An initial prediction of the particulate mode of flow in pneumatic conveying systems is beneficial as this knowledge can provide clearer direction to the pneumatic conveying design process. There are three general cat...An initial prediction of the particulate mode of flow in pneumatic conveying systems is beneficial as this knowledge can provide clearer direction to the pneumatic conveying design process. There are three general categories of modes of flow, two dense flows： fluidised dense phase and plug flow, and dilute phase oniy. Detailed in this paper is a review of the commonly used and available techniques for predicting mode of flow. Two types of predictive charts were defined： basic particle parameter based （e.g. particle size and density） and air-particle parameter based （e.g. permeability and de-aeration）. The basic particle techniques were found to have strong and weak areas of predictive ability, on the basis of a comparison with data from materials with known mode of flow capability. It was found that there was only slight improvement in predictive ability when the particle density was replaced by loose-poured bulk density in the basic parameter techniques. The air-particle-parameter-based techniques also showed well-defined regions for mode of flow prediction though the data set used was smaller than that for the basic techniques. Also, it was found to be difficult to utilise de-aeration values from different researchers and subsequently, an air-particle-based technique was developed which does not require any de-aeration parameter in its assessment.展开更多
The objective of this study was to relate experimental pressure fluctuation behavior to the transition in mode of flow observed in fluidized dense phase pneumatic conveying of fly ash.Shannon entropy and wavelet analy...The objective of this study was to relate experimental pressure fluctuation behavior to the transition in mode of flow observed in fluidized dense phase pneumatic conveying of fly ash.Shannon entropy and wavelet analysis were utilized to extract features of the flow regimes.Daubechies db4 wavelet analysis of pulsating air pressure revealed that the flow mechanism of fly ash in a fluidized dense phase possessed non-steady characteristics associated with gradual aeration of dunes along the direction of flow.Variations of Shannon entropy values along the length of the pipeline were assessed to determine the location at which the flow converted from dense to dilute phase mode.The effects of conveying parameters and specific power consumption on Shannon entropy and variations of the local power consumption coefficient are discussed.展开更多
A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) la...A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.展开更多
文摘An initial prediction of the particulate mode of flow in pneumatic conveying systems is beneficial as this knowledge can provide clearer direction to the pneumatic conveying design process. There are three general categories of modes of flow, two dense flows： fluidised dense phase and plug flow, and dilute phase oniy. Detailed in this paper is a review of the commonly used and available techniques for predicting mode of flow. Two types of predictive charts were defined： basic particle parameter based （e.g. particle size and density） and air-particle parameter based （e.g. permeability and de-aeration）. The basic particle techniques were found to have strong and weak areas of predictive ability, on the basis of a comparison with data from materials with known mode of flow capability. It was found that there was only slight improvement in predictive ability when the particle density was replaced by loose-poured bulk density in the basic parameter techniques. The air-particle-parameter-based techniques also showed well-defined regions for mode of flow prediction though the data set used was smaller than that for the basic techniques. Also, it was found to be difficult to utilise de-aeration values from different researchers and subsequently, an air-particle-based technique was developed which does not require any de-aeration parameter in its assessment.
文摘The objective of this study was to relate experimental pressure fluctuation behavior to the transition in mode of flow observed in fluidized dense phase pneumatic conveying of fly ash.Shannon entropy and wavelet analysis were utilized to extract features of the flow regimes.Daubechies db4 wavelet analysis of pulsating air pressure revealed that the flow mechanism of fly ash in a fluidized dense phase possessed non-steady characteristics associated with gradual aeration of dunes along the direction of flow.Variations of Shannon entropy values along the length of the pipeline were assessed to determine the location at which the flow converted from dense to dilute phase mode.The effects of conveying parameters and specific power consumption on Shannon entropy and variations of the local power consumption coefficient are discussed.
基金supported by the National Natural Science Foundation of China(No.61475015)
文摘A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.
