Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it...Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it is important to investigate the ranking of hottest years. In this study, the Wilcoxon signed-ranktest and Monte Carlo simulation are used to estimate the ranking of the hottest years for theTibetan Plateau （TP） in recent decades, and the uncertainty in the ranking.The Wilcoxon signed-rank test shows that the top 10 hottest years on record over the TP mainly occur after 1998. The top three hottest years are ranked as 2006, 2009, and 2010, but there is almost no significant difference between them. When both sampling and observational errors are considered, only five years have a non-zero probability of being the hottest year, with the three highest probabilities being for the years 2006 （-47.231%）, 2009 （-40.390%）, and 2010 （-12.376%）. Similarly, with respect to a given year that is among the 10 hottest years, our results show that all the years among the ranks of 1-10 resulting from the Wilcoxon signed-rank test have probabilities above 10%, while the years 2001 and 2012 have probabilities of 3% and 4%.展开更多
为分析高压电容式油气套管内部暂态温度与其短时载流能力的关系,提出了适用于高压油气套管结构的集总RC热网络模型。该模型计及传导、对流和辐射3种传热方式,考虑了材料性能随温度的变化关系,并基于MATLAB/Simulink实现了热网络拓扑结...为分析高压电容式油气套管内部暂态温度与其短时载流能力的关系,提出了适用于高压油气套管结构的集总RC热网络模型。该模型计及传导、对流和辐射3种传热方式,考虑了材料性能随温度的变化关系,并基于MATLAB/Simulink实现了热网络拓扑结构。以550 k V油/SF6套管为例,暂态温度热网络计算结果与实际温升试验结果吻合较好,证明了集总RC热网络的有效性和实用性,通过阶梯载荷曲线拟合昼夜周期变化负载,并结合热网络确定了油气套管最热点温度的周期暂态变化规律。研究表明油气套管最热点位于中心导杆与绝缘芯子界面处,且各载荷步下套管暂态温度值与稳态温度值存在较大差异。将集总RC热网络方法应用于油气套管暂态温度计算,补充了仅考虑稳态额定运行条件的传统套管设计方法,对分析油气套管运行中的短时载流能力有一定理论指导作用。展开更多
China witnessed a warm and dry climate in 2023.The annual surface air temperature reached a new high of 10.71℃,with the hottest autumn and the second hottest summer since 1961.Meanwhile,the annual precipitation was t...China witnessed a warm and dry climate in 2023.The annual surface air temperature reached a new high of 10.71℃,with the hottest autumn and the second hottest summer since 1961.Meanwhile,the annual precipitation was the second lowest since 2012,at 615.0 mm.Precipitation was less than normal from winter to summer,but more in autumn.Consistent with the annual condition,precipitation in the flood season from May to September was also the second lowest since 2012,which was 4.3%less than normal,with the anomalies in the central and eastern parts of China being higher in central areas and lower in the north and south.On the contrary,the West China Autumn Rain brought much more rainfall than normal,with an earlier start and later end.Although there was less annual precipitation in 2023,China suffered seriously from heavy precipitation events and floods.In particular,from the end of July to the beginning of August,a rare,extremely strong rainstorm caused by Typhoon Dussuri hit Beijing,Tianjin,and Hebei,causing an abrupt alteration from drought to flood conditions in North China.By contrast,Southwest China experienced continuous drought from the previous autumn to current spring.In early summer,North China and the Huanghuai region experienced the strongest high-temperature process since 1961.Nevertheless,there were more cold-air processes than normal impacting China,with the most severe of the year occurring in mid-January.Unexpectedly,in spring,there were more sand and dust occurrences in northern China.展开更多
The work discusses the temperature and precipitation fluctuation of Madinah-Al-Munawara, Saudi Arabia for a time period of 1959-2011. This is a city in the Hejaz region of western Saudi Arabia, the capital of Al Madin...The work discusses the temperature and precipitation fluctuation of Madinah-Al-Munawara, Saudi Arabia for a time period of 1959-2011. This is a city in the Hejaz region of western Saudi Arabia, the capital of Al Madinah Province and important religious place. For many years now, Royal Kingdom of Saudi Arabia is active on national as well as international levels to adopt a more suitable policy for the study of climate changes and reviews it periodically as per country economic desires. The main sectors that affect the temperature and precipitation fluctuations in Saudi Arabia are surface water, coastal management, overgrazing, forestry, livestock, drought, desertification, industrialization, landuse change, tourism, and aridity etc. The paper analyzes the temperature and precipitation fluctuations of Madinah-Al-Munawara in terms of general climatology, climate fluctuation/variation, seasonal distribution and extreme weather events. The mean monthly temperature of the city recorded during 1959-2011 is 28°C having mean maximum temperature of 34°C and mean minimum of 21°C. The mean monthly temperature of the city shows an increase of 1.7°C having 1.2°C increase in maximum temperature and decrease of -1.9°C in minimum temperature. Generally, there is a rise and fall in the temperature condition and shows irregular pattern throughout the period. The total precipitation of the city is 36 millimeters;having a decrease of -0.3 millimeters but in general the trend of precipitation at Madinah-Al-Munawara shows an increasing trend throughout the period. April and November are the wettest, while June, August, September and October are the hottest months of the city. The area is characterized by two main seasons that is winter (5 months) and summer (7 months), which can further be sub-divided into four rainy seasons namely winter, post-winter, summer, and post-summer seasons.展开更多
The distribution transformer is the mainstay of the power system.Its internal temperature study is desirable for its safe operation in the power system.The purpose of the present study is to determine direct comprehen...The distribution transformer is the mainstay of the power system.Its internal temperature study is desirable for its safe operation in the power system.The purpose of the present study is to determine direct comprehensive thermal distribution in the distribution transformers for different loading conditions.To achieve this goal,the temperature distribution in the oil,core,and windings are studied at each loading.An experimental study is performed with a 10/0.38 kV,10 kVA oil–immersed transformer equipped with forty–two PT100 sensors(PTs)for temperature measurement installed inside during its manufacturing process.All possible locations for the hottest spot temperature(HST)are considered that made by finite element analysis(FEA)simulation and losses calculations.A resistive load is made to achieve 80%to 120%loading of the test transformer for this experiment.Working temperature is measured in each part of the transformer at all provided loading conditions.It is observed that temperature varies with loading throughout the transformer,and a detailed map of temperature is obtained in the whole test transformer.From these results,the HST stays in the critical section of the primary winding at all loading conditions.This work is helpful to understand the complete internal temperature layout and the location of the HST in distribution transformers.展开更多
基金supported by the National Natural Science Foundation of China[grant number 41405069],[grant number91537214],[grant number 41605063]the Key Foundation of the Education Department of Sichuan Province[grant number16ZA0203]the Scientific Research Foundation of Chengdu University of Information Technology[grant number KYTZ201517],[grant number J201516],[grant number J201518]
文摘Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it is important to investigate the ranking of hottest years. In this study, the Wilcoxon signed-ranktest and Monte Carlo simulation are used to estimate the ranking of the hottest years for theTibetan Plateau （TP） in recent decades, and the uncertainty in the ranking.The Wilcoxon signed-rank test shows that the top 10 hottest years on record over the TP mainly occur after 1998. The top three hottest years are ranked as 2006, 2009, and 2010, but there is almost no significant difference between them. When both sampling and observational errors are considered, only five years have a non-zero probability of being the hottest year, with the three highest probabilities being for the years 2006 （-47.231%）, 2009 （-40.390%）, and 2010 （-12.376%）. Similarly, with respect to a given year that is among the 10 hottest years, our results show that all the years among the ranks of 1-10 resulting from the Wilcoxon signed-rank test have probabilities above 10%, while the years 2001 and 2012 have probabilities of 3% and 4%.
文摘为分析高压电容式油气套管内部暂态温度与其短时载流能力的关系,提出了适用于高压油气套管结构的集总RC热网络模型。该模型计及传导、对流和辐射3种传热方式,考虑了材料性能随温度的变化关系,并基于MATLAB/Simulink实现了热网络拓扑结构。以550 k V油/SF6套管为例,暂态温度热网络计算结果与实际温升试验结果吻合较好,证明了集总RC热网络的有效性和实用性,通过阶梯载荷曲线拟合昼夜周期变化负载,并结合热网络确定了油气套管最热点温度的周期暂态变化规律。研究表明油气套管最热点位于中心导杆与绝缘芯子界面处,且各载荷步下套管暂态温度值与稳态温度值存在较大差异。将集总RC热网络方法应用于油气套管暂态温度计算,补充了仅考虑稳态额定运行条件的传统套管设计方法,对分析油气套管运行中的短时载流能力有一定理论指导作用。
基金supported by the National Key Research and Development Program of China[grant numbers 2023YFC3206001 and 2018YFC150706]the China Meteorological Administration Innovation Development Program[grant number CXFZ2024J071]the National Natural Science Foundation of China[grant numbers U2342209 and 42175078].
文摘China witnessed a warm and dry climate in 2023.The annual surface air temperature reached a new high of 10.71℃,with the hottest autumn and the second hottest summer since 1961.Meanwhile,the annual precipitation was the second lowest since 2012,at 615.0 mm.Precipitation was less than normal from winter to summer,but more in autumn.Consistent with the annual condition,precipitation in the flood season from May to September was also the second lowest since 2012,which was 4.3%less than normal,with the anomalies in the central and eastern parts of China being higher in central areas and lower in the north and south.On the contrary,the West China Autumn Rain brought much more rainfall than normal,with an earlier start and later end.Although there was less annual precipitation in 2023,China suffered seriously from heavy precipitation events and floods.In particular,from the end of July to the beginning of August,a rare,extremely strong rainstorm caused by Typhoon Dussuri hit Beijing,Tianjin,and Hebei,causing an abrupt alteration from drought to flood conditions in North China.By contrast,Southwest China experienced continuous drought from the previous autumn to current spring.In early summer,North China and the Huanghuai region experienced the strongest high-temperature process since 1961.Nevertheless,there were more cold-air processes than normal impacting China,with the most severe of the year occurring in mid-January.Unexpectedly,in spring,there were more sand and dust occurrences in northern China.
文摘The work discusses the temperature and precipitation fluctuation of Madinah-Al-Munawara, Saudi Arabia for a time period of 1959-2011. This is a city in the Hejaz region of western Saudi Arabia, the capital of Al Madinah Province and important religious place. For many years now, Royal Kingdom of Saudi Arabia is active on national as well as international levels to adopt a more suitable policy for the study of climate changes and reviews it periodically as per country economic desires. The main sectors that affect the temperature and precipitation fluctuations in Saudi Arabia are surface water, coastal management, overgrazing, forestry, livestock, drought, desertification, industrialization, landuse change, tourism, and aridity etc. The paper analyzes the temperature and precipitation fluctuations of Madinah-Al-Munawara in terms of general climatology, climate fluctuation/variation, seasonal distribution and extreme weather events. The mean monthly temperature of the city recorded during 1959-2011 is 28°C having mean maximum temperature of 34°C and mean minimum of 21°C. The mean monthly temperature of the city shows an increase of 1.7°C having 1.2°C increase in maximum temperature and decrease of -1.9°C in minimum temperature. Generally, there is a rise and fall in the temperature condition and shows irregular pattern throughout the period. The total precipitation of the city is 36 millimeters;having a decrease of -0.3 millimeters but in general the trend of precipitation at Madinah-Al-Munawara shows an increasing trend throughout the period. April and November are the wettest, while June, August, September and October are the hottest months of the city. The area is characterized by two main seasons that is winter (5 months) and summer (7 months), which can further be sub-divided into four rainy seasons namely winter, post-winter, summer, and post-summer seasons.
文摘The distribution transformer is the mainstay of the power system.Its internal temperature study is desirable for its safe operation in the power system.The purpose of the present study is to determine direct comprehensive thermal distribution in the distribution transformers for different loading conditions.To achieve this goal,the temperature distribution in the oil,core,and windings are studied at each loading.An experimental study is performed with a 10/0.38 kV,10 kVA oil–immersed transformer equipped with forty–two PT100 sensors(PTs)for temperature measurement installed inside during its manufacturing process.All possible locations for the hottest spot temperature(HST)are considered that made by finite element analysis(FEA)simulation and losses calculations.A resistive load is made to achieve 80%to 120%loading of the test transformer for this experiment.Working temperature is measured in each part of the transformer at all provided loading conditions.It is observed that temperature varies with loading throughout the transformer,and a detailed map of temperature is obtained in the whole test transformer.From these results,the HST stays in the critical section of the primary winding at all loading conditions.This work is helpful to understand the complete internal temperature layout and the location of the HST in distribution transformers.
