60,118 research outputs found
Novel thick-foam ferroelectret with engineered voids for energy harvesting applications
This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications
PDMS/PVA composite ferroelectret for improved energy harvesting performance
This paper address the PDMS ferroelectret discharge issue for improved long- term energy harvesting performance. The PDMS/PVA ferroelectret is fabricated using a 3D-printed plastic mould technology and a functional PVA composite layer is introduced. The PDMS/PVA composite ferroelectret achieved 80% piezoelectric coefficient d33 remaining, compared with 40% without the proposed layer over 72 hours. Further, the retained percentage of output voltage is about 73% over 72 hours
Modelling thermomechanical behaviour of Cr-Mo-V steel
This paper presents a mechanism-based approach for modelling the thermomechanical behaviour of a Cr-Mo-V steel. A set of unified viscoplastic constitutive equations were employed to model dislocation density, recrystallisation and grain size during deformation. The evolution of dislocation density accounts for the build-up of dislocations due to plastic strain, the static and dynamic recovery and the effect of recrystallisation. Recrystallisation occurs when a critical dislocation density is reached after an incubation time, and grain size becomes smaller after such event. Gleeble compression tests were used to obtain Stress-strain curves and evaluate the microstructural evolution at different temperature and strain rate, and the material constants for the model were determined from the experimental data. Copyright © 2010 MS&T10®
Theory of selective excitation in Stimulated Raman Scattering
A semiclassical model is used to investigate the possibility of selectively
exciting one of two closely spaced, uncoupled Raman transitions. The duration
of the intense pump pulse that creates the Raman coherence is shorter than the
vibrational period of a molecule (impulsive regime of interaction). Pulse
shapes are found that provide either enhancement or suppression of particular
vibrational excitations.Comment: RevTeX4,10 pages, 5 figures, submitted to Phys.Rev.
The Droplet State and the Compressibility Anomaly in Dilute 2D Electron Systems
We investigate the space distribution of carrier density and the
compressibility of two-dimensional (2D) electron systems by using the local
density approximation. The strong correlation is simulated by the local
exchange and correlation energies. A slowly varied disorder potential is
applied to simulate the disorder effect. We show that the compressibility
anomaly observed in 2D systems which accompanies the metal-insulator transition
can be attributed to the formation of the droplet state due to disorder effect
at low carrier densities.Comment: 4 pages, 3 figure
Variational study of U(1) and SU(2) lattice gauge theories with Gaussian states in 1+1 dimensions
We introduce a method to investigate the static and dynamic properties of
both Abelian and non-Abelian lattice gauge models in 1+1 dimensions.
Specifically, we identify a set of transformations that disentangle different
degrees of freedom, and apply a simple Gaussian variational ansatz to the
resulting Hamiltonian. To demonstrate the suitability of the method, we analyze
both static and dynamic aspects of string breaking for the U(1) and SU(2) gauge
models. We benchmark our results against tensor network simulations and observe
excellent agreement, although the number of variational parameters in the
Gaussian ansatz is much smaller.Comment: 19 pages, 6 figures. Added references and corrected typo
Solution-Processable Graphene Oxide as an Efficient Hole Injection Layer for High Luminance Organic Light-Emitting Diodes
The application of solution-processable graphene oxide (GO) as hole injection
layer in organic light-emitting diodes (OLEDs) is demonstrated. High luminance
of over 53,000 cd m-2 is obtained at only 10 V. The results will unlock a route
of applying GO in flexible OLEDs and other electrode applications.Comment: 14 pages, 3 figures, 1 tabl
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