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1

Dr., R.Satyaprasad1, Kiran2 Ch.Surya, and G.Krishna Mohan3 Dr. "MODIFIED GENETIC ALGORITHM BASED SOFTWARE RELIABILITY USING SPRT: RAYLEIGH MODEL." International Journal of Engineering Technologies and Management Research 5, no. 4 (2018): 17–25. https://doi.org/10.5281/zenodo.1244675.

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In Classical Hypothesis testing volumes of data is to be collected and then the conclusions are drawn, which may need more time. But, Sequential Analysis of Statistical science could be adopted in order to decide upon the reliability or unreliability of the developed software very quickly. The procedure adopted for this is, Sequential Probability Ratio Test (SPRT). It is designed for continuous monitoring. The likelihood based SPRT proposed by Wald is very general and it can be used for many different probability distributions. In the present paper we propose the performance of SPRT on 6 data sets of Time domain data using Rayleigh model and analyzed the results. The parameters are estimated using Modified Genetic Algorithm.
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2

Satyaprasad, R., Surya Kiran, and G. Krishna Mohan. "MODIFIED GENETIC ALGORITHM BASED SOFTWARE RELIABILITY USING SPRT: RAYLEIGH MODEL." International Journal of Engineering Technologies and Management Research 5, no. 4 (2020): 17–25. http://dx.doi.org/10.29121/ijetmr.v5.i4.2018.204.

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In Classical Hypothesis testing volumes of data is to be collected and then the conclusions are drawn, which may need more time. But, Sequential Analysis of Statistical science could be adopted in order to decide upon the reliability or unreliability of the developed software very quickly. The procedure adopted for this is, Sequential Probability Ratio Test (SPRT). It is designed for continuous monitoring. The likelihood based SPRT proposed by Wald is very general and it can be used for many different probability distributions. In the present paper we propose the performance of SPRT on 6 data sets of Time domain data using Rayleigh model and analyzed the results. The parameters are estimated using Modified Genetic Algorithm.
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3

K, Joseph Shibu, K. Shankar, Ch Kanna Babu, and Girish K. Degaonkar. "Multi-objective optimisation of a small aircraft turbine engine rotor system with self-updating Rayleigh damping model and frequency-dependent bearing-pedestal model." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 16 (2019): 5710–23. http://dx.doi.org/10.1177/0954406219851531.

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A self-updating Rayleigh damping model and frequency-dependent bearing-pedestal model for multi-objective optimisation is presented through this paper and is applied for a small turbine engine rotor system for aircraft application. This engine is used as an auxiliary power unit on aircraft. The Rayleigh damping model and frequency-dependent bearing pedestal model are verified by carrying out experiments on this auxiliary power unit rotor system. The novel self-updating feature calculates the Rayleigh damping coefficients and frequency-dependent bearing-pedestal stiffness for each chromosome and modifies rotor system equation of motion for computing the objectives during multi-objective optimisation for each chromosome. This novel model is used for multi-objective optimisation of auxiliary power unit rotor system. The unbalance response and weight are minimised subjected to critical speed constraint. Controlled elitist genetic algorithm is used for the optimisation resulting in Pareto optimal solutions and the acceptable solution is identified as the solution close to Utopia point. The results are compared with the constant Rayleigh damping model. The new model has produced an accurate optimum solution superior to constant Rayleigh damping model.
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Xing, Zhen, and Alfredo Mazzotti. "Two-grid full-waveform Rayleigh-wave inversion via a genetic algorithm — Part 1: Method and synthetic examples." GEOPHYSICS 84, no. 5 (2019): R805—R814. http://dx.doi.org/10.1190/geo2018-0799.1.

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When reliable a priori information is not available, it is difficult to correctly predict near-surface S-wave velocity models from Rayleigh waves through existing techniques, especially in the case of complex geology. To tackle this issue, we have developed a new method: two-grid genetic-algorithm Rayleigh-wave full-waveform inversion (FWI). Adopting a two-grid parameterization of the model, the genetic algorithm inverts for unknown velocities and densities at the nodes of a coarse grid, whereas the forward modeling is performed on a fine grid to avoid numerical dispersion. A bilinear interpolation brings the coarse-grid results into the fine-grid models. The coarse inversion grid allows for a significant reduction in the computing time required by the genetic algorithm to converge. With a coarser grid, there are fewer unknowns and less required computing time, at the expense of the model resolution. To further increase efficiency, our inversion code can perform the optimization using an offset-marching strategy and/or a frequency-marching strategy that can make use of different kinds of objective functions and allows for parallel computing. We illustrate the effect of our inversion method using three synthetic examples with rather complex near-surface models. Although no a priori information was used in all three tests, the long-wavelength structures of the reference models were fairly predicted, and satisfactory matches between “observed” and predicted data were achieved. The fair predictions of the reference models suggest that the final models estimated by our genetic-algorithm FWI, which we call macromodels, would be suitable inputs to gradient-based Rayleigh-wave FWI for further refinement. We also explored other issues related to the practical use of the method in different work and explored applications of the method to field data.
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Nagai, K., A. O'Neill, Y. Sanada, and Y. Ashida. "Genetic Algorithm Inversion of Rayleigh Wave Dispersion from CMPCC Gathers Over a Shallow Fault Model." Journal of Environmental & Engineering Geophysics 10, no. 3 (2005): 275–86. http://dx.doi.org/10.2113/jeeg10.3.275.

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6

Wirawan, Rezki, Jamhir Safani, and Al Rubaiyn. "Multiple inversions of Rayleigh wave dispersion curve for geotechnical site characterization using particle swarm optimization dan genetic algorithm." Journal of Physics: Theories and Applications 7, no. 2 (2023): 201. http://dx.doi.org/10.20961/jphystheor-appl.v7i2.79065.

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The inversion of the Rayleigh wave dispersion curve is a crucial step in the multi-channel analysis of surface waves (MASW) method, used to obtain the shear wave velocity (<em>Vs</em>) profile. The nonlinear and multimodal nature of the dispersion curve makes a global optimization approach, such as particle swarm optimization (PSO) and genetic algorithm (GA), the optimal choice for inversion. This study aims to compare the performance of multiple inversions of PSO (MI-PSO) and multiple inversions of GA (MI-GA) in solving the inversion problem of the Rayleigh wave dispersion curve. The test results indicate that the utilized MI-PSO outperforms MI-GA in terms of computational time and accuracy of the obtained model
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Zhang, Jian Lin, Zhi Hong, Qian Lin, and Jie Sheng Jiang. "A Mixed Control System of 3D High Rise Benchmark Building Model Based on Genetic Algorithm." Advanced Materials Research 163-167 (December 2010): 2862–67. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2862.

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In the former research, the Damper control system, TMD control system and the Mixed Control of the active control and passive control were all optimized alone. It is found that less research of the optimization is on the Mixed Control of the Damper system and TMD system. In order to achieve better control effect, we venture to propose a Mixed Control system of third-generation three-dimensional 20-storey Benchmark model under the multi-directional earthquake in this paper. By means of Rayleigh damping and D-value, dynamic equations including the damping matrixes, stiffness matrixes of the structure are obtained. Then in the process of the optimization, the displacement reducing coefficient (DRF) is used as the objective function to optimize the placement of damping devices and control parameters based on Genetic Algorithm (GA). Numerical results in this paper show that the optimal design method proposed in this paper is effective and flexible. It can obviously reduce the seismic responses of building structure.
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8

Łabędzki, Paweł. "Fractional Kelvin–Voigt Model for Beam Vibrations: Numerical Simulations and Approximation Using a Classical Model." Electronics 14, no. 10 (2025): 1918. https://doi.org/10.3390/electronics14101918.

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In this study, a cantilever beam with a tip mass under base excitation was analyzed, with system damping modeled using a fractional derivative approach. By applying the Rayleigh–Ritz method, the governing equation was decomposed into spatial and temporal components. Analytical solutions for the temporal equation were derived; however, their complexity posed challenges for practical application. To address this, convergence acceleration techniques were employed to efficiently evaluate slowly converging series representations. Additionally, two methods for identifying the parameters of a classical model approximating the fractional system were investigated: a geometric approach based on waveform shape analysis and an optimization procedure utilizing a genetic algorithm. The identified harmonic oscillator reproduced the dynamic response of the fractional model with an average relative error typically below 5% for off-resonance excitation. Overall, the study presents a robust analytical framework for solving fractional-order vibration problems and demonstrates effective strategies for their approximation using classical harmonic models.
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Song, Zhenghong, Xiangfang Zeng, and Clifford H. Thurber. "Surface-wave dispersion spectrum inversion method applied to Love and Rayleigh waves recorded by distributed acoustic sensing." GEOPHYSICS 86, no. 1 (2021): EN1—EN12. http://dx.doi.org/10.1190/geo2019-0691.1.

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Recently, distributed acoustic sensing (DAS) has been applied to shallow seismic structure imaging providing dense spatial sampling at a relatively low cost. DAS on a standard straight fiber-optic cable mostly records axial dynamic strain, which makes it difficult to separate the Rayleigh and Love wavefields. As a result, the mixed Rayleigh and Love wave signals cannot be used in the conventional surface-wave dispersion inversion method. Therefore, it is often ensured that the source and the cable are in the same line and only Rayleigh wave dispersion is used, which limits the constraints on structure and model resolution. We have inverted surface-wave dispersion spectra instead of dispersion curves. This inversion method can use mixed Rayleigh and Love waves recorded when the source and receiver array are not aligned. The multiple-channel records are transformed to the frequency domain, and a slant stack method is used to construct the dispersion spectra. The genetic algorithm method is used to obtain an optimal S-wave velocity model that minimizes the difference between theoretical and observed dispersion spectra. A series of synthetic tests are conducted to validate our method. The results suggest that our method not only improves the flexibility of the acquisition system design, but the Love wave data also provide additional constraints on the structure. Our method is applied to the active source and ambient noise data sets acquired at a geothermal site and provides consistent results for different data sets and acquisition geometries. The sensitivity of the dispersion spectra to layer thickness, density, and P-wave velocity is also discussed. With our method, the amount of usable data can be increased, helping deliver better subsurface images.
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Xing, Zhen, and Alfredo Mazzotti. "Two-grid full-waveform Rayleigh-wave inversion via a genetic algorithm — Part 2: Application to two actual data sets." GEOPHYSICS 84, no. 5 (2019): R815—R825. http://dx.doi.org/10.1190/geo2018-0800.1.

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We have applied our two-grid genetic-algorithm Rayleigh-wave full-waveform inversion (FWI) to two actual data sets acquired in Luni (Italy) and Grenoble (France), respectively. Because our technique used 2D elastic finite-difference modeling for solving the forward problem, the observed data were 3D to 2D corrected prior to the inversion. To limit the computing time, both inversions focused on predicting low-resolution, smooth models by using quite coarse inversion grids. The wavelets for FWI were estimated directly from the observed data by using the Wiener method. In the Luni case, due to the strong dispersion effects on the data, to strengthen the inversion, envelopes and waveforms were considered in the objective function and an offset-marching strategy was applied. Though no a priori information was exploited, the outcomes of the Luni and Grenoble data inversion were fair. The predicted Luni [Formula: see text] model indicates a strong velocity increase from approximately 3 to 6 m, and velocity inversions have been detected at approximately 2 and 9 m depths. Analyzing the dispersion spectra, it results that the predicted Luni data reasonably reproduced the waveforms related to the fundamental mode and, likely, a small part of those related to the first higher mode. Concerning the Grenoble example, the predicted [Formula: see text] model coincides reasonably well with the long-wavelength structures presented in the [Formula: see text] profiles obtained from nearby boreholes. The data reconstruction is generally satisfactory, and when mismatches occur between the predicted and observed traces, the phase differences are always within half-periods. The fair inversion outcomes suggest that the predicted Luni and Grenoble models would likely be adequate initial models for local FWI, which could further increase the resolution and the details of the estimated [Formula: see text] models.
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Hasheminejad, Seyyed M., and Rezgar Shakeri. "Active Transient Acousto-Structural Response Control of a Smart Cavity-Coupled Circular Plate System." Archives of Acoustics 42, no. 2 (2017): 273–86. http://dx.doi.org/10.1515/aoa-2017-0030.

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Abstract The transient vibroacoustic response suppression of a piezo-coupled sandwich circular plate backed by a rigid-walled cylindrical acoustic enclosure is investigated. Problem formulation is based on the linear acoustic wave theory, Kirchhoff thin plate model, fluid/structure compatibility relations, Rayleigh integra formula, and active damping control (ADC) strategy. Matlab’s Genetic Algorithm (GA) is utilized to identify and optimize the feedback controller gain parameter based on a multi-objective performance index function. Durbin’s numerical Laplace inversion scheme is then used to calculate the key acousto-structural response parameters due to a transverse impulsive shock force for selected cavity depths. Numerical simulations demonstrate satisfactory performance of adopted control methodology in effective suppression of panel displacement response and radiated external sound pressure for enclosures of shallow and moderate depths. Limiting cases are considered and accuracy of the proposed model is rigorously verified.
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12

Yang, Haosen, Huirong Li, and Hui Zheng. "A structural-acoustic optimization of two-dimensional sandwich plates with corrugated cores." Journal of Vibration and Control 23, no. 18 (2016): 3007–22. http://dx.doi.org/10.1177/1077546315625558.

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This paper presents an optimization study of sandwich plates with corrugated cores for minimizing the transmitted sound power, considering the manufacturability of the structure and constraints on the structural weight and fundamental frequency. A two-dimensional plate model is developed based on the spectral element method (SEM) for the calculation of the frequency-domain vibration response of the whole sandwich structure subject to airborne excitation, and the Rayleigh integral formula is used to calculate the transmitted sound power via its structure-born path. A genetic algorithm-based multi-parameter optimization method is employed to search for the optimal structural parameters with the objective to minimize the sound power transmitted. It is indicated that the optimization results depend highly on the properties of resonant modes in the targeted frequency band. Because of the local modes of the sandwich structure in the high frequency band, the transmitted sound power can be significantly reduced with neither increasing the structural weight nor deteriorating the bending stiffness.
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13

Fu, Yu, Angen Yang, Zhenan Yao, et al. "Inversion of Rayleigh Wave Dispersion Curves via Long Short-Term Memory Combined with Particle Swarm Optimization." Computational Intelligence and Neuroscience 2022 (December 23, 2022): 1–15. http://dx.doi.org/10.1155/2022/2640929.

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An essential step in surface wave exploration is the inversion of dispersion curves. By inverting dispersion curves, we can effectively establish the shear-wave velocity model and obtain reliable subsurface stratigraphic information. The inversion of dispersion curves is an inversion problem with multiple parameters and multiple poles, and obtaining a high precision solution is difficult. Among the methods of inversion of dispersion curves, local search methods are prone to fall into local extremes, and global search methods such as particle swarm optimization (PSO) and genetic algorithm (GA) present the disadvantages of slow convergence speed and low precision. Deep learning models with strong nonlinear mapping capability can effectively solve nonlinear problems. Therefore, we propose a method called PSO-optimized long short-term memory (LSTM) network (PSO-LSTM) to invert the dispersion curves in order to improve the effect of inversion of dispersion curves. The method is based on the LSTM network, and PSO is used to optimize the LSTM network structure and other parameters that need to be given manually to improve the prediction of the network. Two theoretical geological models are used in the paper: Model A and Model B to test the PSO-LSTM. The tests include the noisy data test and noise-free data test. Model A was tested without noise, and Model B was tested with noise. In addition, PSO and LSTM were tested on model A to compare the performance of PSO-LSTM. In Model A, the maximum relative errors of PSO and LSTM are 20.76% and 5.85%, respectively, and the maximum standard deviations of PSO and LSTM are 57.37 and 1.97, respectively. For PSO-LSTM, the maximum relative errors of Model A and Model B in the inverse results are 2.05% and 2.09%, and the maximum standard deviations of Model A and Model B in the inverse results are 1.23 and 3.87, respectively. The test results of Model A show that the inversion performance of PSO-LSTM is better than those of LSTM and PSO, and the performance of the network can be improved after PSO is used to optimize the network parameters. The inverse results from Model B show that the PSO-LSTM is robust and can invert the dispersion curves well even after adding noise to the model. Finally, the PSO-LSTM is used to invert the actual data from Wyoming, USA, which demonstrates that the PSO-LSTM can be used for the quantitative interpretation of Rayleigh wave dispersion curves.
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Koroglu, Tahsin, and Elanur Ekici. "A Comparative Study on the Estimation of Wind Speed and Wind Power Density Using Statistical Distribution Approaches and Artificial Neural Network-Based Hybrid Techniques in Çanakkale, Türkiye." Applied Sciences 14, no. 3 (2024): 1267. http://dx.doi.org/10.3390/app14031267.

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In recent years, wind energy has become remarkably popular among renewable energy sources due to its low installation costs and easy maintenance. Having high energy potential is of great importance in the selection of regions where wind energy investments will be made. In this study, the wind power potential in Çanakkale Province, located in the northwest of Türkiye, is examined, and the wind speed is estimated using hourly and daily data over a one-year period. The data, including 12 different meteorological parameters, were taken from the Turkish State Meteorological Service. The two-parameter Weibull and Rayleigh distributions, which are the most widely preferred models in wind energy studies, are employed to estimate the wind power potential using hourly wind speed data. The graphical method is implemented to calculate the shape (k) and scale (c) parameters of the Weibull distribution function. Daily average wind speed estimation is performed with artificial neural network–genetic algorithm (ANN-GA) and ANN–particle swarm optimization (ANN-PSO) hybrid approaches. The proposed hybrid ANN-GA and ANN-PSO algorithms provide correlation coefficient values of 0.94839 and 0.94042, respectively, indicating that the predicted and measured wind speed values are notably close. Statistical error indices reveal that the ANN-GA model outperforms the ANN-PSO model.
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Talebitooti, Roohollah, Hamed Darvish Gohari, Mohamadreza Zarastvand, and Ali Loghmani. "A robust optimum controller for suppressing radiated sound from an intelligent cylinder based on sliding mode method considering piezoelectric uncertainties." Journal of Intelligent Material Systems and Structures 30, no. 20 (2019): 3066–79. http://dx.doi.org/10.1177/1045389x19873412.

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In this study, a robust controller against the uncertainties in piezoelectric patches including sensor and actuator is designed based on sliding mode method to control the radiated sound from cylindrical shells. Accordingly, in order to extract and discretize the dynamic equations of a smart cylinder equipped with piezoelectric patches, the Hamilton’s principle and the Rayleigh-Ritz method are, respectively, used . The radiated sound is estimated by the Kirchhoff-Helmholtz integral and the acoustic structural sensing method. Furthermore, an innovative approach is proposed on sliding mode control to model system uncertainties and design robust control signals against these disturbances. Using effective control signals for each mode is the applied methodology for establishing independent sliding surfaces. In fact, it is attempted to relate between actuator matrix determinant and system control ability in generating the efficient control signals and error reduction due to actuators uncertainties. By the aid of this relation, optimization of the actuators position according to the genetic algorithm is implemented. The obtained results show that by optimizing the actuators position not only the appropriate performance of the system in controlling the radiated sound from the structure is enhanced but also the essential control voltage for each actuator is significantly decreased.
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Luo, Wei, Renhu Li, Fang Shen, and Jianqiang Liu. "HY-1C/D CZI Image Atmospheric Correction and Quantifying Suspended Particulate Matter." Remote Sensing 15, no. 2 (2023): 386. http://dx.doi.org/10.3390/rs15020386.

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HY-1C/D both carry a coastal zone imager (CZI) with a spatial resolution of 50 m and a swath width of 950 km, two observations can be achieved in three days when two satellites operating in a network. Accurate atmospheric correction is the basis for quantitative inversion of ocean color parameters using CZI However, atmospheric correction in estuarine and coastal waters with complex optical properties is a challenge due to the band setting of CZI. This paper proposed a novel atmospheric correction algorithm for CZI images applicable to turbid waters in estuarine and coastal zone. The Rayleigh scattering reflectance of CZI was calculated based on a vector radiative transfer model. Next, a semi-empirical radiative transfer model with suspended particle concentration as the parameter is used to model the water-atmosphere coupling. Finally, the parameters of the coupling model are solved by combining a global optimization method based on a genetic algorithm. The results indicate that the CZI-derived remote-sensing reflectance (Rrs) are in good agreement with the quasi-synchronous Landsat-8/9 operational land imager (OLI) derived Rrs in the green and red bands (R2 > 0.96). Validation using in situ data revealed that the RMSE of the CZI-derived Rrs in the green and red bands was 0.0036 sr−1 and 0.0035 sr−1. More importantly, the values and spatial distributions of suspended particulate matter (SPM) estimated by CZI and those estimated by OLI in the Subei Shoal and the Yangtze River Estuary are basically consistent, and the validation using in situ data revealed that the inversion of SPM concentration by CZI was effective (R2 = 0.86, RMSE = 0.0362 g/L), indicating that CZI has great potential and broad application prospects for monitoring the spatial and temporal dynamics of SPM in estuarine and coastal waters. The study results will lay the foundation for further estimating suspended sediment fluxes and carbon fluxes, thus providing data support and scientific basis for promoting resource development, utilization and conservation strategies in estuarine and coastal areas.
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Sun, Ruijun, Changsheng Zheng, Fazhan Yang, Jingjing Zhang, Yuesong Zhou, and Xiang Li. "Dynamic analysis of porous fiber‐reinforced sandwich composite panel with variable angle." Polymer Composites, January 12, 2025. https://doi.org/10.1002/pc.29497.

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AbstractDamped sandwich composite structures are increasingly used in the aerospace, automotive and energy sectors due to their high damping and lightweight properties. Here, a novel porous fiber‐reinforced sandwich composite structure is proposed, by punching holes in fiber cloth with impregnated damping solution, and resin flows through the holes during the formation of the composite structure, connecting the upper and lower prepreg layers. This paper focuses on the theoretical study of the free vibration behavior of simply supported composite porous multilayer fiber‐reinforced sandwich composite structures with arbitrary delamination angles. The vibrational differential equation including the orientation angle was established and solved using Rayleigh‐Ritz method and Navier method. Subsequently, the Abaqus finite element method and modal test analysis were used to evaluate the dynamic performance of the structure with different orientation angles, verify the proposed theoretical model and solution strategy, and perform structural optimization based on a genetic algorithm. The results show that the panel with the area ratio of the damping layer of 94.854% and a fiber orientation angle of multiples of 45° has excellent dynamic performance. This model has significant advantages in improving structural stiffness and provides a theoretical basis for practical engineering applications.Highlights A dynamic model of porous multilayer damping plate is established. The effect of different fiber orientation angle on porous plate is studied. An experimental platform is constructed to corroborate the theoretical accuracy. Structural optimization of porous plate is conducted using a genetic algorithm. The influence of structural parameters on the porous plate is analyzed.
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18

Najimi, Maryam. "Securing Intelligent Reflecting Surface (IRS)–Aided NOMA Networks in Covert Wireless Communication Using Jammer." International Journal of Communication Systems 38, no. 9 (2025). https://doi.org/10.1002/dac.70108.

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ABSTRACTIn this paper, an intelligent reflecting surface (IRS)–assisted non‐orthogonal multiple access (NOMA) network is proposed in a multi‐user scenario where the transmitter communicates with its receiver covertly by helping a friendly jammer. In this network, an adversary detects the communication existence of the users in the frequency band while the jammer sends the jamming signals to the adversary to degrade its performance. In this case, the analytical expressions for the secrecy outage probability (SOP), false alarm probability, and the missed detection probability at adversary are obtained. Rayleigh fading channel is assumed as the channel model while the covert communication performance is improved. For this purpose, the total effective rates are maximized by optimization of the transmission power, power allocation to multiple users, IRS reflection matrix, and also transmission probability adjustment with constraints on the detection performance and SOP. The problem is non‐convex; therefore, we present the genetic algorithm (GA) method to find the suboptimal solution for the problem with lower complexity. Numerical results show the performance improvement of the proposed algorithm in comparison to the benchmark algorithms.
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Jamshidi, Hamed, and Ali A Jafari. "Predicting unbalance asymmetric rotor vibration behavior based on sensitivity analysis and using Response Surface Methodology method considering parallel misalignment." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, July 19, 2021, 095440622110145. http://dx.doi.org/10.1177/09544062211014545.

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Mass unbalance, shaft misalignment, rotor asymmetry, and force due to rotor weight are the main causes of vibrations in rotary machines especially when the shaft is not symmetric. Although extensive researches have been carried out to determine the effect of each on the increase of vibration levels far, there has been no clear study on the simultaneous existence of all these parameters and their interactions. In this research, the model is a rotor composed of a rigid disk and a flexible asymmetric shaft. The general equations of motion are first derived by considering the effect of high order large deformation in bending. The equations are discretized using the Rayleigh–Ritz method. The obtained equations are nonlinear coupled differential equations that are solved using the numerical method. Sensitivity analysis has been utilized to identify the percentage of the contribution of each parameter to the increase of vibration. Then a DOE-based Response Surface Methodology (RSM) is applied to present a model to predict the vibration behavior of the system with good accuracy. Genetic algorithm is also used to optimize the effective parameters and to verify the results. A 3D model of the asymmetric rotor is carried out in experimental studies to attain more precise responses. The research shows that rotor asymmetry alone and also its combination with gravitational force has much more effects on the vibration amplitude. These effects are observed at frequencies both once and twice the rotational speed in spectral data, in comparison with other factors. The mass unbalance also plays a significant role in frequency equal to the rotational speed. In the end, the achieved results are validated with experimental simulations.
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Pan, QiAn, Xuzhang Shen, Xiuwei Ye, and Liwei Wang. "Fine Shear-Wave Velocity Structures of Subsurface beneath the Guangdong–Hong Kong–Macao Greater Bay Area with Dense Seismic Array and SPAC Method." Seismological Research Letters, May 13, 2024. http://dx.doi.org/10.1785/0220230310.

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Abstract We apply the spatial autocorrelation (SPAC) method to construct the 3D subsurface shear-wave velocity structure model using the short-period dense seismic array (containing 725 nodal geophones) located at the Guangdong–Hong Kong–Macao Greater Bay area (GBA). We first divided the dense array into numerous subarrays, with each subarray consisting of nine nodal geophones, and obtained 562 subarrays that can provide 1D VS profiles of the same quantity. Then, the SPAC method and genetic algorithm are utilized to extract the dispersion curve of the Rayleigh wave from the raw microtremor data and invert VS structure, respectively. Finally, a 3D VS structure model from the surface to 3.3 km depth is derived by combining all 1D VS structures. Relatively low-velocity anomalies above 700 m are considered unconsolidated shallow sediments as well as relatively high-velocity anomalies beneath 1100 m are attributed to consolidated granite bedrock. Meanwhile, low-velocity anomalies that are identified through the vertical VS profile at a depth of about 900–3000 m can be contributed to the fractured zone, and striped low-velocity anomalies in the horizontal VS maps reveal the location of the deeply buried faults in the study area. The results also mean that the SPAC method combined with the records of short-period dense seismic array can be effectively applied to image subsurface structures in high-populated urban area. The development of this noise-resistance and environment-friendly geophysical technique provides a reliable and effective way to explore the complicated subsurface geological structures, which is of great significance to urban engineering construction and earthquake disaster reduction work in densely populated urban agglomerations.
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