基于DSP离散小波变换的信号不连续性检测技术

本文介绍了离散小波变换的原理及其在处理非平稳信号时的优势.通过使用离散小波变换对输入的带有间断点的信号进行分析,给出了经过小波变换的结果的图形并进行了分析.本实验硬件平台使用TMS320C5509APGE开发板.     

限流线式自动开关的试验研究

限流线式自动开关的试验研究沈阳电气传动研究所刘文正前言近年来，大型联合企业及石油化工企业规模大、生产流程长，供电系统容量日趋增大，低压配电网路的短路电流也愈来愈大。即要求供电安全、可靠、连续；又要求系统保护电器具有较高的分断能力。为了实现这一目标，近...     

低水泥掺量泵送商品混凝土的性能研究

当今混凝土主要是以水泥为主要胶凝材料的复合材料。它是目前世界上建筑工程中使用量最大、使用范围最广的工程材料。由于混凝土中价格最昂贵的是水泥,所以我们要在确保强度等一系列性能保持良好的情况下,适当通过激发剂的激发效果降低水泥的用量,进而降低成本。并且考虑到混凝土的在泵送的过程中要考虑到可泵性,流动性等性能,外加剂的使用和选择也不容忽视。     

具有内外分段阳极结构的金属离子等离子体推进器的放电特性

金属离子等离子体推进器是一种通过烧蚀阴极金属材料,产生电离度高的金属离子等离子体,在Hump峰加速作用下从而定向喷射形成推力的推进器类型。文中提出了一种带有分段阳极结构的金属离子等离子体推进器(SA-MIPT),该结构由圆锥状阴极、圆筒状绝缘套桶以及圆环状分段阳极组成。基于该金属离子等离子体推进器,探究了峰值电压维持时间t₁以及阳极吸收电子对金属等离子体的生成及喷射性能的影响。研究结果表明,当t₁从0.4μs增大到1.2μs时,单脉冲放电中生成的等离子体的定向传播速度、离子电流幅值以及离子电流与阴极电流的比值G_r分别提高了1.7倍、18倍、15倍。此外,研究发现采用减小阳极裸露面积或者阳极侧串联电阻的方法,能够有效提高从推进器喷口喷射出去的等离子体射流的喷射性能。当内阳极宽度W从2 mm减小到0.1 mm时,放电生成的离子电流峰值以及对应的G_r值分别提高了2.41倍、2.66倍。当阳极宽度W=2mm不变,在内阳极侧串联1 MΩ电阻后,放电生成的离子电流峰值以及对应的G_r值分别提...     

Characteristics and application of diffuse discharge of water electrode in air

Plasma water treatment technology, which aims to produce strong oxidizing reactive particles that act on the gas–liquid interface by way of discharging, is used to treat the organic pollutants that do not degrade easily in water. This paper presents a diffuse-discharge plasma water treatment method, which is realized by constructing a conical air gap through an uneven medium layer. The proposed method uses water as one electrode, and a dielectric barrier discharge electrode is constructed by using an uneven dielectric. The electric field distribution in the discharge space will be uneven, wherein the long gap electric field will have a smaller intensity, while the short one will have a larger intensity. A diffuse glow discharge is formed in the cavity. With this type of plasma water treatment equipment, a methyl orange solution with a concentration of 10 mg l^-1 was treated, and the removal rate was found to reach 88.96%.     

Study on the plasma generation characteristics of an induction-triggered coaxial pulsed plasma thruster

At present,spark plugs are used to trigger discharge in pulsed plasma thrusters (PPT),which are known to be life-limiting components due to plasma corrosion and carbon deposition.A strong electric field could be formed in a cathode triple junction (CTJ) to achieve a trigger function under vacuum conditions.We propose an induction-triggered electrode structure on the basis of the CTJ trigger principle.The induction-triggered electrode structure could increase the electric field strength of the CTJ without changing the voltage between electrodes,contributing to a reduction in the electrode breakdown voltage.Additionally,it can maintain the plasma generation effect when the breakdown voltage is reduced in the discharge experiments.The induction-triggered electrode structure could ensure an effective trigger when the ablation distance of Teflon increases,and the magnetic field produced by the discharge current could further improve the plasma density and propagation velocity.The induction-triggered coaxial PPT we propose has a simplified trigger structure,and it is an effective attempt to optimize the micro-satellite thruster.     

Impact of the Insulator on the Electric Field and Generation Characteristics of Vacuum Arc Metal Plasmas

The field electron emission plays a vital role in the process of vacuum discharge breakdown. The electric field strength at the cathode tip is significant to the generation char- acteristics of vacuum arc metal plasmas. To increase the field strength at the cathode tip, a coaxial electrode plasma source was employed with an insulator settled between the electrodes. The math expression of the field strength is derived based on the Gauss theory. The impact of the insulator on the electric field and parameters of plasmas were investigated by MAXWELL 3D simulation software and the Langmuir probe. In addition, a composite insulator was adopted to further strengthen the field strength. A series of experiments were performed to focus on the role of the composite insulator in detail. The experimental and simulation results indicate that, a reasonable layout of the insulator, especially the composite insulator, can effectively increase the field strength at the cathode tip and the plasma density.     

“调节阀选用技术”讲座 第五讲 调节阀材质的选择

调节阀是自动调节系统中的最终控制元件,它与介质直接接触用来控制各种流体,使用条件恶劣,从清洁干燥的空气到具有很强腐蚀性的石油、化工的介质,其使用温度范围从接近绝对零度到800℃以上,其压力范围从接近真空的低压到3500Kgf/cm~2以上的超高压。因此调节阀材质的选择是调节阀选择中极其重要的问题之一,必须根据不同的使用条件选择最合适的材质,否则,如果材质选择得不合适,将造成产品使用寿命的缩短或根本无法使用。一、对调节阀材质的选择在第一讲中,我们已讲到调节阀由执行机构和阀体组件两部分组成。执行机构部分是调节阀的动力操作装置,不与介质接触,所以对材质的要求只是从强     

大气压辉光放电向弧光放电的转化特性研究

实现稳定的大气压空气辉光放电一直是一个难题,放电极易转换成电弧,且转换时间非常短。基于针-针,针-板两种电极结构,利用MAXWELL 2D仿真软件,分析电极间的电场分布;计算了氮气、氧气所需要的击穿场强,采用脉冲电源驱动,测量放电过程的转换时间。研究显示:两种电极的电场分布和场强最大值不同;放电转化时间为几十纳秒。相同外界条件下的针-板电极比针-针电极具有更大的场强最大值,空间平均场强也比针-针电极大;1 mm间距下的针-针电极击穿时间为25 ns,针-板电极为20 ns。为研究大气压脉冲放电,以及研制纳秒级脉冲功率电源提供了一个时间参数。     

石油炼化装置中泄漏检测与修复技术运用探析

石油化工企业是环境污染大户,石油炼化装置一旦发生泄漏,挥发性有机物就会进入大气中,会破坏臭氧,更能生成二次有机溶胶,导致雾霾。目前研究表明,大气中存在的挥发性有机物,25%源自石油化工企业的储油罐呼吸、炼化装置泄漏。因此遵守国家法律,对石油炼化装置进行泄漏检测,并及时进行修复,是非常积极的环保行为,对其进行探讨具有意义。