The optimization of boards by grades plays an important role in the production for cross cutting boards, and the outturn rate and utilization of boards are directly affected by the optimization results of boards by gr...The optimization of boards by grades plays an important role in the production for cross cutting boards, and the outturn rate and utilization of boards are directly affected by the optimization results of boards by grades. At present, the OptiCut series fully automatic optimizing cross-cut saw（FAOCCS） from Germany Weinig Group occupies the main markets in the world, but no report about the relative theories on the optimization technology and its algorithms is available. There exist some disadvantages in woodworking machinery and equipment used for cross cutting boards in China, for example, low sawing precision, outturn rate of boards and productivity, and difficulty in making statistics on the sawing results. Three optimization modes are presented for the optimization algorithms for FAOCCS, namely, optimization of fixed length, optimization of finger-jointed lumber and mixed optimization. Mathematical models are then established for these three optimization modes, and the corresponding software for realizing the optimization is prepared. Finally, Synthetic evaluation on the established mathematical models is presented through three practical examples. The results of synthetic evaluation indicate that FAOCCS using the optimization modes may raise the outturn rate of boards approximately 8% and the productivity obviously, and allows accurate statistics on the cross cut products of boards. The mathematical models of above three optimization modes are useful for increasing the outturn rate and utilization ratio of boards.展开更多
提出了一种用交叉模型交叉模态(Cross Model Cross Mode,CMCM)方法与L1正则化结合的损伤识别方法。首先介绍了CMCM方法的基本原理,以及L2正则化与L1正则化的特点。然后通过一个实验室的钢框架结构对提出的方法进行了验证。结果表明,CMC...提出了一种用交叉模型交叉模态(Cross Model Cross Mode,CMCM)方法与L1正则化结合的损伤识别方法。首先介绍了CMCM方法的基本原理,以及L2正则化与L1正则化的特点。然后通过一个实验室的钢框架结构对提出的方法进行了验证。结果表明,CMCM方法与L2正则化结合容易造成非损伤单元的误判,而在CMCM方法中使用L1正则化则能更准确地识别结构的损伤。即使仅用第一阶测量模态,用L1正则化技术求解CMCM方程也能很准确地识别框架结构的损伤。展开更多
现代谱估计方法能够反演基于几何绕射理论(geometric theory of diffraction,GTD)的模型参数,但不能处理非均匀不完备的雷达散射截面(radar cross section,RCS)数据。此外,通过暗室测量获取完备的RCS数据也需要较大的时空开销。针对上...现代谱估计方法能够反演基于几何绕射理论(geometric theory of diffraction,GTD)的模型参数,但不能处理非均匀不完备的雷达散射截面(radar cross section,RCS)数据。此外,通过暗室测量获取完备的RCS数据也需要较大的时空开销。针对上述问题,提出一种基于迭代加权最小二乘(iteratively reweighed least squares,IRLS)的跳频模式下GTD散射参数提取和RCS重构方法。该方法将稀疏重构理论与GTD散射模型相结合,能够在RCS数据非均匀不完备的条件下反演散射参数和实现RCS重构。仿真数据和电磁计算数据用于验证所提方法的有效性,实验结果表明该方法对降低暗室步进频率RCS的测量成本和扩增雷达RCS数据具有重要意义。展开更多
基金supported by Beijing Municipal Key Discipline Construction Project for Mechanical Design and Theory of China
文摘The optimization of boards by grades plays an important role in the production for cross cutting boards, and the outturn rate and utilization of boards are directly affected by the optimization results of boards by grades. At present, the OptiCut series fully automatic optimizing cross-cut saw（FAOCCS） from Germany Weinig Group occupies the main markets in the world, but no report about the relative theories on the optimization technology and its algorithms is available. There exist some disadvantages in woodworking machinery and equipment used for cross cutting boards in China, for example, low sawing precision, outturn rate of boards and productivity, and difficulty in making statistics on the sawing results. Three optimization modes are presented for the optimization algorithms for FAOCCS, namely, optimization of fixed length, optimization of finger-jointed lumber and mixed optimization. Mathematical models are then established for these three optimization modes, and the corresponding software for realizing the optimization is prepared. Finally, Synthetic evaluation on the established mathematical models is presented through three practical examples. The results of synthetic evaluation indicate that FAOCCS using the optimization modes may raise the outturn rate of boards approximately 8% and the productivity obviously, and allows accurate statistics on the cross cut products of boards. The mathematical models of above three optimization modes are useful for increasing the outturn rate and utilization ratio of boards.
文摘单电感双输出(single-inductor dual-output,SIDO)开关变换器工作在共享充放时序下存在电感电流纹波大、输出支路间交叉影响严重以及电路参数宽范围变化下控制电路不能正常工作等问题.为此,提出一种独立充放时序电流型变频控制(current-mode variable frequency control,C-VF)技术.首先,具体描述变换器在连续导电模式(continuous conduction mode,CCM)下的工作原理,并推导主电路开环传递函数;进一步构建闭环小信号模型,推导闭环交叉阻抗,详细分析不同输出电压及负载电流下变换器的交叉影响特性;最后,通过仿真和实验进行验证.研究表明:相较于共享充放时序,独立充放时序C-VF CCM SIDO buck变换器减小了交叉影响,改善了负载瞬态响应性能;当两支路负载电压不等时,减轻某一支路负载可以降低该支路的交叉影响;当两支路输出电压相同但负载不同时,重载支路对轻载支路的交叉影响更小.
文摘提出了一种用交叉模型交叉模态(Cross Model Cross Mode,CMCM)方法与L1正则化结合的损伤识别方法。首先介绍了CMCM方法的基本原理,以及L2正则化与L1正则化的特点。然后通过一个实验室的钢框架结构对提出的方法进行了验证。结果表明,CMCM方法与L2正则化结合容易造成非损伤单元的误判,而在CMCM方法中使用L1正则化则能更准确地识别结构的损伤。即使仅用第一阶测量模态,用L1正则化技术求解CMCM方程也能很准确地识别框架结构的损伤。
文摘现代谱估计方法能够反演基于几何绕射理论(geometric theory of diffraction,GTD)的模型参数,但不能处理非均匀不完备的雷达散射截面(radar cross section,RCS)数据。此外,通过暗室测量获取完备的RCS数据也需要较大的时空开销。针对上述问题,提出一种基于迭代加权最小二乘(iteratively reweighed least squares,IRLS)的跳频模式下GTD散射参数提取和RCS重构方法。该方法将稀疏重构理论与GTD散射模型相结合,能够在RCS数据非均匀不完备的条件下反演散射参数和实现RCS重构。仿真数据和电磁计算数据用于验证所提方法的有效性,实验结果表明该方法对降低暗室步进频率RCS的测量成本和扩增雷达RCS数据具有重要意义。
