To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a syn...To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.展开更多
Let {Xn, n ≥ 1} be a sequence of independent and identically distributed positive valued random variables with a common distribution function F. When F belongs to the domain of partial attraction of a semi stable law...Let {Xn, n ≥ 1} be a sequence of independent and identically distributed positive valued random variables with a common distribution function F. When F belongs to the domain of partial attraction of a semi stable law with index α, 0 < α < 1, an asymptotic behavior of the large deviation probabilities with respect to properly normalized weighted sums have been studied and in support of this we obtained Chover’s form of law of iterated logarithm.展开更多
In this paper,we prove a large deviation principle for a class of stochastic Cahn-Hilliard partial differential equations driven by space-time white noises.
目的比较不同鼻内镜下手术方法治疗变应性鼻炎(AR)伴鼻中隔偏曲的效果。方法将2014年12月至2017年1月间中山市小榄人民医院诊治的100例AR伴鼻中隔偏曲患者根据随机数表法分为观察组和对照组各50例,观察组行鼻内镜下鼻中隔黏膜下切除术...目的比较不同鼻内镜下手术方法治疗变应性鼻炎(AR)伴鼻中隔偏曲的效果。方法将2014年12月至2017年1月间中山市小榄人民医院诊治的100例AR伴鼻中隔偏曲患者根据随机数表法分为观察组和对照组各50例,观察组行鼻内镜下鼻中隔黏膜下切除术联合下鼻甲黏膜下海绵体部分切除术,对照组行常规鼻内镜下鼻中隔黏膜下切除术,比较两组患者术后1个月的疗效及并发症发生情况。结果观察组和对照组患者术后症状积分[(1.32±0.36)分vs(1.61±0.39)分]和体征积分[(1.24±0.27)分vs (1.87±0.43)分]比较,观察组均明显低于对照组,差异均有统计学意义(P<0.05);观察组和对照组患者术后糖精清除率[(16.32±2.16) min vs (17.61±2.25) min]、鼻腔阻力[(0.30±0.09) kPa/(L·s) vs (0.47±0.11) k Pa/(L·s)]比较,观察组均明显低于对照组,差异有统计学意义(P<0.05);观察组患者的治疗总有效率为94.0%,明显高于对照组的84.0%,差异具有统计学意义(P<0.05);观察组患者术后并发症发生率为2.0%,略低于对照组的10.0%,但差异无统计学意义(P>0.05)。结论鼻内镜下鼻中隔黏膜下切除术联合下鼻甲黏膜下海绵体部分切除术治疗AR伴鼻中隔偏曲可显著改善患者临床症状,效果优于单独鼻中隔黏膜下切除术。展开更多
基金the National Natural Science Foundation of China under Grant 52007071 and 51907073the China Postdoctoral Science Foundation under Grant 3004131154 and 2020M672355the Applied Basic Frontier Program of Wuhan under Grant 2020010601012207。
文摘To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.
文摘Let {Xn, n ≥ 1} be a sequence of independent and identically distributed positive valued random variables with a common distribution function F. When F belongs to the domain of partial attraction of a semi stable law with index α, 0 < α < 1, an asymptotic behavior of the large deviation probabilities with respect to properly normalized weighted sums have been studied and in support of this we obtained Chover’s form of law of iterated logarithm.
基金Supported by the LPMC at Nankai Universitythe NSF of China(Grant No.10871103)
文摘In this paper,we prove a large deviation principle for a class of stochastic Cahn-Hilliard partial differential equations driven by space-time white noises.
文摘目的比较不同鼻内镜下手术方法治疗变应性鼻炎(AR)伴鼻中隔偏曲的效果。方法将2014年12月至2017年1月间中山市小榄人民医院诊治的100例AR伴鼻中隔偏曲患者根据随机数表法分为观察组和对照组各50例,观察组行鼻内镜下鼻中隔黏膜下切除术联合下鼻甲黏膜下海绵体部分切除术,对照组行常规鼻内镜下鼻中隔黏膜下切除术,比较两组患者术后1个月的疗效及并发症发生情况。结果观察组和对照组患者术后症状积分[(1.32±0.36)分vs(1.61±0.39)分]和体征积分[(1.24±0.27)分vs (1.87±0.43)分]比较,观察组均明显低于对照组,差异均有统计学意义(P<0.05);观察组和对照组患者术后糖精清除率[(16.32±2.16) min vs (17.61±2.25) min]、鼻腔阻力[(0.30±0.09) kPa/(L·s) vs (0.47±0.11) k Pa/(L·s)]比较,观察组均明显低于对照组,差异有统计学意义(P<0.05);观察组患者的治疗总有效率为94.0%,明显高于对照组的84.0%,差异具有统计学意义(P<0.05);观察组患者术后并发症发生率为2.0%,略低于对照组的10.0%,但差异无统计学意义(P>0.05)。结论鼻内镜下鼻中隔黏膜下切除术联合下鼻甲黏膜下海绵体部分切除术治疗AR伴鼻中隔偏曲可显著改善患者临床症状,效果优于单独鼻中隔黏膜下切除术。
