Combined performance of electrocoagulation and magnetic separation processes for treatment of dye wastewater

In this study, a combined system of electrocoagulation (EC) and magnetic separation (MS) has been applied to the treatment of dye wastewater, and its performance has been evaluated. The floes formed in the electrocoagulation using Fe anode are magnetized and thus they could be removed by magnetic separation. The removal of suspended solids, color and COD was improved with an increase in electric current up to about 15 A and with a decrease in liquid velocities in EC. While the remaining suspended solids in the treated water were reduced to a few ppm and the color was removed almost perfectly (Max. 96%), that of COD was relatively low and only 81%. A further powerful operation can be expected from the present system if it is combined with an additional process, such as electrolysis or oxidation, to reduce COD more efficiently.     

铁磁材料低温磁性能测量研究

采用模拟冲击法研究了铁磁材料在300和77 K环境下的磁性能。以电工领域常用的铁磁材料DT4、1J22、2Cr13和非晶FeSiB为研究对象。结果表明,在液氮环境下,DT4、1J22、2Cr13和非晶FeSiB的饱和磁感应强度均略有增加,其中非晶FeSiB的饱和磁感应强度增幅最大为5.3%; DT4、非晶FeSiB和2Cr13的矫顽力增幅较大,DT4的矫顽力增幅为106%,而1J22的矫顽力减小了1.7%;频率为50 Hz时,在液氮环境下DT4的损耗相比室温急剧增加,增幅达263.2%,非晶FeSiB和2Cr13的损耗相比室温略有增加,而1J22的损耗相比室温变化不大。最后,以超导线圈激磁的强磁场磁控溅射阴极的磁场计算为例,在铁芯结构相同的情况下,采用1J22作铁芯的磁控阴极靶面磁场水平分量的最大值为0.2344T,相比2Cr13作铁芯磁场水平分量最大值增加了14.8%。有关铁磁材料的低温磁性能研究可以为超导电磁装置的铁芯磁路设计提供依据。     

Linear stability of double-diffusive convection in a micropolar ferromagnetic fluid saturating a porous medium

This paper deals with the theoretical investigation of the double-diffusive convection in a micropolar ferromagnetic fluid layer heated and soluted from below saturating a porous medium subjected to a transverse uniform magnetic field. For a flat fluid layer contained between two free boundaries, an exact solution is obtained. A linear stability analysis theory and normal mode analysis method have been carried out to study the onset of convection. The influence of various parameters like medium permeability, solute gradient, non-buoyancy magnetization and micropolar parameters (i.e. coupling parameter, spin diffusion parameter and micropolar heat conduction parameter) has been analyzed on the onset of stationary convection. The critical magnetic thermal Rayleigh number for the onset of instability is also determined numerically for sufficiently large values of buoyancy magnetization parameter M₁ and results are depicted graphically. The principle of exchange of stabilities is found to hold true for the micropolar ferromagnetic fluid saturating a porous medium heated from below in the absence of micropolar viscous effect, microinertia and solute gradient. The oscillatory modes are introduced due to the presence of the micropolar viscous effect, microinertia and solute gradient, which were non-existent in their absence. In this paper, an attempt is also made to obtain the sufficient conditions for the non-existence of overstability.     

磁偶极子链与磁粉探伤

磁偶极子链假说是在对磁粉探伤与磁偶极子理论作系统研究中发展起来的，简介磁偶极子链的定义、种类、特性和功能，从而利用这一新概念解决了一系列磁粉探伤中的理论难题。     

汽轮机转子的运输磁化

根据汽轮机转子在铁路运输中的机械振动和铁磁性材料磁化－退磁过程中的能量变化，阐明汽轮机转子由北向南长途径运输后自发强烈磁化的原因。     

A study on swift (∼100 MeV) heavy ion irradiated Ni films on Si substrates

Ni thin films (∼50 nm) on silicon substrates have been irradiated from 100 MeV swift heavy ions of Fe⁷⁺ with a fluence of 10¹² ions cm⁻². SEM studies show a nice feature of interwoven grains which looks like a knitted network which has been resolved as a spherical grainy structure from AFM studies. Chemical phase identification of the grains has been done from XRD studies and it is found that there is a formation of the Ni₂Si silicide phase having average grain size of ∼70 nm. The devices have also been characterized from I-V characteristics before and after the irradiation at varying temperature from LN₂ to room temperature. The current across the irradiated interface has increased by two orders of magnitude as compared to the unirradiated ones and show a nearly temperature independent behaviour. MR (magnetoresistance) has been studied from the current flow data in magnetic fields up to 10 kG. Unirradiated devices do not show any effect on current transport in external magnetic field. M-H characteristics of the irradiated devices show the typical magnetic behaviour of nano particles like superparamagnetic behaviour. The MR features has been related to the M-H variations. The observed results show the formation of magnetic nano grains due to interfacial intermixing in these devices of Ni/n-Si. The role of swift heavy ions for nano grain fabrication has been discussed and the observed properties have been understood by considering the formation of a nano magnetic granular phase.     

Design and experimental investigation of composite squirrel cage rotor with temperature effects

Fiber reinforced composite material and magnetic powder containing epoxy composite were employed for the materials of the spindle shaft and squirrel cage rotor, respectively to enhance the dynamic performance of high speed built-in type air spindle system because the bending natural frequency of spindle system increases when the specific bending stiffness (EI/ρ) of the shaft is high and rotor mass is reduced. Although polymer based composite rotors have low eddy current characteristics, the mechanical and magnetic properties of the composite rotor at elevated temperatures may be degraded due to the heat transfer from stator coils.

Therefore, in this paper, the mechanical and magnetic material properties of powder containing composites such as storage modulus (E), coefficient of thermal expansion (), thermal conductivity (k) and magnetization curves (B–H curves) were measured with respect to temperature and magnetic powder content. Then the thermal and magnetic analyses were performed with appropriate boundary and loading conditions, and the optimal design conditions of squirrel cage rotor were proposed.     

蒸馏技术发展现状

综述了蒸馏技术的发展现状,认为蒸馏技术发展的着眼点是开发成本低,投资少的清洁技术。     

Effect of heat treatment on the magnetic properties of nanocrystalline spinel Li–Ni ferrite prepared by a simple soft chemistry route

A simple soft chemistry route was developed to synthesize nanocrystalline Li–Ni ferrite (Li_0.25Ni_0.5Fe_2.25O₄). The as-prepared ferrite samples were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The effects of the annealing temperature on the particle sizes and magnetic properties of the synthesized Li–Ni ferrites were investigated. The results indicated that the ferrite samples obtained by this method had the single-phase spinel structure. Particle sizes estimated from Scherrer's formula increased with the annealing temperature. The magnetic properties of the ferrite samples showed strong dependence on the annealing temperature. The coercivity initially increased and then decreased with increasing annealing temperature whereas the saturation magnetization continuously increased.