小井距开发现河油田低渗油藏可行性研究

认为注采井网井距大,水驱控制程度差,采收率偏低是影响胜利油田现河低渗透油藏开发的关键,通过井间密度与水驱控制程度和采收率的关系等分析,提出了现河低渗透油藏开发的合理的井网密度。     

45号钢二次枝晶臂间距与冷却速度的关系

本文利用可控平均冷却速度的单向凝固实验炉测定了４５号钢在不同平均冷却速度下的冷却曲线，由此得到其在凝固期间的平均冷却速度Ｒ，相应地测量了不同平均冷却速度下试样的二次枝晶臂间距Ｓ２，通过回归，得到了如下关系式：Ｓ２＝７２７Ｒ－０．４１，并将引式成功地应用于实际生产中。     

Effects of circumferential pick spacing on boom type roadheader cutting head performance

Effects of equal and unequal circumferential pick spacing on the performance of boom type roadheaders having cylindrical cutting heads are investigated. For this purpose, two experimental cutting heads with equal and unequal circumferential spacing are designed and manufactured. The cutting head with unequal circumferential spacing is specifically designed to prevent tool-holder overlap at the nose section. Manufacturing difficulties associated with equal circumferential pick spacing due to tool-holder overlap are discussed with solid modeling and practical applications. The heads are tested at Park Cayirhan Coal Mine in Turkey and their cutting performances are analysed. Although better cutting performance for equal circumferential spacing are predicted by force–balance analysis, in situ measurements of instantaneous (net) traversing speed and cutting rate, pick consumption rate and machine vibration show that no significant difference exists between the performances of the two cutting heads.     

Effect of lamellar spacing on microstructural instability and creep behavior of a lamellar TiAl alloy

Finer lamellar spacing in the lamellar structure of a Ti–45Al–2Nb–2Mn + 0.8 vol.%TiB₂ (45XD) alloy does improve the primary creep resistance. However, the unstable nature of the fine plate contributes largely to the degradation of the lamellar structure and a rapid increase in the tertiary creep rate, indicating that a fine lamellar structure has a detrimental effect on the long-term creep.     

交叉极化天线阵列信道的相关性

针对符合多簇拉普拉斯分布的功率角度谱,推导了适用于均匀线阵和均匀圆阵信道相关性的闭式表达式. 该表达式反映了信道角度功率谱以及交叉极化鉴别率对信道相关性的影响. 比较了具有相同角度扩展的单簇与多簇拉普拉斯角度功率谱引入信道相关性的差异. 分析了簇内角度扩展不同时,天线阵列信道相关性随均匀线阵天线间距或均匀圆阵半径的变化. 给出了簇内平均角和簇内角度扩展分别取不同值时,信道交叉极化鉴别率对应的等效天线间距.     

近距多座并行桥梁墩前壅水研究

为了研究近距多座并行桥梁的壅水规律,在分析了单座桥梁的壅水规律后,类比应用到两座并行桥梁壅水的研究中且得到相应的规律,然后基于这些成果可达到研究目的。研究结果表明,如果被动影响桥梁位于主动影响桥梁的下游,则主动影响桥梁的壅水除了受自身阻水影响外,还要附加上被动影响桥梁的壅水对其带来的正影响作用;反之,则会受到被动影响桥梁的壅水对其带来的负影响,且影响系数都会随着两桥的桥间距增大而减小。假设并行桥梁的壅水仅仅两两影响时会形成修正壅水,且该修正壅水对其它桥梁产生重复的二次影响后会无限接近真实壅水。在这个前提下,总结出多桥并行时各桥壅水的经验公式。     

Bi对Al-30% Mg_2Si复合材料组织和性能的影响

为了研究铋(Bi)对Al-30%Mg2Si复合材料显微组织和力学性能的影响,利用原位内生工艺制备了Al-30%Mg2Si复合材料,并加入不同量的Bi对其细化变质.利用扫描电镜进行显微组织观察,并利用布氏硬度计和液压式万能试验机进行力学性能测试.试验结果显示,稀土Bi的质量分数由0%增加至5%时,初生相Mg2Si的平均晶粒尺寸先减小后变大,而抗拉强度、硬度和伸长率则先提高后减小;当Bi加入量约为3%时,初生相Mg2Si显微组织细化效果最为明显,综合力学性能最好.     

液相流动对柱晶一次间距的影响

利用带有对流驱动系统的定向凝固装置,研究了液相稳定流动时透明合金SCN-2wt-％Ace定向凝固的动态过程.结果表明:流动显著改变定向凝固柱状晶的一次间距枝晶的间距增大,主要是流动与枝端浓度场耦合作用的结果;胞晶的间距变小,主要是侧向分枝转向生长的结果     

Effect of strontium on columnar growth of dendritic α phase in near-eutectic Al-11.6%Si alloys

For Al-11.6 % Si alloy, the influence of the addition of Sr on the morphology of the dendrite α phase was investigated, and the characteristic parameters of the dendrite α phase, the primary dendrite spacing and the secondary dendrite arm spacing, were also measured. The addition of strontium promotes the columnar dendrite growth and leads to a decrease of both the primary dendrite spacing and secondary dendrite arm spacing with the increase of the content of strontium in the modified near-eutectic Al-Si alloys. It is thought that the addition of Sr leads to a reduction of the solid-liquid interfacial energy of the dendrite α phase, consequently resulting in a decrease of the growth undercooling of dendrite tips. And hence, the nucleation of the equiaxed grains in the liquid in front of the columnar dendrite tips is restrained, thus the addition of strontium in Al-Si alloys promotes the growth of the columnar dendrites. The reduction of the solid-liquid interfacial energy also leads to the decreases in the primary dendrite spacing and the secondary dendrite arm spacing.     

枝晶间距对镍基单晶合金蠕变性能的影响

为了研究枝晶间距对镍基单晶合金组织与蠕变性能的影响,采用不同抽拉速率制备出两种不同枝晶间距的单晶镍基合金.通过蠕变性能测试及组织形貌观察,研究了枝晶间距对合金成分偏析及蠕变性能的影响.结果表明,随着合金枝晶间距的减小,元素成分偏析程度降低,且在相同热处理条件下,枝晶间距较小的合金具有较好的蠕变性能.合金在稳态蠕变期间的变形机制是位错攀移越过筏状γ′相,而蠕变后期的变形机制是位错在基体中滑移和切入筏状γ′相.蠕变断裂后,在试样不同区域筏状γ′相具有不同的形貌,在远离断口区域,筏状γ′相与应力轴方向垂直,而在近断口区域,筏状γ′相尺寸及扭曲程度均增加.