Reasonable probability assessment of transformer failure rate (FR) is a critical reference to the transformer replacement work. At present, the lack of support theory for transformer replacement usually causes reliabi...Reasonable probability assessment of transformer failure rate (FR) is a critical reference to the transformer replacement work. At present, the lack of support theory for transformer replacement usually causes reliability and economy issues for power companies. For this reason, a transformer replacement decision method based on probability assessment of FR is proposed. Firstly, a first order model of transformer paper degradation is proposed. Then, the Weibull Distribution is used by Monte Carlo Simulation (MCS) to generate the variations of Degree of Polymerization (DP) along with time based on the historical data, and the transformer FR is determined. When the FR is higher than a pre-defined threshold value, the transformer should be replaced for reliability purpose. Finally, the effectiveness of the proposed method for the transformer replacement decision is verified by a typical engineering application.展开更多
Geodynamic studies have shown that mantle convection is like a giant blender to make the original heterogeneous mantle mixing and homogenizing. However, some models, especially from geochemical data show that the mode...Geodynamic studies have shown that mantle convection is like a giant blender to make the original heterogeneous mantle mixing and homogenizing. However, some models, especially from geochemical data show that the modem mantle may still contain a number of reservoir bodies with different chemical composition. Then, the modern mantle is homogeneous？ Authors have defined a box replacement degree of convective mantle mixing and pervasion degree of convective mantle mixing （that equals to initial density of tracing elements divided by final density of tracing elements） to investigate the mantle mixing. The previous results have shown that after four billion years the mantle is basic uniform and the box replacement of the convective mantle is more than 80% in steady-state convection models. This paper calculates and discusses the pervasion degree of convective mantle mixing in detail. For the initial state we will set some 10°× 10°（spacing 0.25°） tracing boxes, which includes 1 681 tracer, at the top and bottom of the mantle, and then track the motions of these tracers, and investigate the convective mixed pervasions. The results show that at the initial stage though the convective mixing pervasions are very different from mode to mode, after running for some time, the convective mixing pervasions for most modes are going to be a constant and the tracers are more evenly distributed in the whole mantle.展开更多
Approximately 3%-11.8% of cases require permanent pacemaker implantation due to atrioventricular block (AVB) after aortic valve replacement (AVR), and determination of conduction disturbances such as left or right bun...Approximately 3%-11.8% of cases require permanent pacemaker implantation due to atrioventricular block (AVB) after aortic valve replacement (AVR), and determination of conduction disturbances such as left or right bundle branch block by preoperative electrocardiography is correlated with high risk postoperative permanent pacemaker implantation. Intraoperative risk factors include severe calcification of the aortic valve, prolonged cardiopulmonary bypass time, aortic clamp time. Recently, there have been reports of high rates of pacemaker implantation (14.2%) after transcatheter aortic valve implantation. The time of permanent pacemaker implantation after AVB is often 4-10 days, and the European Society of Cardiology guidelines recommend a period of seven days of persistent atrioventricular block postsurgery prior to permanent pacemaker implantation. We report a 79-year-old woman in which the patient developed high-degree AVB after AVR was performed for severe aortic stenosis with complete right bundle branch block. However, her pulse returned to sinus rhythm 7 days postsurgery.展开更多
In-network caching is one of the most important issues in content centric networking （CCN）, which may extremely influence the performance of the caching system. Although much work has been done for in-network cachin...In-network caching is one of the most important issues in content centric networking （CCN）, which may extremely influence the performance of the caching system. Although much work has been done for in-network caching scheme design in CCN, most of them have not addressed the multiple network attribute parameters jointly during caching algorithm design. Hence, to fill this gap, a new in-network caching based on grey relational analysis （GRA） is proposed. The authors firstly define two newly metric parameters named request influence degree （RID） and cache replacement rate, respectively. The RID indicates the importance of one node along the content delivery path from the view of the interest packets arriving The cache replacement rate is used to denote the caching load of the node. Then combining hops a request traveling from the users and the node traffic, four network attribute parameters are considered during the in-network caching algorithm design. Based on these four network parameters, a GRA based in-network caching algorithm is proposed, which can significantly improve the performance of CCN. Finally, extensive simulation based on ndnSIM is demonstrated that the GRA-based caching scheme can achieve the lower load in the source server and the less average hops than the existing the betweeness （Betw） scheme and the ALWAYS scheme.展开更多
文摘Reasonable probability assessment of transformer failure rate (FR) is a critical reference to the transformer replacement work. At present, the lack of support theory for transformer replacement usually causes reliability and economy issues for power companies. For this reason, a transformer replacement decision method based on probability assessment of FR is proposed. Firstly, a first order model of transformer paper degradation is proposed. Then, the Weibull Distribution is used by Monte Carlo Simulation (MCS) to generate the variations of Degree of Polymerization (DP) along with time based on the historical data, and the transformer FR is determined. When the FR is higher than a pre-defined threshold value, the transformer should be replaced for reliability purpose. Finally, the effectiveness of the proposed method for the transformer replacement decision is verified by a typical engineering application.
基金supported by National Natural Science Foundation of China (40574043)
文摘Geodynamic studies have shown that mantle convection is like a giant blender to make the original heterogeneous mantle mixing and homogenizing. However, some models, especially from geochemical data show that the modem mantle may still contain a number of reservoir bodies with different chemical composition. Then, the modern mantle is homogeneous？ Authors have defined a box replacement degree of convective mantle mixing and pervasion degree of convective mantle mixing （that equals to initial density of tracing elements divided by final density of tracing elements） to investigate the mantle mixing. The previous results have shown that after four billion years the mantle is basic uniform and the box replacement of the convective mantle is more than 80% in steady-state convection models. This paper calculates and discusses the pervasion degree of convective mantle mixing in detail. For the initial state we will set some 10°× 10°（spacing 0.25°） tracing boxes, which includes 1 681 tracer, at the top and bottom of the mantle, and then track the motions of these tracers, and investigate the convective mixed pervasions. The results show that at the initial stage though the convective mixing pervasions are very different from mode to mode, after running for some time, the convective mixing pervasions for most modes are going to be a constant and the tracers are more evenly distributed in the whole mantle.
文摘Approximately 3%-11.8% of cases require permanent pacemaker implantation due to atrioventricular block (AVB) after aortic valve replacement (AVR), and determination of conduction disturbances such as left or right bundle branch block by preoperative electrocardiography is correlated with high risk postoperative permanent pacemaker implantation. Intraoperative risk factors include severe calcification of the aortic valve, prolonged cardiopulmonary bypass time, aortic clamp time. Recently, there have been reports of high rates of pacemaker implantation (14.2%) after transcatheter aortic valve implantation. The time of permanent pacemaker implantation after AVB is often 4-10 days, and the European Society of Cardiology guidelines recommend a period of seven days of persistent atrioventricular block postsurgery prior to permanent pacemaker implantation. We report a 79-year-old woman in which the patient developed high-degree AVB after AVR was performed for severe aortic stenosis with complete right bundle branch block. However, her pulse returned to sinus rhythm 7 days postsurgery.
基金supported by the National Basic Research Programs of China(2012CB315801,2011CB302901)the Fundamental Research Funds for the Central Universities(2013RC0113,2012RC0120)
文摘In-network caching is one of the most important issues in content centric networking （CCN）, which may extremely influence the performance of the caching system. Although much work has been done for in-network caching scheme design in CCN, most of them have not addressed the multiple network attribute parameters jointly during caching algorithm design. Hence, to fill this gap, a new in-network caching based on grey relational analysis （GRA） is proposed. The authors firstly define two newly metric parameters named request influence degree （RID） and cache replacement rate, respectively. The RID indicates the importance of one node along the content delivery path from the view of the interest packets arriving The cache replacement rate is used to denote the caching load of the node. Then combining hops a request traveling from the users and the node traffic, four network attribute parameters are considered during the in-network caching algorithm design. Based on these four network parameters, a GRA based in-network caching algorithm is proposed, which can significantly improve the performance of CCN. Finally, extensive simulation based on ndnSIM is demonstrated that the GRA-based caching scheme can achieve the lower load in the source server and the less average hops than the existing the betweeness （Betw） scheme and the ALWAYS scheme.
