Transformation Thermotics and Extended Theories

This open access book describes the theory of transformation thermotics and its extended theories for the active control of macroscopic thermal phenomena of artificial systems, which is in sharp contrast to classical thermodynamics comprising the four thermodynamic laws for the passive description of macroscopic thermal phenomena of natural systems. This monograph consists of two parts, i.e., inside and outside metamaterials, and covers the basic concepts and mathematical methods, which are necessary to understand the thermal problems extensively investigated in physics, but also in other disciplines of engineering and materials. The analyses rely on models solved by analytical techniques accompanied by computer simulations and laboratory experiments. This monograph can not only be a bridge linking three first-class disciplines, i.e., physics, thermophysics, and materials science, but also contribute to interdisciplinary development

Transformation Thermotics and Extended Theories

This open access book describes the theory of transformation thermotics and its extended theories for the active control of macroscopic thermal phenomena of artificial systems, which is in sharp contrast to classical thermodynamics comprising the four thermodynamic laws for the passive description of macroscopic thermal phenomena of natural systems. This monograph consists of two parts, i.e., inside and outside metamaterials, and covers the basic concepts and mathematical methods, which are necessary to understand the thermal problems extensively investigated in physics, but also in other disciplines of engineering and materials. The analyses rely on models solved by analytical techniques accompanied by computer simulations and laboratory experiments. This monograph can not only be a bridge linking three first-class disciplines, i.e., physics, thermophysics, and materials science, but also contribute to interdisciplinary development

Diffusion metamaterials for plasma transport

Plasma technology has found widespread applications in numerous domains, yet the techniques to manipulate plasma transport predominantly rely on magnetic control. In this review, we present a streamlined diffusion-migration method to characterize plasma transport. Based on this framework, the viability of the transformation theory for plasma transport is demonstrated. Highlighted within are three model devices designed to cloak, concentrate, and rotate plasmas without significantly altering the density profile of background plasmas. Additionally, insights regarding potential implications for novel physics are discussed. This review aims to contribute to advancements in plasma technology, especially in sectors like medicine and chemistry.Comment: For more details, see Chapter 15 of the forthcoming Springer monograph entitled "Diffusionics: Diffusion Process Controlled by Diffusion Metamaterials.

On electromagnetic and quantum invisibility

The principle objective of this dissertation is to investigate the fundamental properties of electromagnetic wave interactions with artificially fabricated materials i.e., metamaterials for application in advanced stealth technology called electromagnetic cloaking. The main goal is to theoretically design a metamaterial shell around an object that completely eliminates the dipolar and higher order multipolar scattering, thus making the object invisible. In this context, we developed a quasi-effective medium theory that determines the optical properties of multi-layered-composites beyond the quasi-static limit. The proposed theory exactly reproduces the far-field scattering/extinction cross sections through an iterative process in which mode-dependent quasi-effective impedances of the composite system are introduced. In the large wavelength limit, our theory is consistent with Maxwell-Garnett formalism. Possible applications in determining the hybridization particle resonances of multi-shell structures and electromagnetic cloaking are identified. This dissertation proposes a multi-shell generic cloaking system. A transparency condition independent of the object\u27s optical and geometrical properties is proposed in the quasi-static regime of operation. The suppression of dipolar scattering is demonstrated in both cylindrically and spherically symmetric systems. A realistic tunable low-loss shell design is proposed based on the composite metal-dielectric shell. The effects due to dissipation and dispersion on the overall scattering cross-section are thoroughly evaluated. It is shown that a strong reduction of scattering by a factor of up to 103 can be achieved across the entire optical spectrum. Full wave numerical simulations for complex shaped particle are performed to validate the analytical theory. The proposed design does not require optical magnetism and is generic in the sense that it is independent of the object\u27s material and geometrical properties. A generic quantum cloak analogous to the optical cloak is also proposed. The transparency conditions required for the shells to cloak an object impinged by a low energy beam of particles are derived. A realistic cloaking system with semiconductor material shells is studied

Roadmap on Transformation Optics

Transformation Optics asks Maxwell's equations what kind of electromagnetic medium recreate some smooth deformation of space. The guiding principle is Einstein's principle of covariance: that any physical theory must take the same form in any coordinate system. This requirement fixes very precisely the required electromagnetic medium. The impact of this insight cannot be overestimated. Many practitioners were used to thinking that only a few analytic solutions to Maxwell's equations existed, such as the monochromatic plane wave in a homogeneous, isotropic medium. At a stroke, Transformation Optics increases that landscape from `few' to `infinity', and to each of the infinitude of analytic solutions dreamt up by the researcher, corresponds an electromagnetic medium capable of reproducing that solution precisely. The most striking example is the electromagnetic cloak, thought to be an unreachable dream of science fiction writers, but realised in the laboratory a few months after the papers proposing the possibility were published. But the practical challenges are considerable, requiring meta-media that are at once electrically and magnetically inhomogeneous and anisotropic. How far have we come since the first demonstrations over a decade ago? And what does the future hold? If the wizardry of perfect macroscopic optical invisibility still eludes us in practice, then what compromises still enable us to create interesting, useful, devices? While 3D cloaking remains a significant technical challenge, much progress has been made in 2- dimensions. Carpet cloaking, wherein an object is hidden under a surface that appears optically flat, relaxes the constraints of extreme electromagnetic parameters. Surface wave cloaking guides sub-wavelength surface waves, making uneven surfaces appear flat. Two dimensions is also the setting in which conformal and complex coordinate transformations are realisable, and the possibilities in this restricted domain do not appear to have been exhausted yet. Beyond cloaking, the enhanced electromagnetic landscape provided by Transformation Optics has shown how fully analytic solutions can be found to a number of physical scenarios such as plasmonic systems used in electron energy loss spectroscopy (EELS) and cathodoluminescence (CL). Are there further fields to be enriched? A new twist to Transformation Optics was the extension to the space-time domain. By applying transformations to space-time, rather than just space, it was shown that events rather than objects could be hidden from view; Transformation Optics had provided a means of effectively redacting events from history. The hype quickly settled into serious nonlinear optical experiments that demonstrated the soundness of the idea, and it is now possible to consider the practical implications, particularly in optical signal processing, of having an `interrupt-without-interrupt' facility that the so-called temporal cloak provides. Inevitable issues of dispersion in actual systems have only begun to be addressed. Now that time is included in the programme of Transformation Optics, it is natural to ask what role ideas from General Relativity can play in shaping the future of Transformation Optics. Indeed, one of the earliest papers on Transformation Optics was provocatively titled `General Relativity in Electrical Engineering'. The answer that curvature does not enter directly into transformation optics merely encourages us to speculate on the role of Transformation Optics in defining laboratory analogues. Quite why Maxwell's theory defines a `perfect' transformation theory, while other areas of physics such as acoustics are not apparently quite so amenable, is a deep question whose precise, mathematical answer will help inform us of the extent to which similar ideas can be extended to other fields. The contributors to this roadmap review, who are all renowned practitioners or inventors of Transformation Optics, will give their perspectives into the field's status and future development

Advanced thermal metamaterials design for thermal management systems

Heat is a by-product of any electronic circuit. It is unavoidable; however, an adequate thermal management system can protect thermal sensitive components from catastrophic failure. Thermal cloaking, based on thermal metamaterials, makes the thermal sensitive components invisible to thermal flow and protects them from overheating. This study developed two novel thermal metamaterials using the hybrid conduction-convection phenomena. The designed thermal metamaterials have two distinct properties. Firstly, it makes thermal sensitive components invisible within the cloak zone and protects them from heat flux. Secondly, it keeps the temperature in the cloak zone low for an extended duration which is not achievable by conventional thermal metamaterials. Using the designed thermal metamaterials, any thermal sensitive components can be protected from overheating and perform at their optimum even during extensive computations. The first thermal metamaterial design is based on natural convection-assisted thermal cloaking, whereas the other is based on forced convection-assisted thermal cloaking. Experiments were used to validate the simulation results under natural convection, corresponding to the simulation assumptions. Results showed that the temperature within the cloak region could be reduced by up to 15oC. At the same time, the heat source remains at 100oC and the heat sink at 0oC, from ~50oC with traditional cloaking to 35oC with the developed hybrid conduction-convection thermal metamaterial. It is worth mentioning that the experimental results matched well with the FEM simulation results. Another contribution of this study is the incorporation of the proposed hybrid conduction-convection thermal metamaterial (natural convection based) onto a printed circuit board (PCB). Its performance is evaluated using a custom-designed temperature sensor circuit. One sensor is shielded by thermal cloaking, while the other is left exposed. Experiments were carried out under both open and closed cover conditions. Due to the novel and optimized thermal metamaterial, the sensor placed within the cloaked region remained at a low temperature of around 37oC compared to the open sensor at about 48oC in the enclosed box. Furthermore, a novel optimisation approach is devised using the Conjugate gradient method (CGM) and adjoint equations. It is used to solve the inverse heat conduction problem (IHCP) and predict anisotropic thermal conductivity distribution for perfect thermal cloaking. Using the optimisation algorithm, a squared shape thermal cloak with uniform and consistent temperature below 30oC was achieved within the first ten iterations with excellent stability. Unlike coordinate transformation, this approach offered a novel thermal metamaterial independent of the base material's thermal conductivity and the cloak's shape. This study provided novel thermal metamaterial designs that can realize thermal cloaking while keeping the temperature in the cloak zone within a safe range, particularly for thermal sensitive components. It is expected to shift thermal cloaking closer to being used in advanced electronic devices such as laptops, smartphones, electric cars, drones, etc

Cloaking and invisibility: A review

Invisibility has been a tantalizing concept for mankind over several centuries. With recent developments in metamaterial science and nanotechnology, the possibility of cloaking objects to incoming electromagnetic radiation has been escaping the realm of science fiction to become a technological reality. In this article, we review the state-of-the-art in the science of invisibility for electromagnetic waves, and examine the different available technical concepts and experimental investigations, focusing on the underlying physics and the basic scientific concepts. We discuss the available cloaking methods, including transformation optics, plasmonic and mantle cloaking, transmission-line networks, parallel-plate cloaking, anomalous resonance methods, hybrid methods and active schemes, and give our perspective on the subject and its future. We also draw a parallel with cloaking research for acoustic and elastodynamic waves, liquid waves, matter waves and thermal flux, demonstrating how ideas initiated in the field of electromagnetism have been able to open ground breaking venues in a variety of other scientific fields. Finally, applications of cloaking to non-invasive sensing are discussed and reviewed

Analysis and Reduction of the Scattering by Cloaked Metallic Cylinders Beyond the Quasi-static Limit

L'abstract è presente nell'allegato / the abstract is in the attachmen