模糊聚类分析法在水质监测断面优化中的应用

以巢湖环湖11条河流共28个断面监测断面2005～2009年5年的污染指标的监测平均值作为原始数据,采用SPSS模糊聚类分析法对不同监测断面进行聚类分析,确定各监测断面间的亲疏关系,并根据断面属性等实际情况,最终将原28个断面初步优化调整为23个断面。     

二次曲线透射结构的分析

所有二次曲线皆为射影形,它们之间存在建立透射结构的可能性。本文从二次曲线问透射性质,分析了建立透射结构的条件,以及各种典型位置的透射结构形式,从而提出了对应曲线的作图。     

Q800高强钢焊接工字形截面残余应力试验分析

为研究Q800高强钢焊接工字形截面的纵向残余应力分布规律,采用线切割法对4个试件进行试验研究,分析腹板和翼缘板件宽厚比对残余应力的影响,研究各板间残余应力的相互影响及其自平衡性,提出Q800高强钢焊接工字形截面的残余应力分布模型和计算公式. 结果表明,Q800高强钢工字形截面的残余应力分布形式与普通强度钢材的一致. 焊缝和火焰切割边附近呈现残余拉应力,且随着宽厚比的变化呈不规律变化;翼缘外伸部分中部和腹板中部都呈现基本恒定的残余压应力,且随着板件宽厚比的提高而相应减小;其余部位是从残余拉应力到残余压应力转变的过渡区域;翼缘和腹板内的残余应力基本满足自平衡条件,二者没有相互间的影响作用.     

Ultrasonic technique as tool for determining physical and mechanical properties of frozen soils

Ultrasonic velocities of compressional and shear waves in frozen sand, silty-sand and silt were measured at subfreezing temperature and the relationship between acoustic and physical-mechanical properties examined. Ultrasonic measurements revealed that the influence of temperature on ultrasonic velocities is due to the phase transition from water to ice. Different methods were proposed to determine the amount of unfrozen water in frozen soils. The unfrozen water content was measured directly by time domain reflectometry and compared to predicted values using different theoretical approaches. The prediction models showed good agreements with measured values at low temperatures. However, the shape of the curves obtained did not completely satisfying as the estimated unfrozen water fraction near 0 °C was significantly greater than the measured values. Finally, based on the elastic wave theory and measured acoustic velocities the elastic constants of the frozen soils were calculated. The changes in elastic constants were found to be related to the increase in ice content, ice stiffness by ice cementation and a decrease in unfrozen water content.     

Reaction of Cerium Oxide with Zirconium and Yttrium Oxides at 1250°C

Phase relationships in the ternary system ZrO₂ Y₂O₃ CeO₂ were investigated by x-ray diffraction analysis and electron microscopy for the first time, and phase relationships in the binary systems ZrO₂ CeO₂ and CeO₂ Y₂O₃ defined more accurately at 1250°C over the entire range of concentrations. The 1250°C isothermal section of the phase diagram for ternary system was constructed. Specimens were prepared from nitrate solutions by evaporation, drying, grinding, and subsequent annealing at 1250°C. The systems were characterized by the formation of broad solid solution ranges based on C -Y₂O₃, F-CeO₂, F-ZrO₂, and narrow based on T-ZrO₂ and -phase. No new phases were found in the systems. The path of isoparametric lines in the F-ZrO₂ solid solution field suggests that yttrium and cerium ions can substitute for each other without appreciable substitution of zirconium ions.     

Broad-Crested Weirs with Rectangular Compound Cross Sections

A series of laboratory experiments was performed in order to investigate the effects of width of the lower weir crest and step height of broad-crested weirs of rectangular compound cross section on the values of the discharge coefficient, the approach velocity coefficient, and the modular limit. For this purpose, nine different broad-crested weir models with rectangular compound cross sections and a model with a rectangular cross section were tested in a horizontal laboratory flume of 11.0 m length, 0.29 m width, and 0.70 m depth for a wide range of discharges. The compound cross sections were formed by a combination of three sets of step heights and three sets of lower weir crest widths. The sill-referenced heads at the approach channel and at the tailwater channel were measured in each experiment. The dependence of the discharge coefficient, approach velocity coefficient, and modular limit values on model parameters was investigated, and these quantities were compared with those of the broad-crested weir models with a rectangular cross section.     

利用土壤切片及数字图像研究低丘缓坡不同部位土壤的孔隙结构特征

利用土壤切片及数字图像技术 ,初步研究了葡萄种植园低丘缓坡不同部位 (坡顶、坡中和坡底 )土壤的孔隙结构特征。结果表明 :孔隙面积随着深度的增加而减小 ,孔隙构成以直径小于 1mm的小孔隙为主 ,且随着深度增加小孔隙比重增加 ,不同部位孔隙结构具有一定的差异 ,这也说明了采取水土保持措施的必要性     

Electron-Impact Total Ionization Cross Sections of Molecular Ions

The Binary-Encounter-Bethe (BEB) model for electron-impact total ionization cross sections of neutral molecules has been modified for molecular positive ions. The total ionization cross sections for H2+, N2+, CD⁺, and CO⁺ from the modified BEB formula are compared to available experimental data. The theory is in good agreement with experimental data on H2+, N2+, and CD⁺, but the experimental data by Belic et al. on N2+, and CO⁺ are lower than the theory. The large difference between the theory and experiment on CO⁺ is a strong indication of the dominance of the dissociative ionization channel, CO⁺→C⁺+O⁺, which was not included in the experiment.     

WTO — a deterministic approach to 4-fermion physics

The program WTO, which is designed for computing cross sections and other relevant observables in the e⁺e⁻ annihilation into four fermions, is described. The various quantities are computed over both a completely inclusive experimental set-up and a realistic one, i.e. with cuts on the final state energies, final state angles, scattering angles and final state invariant masses. Initial state QED corrections are included by means of the structure function approach while final state QCD corrections are applicable in their naive formulation. A gauge restoring mechanism is included according to the Fermion-Loop scheme. The program structure is highly modular and particular care has been devoted to computing efficiency and speed.