Empirical Bayes estimation for queueing systems and networks

Empirical Bayes estimators are derived for standardM/M/1 queues,M/M/1 queues with state-dependent arrival and service rates, finite capacityM/M/1 queues with state-dependent rates and for open Jackson networks. The asymptotic properties of the empirical Bayes estimators are derived both with respect to the conditional distribution of the observations given the parameters, and with respect to the joint distribution of the observations and the parameters.     

氢原子束探针数据采集、存贮和处理系统

本文叙述氢原子束探针数据采集和处理系统,它由电压波形存贮器及APPLEⅡ微机组成。文中给出了典型实验数据和实验曲线。     

Mechanochemical activation of minerals on the cordierite synthesis

The cordierite is commonly prepared by reaction of talc, clay and gibbsite within the range of 1200-1350 °C. This study deals with the effect of the amorphization by grinding of that mixture and its influence on the cordierite formation.The mixture previously mentioned underwent six different treatments: mixing without grinding (A) (only mixing); non-amorphizing grinding (A_M) and amorphizing grinding in oscillating mill at four different times (H samples). The phases formed by thermal treatment were studied using differential thermal analysis (DTA)-thermogravimetric analysis (TG)-DTG, dilatometries and X-ray diffraction (XRD) techniques in certain combinations.The thermal analysis of the A and A_M series were compared and they do not show significant differences, whereas the H samples present remarkable alterations in the DTA peaks as well as in the weight losses (TG). Thus, a great number of DTA peaks tend to decrease the temperature of the maximum and to lower the intensity as the amorphization time increases.Calcination tests performed within the range 900-1200 °C show important differences in the diffractograms obtained from the intermediate products. While at 1350 °C the A and H samples reach the same final phases, within the range 1200-1360 °C they present important differences in the DTA indicating that the sequence and direction of reaction are different. The same behavior can be observed by dilatometric analysis.     

并行分布式检测优化研究

本文研究了多传感器并行分布式检测网的优化问题，它实质上是一种特定的采样信息非充分积累方式下的二元假设检验问题。本文给出了优化条件和优化设计步骤，并介绍了对Ｉ．Ｉ．Ｄ．系统案例分析的结论，使我们对最优设计的困难性有所认识。     

Enrichment of rare-earth elements (REE) and Gd-DTPA in surface water samples by means of countercurrent chromatography (CCC)

An analytical scheme was developed for the determination of rare-earth elements and gadolinium diethylenetriaminepentaacetate (Gd-DTPA) in river water by ICP-MS. Since the concentration of Gd-DTPA and the rare-earth elements in river water is often lower than the limits of detection in quadrupole ICP-MS applying pneumatic nebulization, a preconcentration procedure is essential.In this work, the capabilities of countercurrent chromatography (CCC) for preconcentration of REE were investigated. For preconcentration ethylhexylphosphates as stationary phase had been used. Acidified aqueous samples (pH 2) and river water spiked with REE and Gd-DTPA were under study. The procedure was compared with solid phase extraction (SPE) using the same samples and ethylhexylphosphates as stationary phase. The recovery of the light and middle REE was found to be at about 100%, which was found to be more efficient than applying SPE. In contrast, the recovery rates for Yb and Lu were low (and poorly reproducible) using CCC (57% and 73%, respectively) while significant better results were obtained with SPE (89% and 84%, respectively).The recoveries of Gd applying Gd-DTPA were 80 ± 4% in the investigation of river water samples.     

An investigation of the reliability of the Galerkin-Petrov method with a special study of the helium atom ground state

A convergence characterization of the Galerkin-Petrov method by means of quantities characterizing pairs of subspaces is presented. The usefulness of our approach for setting up reliable computational schemes is demonstrated for the He atom ground state. Several methods of constructing pairs of subspaces for use in quantum chemistry are suggested.     

Time dependence of the NMR line shape for systems with chemical exchange in a zero saturation limit

An expression has been derived for the time dependence of the NMR line shape for systems with many-site chemical exchange in the absence of spin-spin coupling, in a zero saturation limit. The dynamics of variation of the NMR line shape with time is considered in detail for the case of two-site chemical exchange. Mathematica programs have been designed for numerical simulation of the NMR spectra of chemical exchange systems. The analytical expressions obtained are useful for NMR line shape simulations for systems with photoinduced chemical exchange.     

Testing for Drugs in Hair – a Review of Chromatographic Procedures

This article reviews the analysis of drugs and drug metabolites in hair by chromatographic procedures, including the pretreatment steps, and the extraction methods. The general tendency in the last years, to highly sophisticated techniques (GC–MS–NCI, HPLC–MS, GC–MS–MS) illustrates the constant fight for sensitivity.     

做青强度对岭头单枞茶香气成分影响的研究

用气相色谱－质谱法分析了岭头单枞乌龙茶不同做青强度的茶叶香气组分的变化。结果表明，岭头单枞宜用偏轻做青。偏轻做青时芳樟醇及其氧化物含量较高，香气指数（Ｏｗｕｏｒ指数ＦＩ值）较高（达１２９１）。成品经感官审评，蜜韵显著，有花香，符合该品种风格特征，做青强度系数，以机摇系数００３１、全程系数００３８为佳。     

Thermo-oxidative degradation of some elastomers with a high content of 3,4 isoprene units

New elastomers with high content of 3,4 isoprene units have been developed during the last decades in an attempt to ensure superior performances of the final products and the present study is devoted to the investigation of some peculiarities of their ageing behaviour. On thermo-oxidative degradation, 3,4 isoprene units are less affected in comparison to cis-1, 4 and trans-1, 4 isoprene units. The degradation process consists mainly in splitting of the main chains at temperatures of 80–100 °C while at higher temperatures (120–130 °C) branching becomes a significant modification and this reaction is enhanced for the polymers containing preponderantly 3,4 units. Such behaviour leads to the fact that the processability of polymers containing high amounts of 1,2 and 1,3 isoprene units is less affected by thermo-oxidative degradation in comparison with cis-1, 4-polyisoprene, which could be explained by the fact that large amounts of double bonds are not present in the backbone of macromolecules but in the pendent groups.