Development of a probabilistic algorithm of surface residual materials on Si3N4 ceramics under longitudinal torsional ultrasonic grinding

Longitudinal torsional ultrasonic-assisted grinding (LTUG) is one of the main methods to achieve high-quality and high-efficiency machining of high-performance ceramic materials. However, it isn't easy to accurately characterize the three-dimensional (3-D) surface topography due to multiple random factors during LTUG. Aiming at the complex surface features caused by multiple random factors in the LTUG of Si3N4 ceramics, a probabilistic algorithm for the height of residual material on the surface (HRMS) in LTUG of Si3N4 ceramic was proposed, and the prediction model for the 3-D surface topography and 3-D surface roughness parameters of Si3N4 ceramics in LTUG was established by using this algorithm. Simulation and experimental results show that the prediction model of 3-D surface topography and 3-D surface roughness established by the HRMS algorithm can more realistically predict the general characteristics of 3-D surface topography in LTUG under different process parameters, and the error range of the 3-D surface roughness parameter is 0–14.07%, which realizes the high-precision and high-reliability prediction of the 3-D surface topography and 3-D surface roughness parameters of the Si3N4 ceramic under LTUG.     

Comparison of 3-breed rotational crossbreds of Montbéliarde,Viking Red,and Holstein with Holstein cows fed 2 alternative diets for dry matter intake,production, and residual feed intake

The objective of this study was to compare 3-breed rotational crossbred (CB) cows of the Montbéliarde, Viking Red, and Holstein (HO) breeds with HO cows fed 2 alternative diets for dry matter intake (DMI), fat plus protein production (CFP), body weight (BW), body condition score (BCS), feed efficiency, and residual feed intake (RFI) from 46 to 150 days in milk (DIM) during first lactation. The CB cows (n = 17) and HO cows (n = 19) calved from September 2019 to March 2020. Cows were fed either a traditional total mixed ration diet (TRAD) or a higher fiber, lower starch total mixed ration diet (HFLS). The HFLS had 21% more corn silage, 47% more alfalfa hay, 44% less corn grain, and 43% less corn gluten feed than the TRAD. The 2 diets were analyzed for dry matter content, crude protein, forage digestibility, starch, and net energy for lactation. The BW and BCS were recorded once weekly. Daily milk, fat, and protein production were estimated from twice monthly milk recording with random regression. Measures of efficiency were CFP per kilogram of DMI and DMI per kilogram of BW. The RFI from 46 to 150 DIM was the residual error from regression of DMI on milk energy, metabolic BW, and the energy required for change in BW. Statistical analysis of all variables included the fixed effects of diet, breed group, and the interaction of diet and breed group. The CB cows fed HFLS had less DMI (?12%) and lower DMI/BW (?14%) compared with the HO cows fed TRAD. For CFP, CB and HO cows were not different when fed TRAD or HFLS. Furthermore, the CB cows fed HFLS had higher BW (+50 kg) compared with HO cows fed HFLS. The CB cows fed TRAD had higher BCS than HO cows fed TRAD and HO cows fed HFLS (+0.46 and +0.62, respectively). The HO cows fed TRAD had more DMI (+14%) and lower CFP per kilogram of DMI (?12%) compared with the HO cows fed HFLS. In addition, mean RFI from 46 to 150 DIM was lower and more desirable for CB cows fed HFLS (?120.0 kg) compared with HO cows fed TRAD (85.3 kg). Dairy producers may feed either TRAD or HFLS to CB cows without loss of CFP.     

基于MSC的板材冷轧残余应力分布的数值仿真

利用MSC软件建立了轧制过程的力学模型,采用弹塑性大变形有限元法,对典型铝板材冷轧后的残余应力分布进行数值仿真。仿真结果表明,在压缩量较小时,板材表面是残余压应力,心部是残余拉应力,在压缩量较大时,表面为残余拉应力,内层则呈残余压应力,且分布不均匀,压缩量过大引起的残余应力的分布不利于板材的抗疲劳能力     

有色金属工业如何面向新世纪

在本地纪初，我国有色金属工业面临着新的国际环境和市场形势，应以市场为导向，提高经济效益，促进科技进步，加快结构调整，培育有国际竞争力的大型企业集团。     

湖北省大冶铁矿区内矿石磁性特征分析

从磁铁矿矿石的磁性差异入手,对铁(铜)矿床中各矿体的矿石磁性特征进行了系统的研究,得出大冶铁矿铁(铜)矿床是一个磁性特征变化较大的矿区,影响磁铁矿矿石磁性特征的主要因素为矿石的矿物组成、化学成分以及矿石的结构和构造。     

数控铣削加工程序通用模块化的实现

在合理安排工艺过程的基础上,如何编制结构简洁、刀路科学的数控程序很大程度上影响着工件加工效率和质量,探讨如何合理运用子程序和刀具半径补偿功能,实现数控铣削加工程序的模块化、通用化。     

磨料水射流切割机的数控系统

本文介绍了ＳＭＤ－１型两坐标数控磨料水射流切割机控制系统的软件设计及硬件配置。使用结果表明该数控系统具有简单、可靠、易操作、抗干扰性强等优点。不仅适用于磨料水射流切割机，也可用于其它类似加工设备的控制。     

CAD数据文件加密技术的剖析

考察了一个小型CAD系统,对其数据文件进行了剖析,导出其数据文件的详细构造,并依据其文件结构编写了一个数据解密的样例程序供参考。     

对“三下”采煤技术未来的思考

基于对"三下"采煤技术发展的认识,提出了充填开采是"三下"技术的发展方向,物理探测是保证水体下采煤的技术手段,采空区评价与处理是"三下"技术拓展的领域,并对各方面的技术研究重点做了阐述,以供"三下"采煤技术研究参考。     

安全投入非线性优化模型

文章利用非线性规划模型,在企业的安全事故控制在一定范围,即安全事故经济损失控制在一定范围的条件下,建立实现安全成本最小化的安全投入非线性优化模型,得出企业最优化安全投入总额和分项投入方案,解决了企业如何进行安全投入和安全投入多少的决策问题。