Resonance Cone Research Articles

Ultra-broadband terahertz metamaterial absorber based on a hollow vanadium dioxide circular-truncated cone resonator

Terahertz (THz) broadband metamaterial absorbers with high absorptivity have been of great interest due to their potential applications. However, their limited bandwidth severely hinders their further development and wide applications. To address this issue and achieve ultra-broadband and strong absorption properties at THz frequencies, we present an ultra-broadband THz perfect metamaterial absorber using a hollow vanadium dioxide (VO2) circular-truncated cone array and a VO2 film supported by an Au ground plane. Simulated results show that the absorptivity of the absorber reaches more than 90% in the frequency range of 0.31–10 THz at normal incidence with a relative absorption bandwidth of 188%. At the same time, the average absorptivity in the frequency range reaches 99.2%. The physical origin of broadband perfect absorption has been elucidated by impedance matching theory and wave interference theory, respectively. The electric field distribution is further discussed to explore the physical mechanism of this absorber. Additionally, it also has the characteristics of polarization insensitivity and wide incidence angle stability. The proposed absorber can have many promising applications in the THz region, such as thermal imaging, thermal detection, and cloaking.

Oblique instability of quasi-parallel whistler waves in the presence of cold and warm electron populations

Whistler waves propagating nearly parallel to the ambient magnetic field experience a nonlinear instability due to transverse currents when the background plasma has a population of sufficiently low energy electrons. Intriguingly, this nonlinear process may generate oblique electrostatic waves, including whistlers near the resonance cone with properties resembling oblique chorus waves in the Earth’s magnetosphere. Focusing on the generation of oblique whistlers, earlier analysis of the instability is extended here to the case where low-energy background plasma consists of both a “cold” population with energy of a few eV and a “warm” electron component with energy of the order of 100 eV. This is motivated by spacecraft observations in the Earth’s magnetosphere where oblique chorus waves were shown to interact resonantly with the warm electrons. The main new results are: 1) the instability producing oblique electrostatic waves is sensitive to the shape of the electron distribution at low energies. In the whistler range of frequencies, two distinct peaks in the growth rate are typically present for the model considered: a peak associated with the warm electron population at relatively low wavenumbers and a peak associated with the cold electron population at relatively high wavenumbers; 2) overall, the instability producing oblique whistler waves near the resonance cone persists (with a reduced growth rate) even in the cases where the temperature of the cold population is relatively high, including cases where cold population is absent and only the warm population is included; 3) particle-in-cell simulations show that the instability leads to heating of the background plasma and formation of characteristic plateau and beam features in the parallel electron distribution function in the range of energies resonant with the instability. The plateau/beam features have been previously detected in spacecraft observations of oblique chorus waves. However, they have been attributed to external sources and have been proposed to be the mechanism generating oblique chorus. In the present scenario, the causality link is reversed and the instability generating oblique whistler waves is shown to be a possible mechanism for formation of the plateau and beam features.

Clinical High-Resolution Imaging of the Inner Ear by Using Magnetic Resonance Imaging (MRI) and Cone Beam Computed Tomography (CBCT).

Imaging of the delicate inner ear morphology has become more and more precise owing to the rapid progress in magnetic resonance imaging (MRI). However, in clinical practice, the interpretation of imaging findings is hampered by a limited knowledge of anatomical details which are frequently obscured by artifacts. Corresponding review articles are as rare in journals as they are in reference books. This shortness prompted us to perform a direct comparison of imaging with anatomical whole-mount sections as a reference. It was the intention of this paper to compare the microscopic anatomy of a human inner ear as shown on anatomical whole-mount sections with high-resolution MRI and cone beam computed tomography (CBCT). Both are available in clinical routine and depict the structures with maximum spatial resolution. It was also a goal of this work to clarify if structures that were observed on MRI in a regular manner correlate with factual inner ear anatomy or correspond with artifacts typical for imaging. A fresh human anatomical specimen was examined on a clinical 3-Tesla MRI scanner using a dedicated surface coil. The same specimen was then studied with CBCT. In each imaging modality, high-resolution 3D data sets which enabled multiplanar reformatting were created. In the second step, anatomical whole-mount sections of the specimen were cut and stained. This process enabled a direct comparison of imaging with anatomical conditions. Clinical MRI was able to depict the inner ear with remarkable anatomical precision. Strongly T2-weighted imaging protocols are exquisitely capable of showing the fluid-filled components of the inner ear. The macular organs, ampullar crests and cochlear aqueduct were clearly visible. Truncation artifacts are prone to be confused with the delicate membrane separating the endolymphatic from the perilymphatic compartment. However, it was not possible to directly depict this borderline. With the maximum resolution of magnetic resonance tomography, commonly used in everyday clinical practice, even the smallest details of the inner ear structures can be reliably displayed. However, it is important to distinguish between truncation artifacts and true anatomical structures. Therefore, this study can be useful as a reference for image analysis.

Comparative analysis of installations for heat treatment of non-food pulp raw materials by the influence of electrophysical factors

Relevance. The objectives of the work are to develop radio-hermetic installations and substantiate the effective design of the working chamber, which provides a comprehensive effect of electrophysical factors on non-food pulp raw materials to preserve feed value at reduced operating costs. Scientific tasks: 1) to develop installations with different designs of resonators; 2) to conduct a comparative analysis of the working chambers according to the main parameters; 3) to evaluate the technical and economic indicators of an effective installation in relation to the basic version.Methods. The effect of electrophysical factors on raw materials is realized in resonators with magnetrons and frequency generators of pulse-modeled high-frequency oscillations of 110 kHz, where a bactericidal flux lamp serves as a high-potential electrode.Results. Several continuous-flow radiohermetic installations with ultrahigh-frequency (microwave) power supply to non-standard resonators have been developed, inside which a complex effect of a high-intensity electric field, a bactericidal flow of UV rays and ozone is realized to reduce bacterial contamination of the product and neutralize odor during heat treatment of raw materials, the dimensions of which are consistent with the depth of penetration of the wave. Features of conical and biconic resonators − provide radio leakage in continuous operation by cutting off the tip at the level of the critical section, depending on the angle of inclination of the cone generator, and allow you to keep the standing wave inside the resonator. The combination of magnetron and cylindrical resonators increases the efficiency of the interaction of the electron flux with the microwave field, and an increase in the inductive volume, which is a “reservoir” of energy, increases the intrinsic quality of the resonator. A quasi-toroidal resonator, presented as a conical resonator in a toroidal resonator, having small overall dimensions and metal consumption, provides a traveling wave in the annular space, and a standing wave in the conical space. The high electric field strength in the capacitor part of the resonator and the corona discharge in the torus contribute to the disinfection of raw materials.

A high-performance conical-neck helmholtz resonator-based piezoelectric self-powered system for urban transportation

As urbanization accelerates, the issue of traffic noise escalates. Efficiently harnessing this prevalent acoustic energy and facilitating its collection and conversion has emerged as a notable challenge in contemporary research. This paper introduces a piezoelectric self-powered system anchored on a Conical-Neck Helmholtz Resonator-Based Piezoelectric Self-Powered System (CNHR-PSS) which places the piezoelectric device inside a Conical-Neck Helmholtz resonator. This system amalgamates acoustic energy harvesting, traffic noise abatement, and traffic condition discernment. It combines by two parts, including a Piezoelectric Self-Powered Node (PSN) and a machine learning algorithm. The PSN, employing the Conical Neck Helmholtz Resonator and piezoelectric module, seizes noise and transmutes it into electrical energy, showcasing robust scalability. Multiple PSNs coalesce to form a sound barrier for traffic noise mitigation. Concurrently, the voltage signals emanated by the PSN also encapsulate traffic status information. The algorithm extracts feature from the output signal and employs machine learning to decipher traffic conditions. Simulative and theoretical analyses affirm that the system can efficaciously harvest acoustic energy from urban traffic noise and attenuate noise, with a pinnacle output power of 0.52mW and an average noise reduction of 13.16 %. The recognition accuracy of traffic conditions via SVM attained 100 %. The investigative outcomes underscore the exemplary performance of this self-powered system, rendering it a viable solution for applications in traffic noise mitigation and intelligent transportation.

The relationship between the oblique sagittal temporomandibular joint disc position and the volume surface area of the condyle in young TMD adults.

The present study aims to compare the volume surface area of the condyle, the horizontal condylar axial angle and the disc-condyle angle between temporomandibular disorder (TMD) and asymptomatic volunteers, explore and analyze the relationship between the temporomandibular joint (TMJ) disc position in oblique sagittal plane and the volume surface area of the condyle in young adults with TMD symptoms. 84 young adult volunteers were received TMJ examination by Magnetic Resonance Imaging (MRI) and Cone Beam Computed Tomography (CBCT). TMD and asymptomatic volunteers were 42 each. MRI was used to assess the position of TMJ disc in the oblique sagittal plane with the condyle apex method. CBCT data were used for three-dimensional (3D) reconstruction of condyle and the measurements of the horizontal condylar axial angle and the volume surface area of the condyle. The condylar volume surface area of the TMD group was smaller than that of the asymptomatic group (p < 0.05), the disc condyle angle was larger than that of the asymptomatic group (p < 0.05), and no significant difference was found in the horizontal condylar axial angle (p > 0.05). In terms of correlation, the volume surface area of the condyle were negatively correlated with the position of the articular disc in TMD patients (p < 0.05). This significant negative correlation suggests that the possibility of disc displacement can be considered when poor condylar morphology is found.

Diagnostic value of radiological examination methods in the detection of odontogenic sinusitis

It is emphasized that odontogenic sinusitis frequency for at least 9–11% of the total number of inflammatory diseases of the maxillofacial area, and the frequency of their complications ranges from 30% to 50%. Emphasis is placed on the fact that a frequent cause of the development of odontogenic sinusitis is errors in the endodontic treatment of teeth and errors in dental implantation, which is accompanied by the use of tools for processing root canals (root needles, drills, canal fillers, pulp extractors), as well as filling material and an implant behind the apex tooth root into the sinus cavity.&#x0D; Radiological research methods play a leading role in the diagnosis of odontogenic sinusitis. Traditionally, for the evaluation of paranasal sinuses, radiography in the nasolabial projection, inspection radiographs of the skull in direct and lateral projections are used. The advantages and disadvantages of multispiral computed tomography (MCT), magnetic resonance imaging (MRI) and cone beam computed tomography (CBCT) are given separately. For a group of 130 patients, the results of the diagnostic informativeness of radiological examination methods in the detection of odontogenic sinusitis are given.&#x0D; The obtained results allow to conclude that in all cases computer tomography (MCT or CBCT) made it possible to accurately diagnose the form of the disease, determine the extent of sinus damage, assess the condition of the lower bone wall of the sinus (reveal a violation of its integrity and report a tooth socket with a sinus), to determine the center of inflammation in the periodontium, as well as to detect the presence of foreign bodies in the maxillary sinus. At the same time, MCT and CBCT data were fully compared with each other, surpassed traditional radiological methods in terms of diagnostic informativeness and had such advantages as the absence of superposition, high contrast resolution, and the possibility of obtaining higher-quality image reconstructions in different planes.&#x0D; The aim of study. To analyze the diagnostic value of radiological examination methods in the detection of odontogenic sinusitis.Material and methods: We examined 130 patients in the period from 2022 to 2023. X-ray examinations were performed on a Planmeca ProMax 3D cone beam computed tomography scanner and MCT.Results: Regarding the data of СBCT, it is possible to specify the localization of the foreign body and its connection with the odontogenic factor with high probability. It is worth noting that these sinusitis belong to the iatrogenic group of diseases.Conclusions: CT methods (MCT or CBCT) are a necessary component of the complex diagnosis of odontogenic sinusitis.

Jawbone measurements of edentulous sites related to implant planning using magnetic resonance imaging compared to cone beam computed tomography: An exvivo study.

To compare measurements on images obtained by magnetic resonance imaging (MRI) and cone beam CT (CBCT) for height, width, and area in alveolar bone sites in human jaw specimens. Forty edentulous alveolar posterior sites in human cadaver specimens were imaged using CBCT scanners, and with zero-echo-time MRI (ZTE-MRI). Semi-automatic volume registration was performed to generate representative coronal sections of the sites related to implant planning. ZTE-MRI sections were also presented after grayscale inversion (INV MRI). Three observers measured bone height, bone width 5 mm from the alveolar crest, and bone area stretching from the width measurement to the top of the alveolar crest in the images. Interobserver agreement was assessed by intra-class correlation coefficients (ICC). The measurements were analyzed using two-way repeated measures ANOVA factoring observer and image type. ICC was >0.95 for bone height, width, and bone area. No significant differences among observers (p = 0.14) or image type (p = 0.60) were found for bone height. For bone width, observer (p = 0.14) was not a significant factor, while ZTE-MRI produced width estimates that were significantly different and systematically smaller than CBCT-based estimates (p ≤ 0.001). Observer (p = 0.06) was not a significant factor regarding the bone area measurements, contrary to the imaging type where ZTE-MRI led to significantly smaller area estimates than CBCT (p ≤ 0.001). Bone height measurements were essentially equivalent using CBCT and MRI. This was found regardless of grayscale choice for the MRI. However, ZTE-MRI resulted in smaller estimates of bone width and area.

Magnetic Resonance Imaging and Cone Beam Computed Tomography Evaluated Stafne Bone Cavity: Report of Two Cases

Magnetic Resonance Imaging and Cone Beam Computed Tomography Evaluated Stafne Bone Cavity: Report of Two Cases

Resonance cones in cold plasma: Origin, singularities, and power flow

In magnetized tenuous plasma, typical at the plasma edge of fusion devices, a nearly electrostatic wave mode with relatively enhanced electric field can propagate along a specific angle with the magnetic field. For this characteristic, it is known as a “resonance cone.” For instance, these waves can be excited by radio frequency antennas in the ion-cyclotron and lower-hybrid range of frequencies. We consider the resonance cones emitted by idealized spatially extended sources. In 2D, we use a novel geometric construction which generalizes the d'Alembert solution to curved boundaries/moving sources, and show, for the first time, that singular electric fields arise under these conditions, thereby bringing the resonance cones in line with the other resonances of the cold plasma theory. Still in 2D, we give an expression for the amount of power radiated by resonance cones in terms of surface quantities on the source, which is finite despite the singular electric field. We generalize the conclusions regarding the presence and location of singular electric fields to the 3D electromagnetic case.

Resolution of a Few Problems in the Application of Quasilinear Theory to Calculating Diffusion Coefficients in Heliophysics

AbstractA theory of quasilinear diffusion for obliquely propagating electromagnetic waves was developed in the 1960's and applied in the 1970's to model scattering of relativistic electrons by a prescribed distribution of waves. In the latter work, a transformation of variables, from wavevector space to the temporal frequency and tangent of the wave normal angle, was used so that simple Gaussian functions of frequency and tangent of the wave normal angle could be multiplied together to define the distribution of wave power, although arbitrary distributions of power in these two variables is also permitted. Finally, in 2005, previous work was consolidated and has been widely used in heliophysics studies that require computation of quasilinear diffusion coefficients. Here it is shown that this transformation is inppropriate when the precise wave vector distribution is known. The correct transformation is derived and used to produce diffusion coefficients that can differ by orders of magnitude from those computed using the inappropriate transformation. The differences are largest when the distribution of wave power extends to wave normal angles near the resonance cone. When the ratio of the plasma frequency to the gyrofrequency is large, only low energies (keV) are affected, but as the ratio decreases higher energies (MeV) also show differences. It is also shown that the derivation from the 1960's uses a notation that results in the diffusion coefficients depending on the distribution of wave power with respect to the wave azimuthal angle whereas there should be no such dependence.

Numerical investigations on energy conversion performances in twin standing-wave thermoacoustic engines with various geometric and operational conditions

The present work considers the heat-driven acoustic characteristics and dynamic thermal-fluid flow fields in a twin standing-wave thermoacoustic engine (TSWTAE). Emphasis is placed on enhancing its acoustic power output performances for efficiently driving thermoacoustic refrigerators by varying operating conditions and geometric shapes. For this, a time-domain 2D twin TAE model is developed to analyze the TSWTAE in the presence of different working gases and various operating pressures first. It is then applied to examine the geometry effect on the thermo-acoustics energy conversion performances of the twin SWTAE. The model is validated by comparing with those results obtained from DeltaEC (Design Environment for Low-amplitude ThermoAcoustic Energy Conversion) software and experimental data available in the literature. The results indicate that the acoustic oscillation pressure and sound pressure level are increased with the charge pressure and the molecular weight of the working gases, while the acoustic power and thermo-acoustics energy conversion efficiency of the different working gases remain roughly constant. Considering the comprehensive acoustic characteristics, the optimal engine performance is achieved with a 0.6 MPa charge pressure, as helium is applied. Furthermore, the implementation of the tapered conical resonator demonstrates a substantial enhancement in oscillation pressure and thermal efficiency, yielding improvements of 82.03% and 32.60% respectively compared to the utilization of a cylindrical narrow resonator in the experimental setup. The present study provides a design tool for predicting and optimizing twin SWTAE performances.

A 3D reconstruction imaging study of the effect of anterior disk displacement on the bony structural relationship of the temporomandibular joint

ABSTRACT Background: The objective of this study was to measure the association between the status of anterior disk displacement (ADD) and the alterations of the mandibular condyle and articular fossa among patients diagnosed with temporomandibular joint (TMJ) ADD. Patients and Methods: A retrospective cross sectional study was designed, dividing into 4 groups: normal articular disk position (NADP) of unilateral ADD patients (n = 10), ADD with reduction (ADDwR, n = 16), ADD without reduction (ADDwoR, n = 24), and healthy volunteers (HV, n = 30) based on magnetic resonance imaging and cone beam computed tomography. After morphological parameters were calculated from three dimensional reconstructive images, differences in parameters with respect to TMJ ADD status were tested with analysis of variance and Fisher's least significant difference multiple comparisons were performed. Results: Patients were with a female to male ratio of 6.75:1 (21 females, 4 males) and an average age of 29.10 ± 8.94 years (ranging from 16 to 51). Condylar volume (CV) of the ADDwR, ADDwoR, NADP, and HVs was 1768.29 ± 404.19 mm, 1467.13 ± 438.20 mm, 1814.48 ± 753.60 mm, and 1914.66 ± 476.48 mm, respectively, showing a significant downward trend from healthy disk to a displaced one (P &lt; 0.05). The same trend also found in condylar superficial area (CSA), with the CSA of the ADDwR, ADDwoR, NADP, and HVs, was 842.56 ± 138.78 mm, 748.52 ± 157.42 mm, 842.87 ± 263.00 mm, and 892.73 ± 164.19 mm, respectively. From NADP to ADDwR to ADDwoR, superior joint space (SJS) was declined (SJS [NADP] [2.10 ± 0.91 mm] &gt; SJS (ADDwR) [1.85 ± 0.61 mm] &gt; SJS [ADDwoR] [1.50 ± 0.50 mm], P = 0.034); medial joint space (MJS) was significantly associated with the different disk displacement types (P [HV ADDwR] = 0.001; P [HV ADDwoR] = 0.021; P [NADP ADDwR] = 0.022; P [ADDwR ADDwoR] = 0.001). Conclusion: The CV and superficial area and superior and MJS are significantly associated with different disk displacement types. The mandibular condyle and articular fossa in TMJ ADD exhibited altered dimensions. These could be promising biometric markers for assessing ADD.

Imaging Techniques for Assessment of Cranio-maxillofacial Complications of Covid-19, A Systematic Review

Objectives: The aim of this review was to summarize and describe the reported imaging techniques used for COVID-19 patients who have developed cranio-maxillofacial complications. Methods: A systematic review of the literature was conducted using MEDLINE/PubMed, Google Scholar, and Scopus databases. Included articles were case reports/series, clinical trials and cross-sectional studies on adult COVID-19 patients that were written in English. Excluded articles were those discussing the radiological assessment of COVID-19 complications manifested in the oral mucosa or the extra-maxillofacial areas. Combinations of the following keywords were used: “COVID-19”, “Maxillofacial,” “complications,” “imaging,” “radiological,” “Mandible,” “Jaw,” “Osteonecrosis,” “cavernous sinus thrombosis,” and “mucormycosis.” Results: A total of 13 articles were included. Imaging techniques used were: magnetic resonance imaging (MRI), computerized tomography (CT), multislice CT (MSCT), contrast-enhanced MRI, contrast-enhanced CT, and cone beam CT. These imaging techniques were used in the diagnosis of craniomaxillofacial complications of COVID-19, including sinusitis, cavernous sinus thrombosis, jaw osteomyelitis, cellulitis, vision loss, and mucormycosis. CT and its variants were the most commonly used techniques. Conclusion: Within the limitations of the included studies, which were mainly case reports, it can be concluded that imaging techniques that were employed in the diagnosis of craniomaxillofacial complications of COVID-19 were limited to MRI, CT and their variants. Despite the efficiency of the utilized imaging techniques, clinicians worldwide should be aware of the most effective and least risk-associated methods used in such circumstances.

Precipitation Rates of Electrons Interacting With Lower‐Band Chorus Emissions in the Inner Magnetosphere

AbstractElectrons trapped in the Earth's magnetic field can be scattered by whistler mode chorus emissions and precipitate into the Earth's upper atmosphere. Whistler mode chorus waves propagating in the Earth's inner magnetic field are usually observed with oblique wave normal angles (WNAs). In this study, we apply 12 chorus wave models with four various WNA sets (the maximum WNA are 0°, 20°, 60°, and 90% of resonance cone angles) and three wave amplitude sets (the maximum wave magnetic fields are 2.1 nT, 307 pT, and 49.4 pT) at L = 4.5. We use test‐particle simulations to trace electrons interacting with the waves and create Green's function sets for electrons initially at kinetic energies (K) 10–6,000 keV and equatorial pitch angles (α) 5°–89°. The simulation results show that in the 2.1 nT cases, the very oblique chorus waves contribute to more electron precipitation than the other three chorus wave models, especially at energies 50–100 keV. Checking the highest initial equatorial pitch angle of the precipitated electrons, we find that the very oblique chorus waves can precipitate electrons with α &gt; 45°. In contrast, the other chorus waves can only precipitate electrons with α &lt; 30°. Furthermore, the precipitation rates reveal that the anomalous trapping effect, which moves low equatorial pitch angle electrons away from the loss cone, in the oblique cases is much weaker than in the parallel case, resulting in higher precipitation rates. Finally, we derive the pitch angle scattering rates and verify the precipitation by nth cyclotron resonances with oblique chorus.

Characteristics of Boomerang Whistler‐Mode Waves Emitted From the DSX Spacecraft

AbstractThe Air Force Research Laboratory's Demonstration and Science Experiments (DSX) spacecraft carried a high‐voltage very low frequency transmitter and a sensitive broadband receiver to medium Earth orbit in 2019. During many pulsed transmission experiments, DSX detected apparent “boomerang” echoes when its emitted waves refracted in the magnetosphere and returned to the spacecraft. We simulated a series of these detected pulses using cold plasma ray tracing to characterize their likely wavelengths, indices of refraction, and initial wave normal angles. The waves were shown to remain relatively local to DSX, to be lightly damped, and to have a wide variety of wavelengths and indices of refraction, but they were all emitted with very oblique wave normal angles tightly clustered about half a degree from the Gendrin angle, which theoretical antenna models predict is preferentially excited. Our results are remarkably consistent with this prediction but are statistically biased closer to the resonance cone, possibly because of limitations in the ray tracing technique. The result is robust to perturbations of the simulation and confirms a very narrow beam of oblique radiation quite unlike the behavior of a dipole in vacuo.

Is magnetic resonance imaging or cone beam computed tomography alone adequate for the radiological diagnosis of symptomatic temporomandibular joint osteoarthritis? A retrospective study

This study was performed to compare the diagnostic accuracy of cone beam computed tomography (CBCT) alone and magnetic resonance imaging (MRI) alone in patients with clinical symptoms of temporomandibular joint osteoarthritis (TMJ-OA). Fifty-two patients (83 joints) with clinical signs of TMJ-OA were included in the study. Two examiners evaluated CBCT and MRI images. McNemar and kappa tests and Spearman’s correlation analysis were applied. Radiological findings of TMJ-OA were detected in all 83 joints on CBCT or MRI . Seventy-four joints (89.2%) were positive for degenerative osseous changes on CBCT. MRI findings were positive in 50 joints (60.2%). Osseous changes were found in 22 joints, joint effusion in 30 joints, and disc perforation/degeneration in 11 joints on MRI. CBCT was more sensitive than MRI in detecting condylar erosion (P = 0.001), osteophyte (P = 0.001), and flattening (P = 0.002) and flattening of the articular eminence (P = 0.013) . Poor agreement (κ = −0.21) and weak correlations were found between CBCT and MRI. The study findings suggest that CBCT is superior to MRI in evaluating osseous changes of TMJ-OA, and that CBCT is more sensitive than MRI in detecting condylar erosion, condylar osteophyte, and flattening of the condyle and articular eminence.

Technological process scheme of the three-stage microwave convection hop drying

At a temperature of 110 ° C, the concentration of alpha-acid reaches 67.5%, beta-acid - 59%, which reduces the consumer properties of hops. The aim of the study is to develop a microwave convective hop dry-er, which provides a process flow rate of less than 0.5 to equalize the mois-ture content of hops in the structure during transportation through a toroi-dal resonator. We used the programs CST Microwave Studio 2018, Com-pass 3D V20. The hop dryer contains two truncated conical and toroidal resonators. In the central cylinder of the toroidal resonator there is no EMPSWH, here the moisture in the hop cones is equalized. In the capacitor part of the resonator, the electric field strength is sufficient to reduce the bacterial contamination of hops. A dielectric grid electric drive conveyor and a perforated ceramic trough are laid along all resonators. The techno-logical scheme of the process provides for determining the amount of evaporated moisture from each resonator, air flow, and the required power of heat guns. The electrical circuit provides control of three magnetrons and a conveyor. The expected specific heat consumption is 3.54 MJ/kg. The total air consumption is 300 m3/h, with a hop dryer capacity of 100 kg/h.

In‐Plane Hyperbolic Phonon‐Polaritons in van der Waals Nanocrystals

AbstractAnisotropic hyperbolic phonon‐polaritons (HPhPs) in a van der Waals material, orthorhombic‐phase molybdenum trioxide (α‐MoO3), provide strategies in multiple dimensions to manipulate photons at the nanoscale. However, the nano‐imaging studies of the in‐plane HPhPs along orthogonal crystal orientations are still rare. In this work, the launching and propagating properties of HPhPs are studied in α‐MoO3 upon a holey silicon nitride microcavity through a photon‐induced force microscope (PiFM) over a broad tunable mid‐infrared region of 780–1010 cm−1. Near‐field patterns stemming from the orthogonal polariton momenta are observed in this spectral band. A simple model based on the geometrical optics of elliptic resonance cones is used to explain the near‐field phonon‐polariton features. These near‐field optical properties indicate abundantly possible operations and applications for nanophotonics.

Quasi-longitudinal propagation of nonlinear whistlers with steep electrostatic fluctuations

The quasi-longitudinal whistlers are recently reported in magnetized laboratory plasmas, i.e., at densities considerably higher than the space or magnetospheric plasmas. Given their oblique nature, these whistlers are known to be accompanied by density perturbations which undergo strong nonlinear steepening exclusively for their propagation close to resonant cone angle [Yoon et al., J. Geophys. Res. 119, 1851 (2014)]. This aspect is examined in the parameter regime of laboratory experiments where quasi-longitudinal whistler fluctuations are reported. A systematic study by a set of dedicated single mode numerical solution of the fully nonlinear model of quasi-longitudinally propagating whistlers is presented predominantly covering the high-density (low magnetic field) regime relevant to the laboratory whistler experiments. Following the recovery of existing computational results available for low-density cases, the computations in the newer regime are performed in the present study. The evolution recovered in both these regimes finds the sharp density structures or oscillations to be of resonant origin. While structures accompanying the whistlers' low-density resonant cone readily agree with the upper hybrid resonance frequency, the freshly covered high-density regime shows that the strong nonlinear nature of the whistler is capable of producing a modification in the resonant frequency, causing it to downshift from its linearly expected upper hybrid frequency.