bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat transfer enhancement mechanism of jet impingement on aeroengine curved surface using large eddy simulation
Authors: Li Qin , Dong Wei , Cai Xuecheng , Yang Xiaofeng , Zheng Haoran 
Published: February 2021

Abstract
Jet impingement is widely used in anti-icing and de-icing of aeroengines. To improve the efficiency of anti-icing and de-icing, heat transfer in jet impingement flow should be further enhanced. By using large eddy simulation (LES) method, jet impingement flow was analysed in time-domain and spatial-domain. It was revealed that the jet flow has quasi-periodic characteristics in time, and heat transfer is dominated by vortex structure. In addition, the impinged surface curvature has a certain influence on the spatial distribution of Nusselt number. Better heat transfer effect can be achieved by inducing more vortices and applying proper surface curvature.
Overview of surfing aircraft vortices for energy
Authors: Zhao Yixin , Wu Hanyu , Zhang Qiang , Cheng Qing 
Published: February 2021

Abstract
Surfing Aircraft Vortices for Energy (SAVE) refers to the behavior that an aircraft “rides” on the vortex of the front aircraft just like the formation flying of migratory birds and it can also provide guidance for the aircraft that is difficult to avoid entering the front vortex, reduce the incidence of flight accidents caused by the vortex, and improve the safe operation ability of civil aviation. The technology has the advantages of saving energy and increasing range, which is a hot issue in the field of aviation research. Firstly, this paper analyzes the main research contents, technological developments and applications in the field of SAVE at home and abroad. Then discusses the key technologies of SAVE such as aerodynamic principles, control of SAVE, safety guarantee, path planning, and related experimental verification technologies. Finally, the development and application trend of SAVE technology in military and civil aviation fields and its corresponding benefits brought by it will be pointed out.
Study on a quality assessment method for rocket body structure based on product quality DNA
Authors: Jiayu Yao , Haijiang Liu 
Published: February 2021

Abstract
Under the current production mode of multiple varieties and small batches, the traditional post-event quality assessment method is still used in the manufacture of rocket body structure in China. In order to solve the problem that this method can not fully reflect the quality of each step in each process, a quality assessment method for rocket body structure based on product quality DNA is proposed in this paper, which converts the assessment of product quality into the analysis of product quality DNA. This method comprehensively assesses the quality of each process and each step in each process by searching the assessment knowledge base based on product quality DNA. Based on the principle of biological DNA, this paper combines the idea of product gene with product quality, and constructs a model of product quality DNA from three structural levels(basic structure, double helix structure and superhelix structure). This paper takes a weld of a rocket body structure as an example and assesses the quality of this weld by using the quality assessment method for rocket body structure based on product quality DNA. The results show that the quality of the weld is assessed as “good”.
A Review of High Precision Finite Element Modelling Methods for Light and Small UAS
Authors: Yongjie Zhang , Yingjie Huang , Kang Cao , Yafeng Wang , Yazhou Guo , Jizhen Wang , Xiaochuan Liu 
Published: February 2021

Abstract
In the dynamic mechanics analysis of light and small unmanned aerial systems (UAS), The importance of the high-precision modelling of UAS is unquestionable. Modelling can be classified into 3D geometric model modelling and finite element model modelling, of which the finite element model modelling is mainly divided into four parts: discretization, connection modelling, contact modelling and material attribute definition. This review summarizes the existing modelling methods of light and small UAS, and provides the basic methods and modelling methods for the simulation calculation of light and small UAS. Implications for practice and future research are provided.
Improved weighted NND scheme for shock-capturing
Authors: Li Chen , Chen Jianqiang , Yuan Xianxu , Liu Pengxin , Sun Dong , Qilong Guo 
Published: February 2021

Abstract
Aimed at decreasing the numerical dissipation of weighted non-oscillatory and non-free-parameter dissipation (WNND) scheme, we present an improved counterpart for shock-capturing. The new algorithm is based on the framework of Z-type weighting procedure with new local and global smoothness indicators. The performances of the proposed scheme are evaluated on several numerical tests governed by one-dimensional Euler equations. Numerical results indicate that the improved WNND scheme has advantages over the original WNND and third-order WENO-JS and WENO-Z schemes.
Application of colour fluorescent oil flow visualization for a high speed cavity
Authors: He Binhua , Li Guoshuai , Zhou Fangqi , Liu Dawei , Xiang Xie 
Published: February 2021

Abstract
For studying the complex flow structure of a high speed cavity, including shear layer, separation, reattachment and vortex, the single-color fluorescent oil flow visualization system in the 0.6m×0.6m trisonic wind tunnel of China Aerodynamic Research Development Centre was enhanced. Different portions of the cavity such as its bottom wall, left and right side walls, front and rear walls and area outside the cavity utilized different oil films with different fluorescent particles to visualize the flow mixing more effectively in the cavity. Specialized ultraviolet light sources are used to enhance the oil flow image contrast. Additionally, to ensure the oil film follows the surface streamlines and indicates the skin friction lines more accurately, the thickness and viscosity of the oil film are well controlled. A high-speed cavity wind tunnel test was conducted to validate the improved oil flow visualization system at Mach number ranging from 0.6 to 2.0. The experimental result shows that the improved oil flow system can effectively visualize complex flow patterns of the cavity flow at all Mach numbers. Colour fluorescent oil flow visualization system established in the present study provides a capability to visualize the flow mixing phenomenon in cavity flows with a high image contrast.
Investigation on the depth effects of the micro-grooves on the suppression of the second modes in the hypersonic boundary layer
Authors: Guo Qilong , Li Chen , Tu Guohua , Chen Jianqiang , Wan Bingbing , Liu Yong 
Published: February 2021

Abstract
The transition of the hypersonic boundary layer and the corresponding control have been extensively interested since the strong engineer background. In the present work, a hypersonic boundary layer over a flat plate of Mach 6 is computed using the high-order finite-difference scheme. The influences of the two-dimensional micro-grooves on the evolution of the second-mode instability wave are investigated. The comparison is carried out between different depths of the micro-groove. The results indicate that the actual control effect does not significantly vary with the depths under the condition with large grooves. The DNS prediction show different results with the theoretical model for the acoustic reflection coefficient. It is suggested that new model should be derived to guide the design and optimize of the parameters of the micro-groove.
Research on parameter adjustment method of servo controller based on genetic algorithm
Authors: Tian Huan , Dong Wenyong , Xu Yafen , Gao Yuan , Fang Cheng 
Published: February 2021

Abstract
In view of the problem that the controller parameters of the servo system of launch vehicle cannot be adjusted after installation, the parameter adjustment method of the servo system controller parameters is designed by the optimization method based on the genetic algorithm. Set the scale, the notch frequency and the damping coefficient as the variable to be adjusted. The adjusted ITAE guideline module is the error criterion, and the notch filter parameters are adjusted. The experimental verification results of servo system simulation test bench show that the method of this paper can effectively optimize the parameters of servo system controller and improve the quality of servo system.
Thrust control when landing a ship-based aircraft
Authors: Semakov Sergei 
Published: February 2021

Abstract
We consider a landing on an aircraft carrier. We propose a scheme for calculating the probability of go-around due to disengaging the arresting gear and a scheme for calculating the maximum descent of the aircraft trajectory with respect to the deck level immediately after leaving the deck. The main control parameter is the moment of increase in aircraft’s thrust before touching the deck. The requirements imposed on the probability of go-around and the maximum descent of the aircraft trajectory determine the possible range for the moment of increase in aircraft’s thrust. Proposing the scheme for calculating the probability of go-around, we use our previously obtained results related to finding the probability of a successful aircraft landing. We present the numerical results for the real aircraft when landing on the real aircraft carrier.
Simulation and analysis of multi-frequency signal superposition with scattering center model
Authors: Yang R P , Wang X , Liu C H , Liu Y , Liu Y 
Published: February 2021

Abstract
In this paper, the superposition of time domain scattering signal with different frequency is analyzed. Simulation results shows that the peak value of the sum signal is able to be approximately estimated from scattering center model. Besides, the results show that energy of multi-frequency scattering signal has the potential to accumulate in time domain, which might help to design new kinds of signal to recognize target and resist noise at the same time.
Simulation detection based on single photon quantum key distribution protocol
Authors: Liu X N , Hu C C , Yin M J , Jin L 
Published: February 2021

Abstract
With the continuous development of quantum communication in recent years, quantum key distribution (QKD) has also become a key technology in the field of quantum communication. Due to the limitation of physical resources and experimental conditions, the effectiveness of different communication protocols cannot be accurately analyzed. To solve this problem, a protocol simulation method is proposed, BB84 and B92 protocols are simulated and analyzed on a classic computer by this method. On the Eclipse IDE Developers platform, the simulation program of the quantum communication protocol was written using Java language, the simulation process under the ideal environment and the eavesdropping environment was analyzed with emphasis. The simulation results show that the key distribution efficiency of BB84 is about 50% without eavesdroppers, which is much higher than 25% of B92, and the key distribution efficiency under eavesdropping conditions is about 25% and 18%. The experimental results are consistent with theoretical expectations, verifying the correctness of the protocol simulation, and also proving the feasibility of using computers for quantum communication protocol simulation.
Effect of interleaving on the performances of the MAP turbo decoder controlled by the IHDA and CE Stopping criteria
Authors: Ouardi Aissa 
Published: February 2021

Abstract
In this article, we present the effect of interleaver size on the performance of a turbo decoder using a stopping criterion to reduce complexity and decoding time. We choose the two criteria CE and IHDA. The interleavers used are pseudo-random interleavers, S-Random, of sizes 5120 and 1280. The simulation results show that the IHDA criterion uses the lowest average iteration number in medium and high Signal-to-Noise Ratios SNR. Increasing the size of the interleaver also provides significant coding gain
DOA estimation based on fractional low-order multi-sensor time-frequency analysis in heavy tailed noise
Authors: Xu Jing , Sun Bin , Cao Yang , Hong Wei 
Published: February 2021

Abstract
In order to improve the performance of Direction-of-arrival (DOA) estimation in heavy-tailed noise, a novel DOA estimation method based on fractional low-order multi-sensor time-frequency distribution is proposed. We first use the high-resolution of the fractional low-order multi-sensor time-frequency analysis (FLOM-MTFA) to obtain the time-frequency matrices of the array signal. Then, the high-energy points of the fractional low-order multi-sensor time-frequency matrices is selected to improve the MSNR. We finally compute the averaged FLOM-MTFA matrix and exploit estimation signal parameter via rotational invariance techniques to estimate DOA. Theoretical analysis and simulation results show that the proposed method can effectively estimate DOA in heavy tailed noise.
Research on key technologies for 2μm band of thulium-doped fiber laser
Authors: Zhang Ning , Sun Huijuan , Luo Yang 
Published: February 2021

Abstract
Abstract The gain material of 2μm wavelength thulium-doped fiber laser is a thulium-doped fiber doped with rare earth element thulium. Rare earth doped optical fiber as gain medium is the basic structure of optical fiber laser. This type of laser is mainly composed of pump source, coupler, gain optical fiber doped with rare earth elements, cavity and other optical devices. The pump source is generally a combination of one or several high-power laser diodes. The light emitted by the pump source enters the gain optical fiber doped with rare earth elements through a certain pumping mode. The inversion of the number of particles occurs when the doped optical fibers absorb photons, and then the light waves stimulated from the doped optical fibers are emitted by the laser after the oscillation. Since the connection structure and parameters between optical fibers and optical components can be maintained stable over a long period of time, thulium-doped lasers do not need to be maintained regularly and are based on output power. They have smaller volume and weight, lighter weight and longer life than solid-state lasers. However, in general, the power of a 2μm wavelength thumbium-doped fiber laser is not too high, while a high-power 2μm wavelength thumbium-doped fiber laser can meet people’s needs and play a greater role. Therefore, improving the power of 2μm wavelength thumbium-doped fiber laser is an important direction for the development of thumbium-doped fiber laser. The energy level structure of thulium ion is analyzed, the doping concentration of thulium ion is studied, and the method to increase the power of a 2μm wavelength thulium-doped fiber laser is given.
A novel recommendation algorithm with knowledge graph
Authors: Liu L , Zhang P 
Published: February 2021

Abstract
Personalized recommendation is an important topic in recommendation algorithm research. Traditional collaborative filtering recommendation algorithms suffer the sparseness and cold start problems. Existing knowledge graph based recommendation algorithms miss the high-order similarity at the subgraph level. This paper introduces a RNN-based distributed representation model of knowledge graph called KG-GRU, which uses a sequence containing nodes and relationships to model the subgraph similarity in the same embedded vector space. Then, a personalized recommendation algorithm based on knowledge graph called KG-GRU4Rec, is proposed. KG-GRU4Rec implements an end-to-end predictive user rating model. Experimental results demonstrate that KG-GRU learns more accurate knowledge about entities and relationships in the graph and KG-GRU4Rec outperforms the comparison algorithm in both hit ratio and average reciprocal ranking.
Toward secure refactoring of object-oriented programs
Authors: Mahmoud Marwan 
Published: February 2021

Abstract
Security is a significant issue in software systems. The initially secure design of a software system could be at risk of a refactoring transformation. Consequently, via a refactoring transformation, the software could be considered vulnerable, and the refactoring process can undergo security-aware refactoring. This work deals with three security approaches to assist programmers in refactoring their software systems while simultaneously sustaining or possibly improving the security of their software system. In addition, this work deals with security-aware refactoring at the design stage rather than refactoring that requires a full source code. The main aim of this work is to provide programmers with knowledge about secure refactoring processes to improve the long-term maintainability of the software system in a secure way while sustaining the external behavior of the system.
Numerical Simulation of the Fracture Characteristics of Copper EFP with Different Constitutive Models
Authors: Ding Li , Jiang Jianwei , Men Jianbing , Wang Shuyou 
Published: February 2021

Abstract
With three different constitutive model, LS-DYNA hydro code is applied to simulate the forming and fracture characteristics of Copper EFP. By comparison of numerical results of different models, the appropriate constitutive model to simulate the complete and fracture EFPs can be obtained. By comparison of experimental and numerical results, it can be concluded that Steinberg-Guinan constitutive model gives the best result to predict the complete EFP’s forming shape with minimum error, while Johnson-Cook constitutive model with failure model and h-adaptive algorithm is the most suitable method to predict the fracture of EFP in axial direction. The research results are important and significant in the deign of shaped charge, which could provide a guideline to predict the fracture of EFP in numerical simulation.
Model and Empirical Research on Risk Assessment Based on Second-Order Monte Carlo Simulation
Authors: Gao Xiaohong , Liu Jian 
Published: February 2021

Abstract
First order Monte Carlo simulation simplifies the processing of input variables, while the analysis results can not meet the needs of major decisions. Second order Monte Carlo simulation divides the input variables into uncertainty and variability, which can help decision makers understand the impact of different input variables on the results and the credibility of the evaluation results. On the basic of analysing the two methods, an enterprise’s investment project was taken as an example; using point estimation method, first-order Monte Carlo simulation and second-order Monte Carlo methods respectively for risk assessment and comparison. Finally, conclusions and recommendations are given for using second-order Monte Carlo simulation for risk assessment of Investment Project Decision-making.
Ternary Sentiment Classification of Airline Passengers’ Twitter Text Based on BERT
Authors: Xie Yungao , Wen Hong , Yang Qing 
Published: February 2021

Abstract
Traditional word vector generation model cannot solve the polysemy problem of word representation in Twitter text, so, a method is presented here, firstly, by using Bidirectional Encoder Representations from Transformers (BERT), the semantic feature vector of the text can be obtained, and then, the feature vector is inputted into the Softmax classifier to implement the sentiment classification of Twitter text. The experimental datasets are source from passengers’ Twitter comments of USA six airlines, the sentiment classification model based on Embeddings from Language Model (ELMo) as the experimental control group. The experimental results indicate that the proposed model is advantage over the experimental control group by using F1-score as the evaluation index.
Sensorless Control of Switched Reluctance Motor Based on Matlab/Simulink Simulation
Authors: Gao Jinjian , Sun Baojiang , Huo Wenli 
Published: February 2021

Abstract
This article mainly introduces the acquisition of the position information of the switched reluctance motor through the inductance, which can make the switched reluctance motor(SRM) correct commutation. The main method is to apply high-frequency and low-duty pulse voltages to the two non-conducting phases of the switched reluctance motor when the motor is in low-speed operation, so that the non-conducting phase generates a response current through the rising slope of the response current The current change rate is obtained by the difference with the falling slope, and then the current change rate is converted into inductance through a formula, and whether the inductance reaches the inductance threshold is judged whether it reaches the commutation position, and the motor is subjected to timely and accurate commutation processing. This method is realized by matlab/simulink simulation, and combined with the high-speed inductance method obtained by the flux ratio current, to realize the position sensorless technology combined with the inductance method in the full speed cycle, and the simulation verifies that the low-speed and high-speed algorithms can be smooth Switch, and can realize its commutation control function, and It provides simulation support for applications such as lawn mower.
Dynamic Aircraft Conflict Alert Based on the Markov Decision Process and Simulation of Actual Flight Data
Authors: Li Jie , Song Ruiliang , Zhang Haipeng 
Published: February 2021

Abstract
As air traffic flow continues growing, the risk of collision between aircraft is also increasing as well. In order to ensure efficiency of airspace would not reduce due to the increase of the conflict, and thus the accuracy of alerts also has higher requirements. Traditional conflict alerts based on the static threshold method will have a great flight separation redundancy, resulting in reduced operating efficiency of airspace. So it’s necessary to study the dynamic threshold alerts approach based on actual flight scenes, which can dynamically adjust the threshold and improve operational efficiency. First in this article, Markov decision processes were introduced. And then proposed a dynamic threshold alert method based on the Markov decision process. Finally, the analysis of alert results were performed through simulation of actual flight data. The results show that this method can reduce the false alert rate and improve the performance of the alert system under the premise of ensuring flight safety.
Data-driven Modeling of the Methane Adsorption Isotherm on Coal Using Supervised Learning Methods: A Comparative Study
Authors: Feng Qihong , Wang Jiaming , Zhang Jiyuan , Zhang Xianmin 
Published: February 2021

Abstract
Methane adsorption isotherm on coals is key to the development of coalbed methane (CBM). Laboratory measurement of adsorption isotherm is time-consuming. This paper presents a comparative study on the accuracy and robustness of seven supervised learning (SL) methods in estimating the methane adsorption isotherm based on coal properties. The SL methods used include the Gaussian process regression (GPR), kernel ridge regression (KRR), classifier and regression tree (CART) and four ensemble decision tree methods (random forests (RF), Adaboost, gradient boosting decision tree (GBDT) and extreme boosting (XGBoost)). The results show that all these SL methods are capable of correlating methane adsorption amounts with the feature variables with reasonable accuracies in the training stage. However, the KRR, GBDT and XGBoost are demonstrated to outperform other SL techniques in terms of the robustness and generalization capability, which therefore are recommended for fast estimation of the methane adsorption isotherms on coals.