We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for gen...We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for general cases of off-axis scenarios where the sampling intervals and numbers of the input and observation planes are unequal.Additionally,it allows for arbitrary adjustment of the sampling interval of the impulse response function,facilitating a manual trade-off between computational load and accuracy.The er-rors associated with this method,which is equivalent to interpolation,primarily arise from the discontinuities of the sampling matrix of the impulse response function on its boundaries of periodic extension.To address this issue,we propose the concept of the padding function and its construction method,and evaluate its ef-fectiveness in enhancing computational accuracy.The feasibility of the proposed method is verified by nu-merical simulation and compared with the direct integration DI-method in a simplified scenario.It shows that the proposed method has good computational accuracy for the general case where the sampling interval of the input and observation plane is not equal under non-near-field diffraction,and when the diffraction distance is large,although the computational accuracy of the proposed method cannot exceed that of the DI-method,the computational amount can be significantly reduced with almost no effect on the computational accuracy.This method provides a general numerical calculation scheme of diffraction in the non-near field case for areas such as computational holography.展开更多
The pantograph cavity coupling system(PCCS)of high-speed trains,as a representative region for aerodynamic noise generation,merits further investigation into its scale effects.In this paper,the large-eddy simulation(L...The pantograph cavity coupling system(PCCS)of high-speed trains,as a representative region for aerodynamic noise generation,merits further investigation into its scale effects.In this paper,the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)integral equation are used to calculate and analyze the sound energy intensity distribution pattern and spectral characteristics of the PCCS at different scales(1/1,1/2,1/4,1/8,1/16,1/25,1/50).The research shows that as the scaled model decreases,the relative area of the pantograph submerged by the vehicle boundary layer increases,and its inflow velocity decreases,thereby reducing the overall radiated sound pressure level in this area.For the segments 1/1-1/2 and 1/4-1/16,the dominant scale of sound generation is typical pure tone noise,with distinct similar features in the spectral discrete scales.For the segments 1/25-1/50,the turbulent fluctuation characteristics of the vehicle boundary layer mask the peak features,and the spectrum is dominated by broadband characteristics.Combining the PCCS sound source energy scale correction model and the dimensionless spectrum correction function,a scale correction model for the sound power spectrum of the sound source is obtained,so that the noise results of the reduced-scale model can be corresponded to the full-scale model.This work advances the comprehension of high-speed train aerodynamic noise generation mechanisms and offers critical references for developing precision noise control technologies.展开更多
目的探讨由美国国家医学中心和贝克曼研究所研制的癌症患者照顾者生活质量量表(Quality of LifeFamily Version,QOLScale-FAMILY)用于中国喉癌患者照顾者生活质量测量的可能性,为喉癌患者照顾者生活质量的评定提供一个量化工具。方法通...目的探讨由美国国家医学中心和贝克曼研究所研制的癌症患者照顾者生活质量量表(Quality of LifeFamily Version,QOLScale-FAMILY)用于中国喉癌患者照顾者生活质量测量的可能性,为喉癌患者照顾者生活质量的评定提供一个量化工具。方法通过对QOLScale-FAMILY量表的翻译、回译、文化调试制定出中文版的QOL Scale-FAMILY量表,并采用信访、电话访谈、面对面问卷访谈的方法,对100例喉癌患者照顾者(主要是患者配偶和子女)的生活质量进行测定,考核QOL Scale-FAMILY的可行性以及信度与效度。结果中文版的QOL Scale-FAMILY具有良好的内部一致性,总量表的Cronbach′sα系数为0.794,除了精神健康维度α=0.649外,其他3个维度满足群组比较的要求;重测信度γ=0.841。因子分析产生的4个公共因子与理论结构基本一致,结构效度的累积方差贡献率为60.2%。结论QOLScale-FAMILY中文版具有较好的信度和效度,对部分条目进行调整后,可以应用于喉癌患者照顾者生活质量的测定。展开更多
On the basis of scale invariant feature transform（SIFT） descriptors,a novel kind of local invariants based on SIFT sequence scale（SIFT-SS） is proposed and applied to target classification.First of all,the merits o...On the basis of scale invariant feature transform（SIFT） descriptors,a novel kind of local invariants based on SIFT sequence scale（SIFT-SS） is proposed and applied to target classification.First of all,the merits of using an SIFT algorithm for target classification are discussed.Secondly,the scales of SIFT descriptors are sorted by descending as SIFT-SS,which is sent to a support vector machine（SVM） with radial based function（RBF） kernel in order to train SVM classifier,which will be used for achieving target classification.Experimental results indicate that the SIFT-SS algorithm is efficient for target classification and can obtain a higher recognition rate than affine moment invariants（AMI） and multi-scale auto-convolution（MSA） in some complex situations,such as the situation with the existence of noises and occlusions.Moreover,the computational time of SIFT-SS is shorter than MSA and longer than AMI.展开更多
Stable local feature detection is a fundamental component of many stereo vision problems such as 3-D reconstruction, object localization, and object tracking. A robust method for extracting scale-invariant feature poi...Stable local feature detection is a fundamental component of many stereo vision problems such as 3-D reconstruction, object localization, and object tracking. A robust method for extracting scale-invariant feature points is presented. First, the Harris corners in three-level pyramid are extracted. Then, the points detected at the highest level of the pyramid are correctly propagated to the lower level by pyramid based scale invariant （PBSI） method. The corners detected repeatedly in different levels are chosen as final feature points. Finally, the characteristic scale is obtained based on maximum entropy method. The experimental results show that the algorithm has low computation cost, strong antinoise capability, and excellent performance in the presence of significant scale changes.展开更多
In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of produc...In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.展开更多
Contraposing the need of the robust digital watermark for the copyright protection field, a new digital watermarking algorithm in the non-subsampled contourlet transform （NSCT） domain is proposed. The largest energy...Contraposing the need of the robust digital watermark for the copyright protection field, a new digital watermarking algorithm in the non-subsampled contourlet transform （NSCT） domain is proposed. The largest energy sub-band after NSCT is selected to embed watermark. The watermark is embedded into scaleinvariant feature transform （SIFT） regions. During embedding, the initial region is divided into some cirque sub-regions with the same area, and each watermark bit is embedded into one sub-region. Extensive simulation results and comparisons show that the algorithm gets a good trade-off of invisibility, robustness and capacity, thus obtaining good quality of the image while being able to effectively resist common image processing, and geometric and combo attacks, and normalized similarity is almost all reached.展开更多
It is obvious that the change trend of our government expenditure scale declined constantly .The expenditure proportion of science, education, culture and hygiene increased fast, reflected the situation that the finan...It is obvious that the change trend of our government expenditure scale declined constantly .The expenditure proportion of science, education, culture and hygiene increased fast, reflected the situation that the finance of our country was transformed into “public finance” from “building type finance” gradually.The expenditure proportion of the local is higher than central authorities. This is disadvantageous for our country’s economy development and society stability.展开更多
文摘We propose a novel fast numerical calculation method for the Rayleigh-Sommerfeld diffraction integral,which is developed based on the existing scaled convolution method.This approach enables fast cal-culations for general cases of off-axis scenarios where the sampling intervals and numbers of the input and observation planes are unequal.Additionally,it allows for arbitrary adjustment of the sampling interval of the impulse response function,facilitating a manual trade-off between computational load and accuracy.The er-rors associated with this method,which is equivalent to interpolation,primarily arise from the discontinuities of the sampling matrix of the impulse response function on its boundaries of periodic extension.To address this issue,we propose the concept of the padding function and its construction method,and evaluate its ef-fectiveness in enhancing computational accuracy.The feasibility of the proposed method is verified by nu-merical simulation and compared with the direct integration DI-method in a simplified scenario.It shows that the proposed method has good computational accuracy for the general case where the sampling interval of the input and observation plane is not equal under non-near-field diffraction,and when the diffraction distance is large,although the computational accuracy of the proposed method cannot exceed that of the DI-method,the computational amount can be significantly reduced with almost no effect on the computational accuracy.This method provides a general numerical calculation scheme of diffraction in the non-near field case for areas such as computational holography.
基金Project(52272363)supported by the National Natural Science Foundation of ChinaProject(2025JJ50308)supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(K-BBY1)supported by the Smart Railway Technology and Application,ChinaProject(1-W32Z)supported by the Postdoc Matching Fund Scheme,ChinaProject(ANCL20200302)supported by the Key Laboratory of Aerodynamic Noise Control,China。
文摘The pantograph cavity coupling system(PCCS)of high-speed trains,as a representative region for aerodynamic noise generation,merits further investigation into its scale effects.In this paper,the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)integral equation are used to calculate and analyze the sound energy intensity distribution pattern and spectral characteristics of the PCCS at different scales(1/1,1/2,1/4,1/8,1/16,1/25,1/50).The research shows that as the scaled model decreases,the relative area of the pantograph submerged by the vehicle boundary layer increases,and its inflow velocity decreases,thereby reducing the overall radiated sound pressure level in this area.For the segments 1/1-1/2 and 1/4-1/16,the dominant scale of sound generation is typical pure tone noise,with distinct similar features in the spectral discrete scales.For the segments 1/25-1/50,the turbulent fluctuation characteristics of the vehicle boundary layer mask the peak features,and the spectrum is dominated by broadband characteristics.Combining the PCCS sound source energy scale correction model and the dimensionless spectrum correction function,a scale correction model for the sound power spectrum of the sound source is obtained,so that the noise results of the reduced-scale model can be corresponded to the full-scale model.This work advances the comprehension of high-speed train aerodynamic noise generation mechanisms and offers critical references for developing precision noise control technologies.
基金supported by the National High Technology Research and Development Program (863 Program) (2010AA7080302)
文摘On the basis of scale invariant feature transform（SIFT） descriptors,a novel kind of local invariants based on SIFT sequence scale（SIFT-SS） is proposed and applied to target classification.First of all,the merits of using an SIFT algorithm for target classification are discussed.Secondly,the scales of SIFT descriptors are sorted by descending as SIFT-SS,which is sent to a support vector machine（SVM） with radial based function（RBF） kernel in order to train SVM classifier,which will be used for achieving target classification.Experimental results indicate that the SIFT-SS algorithm is efficient for target classification and can obtain a higher recognition rate than affine moment invariants（AMI） and multi-scale auto-convolution（MSA） in some complex situations,such as the situation with the existence of noises and occlusions.Moreover,the computational time of SIFT-SS is shorter than MSA and longer than AMI.
基金supported by the Development Program of China and the National Science Foundation Project (60475024)National High Technology Research (2006AA09Z203)
文摘Stable local feature detection is a fundamental component of many stereo vision problems such as 3-D reconstruction, object localization, and object tracking. A robust method for extracting scale-invariant feature points is presented. First, the Harris corners in three-level pyramid are extracted. Then, the points detected at the highest level of the pyramid are correctly propagated to the lower level by pyramid based scale invariant （PBSI） method. The corners detected repeatedly in different levels are chosen as final feature points. Finally, the characteristic scale is obtained based on maximum entropy method. The experimental results show that the algorithm has low computation cost, strong antinoise capability, and excellent performance in the presence of significant scale changes.
基金Project(2012BAK09B02-05) supported by the National "Twelfth Five-year" Science & Technology Support Plan of China
文摘In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.
基金supported by the National Natural Science Foundation of China(61379010)the Natural Science Basic Research Plan in Shaanxi Province of China(2015JM6293)
文摘Contraposing the need of the robust digital watermark for the copyright protection field, a new digital watermarking algorithm in the non-subsampled contourlet transform （NSCT） domain is proposed. The largest energy sub-band after NSCT is selected to embed watermark. The watermark is embedded into scaleinvariant feature transform （SIFT） regions. During embedding, the initial region is divided into some cirque sub-regions with the same area, and each watermark bit is embedded into one sub-region. Extensive simulation results and comparisons show that the algorithm gets a good trade-off of invisibility, robustness and capacity, thus obtaining good quality of the image while being able to effectively resist common image processing, and geometric and combo attacks, and normalized similarity is almost all reached.
文摘It is obvious that the change trend of our government expenditure scale declined constantly .The expenditure proportion of science, education, culture and hygiene increased fast, reflected the situation that the finance of our country was transformed into “public finance” from “building type finance” gradually.The expenditure proportion of the local is higher than central authorities. This is disadvantageous for our country’s economy development and society stability.
