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61.
为了能实现对轻、薄、小物料的稳定输送,提出了一种压电双晶片为驱动源配重式直线振动输送器。设计了压电振动输送器的结构并分析了其工作原理,建立了系统的动力学模型,推导出了双自由度系统的振动位移表达式以及近似得到系统的固有频率,制作了振动输送器的样机,并进行了试验测试。试验结果表明:在系统共振频率为120.5Hz,料道振动位移达到最大,3个测试点分别为39μm,34μm,37μm,但不影响物料输送,工作频率范围为117~124Hz,处于共振频率最大输送速度达到52mm/s。与同型号的电磁式振动输送器相比,在共振条件下研制的样机的电流仅为电磁式的16.58%,速度是其1.36倍,振幅为电磁式的32.38%,噪音降低了33dB。设计的输送器具有送速度稳定、节能、噪音小等优点。 相似文献
62.
利用光学量子随机源中光子的随机性,设计了一种无需后处理的随机数产生器。在设计中,用弱光源进行单光子水平的探测,利用单光子水平的光源在半导体探测器上一定周期内探测到的脉冲个数服从泊松分布的基本原理,而元器件和读出电子学造成理想泊松分布的变形,通过控制平均计数消除偏差,达到统计学上的无偏。本设计具有自动纠偏功能,产生无后处理的高质量高速真随机数,并通过了NIST、Diehard等多种技术测试标准。 相似文献
63.
64.
采用双靶非反应磁控溅射,通过改变基底偏压,制备了一系列Ni掺杂TiB2基的涂层.通过X射线能谱仪确定其成分,利用X射线衍射、扫描电镜对涂层的结构进行分析,并通过纳米压痕、维氏压痕、划痕以及摩擦磨损分别对涂层的硬度、模量、断裂韧性、膜基结合力和摩擦学性能进行了表征.结果表明:此工艺下制备的TiB2-Ni涂层中均存在六方相的TiB2结构,并且生长结构非常致密,无明显的柱状生长结构,表面粗糙度低;硬度均大于40 GPa;涂层均具有较好的断裂韧性;且随着偏压增大断裂韧性和结合力都有所提高;同时所制备涂层摩擦系数均在0.5~0.6,磨损率在同一数量级. 相似文献
65.
针对水声信道中窄带信号的多途时延估计问题,本文在对复倒谱时延估计方法进行研究的基础上,提出了一种基于对数域同态滤波的时延估计算法.结合复倒谱与同态滤波思想,将接收的窄带信号首先变换到对数域,然后与本地存储的信号进行谱减法,再对相减后的信号进行滤波以消除残余的信号与噪声成分,最后将其恢复到时域以获取多途时延估计.与传统的匹配滤波/相关处理以及复倒谱分析方法相比,本文算法具有时延估计精度高、噪声抑制能力较强等特点.仿真与湖试数据处理结果证明了该方法的有效性. 相似文献
66.
NiCrBSi coatings with different Nb additions have been prepared by laser cladding. The microstructure, phase composition, hardness, and wear resistance of the coatings were studied by scanning electron microscopy (SEM), electron probe microanalyser (EPMA), X-ray diffraction (XRD), microhardness tester and M-200 wear tester. The results show that the phases in the NiCrBSi coating without Nb addition include γ-Ni, Cr23C6, Cr7C3, Ni3B, Ni3Si2 and CrB. The NbC phase appears in coatings after the addition of Nb element. When the addition of Nb is 2?wt-%, the NbC particles with a size of about 1.2?μm were found in the coating, and the amount of NbC is about 1.8?vol.-%. With the increase of Nb addition, the size and amount of NbC in the coatings also increased. When the addition of Nb is 6?wt-%, the size of NbC is about 2.3–6.1?μm and the morphology of NbC changed from particle to quadrangular and petaloid shaped. In addition, when the addition of Nb is 2?wt-%, the hardness and wear resistance of the coating are the best, and the wear resistance of the coating is 104% higher than that without Nb addition. 相似文献
67.
《中国有色金属学会会刊》2020,30(3):647-656
The AM50, AM50–0.1Ca, AM50–0.3Ca and AM50–0.5Ca (wt.%) alloys were hot-rolled and their mechanical properties were determined for the purpose of investigating the effect of trace Ca addition on the texture and stretch formability of AM50 alloy. The results show that the addition of trace Ca can effectively modify the basal texture, which is characterized by the split of basal poles deviated from the normal direction (ND) after the hot rolling, while a broad spread of the basal planes toward the transverse direction (TD) after the annealing. Such change of the basal texture is related to the prior formation of massive compression twins and the decrease of the c/a ratio. Erichsen value increases from 2.25 to 4.21 mm with the increase of Ca content. The enhancement of stretch formability is ascribed to the weakened basal texture, which results in the increase of n-value and the decrease of r-value. 相似文献
68.
Mengting Guo Chongyun Shao Yang Zhang Jingbo Yu Yan Jiao Malgorzata Guzik Georges Boulon Jinjun Ren Lili Hu 《Journal of the American Ceramic Society》2020,103(8):4275-4285
The homogeneous Yb3+/Al3+/B3+-co-doped silica glasses were prepared via a sol-gel method. The impact of B2O3 addition on the physical and optical properties and network structure was systematically studied. The network structure was investigated by the Fourier Transform Infrared (FT-IR), Raman spectra, and Solid State Nuclear Magnetic Resonance (SSNMR). Herein, B2O3 addition can continuously decrease the refractive index and density. When B2O3 is lower than 2 mol%, B2O3 addition can obviously decrease the scalar crystal field parameters, Yb3+ asymmetry degree, Yb3+ cross-sections, due to the generation of Yb–O–B bonds at the cost of partial Yb–O–Al/Si ones. When B2O3 is more than 2 mol%, FT-IR, Raman spectra, and SSNMR results indicate that further increased B atoms prefer to connect with Si and Al rather than Yb. Consequently, the above parameters are basically unchanged. Based on the results, an intuitive model of structure and properties evolution during the substitution of SiO2 by B2O3 has been established. 相似文献
69.
70.
《International Journal of Hydrogen Energy》2020,45(17):10602-10612
Owing to high specific energy and low emissions production, hydrogen is a desirable alternative fuel. The combustion and emission performance can be improved by hydrogen addition injected in-cylinder, intake manifold and aspirated with air. However, engine loads and hydrogen-air ration have a significant effect on the performance, combustion and emission of the diesel-hydrogen (high speed direct injection) HSDI engine. In this paper, the CFD method is used to calculate the combustion process of a diesel-hydrogen dual HSDI engine working at constant speed of 4000 rpm, at different hydrogen added from intake port (hydrogen volume fraction of 0%–10%) and five engine loads (equivalent to 20%, 40%, 60%, 80% and 100% of its maximum output power), respectively. The modelling results showed that the in-cylinder pressure and temperature under low engine load were more affected by hydrogen addition. With increasing hydrogen volume fraction, the indicated expansion work and in-cylinder peak pressure increased, and combustion duration decreased due to faster fuel-air mixing and spray flame speed. 相似文献