电磁振动高频振网筛数字控制系统

电磁振动高频振网筛数字控制系统结合计算机技术、电子技术和网络技术,取代传统筛机的电位器式控制,在提高筛机工作参数控制精度的同时,还大大降低了操作难度,操作者可对所有筛机进行现场控制和集中控制,随意设置和查询系统中筛机的工作参数和历史记录,丰富的人机交互界面,使操作直观、简单。因而被广泛应用于选矿、选煤、制砖等行业,有效地提高了筛分效率,降低了劳动强度,提高了管理水平。其创新点在于实现了现场控制和远程集中控制,使高频振网筛控制水平提高一步,取得了极大的经济效益和社会效益。     

应用于高频数字化LLC谐振变换器的变模态调制策略

以数字化LLC谐振变换器为研究对象,针对其达到1MHz应用时出现的频率分辨率不足及其导致的输出电压脉动问题,提出了一种抑制该问题的变模态调制策略。该策略包含两个模态：传统的仅调节频率的频率调制模态和频率及占空比同时调节的复合调制模态。在复合调制模态下,当检测到开关频率以最小频率间隔来回跳动时,锁定开关频率并通过调节占空比以实现对变换器电压增益的精细调节,从而抑制单一频率调制下出现的输出电压脉动问题。文中给出了该策略的工作原理分析、设计要点分析,并在一台1 MHz的样机上完成了对比实验,实验结果验证了所提出变模态策略的有效性。     

高频纳秒脉冲串作用下皮肤肿瘤热效应的多参数有限元仿真与实验

为综合传统微秒脉冲电场和纳秒脉冲电场治疗肿瘤的优点,提出一种高频纳秒脉冲串的脉冲形式来治疗肿瘤。研究此高频纳秒脉冲串在生物组织中产生的热效应,并通过多参数有限元方法对施加镊子电极的皮肤黑色素肿瘤的温度以及热损伤进行仿真。施加的电场强度范围为1~10k V/cm,脉宽范围为50~500ns,脉冲串内重复频率介于100k Hz和1MHz之间,一串脉冲的长度为100μs,脉冲串重复频率为1Hz。对于皮肤肿瘤,施加电场强度5k V/cm、脉宽500ns、脉冲串内重复频率1MHz的脉冲,1s后肿瘤的最高温度仅为37.4℃,热损伤可以忽略不计。对不同电场强度、脉宽、重复频率下皮肤黑色素肿瘤的温度和热损伤进行仿真计算,研究肿瘤温度以及热损伤与脉冲参数的关系,并确定使肿瘤不发生热损伤的脉冲参数范围。对裸鼠在体黑色素肿瘤的温度进行实测,肿瘤的温升结果与仿真中的平均温度变化较为一致。     

Dry reforming of CO2CH4 assisted by high-frequency AC gliding arc discharge: Electrical characteristics and the effects of different parameters

In this work, a knife-shaped gliding arc discharge (GAD) reactor driven by high frequency AC (HFAC) power was employed to convert CO₂ and CH₄. The HFAC GAD exhibited good performance in dry reformation of CO₂CH₄. The development process with the HFAC GAD at a low gas flow rate was recorded and it is discussed with U-I waveforms and discharge images. The effects of input voltage, total gas flow rate, minimum electrode gap distance, and electrode thickness were investigated in terms of the CO₂CH₄ conversion rate, selectivity of CO, H₂, and C₂ hydrocarbons, specific energy density, and energy efficiency. The energy efficiency ranged from 1.58 to 2.21 mmol/kJ under changing operating conditions. The best conversions of CO₂ and CH₄ were achieved as 52.32% and 58.85%, respectively, with an energy efficiency of 1.65 mmol/kJ.     

EWB软件在《高频电子技术》实验中的应用

本文介绍了EWB仿真软件的特点及其在《高频电子技术》课程教学中的具体应用,将传统的实验方法与EWB的相结合,还可以使学生对新知识产生浓厚的探索兴趣,能有效地提高实验教学质量。     

超频呼叫的实时监控与处理

简要介绍了超频呼叫的主要特征,以及挂表跟踪和话单分析方法 2种超频呼叫监控手段;详细论述了如何利用启用试呼话单、构建计费话单采集网络、话单的实时筛选和分析、启用综合网关的第三方接口及对综合网关的黑名单进行扩容等5个步骤,在华为网管上对超频呼叫实现实时监控与处理,并就如何通过配置录音通知设备提高端局系统接通率问题进行了论述。     

Influence of magnetic annealing on high-frequency magnetic properties of FeCoNd films

FeCoNd thin film with thickness of 166 nm has been fabricated on silicon (1 1 1) substrates by magnetron co-sputtering and annealed for one hour under magnetic field at different temperatures (T_a) from 200 °C to 700 °C. The As-deposited and annealed FeCoNd film samples at T_a ≤ 500 °C were amorphous while the ones obtained at T_a ≥ 600 °C were crystallized. We found that the perpendicular anisotropy field gradually decreases as the annealing temperature increases from room temperature to 300 °C. A well induced in-plane uniaxial anisotropy is achieved at the annealing temperature between 400 and 600 °C. The variation of the dynamic magnetic properties of annealed FeCoNd films can be well explained by the Landau-Lifshitz equation with the variation of the anisotropy field re-distribution and the damping constant upon magnetic annealing. The magnetic annealing might be a powerful post treatment method for high frequency application of magnetic thin films.     

High-frequency welding of glass–fibre-reinforced polypropylene with a thermoplastic adhesive layer: Effects of ceramic type and long-term exposure on lap shear strength

In this study, high-frequency (HF) welding of glass–fibre-reinforced polypropylene (GF/PP) with thermoplastic adhesive layers consisting of zinc oxide (ZnO), anatase-type titanium oxide or silicon carbide was investigated. Effects of the ceramic type and content on the dielectric and temperature characteristics of these adhesive layers were evaluated experimentally, and the ratio of the dielectric loss tangent to the relative dielectric permittivity (tanδ/ε′), which was the index of the HF heating efficiency, exhibited different tendencies by these parameters. This value increased rapidly with increasing temperature even at 10 vol% ZnO, suggesting that the heating of the adhesive layer may be accelerated by combining temperature rise with a small amount of ZnO. During the HF welding process, the ZnO-containing adhesive layer bound to GF/PP in the shortest time (18 s) with high bond strength (~14 MPa). The effects of temperature (50 °C) and moisture (80% relative humidity) on the mechanical strength of the HF-welded specimens after a long-term exposure were also examined.     

工频、冲击接地电阻及高频低阻抗等电位联结

接地的内涵不仅包括需要接地的电气回路导体或电气设备金属外壳与大地的连接,还包括它们与替代大地的某些导体的连接,即等电位联结。对工频而言,接地回路起主导作用的是电阻;对高频而言,起主导作用的则是电抗。     

非晶态合金高频方波逆变电源输出变压器的分析和设计方法研究

对采用非晶态合金材料制作高频方波逆变电源输出变压器的分析和设计方法进行了初步探讨和研究，并利用研究的结论、设计制作了样机，同时还给出了具体的设计实例和测试结果。