基于解析数值法的配电房母排磁场屏蔽

鉴于室内配电房广泛使用的平板形大电流母排,根据母排实际尺寸、位置参数等构建了其工频磁场分布的计算模型,将解析法与数值分析相结合求得空间各点的磁感应强度,以便于磁场屏蔽效能的研究。考虑了配电房母排普遍采用的两种排列方式,着重讨论第一种排列方式对应三种屏蔽方案的屏蔽效果,经计算得出第三种方案的屏蔽效果较为理想。接着研究第三种方案对应屏蔽材料、屏蔽板和母排间距离、屏蔽板厚度和高度等对屏蔽效能的影响。结果显示通过增大材料的磁导率、增加屏蔽板厚度和高度、减小屏蔽板与母排间距离,屏蔽效能呈明显增大趋势。最后针对上述特征给出了提高屏蔽效能的可行建议,以降低配电房周围的磁污染,从而减小对电子设备的干扰和人体健康的影响。

轴承退磁机退磁效果分析

分析了轴承生产过程中磁污染产生的条件及防范措施,介绍了退磁原理、测量与消除残磁的方法、各种退磁机的优缺点及适用范围,并对退磁机存在的问题提出了改进措施,对提高轴承质量有一定的帮助。

高校计算机机房辐射问题的分析和解决思路

随着信息化技术和网络技术的发展,计算机已经逐步普及到千家万户,但是随着计算机数量的增加,电磁辐射对人体造成的伤害也逐渐被人们所重视。本文就从电磁辐射的定义、电磁辐射的危害以及防护措施等几个方面深入分析。得出了电磁辐射的几种常用的防范措施,有效的减少在使用电脑的过程中对身体造成的伤害。

Magnetic Properties of Tree Leaves and Their Significance in Atmospheric Particle Pollution in Linfen City,China

Fifty-one tree leaves were sampled in the industrial area,residential area,and Fenhe River ecological zone,for the purpose of a magnetic study on atmospheric pollution in Linfen City,Shanxi Province,China.Measurements of mass-specific magnetic susceptibility(χ) show a significant variation range(from 11.6 × 10-8 m3/kg to 129.7 × 10-8 m3/kg).Overall values of magnetic susceptibility decline in the following sequence:industrial area > residential area > Fenhe River ecological zone.The relatively elevated concentration-related magnetic parameters(saturation isothermal remanent magnetization,anhysteretic remanent magnetization and magnetic susceptibility) appear in the industrial area,with their highest values in the vicinity of Linfen Steel Mill.Magnetic particles are dominated by multidomain,magnetite-like minerals.Magnetic particle concentration and grain size both decrease with the increasing distance from industrial area,indicating the industrial area,especially Linfen Steel Mill,is the main source of atmospheric particle pollution.Residential area and Fenhe River ecological zone are also affected by industrial emission to a certain extent.The results of this study indicate that magnetic measurements of tree leaves are practicable for monitoring and determination of atmospheric pollution in Linfen City.

Electromagnetic Pollution and Human Health

The electromagnetic fields surrounding the electric and communication installations are blamed not only for cancerigenic effects, but also for negative influences on the natural electrophysiological phenomena and ＂accused＂ of causing some degenerative diseases of the nervous system, genetic modifications with hereditary effects, mental and behavioural disturbances. This research aimed to highlight that Directive 2008 / 46 / EC had a series of positive aspects as well as drawbacks. Directive 2008 / 46 / EC of the European Parliament and of the Council amending Directive 2004 / 40 / EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents （electromagnetic fields） is criticized because these norms should regard not only the category of those working in different domains, but also the large category of consumers （of cell phones, microwave ovens, computers, etc.）.

Magnetic properties and heavy metal contents of automobile emission particulates

Measurements of the magnetic properties and total contents of Cu, Cd, Pb and Fe in 30 automobile emission particulate samples indicated the presence of magnetic particles in them. The values of frequency dependent susceptibility （Xfd） showed the absence of superparamagnetic （SP） grains in the samples. The IRM20mT （isothermal remanent magnetization at 20 mT） being linearly proportional to SIRM （saturation isothermal remanent magnetization） （R^2=0.901）, suggested that ferrimagnetic minerals were responsible for the magnetic properties of automobile emission particulates. The average contents of Cu, Cd, Pb and Fe in automobile emission particulates were 95.83, 22.14, 30.58 and 34727.31 mg/kg, respectively. Significant positive correlations exist between the magnetic parameters and the contents ofPb, Cu and Fe. The magnetic parameters of automobile emission particulates reflecting concentration of magnetic particles increased linearly with increase of Pb and Cu content, showed that the magnetic measurement could be used as a preliminary index for detection of Pb and Cu pollution.

Magnetic field assisted electrocatalytic oxidation of organic pollutants in electroplating wastewater

To degrade the organic compounds in the electroplating wastewater,magnetic field was tentatively introduced into electrocatalytic oxidation on Ti-PbO2 anode.The magnetic field assisted electrocatalytic oxidation can promote anion movement and the generation of active species,resulting more organic compounds to be oxidized and degraded.Oxidation parameters such as treatment time,current density and initial pH of the wastewater were systematically discussed and optimized.The mineralization of organic compounds is improved by over 15% under a magnetic density of 22 mT while the current density is 50 A/m2,pH is 1.8 and the reaction time is 1.5 h.The results indicate that the magnetic field assisted electrocatalytic oxidation has considerable potential in electroplating wastewater treatment.

17α-Ethinylestradiol removal from water by magnetic ion exchange resin

Magnetic ion exchange(MIEX) resins have received considerable attention in drinking water treatment due to their fast and efficient removal of dissolved organic carbon(DOC). Two types of mechanisms, i.e., ion exchange,reversible and irreversible adsorption, may occur during pollutants removal by MIEX. This work examined the removal mechanism of 17α-Ethinylestradiol(EE2) by MIEX. As one of typical estrogen micro-pollutants,EE2 existed as neutral molecule in natural water, and its charge density was close to zero [(0.00000219 ±0.00000015) meq·(μg EE2)^(-1)] based on the potentiometric titration method. However, the removal of EE2 by MIEX was much higher than that of other micro-pollutants previously reported. Multi-cycle adsorptionregeneration experiments and ion exchange stoichiometry analysis were conducted to elucidate the removal mechanism of EE2 by MIEX resin. The results suggested that the main removal mechanism of EE2 by MIEX was ion exchange instead of reversible micro-pore adsorption. The experimental analysis based on Donnan theory indicated that the internal micro-environment of resin beads was alkaline, in the alkaline environment EE2 would be ionized into negatively charged groups. As a result, ion exchange reaction occurred inside the pore of MIEX resin, and the removal process of EE2 by MIEX was dominated by the ion exchange reaction.

Spatial Distribution of Magnetic Properties and Selected Heavy Metals in Calcareous Soils as Affected by Land Use in the Isfahan Region,Central Iran

Anthropogenic activities have caused the accumulation of heavy metals in the soil environment. Pollution of the soils significantly reduces environmental quality and affects human health. In many recent studies, magnetic susceptibility ts have been used for pollution monitoring. The objective of this research was to determine the spatial variability of magnetic properties and selected heavy metals and the effect of land use on their variability in the surface soils of the Isfahan region, Central Iran. A total of 158 composite surface （0-5 cm） samples of calcareous soils were collected from an area of about 700 km2, located along a cross-border transect from Isfahan City to a steel plant, covering urban, industrial, agricultural, and uncultivated land uses. Concentrations of copper （Cu）, zinc （Zn）, lead （Pb）, manganese （Mn）, iron （Fe）, nickel （Ni）, chromium （Cr）, and cobalt （Co） and magnetic parameters, magnetic susceptibility at low frequency （xlf）, natural remanent magnetization （NRM）, saturation isothermal remanent magnetization （SIRM）, and isothermal remanent magnetization at the field of 100 mT （IRM100mT） and the backfield of 100 mT （IRM-100mT）, were measured in all the soil samples. Results showed that magnetic susceptibility in the urban and industrial land topsoils （0-5 cm） samples was significantly higher than that in the agricultural and uncultivated land soils in the study area. Concentrations of Cu, Zn, Pb, Mn, and Fe were positively correlated with magnetic properties （xlf, IRM100mT, SIRM, IRM-100mT, and NRM）, which could be attributed to their inputs from traffic emissions and industrial activities at the study sites. Ni and Cr concentrations showed significant negative correlations with magnetic properties. No significant correlation was found between Co concentration and magnetic parameters. The Tomlinson pollution load index （PLI） showed significant correlation with the magnetic properties （xlf, IRM100mT, SIRM, IRM-100mT, and NRM）. The spatial distribution of the selected heavy metals and xlf in the study area suggested that activities at the urban and industrial land sites caused greater pollution as compared to that at the study sites of other land uses. The concentrations of Cu and Zn seemed to have been affected by anthropogenic sources, whereas Ni, Cr, and Co were mainly controlled by natural sources in the study area. Moreover, the concentrations of soil Pb and Fe in the study area could be affected by both lithologic and anthropogenic sources. The magnetic parameters appeared to be a proxy measure for the degree of heavy metal contamination and could be a potential method for the detection and mapping of contaminated soils.