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Statistical Analysis of the Surface Roughness on Aircraft Icing

JOURNAL OF AIRCRAFT 2024年第1期61卷 245-256页

作者： Sotomayor-Zakharov, Denis Radenac, Emmanuel Gallia, Mariachiara Guardone, Alberto Knop, Inken Tech Univ Carolo Wilhelmina Braunschweig Inst Fluid Mech Hermann Blenk Str 37 D-38106 Braunschweig Germany Univ Toulouse ONERA DMPE 2 Ave Edouard Belin F-31055 Toulouse France Polytech Univ Milan Dept Aerosp Sci & Technol Via Masa 34 I-20156 Milan Italy Tech Univ Carolo Wilhelmina Braunschweig Inst Fluid Mech Multiphase Flows & Icing Workgrp Hermann Blenk Str 37 D-38106 Braunschweig Germany

A statistical analysis of the surface roughness is performed on experimentally obtained ice shapes on an asymmetrical airfoil at Rec approximate to 2 & sdot;106. The ice shapes were generated in the Icing Wind Tunnel of the Technical University of Braunschweig under Appendix C and O conditions of the EASA airplane certification standards as part of the ICE GENESIS project. The photogrammetry method is used for the digitization of the experimental ice shapes, while statistical parameters such as the mean ice shape and the local root mean square (RMS) of the ice geometry are extracted using a traditional surface projection method, as well as a self-organizing maps approach. Results show the evolution of the statistical parameters over time and the influence of the freestream static temperature on these parameters. A comparison between the experimental values of the local RMS of the ice geometry and a correlation for roughness prediction is presented, showing a good match with the original formulation of the correlation for cases under Appendix C conditions while having a good match with Appendix O conditions when a temperature correction factor is applied to the formulation. Additionally, results show an almost linear growth of roughness over the whole accretion time.

关键词： probability density functions Surface Properties Freestream Velocity Surface Roughness Distributed Roughness Aircraft Icing Icing Wind Tunnel Photogrammetry Supercooled Large Droplets Asymmetric Airfoil

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Effects of Liquid Film Instability on Spray Features of Liquid-Liquid Pintle Injectors

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AIAA JOURNAL 2024年第11期62卷 4247-4264页

作者： Zhao, Fan Zhang, Haibin Zhao, Liang Bai, Bofeng Xi An Jiao Tong Univ Xian 710049 Peoples R China State Key Lab Multiphase Flow Power Engn Xian Peoples R China Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn Xian Peoples R China

As one of the crucial structural parameters for the pintle injectors, the design of the skip distance ratio is still heavily empirical-dependent in engineering, and the intrinsic correlations between the skip distance ratio and spray characteristics of liquid-liquid pintle injectors are also unclear. Inspired by the observations that the instability of axial liquid film exerts significant influence on the downstream spray behaviors of a liquid-liquid pintle injector, the influence of the skip distance ratio on the instability of the axial liquid film and the subsequent spray characteristics of the pintle injector was experimentally investigated. The spray steadiness of the pintle injector was evaluated based on the instantaneous images using the proper orthogonal decomposition technique, and the effects of the skip distance ratio and the momentum ratio on the spray features were analyzed. Furthermore, a proactive strategy was proposed to adjust the liquid film instability by modifying the outer wall morphology of the pintle post, and the verification experiments were carried out based on three different wall morphologies. It was discovered that the rough wall enhances the axial liquid film instability and promotes the liquid sheet breakup and atomization of the pintle injector. These results provide new insights and valuable references for the optimization design of pintle injectors.

关键词： Pintle Injector Bipropellants probability density functions Spray Visualization Image Analysis Doublet Impinging Injectors Twin-Fluid Atomization Kelvin-Helmholtz Instability Boundary Layer Instability

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Fractal-fractional estimations of Bullen-type inequalities with applications

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AIN SHAMS ENGINEERING JOURNAL 2024年第12期15卷

作者： Butt, Saad Ihsan Yasin, Muhammad Umar Tipuric-Spuzevic, Sanja Bin-Mohsin, Bandar COMSATS Univ Islamabad Dept Math Lahore Campus Lahore Pakistan Univ Split Fac Chem & Technol Rudera Boskovica 35 Split 21000 Croatia King Saud Univ Coll Sci Math Dept POB 2455 Riyadh 11451 Saudi Arabia

The study of inequalities inside fractal domains has been stimulated by the growing interest in fractional calculus for the applied and mathematical sciences. This work uses extended fractional integrals in fractal domains to prove new Bullen-type inequalities for differentiable convex functions. By showing how these operators and inequalities can convert classical inequalities into fractal sets, it fills a vacuum in the literature on fractal-fractional integral inequalities. Using extended fractional integral operators, we derive new fractal-fractional estimates and Bullen-type inequalities, accompanied by thorough mathematical derivations and graphical validations. We show optimal results derived from new Bullen-type inequalities for fractal domains. We confirm our results with mathematical examples and graphs, improving models for complicated problems in fractal contexts. In particular, our findings have important ramifications for special means on fractal sets, probability density functions, and quadrature formulas, as well as for future study and applications.

关键词： Extended fractal-fractional integral operators probability density functions Bullen inequalities Convex function Optimise bounds Quadrature formulas

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Reliability of Hypersonic Airfoil with Freeplay and Stochasticity via Nonlinear Energy Sink

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AIAA JOURNAL 2024年第9期62卷 3258-3270页

作者： Guo, Weili Xu, Yong Liu, Qi Lenci, Stefano Li, Guangning Northwestern Polytech Univ Sch Math & Stat Xian 710072 Peoples R China MOE Key Lab Complex Sci Aerosp Xian 710072 Peoples R China Tokyo Inst Technol Dept Syst & Control Engn Tokyo 1528552 Japan Polytech Univ Marche Dept Civil & Bldg Engn & Architecture I-60131 Ancona Italy Northwestern Polytech Univ Sch Astronaut Xian 710072 Peoples R China

The reliability of a pitch-plunge hypersonic airfoil in random fluctuating flow with both cubic and freeplay nonlinearity is examined. The Hopf bifurcation and dynamic responses of the hypersonic airfoil are performed. To analyze the reliability, the effects of stochasticity on the dynamic behaviors of the hypersonic airfoil model are discussed in detail. Several unwanted phenomena that result in the failure of the airfoil structure are induced by random fluctuations. Subsequently, the reliability of the airfoil model is defined and analyzed according to the first passage failure criteria. The effects of different parameters on the reliability are investigated. Furthermore, a nonlinear energy sink is introduced to suppress the vibration of the airfoil and enhance the reliability. Two-dimensional reliability regions of the airfoil model are given to provide the safety parameter region. The results show that the reliability of the airfoil model is significantly improved with the nonlinear energy sink. This work will provide new insights into the safety design of hypersonic aircraft.

关键词： Hypersonic Aircraft Mechanical and Structural Vibrations Structural Reliability Analysis Aircraft Wing Design Aerodynamics probability density functions Nonlinear Energy Sink Reliability Design Random Fluctuation Aeroelasticity

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Space Extended Target Tracking Using Poisson Multi-Bernoulli Mixture Filtering with Nonlinear Measurements

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2024年第1期47卷 87-98页

作者： Hua, Bing Yang, Guang Wu, Yunhua Chen, Zhiming Nanjing Univ Aeronaut & Astronaut Coll Astronaut Nanjing 211106 Peoples R China Nanjing Univ Aeronaut & Astronaut Key Lab Space Photoelect Detect & Percept Minist Ind & Informat Technol Nanjing 211106 Peoples R China

The number of space targets in the near-Earth orbit has greatly increased, and space-based radar has the advantage of high resolution and high accuracy tracking to enhance the tracking efficiency of space extended targets (SET). We propose a gamma Gaussian inverse Wishart based on a matched linearization-Poisson multi-Bernoulli mixture (GGIWML-PMBM) filter to estimate the motion state and shape size of the SET. For the random matrix that can only describe the distribution under which the measurements are linear, the measurements of the spatial target are linearized using matched linearization, and the extended information is preserved in the second-order central moments. The transfer density and likelihood function of GGIW are nonlinear for Poisson measurements with nonlinear Gaussian spatial distributions, and the single-target densities and normalizing constants of the PMBM filter are not closed form. The prediction and update of PMBM include Gaussian-weighted integral calculation, for which different nonlinear approximation methods are used to calculate the weighted integral and derive the closed form of GGIWML-PMBM. Finally, the simulation scenarios of low-orbit single-radar sensor tracking near SET and group SET are established, and the results show that the tracking accuracy can reach 2.6 m for near SET and 6.6 m in group SET.

关键词： Space Based Radar Sensors Near Earth Orbit Satellite Constellations Light Detection and Ranging probability density functions Planets Earth Centered Inertial Electromagnetic Interference Space Science and Technology

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Evolution of neuron firing and connectivity in neuronal plasticity with application to Parkinson's disease

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PHYSICA D-NONLINEAR PHENOMENA 2024年 458卷

作者： Mariano, Paolo Maria Spadini, Marco Univ Firenze DICEA via Santa Marta 3 I-50139 Florence Italy Univ Firenze DIMAI via Santa Marta 3 I-50139 Florence Italy

We unify different modeling structures for neuron state evolution showing how they can be derived from an invariance requirement imposed to a dissipation inequality under diffeomorphism-based changes of observer in the physical space. This is a completely non-standard way of using the second law of thermodynamics, although in isothermal setting, a law otherwise commonly used for determining constitutive restrictions and admissibility conditions as those pertaining to shock waves. In this setting, we also consider a time-varying neuronal connectivity and derive the consistent structure of its evolution equation from the same invariance principle. In the case of Parkinson, the connectivity depends also on the distribution of calcium channels that bring dopamine excess. Under special conditions, we show how the connectivity probability distribution changes in time and is influenced by the one of calcium channels. We account for memory effects in the cortical matter, namely dependence on firing and connectivity histories.

关键词： Neuron firing Brain plasticity Parkinson's disease Covariance probability density functions

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Identification of probability distributions of SCFs in three-planar KT-joints

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OCEAN ENGINEERING 2024年第Part3期312卷

作者： Zavvar, Esmaeil Taveira-Pinto, Francisco Rosa-Santos, Paulo Univ Porto FEUP Fac Engn Dept Civil Engn Porto Portugal Univ Porto CIIMAR Interdisciplinary Ctr Marine & Environm Res Porto Portugal

KT-joints are crucial in jacket platforms, providing structural integrity by effectively transferring loads between the main chord and braces. Their robust design ensures stability and durability in harsh offshore environments, preventing structural failures and enhancing the platform's overall safety and performance. This study presents the findings of finite element (FE) analysis conducted on 324 tubular three-planar KT-joints subjected to in-plane bending (IPB) loadings. The purpose of the research was to generate a probability distribution (PD) for the stress concentration factors (SCFs) under bending moments. To the authors' knowledge, no previous research has analyzed the PD of the maximum SCFs in three-planar KT-joints. Consequently, data representing the maximum SCFs were collected from the three-planar KT connections. The maximum likelihood method was used to determine the distribution parameters. The goodness-of-fit of the Generalized Extreme Value distribution was assessed using the Kolmogorov-Smirnov (KS) and Chi-square (CS) tests. The results indicated that this distribution is the most suitable for modeling three-planar KT-joints under IPB loading. In the subsequent stage, well-defined theoretical probability density functions (PDFs) and cumulative distribution functions (CDFs) were developed. Furthermore, probability-probability diagrams demonstrated that the proposed PD closely aligns with the observed data.

关键词： Tubular KT-Connection Chi-squared Three-planar KT-Joints Kolmogorov-Smirnov Cumulative distribution function probability density functions

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Recurrence Times of Large Earthquakes: Assimilating the Effect of Seismic Coupling into a Renewal Model

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BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA 2024年第3期114卷 1754-1761页

作者： Zoller, Gert Univ Potsdam Inst Math Potsdam Germany

A renewal model for estimating recurrence times of large earthquakes is presented, which allows one to assimilate data from paleo, historic, and instrumental earthquake data as well as geodetic information in a simple and efficient way using three parameters: the Richter bvalue, the mean recurrence time mu T of paleo and historic earthquakes, and the seismic coupling coefficient chi. The core of the model is a state variable with linear drift in time reflecting Reid's elastic rebound theory, decorated with random fluctuations modeling small and intermediate earthquakes. Furthermore, it is assumed that a fraction between 0% and 100% of the average seismic moment is released seismically, and the remaining part corresponds to aseismic processes such as creep. The model extends former renewal models of Matthews et al. (2002) and Z & ouml;ller et al. (2008). Results for different regions indicate overall good performance and thus suggest that the model provides physically motivated constraints for recurrence time estimations in contrast to the standard fitting of a few data points to an assumed distribution.

关键词： b-values coupling creep deformation earthquake prediction earthquakes geodesy great earthquakes probability density functions recurrence interval renewal models renewal seismic coupling seismic coupling coefficient seismic moment seismic renewal models seismic sequences statistical analysis temporal distribution time series analysis

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Wavelet-Based Characterization of Spatiospectrotemporal Structures in F404 Engine Jet Noise

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AIAA JOURNAL 2024年第11期62卷 4399-4410页

作者： Olaveson, Tyce W. Gee, Kent L. Brigham Young Univ Dept Phys & Astron Provo UT 84602 USA

Spatiospectral lobes are significant contributors to noise radiated from full-scale tactical aircraft. Prior studies have explored lobe frequency-domain characteristics, but a joint time-frequency domain analysis has the potential to further describe these phenomena and connect them to source-related events in the time waveform. This paper uses acoustical data collected from a 120-microphone array near a T-7A-installed F404 engine to characterize the spatiospectral lobes in combinations of the time, frequency, and spatial domains. An event-based beamforming method is used in conjunction with a wavelet transform to determine propagation angles and event source locations corresponding to each of the lobes. Temporospectral events in the wavelet transform are then analyzed using Markov chains. Finally, spatiospectral maps created from the measured data are decomposed into individual lobes using events in the wavelet transform as a guide. The spatiospectrotemporal combination of these three analyses shows that the lobes originate from multiple, overlapping regions along the jet lipline and that each lobe has its own peak radiation angle. Additionally, events corresponding to the spatiospectral lobes occur intermittently and at different times from each other, leading to bursts of acoustic energy with rapidly changing directivities.

关键词： Broadband Shock Associated Noise Short Time Fourier Transform Wavelet Transform Tracking and Positioning Systems Strouhal Numbers probability density functions Shock Waves Acoustic Noise Boundary Layers Numerical Simulation

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A Comprehensive Review on Stochastic Optimal Power Flow Problems and Solution Methodologies

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IETE TECHNICAL REVIEW 2024年第2期41卷 147-174页

作者： Maheshwari, Ankur Sood, Yog Raj Jaiswal, Supriya Natl Inst Technol Elect Engn Hamirpur Himachal Prades India Natl Inst Technol Dept Elect Engn Hamirpur Himachal Prades India

The deregulation of the electricity market has been accompanied by the growing utilization of unpredictable renewable energy sources (RESs) such as solar, wind, and hydropower plants. Additionally, advancements in energy storage technologies and new energy demands have further contributed to this trend. As a result, the planning and operation of power systems are now surrounded by a higher level of uncertainty. In order to ensure the proper operation of power systems integrated with RESs, modern power systems are equipped with specific vital tools such as optimal power flow (OPF), which regulates generation and demand to achieve specific objectives. Hence, this paper conducts a comprehensive review of recently published research articles focusing on various solution strategies to address OPF problems in the presence of stochastic RESs and power demand. The review encompasses diverse solution methodologies, objective functions, constraints, and distinct techniques to simulate the stochastic behavior of RESs and dynamic loads. Additionally, the paper explores fundamental challenges, identifies critical research gaps, and highlights unexplored areas pertaining to optimal power system operation in the future. This review is essential for system operators who need to assess and pre-plan flexibility competency for their power systems to ensure practical and cost-effective operation under high RESs penetration.

关键词： Metaheuristic optimization algorithms Optimal power flow probability density functions Renewable energy sources Renewable uncertainty

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