kHz Frequency Research Articles

Structure, Microstructure, and Dielectric Properties of Bi<sub>0.5</sub>(Na<sub>0.78</sub>K<sub>0.22</sub>)<sub>0.5</sub>TiO<sub>3 </sub>Lead-Free Ceramic

In this article, the structural, microstructural, and dielectric properties of Lead- free perovskite ceramic Bi0.5(Na0.78K0.22)0.5TiO3 [BNKT] have been reported. The material was synthesized through the solid-state reaction method. The compound formed is found to have a hexagonal structure, confirmed by XRD analysis of the sample. The microstructural analysis of the compound revealed the polycrystalline nature of the ceramic having quasi-cubic grain morphology with distinct grain boundaries. From the dielectric study, it was found that the dielectric constant increases with temperature and attained maximum value at temperature Tc = 335° C, after which it decreased. The frequency independence of transition temperature (Tc) suggested the classic ferroelectric behaviour of the compound. The broad dielectric peak around transition temperature confirms the relaxor behaviour of the compound as well as diffused phase transition at Tc. The value of the relative permittivity and loss tangent at ambient temperature for 1kHz frequency is 627 and 0.223 respectively. The synthesized material can be utilized for the fabrication of capacitors and energy storage applications.

Study on three-dimensional dielectrophoresis microfluidic chip for separation and enrichment of circulating tumor cells

BackgroundCirculating tumor cells (CTCs) which means tumor cells shed into the peripheral blood of humans, are one of the important indicators in the early and accurate detection of malignancy. ObjectiveThis paper is based on the principle of dielectrophoresis, the design and performance research of microfluidic microarray separating and enriching CTCs was carried out, and the separation and enriching of CTCs was realized by ultilizing the difference in dielectrophoretic force and the movement trajectories between CTCs and leukocytes. ResultsChip structure design and optimization based on the COMSOL software simulation tool, through the separation experiment of human breast cancer cell MCF-7 and white blood cells, 60 kHz was selected as the frequency of cell separation experiment. Taking human liver cancer cell SMMC-7721 and human leukocyte mixture as the research object, the chip separation and enrichment experiment of CTCs was conducted. At 5 V voltage and 60 kHz frequency, the maximum separation flux of three-dimensional dielectrophores is microfluidic chip for human liver cancer cell SMMC-7721 reached 1.1 mL/h, and the separation efficiency was about 94%. ConclusionThe results of this research have important implications for separating, sorting and detecting CTCs.

Comparison of different inversion strategies for electrical impedance tomography (EIT) measurements

SUMMARY Electrical impedance tomography (EIT) is a promising method to image the frequency-dependent complex electrical conductivity distribution of the subsurface in the mHz to kHz frequency range. In contrast to the well-developed electrical resistivity tomography (ERT) method, the inversion approach for EIT data is less established. Different inversion strategies have been proposed, but the implications of the differences between these methods have not been investigated yet. In this study, we aim to compare four different inversion strategies for EIT measurements. The first strategy (CVI) formulates the inverse problem in the complex number domain and is mathematically the most elegant method. The second strategy (RVI) is the established real-valued inversion method, which decouples the inversion of the real and imaginary parts and completely ignores the complex nature. The third strategy (ALT) is very similar to the RVI strategy in case of small phase angles, but it considers the complex coupling in the forward operator and alternately updates the real and imaginary parts of the model in the case of large phase angles. The fourth and final strategy (CVI+) was newly formulated in this study. It fully considers the complex nature of EIT measurements but separates the treatment of the real and imaginary part in terms of the data weighting and regularization. The different inversion strategies were tested with two synthetic models. The first model has a small phase contrast and the second model has a large phase contrast. In the case of a small phase contrast, the CVI strategy was able to resolve the distribution of electrical conductivity amplitude, but the inversion result for the phase angle was less reliable. The other three strategies presented similar results and the models were well resolved within the expected data misfit. In the case of a model with large phase contrast, only the newly formulated CVI + strategy was able to produce reliable results. It was found that the extremely large phase angle can have a significant influence on the modelled amplitude of data. The cross-sensitivity (i.e. the imaginary part of the sensitivity) that describes the influence on the real part of data due to a change in the imaginary part of model, or that on the imaginary part of data due to a change in the real part of model, provided unique information during the inversion. It was concluded that the CVI + strategy is theoretically the most comprehensive and correct approach for EIT inversion, but that in the case of small phase angles the RVI strategy has the practical advantage that no complex calculations are required, which substantially reduces the required computational effort.

Effect of the acoustic manipulation on single phase immersion cooling performance of discretely heated vertical plate

In the cooling of high heat capacity systems, immersion cooling systems are increasing importance due to the insufficient heat dissipation rates of conventional cooling systems. In this study, the effects of ultrasonic sound waves on cooling performance in single-phase immersion cooling systems were investigated. Experimental study was carried out with ultrasonic sound waves for 9.6 kHz, 14.4 kHz, 19.2 kHz, 24 kHz and silent conditions. In addition, the effects of discrete heat sources on thermal performance were investigated by changing the surface (embedded, 2 mm protruding, 4 mm protruding) and location configurations. According to the results obtained, the highest heat transfer coefficient was calculated as 1703.36 W/m2 °C for the embedded heat source closest to the tank bottom for at 24 kHz frequency. The lowest heat transfer coefficient was calculated as 373.28 W/m2 °C for the maximum protrusion amont heat source closest to the tank upper and when ultrasound manipulation was not applied. In addition, the immersion cooling heat transfer coefficient was increased by 107.49% with ultrasonic sound wave. The heat transfer coefficient increased with increasing ultrasound frequency and decreased with increasing protrusion thickness.

Non-invasive Assessment of Cartilage Damage of the Human Knee using Acoustic Emission Monitoring: a Pilot Cadaver Study.

Knee osteoarthritis is currently one of the top causes of disability in older population, a rate that will only increase in the future due to an aging population and the prevalence of obesity. However, objective assessment of treatment outcomes and remote evaluation are still in need of further development. Acoustic emission (AE) monitoring in knee diagnostics has been successfully adopted in the past; however, a wide discrepancy among the adopted AE techniques and analyses exists. This pilot study determined the most suitable metrics to differentiate progressive cartilage damage and the optimal frequency range and placement of AE sensors. Knee AEs were recorded in the 100-450 kHz and 15-200kH frequency ranges from a cadaver specimen in knee flexion/extension. Four stages of artificially inflicted cartilage damage and two sensor positions were investigated. AE events in the lower frequency range and the following parameters provided better distinction between intact and damaged knee: hit amplitude, signal strength, and absolute energy. The medial condyle area of the knee was less prone to artefacts and unsystematic noise. Multiple reopenings of the knee compartment in the process of introducing the damage negatively affected the quality of the measurements. Results may improve AE recording techniques in future cadaveric and clinical studies. This was the first study to evaluate progressive cartilage damage using AEs in a cadaver specimen. The findings of this study encourage further investigation of joint AE monitoring techniques.

Aerodynamic-whistles-based ultrasonic tone generators for bat deterrence

Novel ultrasonic bat deterrents based on aerodynamic whistles are proposed and investigated experimentally and numerically for their ability to generate ultrasound. The baseline deterrent, a single-whistle design inspired by Beeken [“Fluid ultrasonic generator,” U.S. patent 3,432,804 (1969)], is examined first. It consists of two resonating cavities/chambers. The whistle is “powered” by a regulated high-pressure air supply, and the performance of the whistle is examined for a range of supply pressures. Far-field acoustic measurements in the 20 Hz–50 kHz frequency range are made in an anechoic chamber. The noise measurements are supplemented with two- and three-dimensional unsteady Reynolds-averaged Navier–Stokes (uRANS) simulations to investigate the mechanisms of ultrasound generation. The Ffowcs Williams–Hawkings acoustic analogy is used with the three-dimensional uRANS results to predict the far-field radiation. The far-field acoustic predictions are in good agreement with the measurements in the anechoic chamber. The peak frequency (fundamental) of the radiated ultrasound of the baseline deterrent is approximately 23 kHz. Harmonics and a sub-harmonic of the fundamental tone are also observed. The numerical simulations show that the two resonating chambers of the baseline deterrent operate out-of-phase and Helmholtz resonance determines the whistling frequency over the range of supply air pressure considered. A six-whistle deterrent targeting a broad spectral coverage in the 20–50 kHz frequency range is designed, fabricated, and tested in the anechoic chamber. Each whistle in the deterrent is obtained by geometrically scaling the baseline whistle. Measurements show that the six-whistle ultrasound deterrent generates ultrasound with six dominant peaks in the designed frequency range when the supply air pressure exceeds 5 psig. The proposed ultrasound devices can be used for a variety of purposes including bat deterrence at wind turbines.

Plasma-Made Nanogold for DNA Sensing with SERS

Facilitated electrochemical properties of plasma are crucial for improving functional nanomaterials synthesis and design for novel sensor development. Controlled customization and functionality tailoring at multiscale is the targeted challenge for better detection devices performance. In the modern era of optoelectronics, among various probing approaches, plasmonic sensing accompanied by Raman, FTIR or Fluorescent spectroscopy is considered a tool for the efficient investigation of molecular properties. In particular, Raman scattering is often called SERS (surface-enhanced Raman scattering) due to plasmonic enhancers, which are used to improve the probing of analytes at a reduced scale. This feature is extremely useful for biologically relevant analytical tasks when samples alike DNA and similar need to be investigated fast and accurately. DNA/RNA-related investigations are highly important in modern nanomedicine due to the solid progress of bionanotechnology, DNA vaccines, and functional gene engineering. DNA is the most valued substance for microbiologists because it contains information about bio-species' nature.[1] Currently, the number of molecular-sensitive methods for DNA-level study is quite limited, among which PCR (polymer chain reaction) related methods dominate the field. However, it is challenging to investigate it with optical techniques like SERS. Despite being promising, SERS is still under technological and analytical improvement. Better performance comes with sophisticated plasmonic nanomaterials, which provide considerably improved photon scattering due to the strongly localized field confinement effect.[2] In the current report, a well-performing nanoplasmonic sensor was designed using a plasma-driven electrochemical reduction mechanism. Exploiting atmospheric pressure He-plasma jet setup operating kHz frequency, the reactive oxidative species donated electrons via liquid-gas electrochemistry towards the Ar-delivered Au(3+)-containing microdroplets. Through this method, microscaled aggregates composed of AuNPs were obtained from the nebulized ionic gold liquid precursor. Due to the strong coupling between nanoparticles, a high analytical enhancement factor of about 107 was achieved and the substrate allowed to obtain Raman fingerprints of bacterial DNA fragments (M. luteus and S. aureus, E. coli, J. lividum) at nanovolume sample quantities. In addition, main DNA molecular vibrational signatures associated with nucleobase motions were extracted from spectra collected and used to classify the bacterial strains reliably by employing statistical principal component analysis.

Physics Based Temperature Dependent EIS Simulation on 18650 NMC/Graphite Cell

Electrochemical Impedance Spectroscopy (EIS) is a non-destructive method that provides crucial insights regarding the battery processes. EIS is mainly done by applying a small amplitude AC with a 10 mHz to 1 MHz frequency range. One can determine the electrolyte's ohmic resistance, the Solid Electrolyte Interface (SEI) capacitance, electron transfer rate and the diffusion mechanisms at separate frequency regions from each other.One disadvantage of EIS is the ambiguity of the analyses of the data. The equivalent circuit models used are not unique, and the correspondence between the various elements in the equivalent circuits to electrochemical phenomena are suspect. A new approach on EIS analysis is sought after in order to improve the interpretation. For example, distribution of relaxation times (DRT) was proposed by Zhang et al. in 2015 .Using physics-based models in order to model EIS has been published by Murbach and Schwartz in 2018. In their work, they created a physics-based simulation which uses a pseudo two-dimensional battery model. Their main aim was to present a new approach to EIS data analysis by using a physics-based model rather than equivalent circuit models. They created a data set with 38.800 separate spectra and match the experimental data by using least squares matching approach with the previously computed data. Though this work improved the understanding, multiple calculated data sets matched the experiments with similar errors.Ultimately, in order to achieve an EIS analysis method that is directly related to the fundamental parameters regarding the electrochemistry, degeneracies have to be removed via temperature dependence and the non-linearities as extra dependent variables. This way, the ambiguities and the suspicious parameter assigning can be fixed.We will be reporting on T-dependent linear and nonlinear simulations on 18650 NMC/Graphite battery. All the simulations were done on Python by using a physics-based model PyBaMM (Sulzer, Valentin, et al. "Python battery mathematical modelling (PyBaMM)." Journal of Open Research Software 9.1 (2021).). Impedance data was obtained via simulating voltage as a function of current within 100 µHz to 10 kHz frequency range. Temperature range was set to -25°C to 65°C with 10°C increments. The linear and non-linear impedance is analyzed as a function of temperature. Our results will be compared with experimental temperature dependent linear/nonlinear spectra in order to obtain proper fundamental parameters

Comparison of non-reactive flow fields in conventional swirl-air combustion and swirl distributed combustion

Flow field distribution in traditional swirl flow and simulated distributed reaction swirl flow configuration was examined at 3 kHz frequency using high-speed Particle Image Velocimetry (PIV). Non-reactive flow field conditions in distributed reaction zones were fostered from the conventional swirl flow case using the designed inlet mixture preparation with CO2 dilution of the inlet airstream that corresponded to the combustion case at a heat release intensity of 5.72 MW/m3-atm. High-speed imaging of flow fields was performed at a framing rate of 3000 frames/s using a Neodymium-doped Yttrium Lithium Fluoride (Nd:YLF) laser beam at 527 nm wavelength to capture the Mie scattering images of the flow field. Mean flow velocity obtained from the post-processing of raw PIV images showed higher momentum flux injection in the swirl distributed flow zone case as compared to the normal swirl flow case. Enhanced velocity fluctuations were also observed in both the axial and radial direction for the distributed swirl flow case resulting in higher turbulence for the examined condition. The distributed swirl flow case showed a prominent corner recirculation zone along with higher flow entrainment within the recirculation zone. Enhanced interaction of average streamlines with vortices was found in the swirl distributed flow case. Increased turbulent fluctuation in the two different spatial directions was responsible for higher Reynolds stress distribution (u′v′) in the distributed flow case, indicating improved mixing behavior at lower global oxygen concentrations from the carbon dioxide (CO2) dilution, and showed different length scales of turbulent eddies. Furthermore, the spatial local Damkӧhler number values for distributed flow case (for its implication in reacting case) were found to be less than unity. The results showed a shorter flow timescale than the corresponding chemical timescales in distributed reaction zone. These results help support substantiating the difference of reaction regimes on the Borghi diagram (plot of velocity fluctuation/ laminar flame speed versus the integral length scale/ flame thickness) between the distributed reaction zone (that possesses thickened reaction zone) and conventional swirl reaction flow regimes having corrugated flamelet zone.

Very High Cycle Fatigue and Ultrasonic Testing in Multiaxial Loading

Abstract Fatigue damage has special relevance on the lifespan of mechanical components and structures, as it takes responsibility for the majority of registered structural failures. Most fatigue testing today still uses uniaxial loads, nonetheless it is generally recognized that multiaxial stresses occur in many full-scale structures. Nowadays, the growing need for greater lifespans forced the study of material behavior under what is nowadays very high cycle fatigue (VHCF) regime, fatigue research beyond 10E07 up to 10E10 cycles. However, most classic fatigue machines are often very costly, both in terms of time and energy, for such an elevated number of cycles. The high costs of equipment and time to conduct such experiments have seen a massive improvement with the introduction of high frequency ultrasonic machines. Presently, it is already possible to characterize materials VHCF response under axial and multiaxial loading conditions in a fraction of the time. Ultrasonic testing machines were first introduced for simpler uniaxial loading and more recently adapted for multiaxial loading conditions. The present work reviews the current background of ultrasonic fatigue testing machines working at 20-kHz frequency, with emphasis on multiaxial fatigue and VHCF. A review of a series of fatigue tests are presented, respectively, axial, shear, axial/shear, and in-plane bi-axial fatigue tests with different combining dimension specimens allowing different shear/axial stress ratios. Special attention will be put into the performance of multiaxial classical cylindrical specimens under tension/torsion and flat cruciform specimens under in-plane bi-axial testing using low-cost piezoelectric transducers. By comparing all so far developed and successfully reached multiaxial specimens and respective methodologies, two base approaches were possible to be established. When designing new specimens or ultrasonic machines, or both, one of the two methods must be followed. To have a well-comprehended methodology and successful design approach will undoubtedly guide future multiaxial ultrasonic method ideas.

A Correlational Study of Hearing Loss and Severity of Diabetic Retinopathy Among Jordanian Patients.

Background Sensorineural hearing loss (SNHL) is a common complication of diabetes, but the underlying mechanisms and risk factors are not fully understood. This study investigatedthe relationship between several potential risk factors and SNHL in 118 individuals previously diagnosed with diabetes mellitus type 2 (DM2). Methods We did a cross-sectional analysis of data collected from 118 patients with diabetes mellitus at multiple tertiary hospitals in the Jordanian Royal Medical Services (JRMS). The mean age was 60.57 ± 12.8 years, with 56.8% males. Demographic and clinical data were collected, including age, gender, duration of diabetes, presence and duration of hypertension, diabetic retinopathy (DR) severity, tinnitus, and comprehension inability. In addition, a hearing assessment for SNHL was performed using pure-tone audiometry at 0.5, 1, 2, 4, and 8 kHz frequencies. Goodman and Kruskal's γ test and cumulative odds ordinal logistic regression were used to analyze the relationship between these factors and hearing assessment results for SNHL. Results Goodman and Kruskal's γ test showed a statistically significant moderate and positive association between diabetic retinopathy severity and sensorineural hearing loss. Further analysis using logistic regression revealed that retinopathy severity, age, and gender were all significant predictors of hearing loss level in this population. The odds of having a higher level of hearing loss increased by 9.1% for each additional year of age and were higher for males than females. In terms of DRseverity, a worsening SNHL had lower odds in individuals with no DR or mild nonproliferative DR compared to those with proliferative DR. Conclusion Our findings have important implications for managing SNHL in individuals with diabetes. They indicate that healthcare providers must closely monitor and manage therisk factors in patients with diabetes. Further research is needed to generalize better the relationship between these risk factors and SNHL, including the potential role of other factors, such as exposure to loud noise or certain medications.

Laser - Produced Functional Surfaces of Silicon and Quartz

Fiber laser of 1064 nm wavelength was employed for micro/nano machining process of silicon and quartz substrates. The experimental data reveal formation of silicon nanoparticles by pulse laser ablation in liquid. Various characterization techniques were used such as UV-Visible absorption, SEM morphology to examine silicon nanoparticles. Moreover, generation of microbeams from micro lens array was created by direct writing of fiber laser on quartz. Theoretical calculations using COMSOL software were adopted to estimate the surface temperature distribution at silicon and quartz surface and underneath. It is found that maximum temperature of about (4600 K) and (2400 K) for silicon and quartz respectively when 15 W laser power, 127 ns pulse duration, 30 KHz frequency and 100 mm/sec laser speed was used. Potential applications of silicon nanoparticles and microbeams array in optoelectronics and biological imaging can be conducted due to the controllable laser micro/nano machining process.

The VLF-induced ionospheric perturbations detected by DEMETER during solar minimum

The VLF-induced ionospheric heating events from the powerful transmitter NWC are collected at extremely low solar activity years of 2008–2009, and their spatial and temporal distribution features are investigated. The spatial distribution of heating signals exhibits clear north-direction inclination of 2–3°, and covering area within 300 km radius in longitude and latitude. Plasma parameters show the obvious negative correlations between decreasing Ne and increasing Te, and positive correlations of the increasing ion density and ion temperature during the VLF heating time. The ions move upwards to cause the perturbations in ULF electric field due to mathop{V}limits^{rightharpoonup} times mathop{B}limits^{rightharpoonup}. The VLF heating events easily occur at seasons with low plasma density, which illustrates that low plasma environment plays an important role in VLF-induced ionospheric heating. Typical three enhanced VLF signals are obtained, one at 19.8 kHz with the largest amplitude, one at the broadened frequency band of 19.8 ± 300 Hz with one order of amplitude decreasing, and one between 19.5 kHz and lower hybrid frequency with at least two orders of amplitude reductions relative to that at 19.8 kHz but still one order increasing relative to non-heating region. These quasi electrostatic waves during VLF heating may not be from the VLF whistler conversion, but the lightning-whistler waves are enhanced when they pass through the plasma cavity formed during VLF heating process.

Ultra-low temperature sono-assisted CO2 stripping/ carbon-rich solvent regeneration using different ultrasonic frequencies

ABSTRACT Carbon dioxide emission from anthropogenic sources plays a major role in global warming and climate change. Conventional amine-based carbon capture is matured technology that has limitations on high-temperature use imposed by solvent degradation and solvent loss during CO2 stripping/regenerating solvent. The present experimental investigation involves the application of tank-type (bath-type) sonication for CO2 stripping from aqueous carbon-rich 30 wt% MEA solvent in a low temperature-controlled environment, using ultrasonic frequencies of 25 kHz (cavitation-dominant), 360 kHz (streaming-dominant), and 58/132 kHz dual-mode (combined phenomena). The results are analyzed to understand the effects of carbon loading, CO2 stripping efficiency, stripping rate, temperature profile, and energy demand. The stripping rate is higher in the low-temperature range of 6°C to 12°C for all the frequencies due to the sonication effect. In the mid setpoint range of 15°C to 30°C, the CO2 stripping rate is lower due to the combination of sonication and temperature effect, and when the temperatures increase from 40°C to 45°C, the stripping rate increases gradually due to additional temperature effect. A high cyclic capacity of 1.12 mol CO2/kg. was observed for 360 kHz frequency at 12°C. The lowest energy of 3.94 kJ/mol CO2 was achieved for 360 kHz at a setpoint of 12°C. Factors such as sonication frequency, CO2 loading (mol CO2/mol soln.), temperature, and nominal power of ultrasonics play an important role in determining the sensible energy required for CO2 stripping. Specifically, CO2 stripping at the low temperature set point of 6°C and 12°C is found to be promising in all frequencies, indicating that CO2 stripping is primarily promoted by sonication, rather than by temperature.

Analysis of Ultrasonic Vibration-Assisted Ball Burnishing Process on the Tribological Behavior of AISI 316L Cylindrical Specimens.

In this study, we analyzed the effects of vibration assistance, combined with a ball burnishing process, in terms of topology, residual stresses, and tribological properties on 316L shafts. The burnishing variables consisted of the variation of the input force, the number of passes, and the activation of the vibration assistance, which is based on a 40 kHz frequency and 8 μm of vibration amplitude, derived in a screening design of three factors. The results show that the medium-high level of burnishing force, high level of the number of passes, and the activation of the vibration assistance are the best options in order to improve the average roughness, the microstructure, the increase in the compressive residual stresses, and the wear enhancement, besides all variables being significant in the p-value analysis through ANOVA. Statistically, the vibration-assisted ball burnishing improved the average roughness by 2.9%, enlarged the von Mises stress on the surface by 11.5% and enhanced the wear resistance of a 316L shaft and WC-Co ball contact up to 7.3%.

Sensor-Location-Specific Joint Acquisition of Peripheral Artery Bioimpedance and Photoplethysmogram for Wearable Applications.

Cardiovascular diseases (CVDs), being the culprit for one-third of deaths globally, constitute a challenge for biomedical instrumentation development, especially for early disease detection. Pulsating arterial blood flow, providing access to cardiac-related parameters, involves the whole body. Unobtrusive and continuous acquisition of electrical bioimpedance (EBI) and photoplethysmography (PPG) constitute important techniques for monitoring the peripheral arteries, requiring novel approaches and clever means. In this work, five peripheral arteries were selected for EBI and PPG signal acquisition. The acquisition sites were evaluated based on the signal morphological parameters. A small-data-based deep learning model, which increases the data by dividing them into cardiac periods, was proposed to evaluate the continuity of the signals. The highest sensitivity of EBI was gained for the carotid artery (0.86%), three times higher than that for the next best, the posterior tibial artery (0.27%). The excitation signal parameters affect the measured EBI, confirming the suitability of classical 100 kHz frequency (average probability of 52.35%). The continuity evaluation of the EBI signals confirmed the advantage of the carotid artery (59.4%), while the posterior tibial artery (49.26%) surpasses the radial artery (48.17%). The PPG signal, conversely, commends the location of the posterior tibial artery (97.87%). The peripheral arteries are highly suitable for non-invasive EBI and PPG signal acquisition. The posterior tibial artery constitutes a candidate for the joint acquisition of EBI and PPG signals in sensor-fusion-based wearable devices-an important finding of this research.

Investigation of the behaviour of gold mesh electrodes in electrically controllable membrane electrode assemblies

Hydrogen fuel cell technology is one of the key focus areas to facilitate the transition from carbon-based fuels to more sustainable solutions in the transportation and mobile power sectors. Transient voltage fluctuations due to load changes and even operation of fuel cells with DC/DC and DC/AC converters are detrimental to the lifetime and this paper proposes a method to deal with these fluctuations. Adding electric field modifier (EFM) electrodes made of gold to the membrane of a fuel cell was proposed elsewhere as a way to influence the short term flux of charge carriers through the membrane. While electrochemical impedance spectroscopy shows a limited capacitance of such electrodes, experiments using square wave excitation of the system in the kHz frequency range show a promising reaction of the cell to this treatment. More in-depth analysis of the used electrode material reveals the need to insulate future EFM electrodes in order to prevent oxidative dissolution. However, this work shows that the principle of using EFM electrodes to manipulate transient oscillations is physically sound.

PCB Rogowski Coil sensor by using Saw blade pattern for arcing fault detection

Rogowski is a special current transformer and has been categorised as a low-power stand-alone current sensor. This sensor is designed by using a Saw blade pattern with 50 turns and 100 turns. This number of turns will impact the increment of the sensitivity of the sensor. Rogowski coil is used for measuring the alternating current (AC) and high-speed current pulses. The PCB Rogowski Coil will detect the arcing fault that design with AutoCAD software after that import to CST software. An arc is created when the electrical current jumps the gap between two conductive materials. The most common causes of arcs include worn contacts in electrical equipment, damage to insulation, break in a cable and loose connections. In order to reduce the arc fault risk, the arc fault interrupter (AFI) technology and arc fault detectors (AFD) have been developed. However, these devices are most suitable for domestic application or low voltage (LV). This paper proposed a simulation using AutoCAD and CST software to design a Rogowski coil and the Rogowski Coil sensor will be tested by using CST software in terms of radiation pattern. The biggest radiation pattern in red colour is the saw blade pattern in 100 turns at 2 KHz frequency, the radiation pattern covering entire sensor area compared with other radiation patterns with other frequency. The main lobe magnitude for 2 KHz frequency is 46.8 dB, main lobe direction is 180 deg, angular width is 153.4 deg and the side lobe level is zero. This is the best number of turn and frequency compared to 50 turn saw blade sensor.

Preparation and analysis of dielectric behaviour of BCZT based flexible PVDF polymer composite membrane

In this paper, Barium Calcium Zirconium Titanate (Ba0.86 Ca0.14 Zr0.05 Ti0.95 O3) ceramic powder samples were prepared by the solid-state reaction process. After that, it is mixed with polyvinylidene fluoride (PVDF) to form composite membrane, which is fabricated using the solution cast method. Two membranes were prepared with 15 wt% and 50 wt% filler concentrations of BCZT with PVDF matrix. Dielectric behaviours of prepared composite membrane are analyzed, and these various analyses of composite film are also compared with each other. In this, we see that the increasing addition of lead-free based inorganic filler with an organic PVDF matrix enhanced the dielectric constant five times for the frequency 1KHz and reduction in the losses and increases the conductivity of the composite as the filler weight percentage increased. These fabricated composite membrane can be used for wearable biomedical devices, soft robotics and flexible energy storage capacitors.

Speech audiometry indicators for diagnosis of hidden hearing loss in MP3 player users

StudywasconductedonthebasisoftheNationalCenterofAudiologyandS.tudy was conducted on the basis of the National Center of Audiology and S. KhechinashviliUniversityClinic.Apopulationof18to30yearsofagewasin-Khechinashvili University Clinic. A population of 18 to 30 years of age was in-cludedinthestudy–40subjectsand15individualsintheagegroup(50to55cluded in the study – 40 subjects and 15 individuals in the age group (50 to 55 years)wereselectedbasedontheirwillingnesstoparticipateinthestudybasedyears) were selected based on their willingness to participate in the study based onnon-randomcomplaintcomplaintsattheclinic.Themaingroupincluded22on non-random complaint complaints at the clinic. The main group included 22 (40%)MP3users,whilethecontrolgroupincluded18(33%)non–usersand(40%) MP3 users, while the control group included 18 (33%) non – users and 15(27%)personsinthemiddleagegroup.Ofthese,37(67%)werefemaleand15 (27%) persons in the middle age group. Of these, 37 (67%) were female and 18(33%)weremale.Auditorythresholdsweremeasuredmonaurallybythepure18 (33%) were male. Auditory thresholds were measured monaurally by the pure toneaudiometerwithinthebandof0.125-16kHzfrequencies.Attheprincipaltone audiometer within the band of 0.125-16 kHz frequencies. At the principal speechfrequencylink,1-8kHz,thethresholdsinplayermusicusersdidnotspeech frequency link, 1-8 kHz, the thresholds in player music users did not differfromthoseinnon-users.Athigherfrequenciesfrom9-16kHz,however,differ from those in non-users. At higher frequencies from 9-16 kHz, however, theplayermusicfanspossessedgreaterthresholdsmorethan25dB.Inanoisythe player music fans possessed greater thresholds more than 25 dB. In a noisy environment,speechaudiometryinnoisewasperformedtotesttheabilitytoenvironment, speech audiometry in noise was performed to test the ability to correctlydistinguishwords.Byexaminingtheresultsofspeechaudiometry,itcorrectly distinguish words. By examining the results of speech audiometry, it wasfoundthatoutof100wordsandthentheyrepeatthem.Mp3playeruserswas found that out of 100 words and then they repeat them. Mp3 player users hadworseresultthanadultgroup,higherunderstandingresultshadnon-users.had worse result than adult group, higher understanding results had non-users. The process of hearing disturbances along with a group-systematic character seemedthustoownanindividual-sensitivequalityalso.Systematicaudiometricalseemed thus to own an individual-sensitive quality also. Systematic audiometrical inspectionofpersonalmusicplayerfollowersisrecommendedforanin-timeinspection of personal music player followers is recommended for an in-time disclosureofahearingdisorderandanimmediatestartthenofcorrespondingdisclosure of a hearing disorder and an immediate start then of corresponding treatmentandpreventivemeans.Thehearingtestinghastoincludehightonetreatment and preventive means. The hearing testing has to include high tone frequencies,9-16kHz.Speechaudiometryinthenoisecanbeconsideredlikefrequencies, 9-16 kHz. Speech audiometry in the noise can be considered like goldstandardfordiagnosticofHiddenHearingLoss.gold standard for diagnostic of Hidden Hearing Loss.