立方相GaN的持续光电导

研究了金属有机物化学气相外延 (MOVPE)方法生长的非故意掺杂的立方相 Ga N的持续光电导效应 .在六方相 Ga N中普遍认为持续光电导效应与黄光发射有关 ,而实验则显示在立方 Ga N中 ,持续光电导效应与其中的六方相 Ga N夹杂有关系 ,而与黄光发射没有关系 .文中提出 ,立方相 Ga N与其中的六方相 Ga N夹杂之间的势垒引起的空间载流子分离是导致持续光电导现象的物理原因 .通过建立势垒限制复合模型 ,解释了立方相 Ga N的持续光电导现象的物理过程 ,并对光电导衰减过程的动力学作了分析 .对实验数据拟合的结果证明以上的模型和推导是与实验相符的 .     

Fissure evolution and evaluation of pressure-relief gas drainage in the exploitation of super-remote protected seams

Based on nonlinearity contact theory and the geological structure of the Xieqiao Coal Mine in the newly developed Huainan coal field, rock movements, mining fissures and deformation of overlying strata were simulated by using the interface unit of FLAC3D to evaluate the pressure-relief gas drainage in the exploitation of super-remote protected seams. The simulation indicates that the height of the water flowing fractured zone is 54 m in the overlying strata above the protective layer. The maximum relative swelling deformation of the C 13 coal seam is 0.232%,while the mining height is 3.0 m and the distance from the B8 roof to the C13 floor is 129 m, which provides good agreement with a similar experiment and in situ results. The feasibility of exploitation of a super-remote protective coal seam and the performance of the pressure-relief gas drainage in a super-remote protected layer are evaluated by comparisons with practice projects. It demonstrates that the relieved gas in the super-remote protected layers could be better drained and it is feasible to exploit the B8 coal seam before the C13 super-remote protected coal seam. The method is applicable for the study of rock movements, mining fissures and deformation of the overburden, using the interface unit to analyze the contact problems in coal mines.     

Similarity model tests of movement and deformation of coal-rock mass below stopes

For a study of the movement and deformation of coal-rock mass and low protected seams below a stope,as well as for fracture developments and rules of evolution of permeability,we designed a plane strain model test stand to carry out model tests of similar materials in order to improve the effect of gas drainage from low protected seams and to measure the movement and deformation of coal-rock mass using a method of non-contact close-range photogrammetry.Our results show that 1) using paraffin melting to take the place of coal seam mining can satisfy the mining conditions of a protective seam;2) coal-rock mass under goafs has an upward movement after the protective seam has been mined,causing floor heaving;3) low protected seams become swollen and deformed,providing a good pressure-relief effect and causing the coal-rock mass under both sides of coal pillars to become deformed by compression and 4) the evolution of permeability of low protected seams follows the way of initial values→a slight decrease→a great increase→stability→final decrease.Simultaneously,the coefficient of air permeability increased at a decreasing rate with an increase in interlayer spacing.     

MODELLING OF P/M FORMING PROCESSES BY FEM

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武汉轨道交通2号线岩溶地段隧道工法研究

武汉地铁2号线虎泉站-光谷广场站区间隧道沿线灰岩分布广泛,岩溶发育,采取钻探、物探等综合勘探技术,查明了岩溶分布特性。在区间隧道施工前,进行了溶洞注浆加固处理;并在此基础上,对区间隧道矿山法、盾构法以及明挖法等工法进行了综合比较,提出了适应本地层条件下的矿山法施工方案,达到了预期的效果,可为类似工程的设计和施工提供借鉴。     

浅析嵩山-侯家倒转背斜西翼“永平式”铜硫矿床

永平铜硫矿床位于嵩山-侯家倒转背斜的东翼,虽然矿化与矽卡岩化关系密切,成矿地质条件和成矿模式等都有别于一般的矽卡岩型矿床。鉴于矿床类型比较独特,专家和业内人士将矿床冠名为“永平式”铜硫矿床。嵩山-侯家倒转背斜的西翼,与永平铜硫矿床相比,具有相似的成矿地质环境,是寻找“永平式”铜硫矿床的重要“靶区”,找矿前景良好。     

一种基于模糊概率推理和遗传算法相结合的变压器故障诊断研究

在概率因果推理模型的基础上,引入模糊理论,重新建立了模糊概率因果变压器故障诊断模型,并从非线性组合优化的角度提出了该模型的GA求解策略。这对较快、较准确地搜索变压器故障提供了一种新的思路。实验数据表明:该文提出的新方法同时提高了并发性故障和单故障的识别率。     

聚合物-水泥基注浆材料早期流变及水化特性

为制备满足复杂地层加固工程需求的高性能水泥基注浆材料,探究以偏铝酸钠(SA)、聚羧酸(Sp)及高吸水性树脂(SAP)为组分的聚合物体系及其掺量对新拌水泥浆体流变特性与泌水率的影响,并采用水化放热监测与倒置荧光显微技术,对不同体系下水泥浆体早期水化进程及微米级颗粒的悬浮分散形态进行分析.结果表明:新拌水泥浆液流动性和泌水率与SA、SAP掺量呈负相关,随Sp掺量增加而提高. Sp及SAP延缓了水泥早期水化进程,改性样延迟近1 h进入水化诱导期,诱导期内水化放热速率显著降低.在不同掺量SA的促凝效应、Sp的分散效应以及SAP的"水库"作用下,新拌水泥浆液表现为初始及经时流动度大于200 mm的高流态期可分别被控制在10、20、30 min内且析水率小于5%(稳定性浆液),接近临界期时流动度陡降、流变参数突增并迅速凝结的流变特性.结合微观结构观测结果,建立了新拌水泥浆体流变演化模型,揭示多聚合物协调效应下水泥浆体呈现分散-储水-流变-水化的早期流变机制.     

RBD从理论走向实践的困境与出路

RBD作为城市游憩系统中的重要组成部分,在我国城市转型中发挥着重要作用,但在RBD从理论走向实践应用的过程中,RBD面临理论与规划实践脱节、可操作性不强等一系列问题。为推动RBD理论与规划实践的发展,应加强RBD理论研究,构建系统完整的RBD规划内容体系;以RBD理论为指导,增强RBD规划的科学性和可操作性。     

基于更新补偿的实化视图增量过滤研究

针对WHIPS实化视图维护模型不能检测无效增量问题,提出了增量过滤机制.该机制利用视图定义中的约束条件,并通过更新补偿机制,对基表增量进行有效性检测和过滤,减少了网络通信并避免了数据仓库端的无效的视图增量计算.文章最后通过实验对比,证明了这种机制的有效性.