Frequency Resonance Research Articles

Helicity-Preserving Optical Metafluids.

A colloidal suspension of photonic nanostructures exhibiting optical magnetism is dubbed an optical metafluid. A promising constituent of a metafluid is a nanosphere of high-refractive index dielectrics having the magnetic-type Mie resonances in the optical frequency. At the Kerker conditions, a dielectric nanosphere satisfies the electromagnetic duality symmetry condition and preserves the handedness of circularly polarized incident light. A metafluid of such dielectric nanospheres thus preserves the helicity of incident light. In the helicity-preserving metafluid, the local chiral fields around the constituent nanospheres are strongly enhanced, which improves the sensitivity of enantiomer-selective chiral molecular sensing. Here, we experimentally demonstrate that a solution of crystalline silicon nanospheres can be "dual" and "anti-dual" metafluids. We first theoretically address the electromagnetic duality symmetry of single silicon nanospheres. We then produce solutions of silicon nanospheres with narrow size distributions and experimentally demonstrate the "dual" and "anti-dual" behaviors.

Noise reduction and power generation in blower duct using Helmholtz resonator with piezoelectric diaphragm

Ventilation duct systems are indispensable for air purification and room temperature management in industrial and commercial buildings. The noise generated by blowers for ventilating spaces should be as low as possible. In addition, to power the wireless nodes for monitoring the ventilation conditions such as temperature and pressure at any positions in all the ducts, electric power is preferred to be generated in situ without batteries and wired power supply. In this study, to demonstrate simultaneous noise reduction and in situ power generation using a Helmholtz resonator with a piezoelectric diaphragm in a straight circular pipe duct, the frequency properties of the sound pressure level (SPL) with/without the piezoelectric diaphragm and its generated voltage were measured using an in-house apparatus simulating an industrial blower duct. The experimental results show that the Helmholtz resonator with the piezoelectric diaphragm has a noise reduction performance similar to that without the piezoelectric diaphragm. Power generation was improved not only by impedance matching between the inner and outer resistance but also by the frequency resonance between the frequency of pressure fluctuation in the Helmholtz resonator and the natural frequency of the piezoelectric diaphragm. The Helmholtz resonator with the piezoelectric diaphragm achieved a noise reduction of 10 dB from an SPL of 103 dB and power generation of 12 μW at an SPL of 93 dB.

Patterns of the radiation properties for Peano antennas

This paper studies metallic microstrip antennas with air as a substrate in the UHF band, patterned after space-filling, self-avoiding, and self-similar (FASS) Peano curves. Our novel study is based on context-free grammar and genetic programming as computing tools to unravel the role of geometry on both; the Voltage Standing Wave Ratio (VSWR<2) and frequency resonance patterns for Peano antennas. We use in our approach the numeric method of moments (MoM) implemented in Matlab 2021a to solve the corresponding Maxwell equations. Novel equations for the patterns of both features (resonance frequencies and frequencies such that the VSWR<2) are provided as functions of the characteristic length L. Antennas spanning a Ltimes L area (Lle 0.1,m), feeding points set at seven places, and three widths of the metallic strip are introduced as instances of our approach. Finally, a Python 3.7 application is constructed to facilitate the extension and use of our results.

Research on vibration mechanism of the low-to-medium-speed maglev train-track-at-ground-structure system

The at-ground-structure supports the maglev track on the subgrade segment and receives the subgrade’s equally distributed elastic support to ensure the holding track running of the maglev train. A complicated maglev train-track-at-ground-structure coupled system is produced, negatively affecting the stable operation of the train. To explore the vibration mechanism, an elaborate maglev train-track-at-ground-structure coupled system was established considering active levitation control, and field tests confirmed the reliability of the numerical method. Firstly, the natural frequencies of track-at-ground-structure were investigated. Then, characteristics of this coupled system were examined in terms of its dynamic interaction mechanism, dynamic response characteristics and vibration frequency spectrum distribution. Finally, the vehicle-induced resonance mechanism and anti-vibration methods of the at-ground-structure were analyzed. The results show that the high-frequency vibrations exist in both the F-rail and at-ground-structure obviously, and create varied wavelengths affecting the maglev train’s running stability. The high frequency resonance phenomena easily produce when loading frequency of neighboring levitation forces is near to fundamental frequency of at-ground-structure, and disappears while the two frequencies are avoided.

Ultrahigh microwave frequency resonance of Y2Co17 thin film with planar anisotropy

Y2Co17 thin films grown along the c axis with planar anisotropy were fabricated by magnetron sputtering and annealed by vacuum heat treatment with rapid water-cooling technologies. The results demonstrate that the annealing temperature had a significant impact on structures and morphologies of the films. The phase structure transformed from rich fcc-Co phase to Y2Co17 intermetallic compounds with the increasing annealing temperature. The Y2Co17 thin film annealed at 600 °C has a saturation magnetization of around 13.5 kGs and a negative magneto-crystalline anisotropy constant of −1.88 × 106 erg/cm3, respectively. The high-frequency performance of the film show that, in the absence of an induced in-plane anisotropy field, the zero-field natural resonance frequency exceeds 4 GHz.

Numerical modelling of resonance mechanisms in jointed rocks using transfer functions

Resonance effects in parallel jointed rocks subject to stress waves are investigated using transfer functions, derived from signals generated through numerical modelling. Resonance is important for a range of engineering situations as it identifies the frequency of waves which will be favourably transmitted. Two different numerical methods are used for this study, adopting the finite difference method and the combined discrete element-finite difference method. The numerical models are validated by replicating results from previous studies. The two methods are found to behave similarly and show the same resonance effects; one operating at low frequency and the other operating at relatively high frequency. These resonance effects are interpreted in terms of simple physical systems and analytical equations are derived to predict the resonant frequencies of complex rock masses. Low frequency resonance is shown to be generated by a system synonymous with masses between springs, described as spring resonance, with an equal number of resonant frequencies as the number of blocks. High frequency resonance is generated through superposition of multiple reflected waves developing standing waves within intact blocks, described as superposition resonance. While resonance through superposition has previously been identified, resonance based on masses between springs has not been previously identified in jointed rocks. The findings of this study have implications for future analysis of multiple jointed rock masses, showing that a wave travelling through such materials can induce other modes of propagation of waves, i.e. spring resonance.

Analysis of a tuneable NZRI metamaterial unit cell for satellite applications

In this paper, a new single negative metamaterial (MTM) unit cell structure with low profile of 6.2 × 6.2 m2 is proposed. The unit cell shows near zero refractive index (NZRI) characteristics in C, X and Ku bands whereas epsilon negative index (ENG) in Ku-Band frequency. The properties of the proposed MTM unit cell are analysed with the Rogers 5880 substrate which displays low permittivity. To verify the effectiveness of the split ring resonators (SRR) as a metamaterial, a comparison of the unit cell properties in 2 × 3 array structures is created. Besides low profile, tunability performance is shown in the proposed design by adjust the central strip line width of the proposed metamaterial whereas the frequency resonance can be shifted and controlled accordingly. Using commercially available CST software, the reflection (S11) and transmission (S12) parameters of the unit cell are determined. The proposed MTM unit cell can be potentially used in many applications including satellite communication systems.

A Dual Resonance Frequency-Selective Surface Temperature Sensor With Linear Frequency–Temperature Behavior

Metamaterial temperature sensors are receiving increasing attention due to the wireless and passive operation. Unfortunately, the frequency response of most metamaterials sensors to temperature is nonlinear, which increases the complexity of signal processing. A dual resonance frequency selective surface (FSS) temperature sensor with linear frequency-temperature characteristic is proposed in this work. The dual frequency resonance of the sensor is realized by introducing the circular slot unit cell into the substrate integrated waveguide (SIW) structure. The linear relationship between the temperature and the difference in the two resonance frequencies can be achieved at specific condition. The proposed sensor was fabricated and measured from room temperature to 120 °C. Measured resonance frequency of the sensor decreases from 12.658 GHz to 12.57 GHz in SIW cavity resonance mode and from 13.787 GHz to 13.727 GHz in circular slot resonance mode. The experiment result shows that wireless temperature sensing is feasible and that the difference in resonance frequency has a good linear relationship with temperature. The sensitivity of the sensor is 0.309 MHz/°C. This design method can be extended to a wider temperature range and the sensor can be potentially applied in temperature sensing in industrial systems.

Antidote to Vaccine Injuries: “Green Bioelectronics” Generating Antioxidants Broadcasting 528 Frequency Resonance: Homeo/Alchemically-Prepared “Structured Water” Vibrating OxySilverTM Nutraceuticals

Antidote to Vaccine Injuries: “Green Bioelectronics” Generating Antioxidants Broadcasting 528 Frequency Resonance: Homeo/Alchemically-Prepared “Structured Water” Vibrating OxySilverTM Nutraceuticals

High Frequency Resonance Analysis and Resonance Suppression of a Grid-Connected Inverter Coupled With a Long Feeder

With the development of distributed generation (DG) technologies, various inverter-interfaced DG systems have been connected to the grid, which can cause serious harmonic issues. For an inverter-interfaced DG source connected to the grid via a long feeder, multiple resonances may occur due to the non-negligible distributed capacitance of the long line. Multiple resonances can cause current distortions when the DG delivers power to the grid and the harmonic voltage may be amplified because of the resonances. Many inverter control strategies have been studied, but few can suppress harmonics. To solve this issue, this paper derives the voltage transmission equations to analyze the transmission characteristics of harmonic voltages along a long feeder and reveals the reasons for the multiple resonances in the current. Based on the transmission line theory, a new control strategy of inverter is proposed to suppress the multiple resonances in current and the amplification of harmonic voltages. Finally, the effectiveness of the proposed control strategy is verified by the simulation and experimental studies.

Detection of Semi-Solid Materials Utilizing Triple-Rings CSRR Microwave Sensor.

This article proposes the design, fabrication and measurement of a triple-rings complementary split-ring resonator (CSRR) microwave sensor for semi-solid material detection. The triple-rings CSRR sensor was developed based on the CSRR configuration with curve-feed designed together, utilizing a high-frequency structure simulator (HFSS) microwave studio. The designed triple rings CSRR sensor resonates at 2.5 GHz, performs in transmission mode, and senses shift in frequency. Six cases of the sample under tests (SUTs) were simulated and measured. These SUTs are Air (without SUT), Java turmeric, Mango ginger, Black Turmeric, Turmeric, and Di-water, and detailed sensitivity analysis is conducted for the frequency resonant at 2.5 GHz. The semi-solid tested mechanism is undertaken using a polypropylene (PP) tube. The samples of dielectric material are filled into PP tube channels and loaded in the CSRR centre hole. The e-fields near the resonator will affect the interaction with the SUTs. The finalized CSRR triple-rings sensor was incorporated with defective ground structure (DGS) to deliver high-performance characteristics in microstrip circuits, leading to a high Q-factor magnitude. The suggested sensor has a Q-factor of 520 at 2.5 GHz with high sensitivity of about 4.806 and 4.773 for Di-water and Turmeric samples, respectively. The relationship between loss tangent, permittivity, and Q-factor at the resonant frequency has been compared and discussed. These given outcomes make the presented sensor ideal for detecting semi-solid materials.

A 220 GHz-1.1THz continuous frequency and polarization tunable quasi-optical electron paramagnetic resonance spectroscopic system.

Here, we describe a custom-designed quasi-optical system continuously operating in the frequency range 220GHz to 1.1THz with a temperature range of 5-300K and magnetic fields up to 9T capable of polarization rotation in both transmitter and receiver arms at any given frequency within the range through a unique double Martin-Puplett interferometry approach. The system employs focusing lenses to amplify the microwave power at the sample position and recollimate the beam to the transmission branch. The cryostat and split coil magnets are furnished with five optical access ports from all three major directions to the sample sitting on a two-axes rotatable sample holder capable of performing arbitrary rotations with respect to the field direction, enabling broad accessibility to experimental geometries. Initial results from test measurements on antiferromagnetic MnF2 single crystals are included to verify the operation of the system.

SOME ASPECTS OF THE APPLICATION OF THE FREQUENCY- RESONANCE METHOD IN THE DIAGNOSIS AND NEUTRALIZATION OF PATHOGENS

Introduction: The method of bioresonance therapy is now quite widespread and occupies a certain and occupies a certain niche in the medical services market. The goal of the work: to study the possibility of using the frequency resonance method research for the detection of Bifidobacterium and Helicobacter pylori and the impact of frequency resonance on the biological environment.&#x0D; Materials and methods: The hardware complex was used in the work developed on the basis of the National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute» together with employees of the Institute of Applied Problems of Ecology, Geophysics and Geochemistry». On the basis of the clinical diagnostic laboratory of the State Institution of Science «Research and Practical Center of Preventive and Clinical Medicine» State Administrative Department of Ukraine conducted verification of Bifidobacterium and Helicobacter pylori in the in biological media, as well as the study of patients’ blood for sterility according to standard methods. In order to neutralize the pathogens identified during the laboratory the following frequency range was used to neutralize the pathogenic microorganisms detected during the laboratory Х81Х39.2ХХ2 Hz. (X – closed numbers, which will be removed after the protection of intellectual property rights of the authors).&#x0D; Results: Investigation of the possibility of verification of Bifidobacterium and Helicobacter pylori on photographs by frequency resonance method was carried out for the period from October 2021 to January 2022. Comparative analysis of the diagnostic value of the frequency resonance method in comparison with traditional standard methods used in the clinical and diagnostic laboratory of the State Institution of Science «Research and Practical Center of Preventive and Clinical Medicine» State Administrative Department of Ukraine showed a sufficiently high verification probability of more than 96 %.&#x0D; Conclusions: The research conducted requires more thorough additional study with the involvement of medical, biological, physical, and radiophysical scientists.

A Non-Contact Method for Detecting and Distinguishing Chloride and Carbonate Salts Based on Dielectric Properties Using a Microstrip Patch Sensor

A non-contact method for detecting salt concentration in water using a microstrip patch sensor is presented in this work. The microstrip patch sensor, which has a low cost and simple build process, consists of a circular split ring resonator (SRR) with a hole drilled through the substrate in the middle area, and a microstrip patch antenna. The sensor was designed and fabricated using a printed circuit board (PCB) technique based on a negative dry film photoresist and photolithography method. It was built on an Arlon DiClad 880 substrate with a thickness of 1.6 mm and a relative permittivity of 2.2. The resonant frequencies (Fr) and reflection coefficients (S11) in the frequency range from 0.5 GHz to 0.8 GHz were recorded for analysis, both through simulation and experiment. The concentration of chloride and carbonate salts was varied from 0 mg/mL to 20 mg/mL in the tests using the sensor. The statistical analyses of S11 and Fr data obtained from measurements of five different salts at seven different concentrations (using the Shapiro–Wilk test, Bartlett test, and Kruskal–Wallis H test) were conducted using R version 4.2.0 to determine the relationship between the individual salts. The experimental results showed that the frequency response and resonance amplitude are functions of the concentration of each salt. The proposed method has the potential to be used for the non-contact measurement of industrial products, food quality, and health in the future.

Distributions of Resonances of Supercritical Quasi-Periodic Operators

Abstract We discover that the distribution of (frequency and phase) resonances plays a role in determining the spectral type of supercritical quasi-periodic Schrödinger operators. In particular, we disprove the 2nd spectral transition line conjecture of Jitomirskaya in the early 1990s.

The influence of thermo-hygrometric conditions on metamaterials' acoustic performance: an investigation on a 3D printed coiled-up resonator

In the last decades, coiled-up resonators have become popular within the metamaterial research community for narrow band, low frequency resonances combined to subwavelength thickness. Such structures are particularly suited to one of the most widespread manufacturing processes, i.e. PET-based 3D printing. Acoustic performance of coiled-up resonators depends on the geometrical parameters' variation, which is influenced by thermo-hygrometric conditions; however, the deformation itself needs to be further investigated. For this reason, the present paper evaluates the correlation between temperature, relative humidity, and the geometrical parameters' (spiral length and hole diameter) deformations and, consequently, the acoustic performance of a 3D printed coiled-up resonator. A combined approach through analytical, numerical, and experimental measurements quantified the frequency shift of the resonance peaks (within 300 Hz - 5000 Hz) in terms of sound absorption coefficient increasing the temperature (T=10-50° C), and the relative humidity (RH=20-80 %) of the samples. Relative humidity variations turned neglectable discrepancies on sound absorption's peaks. On the other hand, the increase in temperature caused a frequency peaks' shift following an exponential trend: this behavior is straight related to the exponential relationship between the temperature and specific volume function of polyethylene resins.

Extraction and selective promotion of zero-group velocity and cutoff frequency resonances in bi-dimensional waveguides using the electromechanical impedance method

This study showcases the electromechanical impedance (EMI) technique for extracting and promoting zero-group velocity (ZGV) and cutoff frequency resonances in a waveguide structure. We identify the mechanisms of multiple resonances in the EMI spectra via a wave propagation perspective. Both simulation and experiments reveal the fact that sharp resonances in the conductance spectra are associated with either ZGV or cutoff frequency points. Consequently, we design four test configurations to enhance local resonances by aligning induced motions with considered mode shapes. Reasonable agreement between simulation and experiment results is observed. We evaluate the performance of considered configurations in terms of mode enhancement, and configurations that can selectively promote certain mode families are summarized. This study also shines the light on the EMI technique for quantitative non-destructive evaluation (NDE) by potentially supporting the inverse characterization of mechanical properties of host structures.

Gas flares and modern degasation processes in the Arctic seas (on the frequency resonance results-based)

The newly obtained results of the frequency-resonance (FR) technologies application for the study of the sources and processes of seeps and pockmarks formation in the Arctic Region (Norwegian, Barents Sea) and the North Sea are considered. The experimental study of the seepage processes' source formation was carried out using modified methods of the FR-processing, and decoding of satellite images and photographs with the vertical scanning of the cross-sections. The study results of the methane seeps and pockmarks fields show that the intensity and dynamics of their formation partly depend on the inflow of gas fluids from deep sources because of active degassing processes. The use of FR-sounding technologies allows us to remotely determine the spatial regularities of zones of intense gas emission formation and the geological sources of migration probable depth. The study of seep and pockmark field results confirms the significant, but insufficiently taken into account, the influence of crust-mantle gas fluids on the nature and degassing processes features in the structures of the continental margins. New results confirm the crust-mantle gas fluids influence on the nature and degassing processes features in the scan points of Polar marginal structures. These data are important arguments in favor of the "volcanic model" of various structural elements formation in this Region. The FR- technologies data also showed a possibility of seeps and pockmarks use as shallow and deep hydrocarbon field indicators in gas emission areas. These independent data can be used in modeling the deep lithosphere structure and possible mechanisms of abiogenic hydrocarbon formation in Arctic margin structures. We suppose that hydrocarbons through deep channels migrate (from 57 km deep) to the upper crustal horizons where can form hydrocarbon fields. During this migration, gas seeps and pockmarks are formed on the sea bottom and part of the gas can migrate into the atmosphere. Modern degassing centers' studies have confirmed the presence of zones of active migration of gases into the atmosphere, which is an important influencing factor in the dynamics of global climate change processes on Earth. The experience of FR- technologies used in the fields of methane seeps and pockmarks study found in the structures of the Arctic Polar seas showed versatility and the possibility of their use in the study of large gas emissions in structures of different regions.

Design of ideological and political teaching case of analytical chemistry based on EDTA Titrator

Under the background of ideological and political education in the curriculum, according to the requirements of talent training in applied universities, the authors take the analytical chemistry curriculum as the implementation carrier of ideological and political education. Taking case teaching as an innovative means, a teaching case with EDTA as coordination titrant was designed. Based on the explanation of the principle that metal ions and coordination atoms coordinate to form stable compounds in Lewis acid-base theory, the ideological and political education was effectively combined with the teaching point of analytical chemistry knowledge, and the reason why EDTA had wide adaptability was proposed. From the perspective of ideological and political education, the teaching designs carried out with values education as the main line. The curriculum not only imparted professional knowledge, but also guided students' values. A reasonable teaching design can realize the educational goal of the same frequency resonance between professional courses and ideological and political education.

Walk‐to‐Charge Technology: Exploring Efficient Energy Harvesting Solutions for Smart Electronics

Wearable sensors offer great potential in sports, fitness, and medicine. However, their limited battery life poses a major obstacle to their widespread use. This paper explores various energy solutions to extend the battery life of wearable sensors. The first part of the paper focuses on hardware improvements for wearable sensors, such as employing low‐power sensors, energy‐ efficient microcontrollers, and power management circuits. The second part discusses the utilization of solar, thermal, and kinetic energy harvesting techniques to power wearable sensors. These methods aim to harness energy from the environment to supplement or replace battery power. The third part examines wireless power transfer techniques like radio frequency and magnetic resonance, which enable continuous power supply to wearable sensors without the need for physical connections. Software optimization is also highlighted as a crucial aspect in reducing energy consumption. This involves developing efficient algorithms for data processing and transmission, as well as implementing sleep and wake‐up modes to minimize power usage during idle periods. Furthermore, the paper emphasizes the importance of user interaction and behavior in improving energy efficiency. It suggests the development of user‐friendly interfaces and providing users with feedback on their energy usage.