求解半无限长多孔介质柱体水动力弥散系数的一种最小二乘法

针对半无限长多孔介质柱体,一端为定浓度边界的水动力弥散反求参数问题,先用数值方法求解补余误差函数erfc（x）的反函数,再根据该问题的解析解,通过变量代换,构造一个基于解析解的最小二乘模型来反求水动力弥散系数。最后将该方法应用于一个实例,计算结果表明该方法比erfc（x）近似公式法、配线法、正态分布函数法等传统方法要好。     

南海毛蚶形态特征对体重的相关分析

随机选取同龄南海毛蚶Scapharca subcrenata雌性62只、雄性59只,测量壳长、壳厚、壳高、后闭壳肌直径、放射肋数及活体重。采用通径分析方法研究南海毛蚶5个形态特征对体重的总效应,并以综合决定系数为确定形态性状重要性的准则。结果表明,两性中壳厚、壳高和壳长与体重均为正相关(p<0.01),直接和间接途径都不是体重的限制因素。壳厚、壳高的平均综合决定系数分别为0.423和0.412,是影响体重最主要因素且都具有育种意义。     

准噶尔盆地吉木萨尔凹陷二叠系芦草沟组储层介—宏孔孔隙结构特征及控制因素

吉木萨尔芦草沟组页岩油资源潜力巨大,为探究其储层介—宏孔孔隙结构特征及控制因素,以研究区芦草沟组钻井岩心为对象,利用X射线衍射、铸体薄片、扫描电镜、孔渗测试、高压压汞、氮气吸附、分形理论、相关性分析等方法,对其储层特征、孔隙结构及控制因素进行了讨论。研究发现：1）研究区芦草沟组储层是一套以长英质碳酸盐岩（A岩）、长英质黏土岩（B岩）、灰/云质细粒长英沉积岩（C岩）、混积岩（D岩）为主的低孔—特低孔、特低渗储层,主要孔隙类型为溶孔,此外还发育有剩余粒间孔、晶间孔、微裂缝;2）研究区芦草沟组储层孔隙分布复杂,孔径分布曲线呈现多峰形,介孔提供了大部分孔容和比表面积;高压压汞计算的宏孔分形维数均值和氮气吸附计算的介孔分形维数均值分别为：2.864 7、2.507 5,介孔孔隙结构复杂程度相对较低;3）有机质丰度有利于A岩、B岩和C岩宏孔孔隙结构的发育,会导致C岩介孔和D岩孔容、比表面积减小;有机质演化程度对A岩介孔、B岩和C岩介孔起到建设作用,对C岩宏孔、D岩介—宏孔有破坏做用;4）脆性矿物含量越高C岩介孔和D岩孔容比表面积越大,而A岩、B岩宏孔、C岩宏孔孔容、比表面积减小;黏土矿物对A岩介孔、C岩介孔及D岩的孔隙系统发育起到建设作用,对B岩宏孔和C岩宏孔有破坏作用。孔隙结构的发育主要受有机质（有机质丰度、有机质演化程度）和矿物组份（脆性矿物含量、黏土矿物含量）的影响,不同岩性、不同尺度的孔隙发育影响因素各有差异。

     

第三系红层中石膏溶蚀特性及其对工程的影响

第三系红层中石膏分布比较广泛,大量的实验证明,石膏发生溶蚀的主要是含Ca2 的物质,并且溶蚀速率和与水接触的方式以及水头压力大小有直接关系。结合现场资料,将渗透系数K=10-5cm s作为石膏在第三系红层泥岩封闭下发生溶蚀的判据。同时针对水利工程中石膏溶蚀以及对砼的腐蚀性提出了相应的防治措施。     

Shape optimization of two-dimensional cavitators in supercavitating flows, using NSGA II algorithm

The reduction of energy consumption of high speed submersible bodies is an important challenge in hydrodynamic researches. In this paper, shape optimization of two-dimensional cavitators in supercavitating flows is studied. A two dimensional supercavitation potential flow passes a symmetric two dimensional cavitator, which is placed perpendicular to the flow in a channel of infinite length and immediately a cavity is formed behind the cavitator. This is because of the generation of a gas or vapor cavity between the body and the surrounding liquid due to the change in a high speed flow direction passing the cavitator. Drag force acting on this supercavitating body dictates the thrust requirements for the propulsion system, to maintain a required cavity at the operating speed. Therefore, any reduction in the drag force, by modifying the shape of the cavitator, will lead to decrease this force. This study concentrates on the optimization of two dimensional cavitators in order to decrease drag coefficient for a specified after body length and velocity in a potential flow. To achieve this goal a multi-objective optimization problem is defined to optimize cavitator shapes in supercavitating flow. The so-called NSGA II (Non-dominated Sorting Genetic Algorithm) algorithm is used as an optimization method. Design parameters and constraints are obtained according to supercavitating flow characteristics and cavitator modeling and objective functions are generated using Linear Regression Method. The obtained results are compared with other classic optimization methods, like the weighted sum method, for validation.     

软土场地基础隔震建筑减震性能研究

本文研究土与结构相互作用(SSI)对多层及中高层基础隔震建筑地震需求及隔震效率的影响规律,隔震层采用LRB铅芯橡胶与LNR普通橡胶隔震支座组合,就我国现行《建筑抗震设计规范》(GB50011-2010)中软土场地设置隔震层问题做探讨。提出土与基础隔震结构相互作用的简化计算模型,对不同场地及隔震设计目标下的多层及中高层基础隔震结构进行时程分析。研究表明:软土场地基础隔震建筑隔震层的有效隔震效率相对于硬土场地有所下降,必须通过设置具有一定规格的LRB支座来满足隔震目标。本文给出了铅芯橡胶支座极限变形需求随建筑层高及隔震目标变化的规律。     

黔西南水银洞金矿涌水坑道钻探难点与对策

针对黔西南水银洞金矿坑道钻探施工中的特大涌水钻孔,总结了该矿区坑道钻探施工难点,研究了涌水对钻进效率和岩心采取率的影响,探讨了普通取心工艺钻进时采用岩心上升系数的实践意义,提出绳索取心工艺钻进时的“泄”、“堵”、“疏”的解决思路,形成了解决该矿区Ⅰa含矿层的坑道钻探施工难点的对策,以期为类似地层条件的坑道钻探提供技术指导。     

Experimental study of extreme shear stress for shallow flow under simulated rainfall

The raindrop impact and overland flow are two major factors causing soil detachment and particle transportation. In this study, the turbulent characteristics of the shallow rain‐impacted water flow were investigated using a 2‐D fibre‐optic laser Doppler velocimetry (FLDV) and an artificial rainfall simulator. The fluctuating turbulent shear stress was computed using digital data processing techniques. The experimental data showed that the Reynolds shear stress follows a probability distribution with heavy tails. The tail probability increases with an increase of rainfall intensity or raindrop diameter, and it decreases with an increase of Reynolds number. A modified empirical equation was derived using both the raindrop diameter and rainfall intensity as independent variables to provide a better prediction of the Darcy‐Weisbach friction coefficient f under rainfall conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

一降水工程的施工和从中引出的思考

基坑降水是岩土工程中经常遇到的施工问题。本文展示了一个降水工程实例，从中引伸出本工程尚未遇到而在其他项目中可能会出现并应及时解决的一些技术问题，引起同行的关注与重视。     

用线性规划法求解瞬变电磁场反射系数

讨论了在水平层状介质中的反射系数的物理意义 ,推出时间域含有以反射系数序列为未知项的欠定方程组 ,提出用线性规划法求解瞬变电磁场反射系数序列 ,并给出求解思路和程序框图。对两个理论模型进行了处理 ,计算出了其反射系数。算例分析结果表明 ,算法可靠 ,程序可行。这一方法可用于瞬变电磁成像数值计算中。