Low Transmission Efficiency Research Articles

Epoxy-imine vitrimer having low dielectric constant and high wave transmission efficiency for mobile communication applications

The rapid growth of telecommunication technology calls for express evaluation and development for low dielectric constant (Dk) materials with higher performance requirements. At mean time, the extensive use of these dielectric materials generates increasing concerns over their crosslinking structures that cannot be readily recycled without causing environment pollution. Herein, a curing agent comprising dynamically exchangeable imine bonds was synthesized via the condensation of terephthalaldehyde (TPA) and isophorondiamine (IPDA). Epoxy vitrimers cured by this curing agent exhibited low Dk (2.75–2.79) and excellent wave transmission efficiency (>90.5 %) at high frequency range of 8.2–12.4 GHz. The cured resins can also be recycled through chemical degradation, producing reusable monomers. The cured resins demonstrate vitreous properties and its dielectric, thermal properties and wave transmission efficiency maintained unchanged after reprocessing. This work offers a strategy to prepare low Dk epoxy vitrimer used in communication field.

A Decoupled Modulation Strategy for Constant Voltage/Current Wireless Charging System Under High Coils Misalignment

ABSTRACTOutput fluctuation and lower transmission efficiency under load and mutual inductance variation are hot concerned in the wireless charging system for power batteries. In this paper, a decoupled tracking strategy is proposed to realize constant voltage (CV) or current (CC) output and high transmission efficiency. The circuit model of series–series compensation network is built, and corresponding transmission characteristics can be derived. First, the load and mutual inductance value can be estimated by measuring the primary electrical information, including the inverter output voltage, current, and the phase error between them. Then load‐independent voltage or current output characteristics under coils misalignment can be maintained by tracking the optimal switching frequency of inverter part. In addition, the value of output voltage or current can be adjusted flexibly for different operation occasions by the employment of pulse‐width modulation. As a result, the load‐independent output characteristics realization and output adjustment can be decoupled. Based on only the primary measuring information, the CV/CC output can be maintained via the proposed hybrid control strategy when the coils misalignment and load variation happen, increasing the robustness of whole wireless power transfer (WPT) system. Furthermore, the soft switching of all power switches in the inverter part can be realized to reduce the switching loss. Compared with previous research, the proposed wireless charging system has a higher power density and a simplified control strategy. Finally, an experimental platform with 60‐V charging voltage and 3.6‐A charging current is built to verify the feasibility of the proposed sys‐tem and control method.

Reconfigurable ultrasound focusing effect through acoustic barriers

The low transmission efficiency of ultrasonic waves in waveguides of a high acoustic impedance (referred to as dense materials), due to the impedance mismatch between the background media and the dense materials, poses a significant obstacle to practical applications of high-intensity focused ultrasound (HIFU) such as ultrasound therapy or medical imaging. To address this challenge, we present an inverse optimization scheme for fabrication of novel acoustic meta-lenses, enabling strengthened penetration and enhanced focusing of ultrasonic waves when the waves traverse barriers. Both simulation and experiment validate the effectiveness of the developed meta-lenses which are annexed to hemispherical plates, and demonstrate an enhanced transmission of the sound power by an order of magnitude compared to a scenario without the use of the meta-lens. The focal distance is reconfigurable by adjusting the geometric parameters of the meta-lenses. The proposed design philosophy is not restricted by the complexity of the target structures, and it allows the ultrasonic waves to pass through acoustic barriers with a non-uniform thickness yet maintaining efficient wave focusing. This study holds appealing applications in HIFU-enabled ultrasound imaging and therapy.

Terahertz spoof plasmonic neural network for diffractive information recognition and processing

All-optical diffractive neural networks, as analog artificial intelligence accelerators, leverage parallelism and analog computation for complex data processing. However, their low space transmission efficiency or large spatial dimensions hinder miniaturization and broader application. Here, we propose a terahertz spoof plasmonic neural network on a planar diffractive platform for direct multi-target recognition. Our approach employs a spoof surface plasmon polariton coupler array to construct a diffractive network layer, resulting in a compact, efficient, and easily integrable architecture. We designed three schemes: basis vector classification, multi-user recognition, and MNIST handwritten digit classification. Experimental results reveal that the terahertz spoof plasmonic neural network successfully classifies basis vectors, recognizes multi-user orientation information, and directly processes handwritten digits using a designed input framework comprising a metal grating array, transmitters, and receivers. This work broadens the application of terahertz plasmonic metamaterials, paving the way for terahertz on-chip integration, intelligent communication, and advanced computing systems.

A Stealthy Communication Model with Blockchain Smart Contract for Bidding Systems

With the widespread adoption of blockchain technology, its public ledger characteristic enhances transaction transparency but also amplifies the risk of privacy breaches. Attackers can infer users’ real identities and behaviors by analyzing public transaction patterns and address relationships, posing a severe threat to users’ privacy and security, and thus hindering further advancements in blockchain applications. To address this challenge, covert communication has emerged as an effective strategy for safeguarding the privacy of blockchain users and preventing information leakage. But existing blockchain-based covert communication schemes rely solely on the immutability of blockchain itself for robustness and suffer from low transmission efficiency. To tackle these issues, this paper proposes a stealthy communication model with blockchain smart contract for bidding systems. The model initiates by preprocessing sensitive information using a secret-sharing algorithm-the Shamir (t, n) threshold scheme-and subsequently embeds this information into bidding amounts, facilitating the covert transfer of sensitive data. We implemented and deployed this model on the Ethereum platform and conducted comprehensive performance evaluations. To assess the stealthiness of our approach, we employed a suite of statistical tests including the CDF, the Kolmogorov–Smirnov test, Welch’s t-test and K–L divergence. These analyses confirmed that amounts carrying concealed information were statistically indistinguishable from regular transactions, thus validating the effectiveness of our solution in maintaining the anonymity and confidentiality of information transmission within the blockchain ecosystem.

Intracellular magnesium optimizes transmission efficiency and plasticity of hippocampal synapses by reconfiguring their connectivity

AbstractSynapses at dendritic branches exhibit specific properties for information processing. However, how the synapses are orchestrated to dynamically modify their properties, thus optimizing information processing, remains elusive. Here, we observed at hippocampal dendritic branches diverse configurations of synaptic connectivity, two extremes of which are characterized by low transmission efficiency, high plasticity and coding capacity, or inversely. The former favors information encoding, pertinent to learning, while the latter prefers information storage, relevant to memory. Presynaptic intracellular Mg2+ crucially mediates the dynamic transition continuously between the two extreme configurations. Consequently, varying intracellular Mg2+ levels endow individual branches with diverse synaptic computations, thus modulating their ability to process information. Notably, elevating brain Mg2+ levels in aging animals restores synaptic configuration resembling that of young animals, coincident with improved learning and memory. These findings establish intracellular Mg2+ as a crucial factor reconfiguring synaptic connectivity at dendrites, thus optimizing their branch-specific properties in information processing.

Research on Three-Phase Wireless Power Transfer System

Aiming at the problems of low power, low energy transmission efficiency, and high stress in the circuit of a single-phase wireless power transfer system, this paper proposes a wireless power transfer (WPT) system with a three-phase angle difference of 120 degrees and establishes a COMSOL multi-physics simulation model for analysis. In this simulation model, the topology of the three-phase resonant compensation network is studied in detail, and the structure of the coupling coil is designed and adjusted. Compared with the single-phase system with the same environmental conditions, air gap, and operating frequency, the simulation results show that the proposed three-phase system can effectively reduce the magnetic flux leakage, reduce the stress in the circuit, and significantly improve the energy transmission efficiency. In order to verify the reliability of the simulation results, an experimental platform was built. The experimental results show that the efficiency and coupling degree of the new system are significantly improved at the resonant frequency of 47.5 kHz, and the stress in the circuit is also significantly reduced.

UV/TiO2 photocatalysis as post-treatment of anaerobic membrane bioreactor effluent for reuse

Advanced oxidation processes have been widely applied as a post-treatment solution to remove residual organic compounds in water reuse schemes. However, UV/TiO2 photocatalysis, which provides a sustainable option with no continuous chemical addition, has very rarely been studied to treat anaerobically treated effluents. In the current study, the removal of organics and nutrients from an anaerobic membrane bioreactor (AnMBR) effluent is evaluated during adsorption and photocatalysis processes under various conditions of TiO2 dose and UV intensity and compared to the effluent from an aerobic membrane bioreactor (AeMBR). The sequence for preferential adsorption on TiO2 was found to be phosphorus, inorganic carbon and then ammonia/organic carbon were found. The competing effect between the organics and nutrients, along with the low UV transmission efficiency caused by the need for high doses of TiO2, ultimately compromise the organic removal efficiency in the AnMBR permeate. TiO2 dosage was found to have a greater impact than UV intensity on improving the overall removal performance as nutrients are competing for the adsorption site but are not photodegraded. Under the same operational condition, the UV/TiO2 photocatalysis displayed a higher removal efficiency of organic matter and phosphorus in the AeMBR effluent due to a lower initial organics concentration and absence of ammonia as compared to the AnMBR effluent.

Low ON-Resistance and High Peak Voltage Transmission Efficiency Based on High-Purity 4H-SiC Photoconductive Semiconductor Switch

Low ON-Resistance and High Peak Voltage Transmission Efficiency Based on High-Purity 4H-SiC Photoconductive Semiconductor Switch

Improved LEACH Protocol Based on Underwater Energy Propagation Model, Parallel Transmission, and Replication Computing for Underwater Acoustic Sensor Networks.

Underwater acoustic sensor networks (UASNs) are critical to a range of applications from oceanographic data collection to submarine surveillance. In these networks, efficient energy management is critical due to the limited power resources of underwater sensors. The LEACH protocol, a popular cluster-based protocol, has been widely used in UASNs to minimize energy consumption. Despite its widespread use, the conventional LEACH protocol faces challenges such as an unoptimized cluster number and low transmission efficiency, which hinder its performance. This paper proposes an improved LEACH protocol for cluster-based UASNs, where the cluster number is optimized with an underwater energy propagation model to reduce energy consumption, and a transmission scheduling algorithm is also employed to achieve conflict-free parallel data transmission. Replication computing is introduced to the LEACH protocol to reduce the signaling in the clustering and data transmission phases. The simulation results show that the proposed protocol outperforms several conventional methods in terms of normalized average residual energy, average number of surviving nodes, average round when the first death node occurs, and the number of packets received by the base station.

Moderate Signal Enhancement in Electrospray Ionization Mass Spectrometry by Focusing Electrospray Plume with a Dielectric Layer around the Mass Spectrometer's Orifice.

Electrospray ionization (ESI) is among the commonly used atmospheric pressure ionization techniques in mass spectrometry (MS). One of the drawbacks of ESI is the formation of divergent plumes composed of polydisperse microdroplets, which lead to low transmission efficiency. Here, we propose a new method to potentially improve the transmission efficiency of ESI, which does not require additional electrical components and complex interface modification. A dielectric plate-made of ceramic-was used in place of a regular metallic sampling cone. Due to the charge accumulation on the dielectric surface, the dielectric layer around the MS orifice distorts the electric field, focusing the charged electrospray cloud towards the MS inlet. The concept was first verified using charge measurement on the dielectric material surface and computational simulation; then, online experiments were carried out to demonstrate the potential of this method in MS applications. In the online experiment, signal enhancements were observed for dielectric plates with different geometries, distances of the electrospray needle axis from the MS inlet, and various compounds. For example, in the case of acetaminophen (15 μM), the signal enhancement was up to 1.82 times (plate B) using the default distance of the electrospray needle axis from the MS inlet (d = 1.5 mm) and 12.18 times (plate C) using a longer distance (d = 7 mm).

Analysis and Experimental Investigation of Steering Kinematics of Driven Steering Crawler Harvester Chassis

In the context of automatic driving, the analysis of the steering motion characteristics is critical for enhancing the efficiency of crawler harvesters. To address issues such as the low transmission efficiency and the large steering radius encountered by traditional crawler harvesters featuring hydrostatic drives, a driven steering crawler harvester chassis was designed. This involved analysis of the chassis transmission system structure and its steering characteristics under several conditions, including differential steering, differential direction reversal, and unilateral braking steering. The steering parameters were determined based on real-time kinematic positioning–global navigation satellite system (RTK-GNSS) measurements, and they were compared with theoretical predictions based on the crawler harvester steering kinematics. The slip rates and modified models of the crawler chassis for various steering modes were then obtained. The results indicated that the increase in the ratio between the running input and steering input speeds led to larger track steering radii and smaller average rotational angular velocities. Remarkably, the slopes of the linear fits of the tracked chassis steering parameters varied significantly under differential direction reversal and differential steering modes. Compared with the actual results, the correlation coefficient of the tracked chassis steering parameters fitting model is close to 1. The steering parameter model was deemed suitable for actual operational requirements. The results provide a valuable reference for designing navigation and steering models of crawler harvesters operating on different road surfaces.

Mechanical Metamaterials for Handwritten Digits Recognition.

The increasing needs for new types of computing lie in the requirements in harsh environments. In this study, the successful development of a non-electrical neural network is presented that functions based on mechanical computing. By overcoming the challenges of low mechanical signal transmission efficiency and intricate layout design methodologies, a mechanical neural network based on bistable kirigami-based mechanical metamaterials have designed. In preliminary tests, the system exhibits high reliability in recognizing handwritten digits and proves operable in low-temperature environments. This work paves the way for a new, alternative computing system with broad applications in areas where electricity is not accessible. By integrating with the traditional electronic computers, the present system lays the foundation for a more diversified form of computing.

Improving the liquid phase exfoliation efficiency of graphene based on the enhanced intermolecular and interfacial interactions

The liquid phase exfoliation (LPE) technique presents significant advantages and potential for the large-scale production of high-quality graphene nanosheets (GNs) with minimal defects. Nevertheless, the Hansen solubility parameters and surface tension matched principle were limited the range of suitable solvents for LPE process. As a result, commonly employed solvents such as N-methyl-2-pyrrolidone (NMP) and N, N-Dimethylformamide (DMF) exhibit low viscosity, leading to a low transmission efficiency of shear force from solvent to graphite, resulting in inadequate shear force and low exfoliation efficiency. In this work, to break through limitations of existing solvent systems, we investigate the influence of solvent viscosity on the LPE efficiency in various pyrrolidone solvents, which share similar structures with NMP but have longer molecular chains and higher viscosity. When compared to the NMP system, the concentration of GNs in the N-octyl-2-pyrrolidone (NOP) suspension system exhibits a significant increase of approximately 70 %, which primarily attributed to the higher intermolecular and interfacial interactions in NOP suspension. Moreinterestingly, the interactions could be further intensified by reducing the operating temperature in the NOP suspension system, which leading to an about 150 % improvement in LPE efficiency when compared to the NMP system at standard temperature. Given the remarkable conductivity of GNs, the prepared Cellulose nanofibers/graphene nanosheets (CNF/GNs) composite film exhibits lightweight and efficient electromagnetic shielding performance of 2.4 × 104 dB cm2 g−1.This work is expected to establish a universal and efficient pathway for the economical and high-yield production of GNs, elucidating the microscopic mechanism by which molecular conformation at the solid–liquid interface influences the transfer of shear forces from solvent to graphite, thereby promoting the development of widespread applications of GNs ang other two-dimensional (2D) nanomaterials.

Novel Auxiliary Resonant Pole Inverter and its Optimal Control Strategy

Conventional inverters operate in hard‐switching mode, and as the switching frequency increases, the switching losses increase dramatically. Increasing the switching frequency helps reduce the size and cost of the inverter, but too high a switching frequency generates greater switching losses, which affects the inverter's transmission efficiency. In response to the problem that conventional hard‐switching inverters cannot be higher in frequency and have high switching losses and low transmission efficiency, an optimized auxiliary resonant commutated inverter and control strategy are proposed to make the inverter work in soft‐switching mode, which helps reduce the switching losses. The auxiliary converters in the bridge arm topology of each phase of the three‐phase inverter are divided into two groups, and the operating auxiliary converters are selected according to the direction of the load current. When the load current direction is positive, the upper bridge arm auxiliary device works and the lower bridge arm auxiliary device turns off, similarly when the load current direction is negative, the lower bridge arm auxiliary device works and the upper bridge arm auxiliary device turns off, this can ensure that only one group of devices works every half cycle, making the control strategy simple and reducing auxiliary circuit losses. Simulation and experimental verification of the effectiveness of the proposed scheme. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中国电力企业远程用电检查技术的应用现状及对策

With the rapid development of the power industry, remote power inspection technology has been widely used in the power industry. The application of remote power inspection technology is of great significance to the development of the power industry, so the power enterprises should strengthen the research and development and application of this technology to improve the safety and stability of the power system. Firstly, this paper briefly analyzes and expounds the technology and current situation of remote power consumption, and summarizes a series of problems existing in remote power consumption inspection, including low transmission efficiency of power consumption information caused by differences in communication equipment and technology, inaccurate power consumption inspection caused by the ability and quality of operators in practical operation, and inaccurate inspection caused by imperfect power consumption inspection equipment system. Finally, through the analysis of the above problems, the author puts forward the relevant problem-solving practice strategy. Electric power enterprises should strengthen the construction of information infrastructure, improve the efficiency of electricity information transmission, timely update the electricity inspection system, encourage the innovation and practical operation of the electricity system, and provide a more perfect development idea for the development of China’s electric power industry.

Active acoustic field modulation of ultrasonic transducers with flexible composites

The simple acoustic field generated by conventional transducers limits the development of ultrasound applications. Current methods rely on passive acoustic lenses or active arrays to manipulate ultrasonic waves, but they face challenges such as low transmission efficiency with bulky morphology for lenses, and complex systems with high-cost for arrays. Here, we propose a method exploiting flexible piezoelectric ultrasonic transducers (FPUT) with 1-3 PZT8/PDMS composites to achieve a high-frequency and diversified ultrasonic field. The FPUT at a center frequency of 1.5 MHz exhibits a high electromechanical coupling coefficient (kt ~ 0.74), excellent transmission efficiency, and mechanical conformability. We showcase two dynamic functionalities of our setup, namely variable acoustic focus and multi-order vortex generated by circular and spiral shape transducers. Finally, we show that the FPUT achieves high-resolution underwater ultrasonic imaging at a wide spatial range (>12λ) via ultrasonic collimation, offering a viable technological alternative for active acoustic fields manipulation and ultrasonic applications.

The research of a multi-stage roller type magnetorheological transmission device on temperature properties

Magnetorheological Transmission Device (MRTD) is a controllable power regulation device using magnetorheological fluid as the transmission medium. It has characteristics of fast response, a wide range of speed regulations, and a pollution-free environment. The traditional pairwise transmission structure has serious heat generation problems during operation, resulting in low transmission efficiency. Therefore, we innovatively propose a multi-stage roller type MRTD to improve the heat generation problem fundamentally. The steady-state and transient temperature fields of the multi-stage roller type MRTD are simulated using the thermal analysis module in ANSYS based on the temperature field formulation. The variations of internal temperature at different slip powers are obtained. The results show that the designed multi-stage roller type MRTD has a good suppression of temperature rise. This study can provide a new approach to improve the thermal performance of MRTD.

3D printing of plasmonic nanofocusing tip enabling high resolution, high throughput and high contrast optical near-field imaging

Scanning near-field optical microscopy (SNOM) offers a means to reach a fine spatial resolution down to ~ 10 nm, but unfortunately suffers from low transmission efficiency of optical signal. Here we present design and 3D printing of a fiber-bound polymer-core/gold-shell spiral-grating conical tip that allows for coupling the inner incident optical signal to the outer surface plasmon polariton with high efficiency, which then adiabatically transport, squeeze, and interfere constructively at the tip apex to form a plasmonic superfocusing spot with tiny size and high brightness. Numerical simulations and optical measurements show that this specially designed and fabricated tip has 10% transmission efficiency, ~ 5 nm spatial resolution, 20 dB signal-to-noise ratio, and 7000 pixels per second fast scanning speed. This high-resolution, high throughput, and high contrast SNOM would open up a new frontier of high spatial-temporal resolution detecting, imaging, and monitoring of single-molecule physical, chemical, and biological systems, and deepen our understanding of their basic science in the single-molecule level.

A new method for the analysis of access period experiments, illustrated with whitefly-borne cassava mosaic begomovirus.

Reports of low transmission efficiency, of a cassava mosaic begomovirus (CMB) in Bemisia tabaci whitefly, diminished the perceived importance of whitefly in CMB epidemics. Studies indicating synergies between B. tabaci and CMB prompt a reconsideration of this assessment. In this paper, we analysed the retention period and infectiousness of CMB-carrying B. tabaci as well as B. tabaci susceptibility to CMB. We assessed the role of low laboratory insect survival in historic reports of a 9d virus retention period. To do this, we introduced Bayesian analyses to an important class of experiment in plant pathology. We were unable to reject a null hypothesis of life-long CMB retention when we accounted for low insect survival. Our analysis confirmed low insect survival, with insects surviving on average for around three days of transfers from the original infected plant to subsequent test plants. Use of the new analysis to account for insect death may lead to re-calibration of retention periods for other important insect-borne plant pathogens. In addition, we showed that B. tabaci susceptibility to CMB is substantially higher than previously thought. We also introduced a technique for high resolution analysis of retention period, showing that B. tabaci infectiousness with CMB was increasing over the first five days of infection.