Effects of the number of benzene rings on the properties of single-source ZrC-based liquid precursors and nano zirconium carbide powders thereof

Effects of carbon source in single-source ZrC-based liquid precursors on the properties of the precursors and precursor-derived nano ZrC powders were investigated. The liquid precursors were prepared by directly blending and heating zirconium n-butoxide with either 2,4-pentanedione, benzoyl acetone or 1,3-diphenyl-1,3-propanedione additives which have the same chemical composition and structure except for the number of benzene rings (0, 1 and 2, respectively) in order to control the carbon content in the precursors. The ceramic yield of the precursor decreased as the number of benzene rings in the precursors increased. The stability of the precursors in air and the carbon content of the ceramic powder increased when using 1,3-diphenyl-1,3-propanedione additive. X-ray pure nano zirconium carbide powders with ultra-fine size (30 nm), isotropic shape and homogeneous particle size distribution were synthesized from the liquid precursors containing two benzene rings in the structure. Compared with ZrC powders derived from the precursors containing zero or one benzene ring, the powder from the precursor containing two benzene rings was finer and more homogeneous in size distribution.     

Analysis of color volume of multi‐chromatic displays using gamut rings

There are claims that multi‐chromatic displays can achieve a wider color gamut by the use of additional highly saturated secondary color channels. However, there are other claims that these displays lose lightness and/or color saturation at brighter levels. These apparently divergent views have led to some controversy in the display industry and at standard setting organizations. This study examines the color gamut volume for a variety of simulated and measured multi‐chromatic (sometimes incorrectly referred to as “multi‐primary”) displays using combinations of white and/or secondary color channels, such as cyan, magenta, and yellow. Furthermore, a two‐dimensional gamut representation, referred to as “gamut rings,” is introduced to illustrate that the addition of nonprimary optical color channels to a trichromatic (RGB) display can result in a significant decrease in the chroma at higher lightness levels. The additional saturated color channels can increase the gamut volume only around their hues at darker levels. The results also confirm the validity of comparing the color light output and white light output for revealing the design trade‐offs between the high‐peak white and the color‐image brightness for multi‐chromatic displays.     

考虑结构动态变形的缸套-活塞环润滑建模分析

缸套在燃烧冲击和活塞敲击激励下会产生接近表面粗糙度的动态变形,极有可能影响缸套-活塞环组件间的摩擦润滑过程。为了研究缸套动态变形潜在的影响,将动力学仿真获取的缸套内表面的动态变形经过处理后导入到润滑模型中,同时采用数值积分计算的方式对油液压力应力因子和剪切应力因子进行实时计算求解,使仿真计算更加符合实际情况。通过搭建同时考虑缸套变形与油液剪切特性影响的改进润滑模型,计算得到整个工作循环内活塞环上的最小油膜厚度和摩擦力曲线。结果表明:考虑缸套动态变形后的最小油膜厚度和摩擦力曲线出现了明显的波动,而且考虑缸套动态变形后的摩擦力比未考虑之前出现了明显下降。     

球罐法兰焊缝损坏的特殊修复方法

多晶硅生产工艺中,盛装氯硅烷球罐本体上的法兰焊缝损坏,在无法将设备内部的氯硅烷彻底置换干净的情况下,应用简易制作的活塞杆塞进法兰短接处,起到密封作用,在保证洁净度的前提下,使设备内部与需修复的法兰焊缝处完全隔离,通过动火分析合格后,对损坏的焊缝进行修复,确保了设备的安全运行,同时,对以后处理相类似的问题提供了借鉴。     

A novel adaptive convolutional neural network for fault diagnosis of hydraulic piston pump with acoustic images

As an essential part of hydraulic transmission systems, hydraulic piston pumps have a significant role in many state-of-the-art industries. Thus, it is important to implement accurate and effective fault diagnosis of hydraulic piston pumps. Owing to the heavy reliance of shallow machine learning models on the expertise and experience of engineers, fault diagnosis based on deep models has attracted significant attention from academia and industry. To construct a deep model with good performance, it is necessary and challenging to tune the hyperparameters (HPs). Since many existing methods focus on manual tuning and use common search algorithms, it is meaningful to explore more intelligent algorithms that can automatically optimize the HPs. In this paper, Bayesian optimization (BO) is employed for adaptive HP learning, and an improved convolutional neural network (CNN) is established for fault feature extraction and classification in a hydraulic piston pump. First, acoustic signals are transformed into time–frequency distributions by a continuous wavelet transform. Second, a preliminary CNN model is built by setting initial HPs. The range of each HP to be optimized is identified. Third, BO is employed to select the optimal combination of HPs. An improved model called CNN-BO is constructed. Finally, the diagnostic efficiency of CNN-BO is analyzed using a confusion matrix and t-distributed stochastic neighbor embedding. The classification performance of different models is compared. It is found that CNN-BO has a higher accuracy and better robustness in fault diagnosis for a hydraulic piston pump. This research will provide a basis for ensuring the reliability and safety of the hydraulic pump.     

往复式活塞压缩机中间喷液制冷系统的(火用)分析

通过对往复式活塞压缩机进行改造，在单级活塞压缩系统的基础上搭建了一种中间喷液冷却的准两级压缩系统并在蒸发温度为-20 ℃的工况下进行实验测量，根据实验数据对单级活塞压缩系统和新型中间喷液冷却活塞压缩系统的COP、〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失和〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗效率进行计算。结果表明：加入中间喷液冷却系统后，系统的COP由1.27提升至1.36，单位制冷量由155.1 kJ/kg提升至176.7 kJ/kg；单级活塞压缩系统〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失较大的部分是压缩机和膨胀阀，分别占压缩机输入〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗的16.2%和14.8%，加入中间喷液冷却系统后压缩机部分的〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损失明显降低，仅占压缩机输入〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗的3.6%，冷凝器及膨胀阀的〖HT5”，7”〗火〖KG-*3〗用〖HT5”〗损比也有所下降。     

基于液压活塞式惯容器的车辆悬架性能研究

阐述了液压活塞式惯容器的基本结构、工作原理与承载力大的特点，建立了考虑摩擦力、寄生阻尼力和油液弹性效应的惯容器非线性力学模型。在数控液压伺服激振台上对液压活塞式惯容器进行了力学性能试验，基于试验结果，利用Matlab参数辨识工具箱对非线性力学模型中的参数进行辨识。在此基础上建立了包含液压活塞式惯容器非线性因素的车辆惯容器 弹簧 阻尼器（inerter-spring-damper，简称ISD）悬架动力学模型并进行了仿真分析。结果表明，当考虑液压活塞式惯容器非线性因素时，车辆ISD悬架系统的车身加速度均方根值增加5%，而轮胎动载荷与悬架动行程均方根值均有所减小,降低了车辆的行驶平顺性。     

往复活塞式压缩机活塞杆温度高故障分析及改造

针对2台2D40型空气压缩机在实际试机过程中,活塞杆温度过高,导致连锁报警,压缩机不能正常工作的问题进行了详细的故障原因分析;对压缩机技术性能参数进行介绍;对压缩机的损伤情况进行说明并找到改造方案,解决机组运行中活塞杆温度过高的问题,从而提高机组的运行效率,使机组运行安全、稳定。     

一种考虑介质污染度的液压泵轴尾机械密封磨损的计算方法

为了准确计算液压柱塞泵机械密封的磨损,基于有限元方法提出一种考虑污染度水平和机械密封运动工况的磨损量计算方法。首先,针对单个磨粒模型建立机械密封表面的有限元模型,并基于实际工况进行仿真;然后对仿真和实验数据进行回归分析,确定单个磨粒造成的磨损量;最后研究介质中多种磨损颗粒对机械密封表面磨损的综合影响,提出一种考虑油液污染度的液压柱塞泵轴尾密封磨损的计算模型。通过对轴尾密封的表面观测结果,验证机械密封的磨损形式,并计算得出实际磨损量。通过对比基于提出的模型的解析结果与实际观测结果,证明提出的方法在计算含污染颗粒的机械密封磨损量时的有效性。     

旋转叶片电加热防冰系统设计与应用

在开展结冰试验时，结冰风洞风扇叶片前缘有结冰风险，影响风洞安全运行。针对大型旋转叶片结冰问题，提出了旋转叶片电加热防冰系统设计方法，研制了大型结冰风洞旋转叶片电加热防冰系统。首先，研制了内置电加热单元和温度反馈的防冰叶片。针对叶片复杂的工作环境，提出一种新的旋转叶片电加热防冰功率计算方法，通过精确测量和方案优化，设计了基于特殊环境的分半式、大尺寸、高线速度、碳刷自动移开/压紧的导电滑环。最后，采用变结构分级温度闭环和试验参数连锁防冰控制策略解决了旋转叶片结冰问题。该系统已应用于大型结冰风洞，运行中加热电流和叶片温度反馈信号传输连续，所有旋转叶片前缘快速加热且温度分布均匀，防冰效果好。