Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing...Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.展开更多
AIM: To determine if surgical biliary bypass would provide improved quality of residual life and safe palliation in elderly patients with unresectable pancreatic head cancer. METHODS: Nineteen patients, 65 years of ag...AIM: To determine if surgical biliary bypass would provide improved quality of residual life and safe palliation in elderly patients with unresectable pancreatic head cancer. METHODS: Nineteen patients, 65 years of age or older, were managed with surgical biliary bypass (Group A). These patients were compared with 19 patients under 65 years of age who were managed with surgical biliary bypass (Group B). In addition, the results for group A were compared with those obtained from 17 patients, 65 years of age or older (Group C), who received percutaneous transhepatic biliary drainage to evaluate the quality of residual life. RESULTS: Five patients (26.0%) in Group A had complications, including one intraabdominal abscess, one pulmonary atelectasis, and three wound infections. One death (5.3%) occurred on postoperative day 3. With respect to morbidity, mortality, and postoperative hospitalization, no statistically significant difference was noted between Groups A and B. The number of readmissions and the rate of recurrent jaundice were lower in Group A than in Group C, to a statistically significant degree (P = 0.019, P = 0.029, respectively). The median hospital-free survival period and themedian overall survival were also signifi cantly longer in Group A (P = 0.001 and P < 0.001, respectively). CONCLUSION: Surgical palliation does not increase the morbidity or mortality rates, but it does increase the survival rate and improve the quality of life in elderly patients with unresectable pancreatic head cancer.展开更多
A traffic matrix is a necessary parameter fornetwork management functions,and itsupplies a flow-level view of a largescale IP-over-WDM backbone network.This paper studies the problem of traffic matrix estimationand pr...A traffic matrix is a necessary parameter fornetwork management functions,and itsupplies a flow-level view of a largescale IP-over-WDM backbone network.This paper studies the problem of traffic matrix estimationand proposes an exact traffic matrix estimation approach based on network tomography techniques.The traditional network tomography model is extended to make it compatible with compressive sensing constraints.First,a stochastic perturbation is introduced in the traditional network tomography inference model.Then,an algorithm is proposed to achieve additional optical link observations via optical bypass techniques.The obtained optical link observations are used as extensions for the perturbed network tomography model to ensure that the synthetic model can meetcompressive sensing constraints.Finally,the traffic matrix is estimated from the synthetic model by means of a compressive sensing recovery algorithm.展开更多
In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature ...In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.展开更多
文摘Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.
文摘AIM: To determine if surgical biliary bypass would provide improved quality of residual life and safe palliation in elderly patients with unresectable pancreatic head cancer. METHODS: Nineteen patients, 65 years of age or older, were managed with surgical biliary bypass (Group A). These patients were compared with 19 patients under 65 years of age who were managed with surgical biliary bypass (Group B). In addition, the results for group A were compared with those obtained from 17 patients, 65 years of age or older (Group C), who received percutaneous transhepatic biliary drainage to evaluate the quality of residual life. RESULTS: Five patients (26.0%) in Group A had complications, including one intraabdominal abscess, one pulmonary atelectasis, and three wound infections. One death (5.3%) occurred on postoperative day 3. With respect to morbidity, mortality, and postoperative hospitalization, no statistically significant difference was noted between Groups A and B. The number of readmissions and the rate of recurrent jaundice were lower in Group A than in Group C, to a statistically significant degree (P = 0.019, P = 0.029, respectively). The median hospital-free survival period and themedian overall survival were also signifi cantly longer in Group A (P = 0.001 and P < 0.001, respectively). CONCLUSION: Surgical palliation does not increase the morbidity or mortality rates, but it does increase the survival rate and improve the quality of life in elderly patients with unresectable pancreatic head cancer.
基金supported in part by the National Natural Science Foundation of China(Nos.61571104,61071124,61501105)the General Project of Scientific Research of the Education Department of Liaoning Province(No.L20150174)+2 种基金the Program for New Century Excellent Talents in University(No.NCET-11-0075)the Fundamental Research Funds for the Central Universities(Nos.N150402003,N120804004,N130504003,N150404018)the State Scholarship Fund(201208210013)
文摘A traffic matrix is a necessary parameter fornetwork management functions,and itsupplies a flow-level view of a largescale IP-over-WDM backbone network.This paper studies the problem of traffic matrix estimationand proposes an exact traffic matrix estimation approach based on network tomography techniques.The traditional network tomography model is extended to make it compatible with compressive sensing constraints.First,a stochastic perturbation is introduced in the traditional network tomography inference model.Then,an algorithm is proposed to achieve additional optical link observations via optical bypass techniques.The obtained optical link observations are used as extensions for the perturbed network tomography model to ensure that the synthetic model can meetcompressive sensing constraints.Finally,the traffic matrix is estimated from the synthetic model by means of a compressive sensing recovery algorithm.
文摘In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.
