Sulfuric Acid Mist: Generation,Suppression, Health Aspects,and Analysis

Sulfuric acid mist, which is generated in electrowinning tankhouses, poses corrosion problems to the tankhouse structure and adverse health effects to employees. The literature pertaining to the generation of acid mist from bursting bubbles as film and jet droplets is reviewed. In addition, various methods of suppressing acid mist, such as the use of surfactants, balls, and hoods, are presented and discussed. The occupational exposure limits in various countries are presented and the commonly accepted methods of sampling acid mist are reviewed. Data on acid mist from a survey of 25 zinc and copper tankhouses are summarized.     

Smart structures and their applications on active vibration control: Studies in the Department of Aerospace Engineering, METU

This work presents the theoretical and experimental studies conducted in Aerospace Engineering Department of Middle East Technical University on smart structures with particular attention given to the structural modelling characteristics and active suppression of in-vacuo vibrations. The smart structures considered in these analyses are finite and flat aluminium cantilever beam-like (called as smart beam) and plate-like (called as smart fin) structures with surface bonded lead–zirconate–titanate patches. Finite element models of smart beam and smart fin are obtained. Then the experimental studies regarding open loop behaviour of the structures are performed by using strain gauges and laser displacement sensor to determine the system models. Further studies are carried out to obtain H _∞ and μ-synthesis controllers which are intended to be used in the suppression of free and forced vibrations of the smart structures. It is observed that satisfactory attenuation levels are achieved and robust performance of the systems in the presence of uncertainties is ensured. In that respect a comparative study involving H _∞ and sliding mode controls is also conducted. Recently, the studies involving aerodynamic loading are also gathering pace.     

Experimental investigation of mixing-enhanced swirl flows

The experimental objective was to compare disintegration characteristics from the internal mixing pneumatic nozzles under the different operating conditions in terms of swirl angles. For this investigation, supplied air pressures and nozzle configuration ratios were fixed. This experimental comparison is of fundamental importance to the understanding and modeling of turbulent atomization because the axisymmetric swirling flows involve relatively complex interactions. For the measurement, four internal swirl mixing nozzles with axisymmetric holes at swirl angles of 15°, 30°, 45°, and 60° to the central axis were employed, which is responsible for the enhancement of mixing in pneumatic jets. To illustrate the swirl phenomena quantitatively, the distributions of mean velocities, turbulence intensities, and SMD (Sauter mean diameter, or D₃₂) variations with different configuration ratio were comparatively analyzed. It indicated that the atomization characteristics are performed well in the case of 30° of swirl angle, and that turbulence intensities are gradually degenerated with the increase of radial distances, showing a slight increment of SMD at downstream region. In particular, measurements showed that nozzle configuration is one of the significant geometrical parameters affecting the spray trajectories. This paper was recommended for publication in revised form by Associate Editor Jun Sang Park     

鹤矿兴安新主井低压动态滤波无功补偿探讨

部分绞车尤其是提人的竖井和斜井绞车,在受到谐波的影响时,会造成人身事故,带来隐形隐患,因而不能保证设备的正常运行和可靠供电,减少谐波对电网的污染,改善供电电网质量,抑制谐波电流的技术措施,补偿基波无功功率,提高功率因数是主要任务。     

二氧化碳发生器在煤矿应急救援工作中的应用与前景

介绍了二氧化碳发生器的结构、工作原理及其性能,叙述了二氧化碳惰气的灭火和抑爆机理,探讨了二氧化碳发生器在煤矿应急救援工作中的应用与前景。     

基于STFT和WT的SAR干扰抑制算法

窄带干扰(NBI)和宽带干扰(WBI)作为合成孔径雷达（SAR）中最为常见的两种干扰形式,它们的存在将会大幅度地降低SAR图像的质量.本文在对NBI和WBI的时频聚集性分析的基础上,提出一种联合短时傅里叶变换和小波变换的NBI和WBI抑制方法.该方法首先把SAR回波数据变换到短时傅里叶谱域再把短时傅里叶谱域数据变换到小...     

Suppression of by-product generation in the treatment of aromatic perfumery substances using a surface discharge

Treatment of perfumery materials such as aromatic hydrocarbons was attempted using atmospheric surface discharge and UV light irradiation. The maximum decomposition rate of phenyl ethyl benzene with a concentration of 8% using the discharge with UV light is 96%, that is 12% higher than that without UV light. Combination of surface discharge and UV light enhances the decomposition rate and energy efficiency, and enables to suppress the generation of by-products such as benzene.     

Weight suppression predicts weight gain over treatment but not treatment completion or outcome in bulimia nervosa.

The authors attempted to replicate previous findings that weight suppression is a significant predictor of treatment completion and treatment outcome (M. L. Butryn, M. R. Lowe, D. L. Safer, & W. S. Agras, 2006) and weight gain over treatment (M. R. Lowe, W. Davis, D. Lucks, R. A. Annunziato, & M. L. Butryn, 2006) among women with bulimic disorders. The authors also examined 2 alternative measures of weight variability. Participants were 132 women with bulimia nervosa treated with cognitive-behavioral therapy. Participants who dropped out of treatment did not have significantly higher levels of weight suppression than did treatment completers. Among those who completed treatment, weight suppression did not significantly predict binge eating and purging at post-treatment. Weight suppression did significantly predict weight change and, in particular, weight gain (≥5 kg) over treatment. Alternative measures of weight variability did not significantly predict treatment completion or treatment outcome, but 1 measure significantly predicted weight gain over treatment. In conclusion, the authors failed to replicate the previous finding that weight suppression predicts treatment compliance and treatment outcome, but they did replicate the finding that weight suppression predicts weight gain over treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种MIMO雷达谱修正旁瓣抑制方法的研究

在窄带频分MIMO雷达系统中,由于接收机带宽受雷达系统的限制,而MIMO雷达发射频分的正交信号,所以子带信号带宽较小,从而导致信号时带积变小,因此信号具有较大的距离旁瓣。针对MIMO雷达信号旁瓣高的问题,提出了一种采用谱修正技术抑制MIMO雷达距离旁瓣的方法。将MIMO雷达回波信号经过波束形成和匹配滤波后的综合输出信号频谱进行谱修正处理,计算机仿真和对实测数据的处理证明,这种方法能有效地抑制MIMO雷达的距离旁瓣。     

基于瞬时无功功率理论的谐波检测和抑制的模型参考自适应控制系统

针对瞬时无功功率理论的低通滤波器的选型问题,通过对提取出的基波电流作快速傅里叶变换(FFT)分析,以各次谐波含量和总谐波畸变率(THD)作为Butterworth低通滤波器的阶数和截止频率选择的依据。首先,建立了谐波源公共连接点(PCC)处基于瞬时无功功率理论的谐波检测的仿真模型;其次,根据提取的基波电流的畸变程度,详细说明了低通滤波器的选型方法;最后,将模型参考自适应理论引入开环谐波检测系统,克服了实际模型中内部参数改变和外部扰动对谐波检测的影响。理论分析和仿真实验表明,该系统具有良好的谐波检测精度和对基波提取具有较强的鲁棒性和自适应性。