A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed usin...A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed using concentration modulation(CM)spectroscopy.The intensities and orientations of the absorption peaks change with the demodulation phase,but the direction of one absorption peak of H2O is always opposite to the other peaks.The different spectral orientations of OH and H2O reflect the increase or the decrease of the number of particles in the energy levels.If more transient species can be detected in the discharge process,the dynamics of excitation,ionization,and decomposition of H2O can be better studied.This study shows that the demodulation phase relationship of CM spectrum can be used to study the population change of molecular energy levels.展开更多
Internal model control （IMC） yields very good performance for set point tracking, but gives sluggish response for disturbance rejection problem. A two-degree-of-freedom IMC （2DOF-IMC） has been developed to overcom...Internal model control （IMC） yields very good performance for set point tracking, but gives sluggish response for disturbance rejection problem. A two-degree-of-freedom IMC （2DOF-IMC） has been developed to overcome the weakness. However, the setting of parameter becomes a complicated matter if there is an uncertainty model. The present study proposes a new tuning method for the controller. The proposed tuning method consists of three steps. Firstly, the worst case of the model uncertainty is determined. Secondly, the parameter of set point con- troller using maximum peak （Mp） criteria is specified, and finally, the parameter of the disturbance rejection con- troller using gain margin （GM） criteria is obtained. The proposed method is denoted as Mp-GM tuning method. The effectiveness of Mp-GM tuning method has evaluated and compared with IMC-controller tuning program （IMCTUNE） as bench mark. The evaluation and comparison have been done through the simulation on a number of first order plus dead time （FOPDT） and higher order processes. The FOPDT process tested includes processes with controllability ratio in the range 0.7 to 2.5. The higher processes include second order with underdarnped and third order with nonminimum phase processes. Although the two of higher order processes are considered as difficult processes, the proposed Mp-GM tuning method are able to obtain the good controller parameter even under process uncertainties.展开更多
This paper explains the root cause of China＇s trade surplus and argues that it is rooted in structural factors. China＇s dual economic structure and the relatively slow growth in wages due to the abundant supply of l...This paper explains the root cause of China＇s trade surplus and argues that it is rooted in structural factors. China＇s dual economic structure and the relatively slow growth in wages due to the abundant supply of labor have led to a large supply glut between China＇s domestic demand and output, which has been balanced by export. This is a structural problem that cannot be solved by currency appreciation or the readjustment of capital account deficits. A potentially viable option is to adjust the current account by developing a new opening-up system featuring more freedom and compliance.展开更多
Lately, it is required that the bandwidth of PWM （pulse width modulation） power amplifier is extended. For example, it is in application of the testing power supply of a low frequency immunity examination, or a clas...Lately, it is required that the bandwidth of PWM （pulse width modulation） power amplifier is extended. For example, it is in application of the testing power supply of a low frequency immunity examination, or a class-D amplifier. In this paper, the authors show that the bandwidth of PWM power amplifier can be controller. This controller is implemented on a DSP （digital can be made wider with this controller. extended by using an approximate 2DOF （2-degree-of-freedom） digital signal processor）. It is demonstrated from experiments that the bandwidth展开更多
Direct observation is arguably the preferred way to investigate the interactions between two molecular complexes. With the development of high speed atomic force microscopy （AFM）, it is becoming possible to observe ...Direct observation is arguably the preferred way to investigate the interactions between two molecular complexes. With the development of high speed atomic force microscopy （AFM）, it is becoming possible to observe directly DNA-protein interactions with relevant spatial and temporal resolutions. These interactions are of central importance to biology, bionanotechnology, and functional biologically inspired materials. As in all microscopy studies, sample preparation plays a central role in AFM observation and minimal perturbation of the sample is desired. Here, we demonstrate the ability to tune the interactions between DNA molecules and the surface to create an association strong enough to enable high-resolution AFM imaging while also providing sufficient translational freedom to allow the relevant protein-DNA interactions to take place. Furthermore, we describe a quantitative method for measuring DNA mobility, while also determining the individual forces contributing to DNA movement. We found that for a weak surface association, a significant contribution to the movement arises from the interaction of the AFM tip with the DNA. In combination, these methods enable the tuning of the surface translational freedom of DNA molecules to allow the direct study of a wide range of nucleo-protein interactions by high speed atomic force microscopy.展开更多
基金the National Natural Science Foundation of China(No.61625501,No.61427816)the Open Fund of the State Key Laboratory of High Field Laser Physics(SIOM)the Open Fund of the State Key Laboratory of Precision Spectroscopy。
文摘A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed using concentration modulation(CM)spectroscopy.The intensities and orientations of the absorption peaks change with the demodulation phase,but the direction of one absorption peak of H2O is always opposite to the other peaks.The different spectral orientations of OH and H2O reflect the increase or the decrease of the number of particles in the energy levels.If more transient species can be detected in the discharge process,the dynamics of excitation,ionization,and decomposition of H2O can be better studied.This study shows that the demodulation phase relationship of CM spectrum can be used to study the population change of molecular energy levels.
基金Supported by Postgraduate Fellowship of UMP,Fundamental Research Grant Scheme of Malaysia(GRS070120)Joint Research Grant between Universiti Malaysia Pahang (UMP) and Institut Teknologi Sepuluh Nopember (ITS) Surabaya
文摘Internal model control （IMC） yields very good performance for set point tracking, but gives sluggish response for disturbance rejection problem. A two-degree-of-freedom IMC （2DOF-IMC） has been developed to overcome the weakness. However, the setting of parameter becomes a complicated matter if there is an uncertainty model. The present study proposes a new tuning method for the controller. The proposed tuning method consists of three steps. Firstly, the worst case of the model uncertainty is determined. Secondly, the parameter of set point con- troller using maximum peak （Mp） criteria is specified, and finally, the parameter of the disturbance rejection con- troller using gain margin （GM） criteria is obtained. The proposed method is denoted as Mp-GM tuning method. The effectiveness of Mp-GM tuning method has evaluated and compared with IMC-controller tuning program （IMCTUNE） as bench mark. The evaluation and comparison have been done through the simulation on a number of first order plus dead time （FOPDT） and higher order processes. The FOPDT process tested includes processes with controllability ratio in the range 0.7 to 2.5. The higher processes include second order with underdarnped and third order with nonminimum phase processes. Although the two of higher order processes are considered as difficult processes, the proposed Mp-GM tuning method are able to obtain the good controller parameter even under process uncertainties.
文摘This paper explains the root cause of China＇s trade surplus and argues that it is rooted in structural factors. China＇s dual economic structure and the relatively slow growth in wages due to the abundant supply of labor have led to a large supply glut between China＇s domestic demand and output, which has been balanced by export. This is a structural problem that cannot be solved by currency appreciation or the readjustment of capital account deficits. A potentially viable option is to adjust the current account by developing a new opening-up system featuring more freedom and compliance.
文摘Lately, it is required that the bandwidth of PWM （pulse width modulation） power amplifier is extended. For example, it is in application of the testing power supply of a low frequency immunity examination, or a class-D amplifier. In this paper, the authors show that the bandwidth of PWM power amplifier can be controller. This controller is implemented on a DSP （digital can be made wider with this controller. extended by using an approximate 2DOF （2-degree-of-freedom） digital signal processor）. It is demonstrated from experiments that the bandwidth
文摘Direct observation is arguably the preferred way to investigate the interactions between two molecular complexes. With the development of high speed atomic force microscopy （AFM）, it is becoming possible to observe directly DNA-protein interactions with relevant spatial and temporal resolutions. These interactions are of central importance to biology, bionanotechnology, and functional biologically inspired materials. As in all microscopy studies, sample preparation plays a central role in AFM observation and minimal perturbation of the sample is desired. Here, we demonstrate the ability to tune the interactions between DNA molecules and the surface to create an association strong enough to enable high-resolution AFM imaging while also providing sufficient translational freedom to allow the relevant protein-DNA interactions to take place. Furthermore, we describe a quantitative method for measuring DNA mobility, while also determining the individual forces contributing to DNA movement. We found that for a weak surface association, a significant contribution to the movement arises from the interaction of the AFM tip with the DNA. In combination, these methods enable the tuning of the surface translational freedom of DNA molecules to allow the direct study of a wide range of nucleo-protein interactions by high speed atomic force microscopy.
