Simulations of NBI fast ion loss in the presence of toroidal field ripple on EAST

NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO. The ripple effect was included in the upgraded version of the GYCAVA code. It is found that loss regions of NBI fast ions are mainly on the low field side near the edge in the presence of ripple. For co-current NBIs, the synergy effect of ripple and Coulomb collision on fast ion losses is dominant, and fast trapped ions located on the low field side are easily lost. The ripple well loss and the ripple stochastic loss of fast ions have been identified from the heat loads of co-current NBI fast ions. The ripple stochastic loss and the collisioninduced loss are much larger than the ripple well loss. Heat loads of lost fast ions are mainly localized on the right side of the radio frequency wave antennas from the inside view toward the first wall. For counter-current NBIs, the first orbit loss due to the magnetic drift is the dominant loss channel. In addition, fast ion loss fraction with ripple and collision for each NBI linearly increases with the effective charge number, which is related to the pitch angle scattering effect.     

Growth mechanism and gas-sensing characteristics of organic-additive-free zinc oxide of various shapes

Zinc oxide is widely used in gas sensors, solar cells, and photocatalysts because of its wide bandgap and exciton binding energy of 60 meV in various metal oxides. To use ZnO as a gas sensor, it is necessary to synthesize it with surface defects and a large specific surface area. In this study, hydrothermal synthesis without surfactants was employed to obtain organic-additive-free ZnO. For morphology control, we varied the ratio of the hydroxide ion concentration to the zinc ion concentration. To confirm the growth mechanism of ZnO, we performed X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. Raman spectroscopy and photoluminescence measurements were performed to analyze the surface properties. The Brunauer–Emmett–Teller method and probe stations were used to measure the specific surface area and sensitivity of the gas sensor, respectively. The results confirmed that flower-shaped ZnO is the most suitable gas-sensing material.     

基于混合模式快速电荷平衡的神经刺激器

设计实现了一种可用于脊髓神经刺激器的多通道大电流神经刺激器。提出将电极短接和插入短电流脉冲相结合的混合模式,在大电流下,能更加快速地实现电荷平衡。电路设计上,将ADC动态比较器的回踢噪声消除技术应用于神经刺激器,使得动态比较器在输入压差较小时能够输出正确的比较结果,从而将电极上残留电压保持在更安全的范围内。基于CSMC 0.25 μm BCD工艺进行设计与仿真,结果表明,在单向且最大刺激电流为4 mA、刺激脉宽为60 μs、刺激周期为750 μs的条件下,该15 V、16路神经刺激器能实现±50 mV安全电压的有源电荷平衡。     

Analysis of bio-oil physicochemical properties and aging process

The physicochemical properties of bio-oil obtained from pyrolysis of rape straw were studied. Main components of bio-oil were qualitatively analyzed by gas chromatography-mass spectrometry and Fourier-transform infrared spectroscopy. It was found that the main components of bio-oil were alcohols, aldehydes, phenols, esters, ketones, and acids. Two-stage condensation device was adopted to enhance the output of bio-oil to 43.53%. The storage and aging process of bio-oil was observed. Viscosity-temperature curve of aging bio-oil was fitted by Matlab programming. Change regulation of chemical compounds and functional groups before and after aging process were analyzed.     

一种基于全变分技术和Lp伪范数的椒盐噪声去除方法

针对传统各向同性全变分（Isotropy total variation，ITV）去噪算法容易导致图像边缘模糊、不易保持图像细节信息等问题，提出一种基于L _p 伪范数和各向同性全变分的图像去噪方法。该方法将L _p 伪范数代替ITV模型中的L ₁范数，利用交替方向乘子算法（Alternating direction method of multipliers, ADMM）将能量泛函拆解成若干个子问题，并将差分算子视为卷积算子；然后引入卷积定理和快速傅里叶变换(Fast Fourier transform, FFT)提高算法运算效率；最后通过Matlab进行仿真实验，运用图像质量的客观和主观评价方法进行评价分析。结果表明，本文方法能够较好地保留图像的边缘特性，有效提升去噪效果。     

基于改进奇异值分解滤波和谱峭度的滚动轴承故障诊断

针对含噪信号的有效奇异值个数难以确定的问题，提出了一种改进的奇异值分解降噪方法--奇异值累积法。该方法通过计算奇异值的实际下降值与奇异值平均下降速度累积量的差值，并取该差值最大值点的位置作为有效奇异值的分界点来确定有效奇异值的个数。在此基础上，提出了一种基于奇异值累积法与快速谱峭度的滚动轴承故障诊断方法。采用奇异值累积法对原信号进行降噪处理，然后利用快速谱峭度确定滤波器中心频率及带宽，通过分析频段包络谱中明显的频率成分来诊断故障。该方法可以有效去除信号中的噪声，使得到的峭度值所反映的故障冲击更接近实际情况。对含内圈、外圈故障的滚动轴承实验数据进行分析，实验结果表明，相比快速谱峭度的故障诊断方法，该方法具有更好的故障识别效果。     

高温高盐油藏化学驱数值模拟技术进展

针对高温高盐油藏，胜利油田近年来先后研发了非均相体系、乳液表面活性剂体系等新型驱油体系，其驱油机理与传统化学驱油体系有明显的区别，现有商业化数值模拟软件无法有效表征，而自研数值模拟软件存在运算速度慢、难以支撑大规模矿场应用等难题。依托自主知识产权的化学驱数值模拟软件SLCHEM，在室内实验与机理研究基础上，建立了基于粘弹性颗粒孔喉通过系数的非均相复合驱数学模型以及表征乳液表面活性剂乳化增粘特征的数学模型，实现了相应的模拟功能，开展了室内试验的拟合与矿场模型应用，验证了模型的合理性和准确性；综合应用顺序全隐式快速求解算法、并行解法及交替方向解法，实现了百万级规模模型的快速计算。通过概念模型进行了计算效率测试，在网格数100×10⁴、井数116口、生产历史5a条件下，计算速度为2.9h。室内实验验证与矿场实际应用表明，与商业化软件相比，改造后的SLCHEM软件能够实现对新型驱油体系室内实验结果与矿场动态指标的准确拟合，可为化学驱方案优化与动态分析提供有效的技术支持。     

浅谈液压夹具在转向油缸铸造缸盖加工上的应用

随着液压夹具在机械加工中运用推广,该公司引用液压夹具多年来取得一定成效,文章针对转向油缸的铸造缸盖铣、钻序前后加工工装进行对比分析,重点突出应用全自动液压夹具后可提升装夹效率、加工质量以及降低劳动强度等,可以在不添置设备的情况下,满足产能提升的需求。     

转向系参数对汽车拖车组合系统稳定性的影响

车身摆振是汽车拖车组合系统中一种复杂的动力学失稳现象，它常常表现为车身折叠、侧滑、侧倾等行为，给道路交通安全带来了巨大的隐患。针对此问题，应用拉格朗日方程建立了考虑牵引车转向系统的汽车拖车组合系统6自由度非线性综合模型，并通过非线性分析方法研究了转向系惯性参数和各个结构刚度、阻尼对汽车拖车组合系统稳定性的影响。结果表明，转向系结构参数对系统稳定性存在不同影响，合理选择转向系结构参数可以有效提高汽车拖车组合系统的动态稳定性。     

Bio-oil production by fast pyrolysis of cassava residues in a free-fall reactor using liquid media-assisted condensation

We investigated the influence of liquid media-assisted condensation on the bio-oil yield using biomass derived from cassava rhizomes and stalks in a free-fall reactor. Benzene, diesel, engine lubricant, and ethanol were tested as the liquid medium. Exposure times varied from 60 to 120 min with biomass feed rates from 100 to 250 g/h. Engine lubricant and ethanol tended to decrease biomass yield while increasing gas yield. Benzene and diesel showed slightly increased biomass yield. With benzene, the bio-oil water content (28%) was insignificantly different from that without using any condensation substance. However, with diesel, the water content increased very slightly; with engine lubricant, it decreased to 25%; and with ethanol, it significantly decreased to 12%. Also, using diesel generated higher heating values (30 MJ/kg).