High frequency isolated AC/AC converter and soft switching control strategy

The fast time-varying channels in high-speed scenarios impact signal transmission between transceivers and pose challenges to both the accuracy and bandwidth utilization of communication systems. Semantic communication, known for its ability to significantly reduce transmission bandwidth and enhance communication reliability, is especially effective in extreme environments. However, current semantic communication systems lack a comprehensive physical layer design, which limits their ability to achieve optimal performance in rapidly changing conditions. In this paper, we propose an adaptive semantic speech recognition and cloning transmission system with a superimposed pilot (SwitchAC-SIP) tailored for high-speed scenarios to ensure high-quality speech transmission. The system converts speech signals into textual content and speaker timbre features at the transmitter, while a speech cloning model reconstructs the speech at the receiver with a timbre closely resembling the original speaker based on these features, thereby eliminating the need to retrain the speech generation model for different users, ensuring both transmission quality and efficiency. To address the impact of high-speed environments on channel estimation performance, we introduce a superimposed pilot (SIP) in the physical layer. This method superimposes pilots and data across the entire time-frequency grid with a specific power ratio, significantly mitigating the detrimental effects of high-speed conditions on semantic communication systems. Furthermore, to enhance system flexibility in dynamic scenarios, we design a channel-adaptive network that dynamically allocates bandwidth ratios for text and audio semantics based on real-time channel conditions. This adaptive approach prioritizes the protection of critical semantic features according to user requirements. Simulation results demonstrate the substantial improvements in transmission efficiency and accuracy achieved by the proposed system.

Long-distance wireless energy transmission is realized by photoelectric conversion through lasers and photovoltaic cells. However, existing devices have low transmission power and low transmission efficiency. Exploring the main factors that limit the transmission efficiency during transmission is necessary to improve the transmission power and efficiency, and theoretically analyze these factors that affect transmission efficiency, such as beam quality, divergence angle, wavelength and so on. This will provide research directions for subsequent work. A multiwavelength laser wireless energy transmission experimental platform was built by using powersphere, laser with three different wavelengths and other devices. This platform was used for transmission efficiency verification experiment. The total electro-optical-electric conversion efficiency values obtained by the 532, 1030, and 808 nm lasers are 0.01%, 0.08%, and 0.11%, respectively. The corresponding laser-to-electric conversion efficiency values are 1.37%, 1.60%, and 0.73%, respectively. Experimental results show that the electro-optic conversion efficiency of the laser and the photoelectric conversion efficiency of the photovoltaic receiver is the main reasons for the low conversion efficiency of the system. In addition, factors such as the expansion ratio of the beam expander, laser collimation, laser uniformity at the photovoltaic receiver end, and circuit structure, affect the conversion efficiency of the system.

We proposed a technique to improve the transmission efficiency by handling the impedance inside the cavity by utilizing a monopole probe (matching probe) terminated by a variable reactance circuit. As a result of measurement, the reflection coefficient of the transmitter side reduced from 0.895 to 0.324 before and after inserting the matching probe. The reflection coefficient of the receiver side reduced from 0.967 to 0.882. The transmission efficiency improved from 0.67 % to 13.09 %. From the above, it was confirmed that transmission efficiency is improved by handling cavity impedance.

This paper presents the design and analysis of a modified double-ended forward converter (DEFC) for stepper motor-based robotic applications. The proposed converter topology provides galvanic isolation between the input and output while also higher efficiency with a smooth operative system, making it suitable for use in robotic systems that require both power and control signals to be transmitted. The paper also discusses the control strategy for the converter, which uses Proportional Integral (PI) to regulate the output voltage and current. The control strategy is implemented using a microcontroller-based system, which provides precise control of the output parameters. The converter is tested using a stepper motor-based load, and the results demonstrate the effectiveness of the proposed topology and control strategy. In addition to the experimental results, the paper also presents a detailed analysis of the converter’s performance. The analysis includes the input voltage and current, capacitor voltage, MOSFET parameters, output voltage and current, and calculation of efficiency. The analysis results show that the proposed converter topology and control strategy offer high efficiency comparing to existing converting approaches. Overall, the proposed double-ended forward converter offers a suitable solution for stepper motor-based robotic applications, providing efficient and reliable power and control signals. The results demonstrate the effectiveness of the proposed converter topology and control strategy, making it a promising option for use in future robotic systems.

In order to reduce the difficulty of the tuning work and improve transmission efficiency at the 320-kV heavy ion multidisciplinary research facility (IMRF), an online optimization system was developed. In this paper, the difficulties of manual tuning are analyzed amply. Various optimization-based approaches were considered and a Bayesian optimization method was selected and implemented in hardware. We have applied the online optimization system at the beamline to increase transmission efficiency. The transmission efficiency obtained by this online tuning system can reach 50%, which is better than the manual tuning 30% to 35%. The general work developed in this paper can provide a reference for the design and implementation of online tuning approaches for various complex systems, not just accelerator facilities.

Quantum Key Distribution (QKD) is increasingly pivotal in securing communication channels against the looming threats posed by quantum computing. However, existing QKD protocols encounter challenges related to efficiency and transmission capabilities. In response, this research investigates the integration of metamaterials into QKD systems, aiming to fortify security and enhance practicality. In the current landscape of quantum communication, where the vulnerability of classical encryption methods is magnified by rapid advancements in quantum computing, finding innovative solutions is imperative. This study is motivated by the need to strengthen the security and viability of QKD protocols to meet the demands of evolving cryptographic threats. By integrating metamaterials, the authors optimise quantum state control, improve signal‐to‐noise ratio (SNR), and enable longer transmission distances. Through mathematical modelling and simulations, the authors demonstrate how metamaterials reduce errors and enhance the robustness of QKD systems. Our findings show significant improvements in transmission efficiency and security, making Metamaterial‐Based Quantum Key Distribution (MQKD) a promising approach for future quantum communication networks. The study not only advances the understanding of the theoretical foundations, but also presents simulated results illustrating the practical effectiveness of MQKD. The exploration of these innovative techniques contributes to the ongoing efforts to secure quantum communication channels.

The authors discussed a variable bit rate voice coding system in digital communications networks. A novel voice compression method which provides significant improvement in transmission efficiency and flexibility for communications systems is described. The basic scheme used for the investigations involves the use of split vector quantized (SVQ) transform coding (TC) in conjunction with pitch prediction (PP) to achieve excellent voice quality at rates of 4.8 kb/s and below. The authors describe of the algorithm and its implementation for a variable bit rate voice coding system from 4.8 kb/s to 2.4 kb/s. >

In the field of wireless power transfer technologies, the improvement of transmission efficiency is one of the critical issues. It is important to understand how much power loss is imposed in which areas of a wireless power transfer system in the development phase. Since the transmission characteristics change according to ambient conditions, a measuring instrument capable of observing electric power during power transfer is required. We, Daihen Corporation, have developed a real-time power and impedance sensor useful as a data collection tool in order to improve power transmission efficiency. We have verified, using this sensor, the feasibility of the above objective by optimizing the circuit constants based on measured values obtained during practical power transfer.

<sec>Magnetic resonance wireless power transfer (WPT) has gradually become a popular research topic of near-field regulation in recent years, with wide applications in the fields of mobile phones, implantable medical devices, electric vehicles, and many other fields. However, several challenges remain to be addressed: near-field coupling, which induces multiple frequency splits and prevents the system from maintaining a fixed operating frequency; coupled arrays, which are susceptible to structural errors and parameter perturbations; current research, which primarily focuses on single-load transmission and has resulted in undeveloped multi-load transmission systems; the direction of transmission, which is difficult to control flexibly. In recent years, photonic artificial microstructures have provided a flexible platform for studying topological physics, arousing significant research interest in their fundamental topological characteristics. The most prominent features of topological structures are their nonzero topological invariant and the robust edge states determined by the bulk-edge correspondence: these features can overcome disturbances caused by defects and disorders. Moreover, by modulating the wave function distribution of topological states, energy can be precisely localized, enabling directional WPT. Therefore, implementing topological modes in WPT systems are of significant scientific importance.</sec><sec>This review summarizes recent researches on topological models for robust WPT, which are divided into three main parts. The first part introduces one-dimensional periodic topological structures, focusing primarily on the significant improvements in transmission efficiency and robustness achieved by utilizing topological edge states in the Su-Schrieffer-Heeger (SSH) model for WPT. Moreover, a composite chain formed by two SSH chains is constructed to realize a higher-order parity-time (PT) symmetric topological model. This approach solves the frequency splitting caused by coupled edge states and exhibits lower power losses in standby mode. The second part discusses several types of aperiodic one-dimensional topological chains. By introducing topological defect states at the interface between two different dimer chains, robust multi-load WPT is achieved. Furthermore, based on the integration of artificial intelligence algorithms, the SSH-like topological model enables more efficient and robust WPT than traditional SSH model. The asymmetric edge states in quasi-periodic Harper chain provide a solution for directional transmission in WPT applications. By introducing nonlinear circuits, this model enables active control of the transfer direction. The third part presents the application of high-order topological corner states in multi-load robust WPT, demonstrating the selective excitation of both symmetric and asymmetric corner modes.</sec><sec>Finally, the application prospects of topological modes in WPT systems are discussed. With the development of new physics, the integration of non-Hermitian physics and topological physics holds great promise for achieving simultaneous energy-information transfer, and is expected to achieve compatible WPT, wireless communication, and wireless sensing within a single system. Such a fusion technology will provide breakthroughs in efficiency, robustness, and multifunctionality for next-generation wireless systems.</sec>

Effect of receptor binding domain mutations on receptor binding and transmissibility of avian influenza H5N1 viruses

Planetary gear transmission mechanisms (PGTMs) are widely used in mechanical transmission systems due to their compact structure and high transmission efficiency. To implement the reliability design and optimization of a PGTM, a novel multi-objective dynamic reliability optimization approach is proposed. First, a multi-objective reliability optimization model is established. Furthermore, considering the strength degradation of gears during service, a dynamic reliability analysis is conducted based on the theory of nonlinear fatigue damage accumulation. In addition, to improve computing efficiency, a random forest surrogate model based on the particle swarm optimization algorithm is proposed. Finally, an adaptive multi-objective evolutionary algorithm based on decomposition (AMOEA/D) is designed to optimize the mechanism, along with an adaptive neighborhood updating strategy and a hybrid crossover operator. The feasibility and superiority of the proposed approach are verified through an NGW planetary gear reducer. The results show that the proposed surrogate model can reduce the calculation cost and has high accuracy. The AMOEA/D algorithm can improve transmission efficiency, reduce gear volume and ensure reliability at the same time. It can provide guidance for actual gear production.

CC-OLIA: A Dynamic Congestion Control Algorithm for Multipath QUIC in Mobile Networks

In RISC-V processor design, the Store-Forward processing architecture is used to coordinate data storage and loading operations to avoid collisions. However, as the demand for multi-core and parallel tasks increases, traditional methods face high transmission latency and low bandwidth utilization problems, affecting the overall system performance. Therefore, we propose a multi-channel priority scheduling mechanism, which dynamically adjusts the priorities of multiple data streams to optimize resource allocation, reduce congestion, and improve transmission efficiency. A RISC-V test platform is built based on the Gem5 simulator, and the performance of standard scheduling and multi-channel priority scheduling under data-intensive workloads is compared. The experimental results show that after adopting the new mechanism, the average transmission delay is reduced from 60 nanoseconds to 48 nanoseconds, which is a reduction of 20%. At the same time, the peak throughput increased from 5GB per second to 6.5 GB, an increase of 30%. In 1000 random data transmission tasks, the scheduling mechanism reduces the processing completion time to 80 milliseconds, which reduces the waiting time by 20% compared to the benchmark of 100 milliseconds. These data indicate that the mechanism effectively mitigates the congestion problem and optimizes resource utilization. Through multi-channel priority scheduling, the transmission efficiency of the Store-Forward processing structure is significantly improved in the RISC-V environment, providing a feasible solution for high-performance computing applications.

This paper introduces the control strategy of energy storage converter in different operation modes of micro-grid system. Firstly, the energy storage converter is modeled, studied in parallel mode energy storage battery charging and discharging control strategy in dc side and ac PQ control strategy, the V/f control of energy storage converter under off-grid condition is controlled, and the overall control scheme of energy storage converter is given. Secondly, this paper presents a solution to the impact of energy storage converter in switching between different working modes. Finally, based on the Matlab/Simulink simulation model, the semi-physical real-time simulation platform based on APPSIM software has further verified the control strategy proposed in this paper.

This paper reports a new dynamic modeling method for switched reluctance motor (SRM) which can account for neighboring phase coupling effects. The dynamic model is developed using a few sets of finite element method (FEM)-computed phase flux linkage/current/position data under the condition of simultaneous excitation of two neighboring phases. The combination of piecewise Hermite cubic spline and Fourier series techniques is used to represent each FEM-calculated flux linkage data set. The methods to implement and to verify the dynamic model using simulation techniques are presented. The model is ready to be incorporated with various converter topologies and control strategies. It can provide valuable information for motor design evaluation and its controller design evaluation. The modeling method has been implemented using Saber circuit simulator for a 4-phase SRM driven by a split DC-link inverter. Dynamic simulation results have been obtained for two different SRM winding configurations. The significance of its neighboring phase coupling effects is evaluated by comparing the simulation results of a model including the effects with the simulation results of a degraded model neglecting the effects.