| 1. |
- Liu, Yichao, et al.
(författare)
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An efficient plate heater with uniform surface temperature engineered with effective thermal materials
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:14, s. 17006-17015
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Tidskriftsartikel (refereegranskat)abstract
- Extended from its electromagnetic counterpart, transformation thermodynamics applied to thermal conduction equations can map a virtual geometry into a physical thermal medium, realizing the manipulation of heat flux with almost arbitrarily desired diffusion paths, which provides unprecedented opportunities to create thermal devices unconceivable or deemed impossible before. In this work we employ this technique to design an efficient plate heater that can transiently achieve a large surface of uniform temperature powered by a small thermal source. As opposed to the traditional approach of relying on the deployment of a resistor network, our approach fully takes advantage of an advanced functional material system to guide the heat flux to achieve the desired temperature heating profile. A different set of material parameters for the transformed device has been developed, offering the parametric freedom for practical applications. As a proof of concept, the proposed devices are implemented with engineered thermal materials and show desired heating behaviors consistent with numerical simulations. Unique applications for these devices can be envisioned where stringent temperature uniformity and a compact heat source are both demanded.
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| 2. |
- Ma, Yungui, et al.
(författare)
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Experimental Demonstration of a Multiphysics Cloak : Manipulating Heat Flux and Electric Current Simultaneously
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:20, s. 205501-
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Tidskriftsartikel (refereegranskat)abstract
- Invisible cloaks have been widely explored in many different physical systems but usually for a single phenomenon for one device. In this Letter we make an experimental attempt to show a multidisciplinary framework that has the capability to simultaneously respond to two different physical excitations according to predetermined scenarios. As a proof of concept, we implement an electric-thermal bifunctional device that can guide both electric current and heat flux "across" a strong 'scatterer' (air cavity) and restore their original diffusion directions as if nothing exists along the paths, thus rendering dual cloaking effects for objects placed inside the cavity. This bifunctional cloaking performance is also numerically verified for a line-source nonuniform excitation. Our results and the fabrication technique presented here will help broaden the current research scope for multiple disciplines and may pave a way to manipulate multiple flows and create new functional devices, e.g., for on-chip applications.
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| 3. |
- Ma, Yungui, et al.
(författare)
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Transformation thermodynamics : Heat flux control and device applications
- 2014
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Ingår i: 2014 XXXITH URSI GENERAL ASSEMBLY AND SCIENTIFIC SYMPOSIUM (URSI GASS). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- Extended from its electromagnetic counterpart [1,2], transformation thermodynamics applied to thermal conduction equations can map a virtual geometry into a physical thermal medium, realizing the manipulation of heat flux with almost arbitrarily desired diffusion paths, which provides unprecedented opportunities to create thermal devices unconceivable or deemed impossible before [3,4]. In this talk we report our recent work on manipulation of transient heat flux employing this technique and showed two thermal devices: a heat flux cloak and an efficient plate heater. In the cloaking device we will show that heat flux can be guided by a transformed medium to flow around a vacuum obstacle and restore its diffusion direction as if nothing inhomogeneous exists in their trajectories [5]. In the second experiment we design an efficient plate heater that can transiently achieve a large surface of uniform temperature powered by a small thermal source [6]. As opposed to the traditional approach of relying on the deployment of a resistor network, our approach fully takes advantage of an advanced functional material system to guide the heat flux to achieve the desired temperature heating profile. Our research results are good examples of the powerful application of coordinate transformation on wave/flux manipulation and may help to broaden research in acquiring extraordinary ways to control and utilize heat energy or configure novel heat devices.
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| 4. |
- Zhong, Shuomin, et al.
(författare)
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Perfect absorption in ultrathin anisotropic epsilon-near-zero metamaterials
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:2, s. 023504-
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Tidskriftsartikel (refereegranskat)abstract
- Conventionally, perfect absorption by an ultrathin material usually requires a high material loss. In this paper, this common understanding is challenged. Our analytical solution shows that an anisotropic e-near-zero thin metamaterial (MM) backed by a metallic substrate can perfectly absorb an incident plane wave at a specific angle while the MM can be arbitrarily thin and arbitrarily low-loss. The counterintuitive phenomenon is due to coherent cancelling. As a proof, we demonstrate a microwave absorber working at 5.35 GHz using low-loss meander-line MMs with a thickness of only lambda/56. An absorption peak of 95% at a 60 degrees incidence angle is obtained experimentally, which verifies the analytical results well.
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