Nanotribological study of PECVD DLC and reactively sputtered Ti containing carbon films

Amorphous carbon film, also known as DLC film, is a promising material for tribological application. It is noted that properties relevant to tribological application change significantly depending on the method of preparation of these films. These properties are also altered by the compositions of these films. DLC films are well known for their self-lubricating properties, as well. In view of this, the objective of the present work is to compare the tribological properties of diamond like carbon (DLC) film obtained by plasma enhanced chemical vapour deposition (PECVD) with the Ti containing nanocrystalline carbon (Ti/a-C:H) film obtained by unbalanced magnetron sputter deposition (UMSD) in nN load range. Towards that purpose, DLC and Ti/a-C:H films are deposited on silicon substrate by PECVD and UMSD processes respectively. The microstructural features and the mechanical properties of these films are determined by scanning electron microscope (SEM), transmission electron microscope (TEM) and nano indenter. The surface topographies and the friction force surfaces of these films are evaluated by means of an atomic force microscope (AFM). The results show that although PECVD DLC film has higher elastic modulus and higher hardness than UMSD Ti/a-C:H film, the surface roughness and the friction coefficient of PECVD film is significantly higher than that of UMSD Ti/a-C:H film.     

数控超声磨削陶瓷叶片型面刀位轨迹计算

介绍了陶瓷超声磨削加工现状,建立了平行直纹面数学模型.分析了用圆柱磨轮四轴数控超声磨削平行直纹面时原理误差,并提出减小误差的措施,计算出磨轮空间轨迹,并进行陶瓷叶片型面超声磨削加工工艺试验.试验结果表明,超声磨削加工陶瓷叶片型面是可行的,所完成的刀位计算可有效减小原理误差.     

GM(1,1)模型在虚拟仪器测量过程控制中的应用

虚拟仪器的测量过程控制是保证测量数据有效的重要手段,利用灰色系统GM(1,1)模型对虚拟仪器的测量过程进行控制,由少量数据信息得到未来的预期测量结果,通过与核查标准的测量结果相比较来判别测量过程是否受控.论文给出了测量过程控制判别限、适用灰色系统GM(1,1)模型的条件以及模型精度检验判据.     

可调数学形态学的角点检测新算法

提出了一种新的基于可调形态学的角点检测方法。该方法采用对称圆形结构元素,通过选择合适的可调参数,对图像进行可调膨胀和可调腐蚀等一系列运算,先分别计算图像中凸角点和凹角点的精确位置,再将两者结合起来,从而得到图像中的所有角点。利用圆形结构元素大幅度减少了算法的计算量。可调形态学的应用克服了传统形态学检测角点不准确的缺点。实验结果证实了当可调算子中的参数取合适值时,该方法可以较精确地检测出图像中的角点位置。     

Synthesis and characterization of LiNi0.95-xCoxAl0.05O2 for lithium-ion batteries

Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-DTA, XRD, SEM, and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially, 5 at.% A1 and 10 at.% Co） definitely had a large beneficial effect in increasing the capacity （186.2 mA.h/g of the first discharge capacity for LiNio.s.42OoaoAlo.0502） and cycling behavior （180.1 mA-h/g after 10 cycles for LiNio.85CooaoAlo.osO2） compared with 180.7 mA.h/g of the first discharge capacity and 157.7 mA.h/g of the tenth discharge capacity for LiNiO2, respectively. Differen- tial capacity versus voltage curves showed that the co-doped LiNio.95_xCoxmlo.osO2 had less intensity of the phase transitions than the pristine LiNiO2.     

Development of a noise prediction software NASEFA and its application in medium-to-high frequency ranges

For the analysis of noise problems in medium-to-high frequency ranges, the energy flow boundary element method (EFBEM) has been studied. EFBEM is numerical analysis method of energy flow analysis (EFA), and solves energy governing equations using a boundary element method in complex structures. Based on EFBEM, a noise prediction software, “noise analysis system by energy flow analysis” (NASEFA), was developed. For effective maintenance, NASEFA is composed of three main modules: the translator, the model converter, and the main solver. The translator changes the FE model to the NASEFA BE model, and the model converter changes the BE model to an EFBE model, including various data, such as structural materials, medium properties, sources, and boundary conditions. NASEFA then solves the acoustic energy density and intensity on boundary and in the field. Moreover, it analyzes interior and exterior noise problems for single and multiple domains in two and three dimensions. Finally, for the validation of the software developed, interior and exterior noise predictions of various structures were performed. The results obtained with NASEFA were compared with those of the commercial SEA program and experiment. From these comparative studies, the usefulness of NASEFA was established.     

Multi-objective flexible job shop schedule: Design and evaluation by simulation modeling

Flexible job shop schedule is very important in both fields of combinatorial optimization and production management. In this paper, a simulation model is presented to solve the multi-objective flexible job shop scheduling problem. The proposed model has been coded by Matlab which is a special mathematical computation language. After modeling the pending problem, the model is validated by five representative instances based on practical data. The results obtained from the computational study have shown that the proposed approach is a feasible and effective approach for the multi-objective flexible job shop scheduling problem.     

基于龙伯格观测器的BLDC滑模控制系统仿真研究

针对无刷直流电机（BLDC）负载频繁改变导致电机调速性能差的问题,提出了一种基于负载转矩观测器的速度滑模控制方法。速度环采用滑模变结构控制方法,基于改进指数趋近律设计了速度滑模控制器;同时为了减小负载转矩扰动对电机运行状态的影响,基于龙伯格观测器设计了负载转矩观测器,通过观测器来估计实际的负载转矩并将观测器的输出前馈给速度滑模控制器来抵消负载转矩扰动的影响。为了验证提出方案的有效性,在MATLAB/Simulink仿真环境上搭建了仿真模型并进行了仿真分析,仿真结果表明基于负载转矩观测器和速度滑模控制器的无刷直流电机系统有着优异的性能,与传统PI控制相比,抗扰能力强、恢复时间短、转速响应快,证明了提出方案的有效性。     

Efficient skeleton curve-guided five-axis sweep scanning based on optimal traversing of multiple connected skeleton curves

The five-axis sweep scanning approach is an emerging surface inspection technology which could tremendously boost the inspection efficiency through working in the way of continuous scanning. While inspecting the surfaces with multiple connected skeleton curves, the topological complexity brings conflict between achieving efficient inspection and working in continuous manner. Recently, a skeleton curve-guided five-axis sweep scanning method was proposed to tackle this problem but the resulting inspection path has to inspect the entire surface in a round-trip way. The manner of round-trip inspection pulls down the entire inspection efficiency and should be avoided as much as possible. In this paper, we present an improved skeleton curve-guided five-axis sweep scanning method to generate a more efficient five-axis scanning path for the surface with multiple connected skeleton curves. The proposed method starts from the framework of existing skeleton curve-guided five-axis sweep scanning method. Under the unique kinematic requirements of efficient five-axis sweep scanning, an integer linear programming optimization approach is utilized to optimally connect the inspection paths on independent surface patches and form a shorter skeleton curve-based sweep scanning path as compared with the existing skeleton curve-guided five-axis sweep scanning method. The resulting inspection path is composed of the single-pass inspection for most of the surface and the round-trip inspection for a small part of the surface. The comparison experiments are conducted on two surfaces with multiple connected skeleton curves. Experiment results show that the proposed method significantly outperforms the method provided by the leading commercial software Apexblade and the original skeleton curve-guided five-axis sweep scanning method.