping source. The fluorescence intensity of the acceptor is improved due to the introduction of the donors, and the largest enhancement is obtained to be 128% in the PM567：CV670 dye mixture system. Energy transfer parameters, including the radiative and nonradiative energy transfer rate constants （KR and KNR）, critical distance （R0）, and half quenching concentration （[A]1/2） are investigated using the Stern–Volmer plots, and the acceptor concentration dependencies of radiative and nonradiative transfer efficiencies are also obtained. The values of KR for PM567：CV670 and PM580：CV670 systems are 2032.0×109 L·mol-1·s-1 and 2790.4×109 L·mol-1·s-1, respectively, and the values of corresponding KNR are 3.3×109 L·mol-1·s-1 and 4.2×109 L·mol-1·s-1, respectively. The results indicate that the dominant mechanism responsible for the energy transfer in the dye mixture systems is of the radiative type.     

He-s2（∑u-→X3∑g-)van der Waals体系的从头计算

利用多参考组态相互作用方法计算得到了He-S2(X3∑-g)与He-S2(B3∑-u)的势能曲面;计算并讨论了He原子与S2分子的相对位置R与S2(B3∑-u→X3∑-g)跃迁矩和诱导偶极矩变化的关系;分析了He对S2分子轨道的压缩随R的变化,以及在实验中加入缓冲气体对实现S2分子发光的影响.     

光纤倏逝波型石英增强光声光谱技术

采用块状光学准直聚焦透镜组的传统石英增强光声光谱(QEPAS)技术存在体积难以缩减,结构稳定性不佳,无法适应空间狭小、振动复杂的特殊环境等缺点.基于此,将光纤倏逝波技术与QEPAS技术相结合,提出了一种新型微纳结构光纤QEPAS痕量气体检测技术.实验中,为了提高QEPAS系统信号幅值,优化了石英音叉与激光束的空间位置、激光波长调制深度,同时对比了两种不同共振频率的石英音叉,最终采用共振频率较低的30.720 kHz石英音叉作为声波探测元件,获得的检测极限为6.25×10~(-4)(体积分数),归一化噪声等效吸收系数为4.18×10~(-7)cm~(-1).W·Hz~(-1/2).     

高亮度大功率InGaAIP红光LED芯片研制

报道了大功率高亮度InGaAIP红光LED芯片的设计和工艺制备,实验芯片采用环形插指状电极。和传统的LED芯片相比较,环形插指状电极LED芯片电流扩展分布更均匀,而且更有利于与其它器件的集成。对制备好的芯片进行了I-V特性、光谱特性、光通量和光强的测量。芯片的电性能非常好,其开启电压VT为1．5V;当工作电压达到3V时,工作电流为500mA;在工作电流为350mA时,峰值波长为635nm,半峰全宽为16．4nm。光强为830mcd。在色度学测试中,色坐标为x=0．6943,y=0．3056,显色指数为18．4。因此可以得知高亮度大功率InGaAIP红光LED是未来LED作为普通照明光源应用的第一步,而且将会在科学研究和工业投资的很多应用领域中成为新的焦点。