具有退化工件和老化效应的单机可拒绝排序问题

研究同时具有退化工件和老化效应的单机可拒绝排序问题,即工件的实际加工时间是与其开工时间和所在位置有关的函数,同时生产商可以通过支付一定的处罚费用而拒绝加工某些工件。在生产加工过程中,考虑对机器进行选择性维修活动来提高加工的效率;机器进行维修活动后将恢复到初始状态,老化效应也将重新开始。目标是确定拒绝哪些工件、何时进行维修活动以及接受工件集中工件的次序,以便极小化接受加工工件的最大完工时间与拒绝加工工件总处罚费用的和。证明得到了所研究的问题是NP-难解的,并给出了解决问题的一个全多项式时间近似方案(FPTAS)算法。     

给定密度随机数的生成的通用方法与球面和球体上均匀随机向量的生成法

本文首先介绍基于垂直概率密度表示的,给定密度函数的随机数生成的通用方法;然后介绍球面及球体上均匀随机向量的生成算法。     

A tuneable 600 GHz bandpass-filter with large free-spectral-range

Considering recent ozon problems in the upper atmosphere the measuring technique in the spectral range of about some hundred GHz gains in importance increasingly. Ozon concentration is measured by high sensitive radiometers consisting of several quasioptical components. A tunable bandpass filter represents a versatile component in such a test assembly. The bandpass filter is realized as interferometer and can be adapted to its respective application by individual tuning of its coupling links. Metallic meshes of different aperture size are used for injection and feedback of the electromagnetic wave. A stepper motor control serves for the integration in an automatic measurement setup. The construction principles of the interferometer are summarized. An analysis of the component by means of plane wave theory is extended to a theory of diffraction. Finally the theoretical approach is verified on an application as single-sideband filter comparing the measured results with the computed values of the simulation.     

高纯金属铈的ICP—AES分析和稀土元素间的光谱干扰及其校正

本文采用乙醇预去溶方式进样,ICP-AES直接同时测定了>99.99%的高纯金属铈中5个痕量稀土杂质元素,并讨论了基体量对检测限的影响,稀土元素间的光谱干扰及其校正方法等。当样品溶液中铈的浓度为5mg/ml时,铈中稀土杂质元素的测定下限为:镧、钕和钇0.001%,镨和钐0.003%。其相对标准偏差为1.9～6.4%。     

一特殊情形不可中断的两台可拒绝同型平行机在线排序问题

讨论一特殊情况的两台可拒绝同型机在线排序问题的近似算法.设有两台同型机,工件逐个到达,可以被接受加工,消耗一定的加工时间tj,也可以被拒绝,但要付出一定的罚值pj,目标是要使被加工工件的最大完工时间(makespan)和拒绝工件的罚值之和最小.假设每个工件的罚值和加工长度成固定的比例α∈[0,+∞),即pj=αtj,针对工件加工不可中断情形,设计出算法NPRL,证明其参数竞争比,同时又给出问题下界,它们均为α的分段函数.算法NPRL在α∈0,2 2∪[1,+∞)已达到最优.     

Interference filters from porous silicon with laterally varying wavelength of reflection

Porous silicon reflection interference filters of Bragg type consists of up to 40 quarter wave layers with alternating high- and low-refraction index. The refraction index depends on the porosity of the silicon. The reflection wavelength can vary over a wide range and depends on the thickness and refraction index of the porous layers. A laterally continuously varying wavelength with linear profile of the filter can be achieved by manipulating the porosity and thickness of the silicon in the lateral direction. Our approach is to vary the Fermi level laterally by applying a potential parallel to the surface of the wafer. The slope of the Fermi level is easily controlled by the magnitude of the potential. The lateral current density and thus the porosity and thickness is related to the potential difference between the laterally varying Fermi level and the potential induced by the counter electrode. This relation is the well-known current–voltage characteristic of a Silicon hydrofluoric acid contact. The linearity of the etch profile across the wafer is demonstrated and the properties of preliminary reflection filters are shown.     

法布里—珀罗干涉仪研究光谱线超精细结构的理论分析

在前一篇论文^[1]中,我们提出了利用法布—珀罗干涉仪(以下简称F—P干涉仪)研究光谱线超精细结构的一种新方法。在本文中我们将就表征F—P干涉仪特性的二个参量——自由光谱范围与分辨本领,把它与经典方法^[2,3],作一理论上的分析与比较。其结论是:二者都必须遵守自由光谱范围。但在相同条件下,我们方法所能达到的分辨本领要比经典方法提高一倍。     

卡尔曼滤波ICP－AES法分析稀土元素及其对光谱干扰的校正

本文以卡尔曼（Ｋａｌｍａｎ）滤波ＩＣＰ－ＡＥＳ法进行稀土元素分析，并研究了卡尔曼滤波对其光谱干扰的校正，以及富线基体元素对待测元素、待测元素之间的影响，考察了该方法的检出限、精密度和准确度以及影响滤波的因素。结果表明，该法能有效地消除和校正光谱干扰，减少对分析谱线的选择，改善分析的检出限，分析速度快，结果准确可靠，可适合各种稀土试样（高纯稀土、混合稀土）的日常分析。     

Brauchbarkeit von Mehrelementstandards zur Kalibrierung bei der atomabsorptionsspektroskopischen Wasseranalyse

Zusammenfassung Die Untersuchungen zeigen, daß bei der Bestimmung von Ionen der Elemente Cd, Cr, Cu, Fe, Mn, Pb und Zn mit Hilfe der flammenlosen AAS gegenseitige Störungen auftreten, die durch Zusatz von Salpetersäure verringert, bzw. in einigen Fällen beseitigt werden können. Unter der Bedingung der geringsten gegenseitigen Beeinflussung wurden diese Ionen zu einem Mehrelementstandard kombiniert. Am Beispiel von Wasseranalysen wurde nachgewiesen, daß ein derartiger Mehrelementstandard zur Kalibrierung des Gerätes geeignet ist. Damit können die Bestimmungen mit Hilfe einer Eichkurve bzw. eines Umrechnungsfaktors vorgenommen werden. Die Anwendung des aufwendigen Verfahrens der Standard-Additions-Methode entfällt.

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Use of multielement standards for calibration in water analysis by AAS

Summary Studies have shown that the determination of metal ions like Cd, Cr, Cu, Fe, Mn, Pb, and Zn by means of flameless AAS is a major problem, because of interference of these metal ions with each other. We found that addition of nitric acid helps in eliminating such interferences partially or in some cases completely. By maintaining proper conditions where such influences are minimum, one can combine these metal ions to a multielement standard. By the example of water analysis by flameless AAS, it is shown that such a multielement standard is suitable for the calibration of the instrument. The determination of metal ions can thus be carried out using either calibration curves or conversion factors and avoiding the tedious standard addition method.

     

Pockels effect of water in the electric double layer at the interface between water and transparent electrode

We have obtained the first experimental evidence for the Pockels effect of water, which is induced by a high electric field in the electric double layer (EDL) on the water-transparent electrode interface. The electric-field induced energy shift of the visible interference fringes of a 300 nm indium-tin-oxide (ITO) electrode layer is observed, indicating a negative refractive index change at the interface. Numerical calculation reproduces well the experimental observation, showing that the signal mainly originates from water in the EDL. The Pockels constants of water are estimated to be r₃₃ = 5.1 × 100 pm/V and r₁₃ = 1.7 × 100 pm/V. The large anisotropy of the Pockels effect of water is deduced from the incidence angle dependence of the p-polarization signal. At the same time, the ITO shows a blue shift of the band gap in the UV due to the band population effect in the space charge layer. The plasma frequency in the near IR is also expected to increase due to the band population effect, since the ITO has a high doped carrier population close to metal. A negative refractive index change in the ITO space charge layer is induced from both effects, but its effect on the signal is estimated to be much smaller than that of the negative refractive index change of water in the EDL.