During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure ...During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.展开更多
We examine the relation between managerial ability and management forecast accuracy. We base our analysis on S＆P 500 Composite Index constituents for the period of 2006-2012. Data were collected from Thomson Reuteurs...We examine the relation between managerial ability and management forecast accuracy. We base our analysis on S＆P 500 Composite Index constituents for the period of 2006-2012. Data were collected from Thomson Reuteurs, Compustat and Demerjian, Lev, and McVay （2012）. We find that forecast accuracy is positively associated with managerial ability in the case of sales forecasts. Specifically, more able managers are associated with lower magnitude＇s forecast errors in the case of sales forecasts. Additional analysis finds that managerial ability is immaterial to EPS figures＇ forecast accuracy, i.e., EPS forecasts appear not to be affected by manager＇s superiority. Regarding sales forecasts, the results are consistent with the assertion that managers impact the quality of the delivered management forecasts. Regarding EPS forecasts, the results are in alignment with Demerjian, Lev, Lewis, and McVay （2013） who highlighted that managerial ability is an ability score related to the entire management team.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09Z302)
文摘During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.
文摘We examine the relation between managerial ability and management forecast accuracy. We base our analysis on S＆P 500 Composite Index constituents for the period of 2006-2012. Data were collected from Thomson Reuteurs, Compustat and Demerjian, Lev, and McVay （2012）. We find that forecast accuracy is positively associated with managerial ability in the case of sales forecasts. Specifically, more able managers are associated with lower magnitude＇s forecast errors in the case of sales forecasts. Additional analysis finds that managerial ability is immaterial to EPS figures＇ forecast accuracy, i.e., EPS forecasts appear not to be affected by manager＇s superiority. Regarding sales forecasts, the results are consistent with the assertion that managers impact the quality of the delivered management forecasts. Regarding EPS forecasts, the results are in alignment with Demerjian, Lev, Lewis, and McVay （2013） who highlighted that managerial ability is an ability score related to the entire management team.
