Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-...Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.展开更多
To increase the convergence rate of the improved normalized subband adaptive filter,a simple but effective method is presented to change the reusing order of coefficient vectors of the adaptive filter. At the beginnin...To increase the convergence rate of the improved normalized subband adaptive filter,a simple but effective method is presented to change the reusing order of coefficient vectors of the adaptive filter. At the beginning of adaptation the algorithmjust uses its current coefficient vector to update the adaptive filter to maintain fast convergence rate,while in steady state it employs several most recent coefficient vectors to update the adaptive filter to reduce misalignment. Simulation results showthat the proposed algorithmcan obtain both fast convergence rate and small steady-state misalignment.展开更多
Quantum chemistry parameters of 28 alkyl（1-phenylsulfonyl） cycloalkane-carboxy-lates were computed at the 6-31G＊ level in fully optimal manner using B3LYP method of density functional theory （DFT）. With GQSARF2.0...Quantum chemistry parameters of 28 alkyl（1-phenylsulfonyl） cycloalkane-carboxy-lates were computed at the 6-31G＊ level in fully optimal manner using B3LYP method of density functional theory （DFT）. With GQSARF2.0 program, the correlation equations that can predict n-octanol/water partition coefficient （lgKow） were developed using the structural and thermodynamic parameters of 28 alkyl（1-phenylsulfonyl） cycloalkane-carboxylates with experimental data of lgKow as theoretical descriptors; the correlation coefficient （R^2） was 0.9452 and the cross-validation squared correlation coefficient （Rcv^2） 0.9312. Furthermore, a four-variable model from MEDV was obtained, of which R2 = 0.9497 and Rov^2 =0.9388. The models were validated by variance inflation factor （VIF） and t-test. Cross-validation indicates that the correlation and predicting ability of the model based on both DFT method and MEDV are more advantageous than those obtained from semi-empirical AM1 method.展开更多
This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the prop...This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.展开更多
A new approach for the prediction of lift,drag,and moment coefficients is presented.This approach is based on the support vector machines(SVMs)methodology and an optimization meta-heuristic algorithm called extended g...A new approach for the prediction of lift,drag,and moment coefficients is presented.This approach is based on the support vector machines(SVMs)methodology and an optimization meta-heuristic algorithm called extended great deluge(EGD).The novelty of this approach is the hybridization between the SVM and the EGD algorithm.The EGD is used to optimize the SVM parameters.The training and validation of this new identification approach is realized using the aerodynamic coefficients of an ATR-42 wing model.The aerodynamic coefficients data are obtained with the XFoil software and experimental tests using the Price-Paidoussis wind tunnel.The predicted results with our approach are compared with those from the XFoil software and experimental results for different flight cases of angles of attack and Mach numbers.The main pur-pose of this methodology is to rapidly Predict aircraft aerodynamic coefficients.展开更多
The method of singular coefficient of water inrush to achieve safety mining has limitation and one sidedness. Aiming at the problem above, large amounts of data about water inrush were collected. Then the data, includ...The method of singular coefficient of water inrush to achieve safety mining has limitation and one sidedness. Aiming at the problem above, large amounts of data about water inrush were collected. Then the data, including the maximum water inrush, water inrush coefficient and water abundance in aquifers of working face, were processed by the statistical analysis. The analysis results indicate that both water inrush coefficient and water abundance in aquifers should be taken into consideration when evaluating the danger of water inrush from coal seam floor. The prediction model of safe-mining evaluation grade was built by using the support vector machine, and the result shows that this model has high classification accuracy. A feasible classification system of water-inrush safety evaluation can be got by using the data visualization method which makes the implicit support vector machine models explicit.展开更多
In this paper, several approaches for calculation of the effective tensor coefficient for domains with inclusions have been proposed. The limits of the approaches using are found. The series of numerical experiments a...In this paper, several approaches for calculation of the effective tensor coefficient for domains with inclusions have been proposed. The limits of the approaches using are found. The series of numerical experiments are made on the different frequencies, for different inclusions location and boundary conditions for the contrast properties of the matrix and inclusion materials.展开更多
In this study, a reliability index vector formula is proposed for series system with two failure modes in term of the concept of reliability index vector and equivalent failure modes. Firstly, the reliability index ve...In this study, a reliability index vector formula is proposed for series system with two failure modes in term of the concept of reliability index vector and equivalent failure modes. Firstly, the reliability index vector is introduced to determine the correlation coefficient between two failure modes, and then, the reliability index vector of a series system can be obtained. Several numerical cases and an analysis on offshore platform are performed, and the results show that this scheme provided here has better computational accuracy, and its calculation process is simpler for the series systems reliability calculations compared with the other methods. Also this scheme is more convenient for the engineering applications.展开更多
We study the quantum theory of the mass-less vector fields on the Rindler space. We evaluate the Bogoliubov coefficients by means of a new technique based upon the use of light-front coordinates and Mellin transform. ...We study the quantum theory of the mass-less vector fields on the Rindler space. We evaluate the Bogoliubov coefficients by means of a new technique based upon the use of light-front coordinates and Mellin transform. We briefly comment about the ensuing Unruh effect and its consequences.展开更多
This research paper presents a numerical study on the flow characteristics and performance of a baffled shock two-dimensional vector nozzle. The baffled shock vector nozzle is a type of fluid thrust vectoring nozzle t...This research paper presents a numerical study on the flow characteristics and performance of a baffled shock two-dimensional vector nozzle. The baffled shock vector nozzle is a type of fluid thrust vectoring nozzle that uses a secondary injection to deflect the primary flow and generate a vector angle. The fluid thrust vectoring technology is regarded as a key technology for the development of very low detectable vehicles because of its advantages, such as fast response, lightweight, and good stealth performance. The main objectives of this study are to investigate the effects of various parameters such as slot interval distance, slot width, injection angle, nozzle pressure ratio, secondary flow pressure ratio, and outflow Mach number on the deflection angle, thrust coefficient, thrust efficiency, and secondary flow ratio of the nozzle. The numerical simulations are carried out using the k-epsilon turbulence model, which is validated by comparing it with experimental data. The results indicate that optimizing the slot interval distance and width, increasing the injection angle, adjusting the nozzle pressure ratio and secondary flow pressure ratio, and controlling the outflow Mach number can enhance the nozzle performance. The results also reveal the complex flow phenomena inside the nozzle, such as shock wave interactions, flow separation and reattachment, and boundary layer effects. The study provides a comprehensive understanding of the flow characteristics and performance of a baffled shock two-dimensional vector nozzle and offers some guidance for its design and optimization.展开更多
为了准确识别气体绝缘开关柜(gas insulated switchgear,GIS)设备的异常工况,提出了一种基于加权梅尔频率谱系数单类支持向量机(Mel frequency cestrum coefficient-one class support vector machine,MFCC-OCSVM)和贝叶斯优化的门控循...为了准确识别气体绝缘开关柜(gas insulated switchgear,GIS)设备的异常工况,提出了一种基于加权梅尔频率谱系数单类支持向量机(Mel frequency cestrum coefficient-one class support vector machine,MFCC-OCSVM)和贝叶斯优化的门控循环单元(bidirectional gate recurrent unit,BiGRU)声纹识别算法。首先,利用基于F统计量的MFCC对声纹数据进行加权特征提取,突出重要特征并减弱噪声的影响,然后利用OCSVM对加权后的特征进行异常检测并去除异常值,提高数据质量。为解决样本不平衡问题,采用合成少数类过采样技术(synthetic minority over-sampling technique,SMOTE)进行声纹样本的均衡。最后,应用基于贝叶斯优化的BiGRU模型进行声纹识别。以某气体绝缘全封闭组合电器(gas insulated switchgear,GIS)为例,采集了20类不同工况下操纵机构的声音样本,与多种经典分类模型进行对比。结果显示,所提算法取得的最高平均识别准确率达到了92.8%,相比于自适应增强、朴素贝叶斯和线性判别分析算法分别提升了30.1%、14.7%和11.5%。通过消融实验进一步评估和验证了所提算法各个流程对声纹识别的实际效果和性能影响,研究成果可为GIS设备异常工况的声纹识别提供高效技术路线。展开更多
基金Project supported by the BUPT Excellent Ph.D.Students Foundation(Grant No.CX2019201)the National Natural Science Foundation of China(Grant Nos.11772017 and 11805020)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(Grant No.IPOC:2017ZZ05)the Fundamental Research Funds for the Central Universities of China(Grant No.2011BUPTYB02)。
文摘Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.
基金Supported by the National Natural Science Foundation of China( 61471251 61101217)the Natural Science Foundation of Jiangsu Province of China (BK20131164)
文摘To increase the convergence rate of the improved normalized subband adaptive filter,a simple but effective method is presented to change the reusing order of coefficient vectors of the adaptive filter. At the beginning of adaptation the algorithmjust uses its current coefficient vector to update the adaptive filter to maintain fast convergence rate,while in steady state it employs several most recent coefficient vectors to update the adaptive filter to reduce misalignment. Simulation results showthat the proposed algorithmcan obtain both fast convergence rate and small steady-state misalignment.
基金Supported by the Key Program of National Natural Science Foundation of China (No. 20737001)the National Science Foundation for Post-doctoral Scientists of China (No. 2003033486)
文摘Quantum chemistry parameters of 28 alkyl（1-phenylsulfonyl） cycloalkane-carboxy-lates were computed at the 6-31G＊ level in fully optimal manner using B3LYP method of density functional theory （DFT）. With GQSARF2.0 program, the correlation equations that can predict n-octanol/water partition coefficient （lgKow） were developed using the structural and thermodynamic parameters of 28 alkyl（1-phenylsulfonyl） cycloalkane-carboxylates with experimental data of lgKow as theoretical descriptors; the correlation coefficient （R^2） was 0.9452 and the cross-validation squared correlation coefficient （Rcv^2） 0.9312. Furthermore, a four-variable model from MEDV was obtained, of which R2 = 0.9497 and Rov^2 =0.9388. The models were validated by variance inflation factor （VIF） and t-test. Cross-validation indicates that the correlation and predicting ability of the model based on both DFT method and MEDV are more advantageous than those obtained from semi-empirical AM1 method.
文摘This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.
基金funded by the Natural Sciences and Engineering Research Council of Canada(NSERC)in the frame of the Canada Research Chair for Aircraft Modeling and Simulation Technologies
文摘A new approach for the prediction of lift,drag,and moment coefficients is presented.This approach is based on the support vector machines(SVMs)methodology and an optimization meta-heuristic algorithm called extended great deluge(EGD).The novelty of this approach is the hybridization between the SVM and the EGD algorithm.The EGD is used to optimize the SVM parameters.The training and validation of this new identification approach is realized using the aerodynamic coefficients of an ATR-42 wing model.The aerodynamic coefficients data are obtained with the XFoil software and experimental tests using the Price-Paidoussis wind tunnel.The predicted results with our approach are compared with those from the XFoil software and experimental results for different flight cases of angles of attack and Mach numbers.The main pur-pose of this methodology is to rapidly Predict aircraft aerodynamic coefficients.
基金Financial supports for this work, provided by National Natural Key Science Foundation of China (No. 50539080)Ministry of Education Research Fund for the doctoral program of China (No. 20133718110004)+2 种基金the Natural Science Key Foundation of Shandong Province of China (No. ZR2011EEZ002)the Technology Project Development Plan of Qingdao Economic and Technological Development Zone of China (No. 2013-1-62)SDUST Research Fund of China (No. 2012KYTD101)
文摘The method of singular coefficient of water inrush to achieve safety mining has limitation and one sidedness. Aiming at the problem above, large amounts of data about water inrush were collected. Then the data, including the maximum water inrush, water inrush coefficient and water abundance in aquifers of working face, were processed by the statistical analysis. The analysis results indicate that both water inrush coefficient and water abundance in aquifers should be taken into consideration when evaluating the danger of water inrush from coal seam floor. The prediction model of safe-mining evaluation grade was built by using the support vector machine, and the result shows that this model has high classification accuracy. A feasible classification system of water-inrush safety evaluation can be got by using the data visualization method which makes the implicit support vector machine models explicit.
文摘In this paper, several approaches for calculation of the effective tensor coefficient for domains with inclusions have been proposed. The limits of the approaches using are found. The series of numerical experiments are made on the different frequencies, for different inclusions location and boundary conditions for the contrast properties of the matrix and inclusion materials.
文摘In this study, a reliability index vector formula is proposed for series system with two failure modes in term of the concept of reliability index vector and equivalent failure modes. Firstly, the reliability index vector is introduced to determine the correlation coefficient between two failure modes, and then, the reliability index vector of a series system can be obtained. Several numerical cases and an analysis on offshore platform are performed, and the results show that this scheme provided here has better computational accuracy, and its calculation process is simpler for the series systems reliability calculations compared with the other methods. Also this scheme is more convenient for the engineering applications.
文摘We study the quantum theory of the mass-less vector fields on the Rindler space. We evaluate the Bogoliubov coefficients by means of a new technique based upon the use of light-front coordinates and Mellin transform. We briefly comment about the ensuing Unruh effect and its consequences.
文摘This research paper presents a numerical study on the flow characteristics and performance of a baffled shock two-dimensional vector nozzle. The baffled shock vector nozzle is a type of fluid thrust vectoring nozzle that uses a secondary injection to deflect the primary flow and generate a vector angle. The fluid thrust vectoring technology is regarded as a key technology for the development of very low detectable vehicles because of its advantages, such as fast response, lightweight, and good stealth performance. The main objectives of this study are to investigate the effects of various parameters such as slot interval distance, slot width, injection angle, nozzle pressure ratio, secondary flow pressure ratio, and outflow Mach number on the deflection angle, thrust coefficient, thrust efficiency, and secondary flow ratio of the nozzle. The numerical simulations are carried out using the k-epsilon turbulence model, which is validated by comparing it with experimental data. The results indicate that optimizing the slot interval distance and width, increasing the injection angle, adjusting the nozzle pressure ratio and secondary flow pressure ratio, and controlling the outflow Mach number can enhance the nozzle performance. The results also reveal the complex flow phenomena inside the nozzle, such as shock wave interactions, flow separation and reattachment, and boundary layer effects. The study provides a comprehensive understanding of the flow characteristics and performance of a baffled shock two-dimensional vector nozzle and offers some guidance for its design and optimization.
