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Research on the Generation Mechanism and Suppression method of Aerodynamic Noise in Expansion Cavity Based on hybrid method

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2747-2772页

作者： Haitao Liu Jiaming Wang Xiuliang Zhang Yanji Jiang Qian Xiao School of Mechanotronics and Vehicle Engineering East China Jiaotong UniversityNanchang330013China Suzhou Automotive Research Institue Tsinghua UniversitySuzhou215131China

The expansion chamber serves as the primary silencing structure within the exhaust pipeline.However,it can also act as a sound-emitting structure when subjected to airflow.This article presents a hybrid method for numerically simulating and analyzing the unsteady flow and aerodynamic noise in an expansion chamber under the influence of airflow.A fluid simulation model is established,utilizing the Large Eddy Simulation(LES)method to calculate the unsteady flow within the expansion chamber.The simulation results effectively capture the development and changes of the unsteady flow and vorticity inside the cavity,exhibiting a high level of consistency with experimental observations.To calculate the aerodynamic noise sources within the cavity,the flow field results are integrated using the method of integral interpolation and inserted into the acoustic grid.The acoustic analogy method is then employed to determine the aerodynamic noise sources.An acoustic simulation model is established,and the flow noise source is imported into the sound field grid to calculate the sound pressure at the far-field response point.The calculated sound pressure levels and resonance frequencies show good agreement with the experimental results.To address the issue of airflow regeneration noise within the cavity,perforated tubes are selected as a means of noise suppression.An experimental platformfor airflow regeneration noise is constructed,and experimental samples are processed to analyze and verify the noise suppression effect of perforated tube expansion cavities under different airflow velocities.The research findings indicate that the perforated tube expansion cavity can effectively suppress low-frequency aerodynamic noise within the cavity by impeding the formation of strong shear layers.Moreover,the semi-perforated tube expansion cavity demonstrates the most effective suppression of aerodynamic noise.

关键词： Expansion cavity aerodynamic noise numerical simulation hybrid method perforated tube

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hybrid method integrating machine learning and particle swarm optimization for smart chemical process operations

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Frontiers of Chemical Science and Engineering 2022年第2期16卷 274-287页

作者： Haoqin Fang Jianzhao Zhou Zhenyu Wang Ziqi Qiu Yihua Sun Yue Lin Ke Chen Xiantai Zhou Ming Pan School of Chemical Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China School of Mathematics Sun Yat-Sen UniversityZhuhai 519082China

Modeling and optimization is crucial to smart chemical process operations.However,a large number of nonlinearities must be considered in a typical chemical process according to complex unit operations,chemical reactions and separations.This leads to a great challenge of implementing mechanistic models into industrial-scale problems due to the resulting computational complexity.Thus,this paper presents an efficient hybrid framework of integrating machine learning and particle swarm optimization to overcome the aforementioned difficulties.An industrial propane dehydrogenation process was carried out to demonstrate the validity and efficiency of our method.Firstly,a data set was generated based on process mechanistic simulation validated by industrial data,which provides sufficient and reasonable samples for model training and testing.Secondly,four well-known machine learning methods,namely,K-nearest neighbors,decision tree,support vector machine,and artificial neural network,were compared and used to obtain the prediction models of the processes operation.All of these methods achieved highly accurate model by adjusting model parameters on the basis of high-coverage data and properly features.Finally,optimal process operations were obtained by using the particle swarm optimization approach.

关键词： smart chemical process operations data generation hybrid method machine learning particle swarm optimization

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Impact Increment Based hybrid Reliability Assessment method for Transmission Systems

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 317-328页

作者： Yunkai Lei Yeguang Sun Kai Hou Pei Zhang Lewei Zhu Xiaoxi Yang Xiaonan Liu State Grid Sichuan Economic Research Institute Chengdu610000 China School of Electrical and Information Engineering Tianjin UniversityTianjin 300072China State Grid Customer Service Center Tianjin 300072China School of Electrical and Automation Engineering East China Jiaotong UnviersityNanchang 330052China Maritime College Tianjin University of TechnologyTianjin 300384China College of Economics and Management Southwest Petroleum UniversityChengdu 610000China State Grid Tianjin Electric Power Research Institute Tianjin 300072China

This paper proposes an impact-increment-based hybrid(IIhybrid)reliability assessment approach for power transmission systems.The proposed approach integrates the advantages of the impact-increment-based state enumeration method(IISE)and impact-increment-based Monte Carlo simulation(IIMC)to improve computational efficiency and accuracy.The IISE can efficiently assess the impacts of low-order contingencies.The accuracy is,however,sacrificed as highorder contingencies are usually neglected.The IIMC is more suitable for large-scale contingency spaces compared with IISE,although the calculation process is time-consuming.In this paper,the proposed IIhybrid takes advantage of its strengths while avoiding its shortcomings.The IISE and the IIMC are applied to lower and higher contingency spaces respectively.The high-order contingencies elimination technique proposed in our previous studies is still applicable to the IIhybrid.In addition,efficiency can be controlled by modifying the preset parameters to adapt to various scenarios.Case studies are performed on the IEEE 118-bus test system and PEGASE System.The results show that the proposed approach is more efficient and practicable than traditional methods.

关键词： hybrid method impact-increment reliability assessment transmission system

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hybrid Strategy of Partitioned and Monolithic methods for Solving Strongly Coupled Analysis of Inverse and Direct Piezoelectric and Circuit Coupling

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1371-1386页

作者： Daisuke Ishihara Syunnosuke Nozaki Tomoya Niho Naoto Takayama Department of Intelligent and Control Systems Kyushu Institute of TechnologyFukuokaJapan

The inverse and direct piezoelectric and circuit coupling are widely observed in advanced electro-mechanical systems such as piezoelectric energy harvesters.Existing strongly coupled analysis methods based on direct numerical modeling for this phenomenon can be classified into partitioned or monolithic formulations.Each formulation has its advantages and disadvantages,and the choice depends on the characteristics of each coupled problem.This study proposes a new option:a coupled analysis strategy that combines the best features of the existing formulations,namely,the hybrid partitioned-monolithic method.The analysis of inverse piezoelectricity and the monolithic analysis of direct piezoelectric and circuit interaction are strongly coupled using a partitioned iterative hierarchical algorithm.In a typical benchmark problem of a piezoelectric energy harvester,this research compares the results from the proposed method to those from the conventional strongly coupled partitioned iterative method,discussing the accuracy,stability,and computational cost.The proposed hybrid concept is effective for coupled multi-physics problems,including various coupling conditions.

关键词： Structure-piezoelectric-circuit interaction energy harvesting partitioned method monolithic method hybrid method

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Behavioral Decision-Making of Key Stakeholders in Public-Private Partnerships:A hybrid method and Benefit Distribution Study

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Computer Modeling in Engineering & Sciences 2023年第9期136卷 2895-2934页

作者： Guoshuai Sun Wanyi Zhang Jiuying Dong Shuping Wan Jiao Feng School of Economics and Management Liaoning University of TechnologyJinzhou121001China School of Information Management Jiangxi University of Finance and EconomicsNanchang330032China Post-Doctoral Research Center Zhongda Construction Co.Ltd.Guangzhou510280China School of Science Shanghai Institute of TechnologyShanghai201418China School of Maritime Economics and Management Dalian Maritime UniversityDalian116026China

Public-private partnerships(PPPs)have been used by governments around the world to procure and construct infrastructural amenities.It relies on private sector expertise and funding to achieve this lofty objective.However,given the uncertainties of project management,transparency,accountability,and expropriation,this phenomenon has gained tremendous attention in recent years due to the important role it plays in curbing infrastructural deficits globally.Interestingly,the reasonable benefit distribution scheme in a PPP project is related to the behavior decisionmaking of the government and social capital,aswell as the performance of the project.In this paper,the government and social capital which are the key stakeholders of PPP projects were selected as the research objects.Based on the fuzzy expected value model and game theory,a hybrid method was adopted in this research taking into account the different risk preferences of both public entities and private parties under the fuzzy demand environment.To alleviate the problem of insufficient utilization of social capital in a PPP project,this paper seeks to grasp the relationship that exists between the benefit distribution of stakeholders,their behavioral decision-making,and project performance,given that they impact the performance of both public entities and private parties,as well as assist in maximizing the overall utility of the project.Furthermore,four game models were constructed in this study,while the expected value and opportunity-constrained programming model for optimal decision-making were derived using alternate perspectives of both centralized decision-making and decentralized decision-making.Afterward,the optimal behavioral decision-making of public entities and private parties in four scenarios was discussed and thereafter compared,which led to an ensuing discussion on the benefit distribution system under centralized decision-making.Lastly,based on an example case,the influence of different confidence levels,price,and fuzzy uncertainties of PPP p

关键词： PPP fuzzy expected value game theory behavioral decision-making benefit distribution hybrid method

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Numerical Solution for Neutral Delay Differential Equation of Constant or Proportional Type using hybrid Block method

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Advances in Applied Mathematics and Mechanics 2022年第5期14卷 1138-1160页

作者： Nur Inshirah Naqiah Ismail Zanariah Abdul Majid Norazak Senu Institute for Mathematical Research Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia Department of Mathematics and Statistics Faculty of ScienceUniversiti Putra Malaysia43400 UPM SerdangSelangorMalaysia

Neutral Delay Differential Equation(NDDE)is a differential problem that has regularly existed in numerous occurrences and has represented a significant role in dealing with real-life phenomena,especially on their application in biological and physiological processes.A fifth-order two-point hybrid implicit multistep block method(2PIH5)has been formulated in this research for the numerical solution of Neutral Delay Differential Equation(NDDE).A Taylor series interpolation polynomial has been implemented in the formulation of the proposed 2PIH5.The order,consistency,and zero-stability for 2PIH5 have been illustrated.The analyses of convergence and stability test have been performed and discussed.The initial value problems for the first-order NDDE with constant or proportional delay have been solved using the proposed block method.Some numerical results for the proposed method have been presented to prove the adaptability and applicability of the proposed method in solving NDDE.The proposed method is proved to be comparable with the other existing methods.It is assumed to be reliable and efficient for solving the first-order NDDE with constant or proportional delay.

关键词： Constant delay hybrid method multistep block method neutral delay differential equation proportional delay

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hybrid method for investigation of electromagnetic scattering from conducting target above the randomly rough surface

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Chinese Physics B 2009年第4期18卷 1503-1511页

作者：王蕊郭立新麻军吴振森 School of Science Xidian University

A current based hybrid method （HM） is proposed which combines the method of moment （MOM） with the Kirchhoff approximation （KA） for the analysis of scattering interaction between a two-dimensional （2D） infinitely long conducting target with arbitrary cross section and a one-dimensional （1D） Gaussian rough surface. The electromagnetic scattering region in the HM is split into KA region and MOM region. The electric field integral equation （EFIE） in MOM region （target） is derived, the computational time of the HM depends mainly on the number of unknowns of the target. The bistatic scattering coefficient for the infinitely long cylinder above the rough surface with Gaussian roughness spectrum is calculated, and the numerical results are compared and verified with those obtained by the conventional MOM, which shows the high efficiency of the HM. Finally, the influence of the size, location of the target, the rms height and correlation length of the rough surface on the bistatic scattering coefficient with different polarizations is discussed in detail.

关键词： method of moment hybrid method Gaussian rough surface bistatic scattering

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hybrid method based on flame volume concept for lean blowout limits prediction of aero engine combustors

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Chinese Journal of Aeronautics 2021年第5期34卷 425-437页

作者： Lei SUN Yong HUANG Xiwei WANG Zekun ZHENG Ruixiang WANG Xiang FENG Collaborative Innovation Center of Advanced Air craft-Engine National Key Laboratory of Science and TechnologySchool of Energy and Power EngineeringBeihang UniversityBeijing 102206China School of Aerospace Engineering Tsin^hua UniversityBeijing 100084China China Academy of Aerospace Aerodynamics Beijing 100074China Patent Examination Cooperation(Tianjin)Center of the Patent Office CNIPATianjin 300304China

The Lean Blowout(LBO)limit is crucial for the aircraft engines.The semi-empirical(such as Lefebvre’s LBO model and Flame Volume(FV)model),numerical and hybrid methods are widely utilized for the LBO limit quick prediction.An innovative hybrid method based on the FV concept is proposed.This method can be classified as a semi-empirical/physical based hybrid prediction method.In this hybrid method,it is assumed that the flame volume varies nearly linearly with the fuel/air ratio near the LBO.The flame volume is obtained directly by the numerical simulation using the threshold value of the visible flame boundary as 900 K.Then the final LBO limits is determined by the FV model.On the premise of keeping the good generality of prediction,the hybrid method based on the FV concept can further improve the prediction accuracy.The comparison with the prediction of the existing available methods on fifteen combustors shows that the hybrid method based on the FV concept achieves better prediction accuracy.The prediction uncertainties between the experimental results and the predicted values by the hybrid method based on the FV concept are within about±10%.

关键词： Aircraft engines Combustors Flame volume hybrid method Lean blowout limit Prediction

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High-resolution simulation for rotorcraft aerodynamics in hovering and vertical descending flight using a hybrid method

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Chinese Journal of Aeronautics 2018年第5期31卷 1053-1065页

作者： Liangquan WANG Guohua XU Yongjie SHI National Key Laboratory of Science and Technology on Rotorcraft Aeromeehanics Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

A high-resolution simulation tool for rotorcraft aerodynamics is developed by coupling CFD with a Vorticity Transport Model（VTM）. An Eulerian-based CFD module is used to model the blade near body flowfield, and a Lagrangian-based VTM module is employed for vortex tracking in the far wake. The coupling procedure is implemented by transmitting vortex sources to the VTM module and feeding boundary conditions back to the CFD module. The presented CFD/VTM hybrid solver is firstly validated by hover cases of three different rotor configurations. Simulation results, including the blade surface pressure distribution, rotor downwash, and hover figure of merit, exhibit favorable correlations with available experimental data. Then, a rotor operated in vertical descending flight with a fixed collective pitch is investigated. It is shown that the CFD/VTM coupling method is suitable for rotor wake simulation. Wake instabilities（far wake breakdown in hover and toroidal wake pattern in the vortex ring state） are successfully demonstrated with a moderate computational cost.

关键词： Descending flight hybrid method Rotorcraft Vortex ring state Vorticity transport model

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A hybrid method of Coreference Resolution in Information Security

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Computers, Materials & Continua 2020年第8期64卷 1297-1315页

作者： Yongjin Hu Yuanbo Guo Junxiu Liu Han Zhang Information Engineering University Zhengzhou450000China Intelligent Systems Research Centre School of ComputingEngineering&Intelligent SystemsUlster UniversityMagee CampusNorthern IrelandBT487JLUK Zheng Zhou University Zhengzhou450001China

In the field of information security,a gap exists in the study of coreference resolution of entities.A hybrid method is proposed to solve the problem of coreference resolution in information security.The work consists of two parts:the first extracts all candidates(including noun phrases,pronouns,entities,and nested phrases)from a given document and classifies them;the second is coreference resolution of the selected candidates.In the first part,a method combining rules with a deep learning model(Dictionary BiLSTM-Attention-CRF,or DBAC)is proposed to extract all candidates in the text and classify them.In the DBAC model,the domain dictionary matching mechanism is introduced,and new features of words and their contexts are obtained according to the domain dictionary.In this way,full use can be made of the entities and entity-type information contained in the domain dictionary,which can help solve the recognition problem of both rare and long entities.In the second part,candidates are divided into pronoun candidates and noun phrase candidates according to the part of speech,and the coreference resolution of pronoun candidates is solved by making rules and coreference resolution of noun phrase candidates by machine learning.Finally,a dataset is created with which to evaluate our methods using information security data.The experimental results show that the proposed model exhibits better performance than the other baseline models.

关键词： Coreference resolution hybrid method rules BiLSTM-Attention-CRF information security

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