High Dimensional Parameter Fitting of the Keller–Miksis Equation on an Experimentally Observed Dual-Frequency Driven Acoustic Bubble

A parameter identification technique of an underlying bubble model of an experimentally observed single bubble in a cluster under dual-frequency external forcing is presented. The measurements are carried out via high-speed camera recordings at a rate of 162750 frames per second. The used frequencies during the experiment are 25 kHz and 50 kHz. With a digital image processing technique, the measured bubble radius as a function of time is determined. The employed governing equation for the parameter fitting is the Keller–Miksis equation being a second order ordinary differential equation. The unknown four-dimensional parameter space is composed by the two pressure amplitudes, the phase shift of the dual-frequency driving and the equilibrium size of the bubble. In order to obtain an optimal parameter set within reasonable time, an in-house initial value problem solver is used running on a graphics processing unit (GPU). The error function measuring the distance between the numerical simulations and the measurement is based on the identification of the maximum bubble radii during each subsequent period of the external forcing. The results show a consistent estimation of both pressure amplitudes. The optima of phase shift and equilibrium bubble size are less significant due to a valley-like shape of the error function. Nevertheless, reasonable values are found that lead to estimations of pressure and temperature peaks during bubble collapse.

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Analytical Models for the Computation of Error Probability of Multi-Level Phase Shift Keying Modulation Scheme

British Journal of Computer, Networking and Information Technology ◽

10.52589/bjcnit-lsfcmvli ◽

2021 ◽

Vol 4 (1) ◽

pp. 13-20

Author(s):

Isaac A. E. ◽

Dike H.U.

Keyword(s):

Phase Shift ◽

Error Probability ◽

Error Function ◽

Density Ratio ◽

Analytical Models ◽

Modulation Scheme ◽

Noise Power ◽

Phase Shift Keying ◽

Shift Keying ◽

Multi Level

In this paper, analytical models for the computation of error probability (BER) of the Multi-level Phase Shift Keying (MPSK) modulation scheme is presented. Analytical models for computing MPSK bit error probability based on Q function, error function (erf) and complementary error function (erfc) are presented. Also, an analytical model for computing the symbol error rate for MPSK is presented. Furthermore, a generalized analytical expression for BER as a function of modulation order (M) and energy per bit to noise power density ratio (Eb/No) is presented. The BER was computed for various values of M (2 ≤ M ≤ 256) and Eb/No (0 dB ≤ Eb/No ≤ 14 Db). The results showed that at Eb/No =12 dB, a BER of 9.006E-09 is realized for M =2 and M =4 whereas BER of 1.056E-01 is realized for M = 256. Also, for the same M = 2 , the value of BER decreased from 1.2501E-02 at Eb/No = 4 dB to 9.0060E-09at Eb/No =12 dB. Generally, the results showed that for the MPSK modulation scheme, for a given value of Eb/No, the lower modulation order (M) has a lower BER and for a given modulation order, (M) the BER decreases as Eb/No increases.

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On the boundary integral method for the rebounding bubble

Journal of Fluid Mechanics ◽

10.1017/s0022112006003296 ◽

2007 ◽

Vol 570 ◽

pp. 407-429 ◽

Cited By ~ 58

Author(s):

M. LEE ◽

E. KLASEBOER ◽

B. C. KHOO

Keyword(s):

Energy Loss ◽

Integral Method ◽

Bubble Radius ◽

Experimental Studies ◽

Boundary Integral ◽

Boundary Integral Method ◽

Bubble Collapse ◽

Solid Boundary ◽

Bubble System ◽

Toroidal Bubble

The formation of a toroidal bubble towards the end of the bubble collapse stage in the neighbourhood of a solid boundary has been successfully studied using the boundary integral method. The further evolution (rebound) of the toroidal bubble is considered with the loss of system energy taken into account. The energy loss is incorporated into a mathematical model by a discontinuous jump in the potential energy at the minimum volume during the short collapse–rebound period accompanying wave emission. This implementation is first tested with the spherically oscillating bubble system using the theoretical Rayleigh–Plesset equation. Excellent agreement with experimental data for the bubble radius evolution up to three oscillation periods is obtained. Secondly, the incorporation of energy loss is tested with the motion of an oscillating bubble system in the neighbourhood of a rigid boundary, in an axisymmetric geometry, using a boundary integral method. Example calculations are presented to demonstrate the possibility of capturing the peculiar entity of a counterjet, which has been reported only in recent experimental studies.

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Phase Noise Influence in a Dual-Frequency Laser Phase-Shift Range Finder

IEEE Photonics Journal ◽

10.1109/jphot.2017.2787687 ◽

2018 ◽

Vol 10 (1) ◽

pp. 1-10

Author(s):

Hongzhi Yang ◽

Changming Zhao ◽

Haiyang Zhang ◽

Suhui Yang ◽

Xinyuan Zheng

Keyword(s):

Phase Shift ◽

Phase Noise ◽

Range Finder ◽

Dual Frequency ◽

Frequency Laser

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GPU Accelerated real-time Melanoma Detection

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.13169 ◽

2018 ◽

Vol 7 (3) ◽

pp. 1208

Author(s):

Ajai Sunny Joseph ◽

Elizabeth Isaac

Keyword(s):

Real Time ◽

Video Processing ◽

Processing Technique ◽

Video Data ◽

Image Processing Technique ◽

Processing Unit ◽

Central Processing ◽

Melanoma Detection ◽

Real Time Analysis ◽

Graphical Processing

Melanoma is recognized as one of the most dangerous type of skin cancer. A novel method to detect melanoma in real time with the help of Graphical Processing Unit (GPU) is proposed. Existing systems can process medical images and perform a diagnosis based on Image Processing technique and Artiﬁcial Intelligence. They are also able to perform video processing with the help of large hardware resources at the backend. This incurs signiﬁcantly higher costs and space and are complex by both software and hardware. Graphical Processing Units have high processing capabilities compared to a Central Processing Unit of a system. Various approaches were used for implementing real time detection of Melanoma. The results and analysis based on various approaches and the best approach based on our study is discussed in this work. A performance analysis for the approaches on the basis of CPU and GPU environment is also discussed. The proposed system will perform real-time analysis of live medical video data and performs diagnosis. The system when implemented yielded an accuracy of 90.133% which is comparable to existing systems.

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GPU accelerated study of a dual-frequency driven single bubble in a 6-dimensional parameter space: The active cavitation threshold

Ultrasonics Sonochemistry ◽

10.1016/j.ultsonch.2020.105067 ◽

2020 ◽

Vol 67 ◽

pp. 105067 ◽

Cited By ~ 5

Author(s):

Ferenc Hegedűs ◽

Kálmán Klapcsik ◽

Werner Lauterborn ◽

Ulrich Parlitz ◽

Robert Mettin

Keyword(s):

Parameter Space ◽

Single Bubble ◽

Dual Frequency ◽

Dimensional Parameter ◽

Cavitation Threshold

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From model to radar variables: a new forward polarimetric radar operator for COSMO

Atmospheric Measurement Techniques ◽

10.5194/amt-11-3883-2018 ◽

2018 ◽

Vol 11 (7) ◽

pp. 3883-3916 ◽

Cited By ~ 6

Author(s):

Daniel Wolfensberger ◽

Alexis Berne

Keyword(s):

Phase Shift ◽

Solid Phase ◽

Weather Prediction ◽

Doppler Spectrum ◽

Polarimetric Radar ◽

Dual Frequency ◽

Differential Phase Shift ◽

Radar Observations ◽

Differential Phase ◽

Differential Reflectivity

Abstract. In this work, a new forward polarimetric radar operator for the COSMO numerical weather prediction (NWP) model is proposed. This operator is able to simulate measurements of radar reflectivity at horizontal polarization, differential reflectivity as well as specific differential phase shift and Doppler variables for ground based or spaceborne radar scans from atmospheric conditions simulated by COSMO. The operator includes a new Doppler scheme, which allows estimation of the full Doppler spectrum, as well a melting scheme which allows representing the very specific polarimetric signature of melting hydrometeors. In addition, the operator is adapted to both the operational one-moment microphysical scheme of COSMO and its more advanced two-moment scheme. The parameters of the relationships between the microphysical and scattering properties of the various hydrometeors are derived either from the literature or, in the case of graupel and aggregates, from observations collected in Switzerland. The operator is evaluated by comparing the simulated fields of radar observables with observations from the Swiss operational radar network, from a high resolution X-band research radar and from the dual-frequency precipitation radar of the Global Precipitation Measurement satellite (GPM-DPR). This evaluation shows that the operator is able to simulate an accurate Doppler spectrum and accurate radial velocities as well as realistic distributions of polarimetric variables in the liquid phase. In the solid phase, the simulated reflectivities agree relatively well with radar observations, but the simulated differential reflectivity and specific differential phase shift upon propagation tend to be underestimated. This radar operator makes it possible to compare directly radar observations from various sources with COSMO simulations and as such is a valuable tool to evaluate and test the microphysical parameterizations of the model.

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Cavitation Bubble Collapse Near a Heated Wall and Its Effect on the Heat Transfer

Journal of Heat Transfer ◽

10.1115/1.4024071 ◽

2013 ◽

Vol 136 (2) ◽

Cited By ~ 10

Author(s):

Bin Liu ◽

Jun Cai ◽

Xiulan Huai ◽

Fengchao Li

Keyword(s):

Heat Transfer ◽

Cavitation Bubble ◽

Stokes Equations ◽

Saturated Vapor ◽

Bubble Diameter ◽

Bubble Radius ◽

Heated Wall ◽

Bubble Collapse ◽

Flow State ◽

Vof Model

In the present work, a numerical investigation on the mechanism of heat transfer enhancement by a cavitation bubble collapsing near a heated wall has been presented. The Navier–Stokes equations and volume of fluid (VOF) model are employed to predict the flow state and capture the liquid-gas interface. The model was validated by comparing with the experimental data. The results show that the microjet violently impinges on the heated wall after the bubble collapses completely. In the meantime, the thickness of the thermal boundary layer and the wall temperature decrease significantly within the active scope of the microjet. The fresh low-temperature liquid and the impingement brought by the microjet should be responsible for the heat transfer reinforcement between the heated wall and the liquid. In addition, it is found that the impingement width of the microjet on the heated wall always keeps 20% of the bubble diameter. And, the enhancement degree of heat transfer significantly depends on such factors as stand-off distance, saturated vapor pressure, and initial bubble radius.

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Investigation of Error Distribution in the Back-Calculation of Breakage Function Model Parameters via Nonlinear Programming

Minerals ◽

10.3390/min11040425 ◽

2021 ◽

Vol 11 (4) ◽

pp. 425

Author(s):

Jihoe Kwon ◽

Heechan Cho

Keyword(s):

Flat Surface ◽

Error Function ◽

Model Parameters ◽

Dimensional Parameter ◽

Parameter Spaces ◽

Initial Values ◽

Wide Range ◽

Minimum Number ◽

Breakage Function ◽

Back Calculation

Despite its effectiveness in determining breakage function parameters (BFPs) for quantifying breakage characteristics in mineral grinding processes, the back-calculation method has limitations owing to the uncertainty regarding the distribution of the error function. In this work, using Korean uranium and molybdenum ores, we show that the limitation can be overcome by searching over a wide range of initial values based on the conjugate gradient method. We also visualized the distribution of the sum of squares of the error in the two-dimensional parameter space. The results showed that the error function was strictly convex, and the main problem in the back-calculation of the breakage functions was the flat surface of the objective function rather than the occurrence of local minima. Based on our results, we inferred that the flat surface problem could be significantly mitigated by searching over a wide range of initial values. Back-calculation using a wide range of initial values yields BFPs similar to those obtained from single-sized-feed breakage tests (SSFBTs) up to four-dimensional parameter spaces. Therefore, by searching over a wide range of initial values, the feasibility of the back-calculation approach can be significantly improved with a minimum number of SSFBTs.

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