Motion Responses of a Berthed Tank under Resonance Coupling Effect of Internal Sloshing and Gap Flow

The growth of global energy transportation has promoted the rapid increase of large-scale LNG (liquefied natural gas) carriers, and concerns around the safety of LNG ships has attracted significant attention. Such a floating structure is affected by the external wave excitation and internal liquid sloshing. The interaction between the structure’s motion and the internal sloshing under wave actions may lead to the ship experiencing an unexpected accident. In this research, a hydrodynamic experiment is conducted to investigate the motion responses of a floating tank mooring, both close to and away from a dock. The resonance coupling effect of the internal sloshing and gap flow on the tank’s motion is considered. Based on the measured motion trajectory of the floating tank, the stability and safety of the floating tank are estimated. The results show that the sloshing resonance and narrow gap resonance are beneficial to the stability of the ship. This is helpful for controlling the motion of a berthed ship under wave action with a reasonable selection of the gap distance and the liquid level.

Failure of the tail rotor of the Mi-24 helicopter as a result of a long-term impact of spatial resonance coupling

The most important element that has an impact on the safety of flight includes the helicopter power plant and the transmission shaft assembly. Monitoring with the use of the traditional vibroacoustic techniques does not provide satisfactory results. It is especially difficult to detect spatial resonance couplings, which may result in dangerous and rapid breaking of elements. This article focuses on a specific mechanism for formation and deepening of resonance and effects of resonance couplings of two subassemblies. For their monitoring, the FAM-C method was applied. It uses an on-board generator as a sensor. This is a synchronous method, which enables one to detect the onset of spatial resonance.

Lossy mode resonances in photonic crystal fibers

The interaction effect of the fundamental mode in a special photonic crystal fiber (PCF) with a thin-film absorbing coating deposited on a surface of a fiber cladding on the optical transmission of the PCF is theoretically studied. It is shown that the transmission has a multi-peak spectrum that is determined by the resonance capture of the fundamental PCF mode energy by the coating. In some cases, this capture is explained by a resonance coupling between the fundamental core mode and leaky modes of the coating, or between the fundamental PCF mode and cladding modes located between PCF air channels and the coating. Examples are presented of using this effect to develop fiber-optic sensors of refractive index or pressure, and to sense a nanoscale adsorption layer of ammonia molecules deposited on a coating surface contacting air.

Novel Electrical Modeling, Design and Comparative Control Techniques for Wireless Electric Vehicle Battery Charging

Dynamic wireless power systems are an effective way to supply electric vehicles (EVs) with the required power while moving and to overcome the problems of low mileage and extensive charging times. This paper targets modeling and control for future dynamic wireless charging using magnetic resonance coupling because of the latter’s efficiency. We present a 3D model of transmitter and receiver coils for EV charging with magnetic resonance wireless power developed using ANSYS Maxwell. This model was incorporated into the physical design of the magnetic resonance coupling using ANSYS Simplorer in order to optimize the power. The estimated efficiency was around 92.1%. The transient analysis of the proposed circuit was investigated. A closed-loop three-level cascaded PI controller- was utilized for wireless charging of an EV battery. The controller was designed to eliminate the voltage variation resulting from the variation in the space existing between coils. A single-level PI controller was used to benchmark the proposed system’s performance. Furthermore, solar-powered wireless power transfer with a maximum power point tracker was used to simulate the wireless charging of an electric vehicle. The simulation results indicated that the EV battery could be charged with a regulated power of 12 V and 5 A through wireless power transfer. Fuzzy logic and neuro-fuzzy controllers were employed for more robustness in the performance of the output. The neuro-fuzzy controller showed the best performance in comparison with the other designs. All the proposed systems were checked and validated using the OPAL Real-Time simulator. The stability analysis of the DC–DC converter inside the closed-loop system was investigated.

Efficient Wireless Power Transfer via Magnetic Resonance Coupling Using Automated Impedance Matching Circuit

In this paper, an automated impedance matching circuit is proposed to match the impedance of the transmit and receive resonators for optimum wireless power transfer (WPT). This is achieved using a 2D open-circuited spiral antenna with magnetic resonance coupling in the low-frequency ISM band at 13.56 MHz. The proposed WPT can be adopted for a wide range of commercial applications, from electric vehicles to consumer electronics, such as tablets and smartphones. The results confirm a power transfer efficiency between the transmit and receive resonant circuits of 92%, with this efficiency being sensitive to the degree of coupling between the coupled pair of resonators.

Demonstration of toroidal metasurfaces through near-field coupling of bright mode resonators

Bright mode resonances are not well-acknowledged for inducing mode hybridizations. However, we demonstrate multiple bright resonators coupled through electromagnetic fields can induce resonance mode hybridizations. Although one of the hybridized modes shows parallel magnetic moments but the other mode demonstrates anti-parallel magnetic moments leading to magnetic toroidal resonances. Normally excitation of toroidal modes demands complex structures and/or bright-dark mode interactions. However, in this work, we employ solely bright resonators to excite toroidal modes. Unlike bright-dark mode coupling, exclusive bright mode resonance coupling enables larger free space energy merging into the metasystem leading to stronger energy confinement in the metasurface array.

Wireless power transfer system based on frequency and impedance matching hybrid adjustment against system detuning

System detuning caused by a variation in the distance between the transmitting and receiving terminals can greatly reduce the transmission power and efficiency of a magnetic resonance-coupled wireless power transmission (WPT) system, which limits the WPT application scope. This paper proposes a magnetic resonance coupling wireless power transmission system, which is based on jointly and continuously adjustable frequency compensation (CAFC) and two-transistor-controlled variable capacitor circuits (TCVCs). Therefore, this system can reach the resonant state by using CAFC and two-TCVCs when the transmission distance is changed. The proposed system can adaptively adjust combinations of the operating frequency and equivalent compensation capacitor’s capacitance to achieve impedance matching avoiding the phase difference caused by the imaginary part of the impedance, thus maintaining stable transmission efficiency under the condition of transmission distance variation. Compared to the traditional magnetic coupled resonant circuit based on impedance matching or variable resonant frequency, the proposed system achieves higher efficiency and stability and dynamic distance adaptation.

Design of Powering Wireless Medical Sensor Based on Spiral-Spider Coils

Biomedical sensors help patients monitor their health conditions and receive assistance anywhere and at any time. However, the limited battery capacity of medical devices limits their functionality. One advantageous method to tackle this limited-capacity issue is to employ the wireless power transfer (WPT) technique. In this paper, a WPT technique using a magnetic resonance coupling (MRC-WPT)-based wireless heart rate (WHR) monitoring system—which continuously records the heart rate of patients—has been designed, and its efficiency is confirmed through real-time implementation. The MRC-WPT involves three main units: the transmitter, receiver, and observing units. In this research, a new design of spiral-spider coil was designed and implemented for transmitter and receiver units, respectively, to supply the measurement unit, which includes a heart rate sensor, microcontroller, and wireless protocol (nRF24L01) with the operating voltage. The experimental results found that an adequate voltage of 5 V was achieved by the power component to operate the measurement unit at a 20 cm air gap between the receiver and transmitter coils. Further, the measurement accuracy of the WHR was 99.65% comparative to the benchmark (BM) instrument. Moreover, the measurements of the WHR were validated based on statistical analyses. The results of this study are superior to those of leading works in terms of measurement accuracy, power transfer, and Transfer efficiency.

An Enhanced Method of Contactless Charging of Railway Signaling Torch Light

Wireless charging, also known as contactless charging (for shorter range), is a method of supplying energy to electrical devices by sending electricity via an air gap. Wireless charging methods have advanced recently, and commercial solutions have been developed, providing a potential option to overcome the energy bottleneck of typically portable battery-powered gadgets. Due to its simplicity and improved user experience, this technology is attracting a wide range of applications, from low-power gadgets to high-power electric cars. However, including wireless charging into the systems raises a number of difficult challenges in terms of implementation, scheduling, and power management. One such application is to convert the existing system of traditional battery powered railway signaling torchlight into a rechargeable type contactless charging system. This provides a better way of increasing the life time of the product and has better compactness. A rechargeable Li-ion battery must be installed in lieu of the old non-rechargeable battery. To achieve satisfactory efficiency, the magnetic resonance coupling technology of contactless charging can be utilized. Through a shorter air gap, electrical power is transmitted from the charging module (main coil) to the Torchlight (secondary coil). Overall, the present system's cost, size are reduced and lifetime is increased.