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电压骤降的可靠性评估新方法 被引量:32
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作者 张鹏 郭永基 《电力系统自动化》 EI CSCD 北大核心 2002年第8期20-24,共5页
随着信息技术和其他高科技产业的迅速发展 ,电压骤降的影响日趋严重 ,对供电可靠性提出了新的挑战。文中提出了电力系统电压骤降的概率评估指标体系和算法。算法利用电力系统的可靠性数据 ,对于每条可能发生故障的线路 ,考虑保护设备的... 随着信息技术和其他高科技产业的迅速发展 ,电压骤降的影响日趋严重 ,对供电可靠性提出了新的挑战。文中提出了电力系统电压骤降的概率评估指标体系和算法。算法利用电力系统的可靠性数据 ,对于每条可能发生故障的线路 ,考虑保护设备的参数及各种故障类型 ,以一定的步长对该线路进行逐段分析 ,得到电压骤降的参数 ,应用频率与持续时间法求得负荷点和系统的各项指标。算法提供的定量分析结果对于电力部门和用户在规划、运行阶段进行成本 /效益的定量投资分析。 展开更多
关键词 电压骤降 概率评估 频率 持续时间法 可靠性 电力系统
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基于遥感影像的雪线高程提取方法对比分析——以天山北坡为例 被引量:6
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作者 张连成 胡列群 +2 位作者 李帅 郑照军 侯小刚 《干旱区地理》 CSCD 北大核心 2015年第4期788-796,共9页
利用2010-2014年6-8月MOD10A1、MOD10A2及HJ-1/CCD数据,以天山北坡为研究区,对比分析了积雪持续时间比率法及最大值合成法在雪线高程提取中的精度和适用性。结果表明:当MOD10A1以旬合成,积雪持续时间比率阈值为40%时,提取的雪线高程与... 利用2010-2014年6-8月MOD10A1、MOD10A2及HJ-1/CCD数据,以天山北坡为研究区,对比分析了积雪持续时间比率法及最大值合成法在雪线高程提取中的精度和适用性。结果表明:当MOD10A1以旬合成,积雪持续时间比率阈值为40%时,提取的雪线高程与"真值"最为接近;基于混淆矩阵法,以目视解译得到的HJ-1/CCD积雪面积为"真值",分析得出,积雪持续时间比率法提取积雪面积的总体精度较高,为98.59%,khat系数为0.90,最大值合成法的总体精度仅为85.29%,khat系数为0.70;基于统计学的方法,计算得出,积雪持续时间比率法提取的雪线高程与"真值"的相关系数较高,为0.77,其平均误差、正、负误差、绝对平均误差以及均方根误差相对较低;最大值合成法提取的雪线高程与"真值"的相关系数较低,仅为0.54,其平均误差、正、负误差、绝对平均误差以及均方根误差相对较高;积雪持续时间比率法提取的雪线高程结果优于最大值合成法。 展开更多
关键词 雪线 积雪持续时间比率 最大值合成 天山北坡
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离散时间风险模型的递推公式(英文) 被引量:2
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作者 高明美 赵明清 《经济数学》 2002年第4期8-13,共6页
在本文中 ,我们研究了含有投资和通货膨胀因素的离散时间风险模型 ,通过递推的方法 ,得到了有限时间内的破产概率、破产时间的分布、破产持续时间的分布的递推公式 .
关键词 离散时间风险模型 破产概率 破产时间的分布 破产持续时间分布 递推算
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应用马尔科夫模型评估电力变压器可靠性 被引量:62
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作者 廖瑞金 肖中男 +2 位作者 巩晶 杨丽君 王有元 《高电压技术》 EI CAS CSCD 北大核心 2010年第2期322-328,共7页
为对电力变压器进行可靠性评估,首次提出了基于马尔科夫过程的电力变压器可靠性评估模型。该法将变压器所处的使用状态分为正常运行、绕组故障、预防性试验等11种状态,针对变压器可靠性指标统计数据,结合马尔科夫过程,同时运用频率和持... 为对电力变压器进行可靠性评估,首次提出了基于马尔科夫过程的电力变压器可靠性评估模型。该法将变压器所处的使用状态分为正常运行、绕组故障、预防性试验等11种状态,针对变压器可靠性指标统计数据,结合马尔科夫过程,同时运用频率和持续时间法,建立了综合的变压器可靠性评估模型。通过对变压器可能所处的各个状态概率和其它一些可靠性指标的计算,验证了该模型的正确性。基于马尔科夫过程的电力变压器可靠性评估模型能较准确客观地对变压器可靠性进行量化评估,并且计算简单,具有较强的可操作性,所提出的评估方法为全面分析变压器状态从而制定变压器维护维修策略提供了理论支持。 展开更多
关键词 马尔科夫过程 电力变压器 可靠性 使用状态 频率和持续时间法 状态概率 绕组
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New developments in immunotherapy for lymphoma 被引量:6
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作者 Benjamin Heyman Yiping Yang 《Cancer Biology & Medicine》 SCIE CAS CSCD 2018年第3期189-209,共21页
The development of immunotherapies for lymphoma has undergone a revolutionary evolution over the past decades. Since the advent of rituximab as the first successful immunotherapy for B-cell non-Hodgkin lymphoma over t... The development of immunotherapies for lymphoma has undergone a revolutionary evolution over the past decades. Since the advent of rituximab as the first successful immunotherapy for B-cell non-Hodgkin lymphoma over two decades ago, a plethora of new immunotherapeutic approaches to treat lymphoma has ensued. Four of the most exciting classes of immunotherapies include:chimeric antigen receptor T-cells, bispecific antibodies, immune checkpoint inhibitors, and vaccines. However, with addition of these novel therapies the appropriate timing of treatment, optimal patient population, duration of therapy, toxicity, and cost must be considered. In this review, we describe the most-promising immunotherapeutic approaches for the treatment of lymphoma in clinical development, specifically focusing on clinical trials performed to date and strategies for improvement. 展开更多
关键词 CAR-T cells immune checkpoint blockade bispecific antibodies
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INFLUENCE OF DIFFERENT NEEDLE-RETAINING DURATION ON CEREBRAL HEMODYNAMICS OF CEREBRAL PARALYSIS CHILDREN 被引量:1
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作者 袁青 王琴玉 +3 位作者 冯健强 张壮涛 陈雪云 靳瑞 《World Journal of Acupuncture-Moxibustion》 2004年第2期7-10,共4页
Objective: To investigate the effects of different needle-retaining duration on cerebral hemodynamics in cerebral paralysis (CP) children. Methods: A total of 20 cases of CP children were subjected into this study. Ch... Objective: To investigate the effects of different needle-retaining duration on cerebral hemodynamics in cerebral paralysis (CP) children. Methods: A total of 20 cases of CP children were subjected into this study. Changes of systolic peak value (Vs), blood flow velocity at the end-diastolic phase (Ved), mean velocity (Vm), pulsation index (PI) and resistance index (RI) of the cerebral hemodynamics before and after performing JIN’s Three-Needling Therapy with the needles retained for 30 min (group A) and 5 min (group B) were observed by using transcranial Doppler ultrasonography (TCD). Results: After acupuncture, the blood flow in the middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA) was accelerated, and the resistance of blood vessels decreased. The effect of needle-retaining-30 min was better than that of needle-retaining-5 min. Conclusion: In treating cerebral paralysis by using JIN’s Three-Needling Therapy, sufficient stimulation provided by needle remaining is an important factor for achieving satisfactory therapeutic effects. 展开更多
关键词 JIN's Three-Needling Therapy Cerebral paralysis Time-effect relation Transcranial Doppler ultrasonography (TCD)
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Research on Frequency of the Aftershock Sequence of the Wenchuan Earthquake Based on Coseismic Coulomb Stress Change
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作者 Jia Ruo Jiang Haikun 《Earthquake Research in China》 CSCD 2015年第1期84-102,共19页
By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "af... By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas nearby.It shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress change.The study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit magnitude.The duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above ML3.5.In this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress changes.It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases. 展开更多
关键词 Wenchuan earthquake Static Coulomb failure stress change "Direct"aftershock frequency Aftershock spatial distribution Afterslip
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Empowering Women on the Chars: Increasing Resilience to Disasters and Building Sustainable Livelihoods
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作者 Matthew Pritchard Arifur Rahman Mahbub Alam 《Journal of Agricultural Science and Technology(A)》 2015年第4期246-251,共6页
The Chars Livelihoods Programme (CLP)'s response has been to provide a comprehensive package of support, which aims to increase resilience to disasters and build women's empowerment. In 2012, CLP developed an inno... The Chars Livelihoods Programme (CLP)'s response has been to provide a comprehensive package of support, which aims to increase resilience to disasters and build women's empowerment. In 2012, CLP developed an innovative approach to monitor women's empowerment. Understanding that empowerment is context specific, therefore CLP used qualitative approaches to understand how char households define empowerment. From this research, CLP developed a set of 10 (community and household level) indicators, which made up the chars empowerment scorecard. Results show that CLP has a considerable impact on women's empowennent. They also show that CLP has impacts at both the household and community level, driven by two main factors: increased knowledge (through social development training) and increased wealth (through CLP's Asset Transfer Project). Further, impacts on empowerment are seen to occur relatively quickly and sustain over time. The effects of climate change are only likely to further compound problems for char-dwellers. By increasing women's empowerment, CLP is confident that they will be better able to build sustainable livelihoods and increase their resilience to future disasters. 展开更多
关键词 GENDER EMPOWERMENT livelihoods sustainability Bangladesh.
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Measurement and characteristics of ground vibration caused by blasting demolition of urban overpass
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作者 Hu Jinjun Yang Yongqiang Guan Yingjun 《Engineering Sciences》 EI 2014年第6期100-106,共7页
To analyze the characteristics of ground vibration caused by blasting demolition of urban overpass, in this paper we introduced the measurement method and then studied the characteristics of recorded ground vi- bratio... To analyze the characteristics of ground vibration caused by blasting demolition of urban overpass, in this paper we introduced the measurement method and then studied the characteristics of recorded ground vi- brations. Through the analysis of peak acceleration, peak frequency and duration, results indicated that the ver- tical component of vibration is the most important in the region close to the collapse point; the collapse of bridge segments will lead to superposition of ground vibration, and isolation measures can reduce the peak ac- celeration but increase the duration of vibration; blasting and collapse vibration cause no damage to the re- served structure which indicates that blastin~ demolition is a safe and effective method. 展开更多
关键词 blasting demolition urban overpass COLLAPSE ground vibration ACCELERATION
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中国家庭长期多维贫困状态转化及教育因素研究 被引量:30
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作者 周强 张全红 《数量经济技术经济研究》 CSSCI CSCD 北大核心 2017年第4期3-19,共17页
研究目标:分析教育因素对长期多维贫困的影响。研究方法:结合Foster(2009)持续时间分析法和A-F双界线法构建了长期多维贫困指数,并选取混合效应回归模型、明瑟收入方程及其改进形式,重点分析家庭教育因素对长期多维贫困的影响。研究发现... 研究目标:分析教育因素对长期多维贫困的影响。研究方法:结合Foster(2009)持续时间分析法和A-F双界线法构建了长期多维贫困指数,并选取混合效应回归模型、明瑟收入方程及其改进形式,重点分析家庭教育因素对长期多维贫困的影响。研究发现:教育已经成为长期多维贫困的主要贡献因素,其贡献度随着贫困持续时间的增加而增加。教育水平不同导致教育回报率差异进而影响贫困家庭贫困剥夺深度和贫困持续时间差异,并且高中及以上学历的教育回报率呈明显递增趋势。研究创新:将多维贫困在静态时点上的测度拓展到跨期的动态测度,并从微观家庭所在社区(村)拥有的教育资源和各级教育回报率差异等方面剖析了家庭陷入长期多维贫困的原因。研究价值:为构建长期多维贫困指数和促进"精准扶贫、精准脱贫"提供理论参考。 展开更多
关键词 长期多维贫困 A-F双界线 持续时间法 教育机会 教育回报率
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新疆雪线场的建立及其空间分布特征 被引量:1
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作者 张连成 胡列群 +2 位作者 李帅 侯小刚 郑照军 《干旱区研究》 CSCD 北大核心 2018年第4期840-845,共6页
以新疆为研究区,利用2015年逐日积雪产品MOD10A1/MYD10A1数据,通过积雪持续时间比率法提取研究区雪线,并运用克里金插值法建立新疆区域雪线场,在此基础上对研究区雪线空间分布特征进行研究。经分析得出:普通克里格插值法建立的新疆雪线... 以新疆为研究区,利用2015年逐日积雪产品MOD10A1/MYD10A1数据,通过积雪持续时间比率法提取研究区雪线,并运用克里金插值法建立新疆区域雪线场,在此基础上对研究区雪线空间分布特征进行研究。经分析得出:普通克里格插值法建立的新疆雪线场MAE(平均绝对误差)为4.49 m,RMSE(均方根误差)为48.93 m,其误差满足本研究的精度需求;从整个研究区分析,雪线高程呈现出北低南高,西高东低的布局,其值在3 000-5 600m,具有典型的经度地带性和纬度地带性的分布特点,同时雪线场南部分布密集北部稀疏;从局部区域分析,天山山区雪线高程南高北低、东高西低,昆仑山区中间高、两边低,阿尔泰山区西北向东南依次降低;各个区域雪线分布差异较大,其内部分布复杂,雪线高程高低交错。 展开更多
关键词 雪线场 空间分布 积雪持续时间比率 新疆
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A Big Stride Forward
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作者 Lan Xinzhen 《Beijing Review》 2018年第13期10-13,共4页
Annual political gatherings usher in a new era of development The First Session of the 13th National People’s Congress(NPC),China’s top legislature,came to a close in Beijing on March 20.Over the two weeks of its ... Annual political gatherings usher in a new era of development The First Session of the 13th National People’s Congress(NPC),China’s top legislature,came to a close in Beijing on March 20.Over the two weeks of its duration. 展开更多
关键词 FORWARD POLITICAL LEADERSHIP institutions governance mankind SUPERVISION DEMOCRACY chairman PROSPEROUS
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Predictors of early outcome in unstable pelvic fractures
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作者 Ramesh K. Sen Nirmal Raj Gopinathan +3 位作者 Tajir Tamuk Rajesh Kumar Vibhu Krishnan Radheshyam Sament 《Chinese Journal of Traumatology》 CAS CSCD 2013年第2期94-98,共5页
Objective: To define the preoperative and intraoperative variables which may affect the immediate postoperative outcome in surgically managed patients with unstable pelvic fractures. Methods: This study was perform... Objective: To define the preoperative and intraoperative variables which may affect the immediate postoperative outcome in surgically managed patients with unstable pelvic fractures. Methods: This study was performed prospectively from January 2009 to June 2011 on 36 consecutive patients admitted to the trauma ward of Postgraduate Institute of Medical Education and Research, Chandigarh, with unstable pelvic injuries. Results: In the present study of 36 patients, 29 were managed surgically. Surgical duration was 2 hours in pa- tients operated on within 1 week and 3.4 hours in those operated on after 1 week. The blood loss was 550 ml when surgery was done after a week, but when done within a week it was 350 ml. The average blood loss through Pfanenstial approach was 360 ml, through posterior approach was 408 ml and through combined approach was 660 ml which was significantly high. Conclusion: Anterior approach to the pelvis would cause significantly more amount of blood loss than poste- rior approach and extemal fixation. Surgical approaches do not have any influence on the surgical duration or the infec- tion rate. The blood loss significantly increases when the surgical time is more than 1 h. The infection rate is not influ- enced by the duration of surgery. Presence or absence of associated injuries to the head, chest or abdomen is the main determinants of patient's survival and it greatly influ- ences the duration of hospital stay. 展开更多
关键词 PELVIS Fractures bone TREATMENTOUTCOME Pubic symphysis
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