This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour p...This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour process takes place in two stages: the initial rapid scour and the subsequent gradual scour development stage. An empirical formula for calculating the equilibrium scour depth(the maximum scour depth) is developed by using the regression method. This formula together with the maximum entropy theory can be applied to establish a formula to predict the scour process for given water depth, diameter of pipeline and flow velocity. Good agreement between the predicted and measured scour depth is obtained.展开更多
An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration ...An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration of a fully collapsed ring is considered as a real dumbbell shape with a line touch between two 'bells', instead of the dumbbell shape with a point touch of two diametrically opposite points. Calculations are performed assuming that the dominant effect on the plastic energy dissipation has the circumferential bending mode. For the linear strain-hardening materials it is found that theoretical predictions based on the above model for both propagation pressure and initiation nressure are in good agreement with experimental results of Kyriakides et al.展开更多
This paper proposes a digital background calibration algorithm to correct linearity errors in a pipelined analog-to-digital converter（ADC）.The algorithm does not modify the analog circuit of pipelined stages and cal...This paper proposes a digital background calibration algorithm to correct linearity errors in a pipelined analog-to-digital converter（ADC）.The algorithm does not modify the analog circuit of pipelined stages and calibrates the raw conversion output by using a backend digital logic.Based on the analysis of the output codes,the calibration logic estimates the bit weight of each stage and corrects the outputs.An experimental 14-bit pipelined ADC is fabricated to verify the algorithm.The results show that INL errors drop from 20 LSB to 1.7 LSB,DNL errors drop from 2 LSB to 0.4 LSB,SNDR grows from 57 to 65.7 dB and THD drops from -58 to -81 dB.The linearity of the pipelined ADC is improved significantly.展开更多
基金financially supported by the National Nature Science Foundation of China (Grant No. 51279189)
文摘This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour process takes place in two stages: the initial rapid scour and the subsequent gradual scour development stage. An empirical formula for calculating the equilibrium scour depth(the maximum scour depth) is developed by using the regression method. This formula together with the maximum entropy theory can be applied to establish a formula to predict the scour process for given water depth, diameter of pipeline and flow velocity. Good agreement between the predicted and measured scour depth is obtained.
基金Project supported by National Natural Science Foundation
文摘An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration of a fully collapsed ring is considered as a real dumbbell shape with a line touch between two 'bells', instead of the dumbbell shape with a point touch of two diametrically opposite points. Calculations are performed assuming that the dominant effect on the plastic energy dissipation has the circumferential bending mode. For the linear strain-hardening materials it is found that theoretical predictions based on the above model for both propagation pressure and initiation nressure are in good agreement with experimental results of Kyriakides et al.
文摘This paper proposes a digital background calibration algorithm to correct linearity errors in a pipelined analog-to-digital converter（ADC）.The algorithm does not modify the analog circuit of pipelined stages and calibrates the raw conversion output by using a backend digital logic.Based on the analysis of the output codes,the calibration logic estimates the bit weight of each stage and corrects the outputs.An experimental 14-bit pipelined ADC is fabricated to verify the algorithm.The results show that INL errors drop from 20 LSB to 1.7 LSB,DNL errors drop from 2 LSB to 0.4 LSB,SNDR grows from 57 to 65.7 dB and THD drops from -58 to -81 dB.The linearity of the pipelined ADC is improved significantly.
