Use Of Radiofrequency Research Articles

Altering Conformational States of Dynamic Ion Populations using Traveling Wave Structures for Lossless Ion Manipulations.

With its capacity to store and translate ions across considerable distances and times, traveling wave structures for lossless ion manipulations (TW-SLIM) provide the foundation to expand the scope of ion mobility spectrometry (IMS) experiments. While promising, the dynamic electric fields and consequential ion-neutral collisions used to realize extensive degrees of separation have a considerable impact on the empirical results and the fundamental interpretation of observed arrival time distributions. Using a custom-designed set of TW-SLIM boards (∼9 m) coupled with a time-of-flight mass spectrometer (SLIM-ToF), we detail the capacity to systematically alter the gas-phase distribution of select peptide conformers. In addition to discussing the role charge-transfer may play in TW-SLIM experiments that occur at extended time scales, the ability of the SLIM-ToF to perform tandem IMS was leveraged to confirm that both the compact and elongated conformers of bradykinin2+ undergo interconversion within the SLIM. Storage experiments in which ions are confined within SLIM using static potential wells suggest that factors aside from TW-induced ion motion contribute to interconversion. Further investigation into this matter suggests that the use of radio frequency (RF) fields to confine ions within SLIM may play a role in ion heating. Aside from interconversion, storage experiments also provide insight into charge transfer behavior over the course of extended periods. The results of the presented experiments suggest that considerations should be taken when analyzing labile species and inform strategies for the TW-SLIM design and method development.

Pemanfaatan Radio Frequency Identification dan Near Field Communication pada PKK Pondok Rajeg Residence

PKK is an abbreviation for Family Empowerment and Welfare, a national movement in community development that grows from, by and for the community towards the realization of a healthy, prosperous family, environmental awareness, faith and devotion to God Almighty. Based on the results of interviews and observations carried out by the community service team, it is known that various problems exist within the Pondok Rajeg Residence PKK, that so far, Pondok Rajeg Residence PKK members are still experiencing difficulties in carrying out innovations in entrepreneurship. Pondok Rajeg Residence PKK members are still doing it manually to view profiles. and menus for sale. Therefore, the team proposing community service considers it necessary to provide understanding in the introduction and use of Radio Frequency and Near Field Communication in order to make it easier for administrators and members to provide entrepreneurial services to the PKK Pondok Rajeg Residence.

2.4 GHz Rectifier Antenna for Radiofrequency-based Wireless Power Transfer: Recent Developments, Opportunities, and Challenges

The use of radio frequency (RF) energy for wireless power transfer (WPT) has gained significant attention in recent years due to its potential for powering electronic devices without the need for wires or batteries. A key component of RF-based WPT systems is the rectenna, which converts RF energy into usable DC power. This article provides an overview of recent developments, opportunities, and challenges in the design of 2.4 GHz rectennas for RF-based WPT applications. We have searched major online libraries extensively for studies regarding the 2.4 GHz rectenna. As a result, 35 high-quality studies published between 2010 and 2023 were gathered. In the discussion section, we begin by presenting the basic principles of rectenna design and the key parameters that affect its performance, such as the antenna characteristics, rectifier capabilities, and nonlinearity properties of the rectifier. We then highlighted recent advancements in rectenna design, including novel approaches for improving efficiency and power transfer capability, such as the involvement of hybrid solar cell-rectenna structures, transistor-based rectifiers, and bridge rectifiers. Finally, the article concludes by identifying future opportunities, research directions, and open challenges in the design and optimization of rectennas for RF-based WPT, including the development of compact, low-cost, and high-performance rectennas for a wide range of applications. Overall, this article provides a comprehensive overview of the state-of-the-art of 2.4 GHz rectenna design for RF-based WPT and highlights the exciting opportunities and challenges for this rapidly growing field.

Enhanced Traffic Management for Emergency Vehicle Information Transmission using Wireless Sensor Networks

Considerable research has been conducted in over a decade on traffic management systems that utilize Wireless Sensor Networks (WSNs) to mitigate congestion and prioritize emergency vehicles. The traffic management is becoming a wide interesting area for both academic and industrial researchers. The real-time traffic management is a dynamic scheme and is very challenging to provide an accurate signalling time and priority for a specific vehicle. This paper introduces a novel emergency vehicle information passing system that utilizes Radio Frequency (RF) sensors. This research study presents an innovative system for transmitting emergency vehicle information, which makes use of Radio Frequency (RF) sensors. The system effectively transmits crucial data, such as vehicle ID, approaching direction, mileage driven, and destination time. By doing so, it enables other vehicles to allocate appropriate space and facilitate smoother passage for emergency vehicles. The main intention of this approach is to improve the communication speed among the nodes and to reduce the response time. The communication among the nodes is done with different frequencies to enhance the method's effectiveness. We also propose a priority-based MAC (PMAC), which guarantees a slot allocation for emergency message transmission in the network. The effectiveness of the proposed approach is assessed through simulation using NS-2. The findings emphasize the effectiveness of the RF sensor when it comes to its ability to respond quickly and showcasing the PMAC's capability to reduce end-to-end delay.

Correction of age-related changes of the face skin using radiofrequency micro needling. Brief literature review

The problem of choosing a method for skin rejuvenation remains relevant despite a wide selection of conservative and surgical methods for eliminating age-related changes. In recent years, treatment methods for voluminous and traumatic ones have been striving for minimally invasive, quickly feasible with an optimal result that should meet both the needs of patients and doctors. For this reason, injection and hardware methods of rejuvenation began to come to the fore, especially when correcting changes on the face. Cosmetic devices based on radiofrequency can compete in efficiency with laser technology, having their own specific advantages.
 The aim of the work was to evaluate the available literature sources related to the use of radiofrequency in dermatology and dermatocosmetology, especially for leveling age-related changes in the skin of the face.
 The available literature sources from Russian and foreign databases (Elibrary, PubMed, Google Academia) were analyzed on the use of radiofrequency and radiofrequency micro needling in dermatocosmetology for facial skin rejuvenation.
 The analysis showed the widespread use of radio frequency in dermatocosmetology, its high efficiency and safety, however, there are very few full-fledged studies devoted to radio frequency microneedling.
 In our opinion, radiofrequency microneedling is a significant step forward compared to traditional radiofrequency devices, especially for facial skin rejuvenation by increasing the safety and effectiveness of the procedure. The use of radiofrequency microneedling can be effective for correcting age-related skin changes, especially in the face area, both as monotherapy and in combination with other methods of rejuvenation.

Synthesis of hexagonal boron nitride thin film on Pt substrates for resistive switching memory applications

Hexagonal boron nitride (hBN), due to its high reliability as a two-dimensional (2D) dielectric material, has attracted much attention for its potential applications in nanoelectronic devices. Here, the use of radio frequency (RF) magnetron sputtering-grown hBN films to construct hBN-based resistive switching (RS) memory device is reported, and the RS mechanism is deduced. The hBN-based RS memory shows low operating voltage, reproducible write cycles, and long retention time. First-principles simulations further confirm the resistive switching. This work provides an important case to facilitate the future applications of 2D materials in the RS memory.

Neuronal activity under transcranial radio-frequency stimulation in metal-free rodent brains in-vivo

As the use of Radio Frequency (RF) technologies increases, the impact of RF radiation on neurological function continues to receive attention. Whether RF radiation can modulate ongoing neuronal activity by non-thermal mechanisms has been debated for decades. However, the interactions between radiated energy and metal-based neural probes during experimentation could impact neural activity, making interpretation of the results difficult. To address this problem, we modified a miniature 1-photon Ca2+ imaging device to record interference-free neural activity and compared the results to those acquired using metal-containing silicon probes. We monitored the neuronal activity of awake rodent-brains under RF energy exposure (at 950 MHz) and in sham control paradigms. Spiking activity was reliably affected by RF energy in metal containing systems. However, we did not observe neuronal responses using metal-free optical recordings at induced local electric field strengths up to 230 V/m. Our results suggest that RF exposure higher than levels that are allowed by regulatory limits in real-life scenarios do not affect neuronal activity.

CornerRadar

Unmanned robots are increasingly used around humans in factories, malls, and hotels. As they navigate our space, it is important to ensure that such robots do not collide with people who suddenly appear as they turn a corner. Today, however, there is no practical solution for localizing people around corners. Optical solutions try to track hidden people through their visible shadows on the floor or a sidewall, but they can easily fail depending on the ambient light and the environment. More recent work has considered the use of radio frequency (RF) signals to track people and vehicles around street corners. However, past RF-based proposals rely on a simplistic ray-tracing model that fails in practical indoor scenarios. This paper introduces CornerRadar, an RF-based method that provides accurate around-corner indoor localization. CornerRadar addresses the limitations of the ray-tracing model used in past work. It does so through a novel encoding of how RF signals bounce off walls and occlusions. The encoding, which we call the hint map, is then fed to a neural network along with the radio signals to localize people around corners. Empirical evaluation with people moving around corners in 56 indoor environments shows that CornerRadar achieves a median error that is 3x to 12x smaller than past RF-based solutions for localizing people around corners.

DC Power Line Communication (PLC) on 868 MHz and 2.4 GHz Wired RF Transceivers.

Efficient management through monitoring of Li-ion batteries is critical to the progress of electro-mobility and energy storage globally, since the technology can be hazardous if pushed beyond its safety boundaries. Battery management systems (BMSs) are being actively improved to reduce size, weight, and cost while increasing their capabilities. Using power line communication, wireless monitoring, or hybrid data links are one of the most advanced research directions today. In this work, we propose the use of radio frequency (RF) transceivers as a communication unit that can deliver both wired and wireless services, through their superior analog and digital signal processing capability compared to PLC technology. To validate our approach computational simulation and empirical evaluation was conducted to examine the possibility of using RF transceivers on a direct current (DC) bus for wired BMS. A key advantage of this study is that it proposes a flexible and tested system for communication across a variety of network scenarios, where wireless data links over disrupted connections may be enabled by using this technology in short-range wired modes. This investigation demonstrates that the IEEE 802.15.4-compliant transceivers with operating frequencies of 868 MHz and 2.4 GHz can establish stable data links on a DC bus via capacitive coupling at high data rates.

Application of Radiofrequency for Decolorization, Floc Formation, and Microorganism Inactivation

The use of radio frequency for water and wastewater treatment is a topic that has not been extensively explored. In this study, the effect of a HydroFlow S38 device (Hydropath Holdigs) inducing 150 KHz radio frequency (RF) has been investigated, removing color, forming coagulant flocs and their sedimentation, and the removal of bacteria. Experiments were first conducted on synthetic samples, and then on landfill leachate from the Aradkooh waste processing and landfilling complex (Kahrizak) in Tehran, Iran. The results of the experiments showed that RF had little to no effect on de-coloring in the absence or presence of sodium hypochlorite. Also, the coagulation and flocculation of ferric chloride remained unaffected. However, the use of RF was shown to reduce the number of bacteria significantly. The inductance of RF alone, without any other aid or chemical/physical treatment, was able to reduce the bacterial count by 35%. These findings provide motivation for future research regarding the use of RF for bacteria inactivation.

Resource Allocation for Simultaneous Wireless Information and Power Transfer Systems: A Tutorial Overview

Over the last decade, simultaneous wireless information and power transfer (SWIPT) has become a practical and promising solution for connecting and recharging battery-limited devices due to significant advances in low-power electronics technology and wireless communications techniques. To realize the promised potentials, advanced resource allocation design plays a decisive role in revealing, understanding, and exploiting the intrinsic rate–energy tradeoff capitalizing on the dual use of radio frequency (RF) signals for wireless charging and communication. In this article, we provide a comprehensive tutorial overview of SWIPT from the perspective of resource allocation design. The fundamental concepts, system architectures, and RF energy harvesting (EH) models are introduced. In particular, three commonly adopted EH models, namely, the linear EH model, the nonlinear saturation EH model, and the nonlinear circuit-based EH model, are characterized and discussed. Then, for a typical wireless system setup, we establish a generalized resource allocation design framework that subsumes conventional resource allocation design problems as special cases. Subsequently, we elaborate on relevant tools from optimization theory and exploit them for solving representative resource allocation design problems for SWIPT systems with and without perfect channel state information (CSI) available at the transmitter, respectively. The associated technical challenges and insights are also highlighted. Furthermore, we discuss several promising and exciting future research directions for resource allocation design for SWIPT systems intertwined with cutting-edge communication technologies, such as intelligent reflecting surfaces, unmanned aerial vehicles, mobile edge computing, federated learning, and machine learning.

State-of-the-Art Techniques in RF Energy Harvesting Circuits

The exigency for continuous use of electrical devices has created greater demands for electricity along with more efficient transmission techniques. Energy from natural resources can be solar, thermal, vibration, friction, or Radio Frequencies (RF) signals. This state-of-the-art work provides a summary of RF energy harvesting techniques and can be used as a guide for the manufacture of RF energy scavenging modules. The use of Radio Frequency (RF) Energy Harvesting (EH) technique contributes to the development of autonomous energy devices and sensors. A rectenna system includes three main units: the receiving antenna, the impedance matching network, and the rectifier. We thoroughly analyze how to design a rectenna system with special emphasis given on the design of the rectifier. At the same time many works of the last 10 years are presented. This review article categorizes the used topologies depending on the type of antennas, IMNs, and rectifiers and comparatively presents their advantages and disadvantages.

RF-Wri: An Efficient Framework for RF-Based Device-Free Air-Writing Recognition

Machines are becoming indispensable in our lives and the requirements of the human-machine interactions are increasing. Conventional devices, such as a keyboard or touch screen, may not be preferred in future’s entertainment, home, and industrial applications. Device-free (non-contact) solutions will be even more popular. These solutions often use visual and acoustic technologies which have some disadvantages. The use of radio frequency (RF) waves for human-machine interaction such as air-writing (Wri), is a new and challenging problem. We propose a device-free machine learning-based air-writing recognition framework called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RF-Wri</i> which can effectively distinguish 26 capital letters. Two-channel low-cost software-defined radios (SDR) and oppositely polarized antennas are used to provide polarization diversity which makes the accuracy of classification superior. Another critical novelty is the usage of Discrete Cosine Transform (DCT) coefficients as new features to represent RF waveform which provides writing speed and user invariant recognition. Discrete Wavelet Transform (DWT) filters and letter segmentation algorithm are used for signal de-noising and separating the air-writing activities, respectively. It is shown that Support Vector Machine (SVM) can successfully classify the measured RF waves of air-written letters. It is verified with various real measurements that the proposed framework, RF-Wri, achieves 95.15% accuracy in the classification of all 26 air-written letters and outperforms the fairly new WiFi-based air-writing recognition approaches.

Disruption avoidance via radio frequency current condensation in magnetic islands produced by off-normal events

This paper discusses the use of radio frequency (RF) current drive to stabilize large islands, focusing on nonlinear effects that appear when relatively high powers are used to stabilize large islands. We are interested in developing a capability to stabilize large islands via RF driven currents to avoid the need for mitigation to the extent possible. As tokamaks are designed and built with increasing levels of stored energy in the plasma, disruptions become increasingly dangerous. It has been reported that 95% of the disruptions in the Joint European Torus tokamak with the ITER-like wall are preceded by the growth of large locked islands. These large islands are mostly produced by off-normal events other than neoclassical tearing modes. This paper presents theory and modeling for a nonlinear “RF current condensation” effect that can concentrate the RF driven current near the center of a large island, thereby increasing the efficiency of the stabilization. A nonlinear shadowing effect can hinder the stabilization of islands if the aiming of the ray trajectories does not properly consider the nonlinear effects.

A New Wide-Area Monitoring System of Electromagnetic Fields Around Megawatt-Class Amplifiers for Ion Cyclotron Range of Frequency Heating at a Fusion Test Facility

Nuclear fusion research requires the production of high-temperature plasma. One of the plasma heating methods is the use of radio frequency (RF) waves. The RF wave heating system uses a high-power amplifier, which poses a concern about the leakage electromagnetic fields. Therefore, a new wide-area multipoint electromagnetic monitoring system using personal RF monitors has been developed. The developed monitoring system was applied to the megawatt-class amplifiers for the “ion cyclotron range of frequency” (ICRF) heating system in the frequency range of ion cyclotron resonance from 30 to 40 MHz. As a result, the leakage magnetic field was less than the measurement sensitivity during the plasma experiment, in which the leakage electric field was detected with sufficient sensitivity. The leakage electric field becomes larger as the RF forward power increases, and thus the electric field would be radiated through the stub and/or high voltage supply line connected to the anode of tetrode in the ICRF amplifier. The electric field around the ICRF amplifiers did not exceed the reference level of International Commission on Non-Ionizing Radiation Protection (ICNIRP). The developed wide-area multipoint monitoring system will be useful for monitoring the leakage RF electromagnetic fields around the ICRF heating system at the future fusion devices.

Energy-Efficient Hybrid Symbol-Level Precoding for Large-Scale mmWave Multiuser MIMO Systems

We address the symbol-level precoding design problem for the downlink of a multiuser millimeter wave (mmWave) multiple-input multiple-output (MIMO) wireless system where the transmitter is equipped with a large-scale antenna array. The high cost and power consumption associated with the massive use of radio frequency (RF) chains prohibit fully-digital implementation of the precoder, and therefore, we consider a hybrid analog-digital architecture where a small-sized baseband precoder is followed by two successive networks of analog on-off switches and variable phase shifters according to a fully-connected structure. We jointly optimize the digital baseband precoder and the states of the switching network on a symbol-level basis, i.e., by exploiting both the channel state information (CSI) and the instantaneous data symbols, whereas the phase-shifting network is designed only based on the CSI due to practical considerations. Our approach to this joint optimization is to minimize the Euclidean distance between the optimal fully-digital and the hybrid symbol-level precoders. Remarkably, the use of a switching network allows for power-savings in the analog precoder by switching some of the phase shifters off according to the instantaneously optimized states of the switches. Our numerical results indicate that, on average, up to 50 percent of the phase shifters can be switched off. We provide an analysis of energy efficiency by adopting appropriate power dissipation models for the analog precoder, where it is shown that the energy efficiency of precoding can substantially be improved thanks to the phase shifter selection approach, compared to the fully-digital and the state-of-the-art hybrid symbol-level schemes.

Effect of radio frequency heating on the mortality of Rhizopertha dominica (F.) and its impact on grain quality

The use of radio frequency (RF) heating to reach temperatures lethal to stored product pests has significant potential. We examined the lethal effects of RF on the stored grain pest, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), under four different RFs, three types of grain, and different moisture contents of rice. The quality of two rice cultivars, after RF heating, was also tested. When heated to 58 °C by RF, R. dominica adult mortality reached 100%. The mortality of R. dominica adults reached 100%. The fastest mortality rate occurred at 50–52 °C. With an increase in RF, the time needed to attain a lethal temperature decreased. The heating time to reach 100% mortality differed among the three types of grain; for example, the heating time of wheat was faster than corn or rice. Kernel size and chemical composition was the main factor influencing the RF lethal rate in the different types of grain under the same experimental conditions. There was a significant linear relationship between moisture content (m.c.) and heating time (Y = −38.05 X + 15.501, R = 0.9803) in rice. RF heating of rice to 58 °C did not significantly affect milling quality, storage quality, or seed quality. Thus, heating time, types of grain, and the m.c. of the grains are three important factors that should be considered in RF heating to control stored product pests. These results indicate that RF heating could be an effective physical method for killing stored grain pests.

Radiofrequência associada í drenagem linfática manual no rejuvenescimento facial

Objetivo: Verificar a efetividade da radiofrequência associada a drenagem linfática manual no rejuvenescimento facial. Métodos: Tratou-se de um estudo do tipo longitudinal e de caráter intervencionista na Universidade de Fortaleza (UNIFOR) no perí­odo de agosto í outubro de 2019. As participantes foram recrutadas de um banco de dados, totalizando uma amostra de 2 voluntárias e 8 sessões. Os dados foram coletados através de ficha de avaliação, fotos comparativas a fim de verificar os resultados obtidos com o tratamento. A pesquisa foi aprovada pelo Comitê de Ética da UNIFOR sob número de parecer 3.570.017. Resultados: Notou-se melhora nos aspectos da pele como, melhora do contorno facial, hidratação, preenchimento de sulcos, linhas e redução de edema facial. Conclusão: O uso da radiofrequência associada a drenagem linfática mostrou-se benéfico no envelhecimento cutâneo. Sugere-se que um maior número de voluntários e sessões sejam realizadas a fim de obter resultados ainda mais significativos.

Literature Study of Harvesting Energy with Resources Radio Frequency

Energy harvesting is the process of harvesting energy from external sources such as solar energy, heat, wind and electromagnetic waves / radio frequencies. dimension. Research on harvesting energy needs to be developed because the use of non-renewable energy is increasingly limited. The use of radio frequency (RF) as a source of energy for harvesting is an effort to create environmentally friendly energy. This is due to the growing use of telecommunications technology. Various studies have been conducted by harvesting RF from various telecommunication signals and broadcasting media (AM / FM, TV / DTV, GSM signals, Wi-Fi signals). The purpose of writing this article is to study literature on the use of harvesting energy, especially those originating from radio / RF frequencies. A simple harvesting energy harvesting system consists of an antenna and a voltage rectifier circuit. The antennas used for RF energy harvesting have different designs according to the type of signal captured, including using periodic log antennas, archimedean spiral antennas, patch antennas, dipole patch antennas and vivaldi antennas. The energy yield obtained from the energy harvesting process with radio frequency sources tends to be small in the milliwatt scale (1.17 µW / cm2 - 20VDC) depending on the type of antenna and radio frequency used (0.3 - 27.5 GHz) and can be applied to low power electronic devices.

Application of Artificial Neural Networks for Accurate Determination of the Complex Permittivity of Biological Tissue.

Medical devices making use of radio frequency (RF) and microwave (MW) fields have been studied as alternatives to existing diagnostic and therapeutic modalities since they offer several advantages. However, the lack of accurate knowledge of the complex permittivity of different biological tissues continues to hinder progress in of these technologies. The most convenient and popular measurement method used to determine the complex permittivity of biological tissues is the open-ended coaxial line, in combination with a vector network analyser (VNA) to measure the reflection coefficient (S11) which is then converted to the corresponding tissue permittivity using either full-wave analysis or through the use of equivalent circuit models. This paper proposes an innovative method of using artificial neural networks (ANN) to convert measured S11 to tissue permittivity, circumventing the requirement of extending the VNA measurement plane to the coaxial line open end. The conventional three-step calibration technique used with coaxial open-ended probes lacks repeatability, unless applied with extreme care by experienced persons, and is not adaptable to alternative sensor antenna configurations necessitated by many potential diagnostic and monitoring applications. The method being proposed does not require calibration at the tip of the probe, thus simplifying the measurement procedure while allowing arbitrary sensor design, and was experimentally validated using S11 measurements and the corresponding complex permittivity of 60 standard liquid and 42 porcine tissue samples. Following ANN training, validation and testing, we obtained a prediction accuracy of 5% for the complex permittivity.