This study proposes a low-frequency metamaterial(MM) coupled with an equivalent circuit model to ... more This study proposes a low-frequency metamaterial(MM) coupled with an equivalent circuit model to emulate the behavior of an MM-based Wireless Power Transfer (WPT) system. For this purpose, the electromagnetic simulation and Finite Element Analysis (FEA) of the proposed MM-based WPT system are performed in ANSYS three-dimensional (3D) High-Frequency Structured Simulator (HFSS). In addition, numerical analysis of the circuit design of the proposed structure is performed in a MATLAB simulation environment to evaluate its transfer characteristics. While some methods, including effective medium theory and transmission line circuit model, have been exploited to explain the physical mechanism of MM-based WPT systems, some of the reactive parameters and the fundamental physical interpretation have not been clearly expounded. In contrast to existing theoretical models, the proposed approach focuses on the effect of system parameters of the MM and transfer coils on transfer characteristics, coupled with its effectiveness in analyzing complex circuits. A design prototype is fabricated for experimental measurement of power transfer efficiency and medium parameters using the KeySight ENA 5061 vector network analyzer (VNA), confirming the validity of the proposed design. The excellent efficiency enhancement and mutual coupling make the design an attractive solution for WPT applications. A close agreement of the experimental results and numerical simulation validates the accuracy of the analytical model.
With increasing penetration of wireless charging technologies comes an ever-rising demand for wir... more With increasing penetration of wireless charging technologies comes an ever-rising demand for wireless power transfer (WPT) structures that demonstrate high power transfer and power transfer efficiency (PTE), especially over wide transfer distance. The concern with reliability in adopting wireless charging technologies in consumer and industrial applications (including mobile chargers and dynamic wireless charging of electric vehicles, EVs) stems from fluctuating output power and low power transfer efficiency (PTE). Moreover, the inherently high resonant frequency of existing metamaterial (MM)based WPT designs imposes a high switching stress on power semiconductors and passive components, resulting in high power dissipation, especially in high power applications. This manuscript presents a critical survey of recent studies and developments in MM-based WPT systems. First, the fundamental concepts and classification of WPT technologies based on magnetic resonant coupling (MRC), inductive coupling etc. are discussed. Going forward, key MM design considerations, including resonance operating frequencies, effective permittivity (ϵ r ), effective permeability (µ r ), numerical modeling, equivalent circuit representations, and 3D fabrication technologies are widely analyzed and critiqued. Additionally, the performance enhancing effect of integrating different MM designs with existing WPT systems are explicitly discussed. Finally, the technical challenges associated with the resonant operating frequencies of MM, miniaturization of MM design footprint, and 3D prototyping are investigated while also presenting potential solutions.
The present conflict in Ukraine is considered one of the most significant crises in Europe since ... more The present conflict in Ukraine is considered one of the most significant crises in Europe since the disintegration of Yugoslavia. Moreover, it is taking place in a very specific area with special interests of external actors. The conflict, which has escalated into a war, has been regulated and, in fact, frozen, due to the participation of international organisations. This study focuses on the role of three European security organisations-the European Union (eu), the North Atlantic Treaty Organization (nato) and the Organization for Security and Cooperation in Europe (osce)-in the de-escalation and resolution of the conflict in Ukraine. The qualitative case study examines the ability of the selected organisations to take a position and enter the conflict. The study proves that the ability of an organisation to enter the conflict is, to a certain extent, determined by its position towards the conflict (resulting particularly from its membership) and by the tools available to it.
This study proposes a low-frequency metamaterial(MM) coupled with an equivalent circuit model to ... more This study proposes a low-frequency metamaterial(MM) coupled with an equivalent circuit model to emulate the behavior of an MM-based Wireless Power Transfer (WPT) system. For this purpose, the electromagnetic simulation and Finite Element Analysis (FEA) of the proposed MM-based WPT system are performed in ANSYS three-dimensional (3D) High-Frequency Structured Simulator (HFSS). In addition, numerical analysis of the circuit design of the proposed structure is performed in a MATLAB simulation environment to evaluate its transfer characteristics. While some methods, including effective medium theory and transmission line circuit model, have been exploited to explain the physical mechanism of MM-based WPT systems, some of the reactive parameters and the fundamental physical interpretation have not been clearly expounded. In contrast to existing theoretical models, the proposed approach focuses on the effect of system parameters of the MM and transfer coils on transfer characteristics, coupled with its effectiveness in analyzing complex circuits. A design prototype is fabricated for experimental measurement of power transfer efficiency and medium parameters using the KeySight ENA 5061 vector network analyzer (VNA), confirming the validity of the proposed design. The excellent efficiency enhancement and mutual coupling make the design an attractive solution for WPT applications. A close agreement of the experimental results and numerical simulation validates the accuracy of the analytical model.
With increasing penetration of wireless charging technologies comes an ever-rising demand for wir... more With increasing penetration of wireless charging technologies comes an ever-rising demand for wireless power transfer (WPT) structures that demonstrate high power transfer and power transfer efficiency (PTE), especially over wide transfer distance. The concern with reliability in adopting wireless charging technologies in consumer and industrial applications (including mobile chargers and dynamic wireless charging of electric vehicles, EVs) stems from fluctuating output power and low power transfer efficiency (PTE). Moreover, the inherently high resonant frequency of existing metamaterial (MM)based WPT designs imposes a high switching stress on power semiconductors and passive components, resulting in high power dissipation, especially in high power applications. This manuscript presents a critical survey of recent studies and developments in MM-based WPT systems. First, the fundamental concepts and classification of WPT technologies based on magnetic resonant coupling (MRC), inductive coupling etc. are discussed. Going forward, key MM design considerations, including resonance operating frequencies, effective permittivity (ϵ r ), effective permeability (µ r ), numerical modeling, equivalent circuit representations, and 3D fabrication technologies are widely analyzed and critiqued. Additionally, the performance enhancing effect of integrating different MM designs with existing WPT systems are explicitly discussed. Finally, the technical challenges associated with the resonant operating frequencies of MM, miniaturization of MM design footprint, and 3D prototyping are investigated while also presenting potential solutions.
The present conflict in Ukraine is considered one of the most significant crises in Europe since ... more The present conflict in Ukraine is considered one of the most significant crises in Europe since the disintegration of Yugoslavia. Moreover, it is taking place in a very specific area with special interests of external actors. The conflict, which has escalated into a war, has been regulated and, in fact, frozen, due to the participation of international organisations. This study focuses on the role of three European security organisations-the European Union (eu), the North Atlantic Treaty Organization (nato) and the Organization for Security and Cooperation in Europe (osce)-in the de-escalation and resolution of the conflict in Ukraine. The qualitative case study examines the ability of the selected organisations to take a position and enter the conflict. The study proves that the ability of an organisation to enter the conflict is, to a certain extent, determined by its position towards the conflict (resulting particularly from its membership) and by the tools available to it.
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Papers by Mary Sanyaolu