贵金属分析取样理论中的泊松分布及计算选例

矿石分析取样，常有被测成份不均一问题，而贵金属分析中该问题尤其突出。通过仔细研究基础概率理论的柏松分布问题，能对取样理论作比较形象的，定量的理解。     

基于改进泊松-复合小波模型的复合地基全过程沉降预测

对复合地基全过程沉降预测模型与方法进行了研究.分析了改进泊松模型的特点和适用性,提出了改进泊松-复合小波神经网络修正模型.结合实际工程数据对CFG桩复合地基全过程沉降进行了分析和预测,并与改进的泊松模型进行了对比分析.结果表明,提出的模型适用性强,具有更高的预测精度,其绝对误差在1mm以内.     

基于改进微粒群优化的泊松曲线沉降预测模型

在现有文献研究的基础上,对泊松曲线沉降预测模型作了进一步的研究,给出了泊松曲线沉降预测模型的一个新方法-改进的微粒群最优化方法.该算法不需要计算梯度,容易应用于实际问题中.通过对微粒群算法的修正,使改进算法具有更加精确和快速的收敛性.经实例计算表明,这种方法具有较高的精度.     

基于EM算法的不完全疲劳寿命数据可靠性分析

针对随机截尾寿命数据模型的参数估计,提出基于EM算法的通用算法,并以疲劳寿命计算中所常用的二参数威布尔分布模型为例,给出基于EM算法的寿命数据拟合通用方法.另外对于服从复杂分布模型的数据,则采用与蒙特卡洛法相结合的EM算法.最后通过计算模拟的不完全疲劳寿命数据,验证了EM算法对于随机截尾寿命数据模型参数估计的有效性.     

两种非正态总体参数的区间估计

推导给出了两类非正态总体参数的区间估计,对二项分布的参数P和泊松分布的参数λ分别给出了其等尾双侧区间估计.     

基于泊松簇过程的三层异构蜂窝网络部署模型

5G标准下的蜂窝网络正在向异构化、超密集化的方向发展,传统的基于六边形网格模型的研究方法较为理想化且并不精确,越来越不适用于如今的异构网络.针对这个问题,目前常用的方法是使用基于随机几何的泊松点过程来研究异构网络的基站部署,这种方法假设基站的空域分布完全随机,因此得到了覆盖概率的理论下界.但是由于宏蜂窝边缘（盲区）以及热点地区（忙区）等特殊区域中,站点的分布可能形成簇,此时,基于泊松点过程的空域分布将不再准确.针对这个问题,本文使用泊松簇过程研究三层异构蜂窝网络的基站部署与规划.首先,提出基于泊松簇过程的基站部署系统模型,讨论了基于簇分布的基站形成过程;其次,在充分分析用户受到的聚集干扰基础上,采用基于瞬时信干噪比的小区选择机制,推导出了中断概率模型,并讨论了三种特殊条件下的中断概率;最后,通过仿真对比分析了基于泊松簇过程与泊松点过程的中断概率的差异以及信干噪比阈值变化时的中断概率的变化曲线,证明了基于簇的空域基站部署具有更低的中断概率.     

基于改进EM算法的氧化槽温控系统故障诊断

氧化槽是生物氧化提金的重要设备。在季节性强的中国西北地区,氧化槽温控系统运行在极端天气环境中不可避免会出现各类运行故障,若不及时排查会导致提金率的降低和矿产资源的浪费。针对此问题提出一种基于改进EM算法的氧化槽温控系统故障分类法,从而快速准确找出具体故障。仿真结果表明,改进EM算法能够充分利用工业大数据的优势,比传统EM算法与BP神经网络算法的分类正确率更高。     

一种基于AHP的海上待泊区动态编排算法

为保障海上安全形势稳定,提高船舶进出港交通效率,海上交通相关管理部门研究建立了待泊区并投入使用.待泊区的使用需要提前进行申请,海事局进行编排和调度.针对船舶待泊区申请的编排需求,提出了一种基于AHP的待泊区动态编排算法,首先确立待泊区编排算法的主要影响因素,并为各因素依次建立隶属度函数,结合采用AHP层次分析法确定各影响因素的动态权系数,进而得到综合隶属度函数值,从而完成待泊区申请的动态智能编排,大大提升了海上船舶的通航效率.该算法具有编排过程高效、编排结果精准等优点,还能应对编排因素多变的特点,结合各个港口的实际情况和独特特征,对不同影响因素进行个性化配置,大大提升用户体验.     

备件需求量的研究与建模

在备件ABC管理的基础上，分别进行了循环件需求量和非循环件需求量的建模，建立需求量计算的关系式，从而确定了备件的订货量，防止了备件的缺货和积压，实现了备件的最经济化管理。     

机械功能参数下可靠度的最大熵分布和贝叶斯估计

根据贝叶斯统计推断理论,提出了运用蒙特卡洛计算机模拟技术构造机械应力、强度功能参数下的可靠度最大熵先验分布的原理和方法.通过对圆柱形螺旋弹簧的可靠度计算实例分析,表明了这一方法具有机械工程实用价值,也为今后机械行业制定分布类型统一规范理论计算机械可靠度提供一种探索思路和理论方法.     

Estimation of Aquifer Parameters from Pumping Test Data by Genetic Algorithm Optimization Technique

Adequate and reliable estimates of aquifer parameters are of utmost importance for proper management of vital groundwater resources. The pumping (aquifer) test is the standard technique for estimating various hydraulic properties of aquifer systems, viz., transmissivity (T), hydraulic conductivity (K), storage coefficient (S), and leakance (L), for which the graphical method is widely used. In the present study, the efficacy of the genetic algorithm (GA) optimization technique is assessed in estimating aquifer parameters from the time-drawdown pumping test data. Computer codes were developed to optimize various aquifer parameters under different hydrogeologic conditions by using the GA technique. Applicability, adequacy, and robustness of the developed codes were tested using 12 sets of the published and unpublished aquifer test data. The aquifer parameters were also estimated by the graphical method using AquiferTest software, and were compared with those obtained by the GA technique. The GA technique yielded significantly low values of the sum of square errors (SSE) for almost all the datasets under study. The results revealed that the GA technique is an efficient and reliable method for estimating various aquifer parameters, especially in the situation when the graphical matching is poor. Also, it was found that because of its inherent characteristics, GA avoids the subjectivity, long computation time and ill-posedness often associated with conventional optimization techniques. Furthermore, the performance evaluation of the developed GA-based computer codes showed that the fitness value (SSE) of the best point in a population reduces with increasing generation number and population size. The analysis of the sensitivity of the parameters during the performance of GA indicated that a unique set of aquifer parameters was obtained for all three aquifer systems. The GA-based computer programs with interactive windows developed in this study are user-friendly and can serve as a teaching and research tool, which could also be useful for practicing hydrologists and hydrogeologists.     

EM73立式研磨机运行参数优化

以德国CLAUDIS PETERS技术公司生产的石油焦立式研磨机为例,介绍了立式研磨机结构及研磨原理,结合运行中的问题对立式研磨机进行性能的优化及技术改造,实现了低能耗、高效率。     

Simple Method for Quick Estimation of Leaky-Aquifer Parameters

Simple method and explicit equations are proposed for estimating the parameters of leaky aquifers from drawdown at an observation well, which avoid the curve matching or initial estimate of the parameter. The proposed method is computationally simple and the calculations can be performed even on a handheld calculator. The application of the methods is illustrated, using published data sets. The new method yields quick and accurate estimates of the leaky-aquifer parameters, if observed drawdowns do not contain large errors. The proposed method can also analyze the early drawdowns for accurate characteristics/parameters of a confined aquifer, if the conductance of the aquitard is assigned a zero value. It is hoped that the proposed method would be of help to field engineers and practitioners.     

Analytical Solution for Normal Irrigation Distribution Parameters

The model most widely used to represent sprinkler irrigation distribution parameters is based on numerical solutions to the normal cumulative probability density function. For most practical irrigation design and management applications, numerical solutions are too laborious. One other study reported analytical approximations for several irrigation distribution parameters derived from the normal model. The estimation error resulting from those approximations were variable over the operational range of irrigation uniformity and irrigation adequacy and were quite high in some ranges. In this note, more accurate analytical approximations are presented for the distribution coefficient, the application efficiency, the water requirement efficiency, the deficiently irrigated volume, and the average deficit over the deficiently irrigated area. On average, over the entire operational range of irrigation uniformity and irrigation adequacy, the new approximations are about an order of magnitude more accurate than the previous approximations and introduce negligible error for most practical applications.     

高精度OFDM信道估计算法

为了降低OFDM系统经典最小均方误差(MMSE)信道估计算法的误码率(BER),提出了经带阻滤波的MMSE信道估计算法.该算法首先采用MMSE得到初始的信道估计值,再利用离散傅里叶变换的特性,将噪声和信道频率响应信息分离开来,最后通过带阻滤波器对估计算法进行滤波,进而提高系统的BER性能.仿真结果表明,在增加少量计算复杂度的情况下,在导频间隔保持不变或逐渐增加两种情况下,所提算法的估计性能始终优于经典MMSE信道估计算法.     

Statistical Uncertainty and the Estimation of Log Law Parameters

It is experimentally demonstrated that fitting the log law to the mean velocity profile in turbulent open-channel flow to determine the friction velocity, roughness length, and zero-plane displacement, can lead to relatively high standard errors in these parameters. It is also demonstrated that this approach, where the log law alone is used to estimate these parameters, may yield values of these parameters that are significantly different from those obtained when the friction velocity is determined independently of the log law. Although the statistical estimation of the three log law parameters from mean velocity data alone is frequently necessary, this procedure can lead to inaccurate and imprecise estimates of these quantities.     

Experimental Investigation and optimization of Process Parameters for Shear Strength of Compound Cast Bimetallic Joints

Joining of A356 alloy and magnesium was carried out by vacuum assisted sand mold compound casting process. Microstructure at the joint interface was studied by using optical microscope, scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffractometer. Characterization indicated that a relatively uniform joint interface was obtained. The joint interface was composed of three distinct layers containing Mg₂Al₃ on aluminum side, Mg₁₇Al₁₂?+?δ eutectic structure on magnesium side and Mg₁₇Al₁₂ as middle layer. As a result of interaction between silicon, present in A356 with magnesium, Mg₂Si compound was formed. Push out test was conducted on electronics universal testing machine to measure the shear strength across the joint interface. The important process parameters (grit size of sand paper, insert temperature, pouring temperature and vacuum pressure) were optimized to maximize the shear strength. Optimization was carried out by using response surface methodology, desirability analysis and genetic algorithm (GA) techniques. It was observed that the shear strength increased by 14.21, 8.60 and 4.80% with genetic algorithm, desirability analysis and regression model respectively. GA reported the optimal value of shear strength.     

Numerical Studies of Estimation of Fracture Parameters for Mismatched Welded Joints with HAZ Cracks

An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone(HAZ).The fracture parameters Jand C*are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS.A middle crack tension(M(T))specimen is utilized in the analysis for different material properties and geometries of the weldment.The influence of mechanical property and geometry on the fracture parameters Jand C*of the specimen is discussed for the welded joints with HAZ crack.The results suggest that the HAZ property is a significant factor in the estimation of Jand C*for the mismatched welded joint with HAZ crack.     

Semianalytical Model for Shear Stress Distribution in Simple and Compound Open Channels

Semianalytical equations were derived for distribution of shear stress in straight open channels with rectangular, trapezoidal, and compound cross sections. These equations are based on a simplified streamwise vorticity equation that includes secondary Reynolds stresses. Reynolds stresses were then modeled and their different terms were evaluated based on the work of previous researchers and experimental data. Substitution of these terms into the simplified vorticity equation yielded the relative shear stress distribution equation along the width of different channel cross sections. In compound channels the effect of additional secondary flows due to the shear layer between the main channel and the flood plain were also considered. Comparisons between predictions of the model and experimental data, predictions of other analytical or three dimensional numerical models with advanced turbulent closures, were made with good agreement.