基于离散裂缝模型的页岩气动态特征分析

页岩储层孔隙结构复杂,基质渗透率低,天然裂缝发育,水平井体积压裂为其主要生产手段,表现出以裂缝系统裂缝渗流为主,基质系统扩散流、滑脱流以及吸附-解吸附现象共同作用的多尺度流动特点。基于离散裂缝建立页岩气渗流数学模型,利用有限元分析方法进行数值求解,通过实例研究分析页岩气生产动态特征,以及开发过程中压裂级数和裂缝半长对储层压力分布和页岩气井生产动态特征的影响。结果表明:页岩气井初期产量高,但递减快,生产周期长;开发初期以裂缝渗流为主,压裂级数起主导作用,级数越多,压力波传播越快,储层压力下降明显,产能主要集中在生产初期;开发后期以基质渗流为主,裂缝半长作用增强,产量递减率下降,生产井附近压力接近废弃压力,生产能力下降。     

正偏置式凸轮转子叶片泵的最佳参数

通过对ＴＹＢ-Ｅ６３型正偏置式凸轮转子叶片泵的受力情况和磨损状况的深入分析,优化出最佳的结构参数和动力参数．理论分析和试验结果表明：与普通凸轮转子叶片泵相比,采用最佳结构参数和动力参数的正偏置式凸轮转子叶片泵能进一步减少磨损、提高寿命、降低流量脉动和噪声．     

Structural basis for recognition of centromere histone variant CenH3 by the chaperone Scm3

The centromere is a unique chromosomal locus that ensures accurate segregation of chromosomes during cell division by directing the assembly of a multiprotein complex, the kinetochore. The centromere is marked by a conserved variant of conventional histone H3 termed CenH3 or CENP-A (ref. 2). A conserved motif of CenH3, the CATD, defined by loop 1 and helix 2 of the histone fold, is necessary and sufficient for specifying centromere functions of CenH3 (refs 3, 4). The structural basis of this specification is of particular interest. Yeast Scm3 and human HJURP are conserved non-histone proteins that interact physically with the (CenH3-H4)(2) heterotetramer and are required for the deposition of CenH3 at centromeres in vivo. Here we have elucidated the structural basis for recognition of budding yeast (Saccharomyces cerevisiae) CenH3 (called Cse4) by Scm3. We solved the structure of the Cse4-binding domain (CBD) of Scm3 in complex with Cse4 and H4 in a single chain model. An α-helix and an irregular loop at the conserved amino terminus and a shorter α-helix at the carboxy terminus of Scm3(CBD) wraps around the Cse4-H4 dimer. Four Cse4-specific residues in the N-terminal region of helix 2 are sufficient for specific recognition by conserved and functionally important residues in the N-terminal helix of Scm3 through formation of a hydrophobic cluster. Scm3(CBD) induces major conformational changes and sterically occludes DNA-binding sites in the structure of Cse4 and H4. These findings have implications for the assembly and architecture of the centromeric nucleosome.     

A new method to calculate the productivity index for vertical fractured well of tight gas reservoir

Generally the irreducible water saturation of low permeability gas reservoir is quite high which leads to the permeability stress sensibility and threshold pressure gradient. Under the assumption that permeability varies with experimental law of the pseudo pressure drop, according to concepts of perturbable ellipses and equivalent developing regulations, the calculation method of stable production of hydraulically fractured gas well in low permeability reservoirs is investigated with threshold pressure. And productivity curve is drawn and analyzed. The result shows that, permeability modulus and threshold pressure have effect on production of fractured gas well. The higher the permeability modulus and the threshold pressure, the lower the production is. Therefore, the impact of stress sensitive and threshold pressure must he considered when analyzing the productivity of vertical fracture well in low permeability gas reservoir.     

螺旋提升循环式谷物烘干机的研制

通过大量实验及理论计算研制出新型的谷物烘干机，该机的研制应用了先进的间歇式干燥理论，实现了谷物在烘干过程中的缓苏，实验数据说明该机具有优质、高效的加工特点，满足各种谷物烘干的要求，非常适合我国广大农村联产承包责任制的生产方式。     

胜二区沙二3封堵大孔道方案优化设计

在油藏数值模拟基础上，建立了胜二区沙二３封堵大孔道方案优化设计的数学模型，计算了该区块封堵大孔道优化方案。优化方案实施结果表明，该区块含水上升速度得到了有效控制。增加了产油量，取得了好的经济效益。     

Pd/C催化氢化高效脱除含氮糖中的苄基型保护基

通过抽真空脱除Pd/C催化剂表面吸附的有害气体以及利用高纯氮气对反应体系进行脱气,本实验方法能够高效脱除苄基保护的N-取代fagomine衍生物的保护基,而且哌啶环N-苄基型取代基也可以被脱去.其中,N-非苄基型取代fagomine衍生物的脱保护反应的收率为94%～98%.所有化合物的结构均经质谱和核磁共振谱确证.     

水驱优势通道下微观潜力分布及改变流线挖潜

根据中高渗油藏优势通道孔喉分布特征,建立了具有不同优势通道发育规模的二维刻蚀模型,对优势通道下剩余油微观分布及演变特征进行了研究;通过分析不同改变流线动用方法适应性,初步揭示了优势通道下剩余油改变流线动用机制;结合油藏数值模拟,量化了改变流线动用策略。结果表明,提高驱替速度可使弱优势通道下剩余油大幅降低,而强优势通道变化较小;根据优势通道下剩余油赋存形态、形成机制,将其分成了4类,即死角式、并联式、包围式、绕流式,其中前两类受优势通道规模、驱替速度影响极小,而后两类仅在优势通道规模较小时,才会随驱替速度增加而大幅减小。应以利用与克服优势通道的角度去设计流线动用改变方式,在流线动用方式合理改变时,强优势通道注采比应适当降低,而弱优势通道相反。     

仿真在光学课程教学中的应用

光学课程中涉及大量的光学系统计算,计算机仿真在光学系统的像差计算、成像系统光束传输计算等方面具有重要的应用。文章结合研究生课程《工程光学》和《光学系统CAD》教学经验,利用Matlab,C ,对激光束准直的非球面光学系统以及光子晶体Bragg光纤结构进行了计算机仿真,对培养研究生进行计算机仿真优化设计具有积极的参考意义。     

广义Loeb测度及像Loeb测度的性质

广义Ｌｏｅｂ测度及像Ｌｏｅｂ测度的性质陈东立１冯汉桥２（１西安建筑科技大学基础课部，西安７１００５５；２陕西师范大学计算机科学系，西安７１００６２；第一作者，男，３２岁，讲师）１广义Ｌｏｅｂ测度设（Ｙ，Ａ，ν）为一个内的有限可加测度空间，即（Ｙ，Ａ，...