基于博弈论组合赋权TOPSIS法的深部进路参数优选

采取标度扩展AHP法、熵值法2种方法对各指标进行赋权得到主客观权重;并基于博弈论思想构造的组合赋权优化模型计算各评判指标的组合权重;最终建立基于博弈论组合赋权TOPSIS法的深部采场结构布置参数评价模型.结合实例计算得到各方案贴近度:方案1为58.05 %;方案2为41.95 %;方案3为41.61 %;方案4为56.87 %,因此优选出较优方案为方案1采场进路为4.5 m×4 m,矿柱非胶结充填.与线性加权法及乘法归一法2种组合法对比,结果表明,3种组合赋权TOPSIS法得到的4种方案的优劣排序均一致,方案1结果均较优,其次是方案4、方案2、方案3;说明博弈论组合赋权模型合理可行.      

Upwind Conservative Scheme for the Saint Venant Equations

An upwind conservative scheme with a weighted average water-surface-gradient approach is proposed to compute one-dimensional open channel flows. The numerical scheme is based on the control volume method. The intercell flux is computed by the one-sided upwind method. The water surface gradient is evaluated by the weighted average of both upwind and downwind gradients. The scheme is tested with various examples, including dam-break problems in channels with rectangular and triangular cross-sections, hydraulic jump, partial dam-break problem, overtopping flow, a steady flow over bump with hydraulic jump, and a dam-break flood case in a natural river valley. Comparisons between numerical and exact solutions or experimental data demonstrated that the proposed scheme is capable of accurately reproducing various open channel flows, including subcritical, supercritical, and transcritical flows. The scheme is inherently robust, stable, and monotone. The scheme does not require any special treatment, such as artificial viscosity or front tracking technique, to capture steep gradients or discontinuities in the solution.     

基于层次分析对某铁矿的采矿方法选择

针对安徽龙桥铁矿现有的采矿方式无底柱分段崩落法中崩落层难以形成，存在大量采空区等安全隐患问题.提出采用层次分析法和模糊数学方法对多种采矿方案进行综合评判和优选，在选择较优采矿方案的过程中，针对影响采矿方案的指标建立采矿方案综合评判指标体系，将生产能力、采矿成本、千吨采切比和劳动强度等转换成判断矩阵, 从而建立模糊综合评判模型，最后采用模糊数学方法计算出每个采矿方案的综合优越度，得出龙桥铁矿的备选采矿方案的各优越度为33.8 %, 21.3 %, 26.7 %, 25.2 %，因此第1种采矿方案为较优采矿方案.      

基于随机数结构面分维数估算的改进投影覆盖法

岩石结构面的定量化描述对于理解结构面的力学性质至关重要,投影覆盖分形描述法是结构面定量化表征的主要方法之一.然而,投影覆盖法计算结构面分形维数时存在三角形单元划分的缺陷.从概率分析角度考虑,将随机数应用于三角形单元的划分中,提出了基于随机数估算结构面分维数的投影覆盖法.应用改进投影覆盖法计算了红砂岩结构面的分维数,获得了120个分维值,并将其作为一个分维数样本;然后分析了此样本的分布特征,并将样本均值作为结构面分维数的精准值.实例分析证明,采用改进投影覆盖法所获分维数样本是来自正太分布总体;投影覆盖法计算的分维数几乎是改进投影覆盖法所获结果的极限值;基于随机数进行三角形单元划分更符合实际结构面形貌特征,从而计算的分维数更精准.      

An Automatic Newton‐Raphson Scheme

This article presents an automatic Newton‐Raphson method for solving nonlinear finite element equations. It automatically subincrements a series of given coarse load increments so that the local load path error in the displacements is held below a prescribed threshold. The local error is measured by taking the difference between two iterative solutions obtained from the backward Euler method and the SS21 method. By computing both the displacement rates and the displacements this error estimate is obtained cheaply. The performance of the new automatic scheme is compared with the standard Newton‐Raphson scheme, the modified Newton‐Raphson scheme with line search, and two other automatic schemes that are based on explicit Euler methods. Through analyses of a wide variety of problems, it is shown that the automatic Newton‐Raphson scheme is superior to the standard Newton‐Raphson methods in terms of efficiency, robustness, and accuracy.     

烟化炉吹炼终点判断图象处理研究

提出了一种通过对烟化炉三次风口火焰图象二值化分析处理 ,判断烟化炉吹炼点的方法和技术思路。实验结果表明 ,该方法可以较好地将吹炼终点判断出来。     

Fractional Steps Scheme of Finite Analytic Method for Advection–Diffusion Equation

For simply finding local analytic solution, the time derivative in the traditional finite analytic (FA) method is generally replaced with a first-order finite difference approximation as a source term. However, this may induce excessive numerical diffusion, especially for advection-dominated transport problems. In this paper, a fractional steps scheme of the FA method without using the finite difference approximation to time derivative is proposed by applying the one-dimensional FA method whose local analytic solution is obtained from both spatial and time domains, together with the method of fractional steps. Four hypothetical examples, including two-dimensional and three-dimensional cases, are employed to investigate this newly proposed method as compared with the traditional FA method, the optimal unsteady FA method, and the alternating direction scheme of the hybrid FA method. The results show that the fractional steps scheme of the FA method can greatly diminish numerical diffusion and is superior to the other methods compared herein.     

Low-Tension Cable Dynamics: Numerical and Experimental Studies

An efficient and robust numerical method is presented for the dynamic analysis of low-tension cables. The numerical solution strategy is based on finite-difference approximations of differential equations. In a scheme used by other researchers, known as the box scheme, the trapezoidal method is employed in both space and time domains. This scheme, however, gives rise to spurious high-frequency oscillations in cable tension response, as discovered in the research work reported herein. A modified box scheme is proposed to eliminate the problem. To improve computational efficiency, an iterative procedure is used to solve the resulting nonlinear simultaneous equations. A “free-fall” problem of cable dynamics involving low tension and large displacement motion is studied numerically. An experimental program is carried out to verify the accuracy of the numerical solution with regards to cable tension response.     

江西省大茅山铜钼矿通风方式的探讨

对国内外无底柱分段崩落法采场通风方式,进行了系统的研究,在此基础上,提出在大茅山铜钼矿开采条件下的贯穿风流通风新形式,研究表明,该方案是当前无底柱分段崩落法的最佳通风方式之一.     

Improvement of Eigensolution Method for Nonproportionally Damped Systems by Step Length

This study presents an efficient eigensolution method for nonproportionally damped systems. The proposed method is obtained by applying the accelerated Newton–Raphson technique and the orthonormal condition of the eigenvectors to the linearized form of the quadratic eigenproblem. In the Newton–Raphson scheme, a step length and a selective scheme are introduced to increase the convergence of the solution. The step length can be evaluated by minimizing the norm of the residual vector using the least-squares method. While the singularity may occur during the factorizing process in other iteration methods such as the inverse iteration method and the subspace iteration method if the shift value is close to an exact eigenvalue, the proposed method guarantees the nonsingularity by the orthonormal condition of eigenvectors, which can be proved analytically. A numerical example is presented to demonstrate the effectiveness of the proposed method.     

Treatment of Natural Geometry in Finite Volume River Flow Computations

A method is proposed for the treatment of irregular bathymetry in one-dimensional finite volume computations of open-channel flow. The strategy adopted is based on a reformulation of the Saint-Venant equations. In contrast with the usual treatment of topography effects as source terms, the method accounts for slope and nonprismaticity by modifying the momentum flux. This makes it possible to precisely balance the hydrostatic pressure contributions associated with variations in valley geometry. The characteristic method is applied to the revised equations, yielding topographic corrections to the numerical fluxes of an upwind scheme. Further adaptations endow the scheme with an ability to capture transcritical sections and wetting fronts in channels of abrupt topography. To test the approach, the scheme is first applied to idealized benchmark problems. The method is then used to route a severe flood through a complex river system: the Tanshui in Northern Taiwan. Computational results compare favorably with gauge records. Discrepancies in water stage represent no more than a fraction of the magnitude of typical bathymetry variations.     

基于Q系统的某铜矿巷道分级支护技术及工程应用

合理的支护方式是控制巷道稳定和变形的重要手段之一,而工程岩体质量评价是确定合理支护方案的重要依据.针对某铜矿存在的支护方式单一、支护效率低、支护成本较高的问题,采用Q系统和RMR法对该矿山4个工程岩组进行了岩体质量分级.基于Q系统支护图,并结合矿山支护工艺、施工条件等因素,制定和优化了分级支护方案及支护参数;利用RMR...     

广西大新锰矿工业场地边坡稳定分析

在分析大新锰矿工业场地边坡施工情况的基础上,提出新的设计方案,并通过强度折减法的FLAC3D数值模拟的方法,计算了边坡的应力、位移、剪应变增量与速度矢量分析、塑性区和安全系数,在此基础上分析和讨论确定大新锰矿工业场地边稳定性较好,新的设计方案所设计的边坡符合技术规范的要求。在安全经济的基础上提出新的边坡设计方案:砂土台阶坡面角为38(°)、岩质台阶坡面角50(°)、清扫平台8 m、安全平台5 m、最终边坡角41(°)、并段台阶高度96 m。根据边坡稳定性分析的结果可以有效的指导边坡的设计方案制定和现场施工,确保施工方案安全可靠。     

Some features of the control of atrophic rhinitis (author''s transl)]

The results obtained by a number of control measures in 152 cases of atrophic rhinitis in the province of North Brabant in 1975 are reviewed. So-called "elimination of piglets" from the herd for a few weeks and treatment of the newborn piglets in accordance with a fixed scheme are the measures stressed in this regard moreover, when this scheme of treatment is adopted in a contaminated environment, i.e. without any taking over by the authorities, it also offers certain prospects. The method of control widely used in the Netherlands so far (elimination of piglets not followed by a scheme of treatment) was not sufficiently successful.     

Computerized detection of masses in digitized mammograms using single-image segmentation and a multilayer topographic feature analysis

RATIONALE AND OBJECTIVES: We developed and evaluated a computer-aided detection (CAD) scheme for masses in digitized mammograms. METHODS: A multistep CAD scheme was developed and tested. The method uses a technique of single-image segmentation with Gaussian bandpass filtering to yield a high sensitivity for mass detection. A rule-based multilayer topographic feature analysis method is then used to classify suspected regions. A set of 260 cases, including 162 verified masses, was divided into two subsets; one set was used to set the rule-based classification and one was used to test the performance of the scheme. RESULTS: In a preliminary clinical study, the implemented detection scheme yielded 98% sensitivity with a false-positive detection rate of less than one false-positive region per image. CONCLUSION: Single-image segmentation methods seem to have high sensitivity in selecting true-positive mass regions in the first stage of a CAD scheme. A multilayer topographic image feature analysis method in the second stage of a CAD scheme has the potential to significantly reduce the false-positive detection rate.     

基于响应面优化法的某矿山充填配比优化

为得到某矿山充填最佳配比方案,在实验的基础上利用BBD 响应面设计法确定充填配比的最佳条件.通过实验得到影响充填体强度因素的排序,并得到最佳配比实验方案,即灰砂比（质量比）1∶4,养护时间为28 d,浓度为75%,按照此方案得到的充填体强度为5.48 MPa,与理论值5.71 MPa的误差为4.2%,利用响应面法优化得到充填体的配比方案真实可靠,能够为矿山充填配比的应用提供理论依据,在实践中具有指导意义.而真实值比理论值偏低,可能是试验过程中仍存在干扰因素,建议在后续深入研究过程中考虑的因素要更彻底、更全面.     

基于逆系统方法的内模AGC控制方式

 针对压力AGC在提高厚度控制精度方面存在的问题,利用非线性弹跳方程,提出了基于逆系统方法的内模AGC控制方式。求得AGC系统的逆模型,逆模型与原系统串联为伪线性系统,将AGC系统中参数摄动、建模误差、干扰等不确定因素考虑进去,引入内模控制方案,理论证明逆系统内模控制对AGC系统控制的有效性。仿真结果验证了基于逆系统方法的内模AGC控制策略具有好的抗干扰性能,且系统鲁棒性强,控制算法简单易于现场实现。     

基于凝固传热模型的轴承钢GCr15二冷研究与应用

采用Gleeble 3500热应力/应变模拟机对轴承钢GCr15进行了高温力学性能测定,根据实际测量的结果,优化原有二冷制度并提出了适合轴承钢二冷冶金准则的二冷水表。并根据实际情况建立了大方坯连铸凝固传热模型,通过射钉试验表明模型准确可靠,在此基础之上提出了基于凝固传热模型的动态二冷控制方法,通过生产实践表明采用特征拉速控制二冷配水可以有效改善铸坯质量。     

Medical scheme expenditure on dental care--a smaller slice of the pie

Medical schemes play an important part in financing dental care in the private sector and provide many dental practitioners with a substantial source of income. Data on medical scheme expenditure indicates a steady decline in their proportional pay-out for dental care during the period 1985 to 1994. In 1985 more than 12 per cent of total medical scheme expenditure was spent on dental care. In 1994 this had reduced to 8.37 per cent. In the present study, the historical trend (1985-1994) of medical scheme expenditure on dental care is analysed. By using the least squares method, the annual medical scheme expenditure on dental care is computed for the next eleven years (1995-2005). If the secular trend continues, less than 4 per cent of medical scheme expenditure will be paid for dental care by the year 2005.     

Optimally weighted wavelet transform based on supervised training for detection of microcalcifications in digital mammograms

We are developing a computer-aided diagnosis (CAD) scheme for detection of clustered microcalcifications in digital mammograms. The use of an empirically chosen wavelet and scale combination for detection of microcalcifications as an initial step of the CAD scheme has been reported by us previously. In this study, we developed a technique for optimizing the weights at individual scales in the wavelet transform to improve the performance of our CAD scheme based on the supervised learning method. In the learning process, an error function was formulated to represent the difference between a desired output and the reconstructed image obtained from weighted wavelet coefficients for a given mammogram. The error function was then minimized by modifying the weights for wavelet coefficients by means of a conjugate gradient algorithm. The Least Asymmetric Daubechies' wavelets were optimized with 297 regions of interest (ROIs) as a training set by a jackknife method. The performance of the optimally weighted wavelets was evaluated by means of receiver-operating characteristic (ROC) analysis by use of the above set of ROIs. The analysis yielded an average area under the ROC curve of 0.92, which outperforms the difference-image technique used in our existing CAD scheme, as well as the partial reconstruction method used in our previous study.