Dissipation in ferrofluids: Mesoscopic versus hydrodynamic theory

Part of the field dependent dissipation in ferrofluids occurs due to the rotational motion of the ferromagnetic grains relative to the viscous flow of the carrier fluid. The classical theoretical description due to Shliomis uses a mesoscopic treatment of the particle motion to derive a relaxation equation for the non-equilibrium part of the magnetization. Complementary, the hydrodynamic approach of Liu involves only macroscopic quantities and results in dissipative Maxwell equations for the magnetic fields in the ferrofluid. Different stress tensors and constitutive equations lead to deviating theoretical predictions in those situations, where the magnetic relaxation processes cannot be considered instantaneous on the hydrodynamic time scale. We quantify these differences for two situations of experimental relevance namely a resting fluid in an oscillating oblique field and the damping of parametrically excited surface waves. The possibilities of an experimental differentiation between the two theoretical approaches is discussed.Comment: 14 pages, 2 figures, to appear in PR

ENSURING OF RADIATION PROTECTION DURING WORKS ON TRANSFORMATION OF THE OBJECT SHELTER INTO ECOLOGICALLY SAFE SYSTEM. BIOPHYSICAL MONITORING OF THE PERSONNEL INTERNAL EXPOSURE DOSES

Given paper, states the ensuring of the interpretation of the basic radiation protection principles, relative to the works at the Object Shelter (OS). Analysis of the factors of radiation situation at the OS is figured out. Functioning at the present time individual dose monitoring (IDM) system at the OS is describe. The system is based on the methods of biophysical monitoring. A series of the results, obtained during internal exposure individual dose monitoring of the personnel is presented. It is mentioned, that implementation of the internal exposure dose biophysical monitoring system (during the works on transformation of the OS into ecologically safe system) allows:  provide adequate level of the IDM of the internal exposure dose (the level is corresponds to the present day requirements of the radiation protection); develop the recommendations on selection of individual means of protection of respiratory tract; ensure determination of the parameters of radioactive air contamination in the work areas; and, provide the optimal planning of dose load to the personnel

A structured approach for the assessment of internal dose: The IDEAS guidelines

The need for harmonisation of the procedures for internal dose assessment has been recognised within an EU research project under the 5th Framework Programme. The aim of the IDEAS project was to develop general guidelines for standardising assessments of intakes and internal doses. It started in October 2001 and ended in June 2005. The project is closely related to some goals of the work of Committee 2 of the International Commission on Radiological Protection and since 2003 there has been close co-operation between the two groups. The general philosophy of the guidelines is focusing on the principles of harmonisation, accuracy and proportionality. The proposed system of 'level of task' to structure the approach of internal dose evaluation is also reported. Some details of the internal structure of the guidelines for the different pathways of intake are provided. © The Author 2007. Published by Oxford University Press. All rights reserved