Resonant Chamber Research Articles

AcousTac: Tactile Sensing with Acoustic Resonance for Electronics-Free Soft Skin.

Sound is a rich information medium that transmits through air; people communicate through speech and can even discern material through tapping and listening. To capture frequencies in the human hearing range, commercial microphones typically have a sampling rate of over 40 kHz. These accessible acoustic technologies are not yet widely adopted for the explicit purpose of giving robots a sense of touch. Some researchers have used sound to sense tactile information, both monitoring ambient soundscape and with embedded speakers and microphones to measure sounds within structures. However, these options commonly do not provide a direct measure of steady state force or require electronics integrated somewhere near the contact location. In this work, we present AcousTac, an acoustic tactile sensor for electronics-free, force-sensitive soft skin. Compliant silicone caps and plastic tubes compose the resonant chambers that emit pneumatic-driven sound measurable with a conventional off-board microphone. The resulting frequency changes depend on the external loads on the compliant endcaps. The compliant cap vibrates with the resonant pressure waves and is a nonidealized boundary condition, initially producing a nonmonotonic force response. We characterize two solutions-adding a distal hole and mass to the cap-resulting in monotonic and nonhysteretic force readings with this technology. We can tune each AcousTac taxel to specific force and frequency ranges, based on geometric parameters including tube length, and thus uniquely sense each taxel simultaneously in an array. We demonstrate AcousTac's functionality on two robotic systems: a 4-taxel array and a 3-taxel astrictive gripper. Simple to implement with off-the-shelf parts, AcousTac is a promising concept for force sensing on soft robotic surfaces, especially in situations where electronics near the contact are not suitable. Equipping robots with tactile sensing and soft skin provides them with a sense of touch and the ability to safely interact with their surroundings.

Exploring and validating heating dynamics in a radio-frequency electromagnetic field-based resonant chamber for mouse hyperthermia research

ABSTRACT Mild whole-body hyperthermia has been shown to have anti-tumor effects through an immune-modulating mechanism. Before it is widely applied in the clinic, tremendous mechanistic research in animals is necessary to adhere to evidence-based principles. The radio frequency electromagnetic field (RF-EMF) based heating facility could be a good choice for hyperthermia treatment, but the heating characteristics of a facility, including structure design, electromagnetic and thermal dosimetry, and the biologic effects of hyperthermia, need to be well elucidated. Here, we reported the heating characteristic study on a resonant chamber (RC) excited by a 1800 MHz solid source. The EMF in the RC was stirred by 24 static reflectors, which resulted in the standard deviation of electric field intensity being below 3 dB in the EM homogeneity evaluation. For the exposure scenario, six free-moving mice were loaded into separate cases and exposed simultaneously in the RC. The EMF energy absorption and distribution in exposed mice were calculated with the 12-plane-waves method of numerical simulation. Different levels of core body temperature increment in exposed mice were achieved through regulation of the source output power. Overexpression of heat shock proteins (HSPs) was detected in the liver, lung and muscle, but not in the brain of the exposed mice. The levels of representative inflammatory cytokines in the serum, TNF-α and IL-10 increased post RC exposure. Based on the heating characteristic study and validation, the applied RC would be a qualified heating system for mild whole-body hyperthermia effect research in mice.

Shannon Theory for Wireless Communication in a Resonant Chamber

Shannon Theory for Wireless Communication in a Resonant Chamber

Tympanal ears mediate male-male competition, courtship and mating success in Bicyclus anynana butterflies.

The presence of intra-specific acoustic communication in diurnal butterflies is not well established. Here, we examined the function of the tympanal ear (Vogel's organ, VO) in the seasonally polyphenic butterfly Bicyclus anynana in the context of sexual signalling. We investigated how the VO and the flanking enlarged veins, which are suggested sound resonance chambers, scale with wing size across sexes and seasonal forms, and how disruptions to the VO alter courtship behaviour and mating outcomes. We found that males have VOs similar in size to females despite having smaller wings, and dry season (DS) male cubital and anal veins do not scale with the wing size. This suggests that the VO plays an important role in males and that cubital and anal veins in DS males may be tuned to amplify specific sound frequencies. Behavioural assays performed with deafened and hearing males of different seasonal forms, in pair and triad settings, showed that deafened DS males, but not wet season males, experienced lower mating success relative to their hearing counterparts. Our study documents a novel function for the wing tympanal membrane in mediating courtship and mating outcomes in diurnal butterflies.

Microwave electrothermal thruster with surface wave plasma

AbstractA new microwave electrothermal thruster (MET) with small dimensions (length of 25 mm and diameter of 6 mm), utilizing surface wave (SW) plasma at low average power consumption Pav ˜ 2 W, is made. It uses microwaves at a frequency of 2.45 GHz for plasma generation within a dielectric chamber enclosed in a metal shield. The SW is excited at the plasma‐dielectric interface by a coaxial launcher and a standing wave is created due to the wave reflection from the shield. The high‐density plasma produced in this resonant chamber heats up the argon gas, which expands through the nozzle in the axial direction. The temperature of the gas decreases from 1900 K at atmospheric pressure to 1200 K at 10 Torr ambient pressure. This small‐sized MET shows stable low‐pressure operation with a thrust of 4 mN and an efficiency of 8% and is suitable for nanosatellite orbit control.

Performance of Resonant Chambers in Oscillating Water Column Devices

The utilization of marine power potential in Colombia holds a great promise, and the oscillating water column (OWC) is one option that deserves to be explored. The wave energy conversion process using an OWC typically involves two stages: the conversion of wave power to pneumatic power in an air chamber, and the conversion of pneumatic power to electricity using a selfrectifying air turbine coupled to an electric generator. In order to improve the efficiency of the primary stage, this study is aiming at determining the hydrodynamic performance of an OWC air chamber using a numerical model based on the Reynolds Averaged Navier-Stokes equations and the Volume of Fluid approach for free surface simulation. The chamber geometry was based on a U-shaped OWC. The maximum efficiency and the mean velocity of the chamber free surface were found to be 66.8% and 0.17 m/s, respectively. The numerical results for the wave height obtained through simulation were validated by comparing them to analytical expressions reported in the existing literature, and a significant level of agreement was observed. Optimizing the chamber shape parameters for the specific wave characteristics is concluded to be crucial to enhance the operating efficiency of the OWC.

Influence of the Electrical Characteristics of Pulsed Microwave Magnetron Power Supply on the Conditions for Plasma Formation in the Vacuum Chamber of Resonator-Type Plasmatron

The paper presents the research results of the influence of the electrical characteristics of a pulsed microwave magnetron power supply on the microwave discharge generation conditions, determined by the operating mode of the generating system as a whole. Plasma was formed in a vacuumized reaction-discharge volume located inside a rectangular resonator chamber. Depending on the operating modes of the microwave magnetron power supply, studies have been conducted for three modes of microwave discharge plasma generation: pulsed mode with a duty factor S ≈ 2; pulsed mode with a duty factor S ≈ 1.15; continuous mode. Probe measurements of the microwave power in the microwave discharge plasma volume and its local conductivity have been carried out. The paper presents the dependence of the power of microwave energy in the central area of the reaction-discharge quartz chamber of a microwave plasmotron on the amount of power consumed by the microwave magnetron, as well as the distribution of the electrical component of the microwave discharge plasma along the length and cross-sectional plane of the working volume. It has been established that for all studied modes of operation of the power source, with an increase in the power consumption of the microwave generator system, an increase in the microwave power recorded in the central region of the plasma discharge is characteristic. The continuous generation mode is characterized by a decrease in the uneven distribution of electromagnetic energy along the axis of the discharge chamber. It is shown that the transition from a pulsed to a continuous mode of microwave plasma discharge generation at the same level of power consumption by the generating system is characterized by a decrease in the value of the registered microwave power in the microwave discharge plasma volume and an increase in its local conductivity in particular areas of the reaction-discharge volume.

Hydrodynamic behavior of resonant chamber of an oscillating column of water for Pacific Ocean conditions

Hydrodynamic behavior of resonant chamber of an oscillating column of water for Pacific Ocean conditions

Optimization of the design of an oscillating water column for the Pacific Ocean conditions using the response surface methodology

Wave energy possesses a significant potential as a sustainable and renewable source of power due to its abundant presence in the Earth’s oceans. This research focused on the assessment of the hydrodynamic efficiency (ɛ) of a resonant chamber within an OWC (oscillating water column) system. Four geometric design parameters of the resonant chamber (h1/h, b2/h, d/b2 and α) were selected to optimize ɛ, being h the depth of the water; h1 and α correspond to the vertical length and angle of inclination of the front wall, respectively; b2 is the width of the resonant chamber, and d represents the diameter of the air outlet hole. To analyze the system, a combined approach utilizing CFD with the VoF (volume of fluid) method and the response surface methodology (RSM) was adopted. The RSM employed a FCCD (face-centered central composite design) to optimize the factors, while the VoF method enabled to simulate in a detailed way the fluid behavior. The ANSYS-Fluent software was employed to perform a transient simulation. A second-order regression model was constructed and validated based on the simulation results. The quadratic regression model exhibited a high Radj2 value (82.81%) and had a p-value associated ¡0.05 (4.66 × 10-8). Therefore, the model was highly significant in accurately representing the ɛ of the OWC resonant chamber. The highest ɛ value (67.01%) was obtained for h1/h, b2/h , d/b2 and α equal to 0.7786, 0.4455, 0.0863, and 89.38°, respectively. The numerical results were validated with the Stokes second-order wave theory and a good correlation was observed with the numerical findings. This study demonstrates that the designed and optimized OWC can be effectively utilized in the Colombian Pacific Ocean to generate electrical energy, promoting economic development in the area.

3-D polarization insensitive ultrawideband frequency selective rasorber with switchable transmission band

A novel polarization insensitive ultrawideband frequency selective rasorber (FSR) based on a 3-D cubic structure is proposed, and the fundamental operating principles of the three parts are demonstrated by equivalent circuit models. The first one is a 3-D FSR based on the multiple resonant absorptions of the curved longer dipole and shorter dipole excitation in the resonance chamber and the insertion of the interdigital resonator (IR) structure in the shorter dipole to form a transmission window. The passband with an insertion loss of less than 3 dB is 10.3–12.9 GHz (22.4%), and the frequency bandwidth with a reflection coefficient of less than −10 dB ranges from 4.2 to 20.5 GHz (132%). The second is a reconfigurable frequency selective surface (FSS) with two operating states, and the third is a 3-D FSR with a switchable passband feature that incorporates the above two structures of loaded switching diodes.

Highly sensitive trace gas detection based on a miniaturized 3D-printed Y-type resonant photoacoustic cell.

We report, what we believe to be, a novel miniaturized 3D-printed Y-type resonant photoacoustic cell (YRPAC) consisting of a frustum of cone-type buffer chamber and a cylindrical resonant chamber. The volume of the designed YRPAC is about 7.0 cm3, which is only about a half of the T-resonant photoacoustic cell (TRPAC). The finite element simulation of the sound field distribution of the TRPAC and YRPAC based on COMSOL shows that the photoacoustic signal is enhanced with the shape of the buffer chamber changing from the traditional cylinder to a frustum of cone. The photoacoustic spectroscopy (PAS) system, utilizing the YRPAC and TRPAC as the photoacoustic reaction units, a 1653.7 nm distributed feedback (DFB) laser as the excitation light source, a cantilever beam acoustic sensor as the acoustic sensing unit, and a high-speed spectrometer as the demodulation unit, has been successfully developed for high-sensitivity trace CH4 sensing. When the CH4 concentration is 1000 ppm, the 2f signal of YRPAC in the first-order resonance mode is 2.3 nm, which is 1.7 times higher than the 2f signal amplitude of TRPAC. The detection sensitivity and minimum detection limit for the PAS system are 2.29 pm/ppm and 52.8 parts per billion (ppb) at 100 s of averaging time. The reported YRPAC has higher sensitivity, smaller size, and faster response time compared to the conventional TRPAC, which can provide a new solution for PAS development.

“Do ye Sweep the Lyre?”: Romantic Resonances in The Poems of Ossian

ABSTRACT James Macpherson’s The Poems of Ossian establishes an elegiac bardic voice that emerges out of the Ossian poems and was especially inspirational for Romantic writers. Fragments of Ancient Poetry (1760) contains not only an epic bardic voice, but, more importantly, the echoing melancholic voice of the elegy. My reading of The Poems of Ossian as a polyphonic text in which the elegiac voices join the songs of the epic bard helps us to reimagine texts influenced by Ossian, and thus Romanticism itself, as a kind of resonant echo chamber in which elegiac mourners emerge and simultaneously speak to the past and to the future. I bring these readings to bear on a text directly responding to Anne Bannerman’s sonnet “From Ossian” (1807). By reading Ossian’s elegiac voice in the context of works which participate in the burgeoning Romantic tradition, I uncover an alternate literary history which embraces necessary fragmentation, a chorus of voices both alive and dead, a prophetic voice shrouded in uncertainty, and an ambivalent relationship with gender as integral to Romanticism writ large. Interpreting the powerfully hybrid elegiac voices in Ossian identifies a new lineage in Romanticism in which the elegy emerges as a dominant form.

Numerical and Experimental Analysis of Pressure Pulsation Attenuator Based on Helmholtz Resonator

Due to the development of aviation hydraulic systems towards high pressure and high flow, the frequency range of pressure pulsation becomes wider, and the amplitude of pulsation increases. This puts higher requirements on the attenuation characteristics of the pressure pulsation attenuator. To reduce the damage caused by pressure pulsation to the pipeline, a Helmholtz-type pulsation attenuator (HTPA) is designed, which works through the Helmholtz resonant chamber. The theoretical model of HTPA is established by the method of lumped parameter method and distribution parametric method. The insertion loss is adopted to evaluate its attenuation characteristics. The internal pressure dynamic characteristics and attenuation effect of the HTPA are analyzed by simulation and experimentation. The results show that the pulsation attenuation rate δ was 40% after the installation of the attenuator. In the frequency range of 0–1000 Hz, the maximum insertion loss is 19 dB, which verifies the validity and correctness of the theoretical model.

Experimental and theoretical determination of the speed of sound in lung parenchyma of rabbits

The purpose of the study was to develop an experimental-theoretical method for determining the speed of sound in the lung parenchyma. The method is based on the measurement of the characteristics of the impedance of the Helmholtz resonator, that contains lungs under study. The input impedance of the Helmholtz resonator corresponds to the parallel connection of the lung impedance and a resonator. The modified two-microphone method is used to measure the resonant frequency and input impedance response of the product of the resonator chamber volume (lungs). The experimental system consisted of a loud speaker, a wave guide, two microphones for the measurement, and the end empedance node in the form of a connecting tube extended to the inside of the Helmholtz resonator with specified geometric characteristics. When the lungs are added to the Helmholtz resonator, the frequency increases, but not linearly with the decrease in their volume, indicating that the speed of sound is abnormal low in the lung parenchyma. The difference between the calculated and measured resonant frequencies is used to determine the speed of sound in the lung parenchyma. The measurements were carried out on air and collapsed lungs of 8 apparently healthy rabbits. Two variants of sound transmission in the lung parenchyma, corresponding to isothermal and adiabatic processes, are considered. The results of measurement and calculation demonstrate that the speed of sound in the lung parenchyma of an apparently healthy rabbit is 21-22 m/s, what is in accord with modern theoretical concepts.

Cavitation Reactor for Pretreatment of Liquid Agricultural Waste

One of the most well-known methods of intensifying the process of anaerobic digestion is the pretreatment of raw materials. For the first time, the use of a jet-driven Helmholtz oscillator for biomass pretreatment is proposed. The design of the device is optimal for creating hydraulic cavitation; however, in this case, acoustic oscillations are generated in the system and resonance occurs. In this study, the optimal design of this device was determined for the subsequent design of a cavitation reactor. The diameter of the resonant chamber was varied in the range from 28.3 to 47.5 mm, and its length from 6 to 14 mm; in addition, the diameter of the outlet was changed from 6.1 to 6.3 mm. Based on the experimental data obtained, it was found that the optimal ratio of the length of the resonator chamber to the diameter of the inlet nozzle is 1.73, and the inner diameter of the resonator chamber to the diameter of the inlet nozzle corresponds to 5.5. Improving the technology of agricultural waste disposal will ensure their maximum involvement in economic circulation, reduce the consumption of traditional fuel and energy resources, and improve the technological and machine-building base, which makes it possible to produce competitive cavitation reactors.

Barrier to Methyl Internal Rotation and Equilibrium Structure of 2-Methylthiophene Determined by Microwave Spectroscopy

The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra of the 34S and 13C isotopologues allowed the determination of the semiexperimental equilibrium structure (reSE). Comparing the structure to that of thiophene revealed a decrease in the ∠(S−C2−C3) angle from 111.595(6)° to 111.37(1)° by addition of the methyl group to the C(2) position, as well as an increase in the S−C2 bond length from 1.7102(1) Å to 1.7219(2) Å. A–E splittings from internal rotation of the methyl group were observed, and the V3 potential in the vibrational ground state was determined to be 197.7324(18) cm−1. The V3 value and the rotational constants A, B, C were calculated with a large number of different methods and basis sets for benchmarking purposes by comparing them to the fitted parameters. The V3 value was also compared to those of other thiophene and furan derivatives to gain a better understanding of the steric and electrostatic effects in these classes of compounds.

Optimization of Ultrasonic Powder Coatings on the Surface of Treated Materials

By generalizing the theory of contact of solids for the case of triple contact of working bodies, the powder particle, the treated surface and the problem of establishing an optimal value for the amplitude of ultrasonic exposure, at which the coating process proceeds most efficiently, were solved. The relevance of such a solution is directly determined by the need to obtain high-quality coating. Analytical expressions of the desired values for the physical parameters of the materials of the objects participating in the working process were obtained. Possible limitations regarding the most important characteristics of the installation were analyzed. Approximate evaluation of the optimal number of working bodies for the resonant chamber was derived. The basic time of the process duration was estimated for the total treatment of the chosen surface by working bodies.

Gandang Tambua Pariaman From Triplek Material an Organological Study Based on Coding

The process of making the Gandang Tamba traditional musical instrument in Padang Pariaman Regency. This study aims to describe the process of making the Gandang Tamba musical instrument. The approach used is a qualitative approach with a descriptive research type. This research was conducted with data collection techniques using observation, interview, and documentation techniques. Data analysis techniques are carried out by reducing, presenting data and verifying data. The aim is to find out the structure, process, manufacturing techniques, and playing techniques, of Gandang Tamba. This musical instrument is made of plywood and has a hole (resonator), and uses goat skin. The results of this study indicate that the parts and stages of the process of making traditional Gandang Tambua musical instruments include: cutting plywood for the body of Gandang Tambua, processing goat skin (membrane), cleaning rattan, making iron battens, and how to produce sound, tuning system on traditional Gandang musical instruments Tambua. The tools used in the process of making traditional Gandang Tambua musical instruments include: Cater knives (plywood cutters), Cutting Saws, Hammers (Penokok), Measuring tools (meters), Pencils, Sandpaper, Screwdriver, Scissors, Bamboo type gutters, and Tongs. The ingredients are; Wooden battens (circle 40), plywood, goat skin, iron lath, rope, nails, and wood glue. The process of making the Gandang Tambua musical instrument includes several stages, namely: 1) The process of making the body (plywood), to the finishing of fine and coarse sanding, 2) The processing of the skin, including the shearing of the skin using dry fuel ash and measuring the width of the diameter, 3) The installation process, includes the skin to the body of the Tambua drum, attaching iron battens and attaching strings as for tuning. The frequency and tension of each instrument membrane on the Gandang Tambua musical instrument, the membrane tension of 141090.66 N on the Gandang Tambua musical instrument produces good tension (tuning), because the vibrations of the membrane will fill the resonance space in the drum tube. While the membrane tension of 131841.38 N produces poor tuning, the vibration of the membrane does not meet the resonance chamber. attach the iron battens and attach the rope for tuning. The frequency and tension of each instrument membrane on the Gandang Tambua musical instrument, the membrane tension of 141090.66 N on the Gandang Tambua musical instrument produces good tension (tuning), because the vibrations of the membrane will fill the resonance space in the drum tube. While the membrane tension of 131841.38 N produces poor tuning, the vibration of the membrane does not meet the resonance chamber. attach the iron battens and attach the rope for tuning. The frequency and tension of each instrument membrane on the Gandang Tambua musical instrument, the membrane tension of 141090.66 N on the Gandang Tambua musical instrument produces good tension (tuning), because the vibrations of the membrane will fill the resonance space in the drum tube. While the membrane tension of 131841.38 N produces poor tuning, the vibration of the membrane does not meet the resonance chamber.

N, S co-doped porous carbon nanosheet foam as MALDI matrix for efficient and direct profiling of biomolecules and environmental contaminants

It is still urgent to develop a powerful method for high-throughput and sensitive analysis of various small biomolecules and environmental contaminants. Herein, a three-dimensional foam consisting of nitrogen and sulfur co-doped porous carbon (N, S-C) nanosheet synthesized was served as an excellent matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) efficiently and directly detecting various small biomolecules and pollutant compounds. This N, S-C nanosheet possessed the advantages of carbon foam for resonant chamber, high-contents of N/S heteroatoms co-doping, large surface area, hierarchical pore and good UV absorption. The use of N, S-C matrix could exhibit higher MS intensities, lower background noise, better salt tolerance and higher sensitivity for probing the various analytes, much superior to the traditional CHCA (α-cyano-4-hydroxycinnamic acid) matrix and control materials (C and N-C). The limit of detection (LOD)s of 1-hydroxy-pyrene, 4-nitrocatechol and nitroguaiacol were calculated to be 0.1 μg/mL, 1 μg/mL and 8 μg/mL at a signal-to-noise ratio (S/N) of 3. Moreover, the rapid and precise detections of 4-nitrocatechol, nitroguaiacol, and 1-hydroxy-pyrene in PM2.5 real sample have also been achieved. Through density functional theory (DFT) simulations, we reveal the sensing mechanism of small molecular deprotonation with the N and S co-doping into carbon matrix. This work may be promising to provide an excellent carbon matrix for the analysis of MALDI-TOF MS method in the biological and environmental field.

Anatomical and Physiological Basis of the Mongolian Khuumii

Objectives: In order to examine each variety of khuumii used by Mongolians, this study compares the anatomical structures involved in the development of khuumii as well as the characteristics and patterns of their functioning.Methods: 50 people between the ages of 18 and 60 were chosen for the cross-sectional study, using a non-random sampling procedure. Statistical analysis was performed using SPSS23 software using questionnaires, X-ray, endoscopy, and acoustic analysis. Results: During the formation of khuumii sound, thoracic cavity, diaphragm, and lungs regulate the intensity of the air reaching the vocal folds, exert pressure on the airways and vibrate the sound waves through air flows passing through the larynx and vocal folds. The mouth-nose cavity as well as the pharynx are responsible for resonating the sound. Khuumii increases the workload of the cardiovascular system by 70-80%. Furthermore, the sound frequency is 2-4 times higher than that of normal speech, and sound volume is 0.5-1 times higher. 95.3% of throat singers do not have a sore throat, 88.4% do not experience heavy breathing, and 74.1% have no hoarseness. Conclusion: The Mongolian throat singing khuumii, including mixed voices and multivoice, iss related to the presence of dual vibration sound sources. Its high overtone form of singing (isgeree khuumii) is related to stenosis at the resonance chambers initiation site (ventricular folds level).