浅谈用三维计算法和微分法计算淤地坝坝体工程量

鉴于目前多数设计单位使用的横断面法手工计算坝体工程量的方法存在效率低、准确性不高等问题,结合工作实际,在假定坝体横断面均匀的前提下,提出了计算坝体工程量的新方法——三维计算法和微分法,详细介绍了三维计算法的计算原理与方法、微分法的具体应用及用三维计算法和微分法计算淤地坝坝体工程量的特点。

离心机转子系统自激失稳的“三维”计算法及试验结果

本文主要讨论充液离心机转子系统自激失稳的“三维”计算方法。该方法采用了简单的质量-弹簧系统的振动来代替具有无限自由度的液体轴向非定常振动,保留解析解中代表液体二维非定常运动的项,从而克服了解析解出现密集奇点给稳定性判断带来的困难,获得了悬臂型离心机转子系统的自激失稳边界,并通过试验验证了“三维”计算结果与试验结果之间的一致性。

高陡地形料场储量计算方法探讨

传统的天然建筑材料储量计算方法由于受地形起伏、有用层厚度不均、勘探点布置不规则等影响,在使用时存在多种限制条件。随着计算机技术的发展,三维模型计算法以准确、快捷和高效的优势在工程中得到了越来越广泛的应用。文章以某人工骨料场为例,在满足相关规程的条件下,将传统平行断面法与三维模型储量计算结果进行对比,结果表明:高陡地形料场储量计算中,虽然平行断面法增加断面数量能够提高料场储量的计算精度,但其效果并不明显;随着断面间距的加密,平行断面法的计算结果有向三维模型计算法计算结果收敛的趋势,三维模型计算法相比平行断面法计算结果更接近料场实际储量,验证了三维模型计算法储量计算具有可行性、准确性。

电子全站仪三维方向观测法数据处理模块的研制及其应用

本文简单介绍了应用三维方向观测法的背景、概念、观测方法及其计算公式,并用VB以类模块为对象变量编程,实现基于方向观测法数据处理模块的研制。利用TPS2000全站仪采集室外相机检校场标识控制点的原始数据作为本模块的应用实例,与SSoffice软件计算结果基本一致。模块数据处理的精度准确可靠,可以满足相机检校标识控制点的三维坐标精度。

淤地坝工程量计算及自动绘图软件系统的研发

为提高淤地坝工程坝体工程量计算的效率、解决淤地坝工程设计图自动绘制等问题,结合工作实际,在假定坝体横断面均匀的前提下,开发了淤地坝工程量计算及自动绘图软件系统。该系统开发的主要技术难点是各个计算断面坐标的确定、三维计算法和微分法计算坝体工程量、自动绘图各个坐标数据的确定等。该系统与以往的横断面法手工计算淤地坝工程量和手工制图相比,具有高效性、准确性以及可操作性强的优势。

不同数值模拟方法预测消声器传递损失的比较研究

分别采用三维有限元法(Finite element method,FEM)和三维时域计算流体力学法(Computational fluid dynamics,CFD)对消声器的传递损失进行预测,并将计算结果与文献中的实验数据进行对比,然后从计算结果的准确性,计算耗时和易用性三个方面对这两种数值方法进行比较研究。研究结果表明:无论消声器内是否存在气体流动,两种方法都能够对消声器的传递损失进行合理预测。相比之下,时域CFD法能够获得更加准确的计算结果,但计算时间消耗较长;有限元法计算时间消耗较短,但应用起来较为复杂。

The algorithm of 3D multi-scale volumetric curvature and its application

To fully extract and mine the multi-scale features of reservoirs and geologic structures in time/depth and space dimensions, a new 3D multi-scale volumetric curvature （MSVC） methodology is presented in this paper. We also propose a fast algorithm for computing 3D volumetric curvature. In comparison to conventional volumetric curvature attributes, its main improvements and key algorithms introduce multi-frequency components expansion in time-frequency domain and the corresponding multi-scale adaptive differential operator in the wavenumber domain, into the volumetric curvature calculation. This methodology can simultaneously depict seismic multi-scale features in both time and space. Additionally, we use data fusion of volumetric curvatures at various scales to take full advantage of the geologic features and anomalies extracted by curvature measurements at different scales. The 3D MSVC can highlight geologic anomalies and reduce noise at the same time. Thus, it improves the interpretation efficiency of curvature attributes analysis. The 3D MSVC is applied to both land and marine 3D seismic data. The results demonstrate that it can indicate the spatial distribution of reservoirs, detect faults and fracture zones, and identify their multi-scale properties.

Parallel rapid relaxation inversion of 3D magnetotelluric data

We implement a parallel algorithm with the advantage of MPI （Message Passing Interface） to speed up the rapid relaxation inversion for 3D magnetotelluric data. We test the parallel rapid relaxation algorithm with synthetic and real data. The execution efficiency of the algorithm for several different situations is also compared. The results indicate that the parallel rapid relaxation algorithm for 3D magnetotelluric inversion is effective. This parallel algorithm implemented on a common PC promotes the practical application of 3D magnetotelluric inversion and can be suitable for the other geophysical 3D modeling and inversion.

New approach to develop a 3D non-isothermal computational framework for injection molding process based on level set method

The simulation of three-dimensional （3D） non-isothermal, non-Newtonian fluid filling process is an extremely difficult task and remains a challenging problem, which includes polymer melt flow with free surface coupled with transient heat transfer. This paper presents a full 3D non-isothermal two-phase flow model to predict the complex flow in melt filling process, where the Cross-WLF model is applied to characterize the rheological behav- ior of polymer melt. The governing equations are solved using finite volume method with SIMPLEC algorithm on collocated grids and the melt front is accurately captured by a high resolution level set method. A domain exten- sion technique is adopted to deal with the complex cavities, which greatly reduces the computational burden. To verify the validity of the developed 3D approach, the melts filling processes in two thin rectangular cavities （one of them with a cylindrical insert） are simulated. The predicted melt front interfaces are in good agreement with the experiment and commercial software prediction. For a case with a rather complex cavity, the dynamic filling process in a hemispherical shell is successfully simulated. All of the numerical results show that the developed numerical procedure can provide a reasonable orediction for injection molding process.

3D FEM analysis for layered rock considering anisotropy of shear strength

An empirical expression of cohesion （C） and friction angle （Ф） for layered rock was suggested. This expression was compared with a test result made by the former researchers. The constitutive relationship of a transversely isotropic medium and Mohr-Coulomb criterion in which C and Ф vary with directions were employed, and a relative 3D elasto-plastic FEM code was developed, in which the important thing was to adopt a search-trial method to find the orientation angle （p） of shear failure plane （or weakest shear plane） with respect to the major principal stress as well as the corresponding C and Ф Taking an underground opening as the calculation object, the numerical analyses were carried out by using the FEM code for two cases of transversely isotropic rock and isotropic rock, respectively, and the computation results were compared. The results show that when the rock is a transversely isotropic one, the distributions of displacements, plastic zones and stress contours in the surrounding rock will be non-axisymmetric along the tunnel＇s vertical axis, which is very different from that of isotropic rock. The stability of the tunnel in transversely isotropic rock is relatively low.

Three-dimensional forward modeling for magnetotelluric sounding by finite element method

A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forward modeling was derived from Maxwell's equations using general variation principle. The divergence condition was added forcedly to the electric field boundary value problem, which made the solution correct. The system of equation of the finite element algorithm was a large sparse, banded, symmetric, ill-conditioned, non-Hermitian complex matrix equation, which can be solved using the Bi-CGSTAB method. In order to prove correctness of the three-dimensional magnetotelluric forward algorithm, the computed results and analytic results of one-dimensional geo-electrical model were compared. In addition, the three-dimensional magnetotelluric forward algorithm is given a further evaluation by computing COMMEMI model. The forward modeling results show that the algorithm is very efficient, and it has a lot of advantages, such as the high precision, the canonical process of solving problem, meeting the internal boundary condition automatically and adapting to all kinds of distribution of multi-substances.

Introduction and evaluation of a novel hybrid brattice for improved dust control in underground mining faces: A computational study

A proper control and management of dust dispersion is essential to ensure safe and productive underground working environment. Brattice installation to direct the flow from main shaft to the mining face was found to be the most effective method to disperse dust particle away from the mining face. However,it limits the movement and disturbs the flexibility of the mining fleets and operators at the tunnel. This study proposes a hybrid brattice system- a combination of a physical brattice together with suitable and flexible directed and located air curtains- to mitigate dust dispersion from the mining face and reduce dust concentration to a safe level for the working operators. A validated three-dimensional computational fluid dynamic model utilizing Eulerian–Lagrangian approach is employed to track the dispersion of dust particle. Several possible hybrid brattice scenarios are evaluated with the objective to improve dust management in underground mine. The results suggest that implementation of hybrid brattice is beneficial for the mining operation: up to three times lower dust concentration is achieved as compared to that of the physical brattice without air curtain.

试述支架支撑加强结构的设计

通过UG三维仿真计算找出支撑加强结构的薄弱点,再通过适当的加强,从而优化设计的新方法。

Numerical simulation of asphalt mixture based on three-dimensional heterogeneous specimen

In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic （where mastic is a kind of fine mixture composed of asphalt binder mixed with fines and fine aggregates） and air voids, based on three-dimensional （3D） heterogeneous specimen, X-ray computerized tomography （X-ray CT） was used to scan the asphalt specimens to obtain the real internal microstrnctures of asphalt mixture. CT images were reconstructed to build up 3D digital specimen, and the viscoelastic properties of mastic were described with Burgers model The uniaxial creep numerical simulations of three different levels of aggregate gradation were conducted. The simulation results agree well with the experimental results. The numerical simulation of asphalt mixture incorporated with real 3D microstructure based on finite element method is a promising application to conduct research of asphalt concrete. Additionally, this method can increase the mechanistic understanding of global viscoelastic properties of asphalt mixtures by linking the real 3D microstructure.

THE MOLECULAR ALGORITHM OF CONNECTIVITY BASED ON THREE DIMENSIONAL DNA STRUCTURE

Inspired by the potential computational capability of 3-Dimensional (3D) DNA structure,this paper presents a graph structure constructed by k-armed (k = 3or 4) branched junction DNA molecules to explore the possibility of solving some intractable problems. In the proposed procedure,vertex building blocks consisting of 3,4-armed branched junction molecules are selectively used to form different graph structures. After separating these graph structures by gel electrophoresis,the connec-tivity of this graph can be determined. Furthermore,the amount of potential solutions can be reduced by a theorem of graph theory.

3D structure parameterization design and modeling for irregular structure of stope bottom

Stope mining design is a very important and complicated task in daily production design and technical management of an underground mine.Based on workface technology and human-computer interaction technology,this study introduces a method of 3D parametric design for the irregular structure of stope bottoms,and focuses on solving technical problems in surface modeling of stope bottom structure.Optimization of the minimum span length algorithm(MSLA) and the shortest path search algorithm(SPSA) is conducted to solve the problem of contour-line based instant modeling of stope bottom structures,which makes possible the 3D parametric design for irregular structure of stope bottom.Implementation process and relevant methods of the proposed algorithms are also presented.Feasibility and reliability of the proposed modeling method are testified in a case study.In practice,the proposed 3 D parameterization design method for irregular structure stope bottom proves to be very helpful to precise 3D parametric design.This method is capable of contributing to improved efficiency and precision of stope design,and is worthy of promotion.

Design of Process Centrifugal Compressor： an Adapted Algorithm

Considering the essential and influential role of centrifugal compressors in a wide range of industries makes most of engineers research and study on design and optimization of centrifugal compressors. Centrifugal compressors are the key to part ofoil, gas and petrochemical industries as well as gas pipeline transports. Since complete 3D design of the compressor consumes a considerable amount of time, most of active companies in the field, are profoundly interested in obtaining a design outline before taking any further steps in designing the entire machine. In this paper, a numerical algorithm, named ACDA （adapted compressor design algorithm） for fast and accurate preliminary design of centrifugal compressor is presented. The design procedure is obtained under real gas behavior, using an appropriate equation of state. Starting from impeller inlet, the procedure is continued on by resulting in numerical calculation for other sections including impeller exit, volute and exit diffuser. Clearly, in any step suitable correction factors are employed in order to conclude in precise numerical results. Finally, the achieved design result is compared with available reference data.

Discussion and study on contraction joints for RCC gravity dam

Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Using this method, the temperature and the thermal stress fields developed in the RCC gravity dam of the Longtan project with or without a longitudinal joint during construction and operation are calculated so as to simulate the construction process. The computation results show that the value of the thermal stresses developed in the dam even, without any longitudinal joint, could meet the design criteria provided the placement temperature is adequately controlled.

南京长江第四大桥北锚碇锚固系统安装测量定位

北锚碇锚固系统是全桥关键部件,为最大限度降低定位偏差产生的附加应力,确保系统安全度,锚固钢板必须精确定位并可靠固定,施工定位要求高、难度大,重点介绍了锚固系统三维坐标计算方法、锚固钢板定位及精度分析。

海外大型悬索桥型钢锚固系统安装定位技术

型钢锚固系统是悬索桥的关键部位,安装精度要求高。马普托大桥南锚锭型钢锚固系统安装定位采用了整体式定位钢支架、锚固梁安装与锚体混凝土交替施工、限位板及多向千斤顶进行锚固梁粗定位及精调整、锚固系统三维坐标计算方法及精度分析等施工技术,有效地控制了锚固梁的安装精度,取得了很好的施工效果。