Search results for "Heat capacity"
showing 10 items of 90 documents
Application of Mathematical Models in Analysis of Heat Losses in the Buildings
2006
Physical model of heat balance for separate living room is discussed, which allows to analyse the distributions of the flow of air and temperature depending on the physical conditions and geometry. The model enables to choose the optimal surface area of building elements and their properties in order to decrease the heat losses and improve the conditions of thermal comfort. Room with bounding constructions and real dimensions is modelled that helps to understand the peculiarities of heat transfer process in the room as well as distribution of various characteristic quantities and their dependence on the different conditions. Multiple parameters are varied in 2D calculations and their influe…
Effects of solarisation on soil thermal-physical properties under different soil treatments: A review
2020
Solarisation technology allows for improving soil quality as well as crop productivity. The influence of the properties and method of use of plastic materials used to cover soils, such as the number and thickness of layers, and colour of the material, significantly alters soil thermal-physical properties. These effects can be managed and modified to increase solarisation efficiency by achieving a decrease in vapour movement between the soil surface and the atmosphere. Also, soil solarisation establishes microclimates that increase the effectiveness of fertilisers, thus modifying the soil thermal-physical properties. However, there is a lack of complete and general overview of this widely us…
A hybrid method for calorimetry with subnanoliter samples using Schottky junctions
2007
A μm-scale calorimeter realized by using Schottky junctions as a thermometer is presented. Combined with a hybrid experimental method, it enables simultaneous time-resolved measurements of variations in both the energy and the heat capacity of subnanoliter samples.
Thermal- and photoinduced spin-state switching in an unprecedented three-dimensional bimetallic coordination polymer.
2005
The compound {Fe(pmd)[Ag(CN)2][Ag2(CN)3]} (pmd=pyrimidine) was synthesized and characterized. Magnetic, calorimetric and single crystal visible spectroscopic studies demonstrate the occurrence of a two-step high-spin (HS) right arrow over left arrow low-spin (LS) transition. The critical temperatures are T(c1)=185 and T(c2)=148 K. Each step involves approximately 50 % of the iron centers, with the low-temperature step showing a hysteresis of 2.5 K. The enthalpy and entropy variations associated with the two steps are DeltaH(1)=3.6+/-0.4 kJ mol(-1) and DeltaS(1)=19.5+/-3 J K(-1) mol(-1); DeltaH(2)=4.8+/-0.4 kJ mol(-1) and DeltaS(2)=33.5+/-3 J K(-1) mol(-1). Photomagnetic and visible spectros…
Heat capacity of small superconducting disks
2000
Abstract The superconducting state of small samples in a magnetic field is strongly dependent on the sample dimensions and geometry. We have initiated measurements of heat capacity of small superconducting disks. Our method, extensively used in many of our related experiments, is to measure the thermal time constant as a function of temperature of disks on a thin silicon nitride membrane. Theoretical results on heat capacity of the disks based on the Ginzburg–Landau theory will be presented.
Heat Capacity of Mesoscopic Superconducting Disks
1999
We study the heat capacity of isolated giant vortex states, which are good angular momentum ($L$) states, in a mesoscopic superconducting disk using the Ginzburg-Landau (GL) theory. At small magnetic fields the $L$=0 state qualitatively behaves like the bulk sample characterized by a discontinuity in heat capacity at $T_c$. As the field is increased the discontinuity slowly turns into a continuous change which is a finite size effect. The higher $L$ states show a continuous change in heat capacity at $T_c$ at all fields. We also show that for these higher $L$ states, the behavior of the peak position with change in field is related to the paramagnetic Meissner effect (irreversible) and can …
Collective amplitude mode fluctuations in a flat band superconductor formed at a semimetal surface
2016
We study the fluctuations of the amplitude (i.e., the Higgs-Anderson) mode in a superconducting system of coupled Dirac particles proposed as a model for possible surface or interface superconductivity in rhombohedral graphite. This system also serves as a generic model of a topological semimetal with an interaction-driven transition on its surface. We show that the absence of Fermi energy and vanishing of the excitation gap of the collective amplitude mode in the model leads to a large fluctuation contribution to thermodynamic quantities, such as the heat capacity. As a consequence, the mean-field theory becomes inaccurate, indicating that the interactions lead to a strongly correlated sta…
Heat capacities and volumes of suspensions in the presence of surfactants
2004
Abstract Density and heat capacity measurements of water–surfactant–silica ternary systems were carried out as functions of the silica and the surfactant concentrations at 298 K. From these properties, the apparent molar volume and heat capacity of the surfactant in a given water+silica mixture were evaluated. As well, the apparent specific volume and heat capacity of silica, at a given concentration, in the water+surfactant mixtures as functions of the surfactant concentration were calculated. Some surfactants (decyltrimethylammonium bromide, sodium octanoate, sodium decanoate, sodium dodecanoate, sodium decylsulfate, sodium perfluorooctanoate and N , N -dimethyldodecylamine- N -oxide) wer…
Thermal properties of multiferroic Bi1−xEuxFeO3 (х = 0–0.40) ceramics
2017
Abstract A study of thermal diffusion, heat capacity and thermal conductivity of multiferroic Bi 1−x Eu x FeO 3 (x = 0–0.4) within the range of 130–1200 K is reported. Modifying by admixture of Eu is found to change substantially the thermal anomalies of diffusion and thermal conductivity of the antiferromagnetic phase transition, to increase heat capacity over a wide range of temperatures and to shift the antiferromagnetic transition temperature. The excess heat capacity is shown being related to Schottky effect of three-level states. The mechanisms dominating thermal transfer of phonons at the phase transition and dependence of the mean free path of phonons on the temperature are determin…
Ground state properties of SmB6
2002
Abstract We have studied the ground state properties of the intermediate valence narrow-gap semiconductor SmB 6 by means of point-contact (PC) spectroscopy and specific heat measurements. The density of states derived from PC tunneling spectra could be decomposed into two energy-dependent parts with E g =21 meV and E d =4.5 meV wide gaps, and a finite residual density of states at the Fermi level. The specific heat of SmB 6 is enhanced below about 2 K, more pronounced for the sample with less impurities. This behavior can be attributed to the formation of a coherent state within the residual density of states in the energy gap.