An Investigation of the Relationship Between the Gaussian Process Model Parameters and Surface Area in Three Dimensions

In this paper, we study the relationship between the fitted parameters in a Gaussian process (kriging) model and the complexity of the resulting response surface. This study is done for models with one response and two input variables. An analytical calculation of surface roughness is used as a measure of the complexity of the response surface fit by the Gaussian process model. Our findings indicate that the size of the fitted model parameters as measured across different fits and data sets do not give indication as to the complexity of the surface. We do, however, show that the magnitude of each of the parameters in a single fitted model gives indication about the amount of variability in the direction of that fitted parameter. Copyright © 2015 John Wiley & Sons, Ltd.     

低压铸造技术:发展历程、研究现状和未来趋势

低压铸造成型技术是现代大型薄壁复杂构件整体精密制造的重要研究方向之一。介绍了低压铸造技术的发展历程,概述了目前低压铸造技术的研究进展,重点对低压铸造充型过程和铸件合金材料的研究现状进行了综述和分析,探讨了充型过程和铸件合金材料研究中存在的问题,并提出了今后需要重点研究的方向。     

热管真空灌装封装系统研制及参数优化

热管真空灌装封装技术是制作热管的关键技术。工业上运用广泛的方法是"沸腾排气法",但该方法存在质量控制精度差和真空度不足等缺陷。常见的热管封装技术为冷焊技术,但封装过程中容易导致真空破坏。针对这些不足,研制了一种热管真空灌装封装系统:利用真空泵使热管内部实现高真空,同时利用液压装置对热管实现封装;对系统灌装封装流程进行优化设计,基于MFC编制了远程控制程序;通过实验,对液压压力进行优化,得到了最佳运行参数。该系统克服了沸腾排气法和现有冷焊技术的不足,达到较好的生产效果。     

基于改进灰狼算法的啤酒灌装PID液位控制

目的 针对啤酒罐装液位控制存在的变负荷、多模态、PID参数整定难的问题,提出一种基于改进灰狼算法的PID参数整定方法,以提高啤酒生产的工作效率。方法 对灰狼算法进行改进,使用欧式距离变化率动态调整收敛因子,平衡算法的全局搜索能力;引入动态自适应权重因子,提高算法的优化速度和精度;与基本灰狼算法比较并用测试函数验证改进算法的性能。结果 仿真结果表明,改进后的灰狼算法在收敛速度和精度上提升效果显著;改进灰狼算法整定的PID参数的上升时间为1.9s,调节时间为5.12 s,超调量为3.78%。结论 与基本灰狼算法对比,改进灰狼算法对啤酒灌装液位PID参数进行整定,调节时间快,超调较小,可以更好地满足啤酒生产的控制要求。     

未知环境下移动机器人遍历路径规划

为提高未知环境下移动机器人遍历路径规划的效率,提出了一种可动态调节启发式规则的滚动路径规划算法.该算法以生物激励神经网络为环境模型,通过在线识别环境信息特征,动态调用静态搜索算法和环绕障碍搜索算法,有效减少了路径的转弯次数.引入虚拟障碍和直接填充算法,解决了u型障碍区域的连续遍历问题.最后通过仿真实验表明了该方法在未知复杂环境下的有效性.     

Development of a linear predictive model for carbon dioxide sequestration in deep saline carbonate aquifers

CO₂ injection into deep saline aquifers is a preferred method for mitigating CO₂ emission. Although deep saline aquifers are found in many sedimentary basins and provide very large storage capacities, several numerical simulations are needed before injection to determine the storage capacity of an aquifer. Since numerical simulations are expensive and time-consuming, using a predictive model enables quick estimation of CO₂ storage capacity of a deep saline aquifer. In order to create a predictive model, the ranges of variables that affect the CO₂ storage capacity were determined from published literature data. Correlations found in literature were used for other important parameters such as pore volume compressibility and density of brine. Latin hypercube space filling design was used to construct 100 simulation cases prepared using CMG STARS. The simulation period covered a total of 300 years of CO₂ storage. By using a least-squares method, linear and nonlinear predictive models were developed to estimate CO₂ storage capacity of deep saline carbonate aquifers. Numerical dispersion effects were considered by decreasing the grid dimensions. It was observed that a dimensionless linear predictive model is better than the nonlinear. The sensitivity analyses showed that the most important parameter that affects CO₂ storage capacity is depth. Most of the (up to 90%) injected gas dissolved into the formation water and a negligible amount of CO₂ reacted with carbonate.     

通用扫描线多边形填充算法

传统的扫描线多边形填充算法只适用于水平扫描线的逐行填充。文章提出通用扫描线多边形填充算法,该算法可以有效地解决任意间距、任意倾角的扫描线对多边形的填充问题。通用扫描线多边形算法采用了坐标变换、浮点数舍入策略等重要方法。顶点扫描线号是该算法中的核心概念。     

基于划分策略和填充曲线的抖动模式研究

抖动处理是计算机图形学和图像处理中的一项关键技术,抖动算法的好坏直接关系互图像打印质量的优劣,针对利用评价函数生成较大抖动模式比较困难的问题,提出了划分初始模式的方法,并渐进生成较大抖动模式,针对模式抖动中出现的边界赝象,引入填充曲线机制加以消除,实验表明,采用以上方法得到的结果比较令人满意。     

边缘模型基背景区的JPEG压缩方法研究

模型基编码是目前极富前途的低比特率图象压缩方法之一 ,而边缘模型基方法较之通常的模型基方法有更多的优点 ,正逐渐引起研究人员的注目 .在边缘模型基中 ,除去了图象中大部分高频分量的背景区 ,其灰度变化较缓慢 ,这些被去除了的空域 ,大小大约占整个图象的 10 % .为了能采用传统的 JPEG方法 ,对背景区进行静态压缩 ,提出了一种简易的基于 8× 8子块的直流分量激励区填充方法 .实验表明 ,用该方法得到的填充后的图象十分适合 JPEG压缩 ,且可以得到较高的压缩比 ,同时图象的主观质量也优于直接对未填充图象做 JPEG压缩 .     

The <Emphasis Type="Italic">B</Emphasis><Superscript><Emphasis Type="Italic">dual</Emphasis></Superscript>-Tree: indexing moving objects by space filling curves in the dual space

Existing spatiotemporal indexes suffer from either large update cost or poor query performance, except for the B ^x -tree (the state-of-the-art), which consists of multiple B ⁺-trees indexing the 1D values transformed from the (multi-dimensional) moving objects based on a space filling curve (Hilbert, in particular). This curve, however, does not consider object velocities, and as a result, query processing with a B ^x -tree retrieves a large number of false hits, which seriously compromises its efficiency. It is natural to wonder “can we obtain better performance by capturing also the velocity information, using a Hilbert curve of a higher dimensionality?”. This paper provides a positive answer by developing the B ^dual -tree, a novel spatiotemporal access method leveraging pure relational methodology. We show, with theoretical evidence, that the B ^dual -tree indeed outperforms the B ^x -tree in most circum- stances. Furthermore, our technique can effectively answer progressive spatiotemporal queries, which are poorly supported by B ^x -trees.