三角波脉冲低压阻垢技术的试验研究

很多工业部门都使用热交换系统,系统内的结垢非常普遍。对三角波脉冲的阻垢防垢效果进行了研究,试验证明三角波脉冲可有效防止热交换系统内的结垢现象,在阻垢率都为100%的情况下,其功率分别只有方波和直流电的1／13和1／40。在三角波脉冲条件下,有效电压越高,阻垢效果越明显。三角波脉冲阻垢技术是水质稳定技术的一个重要的发展方向。     

高频三角波电磁场防治水系统中微生物污垢的研究

工业水系统中微生物污垢广泛存在，实验采用高频三角波对模拟工业水系统中的微生物污垢的防治进行了研究。主要考察了不同流速的流体在未处理和经过不同频率高频三角波处理后，不同材料表面上微生物污垢的生长量的差别以及微生物污垢的生长厚度和形态方面的差异。结果表明：一定流速下5000Hz高频三角波电磁场对实验中使用的非金属材料有明显抑制其表面微生物污垢生长的作用，但是对实验中的金属材料没有抑制作用；高频三角波的抑制作用在距离加载位置较近的实验段比在距离较远的实验段的作用突出，随着与加载位置距离的增大，抑制作用逐渐减弱。     

过程设备的高低周复合疲劳研究

针对在役过程设备受高低周循环载荷的复合作用工况,以25Cr2MoV钢为试件,进行了加载波形分别为三角波、梯形波以及梯形波叠加三角波的疲劳试验,考察了高频交变载荷、波形与保持时间对试件疲劳寿命的影响情况;指出了增加最高应变时的保持时间,会降低材料的疲劳寿命;当高低循环复合疲劳中的高频交变应变幅较大时(如εH=20%εa时),必须考虑高频交变载荷的作用,否则会得到偏于不安全的结果。     

方波脉冲低压阻垢技术的试验研究

电子水处理器是一类新型的水处理设备,可防止热交换系统的结垢。文中对采用方波脉冲电流的电子水处理器的阻垢效果进行了研究。结果表明,当采用平均电压为2V的方波脉冲电流时,对水样阻垢率达到100%,且能一定程度地降低水样的总碱度和总硬度。与三角波脉冲电场相比,在阻垢率均为100%的情况下,方波电场的总碱度和总硬度降低率远高于三角波,有较好的防垢效果。     

不同电场波形下液滴极化变形规律研究

为了深入研究电场波形对液滴变形的影响,基于相场方法,建立了互不相融两流体中液滴变形的仿真模型,实现了流场和电场的耦合。模拟研究了直流脉冲、半正弦波、半三角波和半锯齿波4种电场波形对液滴变形的影响。模拟结果显示,液滴变形度曲线与电场波形相似,且液滴振荡变形的频率与电场频率相同。此外,还研究了以上4种波形电场的场强幅值和频率对液滴变形度的影响。结果显示,电场的均方根RMS越高,液滴变形度越大;随着场强幅值的增加,4种波形条件下液滴变形度近似呈指数增加;随着频率的增加,直流脉冲和半正弦波电场条件下液滴变形度呈先增加后减小的趋势,存在最佳频率40 Hz,半三角波和半锯齿波电场条件下液滴变形度近似呈线性减小。     

Zn—Br电池中DSA表面积的电化学法测定

本文采用三角波电位扫描法对 DSA 在 Zn—Br 电池系统中的工作表面积进行了测定,得出了其实际表面积为几何表面积42倍的结论。该方法有效、可靠,亦可用于其它电极及电解液系统中的测量。     

基于LabVIEW新型虚拟函数信号发生器的开发

介绍一种自行开发的基于LabVIEW虚拟函数信号发生器。与传统函数信号发生器相比,该仪器不但界面友好,而且功能强大、操作简便。它不但可以产生正弦波、三角波、方波、锯齿波,而且还可以产生白噪声及多频波。输出波形频率范围更宽,具有相关参数的调整与同步显示及其幅度频谱分析功能。实现对输出信号的高速离散采样数据的本地存储,以便本地调用和远程传输。     

基于STM32的新型信号发生器设计

给出信号发生器的硬件组成,阐述DDS芯片AD9833的工作原理,SPI通信过程,正弦波、三角波、方波3种信号的软件实现方法。搭建控制平台验证信号发生器的性能,结果表明:该信号发生器信号输出高频噪声少、频率精度高。     

国内外消息

双星机械全自动三角胶单鼓贴合机研制成功中图分类号:TQ330.4 6文献标识码:D青岛双星机械总公司研制成功LGJ1220型全自动三角胶单鼓贴合机。该设备采用电加热方式,能很好地保证贴合三角胶的平整性,贴合盘部位装有不同形状的压辊,分别压合三角胶的不同部位,以确保三角胶与钢丝圈     

数字图像颜色恒常性算法及应用

建立了BP神经网络颜色恒常性算法,对水质氯离子溶液颜色值进行了校正,以提高图像测量精度.实验结果表明：BP神经网络颜色恒常性算法实现了普通光源到标准光源的非线性映射,可以减小或消除电源及光源等因素对测量结果的影响,校正了颜色,提高了测量精度和灵敏度.     

Coloration of stainless steel at room temperature by triangular current scan method

Interference films with gold, red, blue or green color have been successfully produced on stainless steel at room temperature by applying the triangular current scan method. The anodic current scan over the transpassive region led to the forced dissolution of the steel, and the cathodic current on the reverse scan attributed to the reduction of chromate (VI) to Cr³⁺. The metal ions generated by both reactions were hydrolyzed to form an interference film. The thickness (coloration) of the interference film depended linearly on the electrolysis time and the logarithm of the space between the two triangular waves.     

Improvement of electrical and optical properties of ingan/ganbased lightemitting diodes with triangular quantum well structure

Substantial improvement of electrical and optical properties of InGaN/GaN multiple quantum wells (MQWs) was obtained with a triangular band structure. Transmission electron microscopy (TEM) images from the–50 nm. The light-emitting diodes (LEDs) with the triangular QWs showed a lower operation voltage, a higher light output power, and higher intensities and narrower line widths of electroluminescence spectra than those with the rectangular QWs. Very bright and uniform light emission from the triangular MQW LEDs was also observed at a low injection current, but spatially non-uniform emission from the rectangular ones.     

Study of Temperature and Moisture Distribution in Paddy in a Triangular Spouted Bed Dryer

A triangular spouted-bed dryer has been designed as part of a hexagonal continuous dryer for paddy. In the triangular-bed dryer, the spout of drying air is placed in one corner of the drying chamber. Combining six triangular units with the spout located in the center of the dryer allows a continuous process and reduces energy consumption due to the reduction of heat losses. The current study focuses on the distribution of moisture and temperature in an individual triangular bed. Models of distribution have been developed in order to provide a better understanding of the phenomena and to help in scaling-up of the design.     

An evaluation of some tristimulus weights

Tristimulus values were calculated for the 1964 observer and illuminant D65 for four theoretical specimens, with radiance factor data of 1-nm bandpass width, by the CIE recommended procedure and used as accurate references. Tristimulus values were then calculated for the same four theoretical specimens with six sets of published weights, with radiance factors assumed to have a bandwidth equal to the measurement interval and the bandpass profile to be triangular. The difference of the wide bandwidth calculated tristimulus values from the reference tristimulus values was considered to be an error and was expressed as CIE L*a*b* color difference.     

Electroosmotic Dewatering of Tomato Paste Suspension Under AC Electric Field

Laboratory tests have demonstrated electroosmosis under an alternate current (AC) to be effective for dewatering tomato paste suspension. Application of an alternate current (AC) field provided more promising results than those of direct current (DC) electrical field. The results show that the electroosmotic dewatering is influenced by the wave form (sine, rectangular, triangular). The decrease in the wave frequency resulted in an increase in the dewatering rate, whereas increasing the initial bed height increased the dewatering rate.     

MASS TRANSFER IN AC ELECTROLYSIS: EXTENSION OF A FILM MODEL TO TURBULENT FLOW ON A ROTATING HEMISPHERE

Turbulent mass transfer to a rotating hemisphere during AC electrolysis was examined with a film model. The analytical results for the limiting AC current density were compared to the experimental data obtained with sinusoidal, square and triangular wave AC. The limiting AC current density in turbulent flow was found to depend on both the Reynolds number as a dimensionless AC frequency K = (ω/Ω)Sc^1/3. The prediction by the film model agreed with the experimental data to within ±15%. For a given root-mean-square of applied AC, the periodic concentration overpotential decreased in the order of quare, sinusoidal, and triangular AC. The phase shift between the applied AC and the concentration overpotential wave decreased with increasing Reynolds number in turbulent flow.     

MASS TRANSFER IN AC ELECTROLYSIS: EXTENSION OF A FILM MODEL TO TURBULENT FLOW ON A ROTATING HEMISPHERE

Turbulent mass transfer to a rotating hemisphere during AC electrolysis was examined with a film model. The analytical results for the limiting AC current density were compared to the experimental data obtained with sinusoidal, square and triangular wave AC. The limiting AC current density in turbulent flow was found to depend on both the Reynolds number as a dimensionless AC frequency K = (ω/Ω)Sc^1/3 The prediction by the film model agreed with the experimental data to within ±15%. For a given root-mean-square of applied AC, the periodic concentration overpotential decreased in the order of quare, sinusoidal, and triangular AC. The phase shift between the applied AC and the concentration overpotential wave decreased with increasing Reynolds number in turbulent flow.     

MASS TRANSFER IN AC ELECTROLYSIS: EXTENSION OF A FILM MODEL TO TURBULENT FLOW ON A ROTATING HEMISPHERE

Turbulent mass transfer to a rotating hemisphere during AC electrolysis was examined with a film model. The analytical results for the limiting AC current density were compared to the experimental data obtained with sinusoidal, square and triangular wave AC. The limiting AC current density in turbulent flow was found to depend on both the Reynolds number as a dimensionless AC frequency K = (ω/Ω)Sc^1/3. The prediction by the film model agreed with the experimental data to within ±15%. For a given root-mean-square of applied AC, the periodic concentration overpotential decreased in the order of quare, sinusoidal, and triangular AC. The phase shift between the applied AC and the concentration overpotential wave decreased with increasing Reynolds number in turbulent flow.     

MASS TRANSFER IN AC ELECTROLYSIS: EXTENSION OF A FILM MODEL TO TURBULENT FLOW ON A ROTATING HEMISPHERE

Turbulent mass transfer to a rotating hemisphere during AC electrolysis was examined with a film model. The analytical results for the limiting AC current density were compared to the experimental data obtained with sinusoidal, square and triangular wave AC. The limiting AC current density in turbulent flow was found to depend on both the Reynolds number as a dimensionless AC frequency K = (ω/Ω)Sc^1/3 The prediction by the film model agreed with the experimental data to within ±15%. For a given root-mean-square of applied AC, the periodic concentration overpotential decreased in the order of quare, sinusoidal, and triangular AC. The phase shift between the applied AC and the concentration overpotential wave decreased with increasing Reynolds number in turbulent flow.     

The relationship between the impedance of corroding electrode and its polarization resistance determined by a linear voltage sweep technique

The polarization resistance of metallic materials in contact with an electrolyte is largely used for the evaluation of its corrosion rate. The experimental value of polarization resistance is very often determined by plotting the polarization curves at the vicinity of the rest potential by a triangular voltage sweep technique. It is found that, for materials having high resistivity against corrosion, the value of polarization resistance is largely dependent on the sweep rate or the period of sweep cycle. If an equivalent circuit of a corroding electrode is to be presented by a parallel connexion of a resistance and a capacitance, such dependence of the polarization resistance cannot be explained at all. In fact, though the impedance of corroding electrode measured within a large frequency range shows one capacitive arc in the complex plane in accordance with parallel R—C circuit, the values of R and C both depend on frequency. The current response to a triangular voltage sweep signal is calculated numerically by Heaviside operational calculus using experimentally determined electrode impedance. A fairly good agreement was found between the experimental and calculated current—voltage cycles for different periods of a triangular voltage sweep signal.