FO-CA:一种基于距离差异度组合权重的多属性数据分类方法

为了解决多属性数据分类问题,提出了一种基于模糊优选模型与聚类分析的分类方法(FO-CA)。首先由模糊优选模型得到有序综合指标数据集,其中在权重阶段提出了距离差异度并以此为依据构建了一种组合主客观权重的赋权方法;然后采用聚类分析将有序综合指标数据集聚类为几个簇进而分类;最后选取UCI中的Iris、Wine和Ruspini 3个数据集进行仿真实验。实验结果表明,该分类方法相比模糊优选方法及K-Means算法能获得更好的分类结果,对决策者有一定的参考价值。     

资源受限项目调度问题的改进文化微粒群算法求解

为了克服标准微粒群算法在求解资源受限项目调度问题上存在的早熟现象,提出一种改进的文化微粒群算法。该算法框架基于微粒群算法的主群体空间和文化算法的知识空间,两种空间具有各自的群体并可独立并行演化,形成双演化双促进机制,提高了算法的全局搜索能力和运行效率。同时为了避免文化算法知识空间自我演化限制,引入遗传算法的演化机制来改进知识空间的演化操作。通过具体的算例比较,验证了提出的改进文化微粒群算法在求解资源受限项目问题时的有效性。     

Investigation of Barree-Conway non-Darcy flow effects on coalbed methane production

Coalbed gas non-Darcy flow has been observed in high permeable fracture systems,and some mathematical and numerical models have been proposed to study the effects of non-Darcy flow using Forchheimer non-Darcy model.However,experimental results show that the assumption of a constant Forchheimer factor may cause some limitations in using Forchheimer model to describe non-Darcy flow in porous media.In order to investigate the effects of non-Darcy flow on coalbed methane production,this work presents a more general coalbed gas non-Darcy flow model according to Barree-Conway equation,which could describe the entire range of relationships between flow velocity and pressure gradient from low to high flow velocity.An expanded mixed finite element method is introduced to solve the coalbed gas non-Darcy flow model,in which the gas pressure and velocity can be approximated simultaneously.Error estimate results indicate that pressure and velocity could achieve first-order convergence rate.Non-Darcy simulation results indicate that the non-Darcy effect is significant in the zone near the wellbore,and with the distance from the wellbore increasing,the non-Darcy effect becomes weak gradually.From simulation results,we have also found that the non-Darcy effect is more significant at a lower bottom-hole pressure,and the gas production from non-Darcy flow is lower than the production from Darcy flow under the same permeable condition.     

基于弯矩影响面方法的单向板移动荷载最不利位置研究

采用影响面的方法,运用matlab数值分析软件对移动荷载下板的弯矩变化进行了模拟分析。通过控制板的长短边比例,得出不同工况下移动荷载的最不利位置,同时对影响最不利位置的因素进行了相关的模拟研究,得出了长宽比越大的板,其受移动荷载的影响越小的结论。对今后具体的工程计算具有一定的参考意义。     

PIBSI对油基钻井液性能影响研究

常温条件下分别采用5号和3号两种白油配制基浆和油基钻井液体系,并在基浆和钻井液体系中加入不同质量分数的聚异丁烯丁二酰亚胺(PIBSI),考察不同温度下PIBSI的质量分数对基浆和钻井液体系流变、沉降和滤失性能的影响。结果表明,对于基浆而言,低温条件下(4℃)PIBSI能够提高基浆的沉降稳定性能,基浆的黏度随PIBSI质量分数的增加先降低后增加。对于油基钻井液体系而言,在适当质量分数下(5号白油体系PIBSI质量分数为2%,3号白油体系PIBSI质量分数为0.2%),PIBSI能够有效降低体系低温条件下(4℃)的黏度,而对室温(25℃)和高温(65℃)条件下体系的黏度、动切力等参数影响程度较小。PIBSI质量分数越高,两种油基钻井液体系的高温高压降滤失量越低。     

Automotive fuel cell sloshing under temporally and spatially varying high acceleration using GPU-based Smoothed Particle Hydrodynamics (SPH)

Understanding how fuel sloshes in a fuel cell, as a vehicle races around a circuit, is an important but mostly unexplored factor when designing fuel containment systems. Cell designs are based on knowledge of how liquids slosh in other containers, with the design and placement of structures, such as weirs, based on engineering judgement.This work aims to provide better understanding for this difficult problem with a view to improve future designs. A Graphics Processing Unit (GPU) based Smoothed Particle Hydrodynamics (SPH) model is presented to simulate the fuel sloshing problem, with results from a simplified and real fuel cell geometry shown and compared against real data recorded in a vehicle. The vehicle motion and accelerations are included in the SPH simulations using a body force within the momentum equation. Results show good agreement between the simulation and the real fuel movement, with bulk motion captured well for accelerations up to 5 times gravity.Focus is placed on the practicality of the method for use as part of an industrial design process, therefore the amount of time needed to compute results is considered throughout. Computational performance is found to be within acceptable limits, while numerical accuracy is actively considered through the use of Kahan compensated summation. It is concluded that the model is successful in capturing the necessary fluid dynamics for it to be useful in fuel cell design. It is expected that the method will provide insight into current cell designs and highlight where improvements can be made.     

一种基于项目属性评分的协同过滤推荐算法

协同过滤是电子商务推荐系统中应用最成功的推荐技术之一,但面临着严峻的用户评分数据稀疏性和推荐精度低等问题。针对数据稀疏性高和单一评分导致的推荐精度低等问题,提出一种基于项目属性评分的协同过滤推荐算法。首先通过均值法或缩放法构造用户-项目属性评分矩阵将单一评分转化为多评分;其次基于每个属性评分矩阵,计算用户间的偏好相似度,得到目标用户的偏好最近邻居集;然后针对每个最近邻居集,在用户-项目评分矩阵上完成对目标用户的初步评分预测;最后,将多个初步预测评分加权求和作为综合评分,完成推荐。在Movie Lens扩展数据集上的实验结果表明,该算法能有效提高推荐精度。     

永磁同步电机模糊PID控制建模与仿真

永磁同步电机（PMSM）作为一种非线性、强耦合、参数时变的被控对象,传统PID对其控制效果欠佳。为此在PID的基础上,结合模糊控制的优点,设计了一种PMSM的模糊自适应PID控制策略,并对系统建模仿真。结果表明,与PID控制相比,该模糊PID控制方案具有自适应强、超调量小等特点。