数控机床倍率信号的辨析与梯形图程序处理

在数控机床的编程、操作和调试与维修过程中,经常会遇到各种倍率信号,例如快速进给速度倍率信号、手动移动速度倍率信号、进给速度倍率信号等。详细叙述了FANUC—OiC数控系统的各种倍率信号的含义、有效方式、设定值计算和梯形图程序处理方法。     

基于PN的控制系统描述方法

介绍了一种基于PN的控制系统描述方法。通过将库所与输出和操作关联, 将变迁与输入和控制条件关联,该方法实现了对典型控制系统的有效描述。PN的库所和变迁能够表示为由输入、输出、操作和条件组成的逻辑表达式,该表达式可以方便地转化为PLC的LAD程序。在往复式运输系统中的应用实例表明该方法具有易于理解和修改的优点,能够极大提高PLC梯形图程序的设计效率。     

A statistical process control approach to business activity monitoring

Statistical Process Control (SPC) techniques have been successfully used in manufacturing industries to trigger and identify the root cause of variations so as to promote quality improvement. This paper develops a SPC framework to identify important changes deserved in business activity monitoring. To model and track thousands of diversified customer behaviors, the proposed SPC system consists of efficient and robust profiling methods to accommodate different behavior patterns including business changes, structural breakdowns, and unnecessary errors. Several customer profiling techniques are discussed and the activity monitoring performance based on the profiling algorithms is compared in a simulation example and a customer churn detection example in a telecommunications setting. The enhanced system will allow business managers and engineers to establish successful customer loyalty programs for churn prevention and fraud detection.     

Applying learning analytics dashboards based on process-oriented feedback to improve students' learning effectiveness

With the development of a technology-supported environment, it is plausible to provide rich process-oriented feedback in a timely manner. In this paper, we developed a learning analytics dashboard (LAD) based on process-oriented feedback in iTutor to offer learners their final scores, sub-scale reports, and corresponding suggestions on further learning content. We adopted a quasi-experimental design to investigate the effectiveness of the report on students' learning. Ninety-four freshman from two classes participated in this research. The two classes were divided into the LAD group and the original analytics report (OAR) based on a product-oriented feedback group. Before the experiment, all the students took the prior knowledge assessment. After a semester's instruction, all the students took the post-test of the summative assessment. Results indicated that students in the LAD group experienced better learning effectiveness than students in the OAR group. LAD based on process-oriented feedback was also effective in improving the skill learning effectiveness of the students with low-level prior knowledge.     

梯形图转语句表的等效网络合并方法研究

目前常用梯形图转语句表方法有拓扑排序、二叉树、广义表、串并联归并等,但在梯形图编辑软件中难于直接同图形编辑的描述对应起来,编程难度也较大。为解决这些问题,提出了一种等效网络合并方法,采用一个矩阵和相关的PLC梯形图符号来描述一个梯形图,并用一种类似于电阻网络的合并算法来实现梯形图的合并,变成一个最简化的合并图,然后再从该合并图生成语句表。该方法在编辑软件中梯形图的描述与转语句表运算采用完全相同的数据结构,并可从编辑软件中动态绘制梯形的合并过程,具有直观、易于理解、易于编程等优点。     

LAI retrieval from multiangular image classification and inversion of a ray tracing model

A non-conventional approach for the estimation of leaf area index (LAI) and leaf angle distribution (LAD), based on the use of information contained in multiangular images and the inversion of a canopy ray tracing model, is proposed in this work. As an alternative to the use of overall image reflectance data, the image fraction components, i.e. sunlit and shaded leaves and soil, are obtained by supervised classification of ground-based multiangular images acquired using an inexpensive colour infrared camera, the Dycam ADC. These data are used for the inversion of a numerical model of a vegetation canopy in which the latter is described as composed of randomly distributed disks (leaves). The model was developed using the POV-ray ray tracer. Model inversion is carried out using the look-up-table approach. The proposed methodology was tested using an extensive data set gathered on the potato crop during experimental trials carried out at Viterbo (Italy) for 3 years. The results show that LAI was successfully estimated with a RMSE varying from 0.29 to 0.75 in the different years. The potential sources of error in both estimated and measured LAI values are extensively discussed.     

硅烷偶联剂与TATB分子间相互作用的理论研究

利用密度泛函理论LDA/PW方法对γ-氨基丙基三醇硅烷(KH5501)偶联剂和1,3,5-三氨基-2,4,6-三硝基苯(TATB)分子间相互作用及其偶联机制进行了理论研究。结果表明硅烷偶联剂与TATB分子间的相互作用,改变了TATB分子的平面结构,增强了TATB分子的C—NO2键强度,降低了TATB分子的光热稳定性。另外,计算结果还表明硅烷偶联剂羟基上的氢与TATB硝基上的氧之间形成的氢键作用是硅烷偶联联剂与TATB发生偶联作用的主要形式,这一结论与实验预测结果一致。     

高功率激光焊接汽车用高强钢B450LAD组织与性能

采用15 kW CO3激光器对1.8 mm厚的热镀锌薄板B450LAD进行了高功率激光焊接.对工艺优化后所得到的4组焊接工艺规范参数的焊接接头进行宏观与微观组织分析、显微硬度试验以及拉伸力学性能试验.结果表明,在激光功率5.8～12.9 kW以及焊接速度3～7 m/min参数下,1.8 mm厚13450LAD镀锌钢板均可获得成形良好、无缺陷的焊缝;焊缝截面呈上宽下窄的倒梯形,热影响区(HAZ)相当窄;焊缝熔化区组织均为马氏体、细晶区组织为少量马氏体和铁素体;其焊缝中心显微硬度约为母材(BM)的2倍;焊接接头具有良好的拉伸力学性能,且4种拉伸试样均断于母材处.实验的4组工艺参数可作为此钢材不同应用场合下高功率激光焊接的工艺参考.     

粉料气力输送装置的PLC控制系统设计

针对脉冲式粉料气力输送装置工艺控制的特点,按照工艺控制要求、PLC控制时序图、PLC梯形图、控制原理图、仪表选型和PLC的I/O接线图的设计路径,阐述了一套基于PLC的程序控制系统设计方案。实践证明该控制系统经济可靠,性能良好。