基于3种图像处理方法的杨树木材表面孔隙度比较

以转基因欧洲黑杨、北抗杨、转基因741杨和107杨为研究对象,通过图像处理后的色域分析,测量了木材表面孔隙度,并与Image-Pro Plus图像分析法和直线测量法进行比较。结果表明,Image-Pro Plus图像分析法可以直观获得木材横切面上管孔大小数值,但难以测量木材表面孔隙度;直线法虽然简化了测量工作,但仍旧耗费时间;基于图像处理的色域测定法在图片导入后可以即时获取木材表面孔隙度信息。色域测定法和直线测量法结果相当,4种杨树木材表面孔隙度大小依次为转基因欧洲黑杨>北抗杨>转基因741杨>107杨,其中直线测量法结果为75.91%、72.88%、70.73%、69.98%,色域测定法结果为70.61%、68.56%、65.56%、65.26%,Image-Pro Plus图像分析法测定管孔所占比率分别为20.76%、20.92%、22.64%、26.81%。

不同烧结次数对氧化锆陶瓷修复体强度的影响

目的评价不同烧结次数下的氧化锆陶瓷块的强度指标,并利用轮廓投影仪观测陶瓷表面的孔隙度,旨在揭示不同烧结次数对其强度的影响程度。方法用Upcera氧化锆锆块切削成相同规格(25mm×5mm×2mm)的样品瓷块30块,分为6组,每组5个样品,随机分为A、B、C、D、E、F六组,每组烧结次数依次为2、3、4、5、6、7次。按照YY0716-2009标准的要求,用夹具将陶瓷样品固定在万能试验机上,进行相关强度测试并记录测试结果,测试项目包括弯曲强度;利用轮廓投影仪观察表面孔隙度。采用SPSS软件对不同测得强度结果和孔隙度进行非参数统计学方法分析和组间比较的q检验分析。结果六组氧化锆试样烧结2、3、4、5、6、7次后,随着烧结次数的逐步增加,用放大100倍轮廓投影仪观察表面孔隙度,其孔隙分布范围逐渐增大,孔径逐渐减小。多次烧结后氧化锆试样弯曲强度分别为(997±145)Mpa;(999±120)Mpa;(1 019±51)Mpa;(1 008±115)Mpa;(1 007±120)Mpa,试样材料的三点弯曲强度经过多次烧结后无明显改变,各处理组间强度差异无统计学意义(P=0.97567)。结论随着烧结次数的增加,氧化锆内部晶体结构影响较大,但对氧化锆弯曲强度几乎无影响,氧化锆材料应该在口腔修复领域得到广泛的应用。

采用气体吸附法分析载体硅胶的孔隙结构

采用NOVA 2000 e型比表面积及孔隙度分析仪测定载体硅胶的比表面积和孔隙结构,考察了该方法的准确性和重复性,并对自制GC,进口955及LG 3种载体硅胶样品进行了测定,利用BJH法和NLDFT法对硅胶的孔径分布进行了计算。结果表明,该方法的测试结果准确,被测样品的比表面积、总孔容和平均孔径测定结果的相对标准偏差均小于2%;3种硅胶样品均含有圆柱状且孔径分布较窄的中孔,GC硅胶的比表面积和总孔容均较2种进口硅胶偏大;GC硅胶和955硅胶的孔径分布更接近,而LG硅胶的孔径分布范围相对更窄且孔隙分布更均匀。

Spatial Structure Characteristics Detecting of Landform based on Improved 3D Lacunarity Model

The spatial structure characteristics of landform are the foundation of geomorphologic classification and recognition.This paper proposed a new method on quantifying spatial structure characteristics of terrain surface based on improved 3D Lacunarity model.Lacunarity curve and its numerical integration are used in this model to improve traditional classification result that different morphological types may share the close value of indexes based on global statistical analysis.Experiments at four test areas with different landform types show that improved 3D Lacunarity model can effectively distinguish different morphological types per texture analysis.Higher sensitivity in distinguishing the tiny differences of texture characteristics of terrain surface shows that the quantification method by 3D Lacu-narity model and its numerical integration presented in this paper could contribute to improving the accuracy of land-form classifications and relative studies.

Micromorphology of Surface Crusts in the Knersvlakte,South Africa

Soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern Africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples （n = 67）. This analysis showed that infiltrability is potentially maximal at low water- dispersible ＇clay plus silt＇ content and low silt content （r^2 = 0.72 and 0.64; respectively, n = 67） （Figure 2）. The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and ＇clay plus silt＇ content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections （n = 6） （circular and parallel polarizers）. Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability （〈 100 mm·hr^-1, n = 4） had greater crust strength, lower porosity （both total and in the least porous slice） and greater water-dispersible ＇day plus silt＇ and silt content than the porosity samples with high infiltrability （〉 100mm·hr^-1, n = 2）. The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands （〈 0.5 mm in width） with relatively few air vesicles. The porosity samples with horizontal slices of low porosity （but large numbers of air vesicles） had low infiltrability, while those without slices of low porosity （and relatively few air vesicles） had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the pedoderm.

容量法测量5A分子筛静态吸附CH4、CO和CO2的研究

采用容量法分别测量CH4、CO和CO2在5A分子筛上的等温吸附曲线,探究吸附温度和吸附压力对CH4、CO和CO2吸附量的影响。实验结果表明,吸附量随着吸附压力的上升逐渐增大。设定吸附温度在30℃、50℃和70℃时,5A分子筛在30℃时对CH4吸附量最大,为13.60cm3·g-1;对CO和CO2吸附量均在50℃时呈现最大值,分别为17.68cm3·g-1和94.38cm3·g-1。而吸附温度70℃时,对3种气体的吸附量均减小。

Changes of Porosity and Roughness of Concrete Surfaces Due to Microbial Corrosion

The issue of the building materials biocorrosion has a significant economic dimension because it results in the costly repair. The start and the course of corrosion are conditioned by many factors which undoubtedly include biological effects like the influence of vegetation and microorganisms causing the so called microbial corrosion. Microorganisms have also a considerable share in the decay and degradation of different building materials. The activity of sulphuratum is the keystone of many processes in nature and in industry. The sulphuric bacteria oxidize hydrogen sulphide produced by sulphate-reducing bacteria into sulphuric acid resulting in the acid or sulphate corrosion of cement stone. The paper is aimed on evaluation of porosity and roughness of concrete samples surface as elementary characteristics of microbial corrosion. After 4 months exposure to the real conditions in sewers deposition the changes were observed by confocal laser microscopy and consequently analyzed and interpreted.

Formation of Polyethersulfone Film with Regular Microporous Structure by Water Vapor Induced Phase Separation

Polyethersulfone(PES)film with regular microporous structure was formed using dichloromethane as the solvent via water vapor induced phase separation(VIPS).The effects of solution concentration,atmospheric humidity and temperature,as well as molecular weight of PES on the surface morphology of the polymer film were investigated.The surface morphology characterized by SEM showed that the pore size reduced as the solution concentration increased.There was an optimum range of relative humidity for the formation of regular pore structure, which was from 60%to 90%at concentration of 20 g·L-1 and 20°C.With the atmospheric temperature varied from 20 to 30°C,the pore became larger and the space between pores increased.The pore size in the PES film with low molecular weight was smaller than that with high molecular weight.

Energy analysis of stability on shallow tunnels based on non-associated flow rule and non-linear failure criterion

On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth.

Pore-scale study based on lattice Boltzmann method of density driven natural convection during CO_2 injection project

Saline aquifers are chosen for geological storage of greenhouse gas CO_2 because of their storage potential.In almost all cases of practical interest,CO_2 is present on top of the liquid and CO_2 dissolution leads to a small increase in the density of the aqueous phase.This situation results in the creation of negative buoyancy force for downward density-driven natural convection and consequently enhances CO_2 sequestration.In order to study CO_2 injection at pore-level,an isothermal Lattice Boltzmann Model(LBM) with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment.The present analysis showed that after the onset of natural convection instability,the brine with a high CO_2 concentration infringed into the underlying unaffected brine,in favor of the migration of CO_2 into the pore structure.With low Rayleigh numbers,the instantaneous mass flux and total dissolved CO_2 mass are very close to that derived from penetration theory(diffusion only),but the fluxes are significantly enhanced with high Ra number.The simulated results show that as the time increases,some chaotic and recirculation zones in the flow appear obviously,which promotes the renewal of interfacial liquid,and hence enhances dissolution of CO_2 into brine.This study is focused on the scale of a few pores,but shows implications in enhanced oil/gas recovery with CO_2 sequestration in aquifers.