快速计算任意振动体辐射声场的边界单元法

在运用边界单元法离散Ｈｅｌｍｈｏｌｔｚ积分方程的基础上，采用远场近似，提出了一种快速求解任意振动物体辐射声场的数值计算方法。并用该法对实例进行了计算和分析。     

聚酯型聚氨酯化学组成的研究

本文报导了聚酯型聚氨酯水介和分离方法,经红外光谱(IR)、核磁共振氢谱和碳谱(H—NMR和~(13)C—NMR)鉴定,未知样品(系化工部二局提供进口PU型粘结剂)水介产物的化学组成是4,4′—二氨基二苯基甲烷、1.4—丁二醇和已二酸。     

有机钴胺素的合成及光谱研究

本文使用Schrauzer法合成了多种有机钴胺素,测定了紫外-可见吸收光谱,提出了判断有机钴胺素生成的光谱证据。     

Unmixed local rings with minimal Hilbert-Kunz multiplicity are regular

We give a new and simple proof that unmixed local rings having Hilbert-Kunz multiplicity equal to must be regular.

     

Transcendence of Certain Trigonometric Series

In this paper the transcendence of values of certain trigonometric series with algebraic coefficients and its derivatives at algebraic points is proved under a general condition dependent only on the coefficients. The proof of the theorem is based on a criterion for linear independence over a number field. Received November 9, 1999, Accepted February 5, 2001     

Combined cation-exchange and extraction chromatography for the concomitant separation of Zr, Hf, Th, and the Lanthanides from geological materials

A new method was developed, aiming to overcome the iron and titanium interferences which severely limit the applications of a recently introduced extraction chromatography material, referred to as RE resin (formerly, RE Spec), to the analysis of geological samples. The separation scheme is based on the combined use, in tandem columns, of the conventional AG50WX4 cation-exchange resin and the RE extraction chromatography material, without any intervening evaporation step. The Lanthanides are recovered quantitatively, while recoveries for Zr, Hf and Th range from 94 to 98%. These three elements are determined using the isotope dilution method, thereby alleviating the need for a yield correction. Compared with conventional methods based on cation-exchange, this combined scheme offers a greater multi-element capability, significant miniaturisation, acid wastes reduction, and a higher degree of purity of the separated analytes with regard to unwanted elements such as Ba and residual Ca and Al. This concomitant isolation of 17 trace elements of great interest in the Earth and Environmental Sciences, achieved with excellent recoveries and satisfactory blank levels, can be used prior to high precision analysis of ultra-trace elements in geological samples by ICP-Mass Spectrometry.     

Regularities of formation and lattice distortion of perovskite-type compounds

Based on 489 known perovskite-type complex oxides and a number of other type complex oxides, the pattern recognition-atomic parameter method is adopted to find regularities of the formation and the lattice distortion of the perovskite structure. It has been found that the restriction on Goldschmidt's t factor constitutes only a necessary but not a sufficient condition to form perovskite-type compounds. A more effective mathematical model, which can precisely sum up the regularities of the formation, the lattice distortion,and the cell constants of known perovskite-type compounds and reliably make corresponding predictions on unknown compounds, can be set up by integrating multiple atomic parameters such as ionic radii, ionic valency, and Basanov's electronegativity of constituent elements. Based on it, an intelligent database has been implemented. Its prediction accuracy is tested by eight newly discovered perovskite-type compounds such as Eu(Mn0.5 Ni0.5)O3, etc. (they are not included in the database during the test). The prediction resuits are in agreement with experimental facts.     

Vegetation reconstruction of Bronze Age by using microscopic structure of charcoals

The microscopic structure of charcoals was determined in two sites of Bronze Age, Chifeng area by using the scanning electronic microscope. The results showed that these charcoals are all timbers of Mongolian oak (Quercus mongolica). It has powerful climatic indicative significance. Based on the assemblage of pollen composition, their eco-climatic index and character of community, the vegetation reconstruction of Bronze Age was obtained. The reconstruction showed that the zonal vegetation was Mongolian oak forest and Chinese pine forest in the loess hills in the Chifeng area, which suggested that the climatic condition was warmer and wetter at that time than present time.     

Investigation on Relationship between Cost and Software Reliability

Based on the fact that the software development cost is an important factor to control the whole project, we discuss the relationship between the software development cost and software reliability according to the empirical data collected from the development process. By evolutionary modeling we get an empirical model of the relationship between cost and software reliability, and validate the estimate results with the empirical data.