焦炉高压氨水泵闭环控制技术的开发应用

采用变频调速技术，利用高压氨水流量信号，组成高压氨水变步 环控制系统，消烟装煤状况电机以４３ＨＺ频率运行，不消烟状态电机以２２ＨＺ频率运行，有效地改善了工艺状况，减轻设备维护量，且节电效果显著。     

高压变频电机控制回路的信号交接

高压变频电机调速系统涉及的电气设备较多,操作不便。为此提出设定高压变频电机的操作原则,同时增加相关电气设备之间的信号交接的方案。实际应用效果显示,该方案可有效保证高压变频电机在运行和操作过程中的安全性和可靠性。     

浅析高压变频器节能技术应用发展

随着变频调速技术的发展,作为大容量传动的高压变频调速技术得到了广泛的应用.高压电机利用高压变频器实现无级调速,从而满足生产工艺对电机调速控制的要求,很大程度节约能源,降低了生产成本.     

白云铁矿东采场2#胶带运输机变频改造

高压电机使用变频控制可以有效的防止电机在启动过程中对周围电网的影响,高压电机利用高压变频器可以实现无级调速,满足生产工艺过程对电机调速控制的要求,以提高产品的产量和质量,又可大幅度节约能源,降低生产成本。但是高压变频器可能对电网及电气设备产生不良影响。因此,关注变频技术在高压电机运用中是否能稳定的工作也显得至关重要。     

中厚板厂高压水除磷泵采用变频调速后的效果分析

对天钢中厚板厂高压水除鳞泵主电机应用变频调速系统后的效果进行了分析。结果证明,采用变频调速系统后,节能效果明显,传动效率提高,设备运行更稳定,有利于延长设备寿命。     

高压变频器在矿井风机中的应用

本文简要介绍了一种6kV无换向器电机直接高压变频调速装置的构成、主要技术问题以及矿井主 扇风机利用其调速节能运行的节能原理和效果。     

变频调速与传统调速方式在我厂提升装置上的应用比较

鉴于传统电机调速方式暴露出来的电气设备易老化、电机机械特性软、能源损耗大等弊端,寻求一种全新的电机调速方式将成为必然趋势。随着变频技术的日益成熟,以及变频调速的带负载能力强、启动力矩大、实现电机软启动、输出恒转矩、可实现电机无级调速、电流冲击小、加减速过程平滑等优点,使变频调速在提升装置上的应用越来越得到认可,变频调速最终将代替传统调速方式来控制提升电机的运行。     

莱钢400m~2烧结机1~#主抽风机高压变频技术改造

莱钢400 m2烧结机1#主抽风机电机采用AMB-HVI高压变频调速系统进行变频调速节能改造,主回路采用一拖一变频器,采用风水冷系统装置,高压变频系统完全独立。技术改造后,降低了设备负载和运转速度,延长电机、风机等备件使用寿命,节省了维护费用,每月可节省电费76.893万元。     

国产高压变频器在除尘风机上的应用

为了进一步节能降耗、降低生产成本,济钢第三炼钢厂LF精炼炉除尘风机采用了国产高压大功率变频调速技术。变频系统采用多个功率单元串联的形式,通过“功率裂变”与高压“再生”技术,直接带动高压电机,输出谐波小;采用“STT”技术,旋转负载可直接启动;采用高压输出突发短路“SCP”防护技术,可有效保护电机和变频系统的安全。改造后运行情况表明,平均节能率达55％,年节约电费208万元。     

炼钢系统一次除尘电机节电空间分析

介绍了马钢第二钢轧总厂目前炼钢系统一次除尘电机的概况及功耗情况。分析了高压变频调速的优点以及一次除尘风机分别在液力偶合器调节和高压变频器调节状况下的电耗,同时进行了投资效益比较。     

电磁搅拌下稀土在铝合金熔体中的分布规律

应用Ansys软件中电磁场模拟模块Ansoft以及流场模块Fluent,研究在单一低频旋转电磁场作用下A356-1.2 %La熔体中稀土La的运动规律以及分布规律. 通过对单一低频且搅拌时间短暂电磁搅拌情况下的A356-1.2 %La熔体进行建模仿真,并着重对电磁搅拌频率分别为f=5 Hz、15 Hz、30 Hz时稀土La的分布情况进行对比分析,最终得出当电磁搅拌频率f=30 Hz时熔体内稀土La分布相对均匀;且一定条件下随着电磁搅拌时间以及频率的增加,稀土La在A356-1.2 %La熔体内的分布也越均匀;并证实通过Ansys软件中电磁场模块Ansoft以及流场模块Fluent可以较好地对旋转电磁场内铝-稀土多相熔体中稀土的运动情况进行数值仿真.      

Masking of tones by noise for the goldfish (Carassius auratus).

Using a classical respiratory conditioning technique, tonal thresholds were measured for 4 goldfish at 5 frequency points between 100 and 1,200 Hz in quiet and under 3 levels of broadband noise. Masking was a linear function of noise level at all frequencies. Signal-to-noise ratios were lowest at 100 Hz (13 db) and increased linearly with log frequency at a rate of 3 db/octave. The values at frequencies above 200 Hz were about 2.5 db above those previously found for the cat and at 1,200 Hz were considerably below those for the rat. Below 200 Hz, however, the values fell below those reported for humans. This sensitivity of the fish in detecting signals in noise provides support for the notion that a mechanical frequency-to-place transformation at the periphery of an auditory system is not a necessary assumption in accounting for some aspects of frequency analysis. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cigarette smoke-inhibition of neurogenic bronchoconstriction in guinea-pigs in vivo: involvement of exogenous and endogenous nitric oxide

1. We investigated the effect of acute inhalation of cigarette smoke on subsequent non-adrenergic, non-cholinergic (NANC) neural bronchoconstriction in anaesthetized guinea-pigs in vivo by use of pulmonary insufflation pressure (PIP) as an index of airway tone. The contribution of endogenous nitric oxide (NO) was investigated with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). The contribution of plasma exudation to the response was investigated with Evans blue dye as a plasma marker. 2. Inhalation of 50 tidal volumes of cigarette smoke or air had no significant effect on baseline PIP. In the presence of propranolol and atropine (1 mg kg(-1) each), electrical stimulation of the vagus nerves in animals given air 30 min previously induced a frequency-dependent increase in PIP above sham stimulated controls (16 fold increase at 2.5 Hz, 24 fold increase at 10 Hz). In contrast, in smoke-exposed animals, the increase in subsequent vagally-induced PIP was markedly less than in the air controls (90% less at 2.5 Hz, 76% less at 10 Hz). 3. L-NAME (10 mg kg[-1]), given 10 min before air or smoke, potentiated subsequent vagally-induced (2.5 Hz) NANC bronchoconstriction by 338% in smoke-exposed animals, but had no significant effect in air-exposed animals. The inactive enantiomer D-NAME (10 mg kg[-1]) had no effect, and the potentiation by L-NAME was partially reversed by the NO-precursor L-arginine (100 mg kg[-1]). Vagal stimulation did not affect the magnitude of vagally-induced bronchoconstriction 30 min later. 4. Cigarette smoke exposure reduced the magnitude of subsequent bronchoconstriction induced by neurokinin A (NKA) by 37% compared with the effect of NKA in air-exposed animals. L-NAME had no significant effect on the smoke-induced inhibition of NKA-induced bronchoconstriction. 5. Vagally-induced plasma exudation in the main bronchi was greater in smoke-exposed animals compared with air-exposed animals (120% greater at 2.5 Hz, 82% greater at 10 Hz). 6. We conclude that cigarette smoke-induced inhibition of subsequent NANC neurogenic bronchoconstriction is not associated with inhibition of airway plasma exudation and is mediated in part via exogenous smoke-derived NO, or another bronchoprotective molecule, and by endogenous NO.     

集成运算放大器消振与调零研究

分析讨论了集成运算放大器的消振与调零问题，针对不同类型的集成运算放大器，提出了消振、调零的方法，并给出了实用电路．     

Lateralization of high frequency, amplitude modulated sounds as a function of carrier frequency

Twenty subjects made graphic ratings of the perceived laterality of amplitude modulated sounds that were presented through earphones. A 200 Hz modulation frequency was combined with carrier frequencies of 2200 Hz, 3200 Hz, 4200 Hz, and 5200 Hz. The modulator sinusoid was delayed to either ear by temporal intervals ranging from zero to 0.6 ms. A significant interaction of carrier frequency with the linear trend for interaural temporal disparity indicated that the slopes of laterality ratings on temporal disparity decreased with carrier frequency. A significant interaction of carrier frequency with the difference in ratings for the 0.6 ms delays to the two ears indicated that the range in laterality ratings decreased with carrier frequency. The results indicate that the amount of laterality is a decreasing function of carrier frequency for high frequency sounds, which may be a consequence of greater weight being given to zero intensity difference as frequency increases.     

The use of Baypamun N in crowding-associated infectious respiratory disease: efficacy of Baypamun N (freeze dried product) in 2-week-old veal calves

BACKGROUND: Disturbances of blue color vision and of temporal contrast sensitivity can indicate early damage in glaucoma. For the present study a quick and easy test was devised which examines both functions at one time by testing the temporal contrast sensitivity of a blue flickering light on an intense yellow background. METHODS: Large coextensive background and test fields (85 degrees) are used, making fixation uncritical. Detailed experiments were made in two normal subjects to derive spectral sensitivity curves from flicker-fusion frequency (FFF) versus intensity functions and to obtain complete temporal contrast-sensitivity (De Lange) curves under different levels of adaptation and test lights. After selection of appropriate luminances and one stimulation frequency from these experiments, test-retest variability was studied in four subjects in five repetitions. In addition, normal values were collected from 22 subjects. RESULTS: Spectral sensitivities for two levels of FFF (15 Hz and 44 Hz) agree with Stiles' pi 1 at the low and with pi 4 at the high FFF. Temporal contrast-sensitivity curves show a low-frequency section with peak sensitivity at 1 Hz and a high-frequency section with a peak at around 4 Hz. From the basic experiments the following conditions for the clinical examination were selected: Background luminance 2600 cd/m2, test luminance at 451 nm 0.8 cd/m2, stimulation frequency 4 Hz. The test-retest variability showed an acceptable intraclass correlation co-efficient (0.6). CONCLUSIONS: The present experiments carried out with a very large stimulus led to meaningful results which are in rather good agreement with results reported in the literature on small-field stimuli. The blue-on-yellow flicker test carried out under the conditions mentioned above is a quick and easy test which could be helpful in improving early glaucoma diagnosis.     

广西大新碳酸锰矿石的干选试验研究

初次探讨用正交设计法来寻找YHXTG-4012型永磁干式强磁选机对广西大新碳酸锰矿石进行磁选试验的最佳工艺条件。试验结果表明：在水分为1%~2%,给矿口40 mm,磁筒电机频率45 Hz,磁筒挡板间隙30 mm,磁辊电机频率50 Hz,磁辊挡板间隙25 mm的最优工艺条件下,经干式磁选,碳酸锰原矿品位从15.93%提高到了22.22%,精矿产率62.33%,回收率86.95%,取得了良好效果。     

浅谈罐式煅烧炉排烟机的变频节能技术

传统罐式煅烧炉排烟机一般采用异步电机驱动,采用插板方式调节烟气流量,在生产中存在电能浪费、调整不便等缺点。排烟机电机变频技术改造是降低电能消耗、方便调整的一个有效方法。本文介绍了某公司罐式煅烧炉排烟机的变频节能技术改造过程、变频原理及项目效果等。     

电解金属锰硫化除重金属的理论分析与生产实践

阐明了电解金属锰硫化除重金属的理论分析，论述了形成硫化物的平均pH值以及某些金属硫化物溶度积与温度(1／T)的关系，提供了生产实践中的硫化净化除杂的主要化学反应和技术条件。     

Effects of motor programming on the power spectral density function of finger and wrist movements.

Power spectral density analysis was applied to the frequency content of the acceleration signal of pen movements in line drawing using 10 right-handed college students. The relative power in frequency bands between 1 and 32 Hz was measured as a function of motoric and anatomic task demands. Results showed a decrease of power at the lower frequencies (1–4 Hz) of the spectrum and an increase in the middle (9–22 Hz) with increasing motor demands. These findings evidence the inhibition of visual control and the disinhibition of physiological tremor under conditions of increased programming demands. Adductive movements displayed less power than abductive movements in the lower end of the spectrum, with a simultaneous increase at the higher frequencies. The relevance of the method for the measurement of neuromotor noise as a possible origin of delays in motor behavior is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)