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Journal articles on the topic 'Root-mean-square fluctuation'
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1
Cai, Jian-Cheng, Hao-Jie Chen, Volodymyr Brazhenko, and Yi-Hong Gu. "Study of the Hydrodynamic Unsteady Flow Inside a Centrifugal Fan and Its Downstream Pipe Using Detached Eddy Simulation." Sustainability 13, no. 9 (May 2, 2021): 5113. http://dx.doi.org/10.3390/su13095113.
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The detailed unsteady turbulent flow inside a centrifugal fan and its downstream pipe was studied using detached eddy simulation (DES) at three flowrates, namely, the best efficiency point (BEP), 0.75BEP, and 1.49BEP. Both the mean and fluctuating flow fields were analyzed on the basis of the root-mean-square value as the indication of fluctuating intensity. Results showed that the pressure fluctuation had the minimum value at BEP, but the velocity fluctuation increased with the flowrate. Most regions inside the centrifugal fan underwent large pressure fluctuation with the magnitude of about 10~20% of pref = 0.5 ρu22, where u2 is the blade velocity at the impeller outlet. The pressure fluctuation had a maximum value at the impeller side of the tongue tip rather than the stagnation point, and it decreased rapidly along the outlet pipe with magnitude about 1% of pref after distance of five pipe diameters. The spectra of hydrodynamic pressure showed conspicuous spikes at the blade passing frequency (BPF) in the volute but not in the downstream pipe. At the downstream pipe entrance, pressure fluctuation spectra agreed with experimental results, showing that hydrodynamic pressure fluctuations were dominant; however, the experimental data showed a much slower decreasing rate due to the acoustic fluctuations.
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Lu, Tao, Su Mei Liu, Ping Wang, and Wei Yyu Zhu. "Larger-Eddy Simulation of Velocity Fluctuation in a Mixing T-Junction." Applied Mechanics and Materials 152-154 (January 2012): 1313–18. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1313.
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Velocity fluctuations in a mixing T-junction were simulated in FLUENT using large-eddy simulation (LES) turbulent flow model with sub-grid scale (SGS) Smagorinsky–Lilly (SL) model. The normalized mean and root mean square velocities are used to describe the time-averaged velocities and the velocities fluctuation intensities. Comparison of the numerical results with experimental data shows that the LES model is valid for predicting the flow of mixing in a T-junction junction. The numerical results reveal the velocity distributions and fluctuations are basically symmetrical and the fluctuation at the upstream of the downstream of the main duct is stronger than that at the downstream of the downstream of the main duct.
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Suzuki, Y., M. Kiya, T. Sampo, and Y. Naka. "Pressure Fluctuations on the Surface of a Hemisphere Immersed in a Thick Turbulent Boundary Layer." Journal of Fluids Engineering 109, no. 2 (June 1, 1987): 130–35. http://dx.doi.org/10.1115/1.3242632.
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Statistical properties of pressure fluctuations on the surface of a hemisphere immersed in a thick turbulent boundary layer are described. The height of the hemisphere tested was 0.275 thicknesses of the boundary layer. Reynolds number based on the model diameter D and the time-mean approaching flow velocity at the level of the top Ur was 3.0 × 105. Time-mean and root-mean-square (rms) values, probability density and power spectra of the pressure fluctuations are presented and discussed. The pressure fluctuations are related to the fluctuating approaching-flow velocity in terms of the pressure-velocity admittance and the cross correlation. Main results are that the time-mean and rms pressures attained a primary maximum at the front stagnation point; that the pressure-velocity admittance near the front stagnation point was approximately unity at frequencies less than about 0.4 Ur/D; that the pressure fluctuation in front of the hemisphere is positively correlated with that in the rear side and negatively correlated with that in the middle.
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Tsekov, Roumen. "Brownian Emitters." Fluctuation and Noise Letters 15, no. 04 (September 29, 2016): 1650022. http://dx.doi.org/10.1142/s021947751650022x.
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A Brownian harmonic oscillator, which dissipates energy either by friction or via emission of electromagnetic radiation, is considered. This Brownian emitter is driven by the surrounding thermo-quantum fluctuations, which are theoretically described by the fluctuation–dissipation theorem. It is shown how the Abraham–Lorentz force leads to dependence of the half-width on the peak frequency of the oscillator amplitude spectral density. It is found that for the case of a charged particle moving in vacuum at zero temperature, its root-mean-square velocity fluctuation is a universal constant, equal to roughly 1/18 of the speed of light. The relevant Fokker–Planck and Smoluchowski equations are also derived.
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Li, Yuepeng, Liuyue Wang, Xun Zou, Jihong Qu, and Gang Bai. "Experimental and Simulation Research on the Process of Nitrogen Migration and Transformation in the Fluctuation Zone of Groundwater Level." Applied Sciences 12, no. 8 (April 8, 2022): 3742. http://dx.doi.org/10.3390/app12083742.
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The fluctuation of groundwater causes a change in the groundwater environment and then affects the migration and transformation of pollutants. To study the influence of water level fluctuations on nitrogen migration and transformation, physical experiments on the nitrogen migration and transformation process in the groundwater level fluctuation zone were carried out. A numerical model of nitrogen migration in the Vadose zone and the saturated zone was constructed by using the software HydrUS-1D. The correlation coefficient and the root mean square error of the model show that the model fits well. The numerical model is used to predict nitrogen migration and transformation in different water level fluctuation scenarios. The results show that, compared with the fluctuating physical experiment scenario, when the fluctuation range of the water level increases by 5 cm, the fluctuation range of the nitrogen concentration in the coarse sand, medium sand and fine sand media increases by 37.52%, 31.40% and 21.14%, respectively. Additionally, when the fluctuation range of the water level decreases by 5 cm, the fluctuation range of the nitrogen concentration in the coarse sand, medium sand and fine sand media decreases by 36.74%, 14.70% and 9.39%, respectively. The fluctuation of nitrogen concentration varies most significantly with the amplitude of water level fluctuations in coarse sand; the change in water level has the most significant impact on the flux of nitrate nitrogen and has little effect on the change in nitrite nitrogen and ammonium nitrogen, and the difference in fine sand is the most obvious, followed by medium sand, and the difference in coarse sand is not great.
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Saavedra, L. G. P. "Geometric Factors in Electromagnetic Field Commutators and the Quantum Information Control of Vacuum Fluctuations." Open Systems & Information Dynamics 14, no. 03 (September 2007): 319–32. http://dx.doi.org/10.1007/s11080-007-9055-1.
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The electromagnetic field commutation relations are defined in terms of geometric factors that are double averages over two finite four-dimensional space-time regions. The square root of any of the uncertainty relations derived from the aforementioned commutators is taken as a critical field, in the sense that any electromagnetic field much larger than it can be treated as classical. Another critical electromagnetic field associated with the quantum information control of vacuum fluctuations can be chosen as the square root of the mean quadratic fluctuation of each quantity of electromagnetic field, when the number of photons is defined and is equal to zero. Any electromagnetic field expectation value could be measured if it is much greater than the last critical field. This article covers a magnitude order comparison between the critical fields and its consequences for measuring the electromagnetic field information.
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Cho, Soo-Hwan, and Sang-Gyun Kang. "Application of the Combined Kalman Filter and Root-Mean-Square Method to Detection of Voltage Fluctuation." Advanced Science Letters 8, no. 1 (April 15, 2012): 649–53. http://dx.doi.org/10.1166/asl.2012.2457.
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Kysela, Bohuš, Jiří Konfršt, Ivan Fořt, Michal Kotek, and Zdeněk Chára. "Study of the Turbulent Flow Structure around a Standard Rushton Impeller." Chemical and Process Engineering 35, no. 1 (March 1, 2014): 137–47. http://dx.doi.org/10.2478/cpe-2014-0010.
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Abstract The velocity field around the standard Rushton turbine was investigated by the Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) measurements. The mean ensembleaveraged velocity profiles and root mean square values of fluctuations were evaluated at two different regions. The first one was in the discharge stream in the radial direction from the impeller where the radial flow is dominant and it is commonly modelled as a swirling turbulent jet. The validity range of the turbulent jet model was studied. The second evaluated region is under the impeller where flow seems to be at first sight rather rigorous but obtained results show nonnegligible values of fluctuation velocity.
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Spangler, S. R. "The small amplitude of density turbulence in the inner solar wind." Nonlinear Processes in Geophysics 10, no. 1/2 (April 30, 2003): 113–20. http://dx.doi.org/10.5194/npg-10-113-2003.
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Abstract. Very Long Baseline Interferometer (VLBI) observations were made of radio sources close to the Sun, whose lines of sight pass through the inner solar wind (impact parameters 16-26 RE). Power spectra were analyzed of the interferometer phase fluctuations due to the solar wind plasma. These power spectra provide information on the level of plasma density fluctuations on spatial scales of roughly one hundred to several thousand kilometers. By specifying an outer scale to the turbulence spectrum, we can estimate the root-mean-square (rms) amplitude of the density fluctuations. The data indicate that the rms fluctuation in density is only about 10% of the mean density. This value is low, and consistent with extrapolated estimates from more distant parts of the solar wind. Physical speculations based on this result are presented.
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Lu, Tao, Yong Wei Wang, and Ping Wang. "Large Eddy Simulation with Three Kinds of Sub-Grid Scale Model on Temperature Fluctuation of Hot and Cold Fluids Mixing in a Tee." Applied Mechanics and Materials 152-154 (January 2012): 1307–12. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1307.
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In the present work the temperature fluctuations in a mixing tee were simulated on FLUENT platform using the large-eddy simulation (LES) turbulent flow model with three kinds of sub-grid scale (SGS) models such as Smagorinsky-Lilly (SL) model, Wall-adapted Local Eddy-viscosity (WALE) model, and Kinetic-energy transport (KET) model. The normalized mean and root mean square temperatures were predicted and analyzed with consideration of buoyancy. The numerical results showed that buoyancy greatly influences the mixing flow and the thermal striping phenomena were quite obvious. These three SGS models have somewhat similar accuracies for prediction of the temperature fluctuation and thermal stripping in a tee of mixing hot and cold fluids.
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Fu, Zhengqing, Guolin Liu, Lanlan Guo, Weike Liu, and Hua Guo. "Nonlinear Least Square Based on Control Direction by Dual Method and Its Application." Mathematical Problems in Engineering 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/7094157.
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A direction controlled nonlinear least square (NLS) estimation algorithm using the primal-dual method is proposed. The least square model is transformed into the primal-dual model; then direction of iteration can be controlled by duality. The iterative algorithm is designed. The Hilbert morbid matrix is processed by the new model and the least square estimate and ridge estimate. The main research method is to combine qualitative analysis and quantitative analysis. The deviation between estimated values and the true value and the estimated residuals fluctuation of different methods are used for qualitative analysis. The root mean square error (RMSE) is used for quantitative analysis. The results of experiment show that the model has the smallest residual error and the minimum root mean square error. The new estimate model has effectiveness and high precision. The genuine data of Jining area in unwrapping experiments are used and the comparison with other classical unwrapping algorithms is made, so better results in precision aspects can be achieved through the proposed algorithm.
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Mei, Renwei, R. J. Adrian, and T. J. Hanratty. "Turbulent Dispersion of Heavy Particles With Nonlinear Drag." Journal of Fluids Engineering 119, no. 1 (March 1, 1997): 170–79. http://dx.doi.org/10.1115/1.2819104.
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The analysis of Reeks (1977) for particle dispersion in isotropic turbulence is extended so as to include a nonlinear drag law. The principal issue is the evaluation of the inertial time constants, βα−1, and the mean slip. Unlike what is found for the Stokesian drag, the time constants are functions of the slip velocity and are anisotropic. For settling velocity, VT, much larger than root-mean-square of the fluid velocity fluctuations, u0, the mean slip is given by VT. For VT→0, the mean slip is related to turbulent velocity fluctuation by assuming that fluctuations in βα are small compared to the mean value. An interpolation formula is used to evaluate βα and VT in regions intermediate between conditions of VT→0 and VT≫ u0. The limitations of the analysis are explored by carrying out a Monte-Carlo simulation for particle motion in a pseudo turbulence described by a Gaussian distribution and Kraichnan’s (1970) energy spectrum.
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Badshah, Syed Lal, Abdul Naeem Khan, and Yahia Nasser Mabkhot. "Molecular Dynamics Simulation of Cholera Toxin A-1 Polypeptide." Open Chemistry 14, no. 1 (January 1, 2016): 188–96. http://dx.doi.org/10.1515/chem-2016-0021.
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AbstractA molecular dynamics (MD) simulation study of the enzymatic portion of cholera toxin; cholera toxin A-1 polypeptide (CTA1) was performed at 283, 310 and 323 K. From total energy analysis it was observed that this toxin is stable thermodynamically and these outcomes were likewise confirmed by root mean square deviations (RMSD) investigations. The Cα root mean square fluctuation (RMSF) examinations revealed that there are a number of residues inside CTA1, which can be used as target for designing and synthesizing inhibitory drugs, in order to inactivate cholera toxin inside the human body. The fluctuations in the radius of gyration and hydrogen bonding in CTA1 proved that protein unfolding and refolding were normal routine phenomena in its structure at all temperatures. Solvent accessible surface area study identified the hydrophilic nature of the CTA1, and due to this property it can be a potential biological weapon. The structural identification (STRIDE) algorithm for proteins was successfully used to determine the partially disordered secondary structure of CTA1. On account of this partially disordered secondary structure, it can easily deceive the proteolytic enzymes of the endoplasmic reticulum of host cells.
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Tian, Wei, and Xin Cheng Ren. "Simulation on Composite Backscattering from Rough Surface with Target above it." Advanced Materials Research 490-495 (March 2012): 603–7. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.603.
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One-dimensional Gaussion rough surface is simulated and employed by Monte Carlo Method, the composite backscattering from one-dimensional Gaussion rough surface with rectangular cross-section column above it is studied using Method of Moment. The curves of composite backscattering coefficient with scattering angle and frequency of incident wave are simulated by numerical calculation, the influence of the root mean square and the correlation length of rough surface fluctuation, the height between the center of the rectangular cross-section column and the rough surface, the length and the width of the rectangular cross-section column is discussed. The characteristic of the composite back-scatting from one-dimensional Gaussion rough surface with a rectangular cross-section column above it is obtained. The results show that the influences of the root mean square and the correlation length of rough surface fluctuation, the height between the center of the rectangular cross-section column and the rough surface, the width of the rectangular cross-section column on the composite backscattering coefficients are obvious while the influences of the length of the rectangular cross-section column on the complex backscattering coefficient is less.
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Kasagi, N., Y. Tomita, and A. Kuroda. "Direct Numerical Simulation of Passive Scalar Field in a Turbulent Channel Flow." Journal of Heat Transfer 114, no. 3 (August 1, 1992): 598–606. http://dx.doi.org/10.1115/1.2911323.
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A direct numerical simulation (DNS) of the fully developed thermal field in a two-dimensional turbulent channel flow of air was carried out. The isoflux condition was imposed on the two walls so that the local mean temperature increased linearly in the streamwise direction. With any buoyancy effect neglected, temperature was considered as a passive scalar. The computation was executed on 1,589,248 grid points by using a spectral method. The statistics obtained were root-mean-square temperature fluctuations, turbulent heat fluxes, turbulent Prandtl number, and dissipation time scales. They agreed fairly well with existing experimental and numerical simulation data. Each term in the budget equations of temperature variance, its dissipation rate, and turbulent heat fluxes was also calculated. It was found that the temperature fluctuation θ′ was closely correlated with the streamwise velocity fluctuation u′, particularly in the near-wall region. Hence, the distribution of budget terms for the streamwise and wall-normal heat fluxes, u′θ′ and v′θ′, were very similar to those for the two Reynolds stress components, u′u′ and u′v′.
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Tang, Hsin-Chieh, and Calvin Yu-Chian Chen. "Design of Glucagon-Like Peptide-1 Receptor Agonist for Diabetes Mellitus from Traditional Chinese Medicine." Evidence-Based Complementary and Alternative Medicine 2014 (2014): 1–17. http://dx.doi.org/10.1155/2014/385120.
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Glucagon-like peptide-1 (GLP-1) is a promising target for diabetes mellitus (DM) therapy and reduces the occurrence of diabetes due to obesity. However, GLP-1 will be hydrolyzed soon by the enzyme dipeptidyl peptidase-4 (DPP-4). We tried to design small molecular drugs for GLP-1 receptor agonist from the world's largest traditional Chinese medicine (TCM) Database@Taiwan. According to docking results of virtual screening, we selected 2 TCM compounds, wenyujinoside and 28-deglucosylchikusetsusaponin IV, for further molecular dynamics (MD) simulation. GLP-1 was assigned as the control compound. Based on the results of root mean square deviation (RMSD), solvent accessible surface (SAS), mean square deviation (MSD), Gyrate, total energy, root mean square fluctuation (RMSF), matrices of smallest distance of residues, database of secondary structure assignment (DSSP), cluster analysis, and distance of H-bond, we concluded that all the 3 compounds could bind and activate GLP-1 receptor by computational simulation. Wenyujinoside and 28-deglucosylchikusetsusaponin IV were the TCM compounds that could be GLP-1 receptor agonists.
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PRECUPAS, Aurica, and Sorana IONESCU. "Exploring the interaction of 5,6- benzocoumarin-3-carboxylic acid with bovine serum albumin at the molecular level: A biophysical investigation using molecular dynamics." Revue Roumaine de Chimie 66, no. 1 (2021): 49–58. http://dx.doi.org/10.33224/rrch.2021.66.1.05.
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In this work, molecular dynamics (MD) is used to monitor the conformational space spanned by a ligand when in the binding pocket of a protein. 5,6-benzocoumarin-3-carboxylic acid was chosen as it is a relatively rigid molecule, with only one rotational degree of freedom, useful in its simplicity, whereas bovine serum albumin was used as a model protein. The initial geometry of the protein-ligand complex was obtained by molecular docking. The MD simulation was carried out for 90 ns and the dynamic evolution of the system was explored based on the usual parameters: root mean square deviation (RMSD), radius of gyration (Rg) and root mean square fluctuation (RMSF). The MD trajectory was analysed and interpreted in terms of the hydrogen bonds formed with the surrounding aminoacid residues and the conformational space spanned by the ligand during the interaction process.
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Kobayashi, Ayame, Motokuni Nakajima, Yoh Noguchi, Ryota Morikawa, Yukiko Matsuo, and Masako Takasu. "Molecular Dynamics Simulation of the Complex of PDE5 and Evodiamine." Life 13, no. 2 (February 18, 2023): 578. http://dx.doi.org/10.3390/life13020578.
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Alzheimer’s disease is an irreversible neurological disorder for which there are no effective small molecule therapeutics. A phosphodiesterase 5 (PDE5) inhibitor is a candidate medicine for the treatment of Alzheimer’s disease. Rutaecarpine, an indole alkaloid found in Euodiae Fructus, has inhibitory activity for PDE5. Euodiae Fructus contains more evodiamine than rutaecarpine. Therefore, we performed molecular dynamics simulations of the complex of PDE5 and evodiamine. The results showed that the PDE5 and (−)-evodiamine complexes were placed inside the reaction center compared to the case of PDE5 and (+)-evodiamine complex. The binding of (−)-evodiamine to PDE5 increased the root-mean-square deviation and radius of gyration of PDE5. In the PDE5 with (−)-evodiamine complex, the value of the root-mean-square fluctuation of the M-loop, which is thought to be important for activity, increased. This result suggests that (−)-evodiamine may have inhibitory activity.
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ZHANG, WEI, ZIJIAN XU, and ZHIYUAN ZHU. "STUDY OF THERMAL STABILITY OF FULLERENES BY MOLECULAR DYNAMICS." International Journal of Modern Physics B 19, no. 15n17 (July 10, 2005): 2892–98. http://dx.doi.org/10.1142/s0217979205031870.
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The thermal stability of fullerene C20, C26, C36 and C60 is studied using Molecular Dynamics (MD) simulation based on Brenner potential in this work. Lindemann's relative root-mean-square (rms) bond-length fluctuation is used to monitor the behavior of the structural and thermal properties. The results show that the rms bond-length fluctuation becomes scattered points at relative high tempereture, which is caused by different isomerization transitions. Larger fullerenes are found to be more stable than small ones. The results are compared with those from MD simulation based on TLHT potential. Mechanic stability of fullerene C20 is also studied.
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Wu, Tiecheng, Wanzhen Luo, Dapeng Jiang, Rui Deng, and Yulong Li. "Stereo Particle Image Velocimetry Measurements of the Wake Fields Behind A Panamax Bulker Ship Model Under the Ballast Condition." Journal of Marine Science and Engineering 8, no. 6 (May 30, 2020): 397. http://dx.doi.org/10.3390/jmse8060397.
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Particle image velocimetry is applied in this study to measure the wake flow field of a Panamax Bulker ship model under the ballast condition. This investigation revealed that the Froude number is 0.167. The time-averaged velocity, turbulent fluctuations, turbulent kinetic energy (TKE), Reynolds stresses, and vorticity information were measured to perform a comparison with the design condition. The time-averaged velocity contours indicated that the ballast and design conditions have distinct hook-like axial velocity contours; however, they appeared at different positions. The big difference under the ballast condition is that the top of the propeller disk area is near the free surface and a region with strong root mean square velocity fluctuation is formed near the free surface. The TKE, the Reynolds stresses, and the hub cap vortex (Hcv) are all affected by the turbulent velocity fluctuation region under the ballast condition. A strong bilge vortex (Bv) is produced when the water flows through the U-shaped stern for the design and ballast conditions.
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Ammer, Mohammed Abdullah, and Theyazn H. H. Aldhyani. "Deep Learning Algorithm to Predict Cryptocurrency Fluctuation Prices: Increasing Investment Awareness." Electronics 11, no. 15 (July 28, 2022): 2349. http://dx.doi.org/10.3390/electronics11152349.
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Digital currencies such as Ethereum and XRP allow for all transactions to be carried out online. To emphasize the decentralized nature of fiat currency, we can refer, for example, to the fact that all virtual currency users may access services without third-party involvement. Cryptocurrency price swings are non-stationary and highly erratic, similarly to the price changes of conventional stocks. Owing to the appeal of cryptocurrencies, both investors and researchers have paid more attention to cryptocurrency price forecasts. With the rise of deep learning, cryptocurrency forecasting has gained great importance. In this study, we present a long short-term memory (LSTM) algorithm that can be used to forecast the values of four types of cryptocurrencies: AMP, Ethereum, Electro-Optical System, and XRP. Mean square error (MSE), root mean square error (RMSE), and normalize root mean square error (NRMSE) analyses were used to evaluate the LSTM model. The findings obtained from these models showed that the LSTM algorithm had superior performance in predicting all forms of cryptocurrencies. Thus, it can be regarded as the most effective algorithm. The LSTM model provided promising and accurate forecasts for all cryptocurrencies. The model was applied to forecast the future closing prices of cryptocurrencies over a period of 180 days. The Pearson correlation metric was applied to assess the correlation between the prediction and target values in the training and testing processes. The LSTM algorithm achieved the highest correlation values in training (R = 96.73%) and in testing (96.09%) in predicting XRP currency prices. Cryptocurrency prices could be accurately predicted using the established LSTM model, which displayed highly efficient performance. The relevance of applying these models is that they may have huge repercussions for the economy by assisting investors and traders in identifying trends in the sales and purchases of different types of cryptocurrencies. The results of the LSTM model were compared with those of existing systems. The results of this study demonstrate that the proposed model showed superior accuracy based on the low prediction errors of the proposed system.
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Manshadi, M. D., and M. K. Esfeh. "Experimental investigation of flowfield over an iced aerofoil." Aeronautical Journal 120, no. 1227 (May 2016): 735–56. http://dx.doi.org/10.1017/aer.2016.29.
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ABSTRACTWind-tunnel measurements were used to study the characteristics of the unsteady separation bubbles on a NACA 0015 aerofoil with simulated two-dimensional leading-edge glaze ice accretions. The unsteadiness present in the iced-aerofoil flowfield was determined using measurements of the time-dependent aerofoil surface pressure distribution at Reynolds number of 1.0 × 106. Additionally, the unsteady flow features were investigated through the power spectrum of the stream-wise velocity fluctuations using a hot-wire anemometry. The results showed that the highest value of root-mean-square fluctuation of the surface pressure consistently occurred upstream of the mean shear-layer reattachment location. Spectral analysis of stream-wise velocity fluctuations near reattachment location revealed evidence of the regular frequency at Strouhal numbers of 0.5-0.63. Moreover, the low-frequency oscillations associated with shear-layer flapping was also identified in the wake velocity spectra on the order of 10 Hz that resulted in Strouhal numbers of 0.0186-021.
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Choi, Seok-Ki, and Seong-O. Kim. "Evaluation of Turbulence Models for Thermal Striping in a Triple Jet." Journal of Pressure Vessel Technology 129, no. 4 (October 29, 2006): 583–92. http://dx.doi.org/10.1115/1.2767337.
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A computational study for an evaluation of the current turbulence models for the prediction of a thermal striping in a triple jet is performed. The tested turbulence models are the two-layer model, the shear stress transport model, and the elliptic relaxation model. These three turbulence models are applied to the prediction of a thermal striping in a triple jet in which detailed experimental data are available. The predicted time-averaged and root-mean-square values of the temperature are compared with the experimental data, and the capability of predicting the oscillatory behavior of the ensemble-averaged temperature is investigated. From these works, it is shown that only the elliptic relaxation model is capable of predicting the oscillatory behavior of the ensemble-averaged temperature. It is also shown that the elliptic relaxation model predicts best the time-averaged temperature and the root mean square of the temperature fluctuation. However, this model predicts a slower mixing at the far downstream of the jet.
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Elfita, Lina, Anjas Apriadi, Supandi Supandi, and Shanifa Dianmurdedi. "Studi Penambatan Molekuler dan Simulasi Dinamika Molekuler Senyawa Turunan Furanokumarin terhadap Reseptor Estrogen Alfa (ER-α) Sebagai Anti Kanker Payudara." Jurnal Sains Farmasi & Klinis 9, no. 3 (January 27, 2023): 255. http://dx.doi.org/10.25077/jsfk.9.3.255-264.2022.
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Kanker payudara menjadi salah satu jenis kanker dengan penderita terbanyak baik di dunia maupun di Indonesia, Reseptor Estrogen Alfa (ER-α) menjadi target utama karena dapat mengatur transkripsi gen dan jalur persinyalan interseluler. Penelitian ini bertujuan untuk menganalisis afinitas dan kestabilan ikatan kompleks ligan senyawa turunan furanokumarin dengan reseptor estrogen alfa. Metode yang digunakan secara in silico atau komputasi yaitu penambatan molekuler menggunakan software AutoDock dan simulasi dinamika molekuler menggunakan software Gromacs. Hasil penambatan molekuler senyawa Bergamottin sebagai senyawa uji paling baik dengan nilai ∆G = -8,98 kkal/mol. Sedangkan ligan pembanding 4-Hydroxytamoxifen dengan nilai ∆G = -11,34 kkal/mol. Hal tersebut menunjukkan bahwa afinitas 4-Hydroxytamoxifen masih lebih baik daripada Bergamottin. Kestabilan ikatan ligan-reseptor dikonfirmasi dengan simulasi dinamika molekuler menunjukkan 4-Hydroxytamoxifen lebih stabil berikatan dengan ER-α berdasarkan parameter Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF), Radius of Gyration dan ikatan hidrogen. 4-Hydroxytamoxifen memiliki afinitas dan kestabilannya lebih baik dalam berikatan dengan reseptor estrogen alfa (ER-α)
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Fatriansyah, Jaka Fajar, Ara Gamaliel Boanerges, Syarafina Ramadhanisa Kurnianto, Agrin Febrian Pradana, Fadilah, and Siti Norasmah Surip. "Molecular Dynamics Simulation of Ligands from Anredera cordifolia (Binahong) to the Main Protease (Mpro) of SARS-CoV-2." Journal of Tropical Medicine 2022 (November 22, 2022): 1–13. http://dx.doi.org/10.1155/2022/1178228.
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COVID-19 in Indonesia is considered to be entering the endemic phase, and the population is expected to live side by side with the SARS-CoV 2 viruses and their variants. In this study, procyanidin, oleic acid, methyl linoleic acid, and vitexin, four compounds from binahong leaves-tropical/subtropical plant, were examined for their interactions with the major protease (Mpro) of the SARS-CoV 2 virus. Molecular dynamics simulation shows that procyanidin and vitexin have the best docking scores of −9.132 and −8.433, respectively. Molecular dynamics simulation also shows that procyanidin and vitexin have the best Root Mean Square Displacement (RMSD) and Root Mean Square Fluctuation (RMSF) performance due to dominant hydrogen, hydrophobic, and water bridge interactions. However, further strain energy calculation obtained from ligand torsion analyses, procyanidin and vitexin do not conform as much as quercetin as ligand control even though these two ligands have good performance in terms of interaction with the target protein.
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Renadi, Sedin, Anindita Tri Kusuma Pratita, Richa Mardianingrum, and Ruswanto Ruswanto. "The Potency of Alkaloid Derivates as Anti-Breast Cancer Candidates: In Silico Study." Jurnal Kimia Valensi 9, no. 1 (May 31, 2023): 89–108. http://dx.doi.org/10.15408/jkv.v9i1.31481.
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Breast cancer is the most frequent malignancy in women worldwide. One of the target receptors for the treatment of breast cancer are estrogen, progesterone, and HER2 receptors. An alternative treatment using natural ingredients has been developed, one of which is alkaloid compounds. This study aims to determine the activity of alkaloid compounds as anti-breast cancer agents through an in-silico method. Virtual screening (AutoDock Vina), molecular docking (AutoDock Tools), molecular dynamics (Desmond), scanning Lipinski's rule of five, as well as pharmacokinetic and toxicity parameters, were performed. The results of virtual screening, molecular docking, and molecular dynamics show that the compounds daurisoline, solasodine, and sambutoxin have stable interactions with the HER2 receptor, with the lowest values of RMSD (Root Mean Square Deviation) and RMSF (Root Mean Square Fluctuation) compared to other compounds. Based on the results of the study conducted, it was shown that daurisoline, solasodine, and sambutoxin were predicted to be used as anti-HER2 candidates for the treatment of breast cancer.
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Liu, Keyang, Hongyang Li, Xinliang Wang, Yanqi Liu, Liwei Song, and Yuxin Leng. "Timing Fluctuation Correction of A Femtosecond Regenerative Amplifier." Crystals 11, no. 10 (October 14, 2021): 1242. http://dx.doi.org/10.3390/cryst11101242.
Full textAbstract:
We report on the long-term correction of a timing fluctuation between the femtosecond regenerative amplifier and the reference oscillator for the seed 100 PW laser system in the Station of Extreme Light (SEL). The timing fluctuation was characterized by a noncollinear balanced optical cross-correlator that maps the time difference to the sum frequency intensity of the amplifier and oscillator laser pulses. A feedback loop was employed to correct the timing jitter by adjusting the time delay line in the amplifier beam path. The timing fluctuation was reduced to 1.26 fs root-mean-square from hundreds of fs over 10 hours. Benefitting from excellent performance and long-term stability, this timing jitter correction scheme, as a component of optical synchronization in the 100 PW laser facility, will be integrated into SEL.
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Ogami, Y., K. Nishiwaki, and Y. Yoshihara. "ANALYSIS OF ENERGY SPECTRA BY THE VORTEX METHOD WITH ARTIFICIAL TURBULENCE." Revista de Engenharia Térmica 3, no. 2 (December 31, 2004): 143. http://dx.doi.org/10.5380/reterm.v3i2.3528.
Full textAbstract:
First, in order to use as an inlet condition for turbulent simulation, a method is presented
which produces numerically an artificial turbulence, namely, a series of velocity fluctuations
of which frequency is Gaussian, and energy spectrum and root mean square correspond to
the given ones. Besides, the fluctuation data are determined by the characteristic parameters
of turbulent flows such as the inlet mean velocity, the kinematic viscosity, the Kolmogorov
scale and the integral time scale. Our examples show excellent accuracy and flexibility of
the method. Secondly, the vortex method has been studied to see the ability of the method
to deal with turbulent flows. It is found that the energy spectra produced by this agree well
with the ones given as the inlet condition, and that the vortex method is able to produce
turbulent flows with the given parameters described above.
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Takahashi, F., M. D. Vangsness, M. D. Durbin, and W. J. Schmoll. "Structure of Turbulent Hydrogen Jet Diffusion Flames With or Without Swirl." Journal of Heat Transfer 118, no. 4 (November 1, 1996): 877–84. http://dx.doi.org/10.1115/1.2822583.
Full textAbstract:
The near-field turbulent structure of double-concentric hydrogen-air jet diffusion flames, with or without swirl, has been investigated using conditionally sampled, three-component laser-Doppler velocimetry and coherent anti-Stokes Raman spectroscopy. The turbulent flame zone became thinner and shifted inward as the mean jet velocity was increased, whereas swirl created a radial velocity even at the jet-exit plane, thereby broadening and shifting the flame zone outward. The probability-density functions of velocity components, their 21 moments (up to fourth order), mean temperature, and root-mean-square temperature fluctuation were determined in the near field. The data can be used to validate advanced turbulent combustion models.
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Arianie, Lucy, Feri Eko Hermanto, Elvina Dhiaul Iftitah, Warsito Warsito, and Nashi Widodo. "Novel Antimalarial Drug Screening Based on Methyl Eugenol, Cinnamaldehyde, and Thiosemicarbazone with Cysteine Protease Inhibition: In Silico Molecular Docking, Molecular Dynamics, and ADMET Studies." Journal of Pure and Applied Chemistry Research 11, no. 2 (August 31, 2022): 102–12. http://dx.doi.org/10.21776/ub.jpacr.2022.011.02.652.
Full textAbstract:
Plasmodium falciparum malaria contributes to significant global diseases. Computer-aided drug design, screening, and discovery were used to analyze a novel series of Methyl Eugenol Benzaldehyde Thiosemicarbazone (MEBThi) and Methyl Eugenol Cinnamaldehyde Thiosemicarbazone (MECThi) derivatives for malaria falciparum inhibition. This present study showed that 16 molecules from 28 of MEBThi and MECThi have affinities and interaction with active-site residues of cysteine protease, a key player in erythrocyte proliferation of P. falciparum. 13-MECThi demonstrates the best binding affinity at ˗8.0 kcal/mol while co-drug ˗5.6 kcal/mol. Physicochemical and pharmacokinetic assays of 13- MECThi have also revealed this potent compound. Toxicity analysis shows that 13-MECThi does not have mutagenicity and carcinogenicity characters, whereas co-drug has mutagenicity probability. The molecular dynamic evaluation illustrated that the 13-MECThi complex has higher Root Mean Square Deviation (RMSD) values, indicating its structure was more flexible than the chloroquine complex. Root Mean Square Fluctuation (RMSF) complex of receptor and 13-MECThi has no fundamental differences with chloroquine complex. This designed compound should be considered a falciparum antimalarial drug.
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Zhang, Yi, Ting-jian Zhang, Shun Tu, Zhen-hao Zhang, and Fan-hao Meng. "Identification of Novel Src Inhibitors: Pharmacophore-Based Virtual Screening, Molecular Docking and Molecular Dynamics Simulations." Molecules 25, no. 18 (September 8, 2020): 4094. http://dx.doi.org/10.3390/molecules25184094.
Full textAbstract:
Src plays a crucial role in many signaling pathways and contributes to a variety of cancers. Therefore, Src has long been considered an attractive drug target in oncology. However, the development of Src inhibitors with selectivity and novelty has been challenging. In the present study, pharmacophore-based virtual screening and molecular docking were carried out to identify potential Src inhibitors. A total of 891 molecules were obtained after pharmacophore-based virtual screening, and 10 molecules with high docking scores and strong interactions were selected as potential active molecules for further study. Absorption, distribution, metabolism, elimination and toxicity (ADMET) property evaluation was used to ascertain the drug-like properties of the obtained molecules. The proposed inhibitor–protein complexes were further subjected to molecular dynamics (MD) simulations involving root-mean-square deviation and root-mean-square fluctuation to explore the binding mode stability inside active pockets. Finally, two molecules (ZINC3214460 and ZINC1380384) were obtained as potential lead compounds against Src kinase. All these analyses provide a reference for the further development of novel Src inhibitors.
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SHITYAKOV, SERGEY, and THOMAS DANDEKAR. "MOLECULAR DYNAMICS SIMULATION OF POPC AND POPE LIPID MEMBRANE BILAYERS ENFORCED BY AN INTERCALATED SINGLE-WALL CARBON NANOTUBE." Nano 06, no. 01 (February 2011): 19–29. http://dx.doi.org/10.1142/s1793292011002317.
Full textAbstract:
Using classical all-atom molecular dynamics simulation, we investigated the molecular dynamics of palmitoyloleoylphosphatidylcholine and palmitoyloleoylphosphatidylethanolamine membrane bilayers enforced by a single-wall carbon nanotube. We postulated that an insertion of a single-wall carbon nanotube in the center of lipid membrane "strengthens" ambient lipids and prevents the whole system from further destabilization by high temperatures. We implemented root mean square deviation and root mean square fluctuation analyses of simulated structures from their initial states in order to emphasize the molecular dynamics behavior of these structures during 1000 ps simulation time at different temperatures. The data suggest that an intercalated carbon nanotube restrains the conformational freedom of adjacent lipids and hence has an impact on the membrane stabilization dynamics. On the other hand, different lipid membranes may have dissimilarities due to the differing abilities to create a bridge formation between the adherent lipid molecules. The results derived from this work may be of importance in developing stable nanosystems for construction of novel biomaterials and delivery of various biomolecules in the fields of biosensors, biomaterials, and biophysics.
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Wang, Bowen, Xiang Peng, Haidong Wang, Yang Liu, and Hong Guo. "Laser-frequency stabilization with differential single-beam saturated absorption spectroscopy of 4He atoms." Review of Scientific Instruments 93, no. 4 (April 1, 2022): 043001. http://dx.doi.org/10.1063/5.0084605.
Full textAbstract:
Differential single-beam saturated-absorption spectroscopy (DSSAS) is proposed to stabilize lasing frequency and suppress Doppler-broadened background and common-mode optical noise. The spectral first-derivative demodulated signal of metastable [Formula: see text] atoms is used as an error signal to stabilize a fiber laser around 1083 nm. Experimental results show that, compared with existing non-DSSAS frequency stabilization, DSSAS stabilization produces better stability and lower fluctuations, especially for frequency-noise-corrupted lasers. In DSSAS stabilization, for data acquired over 7000 s, the root mean square frequency fluctuation of the fiber laser is 16.4 kHz, and the frequency stability described by the modified Allan deviation is 4.1 × 10−12 at 100 s. Even for a defective laser with poor frequency stability, the proposed scheme demonstrates experimentally high capability of noise suppression and reduces the frequency fluctuations by two orders of magnitude. Given its simplicity and compact design, frequency stabilization by DSSAS is promising for quantum-sensor applications, such as atomic magnetometers, atomic gyroscopes, and atomic clocks.
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Alomair, Lamya, Sabeena Mustafa, Mohsin Saleet Jafri, Wardah Alharbi, Abdulrhman Aljouie, Fahad Almsned, Mohammed Alawad, Yahya Abdulfattah Bokhari, and Mamoon Rashid. "Molecular Dynamics Simulations to Decipher the Role of Phosphorylation of SARS-CoV-2 Nonstructural Proteins (nsps) in Viral Replication." Viruses 14, no. 11 (November 2, 2022): 2436. http://dx.doi.org/10.3390/v14112436.
Full textAbstract:
Protein phosphorylation is a post-translational modification that enables various cellular activities and plays essential roles in protein interactions. Phosphorylation is an important process for the replication of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To shed more light on the effects of phosphorylation, we used an ensemble of neural networks to predict potential kinases that might phosphorylate SARS-CoV-2 nonstructural proteins (nsps) and molecular dynamics (MD) simulations to investigate the effects of phosphorylation on nsps structure, which could be a potential inhibitory target to attenuate viral replication. Eight target candidate sites were found as top-ranked phosphorylation sites of SARS-CoV-2. During the process of molecular dynamics (MD) simulation, the root-mean-square deviation (RMSD) analysis was used to measure conformational changes in each nsps. Root-mean-square fluctuation (RMSF) was employed to measure the fluctuation in each residue of 36 systems considered, allowing us to evaluate the most flexible regions. These analysis shows that there are significant structural deviations in the residues namely nsp1 THR 72, nsp2 THR 73, nsp3 SER 64, nsp4 SER 81, nsp4 SER 455, nsp5 SER284, nsp6 THR 238, and nsp16 SER 132. The identified list of residues suggests how phosphorylation affects SARS-CoV-2 nsps function and stability. This research also suggests that kinase inhibitors could be a possible component for evaluating drug binding studies, which are crucial in therapeutic discovery research.
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Gao, Tianyun, Heiko Schmidt, Marten Klein, Jianhan Liang, Mingbo Sun, Chongpei Chen, and Qingdi Guan. "One-dimensional turbulence modeling of compressible flows. I. Conservative Eulerian formulation and application to supersonic channel flow." Physics of Fluids 35, no. 3 (March 2023): 035115. http://dx.doi.org/10.1063/5.0125514.
Full textAbstract:
Accurate but economical modeling of supersonic turbulent boundary layers is a standing challenge due to the intricate entanglement of temperature, density, and velocity fluctuations on top of the mean-field variation. Application of the van Driest transformation may describe well the mean state but cannot provide detailed flow information. This lack-in modeling coarse and fine-scale variability is addressed by the present study using a stochastic one-dimensional turbulence (ODT) model. ODT is a simulation methodology that represents the evolution of turbulent flow in a low-dimensional stochastic way. In this study, ODT is extended to fully compressible flows. An Eulerian framework and a conservative form of the governing equations serve as the basis of the compressible ODT model. Computational methods for statistical properties based on ODT realizations are also extended to compressible flows, and a comprehensive way of turbulent kinetic energy budget calculation based on compressible ODT is put forward for the first time. Two canonical direct numerical simulation cases of supersonic isothermal-wall channel flow at Mach numbers 1.5 and 3.0 with bulk Reynolds numbers 3000 and 4880, respectively, are used to validate the extended model. A rigorous numerical validation is presented, including the first-order mean statistics, the second-order root mean square statistics, and higher-order turbulent fluctuation statistics. In ODT results, both mean and root mean square profiles are accurately captured in the near-wall region. Near-wall temperature spectra reveal that temperature fluctuations are amplified at all turbulent scales as the effects of compressibility increase. This phenomenon is caused by intensified viscous heating at a higher Mach number, which is indicated by the steeper profiles of viscous turbulent kinetic energy budget terms in the very near-wall region. The low computational cost and predictive capabilities of ODT suggest that it is a promising approach for detailed modeling of highly turbulent compressible boundary layers. Furthermore, it is found that the ODT model requires a Mach-number-dependent increase in a viscous penalty parameter Z in wall-bounded turbulent flows to enable accurate capture of the buffer layer.
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Ignatchenko, V. A., and D. S. Polukhin. "Spin and Elastic Waves with the Random Coupling Parameter." Solid State Phenomena 190 (June 2012): 51–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.51.
Full textAbstract:
Dynamic susceptibilities (Greens function) in a system of two wave fields of different physical nature connected by the zero-mean random coupling parameter are studied. Magnetoelastic waves in zero-mean magnetostrictive media are considered. It is shown that the Greens functions of the spin and elastic waves at the intersection of the initial dispersion laws have the form of broad single-mode peaks with the fine structure on the tops of these peaks: the narrow resonance on the top of and the narrow antiresonance on the top of . For the long-wave inhomogeneities the widths of the broad peaks and narrow peaks are determined by the root-mean-square fluctuation and the correlation wave number, respectively.
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Shao, Dongqing, Qun Zhang, Peng Xu, and Zhouting Jiang. "Effects of the Temperature and Salt Concentration on the Structural Characteristics of the Protein (PDB Code 1BBL)." Polymers 14, no. 11 (May 24, 2022): 2134. http://dx.doi.org/10.3390/polym14112134.
Full textAbstract:
The effect of the temperature and salt solution on the structural characteristics of the protein 1BBL was investigated by molecular dynamics simulations. The paper presents simulation results regarding the non-bonded energy and the structural stability of the protein immersed in salt solutions with different concentrations and temperatures. Our work demonstrates that the electrostatic potential energy and van der Waals energy of the system show the opposite changes with the influence of the external environment. Since the electrostatic potential energy changes more obviously, it is dominated in the non-bonding interactions. The structural parameters, such as the root mean square deviation and the radius of gyration, increased initially and decreased afterward with the increase of the salt concentration. The protein presented the loose structure with a relative low stability when it was immersed in a monovalent solution with a salt concentration of 0.8 mol/L. The salt concentration corresponding to the maximum value of structural parameters in the monovalent salt solution was double that in the divalent salt solution. It was also concluded that the protein presented a compact and stable structure when immersed in salt solutions with a high concentration of 2.3 mol/L. The analysis of the root mean square deviation and root mean square fluctuation of the protein sample also exhibited that the structural stability and chain flexibility are strongly guided by the effect of the temperature. These conclusions help us to understand the structural characteristics of the protein immersed in the salt solutions with different concentrations and temperatures.
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Huang, Wantao, Yang Li, Peng Zhang, Lujun Fang, and Dong Hou. "Femtosecond-Level Frequency Transfer at 10 GHz over Long Fiber Link with Optical–Electronic Joint Compensation." Applied Sciences 12, no. 21 (November 7, 2022): 11262. http://dx.doi.org/10.3390/app122111262.
Full textAbstract:
We report a fiber-optic 10 GHz frequency transfer technique based on an optical–electronic joint phase compensator. A highly stable frequency signal at 10 GHz was transferred in a 50-km long fiber link by using this technique. Two key parameters of the frequency dissemination, the timing fluctuation and frequency stability were both measured. The experimental results show the root-mean-square timing fluctuation of the transferred microwave is about 103 fs within 10,000 s, and the frequency stability for the transmission link is 2.2 × 10−14 at 1 s and 8.5 × 10−17 at 2000 s. The technique proposed in this paper provides a powerful tool which can be used to transfer atomic clocks (e.g., commercial H-master and Cs clocks) in a long fiber link.
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Saida, Tsuyoshi, Masayuki Kawada, Daijiro Kuroki, Yuki Nakai, Takasuke Miyazaki, Ryoji Kiyama, and Yasuhiro Tsuneyoshi. "Accelerometer Measurement of Trunk Lateral Fluctuation During Walking Following Total Knee Arthroplasty in Patients With Osteoarthritis." Journal of Aging and Physical Activity 28, no. 5 (October 1, 2020): 669–74. http://dx.doi.org/10.1123/japa.2019-0149.
Full textAbstract:
This study aimed to clarify the effect of total knee arthroplasty (TKA) on trunk fluctuation and regularity of gait in patients with knee osteoarthritis by an accelerometer. The participants included 18 patients with knee osteoarthritis undergoing TKA. The gait at a comfortable velocity was assessed pre- and post-TKA by a triaxial accelerometer attached to the neck and lumbar regions. Measurement post-TKA was performed 4 weeks after surgery. Trunk fluctuation was estimated by the root mean square (RMS) of acceleration and RMS ratio (the ratio of RMS in each direction to the total RMS). Regularity of gait was estimated using the autocorrelation function. The results showed that TKA significantly decreased the RMS ratio in mediolateral acceleration of the neck and lumbar regions and reduced gait regularity. TKA appears to reduce compensatory trunk motion through the improvement of knee function. An assessment of trunk fluctuation using an accelerometer is useful for the clinical assessment of patients with knee osteoarthritis pre- and post-TKA.
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Turner, Samuel G. D., and Christopher S. Reynolds. "Investigating the theory of propagating fluctuations with numerical models of stochastic accretion discs." Monthly Notices of the Royal Astronomical Society 504, no. 1 (March 26, 2021): 469–86. http://dx.doi.org/10.1093/mnras/stab875.
Full textAbstract:
ABSTRACT Across a large range of scales, accreting sources show remarkably similar patterns of variability, most notably the log-normality of the luminosity distribution and the linear root-mean square (rms)–flux relationship. These results are often explained using the theory of propagating fluctuations in which fluctuations in the viscosity create perturbations in the accretion rate at all radii, propagate inwards, and combine multiplicatively. While this idea has been extensively studied analytically in a linear regime, there has been relatively little numerical work investigating the non-linear behaviour. In this paper, we present a suite of stochastically driven 1D α-disc simulations, exploring the behaviour of these discs. We find that the eponymous propagating fluctuations are present in all simulations across a wide range of model parameters, in contradiction to previous work. Of the model parameters, we find by far the most important to be the time-scale on which the viscosity fluctuations occur. Physically, this time-scale will depend on the underlying physical mechanism, thought to be the magnetorotational instability (MRI). We find a close relationship between this fluctuation time-scale and the break frequency in the power spectral density of the luminosity, a fact which could allow observational probes of the behaviour of the MRI dynamo. We report a fitting formula for the break frequency as a function of the fluctuation time-scale, the disc thickness, and the mass of the central object.
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Duncan, James H., and Athanassios A. Dimas. "Surface ripples due to steady breaking waves." Journal of Fluid Mechanics 329 (December 25, 1996): 309–39. http://dx.doi.org/10.1017/s0022112096008932.
Full textAbstract:
Breaking waves generated by a two-dimensional hydrofoil moving near a free surface at constant speed (U∞), angle of attack and depth of submergence were studied experimentally. The measurements included the mean and fluctuating shape of the breaking wave, the surface ripples downstream of the breaker and the vertical distribution of vertical and horizontal velocity fluctuations at a single station behind the breaking waves. The spectrum of the ripples is highly peaked and shows little variation in both its peak frequency and its shape over the first three wavelengths of the wavetrain following the breaker. For a given speed, as the breaker strength is increased, the high-frequency ends of the spectra are nearly identical but the spectral peaks move to lower frequencies. A numerical instability model, in conjunction with the experimental data, shows that the ripples are generated by the shear flow developed at the breaking region. The spectrum of the vertical velocity fluctuations was also found to be highly peaked with the same peak frequency as the ripples, while the corresponding spectrum of the horizontal velocity fluctuations was found not to be highly peaked. The root-mean-square (r.m.s.) amplitude of the ripples (νrms) increases with increasing speed and with decreasing depth of submergence of the hydrofoil, and decreases as x-1/2 with increasing distance x behind the breaker. The quantity (gνrms)/(U∞Vrms) (where Vrms is the maximum r.m.s. vertical velocity fluctuation and g is the gravitational acceleration) was found to be nearly constant for all of the measurements.
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Endou, Akira, Setsunari Inoue, Keiichi Setoguchi, Kimihide Miyaguchi, and Junichi Endo. "Calibration method of electromagnetic-flowmeter for LMFBR using root mean square frequency weighted by power spectral density of output voltage fluctuation." Progress in Nuclear Energy 15 (January 1985): 719–26. http://dx.doi.org/10.1016/0149-1970(85)90101-5.
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Wei, Wang Ru. "Experimental Study on Hydraulic Characteristics of X-Shape Flaring Gate Pier and Deflecting Stilling Basin United Energy Dissipator." Applied Mechanics and Materials 376 (August 2013): 279–83. http://dx.doi.org/10.4028/www.scientific.net/amm.376.279.
Full textAbstract:
In this paper, the hydraulic characteristics of X-shape flaring gate pier and deflecting stilling basin united energy dissipater are analyzed experimentally on a physical model for large discharge, such as time average impact pressure, close-to-bed velocity in stilling basin and pressure fluctuations. The results show that for large discharge, the deflecting region is the main impact region and the max impact pressure decays with increased water discharge. The close-to-bed velocity decays fast in deflecting stilling basin along the flow direction and for discharge of 14143 m3/s and 17743 m3/s, the max root-mean-square of pressure fluctuation are 2.48 and 2.39 respectively. So the X-shape flaring gate pier and deflecting stilling basin united energy dissipater is a relatively good flood discharge structures combination, which provides strong references for the design of energy dissipater in hydraulic engineering.
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Shafique, Qurrat ul Ain, Hafiz Muzzammel Rehman, Tahreem Zaheer, Rana Adnan Tahir, Munir Ahmad Bhinder, Roquyya Gul, and Mahjabeen Saleem. "A Computational Approach to Modeling an Antagonistic Angiogenic VEGFR1-IL2 Fusion Protein for Cancer Therapy." Bioinformatics and Biology Insights 15 (January 2021): 117793222110432. http://dx.doi.org/10.1177/11779322211043297.
Full textAbstract:
In cancer treatment, immunotherapy has great potential for improving the prognosis of patients with hematologic and solid malignancies. In this study, various bioinformatics tools and servers were used to design an antiangiogenic fusion protein. After comprehensive evaluation, an antiangiogenic fusion protein was designed using a soluble extracellular domain of human vascular endothelial growth factor receptor 1 (sVEGFR-1) and human interleukin-2 (IL-2) joined by a flexible linker. The final construct was composed of 875 amino acids. The secondary structure of the fusion protein, obtained by CFSSP, PSIPRED, and SOPMA tools, consisted of 14.17% helices, 29.71% extended strands, 4.69% beta turns and 51.43% random coils. Tertiary structure prediction by Raptor X showed that the fusion protein comprises 3 domains with 875 modeled amino acids, out of which 26 positions (2%) were considered disordered. The Ramachandran plot revealed 89.3%, 7.1%, and 3.6% amino acid residues in favored, allowed, and outlier regions, respectively. Physical features of the Molecular Dynamic (MD) simulated system such as root mean square deviation, root mean square fluctuation, solvent-on hand surface region, and radius of gyration identified the fusion construct as a stable and compact protein with few fluctuations in its overall structure. Docking of the fusion protein showed that interaction between sVEGFR-1/VEGFA and IL-2/IL-2R still exists. In silico analysis revealed that the fusion protein comprising IL-2 and sVEGFR-1 has stable structure and the selected linker can efficiently separate the two domains. These observations may be helpful in determining protein stability prior to protein expression.
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Arba, Muhammad, Malindo Sufriadin, and Daryono Hadi Tjahjono. "Identification of Phosphatidylinositol 3-kinase δ (PI3Kδ) Inhibitor: Pharmacophore-based Virtual Screening and Molecular Dynamics Simulation." Indonesian Journal of Chemistry 20, no. 5 (July 18, 2020): 1070. http://dx.doi.org/10.22146/ijc.47327.
Full textAbstract:
Phosphatidylinositol 3-kinase δ (PI3Kδ) is a validated drug target for the treatment of cancer. The present study aims to search for new inhibitors of PI3Kδ by employing pharmacophore modelling using LigandScout Advanced 4.3 software. The three hydrogen bond acceptors and two hydrophobic features were proposed as a pharmacophore model using LASW1976 structure. The model was then validated using the Area Under Curve (AUC) of Receiver Operating Characteristic (ROC) and GH score. It was used to screen new molecules in the ZINC database, which resulted in 599 hits. All 599 hits were then docked into PI3Kδ protein, and five best hits were submitted to 50 ns molecular dynamics simulations. Each hit complexed with PI3Kδ underwent minor conformational changes as indicated by the values of Root Mean Square Deviation (RMSD) and Root Mean Square Fluctuation (RMSF). Furthermore, prediction of the binding free energy using Molecular Mechanics-Poisson Boltzmann Surface Area (MM-PBSA) method showed that five hits, i.e., Lig25/ZINC253496376, Lig682/ZINC98047241, Lig449/ZINC85878047, Lig554/ZINC253389510, and Lig199/ZINC12638303, had lower binding energy compared to LASW1976. This result indicated their potentials as new inhibitors of PI3Kδ.
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Lopus, Merlin, D. Meshach Paul, and R. Rajasekaran. "Unraveling the Deleterious Effects of Cancer-Driven STK11 Mutants through Conformational Sampling Approach." Cancer Informatics 15 (January 2016): CIN.S38044. http://dx.doi.org/10.4137/cin.s38044.
Full textAbstract:
Tumor suppressor gene, STK11, encodes for serine-threonine kinase, which has a critical role in regulating cell growth and apoptosis. Mutations of the same lead to the inactivation of STK11, which eventually causes different types of cancer. In this study, we focused on identifying those driver mutations through analyzing structural variations of mutants, viz., D194N, E199K, L160P, and Y49D. Native and the mutants were analyzed to determine their geometrical deviations such as root-mean-square deviation, root-mean-square fluctuation, radius of gyration, potential energy, and solvent-accessible surface area using conformational sampling technique. Additionally, the global minimized structure of native and mutants was further analyzed to compute their intramolecular interactions and distribution of secondary structure. Subsequently, simulated thermal denaturation and docking studies were performed to determine their structural variations, which in turn alter the formation of active complex that comprises STK11, STRAD, and MO25. The deleterious effect of the mutants would result in a comparative loss of enzyme function due to variations in their binding energy pertaining to spatial conformation and flexibility. Hence, the structural variations in binding energy exhibited by the mutants, viz., D194N, E199K, L160P, and Y49D, to that of the native, consequently lead to pathogenesis.
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Li, Yang, Lijing Zhang, Yuan Tian, and Wanqiang Qi. "Research on Teaching Practice of Blended Higher Education Based on Deep Learning Route." Computational Intelligence and Neuroscience 2022 (January 13, 2022): 1–8. http://dx.doi.org/10.1155/2022/5906335.
Full textAbstract:
This paper establishes a hybrid education teaching practice quality evaluation system in colleges and constructs a hybrid teaching quality evaluation model based on a deep belief network. Karl Pearson correlation coefficient and root mean square error (RMSE) indicators are used to measure the closeness and fluctuation between the effective online teaching quality evaluation results evaluated by this method and the actual teaching quality results. The experimental results show the following: (1) As the number of iterations increases, the fitting error of the DBN model decreases significantly. When the number of iterations reaches 20, the fitting error of the DBN model stabilizes and decreases to below 0.01. The experimental results show that the model used in this method has good learning and training performance, and the fitting error is low. (2) The evaluation correlation coefficients are all greater than 0.85, and the root mean square error of the evaluation is less than 0.45, indicating that the evaluation results of this method are similar to the actual evaluation level and have small errors, which can be effectively applied to online teaching quality evaluation in colleges and universities.
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Tallei, Trina Ekawati, Fatimawali, Ahmad Akroman Adam, Mona M. Elseehy, Ahmed M. El-Shehawi, Eman A. Mahmoud, Adinda Dwi Tania, et al. "Fruit Bromelain-Derived Peptide Potentially Restrains the Attachment of SARS-CoV-2 Variants to hACE2: A Pharmacoinformatics Approach." Molecules 27, no. 1 (January 1, 2022): 260. http://dx.doi.org/10.3390/molecules27010260.
Full textAbstract:
Before entering the cell, the SARS-CoV-2 spike glycoprotein receptor-binding domain (RBD) binds to the human angiotensin-converting enzyme 2 (hACE2) receptor. Hence, this RBD is a critical target for the development of antiviral agents. Recent studies have discovered that SARS-CoV-2 variants with mutations in the RBD have spread globally. The purpose of this in silico study was to determine the potential of a fruit bromelain-derived peptide. DYGAVNEVK. to inhibit the entry of various SARS-CoV-2 variants into human cells by targeting the hACE binding site within the RBD. Molecular docking analysis revealed that DYGAVNEVK interacts with several critical RBD binding residues responsible for the adhesion of the RBD to hACE2. Moreover, 100 ns MD simulations revealed stable interactions between DYGAVNEVK and RBD variants derived from the trajectory of root-mean-square deviation (RMSD), radius of gyration (Rg), and root-mean-square fluctuation (RMSF) analysis, as well as free binding energy calculations. Overall, our computational results indicate that DYGAVNEVK warrants further investigation as a candidate for preventing SARS-CoV-2 due to its interaction with the RBD of SARS-CoV-2 variants.
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Huang, Xiaoqiao, Chao Zhang, Qiong Li, Yonghang Tai, Bixuan Gao, and Junsheng Shi. "A Comparison of Hour-Ahead Solar Irradiance Forecasting Models Based on LSTM Network." Mathematical Problems in Engineering 2020 (August 26, 2020): 1–15. http://dx.doi.org/10.1155/2020/4251517.
Full textAbstract:
The intermittence and fluctuation character of solar irradiance places severe limitations on most of its applications. The precise forecast of solar irradiance is the critical factor in predicting the output power of a photovoltaic power generation system. In the present study, Model I-A and Model II-B based on traditional long short-term memory (LSTM) are discussed, and the effects of different parameters are investigated; meanwhile, Model II-AC, Model II-AD, Model II-BC, and Model II-BD based on a novel LSTM-MLP structure with two-branch input are proposed for hour-ahead solar irradiance prediction. Different lagging time parameters and different main input and auxiliary input parameters have been discussed and analyzed. The proposed method is verified on real data over 5 years. The experimental results demonstrate that Model II-BD shows the best performance because it considers the weather information of the next moment, the root mean square error (RMSE) is 62.1618 W/m2, the normalized root mean square error (nRMSE) is 32.2702%, and the forecast skill (FS) is 0.4477. The proposed algorithm is 19.19% more accurate than the backpropagation neural network (BPNN) in terms of RMSE.
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Shreekumar, R. Kumar, and K. S. Gandhi. "Breakage of a drop of inviscid fluid due to a pressure fluctuation at its surface." Journal of Fluid Mechanics 328 (December 10, 1996): 1–17. http://dx.doi.org/10.1017/s0022112096008622.
Full textAbstract:
In this work, an attempt is made to gain a better understanding of the breakage of low-viscosity drops in turbulent flows by determining the dynamics of deformation of an inviscid drop in response to a pressure variation acting on the drop surface. Known scaling relationships between wavenumbers and frequencies, and between pressure fluctuations and velocity fluctuations in the inertial subrange are used in characterizing the pressure fluctuation. The existence of a maximum stable drop diameter dmax follows once scaling laws of turbulent flow are used to correlate the magnitude of the disruptive forces with the duration for which they act.Two undetermined dimensionless quantities, both of order unity, appear in the equations of continuity, motion, and the boundary conditions in terms of pressure fluctuations applied on the surface. One is a constant of proportionality relating root-mean-square values of pressure and velocity differences between two points separated by a distance l. The other is a Weber number based on turbulent stresses acting on the drop and the resisting stresses in the drop due to interfacial tension. The former is set equal to 1, and the latter is determined by studying the interaction of a drop of diameter equal to dmax with a pressure fluctuation of length scale equal to the drop diameter. The model is then used to study the breakage of drops of diameter greater than dmax and those with densities different from that of the suspending fluid.It is found that, at least during breakage of a drop of diameter greater than dmax by interaction with a fluctuation of equal length scale, a satellite drop is always formed between two larger drops. When very large drops are broken by smaller-length-scale fluctuations, highly deformed shapes are produced suggesting the possibility of further fragmentation due to instabilities. The model predicts that as the dispersed-phase density increases, dmax decreases.