Search results for "Thermal"
showing 10 items of 3576 documents
Calorimetric investigation of the vulcanization of factice
1991
Sulphur factice is produced from a mixture of a vegetable oil and sulphur at temperatures between 130 and 160‡C. The slow exothermal vulcanization results in rubber-like elastomers. We have developed an isothermal calorimeter for measurements both in the liquid and the solid state and simulated the production process at the laboratory scale. The compensating calorimeter consists of a hot plate equipped with thin aluminium rods descending into a Dewar vessel. Besides optimization of the temperature control, remarkable savings of time were achieved by previous elaidinization of the oil using hydrosulphide.
Symmetric logarithmic derivative of Fermionic Gaussian states
2018
In this article we derive a closed form expression for the symmetric logarithmic derivative of Fermionic Gaussian states. This provides a direct way of computing the quantum Fisher Information for Fermionic Gaussian states. Applications ranges from quantum Metrology with thermal states and non-equilibrium steady states with Fermionic many-body systems.
Mass transfer in nonisothermal ferrocolloids under the effect of a magnetic field
1999
Abstract The paper presents a review of newest experimental results on particle thermal diffusion in hydrocarbon based ferrofluids. The measurements are performed using a vertical thermal diffusion column, the Soret coefficient is evaluated from particle separation curves employing a simple column theory which accounts for thermal convection in the vertical channel forced by a concentration buoyancy force arising during the thermophoretic transfer of heavy particles. High positive values of the Soret coefficient of lyophilized Fe 3 O 4 and Mn x Zn 1− x Fe 2 O 4 particles in surfacted tetradecane based colloids are measured. Experiments confirm the theoretically predicted anisotropy of parti…
Thermoosmotic transfer of sterically stabilized ferrofluid particles in non-isothermal capillary porous layer
2005
Experiments on thermodiffusive transfer of ferrofluid nanoparticles in capillary porous layer are presented. The layer consists of a number of capillary filter sheets pressed between two plates of different temperatures. Steady profiles of particle concentration are detected after the experiment from magnetization of each filter sheet. It is shown that particle separation in porous layer is remarkably influenced by thermoosmotic forces. The observed effect is different for colloids of various surfactants and of various carrier liquids.
Non-isothermal mass transfer of ferrocolloids through porous membrane
2011
Abstract The present paper deals with transport properties of ferrofluid nanoparticles in non-isothermal capillary-porous layer. Experiment establishes that the temperature difference, which is applied across the layer, induces a thermoosmotic pressure gradient directed toward increasing temperature. The measurement results are interpreted in a frame of phenomenology of linear irreversible thermodynamics. The transport coefficients are evaluated comparing the measured separation curves with approximate solution of the corresponding mass transfer problem.
Transport properties of an ionic magnetic colloid: experimental study of increasing the ionic strength
2002
Abstract The phase separation of an ionic magnetic colloid in zero magnetic field by increasing the ionic strength is well known [Universite Paris VI, France, 1987; J. Colloid Interface Sci. 132 (1989) 1]. The present work deals with investigation of an ionic ferrofluid by increasing the ionic strength in the range of 0–0.14 mol/l, being safely below the threshold value at which the effect of phase separation occurs. By the optical grid setup [Fourth International conference PAMIR, France, 2000], the main transport properties of a ferrofluid, i.e. translational mass diffusion and thermal diffusion (Soret) coefficients, are measured. The obtained results show a strong dependence of mass diff…
{CoIII2DyIII2} single molecule magnet with two resolved thermal activated magnetization relaxation pathways at zero field
2014
The new complex [CoIII2DyIII 2(OMe)2(teaH)2(Piv)6] in the {CoIII2DyIII2} family, shows two well resolved thermal activated magnetization relaxation pathways under AC experiments in zero DC field. Fitted crystal field parameters suggest that the origin of these two pathways relies on two different excited mJ sub-levels. Fil: Funes, Víctor Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina …
Relaxation of the order-parameter statistics and dynamical confinement
2020
We study the relaxation of the local ferromagnetic order in the quantum Ising chain in a slant field with both longitudinal and transverse components. After preparing the system in a fully polarised state, we analyse the time evolution of the entire probability distribution function (PDF) of the magnetisation within a block of $\ell$ spins. We first analyse the effect of confinement on the gaussification of the PDF for large $\ell$, showing that the melting of initial order is suppressed when the longitudinal field is aligned to initial magnetisation while it is sped up when it is in the opposite direction. Then we study the thermalisation dynamics. In the paramagnetic region, the PDF quick…
Polarization of SrBi 2 Ta 2 O 9 ceramics at infra‐low frequencies
2009
Dielectric response in the SrBi2Ta2O9 ceramics is studied over a wide range of temperatures at fields up to Emax ≈ 18 kV/cm. Dependence of dielectric permittivity on field intensity is analyzed at different temperatures. A series of polarization loops are obtained at frequencies 0.1 Hz, 1 Hz, and 10 Hz. The hysteresis at switching polarization is displayed by the shape of polarization loops changing with the field amplitude from bi-angles to quasi-saturated loop patterns of a high degree of rectangularity. The ratio of remnant polarization to maximum polarization as function of field amplitude is presented. Thermal behaviour of the coercive field and the half-width of polarization loops is …
Thermal and rheological characterisation of a thermoset matrix for filament winding modelling
2004
Rheo-kinetic behaviour of an epoxy resin, coupled with an aliphatic polyamines hardener, used in fibre reinforced plastics, was analysed comparing experimental data to theoretical models. Then the modelling of technological filament winding process for thermoset matrix composites, developed through a numerical code realized with MATLAB, is reported. The model includes winding and curing phase decoupling the manufacturing process into sub-models. Four sub-models are used: fibre motion, thermal, kinetic and rheological model. Considerable differences are obtained in process condition, using several thermal treatments. The numerical modelling helps to detect the process conditions to optimise…