Cartographic Study and Modeling of the Bakwanga Kimberlite Massive 5 at Kasai Oriental in the Democratic Republic of Congo

Bakwanga kimberlite massive 5 in Kasai Oriental is part of a set of 13 kimberlite massives numbered according to the order in which they were discovered. They are located on an alignment with a more or less W-E direction making up the Northern group known as Bakwanga. The importance of the Bakwanga kimberlite massives on the country’s economy in the production of diamonds sufficiently proves the interest of geological research work in this area. The objective of this work is to determine a mathematical model of the shape of the massive as close as possible to reality and through cartography. The cartographic study and modeling of this kimberlite massive were carried out using data from core samples taken on longitudinal and transverse profiles of the 50 × 50 meter mesh drilling plan intersecting this kimberlite massive. We intend to deduce the structure and lithostratigraphy of the kim-berlitic facies and the direct environment of massive 5. As a result, we note that the majority of surveys on the extent of this massive have intersected: Red clayey sand - Polymorphic sandstone - Nodular sandstone, with kaolin blocks and nodules - Epiclastic Kimberlite - Xenokimberlite - Massive Kimberlite - Mesozoic sandstone - Dolomite (enclosing). The shape of the Massive 5 model is vaguely elliptical with a W-E longitudinal axis of 575 m and N-S axis of 275 meters. Surveys have shown that Massive 5 is in fact composed of two pipes, located in the W (western pipe) and E (eastern pipe) ends of the massif. The two chimneys of the two pipes have walls ranging from subvertical at the eastern pipe to very steep walls of around 70˚ to 80˚ for the western pipe and the average diameter of the two pipes is ±50 meters. At level 600, the massive has an area of ±10.5 hectares and it gradually decreases in depth and the modeling of the latter shows a concentric decrease in the volume of the massive from the surface to depth in the shape of a mushroom. 3 eruptive phases established this Kimber-litic massive, the first two phases (old) of which formed the crater of the western pipe and the third formed the crater of the eastern pipe in the dolomites. These dolomites constitute everywhere the surrounding area of the massive;the distinction of these 3 phases is made possible thanks to Epiclastic deposits, Xenokim-berlites and massive Kimberlites.

Discussion on Pipe Model through Hydraulic Architecture of Pinus tabulaeformis Seedling

In the paper, the hydraulic architecture parameters of Pinus tabulaeformis seedlings (4 years old)were measured by improved flushing method under normal water condition in the green house and the basictheory of hydraulic architecture is used to discuss the rationality of the pipe model. The results of theexperiment and simulation show that the differences of hydraulic conductivity, specific conductivity and leafspecific conductivity is great in different stems and branches of Pinus tabulaeformis seedlings. The hydraulicconductivity of non-constriction area is higher than that of constriction area. The devotion of functionalxylem of stem to unit leaf growth is not a constant, namely, the Huber value is diverse. Even though the pipemodel has been accepted in some areas, its precondition is not perfect, and it is helpless in correctlyunderstanding the essence of water transport in seedlings from the prospective of water physiology.

AXIAL HEAT CONDUCTION MODEL TO PREDICT MAXIMUM HEAT REMOVE OF MINIATURE HEAT PIPE BASED ON GREY MODEL THEORY

Computer chip is always accompanied by the increase of heat dissipation and miniaturization. The miniature heat pipes are widely used in notebook computer to resolve the heat dissipation problems. Maximum heat removed model of miniature heat pipes building by grey model is presented. In order to know the foundation for modeling, the smooth grade of error examination is inquired and the accuracy of grey relational grade is verified. The model can be used to select a suitable heat pipes to solve electric heat problems in the future. Final results show that the grey model only needs four experiment data and its error value is less than 10%, further, it is better than computational fluid dynamics （CFD） model.

A p-version embedded model for simulation of concrete temperature fields with cooling pipes

Pipe cooling is an effective method of mass concrete temperature control, but its accurate and convenient numerical simulation is still a cumbersome problem. An improved embedded model, considering the water temperature variation along the pipe, was proposed for simulating the temperature field of early-age concrete structures containing cooling pipes. The improved model was verified with an engineering example. Then, the p-version self-adaption algorithm for the improved embedded model was deduced, and the initial values and boundary conditions were examined. Comparison of some numerical samples shows that the proposed model can provide satisfying precision and a higher efficiency. The analysis efficiency can be doubled at the same precision, even for a large-scale element. The p-version algorithm can fit grids of different sizes for the temperature field simulation. The convenience of the proposed algorithm lies in the possibility of locating more pipe segments in one element without the need of so regular a shape as in the explicit model.

IMPROVEMENT OF FLUID PIPE LUMPED PARAMETER MODEL

The traditional lumped parameter model of fluid pipe is introduced and itsdrawbacks are pointed out. Furthermore, two suggestions are put forward to remove these drawbacks.Firstly, the structure of equivalent circuit is modified, and then the evaluation of equivalentfluid resistance is change to take the frequency-dependent function into account. Both simulationand experiment prove that this model is precise to characterize the dynamic behaviors of fluid inpipe.

Simulation and model design of pipe-shell reactor for the direct synthesis of dimethyl ether from syngas

The simulation was made based on the model of pipe-shell reactor that was established by the model of global kinetics of synthesis of dimethyl ether from syngas over a bifunctional catalyst. The results of simulation showed that the selectivity for dimethyl ether （DME） and the conversion of CO were higher but the hot spot was kept below the temperature limit of the pipe-shell reactor. The suitable diameter of the pipe was φ38×2 mm, and the length of the pipe was 5.8 m. The optimal process conditions of the reactor were that the pressure was 5 MPa, the temperature of the cooling water was 240 ℃, and the temperature of the raw gas at inlet of the reactor was 220 ℃. The production of this reactor was 102800 t/y （ton per year） under these conditions.

Virtual Prototype Modeling and Simulation of Pipe Wagon Articulating System

Virtual prototype of pipe wagon articulating (PWA) system has been developed and simulated based on the kinematics and dynamics of machinery and Automatic Dynamic Analysis of Mechanical Systems (ADAMS) software. It has been integrated with real-time three dimensional (3-D) system simulations for detailed and responsive interaction with dynamic virtual environments. By using this virtual model, the conceptual design examination and performance analysis of the PWA system have been realized dynamically in virtual laboratory. System dynamic force, displacement and tension of pipe have been measured through verifying this 3- D virtual prototype. By comparing the static tension and dynamic tension of pipe, the difference between the two kind tensions has been found. The simulated dynamic tension is much greater than the static tension obtained from the static theory. The results attained in this work suggest that the conceptual designed PWA system can meet the requirements of the operation.

Centrifuge modeling of PGD response of buried pipe

A new centrifuge based method for determining the response of continuous buried pipe to PGD is presented. The physical characteristics of the RPI's 100 g-ton geotechnical centrifuge and the current lifeline experiment split-box are described: The split-box contains the model pipeline and surrounding soil and is manufactured such that half can be offset, in flight, simulating PGD. In addition, governing similitude relations which allow one to determine the physical characteristics, (diameter, wall thickness and material modulus of elasticity) of the model pipeline are presented. Finally, recorded strains induced in two buried pipes with prototype diameters of 0.63 m and 0.95 m (24 and 36 inch) subject to 0.6 and 2.0 meters (2 and 6 feet) of full scale fault offsets and presented and compared to corresponding FE results.

Mechanism of local scour around submarine pipelines based on numerical simulation of turbulence model

The mechanism of local scour around submarine pipelines is studied numerically based on a renormalized group （RNG） turbulence model. To validate the numerical model, the equilibrium profiles of local scour for two cases are simulated and compared with the experimental data. It shows that the RNG turbulence model can give an appropriate prediction for the configuration of equilibrium scour hole, and it is applicable to this situation. The local scour mechanism around submarine pipelines including the flow structure, shear stress distribution and pressure field is then analyzed and compared with experiments. For further comparison and validation, especially for the flow structure, a numerical calculation employing the large eddy simulation （LES） is also conducted. The numerical results of RNG demonstrate that the critical factor governing the equilibrium profile is the seabed shear stress distribution in the case of bed load sediment transport, and the two-equation RNG turbulence model coupled with the law of wall is capable of giving a satisfying estimation for the bed shear stress. Moreover, the piping phenomena due to the great difference of pressure between the upstream and downstream parts of pipelines and the vortex structure around submarine pipelines are also simulated successfully, which are believed to be the important factor that lead to the onset of local scour.

Simulation of Average Turbulent Pipe Flow: A Three-Equation Model

The aim of this study is to evaluate a three-equation turbulence model applied to pipe flow. Uncertainty is approximated by comparing with published direct numerical simulation results for fully-developed average pipe flow. The model is based on the Reynolds averaged Navier-Stokes equations. Boussinesq hypothesis is invoked for determining the Reynolds stresses. Three local length scales are solved, based on which the eddy viscosity is calculated. There are two parameters in the model;one accounts for surface roughness and the other is possibly attributed to the fluid. Error in the mean axial velocity and Reynolds stress is found to be negligible.

Analyses and Modeling of Laminar Flow in Pipes Using Numerical Approach

This paper investigate some important works done on numerical analysis and modeling of laminar flow in pipes. This review is focused on some methods of approach and the analytical tools used in analyzing of the important parameters to be considered in laminar flow;such as frictional losses, heat transfer etc. in laminar flow in pipes of different shapes, and the importance of laminar flow in its areas of applications. Prominent researchers have approached this from different perspectives. Some carried out analysis on the pressure drop as a function of permeability, some worked on friction factor analysis, some discussed heat transfer effects of laminar flow in the entrance region, while some discussed its applications in various industries. Some of these works were done considering a given form of pipe configuration or shape which is circular pipes. Only a few, of the literature reviewed have related their considerations to different forms of pipes. Most consider pipes to be majorly circular in shape, but in industries today some circular pipes have become elliptical in shape due to long time usage of the pipes, which would have contributed to increase in some different forms of losses in the industries. In engineering, efficiency and effectiveness improvement is the major goal, if a research work has been done, considering the important parameters in laminar flow showing their effects on different forms of pipe configuration as a result of pipe deformation due to usage, huge amount of money will be saved. This will show clearly how the efficiency of a given circular pipe has seriously been affected due to deformation, and the level of loss this has resulted to.

Mathematical Model of Steady State Operation in Jet Pipe Electro-Hydraulic Servo Valve

Jet pipe electro-hydraulic servo valve is the heart of feedback control systems,and it is one of the mechatronic components used for precision flow control application.It consists of several precision and ddicate components.The performance of the jet pipe servo valve depends on many parameters.During the developmental stage,it is very difficult to ascertain the function parameters.The steady-state analysis of jet pipe electro-hydraulic servo valve has been made to simulate its fluid characteristics （flowin,flow-out,leakage flow,recovery or load pressure,etc.） by mathematical modeling.Theoretical model was conducted on various affecting parameters on the pressure,the main flow rate of fluid,or leakage flow through the receiver holes.The major parameters studied are jet pipe nozzle diameters,receiver hole diameters,angle between the two centre-lines of receiver hole,nozzle offset,and nozzle stand-of distance.In this paper the research is important to determine and optimize the structural parameters of jet pipe servo valve.Thus,equations of the pressure and flow characteristics are set up and the optimal structural parameters of jet pipe are established.

Analytical dynamic model of elastic-plastic pipe-on-pipe impact

Abstract The dynamic response of pipe-on-pipe impact is described by an analytical model. The model considers the impact of a whipping pipe with one end hinged and the other end free on a simply-supported target pipe at its midpoint. Combining with the contact theory, the Laplace transformation, and the inverse Laplace transformation method, an analytical model based on the tubular beam theory is proposed to study the elastic-plastic behavior of a target pipe laterally impacted by a whipping pipe. Numerical simulations using the explicit finite element code MSC/DYTRAN are also performed. The results are coincident with the theoretical prediction.

盾构隧道下穿高铁路基变形影响规律及加固优化研究

为研究盾构隧道下穿高铁路基施工时对路基的影响规律,探究在隧道开挖过程中运用不同加固措施对既有高铁路基的影响程度。以西安市某地铁工程为依托,利用室内模型试验对比分析盾构隧道下穿高铁CFG桩复合路基过程中,无加固、超前管幕工法加固与地表袖阀管注浆加固3种隧道施工条件下,地表沉降值和沉降槽的空间分布规律;采用数值模拟分析验证超前管幕工法加固工况下盾构隧道下穿时,高铁路基、道床的位移变化规律。室内模型试验结果表明:盾构隧道施工中采用管幕工法加固后复合地基正上方的地表沉降最大值减小28.6%,采用袖阀管注浆加固后减小18.0%,并且采用两种加固措施后的CFG桩最大附加轴力均减小20%以上。因此,在隧道掘进过程中采用一定加固措施,可改善围岩稳定性,其中管幕工法加固效果更为显著。数值模拟分析表明:采取管幕工法加固施工与不采取加固措施相比,路基最大沉降量减少33.78%,道床最大沉降量减少45.08%。因此,管幕工法加固能够有效减小对既有高铁路基的影响。

基于管柱动力学的特深井通井组合刚度评价方法与应用

我国特深井钻井正处于快速发展阶段,受井眼尺寸大和深度深的影响,钻井过程中极易出现微井斜、扩径缩径和井壁台阶等,导致套管下入困难,因此通井钻具组合评价尤为重要。目前,现场使用的评价方法常忽略了管柱下入过程中与井壁的碰撞和变形,导致通井效果时好时坏。为了辅助现场施工,文章基于全井管柱动力学模型和HHT-α数值计算方法提出了一种能够模拟管柱下入的动态过程的通井钻具组合的评价方法,该方法考虑了实测井眼轨迹、井眼扩大率和下入阻力等要素。通过某特深井三开下套管前的钻具组合进行实例计算分析,表明井眼扩大率和套管串下入阻力对通井能力和套管下入影响较大,当井眼扩大率较小且套管串下入阻力较大时,需要使用刚度较大的多扶正器通井钻具组合。本方法可以实现实测井况条件下比较精准的刚度对比模拟,也成功指导了案例井?486 mm套管的安全下入。

S135钻杆接头螺纹三维参数化建模及力学特性分析

S135钢级钻杆在矿井勘探、探放水、瓦斯抽采等钻孔施工中得到了广泛使用。然而,由于钻杆接头螺纹承受轴向拉压、扭转、弯曲及其复合载荷的循环作用,导致接头螺纹的使用寿命远远低于其设计寿命,是整个钻杆结构中最薄弱的环节。因此,通过万能拉伸试验获得钻杆接头材料的力学性能参数,经计算转化得到其本构参数,对钻杆接头进行有限元分析。为了提高有限元分析效率,推导垂直于钻杆接头轴线的螺纹截面轮廓几何表达式,基于旋转、抬升、缩径和连接节点的设计思路,提出了一种考虑钻杆接头锥度和台肩的三维螺纹参数化建模方法,并根据单元和节点之间的关系开发了钻杆接头连接的参数化三维六面体网格建模程序,通过与交互式建模方法计算结果的对比验证了其有效性和可行性。此外,对上扣扭矩、压扭及压弯扭复合载荷作用下接头外螺纹的力学特性进行了分析。结果表明:3种工况下钻杆接头外螺纹上的应力近似呈现“浴盆”形态,第1螺纹牙上的应力最大;随着圈次的增加,螺纹牙上的应力迅速下降,最后一圈螺纹牙上的应力呈现上升趋势;在弯矩的作用下,螺纹牙上的应力具有非对称特征。在接头螺纹设计时,必须考虑井眼曲率的影响并且需要重点关注接头压缩边第1螺纹牙上的应力。

鄱阳湖区某典型圩堤堤基管涌发展过程试验研究

堤基管涌是造成鄱阳湖区圩堤险情乃至溃决的最主要原因之一,从机理上研究并揭示鄱阳湖区圩堤堤基管涌的致灾机制,对于应对管涌险情、科学开展应急抢险具有重要意义。基于鄱阳湖区某圩堤典型堤基结构,采用堤基原型土和自行设计制作的模型槽开展管涌物理模型试验,完整模拟了原型多层复杂堤基管涌发生、发展及致溃的全过程。结合试验现象对管涌发生和发展过程中的水力条件、堤基破坏机理和土体颗粒侵蚀速度等展开分析。研究结果表明,鄱阳湖区圩堤堤基结构中管涌破坏集中于下伏砂层,在渗透压的作用下上覆弱透水层被渗流击穿,于砂层与上覆层的接触面形成管涌通道后加速土体颗粒的侵蚀,最终导致堤基溃决;鄱阳湖区某典型圩堤堤基中夹于黏土层中的壤土层无法起到强弱透水层间过渡层的作用,土体颗粒侵蚀规律与无壤土过渡层的堤基结构相类似,形成表面管涌出口和堤基开裂的土体颗粒累计侵蚀量增长速率均低于0.1 g/s;该圩堤发生管涌的堤基平均总体临界水平坡降约为0.1。

Exact Solution of Unsteady Flow of Viscoelastic Fluid in a Pipe with Fractional Maxwell Model

The unsteady flow of viscoelastic fluid in a cylindrical pipe was investigated using the fractional Maxwell model. Two special cases of unsteady pipe flow were expressed. The first is start-up flow, and the second is oscillating flow. The exact solution of start-up flow under a constant pressure gradient was obtained by using the theories of Laplace transform and Fourier-Bessel series for fractional derivatives. The exact solution of oscillating flow was obtained by utilizing the separation of variables.

Mass-Spring-Damper Model with Steady State Parameters for Predicting the Movement of Liquid Column and Temperature Oscillation in Loop Heat Pipe

In order to investigate the mechanism of the temperature oscillation in loop heat pipes,this paper investigated the movement of the phase interface as the changed input power by a mass-spring-damper model.The model was solved with MATLAB and was used to explain the high-frequency and low-amplitude temperature oscillation.Temperature variation with the input power from 20 W to 75 W was investigated based on a LHP prototype in a literature.The model agreed well with the experimental data in the literature.The simulation results suggested that the movement of the liquid column was caused by the fluctuation of pressure difference applied on the liquid column and the stiffness coefficients of the vapor springs increasing with the input power.According to parameter analyses,the temperature oscillation at the outlet of the condenser can be weakened by increasing the mass of the liquid column and keeping the temperature at the outlet of the condenser steady.

基于三维流动的弯管模型的建立及流场分析

排气歧管是发动机的必要零部件之一,对发动机的性能有很大的影响。文章对排气歧管的弯曲管进行了研究,建立了弯管内气体流动的理论模型,利用FLUENT软件对弯管内气体流动状况进行了仿真,然后对两种弯曲管道(90°-56°管和90°-90°管)中的气体进行了对比分析。结果表明,90°-90°管道内的气体速度分布、压力分布和流线分布更为均匀,流动分离面积和涡流相对较小,速度均匀系数更接近于1,对柴油机进气的影响较小,柴油机的动力性能得以充分发挥。