Search results for "thermal [correlation function]"

2012

classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonic behavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The eect of a Levy noise generated by a Cauchy‐Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonant activation and noise enhanced stability…

Nonlinear relaxation phenomena in metastable condensed matter systems

2016

Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced s…

Boosting the performance of a Reverse Electrodialysis – Multi-Effect Distillation Heat Engine by novel solutions and operating conditions

2019

Abstract This work presents a performance analysis of a waste-heat-to-power Reverse Electrodialysis Heat Engine (RED-HE) with a Multi-Effect Distillation (MED) unit as the regeneration stage. The performance of the system is comparatively evaluated using two different salts, sodium chloride and potassium acetate, and investigating the impact of different working solutions concentration and temperature in the RED unit. For both salt solutions, the impact of membrane properties on the system efficiency is analysed by considering reference ionic exchange membranes and high-performing membranes. Detailed mathematical models for the RED and MED units have been used to predict the thermal efficie…

In-plane conductive heat tansfer in solid and porous planar structures

2011

Methods for determining the in-plane thermal diffusivity in a planar sample geometry were developed. These methods were tested and verified by measuring planar metal samples with known thermal properties. The techniques used were based on heating the sample at one edge and recording the evolution of the temperature field in the sample by a thermographic camera. The temperature fields at different times were processed and then fitted by a solution to a heat equation describing the experimental setup, thermal diffusivity as one of the fitting parameters. In the first experimental setup the sample was placed in a weak constant flow of air, and the situation was improved in the second setup by …

A geostatistical approach to map near-surface soil moisture through hyperspatial resolution thermal inertia.

2021

Thermal inertia has been applied to map soil water content exploiting remote sensing data in the short and long wave regions of the electromagnetic spectrum. Over the last years, optical and thermal cameras were sufficiently miniaturized to be loaded onboard of unmanned aerial systems (UASs), which provide unprecedented potentials to derive hyperspatial resolution thermal inertia for soil water content mapping. In this study, we apply a simplification of thermal inertia, the apparent thermal inertia (ATI), over pixels where underlying thermal inertia hypotheses are fulfilled (unshaded bare soil). Then, a kriging algorithm is used to spatialize the ATI to get a soil water content map. The pr…

Prussian Blue Analogues of Reduced Dimensionality

2012

Abstract: Mixed-valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room-temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real devices depends primarily on higher-order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced-dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is …

Organobase-Catalyzed Synthesis of Multiarm Star Polylactide With Hyperbranched Poly(ethylene glycol) as the Core

2011

Multiarm star copolymers consisting of the polyether-polyol hyperbranched poly(ethylene glycol) (hbPEG) as core and poly(L-lactide) (PLLA) arms are synthesized via the organobase- catalyzed ring-opening polymerization of lactide using hbPEG as a multifunctional macroinitiator. Star copolymers with high molecular weights up to 792 000 g mol−1 are prepared. Detailed 2D NMR analysis provides evidence for the attachment of the PLLA arms to the core and reveals that the adjustment of the monomer/initiator ratio enables control of the arm length. Size exclusion chromatography measurements show narrow molecular weight distributions. Thermal analysis reveals a lower glass transition temperature, me…

Comparison of two melting range analysis methods with lactitol monohydrate

2001

Abstract In pharmacopoeia, the melting point is determined by a standard method with a melting point instrument. The melting point can also be determined with differential scanning calorimetry (DSC). In this study, the standard method and DSC method are compared for determining the melting range of lactitol monohydrate. The effect of initial temperature, grinding, and drying on the melting range of different lactitol monohydrate samples was studied by a melting point instrument. The melting point and melting enthalpy of the stable form of lactitol monohydrate was identified by DSC. The statistical analysis of the results is based on a t-test. All studied variables had a small effect on the …

Urban morphology detection and it's linking with land surface temperature: A case study for Tehran Metropolis, Iran

2021

Abstract Expansion of urban areas and alteration of natural land cover exacerbate the local climate change. To find out the effect of land cover changes on the local climate, in this study, the Local Climate Zone (LCZ) concept was utilized to detect urban morphology in Tehran Metropolis. LCZ and Land Surface Temperature (LST) can be identified and classified based on available remote sensing products. Firstly, LCZ maps of Tehran metropolis were extracted using Landsat imagery, and secondly, relationships between LCZ and LST were explored for three years (1990, 2004, and 2018). We found that Tehran urban structure has 13 LCZs based on imagery from Landsat 5 and 14 LCZs based on images for La…

Zeolite-gas systems and solar refrigeration : a study of the adsorptive properties at high pressures in the R22 freon-13X zeolite and ammonia-13X zeo…

1990

The adsorption of ammonia and R22 freon on 13X zeolite was studied in the conditions of possible use of these fluids in heat machines for solar refrigeration. The ranges of temperature and pressure, investigated in this study, extended from 0 to 80 °C and from 10-1 to 6 105 Pa respectively. The adsorption isotherms were collected by microgravimetry using a thermobalance specially built to be used in aggressive gases at pressures up to 106 Pa. Weak hysteresis was detected when ammonia was desorbed below 80 °C. A critical study concerning both applicability of classical adsorption equations (Dubinin-Radushkevitch and Langmuir) and comparison with other zeolite-gas systems is presented. Compar…