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Background: Noise has been reported to occur with relatively high frequency after conventional total knee arthroplasty (C-TKA), and this may impact the incidence of patient satisfaction and function. The purpose of this study was to compare the rate of patient-reported prosthetic noise generation after robotically-assisted TKA (RA-TKA) and C-TKA. Methods: A retrospective study was conducted of unilateral primary RA-TKAs and C-TKAs performed between 2018 and 2021. Patients completed a survey consisting of 4 Likert scale questions related to prosthetic noise generation and Knee Injury and Osteoarthritis Score Joint Replacement and Forgotten Joint Score were assessed prospectively preoperatively and at a minimum of 1-year of clinical follow-up. Statistical analysis was done utilizing T-tests and chi-square tests, with statistical significance defined as a P-value < .05. Results: One hundred sixty-two RA-TKAs and 320 C-TKAs with similar baseline characteristics and functions were included. There were no significant differences in hearing or feeling grinding, popping, clicking, or clunking (40.7% vs 38.1%; P = .647) between groups. Most RA-TKAs and C-TKAs were not dissatisfied regarding noise generation (70.4% vs 73.1%; P = .596). In both cohorts, patients who reported noise generation had lower average Forgotten Joint Scores (45.5 vs 66.1; P < .001) and lower postoperative Knee Injury and Osteoarthritis Score Joint Replacement scores (72.0 vs 81.4; P < .001) than those who did not experience noise generation. Conclusions: While RA-TKA may facilitate soft tissue balancing, there were no differences in prosthetic noise generation between RA-TKA and C-TKA. However, those who experience implant-generated noise have lower functional outcome scores.

The problem of noise reduction in supersonic aircraft design is one of the key problems, the solution of which largely determines the speed of development of supersonic aviation as a whole. The present study examines the noise generation during flights of supersonic civil aircraft. The effect of a thermally stratified energy source (TSS) used to control the supersonic flow past a pointed cylinder aerodynamic model on the near-field and ground pressure signatures, as well as on the perceived loudness in decibels (PLdB) on the ground, is evaluated. The complex conservative difference schemes, Tomas' waveform parameter method, and Stevens' algorithm Mark VII are used for near-field modeling, obtaining the ground pressure signature, and the evaluation of the PLdB on the ground, accordingly. The fields of flow parameters and the dynamics of a drag force are researched at the variation of temperatures in layers of TSS and for different numbers of layers. Simulations showed that changing the surface pressure due to drag reduction does not necessarily imply a change in the PLdB on the ground. In particular, it has been shown that when performing the flow control at freestream Mach numbers 1.5–2 using TSSs with the number of layers from 2.5 to 7.5 and rarefaction parameters in the layers from 0.15 to 0.3, some weakening of the bow shock wave in the near-field pressure signature due to the effect of TSS occurs, and no additional noise impact on the ground is introduced. [ABSTRACT FROM AUTHOR]

Numerous old images and videos were captured and stored under unfavorable conditions. Hence, old images and videos have uncertain and different noise patterns compared with those of modern ones. Denoising old images is an effective technique for reconstructing a clean image containing crucial information. However, obtaining noisy-clean image pairs for denoising old images is difficult and challenging for supervised learning. Preparing such a pair is expensive and burdensome, as existing denoising approaches require a considerable number of noisy-clean image pairs. To address this issue, we propose a robust noise-generation generative adversarial network (NG-GAN) that utilizes unpaired datasets to replicate the noise distribution of degraded old images inspired by the CycleGAN model. In our proposed method, the perception-based image quality evaluator metric is used to control noise generation effectively. An unpaired dataset is generated by selecting clean images with features that match the old images to train the proposed model. Experimental results demonstrate that the dataset generated by our proposed NG-GAN can better train state-of-the-art denoising models by effectively denoising old videos. The denoising models exhibit significantly improved peak signal-to-noise ratios and structural similarity index measures of 0.37 dB and 0.06 on average, respectively, on the dataset generated by our proposed NG-GAN. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the acoustic analogy method in relation to the sound radiation of a turbulent subsonic jet. This method of describing aerodynamic sound generation by turbulent flows is based on the use of a linear propagation operator with a random source on the right side. The main problem here is the choice of an effective way to separate the left side of the equation, which is responsible for the propagation of sound waves, and the right part, which is responsible for sound generation, so that the noise calculation result corresponds to experimental data and physical ideas about noise generation by turbulence. One of the unsolved problems of the approach, which is common in most acoustic analogies, is the problem of the so-called "shear noise" associated with the excitation of shear flow disturbances by sources and the additional contribution of these disturbances to sound radiation. It is still unclear whether the shear component of the noise is a reflection of real physical processes or is associated with the transformation of equations and inaccurate modeling of sources. Here, within the framework of the problem formulated above, we consider an acoustic analogy, in which the linearized Euler equations are used as the propagation operator. In this description, the propagation operator contains vortex modes, which leads to the appearance of a shear noise component that arises due to the pumping of vortex disturbances by the sources. When modeling sound sources, hypotheses about the quadrupole nature isotropy of sound sources, as well as the spatial uncorrelation of sound source production, are used. To validate the model, the measurement data of the sound emission of the jet using the azimuthal decomposition method are used. The comparison of the model and experiment indicates the absence of a shear component in the jet noise. This makes it possible to conclude that the idea of pumping linear vortex perturbations of the mean flow by nonlinear turbulent pulsations that is used in the considered acoustic analogy does not correspond to the real mechanism of noise generation by a turbulent jet. Possible causes of the discrepancy between the model and the data of acoustic measurements are analyzed. Possible ways of solving this problem, which make it possible to effectively separate the left side of the equation that is responsible for the propagation of sound waves and the right nonlinear part that is responsible for sound generation are considered. [ABSTRACT FROM AUTHOR]

In this paper, we study the mechanism of noise generation in a turbulent jet using the acoustic analogy method. The aim of this study is to develop a sound source model that does not contain the so-called shear noise component. This condition was formulated earlier as a result of the analysis of multi-microphone acoustic measurements of the jet, which showed that the acoustic analogies that take into account shear noise disagree with the experimental data. The model proposed here is based on the separation of acoustic and hydrodynamic variables and the use of a propagation operator that does not contain hydrodynamic degrees of freedom. This approach makes it possible to eliminate naturally the shear component in the sound emission and achieve good agreement with the acoustic measurement data. A sound source is simulated under the assumptions of quadrupole and isotropy of the pulsations responsible for sound radiation. The simulation results are compared with experimental data on the directivity of the main azimuthal harmonics of the sound radiation of the jet at a velocity of 120 m/s. The obtained results provide an important contribution to understanding the nature of sound-emitting turbulence in shear flows. [ABSTRACT FROM AUTHOR]

The problem of noise reduction in supersonic aircraft design is one of the key problems, the solution of which largely determines the speed of development of supersonic aviation as a whole. The present study examines the noise generation during flights of supersonic civil aircraft. The effect of a thermally stratified energy source (TSS) used to control the supersonic flow past a pointed cylinder aerodynamic model on the near-field and ground pressure signatures, as well as on the perceived loudness in decibels (PLdB) on the ground, is evaluated. The complex conservative difference schemes, Tomas’ waveform parameter method, and Stevens’ algorithm Mark VII are used for near-field modeling, obtaining the ground pressure signature, and the evaluation of the PLdB on the ground, accordingly. The fields of flow parameters and the dynamics of a drag force are researched at the variation of temperatures in layers of TSS and for different numbers of layers. Simulations showed that changing the surface pressure due to drag reduction does not necessarily imply a change in the PLdB on the ground. In particular, it has been shown that when performing the flow control at freestream Mach numbers 1.5–2 using TSSs with the number of layers from 2.5 to 7.5 and rarefaction parameters in the layers from 0.15 to 0.3, some weakening of the bow shock wave in the near-field pressure signature due to the effect of TSS occurs, and no additional noise impact on the ground is introduced.

The paper describes first observation of parametric generation of noise in a composite multiferroic resonator. Resonator of a disk shape contains two mechanically coupled layers, one of which is the amorphous ferromagnet (FM) FeBSiC and the other is the piezoelectric (PE) lead zirconate titanate. DC magnetic field of 0â€"100 Oe is applied parallel to the plane of the resonator. Resonator is excited in the frequency range f = 2â€"10 kHz by a harmonic electric field with amplitude of up to 330 V cmâˆ'1 applied to the PE layer. Changes in the magnetization of the resonator caused by the converse magnetoelectric effect were recorded using an electromagnetic coil. With an increase in the excitation field to the threshold value, the parametric generation of harmonics and subharmonics with a discrete spectrum is observed, which then turns into a stochastic mode and a continuous spectrum of frequencies is generated. Noise density is hysterically dependent on the excitation field and non-monotonically depends on the dc magnetic field. Theory of parametric generation of the noise in a multiferroic resonator is developed, taking into account excitation of acoustic resonances and magnetoacoustic nonlinearity of the FM layer of the resonator. Theory, qualitatively describes the main characteristics of noise generation. [ABSTRACT FROM AUTHOR]

The paper reports the result of our research on graded-gap diodes with a cathode static domain as possible noise sources for different modern applications based on the use of THz wave frequencies. Such diodes represent a two-terminal n+ – n – n – n+ structure containing a cathode graded-gap layer with a band gap that increases from the cathode contact towards the n-region. We study GaN and AlN based diodes with InzGa1-zN and InzAl1-zN based graded-gap layers, respectively. It is shown that the localization of a strong electric field and low values of impact ionization threshold can be achieved by using a graded-gap layer with a narrow-gap material on the cathode. The diode simulation is performed using ensemble Monte Carlo technique. Noise generation is investigated numerically with time sampling of electric current over the time domain. The influence of scattering mechanisms acting on charge carriers on the noise properties of the diode is explored. Analyzing the noise power spectral density (NPSD), it is found that maximum NPSD can be observed in GaN diodes with InzGa1-zN layer, and the NPSD magnitude depends both on the size of the n–-region (at a fixed diode length) and on the position of the graded-gap layer with respect to the end of the high resistance region (n–). It is established that polar phonon scattering and alloy-disorder scattering are the main mechanisms affecting the noise properties of the diodes. It is shown that the diodes demonstrate bias voltage regions where the dependence of NPSD on bias voltage is linear, and the value of NPSD increases by an order of magnitude. [ABSTRACT FROM AUTHOR]

Numerous old images and videos were captured and stored under unfavorable conditions. Hence, old images and videos have uncertain and different noise patterns compared with those of modern ones. Denoising old images is an effective technique for reconstructing a clean image containing crucial information. However, obtaining noisy-clean image pairs for denoising old images is difficult and challenging for supervised learning. Preparing such a pair is expensive and burdensome, as existing denoising approaches require a considerable number of noisy-clean image pairs. To address this issue, we propose a robust noise-generation generative adversarial network (NG-GAN) that utilizes unpaired datasets to replicate the noise distribution of degraded old images inspired by the CycleGAN model. In our proposed method, the perception-based image quality evaluator metric is used to control noise generation effectively. An unpaired dataset is generated by selecting clean images with features that match the old images to train the proposed model. Experimental results demonstrate that the dataset generated by our proposed NG-GAN can better train state-of-the-art denoising models by effectively denoising old videos. The denoising models exhibit significantly improved peak signal-to-noise ratios and structural similarity index measures of 0.37 dB and 0.06 on average, respectively, on the dataset generated by our proposed NG-GAN.

In the present paper, noise generation due to supersonic hot jet impingement (M=1.4 and Tt=950 K) to an inclined flat plate is experimentally investigated. In general, four types of acoustic waves are defined for jet impingement: acoustic waves generated by the shear layer of the main jet (type-A), by the impingement region (type-B), by the shear layer of the wall/jet downstream of the impinging region (type-C), and tonal acoustic waves observed in normal impingement. An attempt is made to understand the sources of the noise of the impinging jet by comparing acoustic scalograms of the impinging and free jets at the far-field. It is determined that the type-C acoustic wave images are similar to the far-field scalogram images of the free jet at the same polar angles. Further, the type-B acoustic waves in oblique jet impingement have similar acoustic signature with tonal noise due to normal jet impingement.

The influence of the geometric and regime parameters of a resonance infrared jet-edge generator on the formation, in its resonance tube, of a sound field with a predominant discrete tone at the fundamental frequency of the generator resonant cavity was investigated. A parametric investigation of the self-sustained oscillation processes arising in the resonance tube of the generator as a result of the interaction of a subsonic gas jet and a supersonic one with its resonant cavity has been performed. The nonstationary structure of the gas flow inside this cavity, characteristic of the self-sustained oscillation interaction of a gas jet with an obstacle, is discussed. Prominence is given to the study of the pattern of the gas flow inside the resonant cavity and the amplitude-frequency characteristics of the wave process in it. Recommendations for designing a resonance infrasound jet-edge generator with regard for its use in actual practice are given. [ABSTRACT FROM AUTHOR]

The rod-airfoil configuration is a fundamental study to understand sound generation processes and the acoustic phenomena in the application of turbines, fans, and airfoils. In the present research, the noise that is originated by the rod-airfoil configuration is examined using numerical methods which are Large Eddy Simulation (LES), and Reynolds Averaged Navier Stokes (RANS) models, coupled with an FFOWCS-WILLIAMSHAWKINGS (FW-H) technique. For the RANS method, k-ω SST and Spalart Allmaras (S-A) turbulence models are utilized in order to investigate the capability of different models for the analysis of the aeroacoustic flow field. The ANSYS FLUENT solver is chosen to carry out the numerical simulations. The examined rod and chord diameter Reynolds numbers are 48000 and 480000, respectively and the Mach number is 0.2. Results are obtained for both in the near field and acoustic far-field. The obtained numerical results are verified with an experimental study from the literature, and the results of both approaches are compared with each other and the experiment. Comparisons are performed for mean velocity profiles in the rod and airfoil wakes, pressure spectra and power spectral density. The results obtained show that LES is preferable for this problem as it is capable of capturing the flow separation, reattachments, vortex street, and various length scales of turbulence. Although both RANS and LES methods provide a consistent flow field with experimental methods, the RANS approach overestimates the vortex shedding frequency and Strouhal number. The RANS model predicts the flow field well; however, it overestimates the noise spectra. The LES model predicts satisfactory acoustic spectra. [ABSTRACT FROM AUTHOR]

The ability of some species of owl to fly in effective silence is unique among birds and provides a distinct hunting advantage, but it remains a mystery as to exactly what aspects of the owl and its flight are responsible for this dramatic noise reduction. Crucially, this mystery extends to how the flow physics may be leveraged to generate noise-reduction strategies for wider technological application. We review current knowledge of aerodynamic noise from owls, ranging from live owl noise measurements to mathematical modeling and experiments focused on how owls may disrupt the standard routes of noise generation. Specialized adaptations and foraging strategies are not uniform across all owl species: Some species may not have need for silent flight, or their evolutionary adaptations may not be effective for useful noise reduction for certain species. This hypothesis is examined using mathematical models and borne out where possible by noise measurements and morphological observations of owl feathers and wings. [ABSTRACT FROM AUTHOR]

In the present paper, noise generation due to supersonic hot jet impingement (M=1.4 and Tt=950 K) to an inclined flat plate is experimentally investigated. In general, four types of acoustic waves are defined for jet impingement: acoustic waves generated by the shear layer of the main jet (type-A), by the impingement region (type-B), by the shear layer of the wall/jet downstream of the impinging region (type-C), and tonal acoustic waves observed in normal impingement. An attempt is made to understand the sources of the noise of the impinging jet by comparing acoustic scalograms of the impinging and free jets at the far-field. It is determined that the type-C acoustic wave images are similar to the far-field scalogram images of the free jet at the same polar angles. Further, the type-B acoustic waves in oblique jet impingement have similar acoustic signature with tonal noise due to normal jet impingement. [ABSTRACT FROM AUTHOR]

The influence of the geometric and regime parameters of a resonance infrared jet-edge generator on the formation, in its resonance tube, of a sound field with a predominant discrete tone at the fundamental frequency of the generator resonant cavity was investigated. A parametric investigation of the self-sustained oscillation processes arising in the resonance tube of the generator as a result of the interaction of a subsonic gas jet and a supersonic one with its resonant cavity has been performed. The nonstationary structure of the gas flow inside this cavity, characteristic of the self-sustained oscillation interaction of a gas jet with an obstacle, is discussed. Prominence is given to the study of the pattern of the gas flow inside the resonant cavity and the amplitude-frequency characteristics of the wave process in it. Recommendations for designing a resonance infrasound jet-edge generator with regard for its use in actual practice are given. [ABSTRACT FROM AUTHOR]

Abstract: The paper studies the generation of acoustic waves near the boundaries of swirling and nonswirling turbulent jets outside a jet flow. Nonstationary motion of the medium is analyzed. In the case of swirling jets, the occurrence and propagation of perturbations were studied experimentally, while in the case of free turbulent jets, both experimentally and numerically on the basis of LES technology. The results of the study show that, near the jet boundaries, there is a region in which the phase difference between pressure and velocity pulsations at fixed frequencies is 90° or more; i.е., there are no perturbations propagating outward. The phases of velocity and pressure pulsations coincide starting from some significant distance from the jet boundaries. The region in which the phase difference varies from 90° to 0° lies outside the jet flow and is presumably the sound generation region. It is proposed that this region be identified with the near acoustic field of jets. [ABSTRACT FROM AUTHOR]

Background: Noise has been reported to occur with relatively high frequency after conventional total knee arthroplasty (C-TKA), and this may impact the incidence of patient satisfaction and function. The purpose of this study was to compare the rate of patient-reported prosthetic noise generation after robotically-assisted TKA (RA-TKA) and C-TKA., Methods: A retrospective study was conducted of unilateral primary RA-TKAs and C-TKAs performed between 2018 and 2021. Patients completed a survey consisting of 4 Likert scale questions related to prosthetic noise generation and Knee Injury and Osteoarthritis Score Joint Replacement and Forgotten Joint Score were assessed prospectively preoperatively and at a minimum of 1-year of clinical follow-up. Statistical analysis was done utilizing T-tests and chi-square tests, with statistical significance defined as a P -value < .05., Results: One hundred sixty-two RA-TKAs and 320 C-TKAs with similar baseline characteristics and functions were included. There were no significant differences in hearing or feeling grinding, popping, clicking, or clunking (40.7% vs 38.1%; P  = .647) between groups. Most RA-TKAs and C-TKAs were not dissatisfied regarding noise generation (70.4% vs 73.1%; P  = .596). In both cohorts, patients who reported noise generation had lower average Forgotten Joint Scores (45.5 vs 66.1; P < .001) and lower postoperative Knee Injury and Osteoarthritis Score Joint Replacement scores (72.0 vs 81.4; P < .001) than those who did not experience noise generation., Conclusions: While RA-TKA may facilitate soft tissue balancing, there were no differences in prosthetic noise generation between RA-TKA and C-TKA. However, those who experience implant-generated noise have lower functional outcome scores., (© 2023 The Authors.)

The high variable flux density in the air‐gap of fault‐tolerant flux‐switching permanent‐magnet (FT‐FSPM) machine results in rich harmonics of the magnetic field, thus generating large vibration and noise. This study proposes two novel FT‐FSPM machines which can effectively reduce the radial pressure, thus reducing the vibration and noise. First, the radial pressure of the initial FT‐FSPM machine is analysed. Second, the novel proposed FT‐FSPM machines are introduced and analysed. Third, the electromagnetic performance, including back electromotive force, output torque, inductance, and radial pressure harmonics, of the initial and the two proposed machines are compared by finite element method. Then, the vibration modes with corresponding natural frequencies are predicted. The vibration and noise are simulated by boundary element method. Finally, the effectiveness of the low‐noise design is verified by measurement results. [ABSTRACT FROM AUTHOR]

In this modern era of thriving technology, the data being gathered through way of private in addition to public businesses is increasing each day. But in recent times people are more worried about their data and privateness being preserved at the same time as use of their data in other analysis purpose. Thus Privacy-Preserving Data Mining (PPDM) method has been proposed to permit the extraction of understanding from data at the same time as keeping the privateness of people. The primary purpose of our project is on preserving privacy for healthcare records as privateness lacks in Medical data. Privacy-Preserving Data Mining (PPDM) offers with shielding the privacy of individual's data or sensitive data without the utility of data. Therefore the strategies like anonymization, randomization are used to attain the intention. However, unfortunately anonymization results in certain level of information loss while preserving privacy. In order to overcome this problem, perturbation technique is carried out. Our challenge initiates with cleaning and preprocessing followed by ensemble classification and proceeded with perturbation to attain the goal. This method focuses on preserving privacy by perturbing the sensitive attributes in the Medical data without causing loss to the information in the process. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of head on quenching (HOQ) (an extreme case of flame/wall interactions) as a source of sound generation, which in turn can trigger combustion instabilities and enhanced noise levels. High-fidelity numerical simulations are performed to investigate the impact of wall temperature, high chamber pressures and Lewis number of the fuel on the noise generation. It is demonstrated by theory and simulations that the underlying mechanism of sound generation is flame surface destruction (flame annihilation). Special emphasis is put on chemical modeling where simple and complex mechanisms were compared: it is shown that simple chemistry simulations overestimate the generated pressure peaks due to a too fast extinction of the heat release rate compared to the complex scheme. In contrast to the simple mechanism, the complex scheme accounts for minor and intermediate species production and destruction which slows down the extinction process and thus lead to a lower sound level. This effect has to be taken into account, especially in the context of Large Eddy Simulation (LES) of combustion instabilities and combustion noise where simple chemical descriptions are often employed. [ABSTRACT FROM AUTHOR]

Background: There are several causes of patient dissatisfaction after total knee arthroplasty (TKA). This study hypothesized that noise occurring in the knee would worsen patient satisfaction after TKA.Methods: We mailed a newly developed questionnaire to 103 consecutive participants who were followed for one year, resulting in data from 61 knees in 60 patients (47 women and 13 men, mean age 73 years) who underwent cruciate-substituting TKA. We evaluated postoperative range of motion, knee instability, and the 2011 Knee Society Score in terms of noise generation after TKA.Results: Over half of the patients noticed postoperative noise that occurred during the mid range of knee motion, but noise was not associated with feelings of instability. Postoperative range of motion differed significantly between the group with noise (122.8 ± 12.0°) and that without noise (106.3 ± 23.3°). The patellar tilt angle was also significantly larger in the group with noise (7.4 ± 5.5°) than that without noise (3.3 ± 2.6°). However, collateral ligament laxity had no significant effect on noise, and the 2011 Knee Society Score did not differ significantly different between the noise and no-noise groups.Conclusion: Our hypothesis was refuted, and these findings suggest patient satisfaction after TKA is influenced more by good knee function than by noise generation. [ABSTRACT FROM AUTHOR]