Comparison of quantification strategies for one-point standard addition calibration: The heteroscedastic case

Two quantification strategies for one-point standard addition calibration have been compared mathematically. One strategy involved the extrapolation of measurement points to their intercept with the x-axis to determine the analyte content in the unknown sample, and the other strategy is based upon direct calculation of the analyte content in the unknown sample using the instrumental responses obtained during measurement. The cases of both conventional standard addition calibration (C-SAC) and sequential standard addition calibration (S-SAC) have been considered. The heteroscedastic situation has been considered, where the relative precision of instrumental responses is constant.     

Indices for the evaluation of wildfire spread simulations using contemporaneous predictions and observations of burnt area

Methods to objectively evaluate performance are critical for model development. In contrast to recent advances in wildfire simulation, there has been limited attention to evaluating fire model performance. Information to validate fire models is typically limited, commonly to a few perimeter observations at a small number of points in time. We review metrics for comparing two burnt areas at a point in time: observed and predicted. These are compared in an idealised landscape and with a case study evaluating the performance of simulations of an Australian wildfire. We assessed: Shape Deviation Index (SDI), Jaccard's coefficient, F1, Sørensen's Similarity and Area Difference Index (ADI). For decomposing fit into error components (overprediction and underprediction) we assessed the partial indices of SDI and ADI, Precision and Recall. The various metrics were evaluated for their ability to represent error and their suitability for use in model improvement frameworks.     

Controlled material removal mode and depth of micro cracks in precision grinding of fused silica – A theoretical model and experimental verification

A critical function for crack propagation for the single grit scratching of fused silica is developed based on the fracture mechanics. The effects of original crack density on the surface, strain rate and grinding coolant are considered in the function. A theoretical model for controlled material removal mode and depth of micro cracks precision grinding is presented based on the critical function for crack propagation. It can be predicted by the model that the material removal mode in the grinding of fused silica with original cracks damage will change from a ductile mode to a semi-brittle mode, a full-brittle mode and a semi-brittle mode in sequence with the increasing single grit scratching depth. It was found that the micro crack damage depth of fused silica does not increase with the single grit scratching depth after a full brittle mode grinding and it is always smaller than that after a semi brittle mode grinding even with a smaller single grit scratching depth. These interesting results are explained by the fracture mechanics. The ductile mode grinding is a recognized desirable process of fabricating fused silica while the full-brittle grinding is also a feasible process for its shallow subsurface damage, high efficiency, low grinding force and energy consumption. Therefore, the depth of micro cracks after grinding can be controlled by choosing suitable grinding parameters. Grinding experiments are conducted on fused silica. The undeformed chip thickness of randomly distributed effective grits is simulated based on 3D reconstruction of wheel topography to reveal the relationship between the grinding parameters and the single grit scratching depth. Ground surface roughness, sub-surface damage (SSD) depth and grinding force are measured and discussed. It is shown that the model predictions correlate well with the experimental trend of grinding modes.     

棒材短应力轧机快速精准维修法

主要介绍了棒材短应力轧机的快速精准维修方法，阐述了该标准维修工序的形成、应用以及在标准工序过程中自主创新的先进工具，多项工具已申报实用性技术专利，该方法可提高产品质量，希望对类似工程有参考价值。     

热镀锌生产线中浴装机器气刀精度调整的研究

热镀锌生产线中浴装机器（ YG设备）的气刀装置精度是决定镀锌工序的关键因素，对整个镀锌板材产品质量具有重要意义。本文研究了气刀装置精度调整的方法，通过解体控制优化、气刀喷嘴开口度优化、气刀平行度控制优化以及气刀升降位置优化，使镀锌板上气刀痕迹显著减少，从而提高镀锌板产品的质量。     

Opportunities for control engineering in arable precision agriculture

In this paper, we present an overview of several challenges in arable farming that are well suited for research by the control engineering society. We discuss the global needs that these challenges are related to as well as the relation of these challenges to future applications of arable farming. For each of these opportunities we provide several concrete and detailed research questions. Particular attention is paid to the management of resources and sensors in farms. The objective of writing this paper is to further entice control engineers into the domains of agronomy and agricultural technology.     

Nanomechanical characterization of RB-SiC ceramics based on nanoindentation and modelling of the ground surface roughness

Reaction bonded silicon carbide (RB-SiC) ceramics are the primary structure and mold materials for the optical industry and mostly are machined by means of ultra-precision grinding to achieve a satisfactory surface quality. However, it is not easy to attain the theoretical prediction of surface quality, particularly surface roughness, because of different mechanical characterization of Si/SiC phases inside the RB-SiC ceramics. In this work, the nanoindentation tests were performed to investigate the nanomechanical characterization of individual phase inside the RB-SiC ceramics. On the basis of the nanoindentation results of RB-SiC, a theoretical model was established to predict surface roughness in the ultra-precision grinding process, which considered the different removal mechanisms of Si matrix and SiC particles. The comparison of the prediction results of existing and novel models and single-factor experimental results shows that the novel model was well consistent with the experiment.     

Efficient and precise cutting of zirconia ceramics using heated cutting tool

The thermally assisted machining of yttria-stabilized tetragonal zirconia polycrystal using a cutting tool heated with induction heating was proposed. Although the conventional thermally assisted machining cannot be applied to drilling, the proposed method can be. Heat transfer from the heated cutting tool to the workpiece was simulated analytically, and the result showed that heating of the tool up to 500 °C produced an increase of 150–400 °C in the workpiece temperature. Cutting experiments demonstrated an improvement in machinability.     

国产热模锻压力机的创新研究及应用选型

重点介绍了本公司热模锻压力机的最新研究成果,以及热模锻压力机在精锻领域自动化批量生产中的应用优势,并论述了生产应用中的选型策略。     

卫星导航系统基四选星算法

随着卫星导航系统的发展,可见星数大大增多,为了减少接收机运算量,需选择可见卫星的一个子类。本文分析了卫星导航系统中N个4星最优分布与某4星最优分布中的k(k≤3)个卫星(共4N+k颗卫星)的联合分布GDOP值,并以此为基础提出了一类低复杂度近似最优的基四选星算法。该算法以经典的4星选择算法(最大体积法和四步选择法)为基础,通过多次迭代与部分执行,实现任意多于4星的卫星选择。仿真结果表明该算法与准优算法相比运算复杂度和GDOP值都更低。