Variation rules of the radon emanation coefficient in dump-leached uranium tailing sand

This study was intended to determine the variation rules of the radon emanation coefficient in dump-leached uranium tailing sand. A temperature and humidity controllable device for measuring the emanation coefficient was designed. Tailing sand with different grain sizes was selected from uranium tailings in southern China. An orthogonal experimental design was conducted to determine the radon emanation coefficient of the sand under different temperatures, humidities and grain sizes. Experimental results showed that the air temperature, humidity and grain size have significant effects on the emanation coefficient. The variation rules regarding the radon emanation coefficient showed significant reference value.

     

Study of Σ~*-Δ Interactions

We study the Σ~*-Δ interaction in the chiral SU(3) quark model and in the extended chiral SU(3) quark model.In these two models,the short-range interaction mechanism are totally different,one is from the one-gluon exchange and another is from the vector meson exchange.The possible reasons of forming strangeness-1 bound states are given.Comparisons between the cases with and without quark exchange effect are made.The results show the quark exchange effect does give attractions to (Σ~*Δ)_(ST)=0 5/2 and (Σ~*Δ)_(ST)=3 1/2 systems,which means the special symmetry is important.Also,we make some analysis on chiral field effect,our results show that the σ exchange dominantly provides the attractive interaction for these two states.     

厚钢板焊缝断裂试样疲劳裂纹预制的"高K比法"

提出了预制厚钢板焊缝断裂韧度试样疲劳裂纹的“高K比法”。用“高K比法”预制疲劳裂纹,不需要对焊缝试样进行局部韧带压缩或反向弯曲等预处理,简化了焊接接头断裂韧度试验方法,而且此法不改变原焊缝残余应力,所得到的焊缝断裂韧度值更准确,有效地解决了厚钢板焊接接头韧度评定技术的关键问题。“高K比法”可以缩短断裂韧度试验所需的时间、减少备用试样、节约人力物力。介绍了“高K比法”的试验原理、试验方法、工程应用和意义。     

汽油机燃烧室内温度场测量的激光剪切干涉法

采用激光剪切干涉法测量了汽油机燃烧室内的温度场,并分析了剪切干涉法测温的基本原理,推导出利用干涉条纹图求解温度分布的关系式。在一台二冲程火花点火发动机上设置石英窗和信号同步系统,建立了适合高速摄影的激光剪切干涉测量装置。通过改变剪切干涉量,测取发动机燃烧室内干涉条纹图,从而获得缸内燃烧的二维温度场。结果表明,激光剪切干涉法抗振性强,光路简单可靠,可以进行高速摄像,是研究内燃机燃烧过程的有效方法。从温度场可以看出,燃烧过程中缸内大致可分为三个区,即已燃区、未燃区和燃烧区,具有不同的温度分布和温度梯度。燃烧区温度最高,温度梯度大;已燃区温度次之,梯度较小;未燃区温度最低,但梯度较大。     

THE DIELECTRIC FUNCTION OF AN ELECTRON GAS IN A PERIODIC STRUCTURE: RPA THEORY

The dielectric function of a classical electron gas in a periodic superlattice structure is calculated within the linear response regime undel RPA and the assumption that the equilibrium density of electrons differs slightly from its average value.Numerical results are given for the plasmon dispersion and the longitudinal dielectric function in the case of sinusoidally modulated suprlattice structure.     

THE DIELECTRIC FUNCTION OF AN ELECTRON SYSTEM IN A PERIODIC STRUCTURE: VAA THEORY+

A general expression for the dielectric function of an electron system in a period structure has been derived by using linear response theory with the assumption that the equilibrium electronic density differs slight1y from its average value. Starting from the BBGKY equations,the theory is formulated in the Velocity Average Approximation.Numerical results for the dispersion and damping of plasmons and for the longitudinal dielectric function are given in the case of sinusoidally modulated structures.     

磨料流加工过程中介质黏温特性对金属磨损性能的影响

采用20#钢、45#钢和T8钢3种不同材料进行磨料流加工试验,测定并分析各种材料的磨损量和表面粗糙度的变化情况;通过黏度计研究磨料流加工介质的黏温关系,并基于Rabinowicz单颗粒切削模型推导出以介质黏温关系为主的磨损关系式.结果表明:在磨料流加工开始的几个循环内,材料的表面粗糙度与磨损量变化较大,随着循环次数的增加,其变化幅度逐渐降低;材料硬度越高,磨损量越小;加工介质的黏度随温度升高而急剧下降.推导出的磨损关系式表明,磨损量与介质黏度呈正比,与工件硬度呈反比,材料磨损量变化趋势与试验结果一致.     

In-cylinder temperature field measurement with laser shearing interferometry for spark ignition engines

The temperature field in combustion chamber of spark ignition engine is measured using laser shearing interferometry and high-speed photography in this paper. A set of experimental facility is set up. The relationship equation between the interference fringe image and temperature distribution is deduced. Changing the shearing interferometry quantity, the two-dimensional temperature field of engine combustion chamber and flame propagation can be measured quantitatively by image processing. The test results indicate that the shearing interferometric method has a strong vibration resistance, and a simple and reliable optical path. The temperature distribution and the temperature gradient are different in different zones. The temperature is highest in the burning zone and the temperature gradient is large. The temperature is lower in the burned zone and the temperature gradient is smaller. The temperature is lowest in the unburned zone but the temperature gradient is large. At the initial period of combustion, the flame propagation velocity is low. In the combustion process, the flame front in the approximate spherical shape pushes toward the unburned zone, and the flame propagation velocity starts to decrease. It rapidly increases until it reaches the maximum value as the combustion process going on, and then it gradually decreases until it has burned in the entire combustion chamber.     

求多目标优化问题Pareto最优解集的方法

主要讨论了无约束多目标优化问题Pareto最优解集的求解方法,其中问题的目标函数是C1连续函数.给出了Pareto最优解集的一个充要条件,定义了α强有效解,并结合区间分析的方法,建立了求解无约束多目标优化问题Pareto最优解集的区间算法,理论分析和数值结果均表明该算法是可靠和有效的.     

多孔氧化硅薄膜阴极射线谱的研究

采用近常压下等离子体增强化学气相沉积的方法制备得到多孔氧化硅薄膜,并在沉积区域加载偏压对薄膜形貌和性质进行调制。扫描电镜显示偏压条件下沉积的薄膜更加蓬松多孔,常温下阴极射线谱表明:增大偏压的占空比,CL谱中发光峰的位置并不改变,但谱线强度增大。发光峰的位置说明薄膜中的主要成分是Si-O-Si基团,且该种基团以非桥键的形式存在,薄膜中还存在少量的Si-H键,这与红外光谱测试结果一致。X射线衍射结果表明薄膜中的SiO2是非晶态的。