The study of the development cost of general aviation aircraft is limited by small samples with many cost-driven factors. This paper investigates a parametric modeling method for prediction of the development cost of ...The study of the development cost of general aviation aircraft is limited by small samples with many cost-driven factors. This paper investigates a parametric modeling method for prediction of the development cost of general aviation aircraft. The proposed technique depends on some principal components, acquired by utilizing P value analysis and gray correlation analysis. According to these principal components, the corresponding linear regression and BP neural network models are established respectively. The feasibility and accuracy of the P value analysis are verified by comparing results of model fitting and prediction. A sensitivity analysis related to model precision and suitability is discussed in detail. Results obtained in this study show that the proposed method not only has a certain degree of versatility, but also provides a preliminary prediction of the development cost of general aviation aircraft.展开更多
Obtaining accurate development cost estimation results of general aviation aircraft is crucial for companies to adopt the best strategy in the development process.To address this problem,this paper proposes a combinat...Obtaining accurate development cost estimation results of general aviation aircraft is crucial for companies to adopt the best strategy in the development process.To address this problem,this paper proposes a combination of three commonly used single prediction methods.The optimal weight values of the three single prediction methods are determined by utilizing the shortest ideal point method.Ten cost datasets collected from literature are utilized for fitting and testing the combined prediction method,and the weight coefficients of the three individual prediction methods are calculated as 0.6859,0.0035 and 0.3106,respectively.The results of this study indicate that the developed method has better fitting and estimation accuracy than that of the three individual methods,with average fitting and predicting error values of 2.60%and 6.43%,respectively.Additionally,the cost data of military and civil aircraft development from literature are collected for verification.The results further confirm that the proposed method is not only superior to the single prediction methods in terms of high precision but has wider applications.More importantly,this research can provide important reference for general aviation aircraft companies in term of product cost planning and corporate sales strategies.展开更多
In this paper,an analytical time domain formulation based on Ffowcs Williams-Hawkings(FW-H)equation is derived for the prediction of the acoustic velocity field generated by moving bodies.This provides the imposition ...In this paper,an analytical time domain formulation based on Ffowcs Williams-Hawkings(FW-H)equation is derived for the prediction of the acoustic velocity field generated by moving bodies.This provides the imposition of the Neumann boundary condition on a rigid scattering surface.In order to calculate the scattering sound pressure of the duct,a thin-body boundary element method(BEM)has been proposed.The radiate sound pressure is calculated using the acoustic analogy FW-H equation.The scattering effect of the duct wall on the propagation of the sound wave is presented using the thin-body BEM.Computational results for a pulsating sphere,dipole source,and a tail rotor verify the method.The sound pressure directivity and scattering effect are shown to demonstrate the applicability and validity of the approach.展开更多
In the field of sequencing of secret number,an important problem is how to establish an efficient and secure protocol for sorting the secret number.As a powerful tool in solving privacy sequencing problems,secure mult...In the field of sequencing of secret number,an important problem is how to establish an efficient and secure protocol for sorting the secret number.As a powerful tool in solving privacy sequencing problems,secure multipart computation is more and more popular in anonymous voting and online auction.In the present study,related secure computation protocol for sequencing problem is not many by far.In order to improve the efficiency and safety,we propose a security sequencing protocol based on homomorphic encryption.We also give analysis of correctness and security to highlight its feasibility.展开更多
基金supported by the National Postdoctoral Program for Innovative Talents, Postdoctoral Science Foundation of China (No. 2017M610740)supports from Hefei General Aviation Research Institute, Beihang University
文摘The study of the development cost of general aviation aircraft is limited by small samples with many cost-driven factors. This paper investigates a parametric modeling method for prediction of the development cost of general aviation aircraft. The proposed technique depends on some principal components, acquired by utilizing P value analysis and gray correlation analysis. According to these principal components, the corresponding linear regression and BP neural network models are established respectively. The feasibility and accuracy of the P value analysis are verified by comparing results of model fitting and prediction. A sensitivity analysis related to model precision and suitability is discussed in detail. Results obtained in this study show that the proposed method not only has a certain degree of versatility, but also provides a preliminary prediction of the development cost of general aviation aircraft.
基金the National Postdoctoral Program for Innovative Talents,Postdoctoral Science Foundation of China(No.2017M610740)the supports from Hefei General Aviation Research Institute,Beihang University。
文摘Obtaining accurate development cost estimation results of general aviation aircraft is crucial for companies to adopt the best strategy in the development process.To address this problem,this paper proposes a combination of three commonly used single prediction methods.The optimal weight values of the three single prediction methods are determined by utilizing the shortest ideal point method.Ten cost datasets collected from literature are utilized for fitting and testing the combined prediction method,and the weight coefficients of the three individual prediction methods are calculated as 0.6859,0.0035 and 0.3106,respectively.The results of this study indicate that the developed method has better fitting and estimation accuracy than that of the three individual methods,with average fitting and predicting error values of 2.60%and 6.43%,respectively.Additionally,the cost data of military and civil aircraft development from literature are collected for verification.The results further confirm that the proposed method is not only superior to the single prediction methods in terms of high precision but has wider applications.More importantly,this research can provide important reference for general aviation aircraft companies in term of product cost planning and corporate sales strategies.
文摘In this paper,an analytical time domain formulation based on Ffowcs Williams-Hawkings(FW-H)equation is derived for the prediction of the acoustic velocity field generated by moving bodies.This provides the imposition of the Neumann boundary condition on a rigid scattering surface.In order to calculate the scattering sound pressure of the duct,a thin-body boundary element method(BEM)has been proposed.The radiate sound pressure is calculated using the acoustic analogy FW-H equation.The scattering effect of the duct wall on the propagation of the sound wave is presented using the thin-body BEM.Computational results for a pulsating sphere,dipole source,and a tail rotor verify the method.The sound pressure directivity and scattering effect are shown to demonstrate the applicability and validity of the approach.
基金supported by the National Natural Science Foundation of China under Grant No.51307004
文摘In the field of sequencing of secret number,an important problem is how to establish an efficient and secure protocol for sorting the secret number.As a powerful tool in solving privacy sequencing problems,secure multipart computation is more and more popular in anonymous voting and online auction.In the present study,related secure computation protocol for sequencing problem is not many by far.In order to improve the efficiency and safety,we propose a security sequencing protocol based on homomorphic encryption.We also give analysis of correctness and security to highlight its feasibility.
