Search results for "Heat"
showing 10 items of 2717 documents
European Energy Efficiency Evaluation Based on the Use of Super-Efficiency Under Undesirable Outputs in SBM Models
2020
Although Data Envelopment Analysis models have been intensively used for measuring efficiency, the inclusion of undesirable outputs has extended their use to analyse relevant fields such as environmental efficiency. In this context, slacks-based measure (SBM) models offer a remarkable alternative, largely due to their ability to deal with undesirable outputs. Additionally, super-efficiency evaluation in DEA is a useful complementary analysis for ranking the performance of efficient DMUs and even mandatory for dynamic efficiency evaluation. An extension to this approach in the presence of undesirable outputs is here introduced and then applied in the context of the environmental efficiency i…
Improved locally adaptive least-squares detection of differences in images
2007
We introduce a method for change detection under nonuniform changes of intensity using an improved least-squares method. A locally adaptive normalizing window is correlated with the two images, and a morphological postprocessing is then applied to isolate objects that have been added or removed from the scene. We use a modification of the least-squares solution to get rid of clutter caused by intensity changes that do not satisfy the model assumed for the least-squares solution.
Guest Editorial Three-Dimensional Displays and Visualization
2010
THREE-DIMENSIONAL (3D) imaging and display is a natural concept for humans as it is a common vision attribute of our binocular vision, perception, and brain processing. However, until recently, our experiences have been mainly limited to the technologically inferior two-dimensional (2D) as evidenced from widespread use of 2D photography, cinema, and liquid crystal or LED-display for television, computer displays, etc.
Thermal simulation of a power transformer
2019
In the article we propose a method of thermally constructive optimization of a 110/20 kV power transformer by numerical simulation (by the finite element method) of the thermal field in the transformer. The thermal simulation was done in the Comsol module called Heat Transfer Module, based on the documentation in Catia V5, and the experimental validation was done by thermography.
Numerical study of the growth conditions in an MOCVD reactor: application to the epitaxial growth of HgTe
2002
Abstract In order to analyse the epitaxial growth by metalorganic chemical vapour deposition (MOCVD) of mercury telluride, HgTe, a 2D numerical model has been developed to simulate the gas flow in a horizontal MOCVD reactor. This model takes into account the Navier–Stokes equations coupled with the heat transfer and mass transport of chemical species. For the mathematical resolution of the governing equations a commercial solver, which can be run in a conventional personal computer, has been used. The study carried out presents a discussion about the dominant growth regime in a MOCVD growth as a function of different parameters: substrate temperature, total flow, partial pressure of precurs…
Experimental and Numerical Analysis of Air Flow, Heat Transfer and Thermal Comfort in Buildings with Different Heating Systems
2016
Abstract Monitoring of temperature, humidity and air flow velocity is performed in 5 experimental buildings with the inner size of 3×3×3 m3 located in Riga, Latvia. The buildings are equipped with different heating systems, such as an air-air heat pump, air-water heat pump, capillary heating mat on the ceiling and electric heater. Numerical simulation of air flow and heat transfer by convection, conduction and radiation is carried out using OpenFOAM software and compared with experimental data. Results are analysed regarding the temperature and air flow distribution as well as thermal comfort.
Giant Anomalous Nernst Effect in Noncollinear Antiferromagnetic Mn-based Antiperovskite Nitrides
2020
The anomalous Nernst effect (ANE) - the generation of a transverse electric voltage by a longitudinal heat current in conducting ferromagnets or antiferromagnets - is an appealing approach for thermoelectric power generation in spin caloritronics. The ANE in antiferromagnets is particularly convenient for the fabrication of highly efficient and densely integrated thermopiles as lateral configurations of thermoelectric modules increase the coverage of heat source without suffering from the stray fields that are intrinsic to ferromagnets. In this work, using first-principles calculations together with a group theory analysis, we systematically investigate the spin order-dependent ANE in nonco…
Theory of warm ionized gases: Equation of state and kinetic Schottky anomaly
2013
Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiment…
Quantum effects in the dynamics of intensity-dependent two-mode two-photon models of radiation—matter interaction
1996
Abstract We study the two-photon interaction of a two-state localized system with two modes of a quantized electromagnetic or elastic field. Assuming the coupling strength and the atom-field detuning depending on the mode populations, we find that the quantum atomic dynamics manifests nonclassical features related to the specific nonlinear model investigated.
Nanoscale Heat Engine Beyond the Carnot Limit
2013
We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the efficiency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the efficiency at maximum power of up to a factor of 4 is reached, largely ex…