渐开线齿轮廓线生成动态仿真及其应用

渐开线齿轮廓线难以精确绘制,尤其是存在齿根过渡曲线变化较大的问题。为此,提出一种基于VBA和AutoCAD ActiveX技术的动态模拟齿轮加工方法,通过动态绘制齿轮坯与齿条刀具间的相对位置,形象演示齿轮渐开线和齿根过渡线的形成过程。用动态模拟的方法得到的齿轮廓线精确度高,可直接用于齿轮三维的精确造型。     

台湾海峡及其邻近海域软水母亚纲二新种记述

记述了采自台湾海峡侧丝水母属(Helgicirrha Hartlaub,1909)——卵形侧丝水母,新种(H.ovalis sp.nov.)和采自邻近海域厦门同安湾似杯水母属(Phialella Brown,1902)——厦门似杯水母,新种(P.xiamenensis sp.nov.).这2种鉴别特征如下:卵形侧丝水母,新种,伞扁于半球形,伞薄;胃柄短;生殖腺卵圆形,位于辐管近中部;8条触手,每条触手有3对侧丝,无排泄乳突;每2条触手间1～2个缘疣,各具1对侧丝,其末端有黑色素.厦门似杯水母,新种,伞扁于半球形,伞薄;胃小,口方形;生殖腺球形或椭圆形,悬挂于辐管近伞缘,有中沟;16条空心触手,触手基部球形;8个平衡囊,在伞缘环管垫状疣突上.     

Lipids of sulfate-reducing bacteria and sulfur-oxidizing bacteria found in the Dongsheng uranium deposit

U-bearing sandstones from the Dongsheng deposit in Ordos Basin contain abundant C15-C18 fatty acids. The fatty acids may have been derived from modern and ancient organisms including organisms from the intervals of U mineralization. A certain amount of i15:0, a15:0, a17:0 fatty acids coexist with small amounts of i17:1ω7c and 10me16:0, characteristic biomarkers of Desulfovibrio and Desulfobacter sp., respectively. This indicates the existence of sulfate-reducing bacteria (SRB) in the sandstones. The presence of sulfur-oxidizing bacteria (SOB), such as Beggiatoa and Thioploca, is indicated by significant amounts of 16:1ω7c and 18:1ω7c fatty acids. The existence of the SRB in the deposit, as inferred from the fatty acids, is consistent with results from fossilized microorganisms and isotopic compositions of ore-stage pyrite. This suggests that the environment may have been favorable for the SRB to grow since ore formation (9.8-22 Ma). The bacteria may have degraded hydrocarbons directly, or indirectly utilized hydrocarbons degraded by oxic microbes in the deposits. This process may have produced 12C-rich calcite and prominent baseline humps of unresolved complex mixtures (UCM), and 25-demethylated hopanes and tricyclic terpanes. The existence of sulfur-oxidizing bacteria and sulfate-reducing bacteria in the deposit may have resulted in bacterial sulfate reduction to sulfide, re-oxidization of the sulfide to sulfate and subsequent reduction of the sulfate to sulfide. This assertion is supported by ore-stage pyrite with δ34S values as low as-39.2‰, and the lightest sulfate (about 11‰) measured during the Phanerozoic, a difference of more than 46‰.     

Photocatalytic activity of TiO<Subscript>2</Subscript> sensitized by CdS quantum dots under visible-light irradiation

In this paper, CdS quantum dots sensitized TiO2 composite powders (QD-CdS/TiO2) were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern (XRD) shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD- CdS/TiO2 powder samples; the crystal size of CdS in QD- CdS/TiO2 is about 3-7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1∶2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B (RhB) is up to 92.2% within 60 min.     

含铜低温热轧取向硅钢初次再结晶组织研究

为研究含铜低温热轧取向硅钢再结晶组织,采用3种不同的初次再结晶退火工艺进行热处理.结果表明,脱碳退火前的高温退火工艺有助于增加硅钢初次再结晶组织中20°～45°晶界比率;采用渗氮工艺,可在大幅提高∑5晶界比率的同时增大晶粒尺寸.应用晶粒尺寸阈值公式计算出的初次晶粒大小约为8μm,计算结果与试验数据相符.     

多媒体教室设备故障快速反馈系统设计

利用VB语言开发出一套多媒体教室设备快速反馈系统,为上课教师和多媒体管理人员之间搭建了一个平台,实现了设备出现问题可以快速反馈到设备管理人员,经过使用,效果良好,达到设计目标。     

Regularization strategy for the Cauchy problem of Laplace’s equation from the viewpoint of regularization theory

Within the framework of the regularization theory, a spectral regularization method is introduced and analyzed. The convergence estimate under an appropriate choice of regularization parameter is obtained. A numerical implementation is described. Numerical examples show that the proposed method is effective and stable.     

渣油热接触改质反应机理——Ⅰ.不同热载体反立性能的考察

采用X光衍射、程序升温脱附、扫描电镜、微活性测试及表面结构测试等方法,对不同热载体的性能与结构进行了考察。结果表明,热载体是一种具有低比表面、低催化活性的情性物质,孔径范围大多在15～60nm,热载体的孔结构类似于平行壁的狭缝状毛细孔结构。用胜利常压渣油作原料,在固定流化床反应器中考察不同热载体的反应性能,发现热载体结构对反应结果有很大影响,同时,热载体还有较强的抗重金属的污染能力。     

渣油热接触改质反应机理——Ⅱ.胶质和沥青质的转化

以添加不同数量胶质或沥青质的胜利减二线为原料油,采用2~#热载体,在固定流化床反应装置上考察了胶质、沥青质的转化。结果表明,在通常的反应条件下,胶质大部分转化为液体,沥青质大部分转化为焦炭。采用热接触改质,可脱除渣油中40～60%的S、N,90%左右重金属Ni以及85%以上的残炭,约90%的胶质和近乎100%的沥青质。