水平管内空气-水两相流流型的混沌特征

在内径26 mm、长2 000 mm的水平管内,用差压变送器测量气液两相流不同流型下的压差波动信号,通过小波变换对信号进行除噪后,运用确定性混沌分析技术对信号进行分析,研究两相流系统分层流、泡状流、间歇流和环状流压差波动信号的混沌动力学行为.结果表明,气液两相流动系统为混沌动力系统,吸引子可用来表征气液两相流系统的动力学行为,混沌特征参数关联维D2和K熵可用来定量识别以上4种流型.     

伊春市南部“96.7”暴雨洪水

对１９９６年７月发生在伊春市南部的暴雨洪水进行雨情、水情和灾情的分析。     

Numerical analysis and geophysical monitoring for stability assessment of the Northwest tailings dam at Westwood Mine

The Westwood Mine aims to reuse the tailings storage facility #1(TSF #1) for solid waste storage, but,downstream of the Northwest dike is considered critical in terms of stability. This paper uses numerical modeling along with geophysical monitoring for assessing the Northwest dike stability during the restoration phase. The impact of waste rock deposition in the upstream TSF #1 is considered. The geophysical monitoring is based on electrical resistivity methods and was used to investigate the internal structure of the dike embankment in different deposition stages. The numerical simulations were performed with SLOPE/W code. The results show a factor of safety well above the minimum recommended value of 1.5. Geophysical monitoring revealed a vertical variation in the electrical resistivity across the dike, which indicates a multilayer structure of the embankment. Without any current in situ data, the geophysical monitoring helped estimating the nature of the materials used and the internal structure of the embankment. These interpretations were validated by geological observation of geotechnical log of the embankment. Based on this study, it is recommended that the water polishing pond be partly filled before waste rock is deposited in TSF #1. In addition, to ensure the stability of the dike, the piezometric head monitoring prior to and during waste rock deposition is recommended.     

Numerical investigation of particle saltation in the bed-load regime

This paper numerically investigates particle saltation in a turbulent channel flow having a rough bed consisting of 2–3 layers of densely packed spheres.In this study,we combined three the state-of-the-art technologies,i.e.,the direct numerical simulation of turbulent flow,the combined finite-discrete element modelling of the deformation,movement and collision of the particles,and the immersed boundary method for the fluid-solid interaction.Here we verify our code by comparing the flow and particle statistical features with the published data and then present the hydrodynamic forces acting on a particle together with the particle coordinates and velocities,during a typical saltation.We found strong correlation between the abruptly decreasing particle stream-wise velocity and the increasing vertical velocity at collision,which indicates that the continuous saltation of large grain-size particles is controlled by collision parameters such as particle incident angle,local rough bed packing arrangement,and particle density,etc.This physical process is different from that of particle entrainment in which turbulence coherence structures play an important role.Probability distribution functions of several important saltation parameters and the relationships between them are presented.The results show that the saltating particles hitting the windward side of the bed particles are more likely to bounce off the rough bed than those hitting the leeside.Based on the above findings,saltation mechanisms of large grain-size particles in turbulent channel flow are presented.     

大学英语写作中的横向与纵向图式建构及应用研究

英语写作是一项能够客观反映学生的思维能力和语言表达能力的主动性技能,但这项技能的养成需要有的放矢的训练才能获得.文章根据图式理论中的语言图式和形式图式概念,认为通过有针对性的训练能激活和构建英语写作所需的新图式,即句子层面的横向逻辑和段落层面的纵向逻辑.从而对培养学生养成英语思维,真正提高大学英语写作水平具有去"瓶颈"的作用.     

极轴式天线最小指向误差理论分析及其工程应用

本文针对天线极轴式调整机构进行了理论分析,严格推证出完整、准确的理论计算公式。并运用计算机进行了大量的误差分析计算,给出了在不同纬度上最佳偏置角ψ的数值和天线最佳极轴角的数值。按这些数据调整天线指向,天线的极轴不再平行于地轴,与目前国外资料中给出的天线极轴必须平行地轴的理论相比,本文的方法可以实现更高的跟踪精度和更大的跟踪范围,给实际使用提供了重要数据。     

Partitioning characteristics of gas channel of coal-rock mass in mining space and gas orientation method

In order to research the influence of coal-rock mass morphology of mining space on the flow law of gas, the laboratory physical model and numerical computation methods were adopted to simulate coal mining activities. The simulation results indicate that, after coal seam mining, the loose rock accumulation body of free caving, ordered rock arrangement body of plate damage rich in longitudinal and transverse fractures and horizontal fissure body formed by rock mass deformation imbalance are formed from bottom to top in the mining space. For these three types of accumulation bodies, there are essential differences in the accumulation state, rock size and gas breakover characteristics. According to this, the coal-rock mass in the mining space is classified into gas turbulence channel area, gas transitional flow channel area and gas seepage channel area. In the turbulence channel area, the gas is distributed transversely and longitudinally and gas diffuses in the form of convection with Reynolds number R_e more than 100; in the transitional flow channel area, one-way or two-way gas channels are crisscross and gas is of transitional flow regime with R_e between 10 and 100. In the seepage channel area, there are a few vertical gas channels with R_e less than 10. In this paper, the researches on the gas orientation method in different partitions were further carried out, gas orientation methods of low-level pipe burying, middle-level interception and high-level extraction were determined and an on-site industrial test was conducted, achieving the effective diversion of gas and verifying the reasonableness of gas channel partition.     

Numerical predictions and stability analysis of cavitating draft tube vortices at high head in a model Francis turbine

Draft tube vortex is one of the main causes of hydraulic instability in hydraulic reaction turbines, in particular Francis turbines. A method of cavitation calculations was proposed to predict the pressure fluctuations induced by draft tube vortices in a model Francis turbine, by solving RANS equations with RNG k-turbulence model and ZGB cavitation model, with modified turbulence viscosity. Three cases with different flow rates at high head were studied. In the study case of part load, two modes of revolutions with the same rotating direction, revolution around the axis of the draft tube cone, and revolution around the core of the vortex rope, can be recognized. The elliptical shaped vortex rope causes anisotropic characteristics of pressure fluctuations around the centerline of the draft tube cone. By analyzing the phase angles of the pressure fluctuations, the role of the vortex rope as an exciter in the oscillating case can be recognized. An analysis of Batchelor instability, i.e. instability in q-vortex like flow structure, has been carried out on the draft tube vortices in these three cases. It can be concluded that the trajectory for study case with part load lies in the region of absolute instability (AI), and it lies in the region of convective instability (CI) for study case with design flow rate. Trajectory for study case with over load lies in the AI region at the inlet of the draft tube, and enters CI region near the end of the elbow.     

内压对含软弱夹层盐岩储库稳定性影响的研究

通过建立含不同夹层厚度的圆柱形储库单腔三维模型,考虑不同恒压作用下长期蠕变,从腔体收缩率,围岩塑性区及位移矢量分布角度,分析运行内压对含软泥夹层盐岩腔体稳定性的影响。结果表明,腔体维持较高的运行压力,能有效减少腔体收缩,腔周塑性区及位移矢量发展,有利于腔体稳定。另外软泥夹层厚度在一定范围内增长对腔体的稳定性影响不太,在高内压作用下甚至可以忽略,这一结果对含软弱夹层层状盐岩腔体模型简化具有一定的指导意义。     

Variation of vertical and horizontal drilling rates depending on some rock properties in the marble quarries简

The main objective of this study is to determine the rates of vertically and horizontally oriented drilling processes in marble quarries and to observe the factors affecting the drilling rates in terms of physical and mechanical properties of the rocks. In situ drilling tests were performed in different marble quarries with different marble types and drilling times and penetration rates for a series of successive depth-increments were trying to be determined under vertically and horizontally oriented conditions. In order to understand the relation between the parameters that are investigated within the scope of this research, uniaxial compressive strength, Brazilian tensile strength, impact strength, Bohme abrasion strength, P-wave velocity, porosity, unit volume weight, Schmidt hardness index and brittleness index values were correlated with the drilling rates. It was noticed that the porosity and unit volume weight could be taken as the key parameters among them for obtaining meaningful correlation with drilling performance. It was also observed that the physical and mechanical rock properties are more relevant in vertical drilling than horizontal drilling.     

竖向及水平荷载共同作用下框支连续墙梁受力性能研究

通过按正交设计的８榀框支连续墙梁有限元数值计算，分析了这种结构在竖向及水平荷载作用下的应力分布特点及受力性能，这对了解这种结构的抗震性能，进行试验模型设计及建立内力计算公式，均有重要意义。     

Mechanism and control of water seepage of vertical feeding borehole for solid materials in backfilling coal mining

To solve the problem of water seepage of vertical feeding borehole for solid materials, we established the fluid-solid coupling dynamic model of groundwater flowing in rock mass adjacent to the vertical feeding borehole. Combining with the engineering geological conditions, we built a numeral model to study the influence rule of the aquifer hydraulic pressure and seepage location of feeding borehole on the amount of seepage with finite element numerical method. The results show that the nonlinear relationship is presented among the amount of seepage, the seepage location and aquifer hydraulic pressure. The higher the aquifer hydraulic pressure is, the closer the distance between seepage location and aquifer is, and the faster the harmful levels of aquifer will grow. In practice, we calculated the allowable seepage of feeding borehole by the optimum moisture content and natural moisture content of backfilling materials, and then determined the protection zone of feeding borehole, so the moisture content of backfilling materials can be controlled within the scope of optimum moisture content.     

竖向及水平荷载作用下带洞框支连续墙梁的受力性能研究

按正交设计法设计了８榀两跨带洞框支墙梁结构并进行了有限元数值计算，对其在竖向及水平荷载共同作用下的应力分布规律和受力性能进行了分析。     

密肋壁板结构中复合墙体的竖向承载力及稳定性研究

通过对1/2模型密肋复合墙体在单调竖向荷载作用下试验研究,探讨墙体在竖向荷载作用下的受力特点及简化计算模型;分析墙体竖向受压承载力计算公式;考虑到密肋复合墙体自身支撑情况的特点,给出墙体计算高度的理论公式;提出外框柱对高厚比的影响系数,并对墙体高厚比限值进行了修正;最后得出墙体的高厚比验算公式.理论与试验表明:考虑梁的刚度及房屋高度的影响的计算模型更接近试验结果;提出的高厚比验算公式可满足密肋壁板结构中复合墙体的稳定性要求,具有一定的实际工程意义.     

海底电缆数据中压力分量与 垂直分量的分析与应用

根据海底电缆多波勘探中压力检波器和垂直方向速度检波器产生相同极性的上行波信号和相 反极性下行波信号的原理,通过将压力分量数据和垂直分量数据匹配后进行相加合并,可以消除水层鸣 震。从理论上分析了速度检波器和压力检波器对上、下行波场以及水层鸣震的响应特点,得到在理想情 况下消除水层鸣震的两种数据振幅匹配系数,用该匹配系数对理论模型模拟的两种数据进行相加处理, 并在分析实际数据振幅、频率、波形和初至特征的基础上,对实际资料进行了试算,验证了该方法的有 效性。     

对防止低压内缸中分面漏汽措施的探索

汽轮机低压内缸中分面的漏汽降低了机组的出力及效率,利用ANSYS软件分析了国产引进型300 MW、600 MW机组低压内缸在变工况下因温差产生的热应力,分析了法兰螺栓的预紧力,从而得出低压内缸漏汽的原因,并提出了防止低压内缸中分面漏汽的措施.     

水下航行体垂直出筒流体动力特性研究

采用数值仿真的方法研究了水下航行体垂直发射出筒过程多相流场和流体动力特性演化规律．结 合动网格技术,采用多相流Mixture模型、Singhal空化模型及标准的A—s湍流模型,对混合流场的RANS方 程进行求解,进而求解了水下航行体运动的固体边界与运动流场相互作用形成了流一固耦合问题,使用此方 法,实现了在重力影响下水下航行体垂直发射出筒过程和流体动力特性进行数值模拟研究,分析了高压气团 对航行体出筒过程中的水弹道及其流体动力特性的影响,分析了航行体压差系数、粘性系数和总力系数波动 的原因     

吉贾尔-帕坦喀喇昆仑公路沿线落石和边坡稳定性数值研究

在中巴经济走廊的重要通道喀喇昆仑公路（KKH）沿线，由于构造运动和降雨渗透对破碎岩石和边坡稳定性的不利作用，造成了大量落石和不稳定边坡。利用数值软件DIPS、GeoRock 2D和SLIDE对巴基斯坦北部吉贾尔-帕坦喀喇昆仑公路沿线的落石和边坡稳定性进行了数值研究；以喀喇昆仑公路沿线两个主要的易受落石影响的路段为例，研究落石和边坡的失稳机理。对4组节理进行的赤平投影分析表明：两处边坡断面均易发生平面破坏和楔形破坏。基于极限平衡理论，在静力条件下，边坡断面1的安全系数为0.917，处于不稳定状态，边坡断面2的安全系数为1.131，处于欠稳定状态；但在地震条件下，两处断面边坡的安全系数均小于1，处于不稳定状态。研究结果表明，边坡断面1和断面2的落石回弹高度分别为33 m和29 m。边坡断面1的落石速度在0.5~44 m/s，总动能达到1 135.099 kJ，而边坡断面2的落石具有0.5~40.901 m/s的速度和973.012 kJ的破坏能力。研究表明，KKH沿线的落石和滑坡具有极大的破坏潜力。     

Phase field simulation of the interface morphology evolution and its stability during directional solidification of binary alloys

The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been studied with the B-S phase field model. Simulated results reproduced the morphology transitions of deep cell to shallow cell and shallow cell to plane front. The primary cellular spacing, depth of groove and effective solute redistribution coefficient for different V and G are compared. The absolute stability under high pulling speed and high temperature gradient has also been predicted, which is in agreement with the Mullins-Sekerka (M-S) stability theory. Supported by the National Natural Science Foundation of China (Grant No. 50401013)