THE EFFECTS OF ROUGHNESS CHANGE ON THE SURFACE LAYER OF THE ATMOSPHERE(Ⅰ)—THE VARIATIONS OF WIND SPEED AND SHEAR STRESS

A general four-layer structure linear theory for predicting the effects of arbitrarilydistributed roughness change on the variations of wind speed and shear stress in the surfacelayer of3D and2D atmospheres was presented.The results derived by the theory wereagreeable to the previous ones.     

Calculation of the wide-angle neutron spectra from the ~9Be(d,xn) reaction in a thick beryllium target

The multi-layer computing model is developed to calculate wide-angle neutron spectra, in the range from0° to 180° with a 5° step, produced by bombarding a thick beryllium target with deuterons. The double-differential cross-sections(DDCSs) for the ~9 Be(d, xn) reaction are calculated using the TALYS-1.8 code. They are in agreement with the experimental data, and are much better than the PHITS-JQMD/GEM results at 15°, 30°, 45° and 60° neutron emission angles for deuteron energy of 10.0 MeV. In the TALYS-1.8 code, neutron contributions from direct reactions(break-up, stripping and knock-out reactions) are controlled by adjustable parameters, which describe the basic characteristics of typical direct reactions and control the relative intensity and the position of the ridgy hillock at the tail of DDCSs. It is found that the typical calculated wide-angle neutron spectra for different neutron emission angles and neutron angular distributions agree quite well with the experimental data for 13.5 MeV deuterons. The multi-layer computing model can reproduce the experimental data reasonably well by optimizing the adjustable parameters in the TALYS-1.8 code. Given the good agreement with the experimental data, the multi-layer computing model could provide better predictions of wide-angle neutron energy spectra, neutron angular distributions and neutron yields for the ~9 Be(d, xn) reaction neutron source.     

基于D-T紧凑型中子源的快中子照相准直屏蔽体设计及中子束特性模拟研究

中子照相是一种重要的无损检测技术,它能用于火工产品、毒品和核燃料元件等的检测。基于紧凑型D-T中子发生器,完成了一个用于快中子照相的准直屏蔽体系统（BSA）的物理设计。根据D-T中子源的能谱和角分布建立了中子源模型,采用MCNP4C蒙特卡罗程序,模拟了准直屏蔽体系统中中子和γ射线的输运,准直中子束相对于单位源中子的中子注量可以达到9.30×10-6 cm-2,准直中子束中主要是能量大于10 MeV的快中子;在设置的样品平面直径14 cm的照射视野范围,准直束中子注量的不均匀度为4.30%,准直束中中子注量与γ注量的比值为17.20,中子通量和中子注量比值J/Φ为0.992,说明准直中子束有好的平行性;准直屏蔽体外的泄露中子注量率与准直束中子注量率相比降低了2个量级。所设计的准直屏蔽体能满足快中子照相的要求。Neutron radiography is an important nondestructive testing technique. It can be used to detect the explosive devices, drug and the nuclear fuel element, etc. A beam-shaping-assembly (BSA) based on a compact D-T neutron generator is designed for fast neutron radiography in this paper. D-T neutron source model is constructed based on the neutron energy spectrum and angular distribution data. The transportation of neutron and γ-ray in the BSA is simulated using MCNP4C code. The neutron fluence of the collimated neutron beam with respect to the neutron source of the unit source is 9.30×10-6 cm-2. The collimated neutron beams is mainly fast neutrons with energies greater than 10 MeV. In the irradiation field range with a diameter of 14 cm, the neutron fluence uniformity of the collimated beam is 4.3%, the ratio of the neutron fluence to the gamma fluence in the collimated beam is 17.20, and the neutron flux and the neutron fluence ratio (J/Φ) is 0.992 which indicates that the collimated neutron beam has good parallelism. The leakage neutron fluence in outside of BSA is two orders of magnitude lower than that of the collimated neutron beam. The designed BSA can meet the need of fast neutron radiography.     

数字艺术设计中的三维动画教学探讨

介绍了现代数字艺术设计在视觉艺术设计相关行业中的重要性、广泛性,及对视觉媒体的革命性影响.分析了市场需求三维艺术人才的新形势,结合 3ds max 教学形式特征,阐明了实施"人本主义"的创新素质教育理念对艺术设计数字化教学的重要指导作用,确立"以生为本"的教学思理念,将学生培养成一专多能的现代型艺术设计人才的终极目标.     

酿酒酵母高产菌株的木薯酒精产业化生产试验

【目的】对酿酒酵母高产菌株Ygxas-49木薯酒精产业化应用进行试验。【方法】先在200t发酵罐进行分批发酵,对该菌株的各个发酵指标进行评估,再将可行的方案进一步放大至年产12万t酒精生产线上进行生产稳定性试验,最后为考察该菌在产业化应用上的潜力,在200t发酵罐进行高浓度酒精发酵试验。【结果】200t发酵罐分批发酵结果表明:与生产对照菌株相比,酒度提高8.92%,发酵时间减少12h以上,其他发酵指标基本相同。采用该菌株生产酒精可以提高酒度,大大节约发酵时间,增加设备利用率,从而降低酒精生产成本。12万t酒精生产线稳定运行30d结果表明:与生产对照菌株相比,酒度提高5.35%,发酵时间减少10h以上,其他发酵指标基本相同。200t发酵罐高浓度酒精发酵结果:酒度为15.1%(V/V),发酵时间为56h,与目前文献报道最高生产水平(酒度13.5%,V/V;发酵时间69h)相比,酒度提高11.85%,发酵时间缩短13h。【结论】Ygxas-49菌株应用于工业化生产,各项工艺指标均显著优于国内目前最高水平,具有良好的工业化应用前景。     

浅析三维动画艺术的应用现状与发展前景

文章详细介绍了现代计算机三维动画艺术在当代视觉设计相关行业中应用的广泛性,以及对视觉媒体的革命性影响.通过对三维动画与传统的二维动画的艺术表现形式、制作方式的系统描述,阐述了三维动画艺术在视觉艺术传达、媒体设计制作中的高效率、无可替代的技术优势及独特的艺术效果.三维动画艺术已成为现代视觉媒体艺术设计中不可或缺的工具.     

涡方法中的粘性效应

涡方法中粘性效应可通过涡的随机移动或改变涡核尺寸两种途径并入。本文侧重讨论后者。用改变涡核尺寸并入粘性的方法计算了Blasius平板同题,并与Blasius解做了比较。     

Charge sharing effect on 600 μm pitch pixelated CZT detector for imaging applications

We are currently investigating the spatial resolution of highly pixelated Cadmium Zinc Telluride(CZT)detector for imaging application. A 20 mm×20 mm×5 mm CZT substrate was fabricated with 600 μm pitch pixels(500 μm anode pixels with 100 μm gap) and coplanar cathode. Charge sharing between two pixels was studied using collimated a 122 keV gamma ray source. Experiments show a resolution of 125 μm FWHM for double-pixel charge sharing events when the 600 μm pixelated and 5 mm thick CZT detector biased at-1000V. In addition, we analyzed the energy response of the 600 μm pitch pixelated CZT detector.     

流函数Navier-Stokes方程的交替方向部分隐式和完全隐式解法

本文给出了数值求解以流函数表示的Navier-Stokes方程的交替方向部分隐式和交替方向完全隐式方法;作为算例,计算了低雷诺数的二维方腔流动问题,并与已知结果进行了比较。