16MnR钢超高周疲劳性能实验

用超声振动疲劳技术研究了16MnR钢的高周与超高周疲劳性能。实验在室温下进行,应力比R=-1,频率20kHz,采用狗骨形试样。试验获得了16MnR钢在10^5～10^9范围内的疲劳寿命曲线（S-N曲线）,结果发现曲线呈缓慢下降趋势,在10^7周次以后,试样仍未发生疲劳破坏,不存在传统意义上的疲劳极限。用电子扫描电镜对16MnR的高周和超高周疲劳断口进行了微观观测,结果发现,疲劳裂纹萌生于试样表面,未观察到含铁材料通常在超高周实验中出现的“鱼眼”现象。     

SN10-10型少油断路器更换为ZN30-10型真空开关理论分析

我局将重负荷的ＳＮ１０－１０Ⅱ型开关更换为ＺＮ３０－１０／１２５０型真空开关,原有开关柜及操动机构不变。由于ＳＮ１０－１０Ⅱ型少油开关触头接触方式为插入式,灭弧及绝缘介质为油,行程长,配ＣＤ１０－Ⅱ型磁操动机构,而ＺＮ３０－１０／１２５０型真空开关触头接触方式为对接式,行程短,配套操动机构为ＣＴ１７型弹簧机构。ＣＤ１０－Ⅱ型电磁操动机构操动力与ＺＮ３０－１０／１２５０型真空开关负载特性是否匹配,以及真空开关在分合过程中很容易产生过电压,而ＳＮ１０－１０型少油开关的过电压值与真空开关相比是很低的,因而产生了过电压抑制问题。文章从ＣＤ１０－Ⅱ型电磁操动机构,真空开关的负载特性,真空开关的过电压抑制、更换是否经济以及在更换过程中存在的问题等方面来论述。     

准双曲面齿轮的三次模糊设计法

本文用三次设计法对汽车主减速器准双曲面齿轮进行了多目标优化设计，对齿轮强度，传动平衡性，体积等目标运用模糊综合评判方法，不仅得到了最佳方案的参数，还得出了各参数的影响关系。     

镁合金搅拌摩擦焊接工艺参数优化

为了优化镁合金搅拌摩擦焊接工艺参数,对5 mm厚镁合金AZ31B板材的搅拌摩擦焊接技术进行了试验研究,利用SN比实验设计,对镁合金AZ31B搅拌摩擦焊接工艺参数进行了方差分析,优化了搅拌头的材料、结构,最终确定搅拌头的材料为W6Mo5Cr4V2,结构为凹面圆台形.轴肩尺寸为12 mm.探针的根部直径为5.5 mm,端部直径为2.5 mm,长度为4.7 mm.获得镁合金AZ31B搅拌摩擦焊的工艺参数显著性顺序为旋转速度、横向速度和压力;确定了镁合金AZ31B搅拌摩擦焊的最优工艺参数为1500 r/min、47.5 mm/min、3kN.     

On solidification shrinkage of copper–lead and copper–tin–lead alloys

Abstract

Solidification shrinkage is an important concept in achieving sound castings. In the present work solidification shrinkage was studied in copper–lead and copper–lead–tin alloys. A series of solidification experiments was performed under different cooling rates using a dilatometer which was developed for melting and solidification purposes. The volume change was measured during primary solidification and the monotectic reaction. In order to explain the volume-changing results, the sample macrostructures were studied to evaluate gas and shrinkage cavities which were formed during the solidification. Furthermore, the volume fraction of the primary phase during solidification was evaluated in the samples that were quenched from different temperatures below the liquidus temperature. A shrinkage model was used to explain the volume changes during solidification.     

基于首次碰撞源方法的多维SN射线效应研究

通过半解析法求解由孤立点源产生的未碰撞中子源项,进而求出首次碰撞源分布,以将孤立的源分布到更广的范围中,从而减轻由离散纵标法计算产生的射线效应。编制了适应于三维离散纵标计算程序CTDOS的射线效应减轻程序REM3D,与Kobayashi三维基准题的结果进行比对,证明了射线效应减弱的正确性与本程序的可行性。     

COSINE软件包组件参数计算程序LATC中SN输运模块的开发与初步验证

本文论述了组件参数计算程序LATC的离散纵标（S_N）输运模块的理论模型。通过对基准问题的校验,验证了自主开发的组件参数计算程序LATC中基于一维、二维S_N理论及扩散综合加速收敛方法的输运模块。结果表明,LATC组件参数计算程序的S_N输运模块与基准解吻合良好,初步验证了LATC组件参数计算程序的S_N输运模块的正确性。     

SN2D程序在C5G7基准例题上的验证与分析

C5G7基准例题因其具有强烈非均匀性、组件能谱差异大等特点,常用来检验软件计算有效性。在对栅元进行不同的几何等效和对原有的栅元等效均匀化方法进行改进的情况下,采用二维离散纵标法输运计算程序SN2D对C5G7基准例题进行了分析计算,给出了各种计算条件下k_eff和功率分布的计算误差。结果表明,SN2D程序可应用于C5G7基准例题的求解。计算结果可为求解类似问题时计算程序及条件的选择提供直接参考。     

Novel,Stereoselective and Stereospecific Synthesis of Allenylphosphonates and Related Compounds via Palladium‐Catalyzed Propargylic Substitution

We have developed a novel method for the synthesis of allenylphosphonates and related compounds based on a palladium(0)‐catalyzed reaction of propargylic derivatives with H‐phosphonate, H‐phosphonothioate, H‐phosphonoselenoate, and H‐phosphinate esters. The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center. Some mechanistic aspects of this new reaction were also investigated.     

Development of New Solid Angle Quadrature Sets to Satisfy Even- and Odd-Moment Conditions

In this paper, we propose new solid angle quadrature sets named EON for the SN method. The EON quadrature sets are developed for the 3-D xyz geometry, and satisfy not only even-moment conditions but also odd-moment conditions for direction cosines over an octant of the sphere. We can accurately calculate the numerical integration of the polynomial of direction cosines using EON. We verify the effectiveness of EON through the 2-D bulk shield problem and the 3-D neutron transport benchmark problems. The verification results indicate that the angular discretization error of EON is much smaller than that of the conventional level symmetric quadrature set.