Fog/edge computing has been proposed to be integrated with Internet of Things (IoT) to enable computing services devices deployed at network edge, aiming to improve the user’s experience and resilience of the services in case of failures. With the advantage of distributed architecture and close to end-users, fog/edge computing can provide faster response and greater quality of service for IoT applications. Thus, fog/edge computing-based IoT becomes future infrastructure on IoT development. To develop fog/edge computing-based IoT infrastructure, the architecture, enabling techniques, and issues related to IoT should be investigated first, and then the integration of fog/edge computing and IoT should be explored. To this end, this paper conducts a comprehensive overview of IoT with respect to system architecture, enabling technologies, security and privacy issues, and present the integration of fog/edge computing and IoT, and applications. Particularly, this paper first explores the relationship between cyber-physical systems and IoT, both of which play important roles in realizing an intelligent cyber-physical world. Then, existing architectures, enabling technologies, and security and privacy issues in IoT are presented to enhance the understanding of the state of the art IoT development. To investigate the fog/edge computing-based IoT, this paper also investigate the relationship between IoT and fog/edge computing, and discuss issues in fog/edge computing-based IoT. Finally, several applications, including the smart grid, smart transportation, and smart cities, are presented to demonstrate how fog/edge computing-based IoT to be implemented in real-world applications.

A Survey on Internet of Things: Architecture, Enabling Technologies, Security and Privacy, and Applications

Course Description This is an advanced course in which we explore the field of Statistical Optics. Topics covered include such subjects as the statistical properties of natural (thermal) and laser light, spatial and temporal coherence, effects of partial coherence on optical imaging instruments, effects on imaging due to randomly inhomogeneous media, and a statistical treatment of the detection of light. Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.

http://ieeexplore.ieee.org/iel5/3/23094/01073023.pdf

Statistical optics

Metasurfaces: From microwaves to visible

Optical Waveguide Theory

This letter presents a new metamaterial-based waveguide technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and sub- millimeter waves. The latter is due to the fact that there are no mechanical joints across which electric currents must float. The gap waveguides have lower losses than microstrip lines, and they are completely shielded by metal so no additional packaging is needed, in contrast to the severe packaging problems associated with microstrip circuits. The gap waveguides are realized in a narrow gap between two parallel metal plates by using a texture or multilayer structure on one of the surfaces. The waves follow metal ridges in the textured surface. All wave propagation in other directions is prohibited (in cutoff) by realizing a high surface impedance (ideally a perfect magnetic conductor) in the textured surface at both sides of all ridges. Thereby, cavity resonances do not appear either within the band of operation. The present letter introduces the gap waveguide and presents some initial simulated results.

Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates

A novel formulation for the surface impedance characterization is introduced for the canonical problem of surface fields on a perfect electric conductor (PEC) circular cylinder with a dielectric coating due to a electric current source using the Uniform Theory of Diffraction (UTD) with an Impedance Boundary Condition (IBC). The approach is based on a TE/TM assumption of the surface fields from the original problem. Where this surface impedance fails, an optimization is performed to minimize the error in the SD Green's function between the original problem and the equivalent one with the IBC. This asymptotic method, accurate for large separations between source and observer points, in combination with spectral domain (SD) Green's functions for multidielectric coatings leads to a new hybrid SD-UTD with IBC to calculate mutual coupling among microstrip patches on a multilayer dielectric-coated PEC circular cylinder. Results are compared with the eigenfunction solution in SD, where a very good agreement is met.

/pdf/surface-impedance-characterization-for-mutual-coupling-5goui28bui.pdf

Surface impedance characterization for mutual coupling calculation of patches on a dielectric-coated PEC circular cylinder

: The realization of structures that do not scatter electromagnetic field, i.e. structures that appear invisible for EM waves is not a new concept. The possibility of a plane wave passing through some structure without distortions (i.e. with zero scattered field) has been investigated theoretically since 1960s (see e.g. [1]-[4]). Recently, the possibility of cloaking objects using a metamaterial cover has extensively been studied ([5]-[7]). In this approach, material has been used to render a volume effectively invisible to incident radiation, i.e. to squeeze space from a volume into a shell surrounding the concealment volume. Coordinate transformations that are used for cloak design do not influence the form of Maxwell s equations, but they affect permittivity and permeability tensors (&#949; and &#956; respectively), making the needed materials spatially varying and anisotropic. When viewed externally, the concealed volume and the cloak both appear to have the propagation properties of free space, i.e. they appear invisible to electromagnetic waves. The required anisotropy is supposed to be obtained by using metamaterials. The main realized outcomes of the project is the development of the program UniaxCloak that analyzes cylindrical and spherical cloaks made from the uniaxial materials. The program can fully characterize uniaxial cloaks, i.e. it calculates scattered width and total scattered width in a frequency range of interest. In the cylindrical case, the incident wave can have arbitrary angle of incidence. And we have made a detailed investigation of properties of cloaks that are made from uniaxial materials. In practice, such cloaks can be made from metamaterials, for example from split-ring periodic structures or periodic wire structures.

http://www.dtic.mil/dtic/tr/fulltext/u2/a555070.pdf

Metamaterial-Based Cylinders Used for Invisible Cloak Realization

The purpose of this paper is to study realization feasibility of the cloak structures where the continuously-varying structure is realized as multilayer structure with the stepwise approximation of the constitutive parameters. In order to do that, the influence of the number of cloak layers is investigated, and it is shown that with only three layers it is possible to obtain a better cloak performance than the Schurig cloak (containing ten layers), and that with ten or more layers one can design a cloak that is practically invisible. These results are obtained by merging the program for analyzing uniaxial cylindrical structures with the global optimization program based on the particle swarm optimization algorithm.

Feasibility study of uniaxial structures used for invisible cloak design

Recently the so-called DB boundary conditions were introduced that exhibit characteristics similar to that of an isotropic soft surface, except for an anomaly at normal incidence. This anomaly has also been amended, and the amended DB boundary condition has been shown to represent reflection from an EBG surface within the bandgap. The present paper summarizes the calculated characteristics of a practical planar EBG surface when modelled both with CST and the homogenous PMC-amended DB boundary condition. The paper also shows that the surface of an anistrotropic material with zero eps_z and mu_z will behave similar to the original DB boundary condition, and this is used to understand the anomaly for normal incidence by studying the case of eps_z and mu_z approaching zero.

https://publications.lib.chalmers.se/records/fulltext/143602/local_143602.pdf

Modelling EBG surfaces using amended DB boundary conditions

A general hybrid approach for the analysis of different curved antenna arrays or reflecting/transmitting surfaces is presented. The basis of the approach is a rigorous spectral domain approach and a method of moments which are combined with an appropriate asymptotic method in order to accelerate the analysis and expand its possibilities. Merging of the two methods is achieved by applying asymptotic extraction in the calculation of the reaction integrals of the method of moments matrix. This allows for the good properties of individual methods such as the accuracy of the spectral domain method and the speed of the asymptotic method to be for the most part preserved in the resulting method. The possibilities of this approach are demonstrated on two examples which show excellent results.

http://ieeexplore.ieee.org/iel5/4658782/4747505/04747578.pdf

Zvonimir Sipus

Papers

Surface impedance characterization for mutual coupling calculation of patches on a dielectric-coated PEC circular cylinder

Metamaterial-Based Cylinders Used for Invisible Cloak Realization

Feasibility study of uniaxial structures used for invisible cloak design

Modelling EBG surfaces using amended DB boundary conditions

Hybrid method for the analysis of curved electromagnetic structures