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Mixed Ferrites. Bang. J. Sci. Ind. Res., 2006, 41(3- membrane fouling can be reduced. The present
4), 171-180. work is devoted to investigate the
hydrodynamics in two dimensional single spacer
A. comparative studies on anomalous behaviour at filled channels. Two different configurations of
Curie point between clay additives Mn-Zn ferrites the cylindrical spacers are investigated with
and other mixed ferrites such as Mn-Zn, Ni-Zn, different channel Reynolds number. Different
Mg-Mn and Ni-Mg have been carried out in this size and shape of formation of recirculation
investigation. The changes in T c on compositions, region, upstream and downstream of the spacers
additives and manufacturing processes of such soft are closely observed. This recirculation regions
mixed ferrites have been determined from the have an important role in enhancing the mass
temperature dependent dc resistively data and the transfer in the reattachment region.
log ρ vs. (1/1000T) graphs. It is observed that the
Curie temperature is dependent on compositions, 018 ISLAM, M.S. (Dept. of Physics, Govt.
additives, manufacturing process and Bangla College, Mirpur-1, Dhaka) & ASGAR,
microstructure. Definite changes of Curie points of M.A. (Dept. of Medical Physics & Biomedical
clay additives Mn-Zn ferrites with other ferrites Engineering, Gono Bishwabidyalay, Savar,
were observed. Both the Mn-Zn ferrites and clay Dhaka). TEMPERATURE DEPENDENCE OF
additives Mn-Zn ferrites showed some changes in SATURATION MAGNETOSTRICTION OF
their T c behavior. The T c value of Mn-Zn ferrites AMORPHOUS RIBBONS HAVING
with clay additives decreases with increasing COMPOSITION Co 80-xFe xB 10Si 10 WITH x = 2, 4, 6,
additives. In the case of clay substituted Mn-Zn 8. J. Bang. Acad. Sci., 2006, 30(1), 95-99.
ferrites the decrease of Curie point can be
3+
understood by a decrease of the number of Fe Amorphous ribbons of composition Co 80-
3+
magnetic ions substituted by nonmagnetic Al xFe xB 10Si 10 with x = 2, 4, 6, 8 prepared by melt
ions on O sites of the system. spinning technique, have been investigated in
respect of their temperature and field
017 HUSSAIN, S. (Dept. of Mathematics and dependence of magnetostriction by using strain
Natural Sciences, BRAC University, 66 gauge technique. The linear magnetostriction of
Mohakhali, Dhaka).COMPUTATIONAL FLUID this cobalt and iron based amorphous ribbons
DYNAMICS STUDY OF FLOW BEHAVIOUR have been determined by rotating magnetization
IN A SINGLE SPACER FILLED MEMBRANE vector from perpendicular position to parallel
MODULE. BRAC Univ. J. 2008, V (1), 1-8. position of the magnetization direction with
respect to the direction of strain measurement.
Membrane separation processes have added a new The magnetostriction of amorphous ribbons is of
dimension to the traditional processes. The recent prime importance to determine the domain
novel development in membrane processes have structure, magnetization process, coercivity
made it possible to use various different purposes field and permeability. The observed
at economical rates with additional flexibility and magnetostriction is negative for the all
improved efficiencies. Regarding the membrane compositions, and increases in its absolute value
separation processes, concentration polarization is monotonously for decreasing content of iron.
one of the biggest problem. It causes reduction of The minimum absolute value of
permeate flux and deterioration of permeate magnetostriction corresponds to x = 8. The
quality. Accumulation of rejected species can be temperature dependence of magnetostriction
suppressed by creating back mixing from the results supports the one ion model of
membrane to the bulk of the liquid. Various magnetostrictions. Magnetic field dependence
hydrodynamic approaches have been developed for and temperature dependence of saturation
that purpose. Feed spacers can provide higher magnetostrictions are given in tabular form. The
shear rates at the membrane surface, which, results are explained in the light of this model,
promote the mixing between the bulk of the fluid where cobalt and iron have opposite
and the fluid element adjacent to the membrane contributions in respect of sign of the
surface. As a result concentration polarization and magnetostrictive strain.
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