某铜矿主矿体采矿方法优化选择研究

针对某铜矿主矿体500 m水平西区域复杂难采矿体,提出了进路式上向分层充填采矿法、脉内凿岩出矿巷低分段空场小步距回采嗣后充填法及脉外凿岩出矿巷低分段空场小步距回采嗣后充填法三种可行开采方案,并对三种采矿方案的采场布置、采切工程、回采工艺等进行了详细的介绍。对比分析三种采矿方法的优缺点和技术经济指标,优选出进路式上向水平分层充填采矿法进行开采。该采矿方法回采过程中采用浅孔爆破,能较好地保护上盘不稳定含砂层,工人作业环境安全性高,且其采切比、贫化损失相对较低,出矿品位较高,综合效益明显。     

复合材料纤维铺放技术及其应用

本文介绍了复合材料纤维铺放技术的特征和优点，综述其发展历史和世界先进国家在航空航天及其他领域的应用情况，并对我国展纤维铺放技术研究进行了展望。     

燕山水库汛限水位动态控制方案研究

随着全球极端气候越发频繁、水资源时空分布更加不均,水资源供需矛盾日益加剧。为充分利用水库调控水资源能力和发挥工程效益,采用预蓄预泄法对燕山水库汛限水位进行动态控制方案研究,首先基于下游防洪安全,根据降雨与洪水预报信息,采取预蓄预泄方案确定汛限水位上限值;再基于大坝自身安全和水库超泄能力分析确定了主汛期与后汛期的最高汛限水位。与原汛限水位104.20 m相比,考虑洪水预报信息情况汛限水位可调整至104.77 m,考虑降雨预报信息时可调整至105.36 m。计算分析结果表明,调整后的动态汛限水位对大坝自身安全及下游防洪安全影响较小,提高了水资源可利用率,具有可实施性。     

A unified method for optimal arbitrary pole placement

We consider the classic problem of pole placement by state feedback. We offer an eigenstructure assignment algorithm to obtain a novel parametric form for the pole-placing feedback matrix that can deliver any set of desired closed-loop eigenvalues, with any desired multiplicities. This parametric formula is then exploited to introduce an unconstrained nonlinear optimisation algorithm to obtain a feedback matrix that delivers the desired pole placement with optimal robustness and minimum gain. Lastly we compare the performance of our method against several others from the recent literature.     

Curvilinear grids for WENO methods in astrophysical simulations

We investigate the applicability of curvilinear grids in the context of astrophysical simulations and WENO schemes. With the non-smooth mapping functions from Calhoun et al. (2008), we can tackle many astrophysical problems which were out of scope with the standard grids in numerical astrophysics. We describe the difficulties occurring when implementing curvilinear coordinates into our WENO code, and how we overcome them. We illustrate the theoretical results with numerical data. The WENO finite difference scheme works only for high Mach number flows and smooth mapping functions, whereas the finite volume scheme gives accurate results even for low Mach number flows and on non-smooth grids.     

A CCD–ADI method for unsteady convection–diffusion equations

With a combined compact difference scheme for the spatial discretization and the Crank–Nicolson scheme for the temporal discretization, respectively, a high-order alternating direction implicit method (ADI) is proposed for solving unsteady two dimensional convection–diffusion equations. The method is sixth-order accurate in space and second-order accurate in time. The resulting matrix at each ADI computation step corresponds to a triple-tridiagonal system which can be effectively solved with a considerable saving in computing time. In practice, Richardson extrapolation is exploited to increase the temporal accuracy. The unconditional stability is proved by means of Fourier analysis for two dimensional convection–diffusion problems with periodic boundary conditions. Numerical experiments are conducted to demonstrate the efficiency of the proposed method. Moreover, the present method preserves the higher order accuracy for convection-dominated problems.     

Derivation of the multisymplectic Crank–Nicolson scheme for the nonlinear Schrödinger equation

The Crank–Nicolson scheme as well as its modified schemes is widely used in numerical simulations for the nonlinear Schrödinger equation. In this paper, we prove the multisymplecticity and symplecticity of this scheme. Firstly, we reconstruct the scheme by the concatenating method and present the corresponding discrete multisymplectic conservation law. Based on the discrete variational principle, we derive a new variational integrator which is equivalent to the Crank–Nicolson scheme. Therefore, we prove the multisymplecticity again from the Lagrangian framework. Symplecticity comes from the proper discrete Hamiltonian structure and symplectic integration in time. We also analyze this scheme on stability and convergence including the discrete mass conservation law. Numerical experiments are presented to verify the efficiency and invariant-preserving property of this scheme. Comparisons with the multisymplectic Preissmann scheme are made to show the superiority of this scheme.     

参数化的Deslauriers-Dubuc插值小波——构造及图像编码性能分析

研究了采用提升构造具有任意偶数阶消失矩, 满足对称性, 且仅用一个自由参数表达的 Deslauriers-Dubuc (D-D)双正交插值小波. 首先,采用多相矩阵理论推导出了此类小波存在的条件; 然后,给出了对应小波滤波器和插值小波变换的构造算法. 采用算法具体构造了分别具有消失矩对(4, 2)、(4, 4)、(6, 2)以及(6, 4) 等4类一参数表达的D-D插值小波; 最后, 以自由参数为自变量, 根据编码增益准则, 优化设计了4种用于图像编码的插值小波, 其滤波器系数全为二进制分数, 可实现非乘法运算的离散小波变换(Discrete wavelet transform, DWT). 系统分析表明, 两种小波的压缩性能超过CDF-9/7小波, 对于纹理图像, PSNR增益达到0.44.dB, 并且计算复杂度可降低17%以上. 实验同时表明, 新小波的重构图像具有更好的主观可视质量.     

基于FPGA的高速数据存储系统优化设计

针对遥测系统数据记录装置中数据传输速率与存储速率不匹配的问题,提出Flash的并行存储方案,采用交替双平面的编程方式可以使得存储器的存储速率达到单片Flash最高存储速率的2倍,即60 MB/s;对控制单元FPGA内部双端口RAM的逻辑设计进行改进,解决了数据存储异常的现象。在数据回收方面,提出了多备份的设计思想和备用读数接口的设计方案,已在工程应用中得到成功实践,验证了该数据记录装置的可靠性。     

Single-machine parallel-batching scheduling with family jobs to minimize weighted number of tardy jobs

We consider the problem of scheduling n jobs in batches on a single parallel-batching machine, where the jobs are partitioned into jobs families and the jobs in each family have the same due date. The objective is to minimize the weighted number of tardy jobs. We first devise an efficient pseudo-polynomial time and a fully polynomial time approximation scheme for the weighted problem. Then we present $O(n^2)$-time and $O(n\log n)$-time algorithms for the case where the jobs have the same weight and for the case where the jobs have the same processing time, respectively.