Orbital Angular Momentum Waves: Generation, Detection and Emerging Applications

Orbital angular momentum (OAM) has aroused a widespread interest in many fields, especially in telecommunications due to its potential for unleashing new capacity in the severely congested spectrum of commercial communication systems. Beams carrying OAM have a helical phase front and a field strength with a singularity along the axial center, which can be used for information transmission, imaging and particle manipulation. The number of orthogonal OAM modes in a single beam is theoretically infinite and each mode is an element of a complete orthogonal basis that can be employed for multiplexing different signals, thus greatly improving the spectrum efficiency. In this paper, we comprehensively summarize and compare the methods for generation and detection of optical OAM, radio OAM and acoustic OAM. Then, we represent the applications and technical challenges of OAM in communications, including free-space optical communications, optical fiber communications, radio communications and acoustic communications. To complete our survey, we also discuss the state of art of particle manipulation and target imaging with OAM beams

Thermal Modeling and Analysis of Roadway Embedded Wireless Power Transfer Modules

Wireless charging of electric vehicles is a developing technology which potentially increases efficiency and safety. It also allows for charging vehicles while they are moving by having charging stations embedded in the roadway. Because roadways are thermally insulating, it is important to know how the heat from the charging stations will move through the roadway, which will allow further research into whether the heat will cause damage to the components in the station or to the roadway. This thesis studies the way the heat moves through concrete with wireless charging coils embedded in it. This is accomplished by measuring the relevant material properties of materials used in such a system of concrete and charging components and using those properties in a simulation. Specifically, to measure the properties of concrete, an experiment with a matching computer simulation is used. These measured properties and others are then used in a different computer simulation to explore how quickly a charging station will heat up. This simulation is compared to experiments on a real charging station for validation. A station with a material designed to absorb heat implemented is also compared to a station without such a material in an effort to understand other ways of managing the heat generation within the station

Accelerating the simulation of wireless cellular systems

The simulation of comprehensive models for cellular wireless systems poses a computational burden of great proportions. When a sub-model for transmitter power level control is included in the simulation, a continuous process in discrete-time is introduced, requiring traditional execution to advance in small, regular time-steps. to accelerate these simulations, we propose the use of interval jumping, a novel technique which allows time to progress in adaptive, irregularly-sized jumps in time. The foundations for this mechanism are laid out in the light of the simulation of a complex simulation model which includes teletraffic, radio propagation, channel allocation, transmitter power control, and user mobility. We demonstrate the performance of this method through the use of sequential and parallel simulation.;Approaching the problem of accelerating the simulation of wireless systems from a different angle, we also identify a second important performance bottleneck. Calculations for interference computation, which may be carried out hundreds of times for each second of simulated time, require the evaluation of O(N2) interactions, for a system with N transmitter/receiver pairs. In order to provide a computationally cheaper and more scalable alternative to these operations, we study the applicability of an N-body algorithm, which brings time complexity down to O(N log N)

Distributed Hybrid Simulation of the Internet of Things and Smart Territories

This paper deals with the use of hybrid simulation to build and compose heterogeneous simulation scenarios that can be proficiently exploited to model and represent the Internet of Things (IoT). Hybrid simulation is a methodology that combines multiple modalities of modeling/simulation. Complex scenarios are decomposed into simpler ones, each one being simulated through a specific simulation strategy. All these simulation building blocks are then synchronized and coordinated. This simulation methodology is an ideal one to represent IoT setups, which are usually very demanding, due to the heterogeneity of possible scenarios arising from the massive deployment of an enormous amount of sensors and devices. We present a use case concerned with the distributed simulation of smart territories, a novel view of decentralized geographical spaces that, thanks to the use of IoT, builds ICT services to manage resources in a way that is sustainable and not harmful to the environment. Three different simulation models are combined together, namely, an adaptive agent-based parallel and distributed simulator, an OMNeT++ based discrete event simulator and a script-language simulator based on MATLAB. Results from a performance analysis confirm the viability of using hybrid simulation to model complex IoT scenarios.Comment: arXiv admin note: substantial text overlap with arXiv:1605.0487

Development of a Novel Wireless Electric Power Transfer System for Space Applications

This paper will introduce a new implementation for wireless electric power transfer systems: space applications. Due to the risks that constitute the use of electrical connector for some space missions/applications, a simple wireless power system design approach will be evaluated as an alternative for the use of electrical connectors. This approach takes into consideration the overall system performance by designing the magnetic resonance elements and by verifying the overall system electrical behavior. System characterization is accomplished by executing circuit and analytical simulations using Matlab(TradeMark) and LTSpiceIV(TradeMark) software packages. The design methodology was validated by two different experiments: frequency consideration (design of three magnetic elements) and a small scale proof-ofconcept prototype. Experiment results shows successful wireless power transfer for all the cases studied. The proof-of-concept prototype provided approx.4 W of wireless power to the load (light bulb) at a separation of 3 cm from the source. In addition. a resonant circuit was designed and installed to the battery terminals of a handheld radio without batteries, making it tum on at a separation of approx.5 cm or less from the source. It was also demonstrated by prototype experimentation that multiple loads can be powered wirelessly at the same time with a single electric power source

Development of multi-MHz Class-D soft-switching inverters

Wireless Power Transmission (WPT) systems are becoming rapidly mature and accessible to customers, and it is expected that they are going to take a large share of the electrical equipment market around the world in the near future. Many tech companies and university research labs have recently focused on design, development, and optimization of different blocks of these systems. WPT systems can be designed to transfer power either through electric fields or magnetic fields. Operating at the multi-MHz frequency will bring about the smaller size of the wireless link for both types of WPT systems. The advent of Wide Bandgap (WBG) devices like Gallium Nitride (GaN) FETs and Silicon Carbide (SiC) MOSFETs has paved the road to design multi-MHz inverters and use them as the Radio Frequency (RF) power source in the transmitter of WPT systems. Designing an efficient inverter which can maintain its soft-switching performance while facing variable load or delivering variable output power is one of the major design challenges in this field. The second challenge in this area is related to the difficulties of Electromagnetic Compatibility (EMC) of the inverter, which is the direct result of operating at MHz switching frequency range. The Electromagnetic Interference (EMI) level can be reduced by designing a stronger filter or trying to remove the harmonics from the switching source. In this thesis, to tackle the first challenge mentioned above regarding soft switching, the Dynamic Dead-Time Control (DDTC) approach is proposed and utilized to sustain the soft-switching of a multi-MHz Full-Bridge (FB) Class-D inverter over the full range of active load and output power. Simulation results are presented to show that dynamically controlling the Dead-Time (DT) during input DC voltage control and load variations, reduces switch-node voltage overshoot, prevents large current spikes in the switching devices, and reduces associated high switching loss. Finally, experimental results obtained from the prototype of the system are provided to validate the effectiveness of the proposed approach. Then, a soft-switching multi-MHz multi-level Class-D inverter is developed to address the second challenge of EMI issues associated with MHz switching frequency operation.The inverter is designed to eliminate the 3rd and 5th harmonics from its output voltage waveform. This will, in turn, make it possible to meet EMC and achieve the same level of harmonic attenuation on the output of the inverter with a smaller size and more efficient output EMI filter as opposed to utilizing a bulky, high-order, High-Quality (HQ) filter. The impact of DT on the modulation parameters of the multi-level inverter is investigated through mathematical analysis, and the results are utilized during the system simulations and practical implementation. A prototype is built to validate the theoretical and simulation analysis on a practical testbed. The harmonic analysis comparison carried out between the experimental results obtained from the multi-level inverter and FB Class-D inverter prototypes shows how the multi-level inverter is capable of suppressing unwanted 3rd and 5th harmonic to a much lower level which in turn leads to smaller size and more efficient output filter