This paper is concerned with the issue of stabilization for the linear neutral systems with mixed delays. The attention is focused on the design of output feedback controllers which guarantee the asymptotical stabilit...This paper is concerned with the issue of stabilization for the linear neutral systems with mixed delays. The attention is focused on the design of output feedback controllers which guarantee the asymptotical stability of the closed-loop systems. Based on the model transformation of neutral type, the Lyapunov-Krasovskii functional method is employed to establish the delay-dependent stability criterion. Then, through the controller parameterization and some matrix transformation techniques, the desired parameters are determined under the delay-dependent design condition in terms of linear matrix inequalities (LMIs), and the desired controller is explicitly formulated. A numerical example is given to illustrate the effectiveness of the proposed method.展开更多
Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model ...Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model of PETs and applied it to the power flow calculation of AC-DC hybrid systems with PETs,considering the topology,power balance,loss,and control characteristics of multi-port PETs.To address new problems caused by the introduction of the PET port and control equations to the power flow calculation,this study proposes an iterative method of AC-DC mixed power flow decoupling based on step optimization,which can achieve AC-DC decoupling and effectively improve convergence.The results show that the proposed algorithm improves the iterative method and overcomes the overcorrection and initial value sensitivity problems of conventional iterative algorithms.展开更多
Data envelopment analysis (DEA) has become a standard non parametric approach to productivity analysis, especially to relative efficiency analysis of decision making units (DMUs). Extended to the prediction field, it ...Data envelopment analysis (DEA) has become a standard non parametric approach to productivity analysis, especially to relative efficiency analysis of decision making units (DMUs). Extended to the prediction field, it can solve the prediction problem with multiple inputs and outputs which can not be solved easily by the regression analysis method.But the traditional DEA models can not solve the problem with undesirable outputs,so in this paper the inherent relationship between goal programming and the DEA method based on the relationship between multiple goal programming and goal programming is explored,and a mixed DEA model which can make all factors of inputs and undesirable outputs decrease in different proportions is built.And at the same time,all the factors of desirable outputs increase in different proportions.展开更多
Purpose: Patients scheduled to undergo the transcatheter aortic valve replacement (TAVR) are usually octogenarians with severe co-morbidities and an increased risk of surgery-associated complications. The aim of this ...Purpose: Patients scheduled to undergo the transcatheter aortic valve replacement (TAVR) are usually octogenarians with severe co-morbidities and an increased risk of surgery-associated complications. The aim of this study was to determine the incidence of insufficient oxygen delivery as measured by mixed venous oxygen saturation (SvO2) via invasive continuous cardiopulmonary monitoring and the low cardiac output syndrome (LCOS) in patients undergoing the TAVR procedure. The second objective was to examine how these hemodynamic measurements would change during critical events, such as rapid ventricular pacing (RVP) during this procedure. Methods: This prospective, observational study, examined twenty patients undergoing TAVR under general anesthesia. Hemodynamic variables, SvO2 and the continuous cardiac output (CO) were assessed using pulmonary artery catheter (PAC) and a Vigilance? monitor. Insufficient oxygen delivery was defined as a SvO2 value under 58% and LCOS as a cardiac index (CI) under 2 L/min/m2. Total intravenous anesthesia and hemodynamic management protocol were standardized. RVP was induced twice during the procedure at a frequency of 180 - 200/min. Predefined clinical endpoints were assessed during the procedure and hemodynamic values were analyzed before and after twelve critical events. Results: The data of twenty patients with a mean age of 80 ± 4 years and EuroSCORE 18 ± 10 were analyzed. Fourteen (70%) of the TAVR procedures were performed transapically, the other six (30%) transfemorally. The SvO2 value under 58% (mean 54 ± 6) and the CI under 2 L/min/m2 (mean 1.6 ± 0.2) were detected in 60% of patients (n = 12) before the use of RVP. All of these patients received perioperative inotropic medication and required norepinephrine infusion for maintenance of adequate blood pressure. The SvO2, CO and CI were significantly decreased after the use of RVP (P 2 reverted rapidly to the same level as before the application of RVP (1 min), CO, and CI 10 min later. At the end of the operation SvO2 values were at same level as before RVP and CO and CI were higher than before RVP. Conclusion: A high incidence of insufficient oxygen delivery and low cardiac output syndrome were detected in patients undergoing TAVR procedures. Nonetheless, all hemodynamic values returned rather rapidly to the same level as before the use of the RVP and were at the optimal level at the end of the procedure. According to the current study, the most hemodynamically hazardous steps during TAVR are the use of RVP sequences, the induction of anesthesia and the initiation of surgery.展开更多
This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly imp...This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device.展开更多
风电和抽水蓄能电站联合运行可以平抑风电随机波动、提升风电消纳率。文章针对多个风电场的出力不确定性,采用概率性序列方法进行处理,提出了一种基于厂网协商机制的风电-抽水蓄能联合调度模式,并建立了基于机会约束规划的风电-抽水蓄...风电和抽水蓄能电站联合运行可以平抑风电随机波动、提升风电消纳率。文章针对多个风电场的出力不确定性,采用概率性序列方法进行处理,提出了一种基于厂网协商机制的风电-抽水蓄能联合调度模式,并建立了基于机会约束规划的风电-抽水蓄能互补系统短期优化调度模型。模型以风电-抽水蓄能互补系统总发电收益最大为目标,综合考虑了抽水蓄能电站的水力约束、机组运行约束和系统功率平衡约束。为提高模型求解效率并获得全局最优解,文章将原模型转换为混合整数线性规划(Mixed Integer Linear Programming,MILP)模型,最后使用商业化求解器LINGO进行求解。优化调度结果表明,抽水蓄能电站能够很好的补偿风电出力的波动性,并显著提升互补系统的总发电收益。展开更多
基金the National Natural Science Foundation of China (No. 50708094)the Hi-Tech Research and Development Program (863) of China (No. 2007AA11Z216)
文摘This paper is concerned with the issue of stabilization for the linear neutral systems with mixed delays. The attention is focused on the design of output feedback controllers which guarantee the asymptotical stability of the closed-loop systems. Based on the model transformation of neutral type, the Lyapunov-Krasovskii functional method is employed to establish the delay-dependent stability criterion. Then, through the controller parameterization and some matrix transformation techniques, the desired parameters are determined under the delay-dependent design condition in terms of linear matrix inequalities (LMIs), and the desired controller is explicitly formulated. A numerical example is given to illustrate the effectiveness of the proposed method.
基金supported by the National Key Research and Development Program of China(2017YFB0903300).
文摘Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model of PETs and applied it to the power flow calculation of AC-DC hybrid systems with PETs,considering the topology,power balance,loss,and control characteristics of multi-port PETs.To address new problems caused by the introduction of the PET port and control equations to the power flow calculation,this study proposes an iterative method of AC-DC mixed power flow decoupling based on step optimization,which can achieve AC-DC decoupling and effectively improve convergence.The results show that the proposed algorithm improves the iterative method and overcomes the overcorrection and initial value sensitivity problems of conventional iterative algorithms.
文摘Data envelopment analysis (DEA) has become a standard non parametric approach to productivity analysis, especially to relative efficiency analysis of decision making units (DMUs). Extended to the prediction field, it can solve the prediction problem with multiple inputs and outputs which can not be solved easily by the regression analysis method.But the traditional DEA models can not solve the problem with undesirable outputs,so in this paper the inherent relationship between goal programming and the DEA method based on the relationship between multiple goal programming and goal programming is explored,and a mixed DEA model which can make all factors of inputs and undesirable outputs decrease in different proportions is built.And at the same time,all the factors of desirable outputs increase in different proportions.
文摘Purpose: Patients scheduled to undergo the transcatheter aortic valve replacement (TAVR) are usually octogenarians with severe co-morbidities and an increased risk of surgery-associated complications. The aim of this study was to determine the incidence of insufficient oxygen delivery as measured by mixed venous oxygen saturation (SvO2) via invasive continuous cardiopulmonary monitoring and the low cardiac output syndrome (LCOS) in patients undergoing the TAVR procedure. The second objective was to examine how these hemodynamic measurements would change during critical events, such as rapid ventricular pacing (RVP) during this procedure. Methods: This prospective, observational study, examined twenty patients undergoing TAVR under general anesthesia. Hemodynamic variables, SvO2 and the continuous cardiac output (CO) were assessed using pulmonary artery catheter (PAC) and a Vigilance? monitor. Insufficient oxygen delivery was defined as a SvO2 value under 58% and LCOS as a cardiac index (CI) under 2 L/min/m2. Total intravenous anesthesia and hemodynamic management protocol were standardized. RVP was induced twice during the procedure at a frequency of 180 - 200/min. Predefined clinical endpoints were assessed during the procedure and hemodynamic values were analyzed before and after twelve critical events. Results: The data of twenty patients with a mean age of 80 ± 4 years and EuroSCORE 18 ± 10 were analyzed. Fourteen (70%) of the TAVR procedures were performed transapically, the other six (30%) transfemorally. The SvO2 value under 58% (mean 54 ± 6) and the CI under 2 L/min/m2 (mean 1.6 ± 0.2) were detected in 60% of patients (n = 12) before the use of RVP. All of these patients received perioperative inotropic medication and required norepinephrine infusion for maintenance of adequate blood pressure. The SvO2, CO and CI were significantly decreased after the use of RVP (P 2 reverted rapidly to the same level as before the application of RVP (1 min), CO, and CI 10 min later. At the end of the operation SvO2 values were at same level as before RVP and CO and CI were higher than before RVP. Conclusion: A high incidence of insufficient oxygen delivery and low cardiac output syndrome were detected in patients undergoing TAVR procedures. Nonetheless, all hemodynamic values returned rather rapidly to the same level as before the use of the RVP and were at the optimal level at the end of the procedure. According to the current study, the most hemodynamically hazardous steps during TAVR are the use of RVP sequences, the induction of anesthesia and the initiation of surgery.
文摘This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device.
文摘风电和抽水蓄能电站联合运行可以平抑风电随机波动、提升风电消纳率。文章针对多个风电场的出力不确定性,采用概率性序列方法进行处理,提出了一种基于厂网协商机制的风电-抽水蓄能联合调度模式,并建立了基于机会约束规划的风电-抽水蓄能互补系统短期优化调度模型。模型以风电-抽水蓄能互补系统总发电收益最大为目标,综合考虑了抽水蓄能电站的水力约束、机组运行约束和系统功率平衡约束。为提高模型求解效率并获得全局最优解,文章将原模型转换为混合整数线性规划(Mixed Integer Linear Programming,MILP)模型,最后使用商业化求解器LINGO进行求解。优化调度结果表明,抽水蓄能电站能够很好的补偿风电出力的波动性,并显著提升互补系统的总发电收益。
