In this study,vector quantization and hidden Markov models were used to achieve speech command recognition.Pre-emphasis,a hamming window,and Mel-frequency cepstral coefficients were first adopted to obtain feature val...In this study,vector quantization and hidden Markov models were used to achieve speech command recognition.Pre-emphasis,a hamming window,and Mel-frequency cepstral coefficients were first adopted to obtain feature values.Subsequently,vector quantization and HMMs(hidden Markov models)were employed to achieve speech command recognition.The recorded speech length was three Chinese characters,which were used to test the method.Five phrases pronounced mixing various human voices were recorded and used to test the models.The recorded phrases were then used for speech command recognition to demonstrate whether the experiment results were satisfactory.展开更多
In this paper,the large eddy simulation(LES)method is used to calculate Reynolds numbers the range in the range of 3000–30000(based on the diameter of the hemisphere D),and then the statistical analysis method is use...In this paper,the large eddy simulation(LES)method is used to calculate Reynolds numbers the range in the range of 3000–30000(based on the diameter of the hemisphere D),and then the statistical analysis method is used to study the influence of Re on the characteristics of the flow field around the rough hemisphere and the evolution law of the tail vortex.The effect of the Reynolds number on the structure of the rough hemisphere flow field and the evolution of vortex structure is studied by vorticity distribution,POD method,and correlation analysis.It can be observed that with the increase of Reynolds number,the shear in the recirculating region of the rough hemisphere is enhanced,the large-scale structure is reduced,the small-scale structure is increased,and the angle between the hairpin vortex and the wall is reduced.λ_(ci)vortex identification and the Q-criterion are used to capture the evolution of a periodic vortex structure.Q-criterion gives the three-dimensional vortex structure behind the hemispherical flow.It is found that the horseshoe vortex and arch vortex generated by the incoming flow after passing through the hemisphere will interact with the wall surface to form a hairpin vortex,and the hairpin vortex structure will continue to evolve downstream to form a new vortex structure.展开更多
The activation and deactivation of the chain-transfer agent were achieved by oxygen initiation and regulation with triethylborane under ambient temperature and atmosphere.The autoxidation of triethylborane overcame th...The activation and deactivation of the chain-transfer agent were achieved by oxygen initiation and regulation with triethylborane under ambient temperature and atmosphere.The autoxidation of triethylborane overcame the oxygen inhilbition and produced initiating radicals that selectively activate the chain-transfer agent for the chain growth or deactivate the active chain-end of polymer in controlled radical polymerization.Both activation and deactivation were highly efficient with broad scope for various polymers with different chain-transfer agents in both organic and aqueous systems.Oxygen molecule was particularly used as an external regulator to initiate and achieve the temporal control of both activation and deactivation by simply feeding the air.展开更多
In this paper, Liutex similarity is extended and revised in channel turbulence. Liutex similarity is free from viscous dissipation, relaxing the very high Reynolds number assumption of K41. Liutex similarity hypothesi...In this paper, Liutex similarity is extended and revised in channel turbulence. Liutex similarity is free from viscous dissipation, relaxing the very high Reynolds number assumption of K41. Liutex similarity hypothesis in 2-D channel turbulence is first proposed and estimated, which denotes that the statistical properties of Liutex field are uniquely and universally determined by the scale l, Liutex vortex number density n(A) with each area A and mean dissipation rate of square of Liutex magnitude ηL. The Liutex spectrum is EL (k) ∼ C[n(A)1/2ηL]1/3k−5/3 in the inertial range where energy spectrum exhibits double cascades. The scaling behaviors of Liutex spectrum in 2-D are independent of Reynolds number. Liutex structure functions are defined as Liutexp (l) ≡ 〈[δR∥(l)]p〉 which are in dependent of scales. It is found that Liutexp (l) ∼ C′(ηL)p/3l0 by dimensional analysis.展开更多
基金This research work was supported by the Ministry of Science and Technology of the Republic of China under contract MOST 108-2221-E-390-018.
文摘In this study,vector quantization and hidden Markov models were used to achieve speech command recognition.Pre-emphasis,a hamming window,and Mel-frequency cepstral coefficients were first adopted to obtain feature values.Subsequently,vector quantization and HMMs(hidden Markov models)were employed to achieve speech command recognition.The recorded speech length was three Chinese characters,which were used to test the method.Five phrases pronounced mixing various human voices were recorded and used to test the models.The recorded phrases were then used for speech command recognition to demonstrate whether the experiment results were satisfactory.
基金supported by the National Natural Science Foundation of China(Grant No.91952102).
文摘In this paper,the large eddy simulation(LES)method is used to calculate Reynolds numbers the range in the range of 3000–30000(based on the diameter of the hemisphere D),and then the statistical analysis method is used to study the influence of Re on the characteristics of the flow field around the rough hemisphere and the evolution law of the tail vortex.The effect of the Reynolds number on the structure of the rough hemisphere flow field and the evolution of vortex structure is studied by vorticity distribution,POD method,and correlation analysis.It can be observed that with the increase of Reynolds number,the shear in the recirculating region of the rough hemisphere is enhanced,the large-scale structure is reduced,the small-scale structure is increased,and the angle between the hairpin vortex and the wall is reduced.λ_(ci)vortex identification and the Q-criterion are used to capture the evolution of a periodic vortex structure.Q-criterion gives the three-dimensional vortex structure behind the hemispherical flow.It is found that the horseshoe vortex and arch vortex generated by the incoming flow after passing through the hemisphere will interact with the wall surface to form a hairpin vortex,and the hairpin vortex structure will continue to evolve downstream to form a new vortex structure.
基金the National Natural Science Foundation of China(Nos.21704017,21871056,and 91956122).
文摘The activation and deactivation of the chain-transfer agent were achieved by oxygen initiation and regulation with triethylborane under ambient temperature and atmosphere.The autoxidation of triethylborane overcame the oxygen inhilbition and produced initiating radicals that selectively activate the chain-transfer agent for the chain growth or deactivate the active chain-end of polymer in controlled radical polymerization.Both activation and deactivation were highly efficient with broad scope for various polymers with different chain-transfer agents in both organic and aqueous systems.Oxygen molecule was particularly used as an external regulator to initiate and achieve the temporal control of both activation and deactivation by simply feeding the air.
基金The research is sponsored by Shuguang Program supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission in China(Grant No.18SG53)the Double Innovation Program of Jiangsu Province,China,2018+1 种基金Projects supported by the National Natural Science Foundation of China(Grant No.91952102,12032016)the National Key Research and Development Program of China(Grant No.2018YFB0204404).
文摘In this paper, Liutex similarity is extended and revised in channel turbulence. Liutex similarity is free from viscous dissipation, relaxing the very high Reynolds number assumption of K41. Liutex similarity hypothesis in 2-D channel turbulence is first proposed and estimated, which denotes that the statistical properties of Liutex field are uniquely and universally determined by the scale l, Liutex vortex number density n(A) with each area A and mean dissipation rate of square of Liutex magnitude ηL. The Liutex spectrum is EL (k) ∼ C[n(A)1/2ηL]1/3k−5/3 in the inertial range where energy spectrum exhibits double cascades. The scaling behaviors of Liutex spectrum in 2-D are independent of Reynolds number. Liutex structure functions are defined as Liutexp (l) ≡ 〈[δR∥(l)]p〉 which are in dependent of scales. It is found that Liutexp (l) ∼ C′(ηL)p/3l0 by dimensional analysis.
