隧洞岩爆机理与岩爆预测的断裂力学分析

在应用断裂力学原理分析岩体裂隙扩展特点的基础上, 分析讨论了岩爆发生机理, 提出了隧道围岩应力强度因子等值线的概念, 认为隧洞岩爆将沿该应力强度因子等值线 ＫⅡθ＝ ＫⅡＣ圈定的范围崩落, 岩体裂隙失稳扩展导致隧洞岩爆的必要条件为同时满足裂纹开裂判据 ＫⅡ＝ ＫⅡＣ及裂纹失稳扩展判据ｋ ＋ ｆ′（δ） ＜ ０ , 并指出同时满足这两个条件的岩体裂隙有临界开裂和临界止裂两个长度。     

泥沙起动条件及机理的非线性研究

 分析了单颗粒、均匀沙及非均匀沙的起动现象及其机理，认为泥沙的起动属于突变论研究的范畴。从泥沙起动所遵循起动条件的力学规律出发，导出泥沙起动条件方程。在此基础上，利用尖点突变性质对各种泥沙起动现象及机理进行了描述和说明。     

法国拉克、麦隆气田对安岳气田龙王庙组气藏开发的启示

四川盆地安岳气田磨溪区块下寒武统龙王庙组气藏是我国近年发现的一个特大型整装复杂碳酸盐岩气藏,该气藏具有储层孔隙度低、裂缝孔洞发育、气水关系复杂、中含硫化氢、气井单井产量高和储量规模大等特点,国内尚无类似气藏开发先例可资借鉴。为此,基于CC和IHS数据库,通过多指标的对比分析,筛选出法国的拉克和麦隆两个相似气田并进行了开发规律剖析,同时结合大量相关数据统计分析,形成了该类气藏在战略定位、前期评价、开发技术政策制定、动态分析和风险管理策略方面的6点经验启示:①大型主力气藏保护性开发,适当降低采气速度可以确保长期安全稳定生产;②试采周期越长,对气藏特征的认识越清楚,可为高效开发打下坚实的基础;③多种方法量化描述裂缝,综合评价裂缝对气田开发的影响;④依据气藏特点,确定合理的单井配产;⑤生产井集中部署在构造高部位,射孔层位尽量远离气水界面,部署观察井监测水体动态;⑥高度重视储量风险评估,采取滚动勘探开发和弹性指标策略降低开发风险。上述经验启示对于龙王庙组及类似气藏的高效开发具有指导作用。     

氮素水平对不同穗型水稻品种植株衰老和产量的影响

在大田条件下,研究了两种氮素水平对直、弯穗水稻品种植株生长、叶片衰老和产量的影响。结果表明,高氮条件下两品种的朱粗度和叶片性状均优于低氮条件。增施氮肥能提高剑叶的叶绿素含量,延长叶绿素含量缓降期,使植株在生育后期能保持较高的绿叶面积;同时能提高剑叶的全氮含量,延长光合速率高值持续期,增加植株的干物质积累和籽粒产量。在同一氮素水平下,直立穗型品种的植株粗度、剑叶活力、籽粒灌浆速率、千粒重、生物产量及籽粒产量均略优于弯曲穗型品种。     

Na2ZrF6-KoH中微弧氧化2024铝合金陶瓷膜

为了提高2024铝合金的表面硬度和耐磨损性能,采用微弧氧化法在Na2zrF6-KOH溶液中使2024铝合金表面形成氧化物陶瓷膜.分别用扫描电镜、电子探针及X射线衍射研究了陶瓷膜的组织形貌、元素分布和相组成.结果表明随氧化时间的增加,阴阳极电压逐渐增加,且阴极电压低于阳极电压;厚约20μm的膜可分为致密层与琉松层;相对致密均匀的膜层主要由α-Al2O3,γ-Al2O3和少量的非晶相物质组成电解液所含元素zr,进入到膜层中,表明电解液组元剧烈参与微弧氧化反应;陶瓷膜的平均硬度约为16 GPa,分布在距界面10μm附近.     

Concept design of CFETR superconducting magnet system based on different maintenance ports

CFETR which stands for “China Fusion Engineering Test Reactor” is a new tokamak device. Its magnet system includes the Toroidal Field (TF) winding, Center solenoid winding (CS) and Poloidal Field (PF) winding. The main goal of the project is to build a fusion engineering Tokamak reactor with its fusion power is 50–200 MW and should be self-sufficiency by blanket.In order to ensure the maintenance ports design and maintenance method, this article discussed the concept design of the magnet system based on different maintenance port cases. The paper detailed studied the magnet system of CFETR including the electromagnetic analysis and parameters for TF (CS)PF. Besides, the volt-seconds of ohmic field are presented as detailed as possible in this paper. In addition, the calculations and optimizations of equilibrium field which should guarantee the plasma discharge of single null shape is carried out. The design work reported here illustrates that the present maintenance ports will not have a great impact on the design of the magnet system. The concept design of the magnet system can meet the requirement of the physical target.     

连续式低压铸造技术的研究与开发

传统的低压铸造方法存在效率低、无法连续生产、金属液品质及气压加压压力波动大的缺陷,为此开发出一种基于PLC和触摸屏技术的新型连续式低压铸造技术.该技术将现有传统的低压浇注兼保温坩埚分成3个独立的坩埚即保温坩埚、加压坩埚、浇注坩埚,3个坩埚底部由过道连通,分别完成加、补料、液面加压及升液浇注3个主要动作.加压坩埚具有定量功能,每次浇注前液面均保持在恒定高度,加压时升液曲线稳定、精确,重复性高.保温坩埚实现了外部补料与加压浇注互不干涉,保证了生产的连续性,生产效率显著提高.     

SPS快速烧结制备纳米结构Ti5Si3-TiC复合材料

采用金属钛和碳化硅为初始原料,采用放电等离子体快速烧结(SPS)技术制备了致密纳米结构的Ti5Si3-TiC复合材料.借助XRD、SEM和TEM考察了复合材料的相组成和显微结构,利用压痕法测定了其室温显微硬度和断裂韧性.结果表明利用SPS技术可在1260℃,保温8 min条件下使金属钛和碳化硅同步完成反应、烧结、致密化,生成Ti5Si3-TiC复合材料,并且晶粒细小,其中TiC晶粒尺寸＜200nm.     

碳纳米管复合二维碳化钛负载钯粒子电催化性能研究

为提高Ti₃C₂的层间距及电催化性能, 利用碳纳米管(CNT)进行层间微结构调控。Ti₃AlC₂经HF化学刻蚀法获得层状Ti₃C₂, 再以羟基化碳纳米管(CNT)以及次氯钯酸钾(K₂PdCl₄)为原料, 通过超声分散和溶剂热法将贵金属Pd粒子负载到Ti₃C₂-CNT上, 制得直接甲醇电池阳极催化剂材料Pd/Ti₃C₂-CNT。采用X射线衍射、扫描电镜以及光电子衍射对样品的形貌和结构进行表征, 考察了CNT对Ti₃C₂层间微结构的调整效果; 采用循环伏安法、计时电流法以及交流阻抗图谱研究了Pd/Ti₃C₂-CNT复合催化剂在酸性、碱性溶液中对甲酸、甲醇的电催化性能。结果表明, 复合材料中CNT对Ti₃C₂有插层作用, 建立了“桥联”效果, 有利于催化剂载体电子传输, 进而提高了Pd/Ti₃C₂-CNT的电催化性能。     

Opportunistic Space-Division Multiple Access With Beam Selection

In this paper, a novel transmission technique for the multiple-input multiple-output (MIMO) broadcast channel is proposed that allows simultaneous transmission to multiple users with limited feedback from each user. During a training phase, the base station modulates a training sequence on multiple sets of randomly chosen orthogonal beamforming vectors. Each user sends the index of the best beamforming vector and the corresponding signal-to-interference-plus-noise ratio for that set of orthogonal vectors back to the base station. The base station opportunistically determines the users and corresponding orthogonal vectors that maximize the sum capacity. Based on the capacity expressions, the optimal amount of training to maximize the sum capacity is derived as a function of the system parameters. The main advantage of the proposed system is that it provides throughput gains for the MIMO broadcast channel with a small feedback overhead, and provides these gains even with a small number of active users. Numerical simulations show that a 20% gain in sum capacity is achieved (for a small number of users) over conventional opportunistic space division multiple access, and a 100% gain (for a large number of users) over conventional opportunistic beamforming when the number of transmit antennas is four.