Matter-wave interference in an axial triple-well optical dipole trap

This paper proposes a scheme of axial triple-well optical dipole trap by employing a simple optical system composed of a circular cosine grating and a lens. Three optical wells separated averagely by ～37 μm were created when illuminating by a YAG laser with power 1 mW. These wells with average trapping depth ～0.5 μK and volume ～74 μm³ are suitable to trap and manipulate an atomic Bose--Einstein condensation (BEC). Due to a controllable grating implemented by a spatial light modulator, an evolution between a triple-well trap and a single-well one is achievable by adjusting the height of potential barrier between adjacent wells. Based on this novel triple-well potentials, the loading and splitting of BEC, as well as the interference between three freely expanding BECs, are also numerically stimulated within the framework of mean-field treatment. By fitting three cosine functions with three Gaussian envelopes to interference fringe, the information of relative phases among three condensates is extracted.     

雨生红球藻中crtO基因存在3个5’上游侧翼序列

在本研究中,我们首次通过基因组上游第一次步移克隆到了雨生红球藻中crtO基因的3个不同大小的5’上游侧翼序列1．1kb,1．9kb和2．2kb。利用生物信息学方法分别预测并比较了这3个不同大小的5’上游侧翼序列,结果发现,三者具有与高等植物相类似的顺式作用元件,如脱落酸反应元件（ABRE）、干燥或低温反应元件（DRE／C-repeat）、几种光反应元件（G1-box,GAG-motif,l-boxand ATC—motif）、热激反应元件（HSE）、机械伤害反应元件（WUN-motif）、生长素反应元件（TGA-element）、茉莉酸甲酯反应元件（TGACG-element）和反式作用因子MYB蛋白的结合位点（MBSandMRE）等等,但是三者并不具有典型的TATA框和CCAAT框。上述研究预示了雨生红球藻虾青素合成中crtO基因调控方式的多样化。     

Study of A Geo-Acoustic Model of Gas-Bearing Sediment and Its Application in Sediment with Low Acoustic Velocity

A new geo-acoustic model for gas-bearing sediment is proposed based on the work of Dvorkin and Prasad, and Biot theory. Only five geophysical parameters: sediment mineral composition, free gas saturation, tortuosity (also known as the structure factor), permeability, and porosity, are considered in the model. A benefit of this model is that we need only five parameters instead of ten parameters in the Biot’s formulas for acoustic velocity and attenuation calculation. Here the model is demonstrated with the in-situ experimental data collected from the Hangzhou Bay, China. The results of this study suggest that free gas content in sediment is the most critical condition resulting in a low acoustic velocity (compressional wave). The respective contributions of the other four parameters in the model are also discussed.     

致密砂岩储层渗透率预测技术研究进展

对于致密砂岩储层而言,渗透率是评价储层物性、渗流特征的重要参数,也是储层产能挖潜和提高采收率的关键.致密砂岩储层孔隙类型多样,孔隙结构复杂,非均质性强,孔渗关系变化复杂,并非简单的线性关系.利用孔渗统计回归和测井解释方法预测精度较低,致密砂岩储层渗透率预测成为一项重要而艰巨的任务.本研究基于孔喉结构是致密砂岩储层渗透率的主控因素,重点利用毛管压力(MICP)、核磁共振(NMR)、岩心物性实验数据及测井资料,对基于统计回归理论、流体流动单元划分(FZI)储层分类理论、分形几何理论及人工智能理论的渗透率预测方法进行综述.最后指出,基于MICP、NMR及常规测井,将流体流动单元划分(FZI)储层分类技术、分形几何数字岩心技术以及人工智能机器学习技术相结合,可形成一套具有岩石物理学意义的致密砂岩储层渗透率评价和预测的有效方法.     

硬岩PDC定向钻头优化设计及其表面增材技术研究

定向长钻孔是煤矿瓦斯、水害治理的主要技术手段,PDC定向钻头性能是影响坚硬地层钻进效率的重要因素。针对煤层顶底板岩层定向长钻孔施工中出现因PDC钻头体断翼、PDC崩齿等问题导致的频繁起下钻、施工效率低等现象,采用等切削布齿原则对刀翼布齿进行优化,有效降低切削齿冲击破坏;通过流体力学仿真分析,优化钻头水力参数,保证岩屑及时排出孔底,防止切削齿因重复破碎岩石导致过早损坏;通过仿真分析,优选大直径PDC异型齿,提高切削齿耐磨和抗冲击性能;引入表面增材制造技术,通过优化等离子(PTA)增材制造工艺参数,实现了兼具胎体耐磨耐冲蚀和钢体强韧性的WC基复合钻头体加工工艺。新研制的PDC定向钻头,在淮南顾桥煤矿北区底板探放水钻孔中进行了现场试验。结果表明：钻进致密、坚硬灰岩地层时,2只钻头寿命分别达到827、810 m,相对于以前的?120 mm胎体式定向钻头平均寿命300 m有较大幅度的提高,并降低了上下钻等辅助作业时间,提高了施工效率,达到了硬岩定向长钻孔提速增效的目标,为硬岩定向长钻孔用PDC钻头设计和制造工艺开发提供了新的解决方案。     

“北斗+5G将改变世界和时代”——听院士专家谈北斗、话5G、畅想未来

当5G遇上北斗,会怎么样?有观点说,“取决于人们的想象力”. 2020年,两个“国之重器”相遇了.这一年,北斗三号卫星导航系统完成全球组网,并向全球提供服务;这一年,5G(第五代移动通信)在我国开启大规模商用.可谓是“在对的时间里遇到对的你”,北斗和5G“一见面”便成为一对“好朋友”. 人们期盼着北斗和5G能更快地成长...     

Time domain method for calculating free field motion of a layered half-space subjected to obliquely incident body waves

In numerical simulation of wave scattering under oblique incident body waves using the finite element method, the free field motion at the incident lateral boundary induced by the background layered half-space complicates the computational area. In order to replace the complex frequency domain method, a time-domain method to calculate the free field motion of a layered half-space subjected to oblique incident body waves is developed in this paper. The new method decouples the equations of motion used in the finite element method and offers an interpolation formula of the free field motion. This formula is based on the fact that the apparent horizontal velocity of the free field motion is constant and can be calculated exactly. Both the theoretical analysis and numerical results demonstrate that the proposed method offers a high degree of accuracy.     

熊耳群的金矿控矿构造及其大地构造背景

熊耳群目前已成为一重要的含金地层，金矿床类型多样，包括构造蚀变岩型、煤破角砾岩型、石英脉型和铅－金矿型，各种类型金矿床均与构造有密切关系。