Control of crankshaft finish by scattering technique

The paper describes a new sensor dedicated to measure and check the surface quality of mechanical products. The results were obtained comparing the light scattered from two different ranges of angles by means of 16 photodiodes. The device is designed for obtaining valid data from curved surfaces as that of a crankshaft. Experimental measurements show that the ratio between scattered and reflected light intensity increases with the surface roughness. This device was developed for the off-tolerance detection of mechanical pieces in industrial production. Results of surface quality on crankshaft supplied by Renault were carried out.     

氮离子注入钴烧结碳化钨的综合性能考察

本文对剂量为1.5×10~(17)、2.0×10~(17)和2.5×10~(17)Natoms/cm~2的3种氮离子注入钴烧结碳化钨表层的元素深度分布,显微硬度和摩擦学特性,以及氮离子注入改性的断续切削刀具之切削性能和使用寿命进行了考察,并就氮离子注入表面改性机理作了探讨。作者指出,钴烧结碳化钨经氮离子注入改性后可以减少1Cr18Ni9Ti不锈钢材料在干滑动摩擦时的粘附转移,并能使低摩擦力的摩擦初始段延长;适量的氮离子注入可以提高钻烧结碳化钨的表层硬度,而过量的注入却又会导致硬度下降;适量的氮离子注入可以减少钻烧结碳化钨刀具的切削刃部在使用过程度中的粘屑和崩刃,能够明显地提高刀具的切削性能和使用寿命。     

用人工神经网络计算机技术进行金刚石工具的摩擦学设计

在分析讨论了金刚石工具的摩擦学性能及其磨损机理之后，采用人工神经网络计算机技术编制了金刚石工具磨擦学设计的计算机程序，并且依据这种程序设计制造了一组铣磨轮，进而将其装机作了大理石材的磨削加工现场应用考察，结果表明，通过本程序设计可以使铣磨轮的平均消耗数减少１１％，磨削数率提高２８％，这是在采用人工神经网络计算机程序进行设计时，将实际工作数据作为神经元程序的学习和检查样本，它充分引入了现场使用状况对     

Modélisation du comportement thermique d'un outil de fraisage : approche par identification de système non entierThermal modelling of a milling tool: a noninteger system identification approach

In this work we present an experimental apparatus devoted to the thermal characterisation of a milling tool. The experimental device used thermistors, one for each insert. Each thermistor is located at a point in the tool close to the tip of the insert. The heat flux in each insert is expressed according to the temperature at the sensor from a non-integer model. The parameters of the model are identified from transient evolutions measurements of the temperature on the sensor and on the cutting edge. An application shows the difference in the behaviour of each insert during machining from the estimated heat fluxes. To cite this article: J.-L. Battaglia et al., C. R. Mecanique 330 (2002) 857–864.     

用MatLab曲线拟合工具箱处理物理实验数据

以测量玻璃热膨胀系数和折射率温度系数实验、太阳能电池基本特性测量实验为基础,介绍了用MatLab曲线拟合工具箱处理物理实验数据、拟合实验曲线的基本方法,展示了其简单、快捷、高效的特点。     

运动轨迹对抛光误差的影响分析和轨迹优化研究

针对现有光学加工抛光头运动方式由于光栅形或螺旋形等对称扫描方式带来的运动轨迹间的迭代误差,提出随机轨迹抛光运动方式.随机轨迹方法通过随机轨迹算法随机生成镜面离散点的抛光顺序和抛光轨迹,采用随机轨迹驻留时间补偿方法控制镜面离散点的驻留时间,对各个点进行相应大小的材料去除.实验结果显示,随机轨迹方法产生的抛光运动轨迹表现为...     

井眼轨迹控制工具主轴载荷与造斜能力关系研究

井眼轨迹控制工具是随钻实时完成导向功能的一种导向式钻井工具. 在复杂工况下,主轴承受钻压、扭矩和偏置机构作用力等,十分复杂. 在课题组前期研究的基础上,对样机主轴的力学行为开展了进一步的研究,在建立主轴静力学模型的基础上,分析了工具外壳刚度、偏置机构安装位置等因素对主轴力学行为与造斜能力的影响规律. 研究发现,主轴下端偏转角、偏心机构作用力和最大截面弯矩会随着偏心位移增加呈线性增加;随着外壳刚度的增加和偏置机构安装的位置与上支撑轴承之间距离的增加,工具造斜能力也会增强;通过分析偏置机构安装位置和外壳刚度对主轴力学行为的影响规律发现,随着外壳刚度的增大和偏置机构安装位置与上支撑轴承之间距离的增大,主轴最大截面弯矩也会增大. 最后,给出了最佳的外壳刚度与偏置机构安装位置建议.     

MiC in Chemistry Curriculum at the University of Tartu: the current status

The introduction of MiC (Metrology in Chemistry) into the Chemistry Curriculum at the University of Tartu using a two-stage approach is described. As the first stage the topics of MiC are first touched at the beginning of the first analytical chemistry lecture course in the 3rd semester. The emphasis there is on the measurement uncertainty (MU) and its practical estimation (based on the ISO GUM approach). The main purpose of this is to make it clear from the beginning that MU is an integral part of any measurement and to enable the students to estimate MU in the laboratory courses of analytical chemistry (3rd and 4th semesters). As the second stage, MiC is treated in more detail in a dedicated course where also topics, such as reference materials, interlaboratory comparisons, standardization, quality management, accreditation, etc are covered. Received: 6 November 2001 Accepted: 6 December 2001     

OriC-ENS: A sequence-based ensemble classifier for predicting origin of replication in S. cerevisiae

DNA Replication plays the most crucial part in biological inheritance, ensuring an even flow of genetic information from parent to offspring. The beginning site of DNA Replication which is called the Origin of Replication (ORI), plays a significant role in understanding the molecular mechanisms and genomic analysis of DNA. Hence, it is paramount to accurately identify the origin of replication to gain a more accurate understanding of the biochemical and genomic properties of DNA. In this paper, We have proposed a new approach named OriC-ENS that uses sequence-based feature extraction techniques, K-mer, K-gapped Mono-Di, and Di Mono, and an ensemble classification technique that uses majority voting for the identification of Origin of Replication. We have used three SVM classifiers, one for the K-mer features and two more for K-Gapped Mono-Di and K-Gapped Di-mono features. Finally, we used majority voting to combine the prediction by each predictor. Experimental results on the S. Cerevisiae dataset have shown that our method achieves an accuracy of 91.62 % which outperforms other state-of-the-art methods by a significant margin. We have also tested our method using other evaluation metrics such as Matthews Correlation Coefficient (MCC), Area Under Curve(AUC), Sensitivity, and Specificity, where it has achieved a score of 0.83, 0.98, 0.90, and 0.92 respectively. We have further evaluated our model on an independent test set collected from OriDB, consisting of the sequences of Schizosaccharomyces pombe where we have seen that our model can predict the origin of replication efficiently and with great precision. We have made our python-based source code available at https://github.com/MehediAzim/OriC-ENS.     

小型化学实验室信息管理系统设计

一个实验室每时每刻都会产生大量的复杂信息,这些信息主要是一些测量、分析的数据,以及许多维持实验室运行管理的数据。每一个实验室为维护这些数据需要大量的人力和物力,而且效率低下,容易出错,不利于数据的快速科学分析。大规模实验室的管理则头绪繁多。解决这类问题的有效办法,就是引入LIMS-实验室信息管理系统。