Data-driven physical law learning model for chaotic robot dynamics prediction

Applied Intelligence - A robot control system is a multivariable, nonlinear automatic control system, as well as a dynamic coupling system. To address the difficult problem of data prediction under...     

面向国产平台的LLVM自动向量化移植与优化

作为SIMD扩展部件向量化的重要手段,自动向量化已在LLVM编译器中得到实现,但向量长度以及指令集功能的差异,导致国产平台在自动向量化过程中容易错失向量化机会以及向量化后产生倒加速的问题。为使SIMD得到充分应用,结合国产平台的指令集特征完善指令代价信息以提高收益分析精准度,使其在自动向量化后生成后端支持且简洁高效的向量指令。在此基础上,提出一种改进的控制流向量化方法,通过添加指令代价信息提高自动向量化的适配能力,从而形成一套面向国产平台的LLVM自动向量化系统。实验结果表明,相比自动向量化移植前,通过该方法进行移植优化后,SPEC测试的整体性能提升10.8%,TSVC测试集中的加速比提升16%,精准代价指导下的加速比提升42%,控制流向量化下的加速比提升51%。     

可控震源重锤-活塞杆动态行为规律与扰动控制研究

针对工程应用中可控震源振动器扰动量大、信噪比低等问题,结合重锤运动轨迹检测试验,通过理论计算与数值模拟,开展了重锤-活塞杆动态行为规律研究;在此基础上,开展振动器扰动控制研究,提出竖直进油方式振动器,与横向进油时的结果开展对比仿真分析,并进行竖直进油振动器扰动试验验证。结果表明:横向进油方式下,重锤受绕z轴的转动力矩作用且活塞杆存在变形,导致重锤上某点的运动轨迹为空间曲线,增大了振动器的扰动量,因此,横向进油方式是导致振动器扰动大的直接原因;竖直进油方式下,重锤不再受转动力矩影响且活塞杆变形得到极大改善,有效降低了振动器扰动量。研究结果对改善输出信号品质、提高输出信号分辨率具有重要的工程意义,建议在振动器的设计中采用竖直进油方式。     

我国农村废弃物分类资源化利用战略研究

本文围绕我国农村废弃物分类资源化利用问题,论述了农村废弃物的产生、危害以及资源化利用的重要意义,评估了我国农村废弃物的产生量、地区分布特征及资源化利用情况,深入分析了农村废弃物资源化利用存在的突出问题,结合美丽乡村建设及农村废弃物资源化利用的发展趋势,制定了农村废弃物资源化利用的发展战略及分阶段目标,提出了我国未来农村废弃物资源化开发利用的保障措施和政策建议。     

Preparation,characterization, and properties of disulfide-containing polyethyleneimine grafted carbon nanotubes

Novel functionalized carbon nanotubes (CNTs) were prepared by grafting disulfide-containing polyethyleneimine (SSPEI) to CNTs. The SSPEI were synthesized by Michael addition between cystamine bisacrylamide and low molecular weight branched 1.8 kDa PEI. Three SSPEI grafted carbon nanotubes (CNTs-SSPEI) were successfully prepared through grafting SSPEI to CNTs. The grafted ratios were 32.26%, 43.11%, and 51.50%, respectively. Moreover, the grafted ratio could be tuned by adjusting the CNTs/SSPEI ratio during the process of preparation. The CNTs-SSPEI was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The CNTs-SSPEI showed better dispersability and stability in water than CNTs. In addition, the SSPEI on the surface of CNTs-SSPEI could be degraded in the presence of dithiothreitol.     

Edge Fracture Prediction Using Uncoupled Ductile Fracture Models for DP780 Sheet

This paper is a contribution to the prediction of edge fracture behavior using uncoupled ductile fracture models. A fully integrated simulation framework for the edge fracture prediction is proposed with the shear-induced pre-damage considered. User-defined material subroutines are coded with uncoupled ductile fracture models (Lou-Huh, Oh, Brozzo) incorporated, which are calibrated using the fracture strains of various loading paths. A series of 3D numerical simulations are performed and compared with the results of hole-expansion tests. The effects of pre-damage field and fracture models are analyzed and discussed.

     

Displacement field denoising for high-temperature digital image correlation using principal component analysis

Principal component analysis (PCA) was extended to minimize the noise effect in digital image correlation (DIC) measurement under a high-temperature atmosphere environment. First, the principle of PCA was introduced, and the singular vectors and singular values for each component of the displacement fields from DIC were obtained. Then, the simulated high-temperature speckle images were developed to investigate the influences of noise on the DIC method under a high-temperature environment. Finally, the displacement fields of several special conditions were extracted from the simulated speckle images and experimental images; the effects of noise on the PCA were also analyzed.