In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave th...In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.展开更多
As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude deter...As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude determination.The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory.The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy.Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark,the attitude determination accuracy improves.展开更多
AIM: To assess the tolerability and safety of same-day tandem procedures, endoscopic ultrasound (EUS) followed by endoscopic retrograde cholangiopancreatography (ERCP) under conscious sedation. METHODS: A retrospectiv...AIM: To assess the tolerability and safety of same-day tandem procedures, endoscopic ultrasound (EUS) followed by endoscopic retrograde cholangiopancreatography (ERCP) under conscious sedation. METHODS: A retrospective review was conducted at Loma Linda University Medical Center, a tertiary-care center. All 54 patients who underwent EUS followed by ERCP (group A) from 2004 to 2006 were included in the study. A second group of 56 patients who underwent EUS only (group B), and a third group of 53 patients who underwent ERCP only (group C) during the same time period were selected consecutively as control groups for comparison. RESULTS: Conscious sedation was used in 96% of patients in group A. Mean dosages of meperidine and midazolam used in group A were signifi cantly higher than in group B or C. Mean recovery time in group A was not statistically longer than in group B or C. Therewas no signifi cant difference in the incidence of sedation-related and procedural-related complications. CONCLUSION: Tandem EUS/ERCP procedure can be safely performed under conscious sedation with minimal adverse events. Combined procedures, however, are associated with higher dosages of sedatives, and slightly longer recovery time.展开更多
This paper suggests a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-lectric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chiral...This paper suggests a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-lectric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chirality coefficients having the same amplitude but the opposite phase, without requiring the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency.展开更多
In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based ...In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.展开更多
The theme of this article is mainly to explore the application of the"Sameness Relation"into the Chinese-English trans-lation practice.In view of the theoretical guidance of sameness relation into the practi...The theme of this article is mainly to explore the application of the"Sameness Relation"into the Chinese-English trans-lation practice.In view of the theoretical guidance of sameness relation into the practice of the Chinese-English translation,this pa-per first points out a liable mistake in Chinese-English translation due to an inadequate knowledge of the"Sense Relations",andthen defines the linguistic term"sense relations","Sameness relation""and relevant "Semantics".Next this text continues to ana-lyze how the sameness relations are applied into the translation from the five main aspects.The reference and help of the samenessrelations finally demonstrate the realistic importance of the semantics to the Chinese-English translation,attracting much wider at-tention to other linguistic theories which is great of value to Chinese-English translation.展开更多
Chinese and English are two very different languages; the former belongs to the Sino-Tibetan Language Family and the latter the Indo-European Language Family. In terms of textual organization, they show substantial di...Chinese and English are two very different languages; the former belongs to the Sino-Tibetan Language Family and the latter the Indo-European Language Family. In terms of textual organization, they show substantial differences. Chinese is mainly a pragmatic, paratactic and topic-prominent language, while English a grammatical, hypotactic and subject-prominent language. This thesis gives a contrastive study of two problems in English and Chinese. They are repeated references to the same thing and parallel structure. In this way, the translation work will be more succinct and smooth.展开更多
目的:评估SAMe-TT_2R_2评分预测非瓣膜性房颤患者应用华法林抗凝控制质量的能力,探索SAMe-TT_2R_2评分与缺血性卒中和严重出血的关系。方法:对某院2014年1月-2015年6月初次应用华法林治疗的非瓣膜性房颤患者进行为期1年的随访,计算患者S...目的:评估SAMe-TT_2R_2评分预测非瓣膜性房颤患者应用华法林抗凝控制质量的能力,探索SAMe-TT_2R_2评分与缺血性卒中和严重出血的关系。方法:对某院2014年1月-2015年6月初次应用华法林治疗的非瓣膜性房颤患者进行为期1年的随访,计算患者SAMe-TT_2R_2分数及抗凝治疗范围内时间百分比[the percentage time in therapeutic International Normalised Ratio(INR)range,TTR],运用ANOVA检验,ROC曲线分析评估SAMe-TT_2R_2评分对患者TTR的预测能力。记录随访期间缺血性卒中或严重出血事件发生情况以探寻SAMe-TT_2R_2分数与缺血性卒中和严重出血的关系。结果:178例患者平均TTR为57.79%±15.53%,随着SAMe-TT_2R_2分数增加,患者TTR逐渐下降(P=0.001),SAMe-TT_2R_2预测TTR<70%准确性较高(ROC曲线下面积为0.734,P<0.001),最佳临界值为2,敏感度和特异性分别为95%和36%,Youden指数为最高值0.31,提示当SAMe-TT_2R_2>2时患者抗凝控制质量较差(TTR<70%)。随访期间共有7例患者(3.93%/年)发生缺血性卒中,3例患者(1.69%/年)发生严重出血。Kaplan-Meier生存分析提示SAMe-TT_2R_2评分与患者缺血性卒中年发生率无明显相关(Log Rank=1.653,P=0.647)。结论:在应用华法林抗凝的非瓣膜性房颤患者中,SAMe-TT_2R_2评分具有预测TTR的能力,针对抗凝控制质量较差患者,临床药师应为其制定个体化用药方案,改善抗凝质量。展开更多
文摘In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.
文摘As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude determination.The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory.The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy.Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark,the attitude determination accuracy improves.
文摘AIM: To assess the tolerability and safety of same-day tandem procedures, endoscopic ultrasound (EUS) followed by endoscopic retrograde cholangiopancreatography (ERCP) under conscious sedation. METHODS: A retrospective review was conducted at Loma Linda University Medical Center, a tertiary-care center. All 54 patients who underwent EUS followed by ERCP (group A) from 2004 to 2006 were included in the study. A second group of 56 patients who underwent EUS only (group B), and a third group of 53 patients who underwent ERCP only (group C) during the same time period were selected consecutively as control groups for comparison. RESULTS: Conscious sedation was used in 96% of patients in group A. Mean dosages of meperidine and midazolam used in group A were signifi cantly higher than in group B or C. Mean recovery time in group A was not statistically longer than in group B or C. Therewas no signifi cant difference in the incidence of sedation-related and procedural-related complications. CONCLUSION: Tandem EUS/ERCP procedure can be safely performed under conscious sedation with minimal adverse events. Combined procedures, however, are associated with higher dosages of sedatives, and slightly longer recovery time.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60768001 and 10464002)
文摘This paper suggests a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-lectric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chirality coefficients having the same amplitude but the opposite phase, without requiring the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency.
文摘In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.
文摘The theme of this article is mainly to explore the application of the"Sameness Relation"into the Chinese-English trans-lation practice.In view of the theoretical guidance of sameness relation into the practice of the Chinese-English translation,this pa-per first points out a liable mistake in Chinese-English translation due to an inadequate knowledge of the"Sense Relations",andthen defines the linguistic term"sense relations","Sameness relation""and relevant "Semantics".Next this text continues to ana-lyze how the sameness relations are applied into the translation from the five main aspects.The reference and help of the samenessrelations finally demonstrate the realistic importance of the semantics to the Chinese-English translation,attracting much wider at-tention to other linguistic theories which is great of value to Chinese-English translation.
文摘Chinese and English are two very different languages; the former belongs to the Sino-Tibetan Language Family and the latter the Indo-European Language Family. In terms of textual organization, they show substantial differences. Chinese is mainly a pragmatic, paratactic and topic-prominent language, while English a grammatical, hypotactic and subject-prominent language. This thesis gives a contrastive study of two problems in English and Chinese. They are repeated references to the same thing and parallel structure. In this way, the translation work will be more succinct and smooth.
文摘目的:评估SAMe-TT_2R_2评分预测非瓣膜性房颤患者应用华法林抗凝控制质量的能力,探索SAMe-TT_2R_2评分与缺血性卒中和严重出血的关系。方法:对某院2014年1月-2015年6月初次应用华法林治疗的非瓣膜性房颤患者进行为期1年的随访,计算患者SAMe-TT_2R_2分数及抗凝治疗范围内时间百分比[the percentage time in therapeutic International Normalised Ratio(INR)range,TTR],运用ANOVA检验,ROC曲线分析评估SAMe-TT_2R_2评分对患者TTR的预测能力。记录随访期间缺血性卒中或严重出血事件发生情况以探寻SAMe-TT_2R_2分数与缺血性卒中和严重出血的关系。结果:178例患者平均TTR为57.79%±15.53%,随着SAMe-TT_2R_2分数增加,患者TTR逐渐下降(P=0.001),SAMe-TT_2R_2预测TTR<70%准确性较高(ROC曲线下面积为0.734,P<0.001),最佳临界值为2,敏感度和特异性分别为95%和36%,Youden指数为最高值0.31,提示当SAMe-TT_2R_2>2时患者抗凝控制质量较差(TTR<70%)。随访期间共有7例患者(3.93%/年)发生缺血性卒中,3例患者(1.69%/年)发生严重出血。Kaplan-Meier生存分析提示SAMe-TT_2R_2评分与患者缺血性卒中年发生率无明显相关(Log Rank=1.653,P=0.647)。结论:在应用华法林抗凝的非瓣膜性房颤患者中,SAMe-TT_2R_2评分具有预测TTR的能力,针对抗凝控制质量较差患者,临床药师应为其制定个体化用药方案,改善抗凝质量。
