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Assessment of diurnal variation of summer precipitation over the Qilian Mountains based on an hourly merged dataset from 2008 to 2014

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Journal of Geographical Sciences 2017年第3期27卷 326-336页

作者： LIU Xuemei zhang mingjun WANG Shengjie WANG Jie ZHAO Peipei ZHOU Panpan College of Geography and Environmental Science Northwest Normal University Lanzhou 730070 China

To investigate the diurnal variation of summer precipitation in the Qilian Mountains in the northeast Tibetan Plateau, the hourly precipitation amount for this region during the summers of 2008-2014 are analyzed using an hourly merged precipitation product at 0.1°×0.1 ° resolution. The main results are as follows. （1） The spatial distribution and temporal variation of mean hourly precipitation amount and frequency are generally similar and hourly precipitations in the eastern and middle portions are larger and more frequent than that in the western portion. The high value area of precipitation intensity is obviously different from that of precipitation amount and frequency. （2） The spatial distribution of daytime precipitation is generally similar to that of nighttime precipitation, and the daytime precipitation is heavier than the nighttime precipitation. （3） The change rate of precipitation has a maximum at 20：00 Beijing time, and a minimum at 12：00. The hourly precipitation amount significantly correlated with frequency, especially for the middle and eastern portions.

关键词： Qilian Mountains summer precipitation diurnal variation

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水下双目视觉系统中的目标分割和目标定位

华中科技大学学报（自然科学版） 2017年第12期45卷 53-59页

作者：李煊张铭钧哈尔滨工程大学机电工程学院黑龙江哈尔滨150001

针对典型灰度化和阈值方法用于水下目标分割时存在的目标分割不完整等问题,提出了基于灰度对比度增强的两步目标分割方法:第一步基于彩色矢量阈值进行目标粗分割;第二步分析局部对比度和区域内均匀性,动态确定不同通道的权值和反向处理... 详细信息

针对典型灰度化和阈值方法用于水下目标分割时存在的目标分割不完整等问题,提出了基于灰度对比度增强的两步目标分割方法:第一步基于彩色矢量阈值进行目标粗分割;第二步分析局部对比度和区域内均匀性,动态确定不同通道的权值和反向处理,进而增强灰度对比度,完成目标精分割.针对典型标定、立体匹配和目标位置测量方法不适用于本研究环境的问题,提出了基于目标尺寸估计的目标定位方法,首先完成在线外参标定和目标圆心匹配,然后利用双目位置测量数据估计目标的尺寸,最后采用单目位置测量得到定位数据.结果表明:该分割方法能够准确分割目标,分割准确率和错分类比率均优于典型方法,定位方法能够得到目标三维位置数据,研制的双目视觉系统能够有效配合水下运载器-机械手系统完成自主作业任务.

关键词：目标分割目标定位灰度对比度增强目标尺寸估计水下双目视觉系统自主作业

Changes in daily extreme precipitation events in South China from 1961 to 2011

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Journal of Geographical Sciences 2015年第1期25卷 58-68页

作者： REN Zhengguo zhang mingjun WANG Shengjie QIANG Fang ZHU Xiaofan DONG Lei College of Geography and Environmental Science Northwest Normal University Lanzhou 730070 China

Based on the daily precipitation from a 0.5°×0.5° gridded dataset and meteorological stations during 1961-2011 released by National Meteorological Information Center, the reliability of this gridded precipitation dataset in South China was evaluated. Five precipitation indices recommended by the World Meteorological Organization （WMO） were selected to investigate the changes in precipitation extremes of South China. The results indicated that the bias between gridded data interpolated to given stations and the corresponding observed data is limited, and the proportion of the number of stations with bias between -10% and 0 is 50.64%. The correlation coefficients between gridded data and observed data are generally above 0.80 in most parts. The average of precipitation indices shows a significant spatial difference with drier northwest section and wetter southeast section. The trend magnitudes of the maximum 5-day precipitation （RX5day）, very wet day precipitation （R95）, very heavy precipitation days （R20mm） and simple daily intensity index （SDII） are 0.17 mm·a^-1, 1.14 mm·a^-1, 0.02 d·a^-1 and 0.01 mm·d^-1·a^-1, respectively, while consecutive wet days （CWD） decrease by -0.05 d·a^-1 during 1961-2011. There is spatial disparity in trend magnitudes of precipitation indices, and approximate 60.85%, 75.32% and 75.74% of the grid boxes show increasing trends for RX5day, SDII and R95, respectively. There are high correlations between precipitation indices and total precipitation, which is statistically significant at the 0.01 level.

关键词： precipitation extremes gridded data South China

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自主式水下机器人自适应区域跟踪控制

机械工程学报 2014年第19期50卷 50-57页

作者：张铭钧褚振忠哈尔滨工程大学机电工程学院哈尔滨150001

研究自主式水下机器人的区域跟踪控制问题,提出一种基于PD神经滑模的自适应区域跟踪控制方法。针对自主式水下机器人自适应控制器中仅在线调整网络权值的径向基函数神经网络存在收敛性能差的问题,给出同时对径向基函数神经网络权值、径... 详细信息

研究自主式水下机器人的区域跟踪控制问题,提出一种基于PD神经滑模的自适应区域跟踪控制方法。针对自主式水下机器人自适应控制器中仅在线调整网络权值的径向基函数神经网络存在收敛性能差的问题,给出同时对径向基函数神经网络权值、径向基函数中心与方差进行自适应调整的方法,使径向基函数神经网络无须离线选取径向基函数中心与方差,即可进行在线自适应学习。考虑到控制器中滑模控制项易引起系统抖振的问题,提出一种基于指数函数的滑模切换增益调节方法,使滑模切换增益能够依据跟踪误差实时调节以降低系统抖振。基于Lyapunov理论对所提自适应区域跟踪控制方法的稳定性进行分析。通过自主式水下机器人的仿真试验与水池试验验证所提方法的有效性。

关键词：水下机器人区域跟踪控制滑模控制神经网络控制

Glacier area variation and climate change in the Chinese Tianshan Mountains since 1960

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Journal of Geographical Sciences 2011年第2期21卷 263-273页

作者： WANG Shengjie zhang mingjun LI Zhongqin WANG Feiteng LI Huilin LI Yaju HUANG Xiaoyan College of Geography and Environment Sciences Northwest Normal University Lanzhou 730070 China State Key Laboratory of Cryospheric Sciences / Tianshan Glaciological Station Cold and Arid Regions Environmental and Engineering Research Institute CAS Lanzhou 730000 China

Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total area of the glaciers has been reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier area variations of 10 drainage basins separated by the Glacier Inventory of China （GIC）. The annual percentage of area changes （APAC） of glaciers in the Chinese Tianshan Mountains is 0.31% after the standardization of the study period. The APAC varies widely for different drainage basins, but the glaciers are in a state of rapid retreat, generally. According to the 14 meteorological sta- tions in the Chinese Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 at a rate of 0.34℃·（10a）^-1 and 11 mm·（10a）^-1, respectively. The temperature in the dry seasons （from November to March） increases rapidly at a rate of 0.46℃·（10a）^-1, but the precipitation grows slowly at 2.3 mm·（10a）^-1. While the temperature in the wet seasons （from April to October） grows at a rate of 0.25℃·（10a）^-1, but the precipitation increases at 8.7 mm·（10a）^-1, The annual and seasonal climatic trends accelerate the retreat of glaciers.

关键词： Chinese Tianshan Mountains glacier area climate change temperature precipitation

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缓冲区溢出静态分析中的指针分析算法

计算机工程 2005年第18期31卷 41-43,107页

作者：张明军罗军国防科学技术大学计算机学院长沙410073

提出一个扩展的流不敏感指针分析算法,主要用于缓冲区溢出静态分析,该算法把程序控制流图(CFG)转换为静态单指派(SSA),然后循环调用一个流不敏感指针分析,生成每个指针变量精确的指向集,更新指针变量的定义-引用链中约束信息。在LLVM编... 详细信息

提出一个扩展的流不敏感指针分析算法,主要用于缓冲区溢出静态分析,该算法把程序控制流图(CFG)转换为静态单指派(SSA),然后循环调用一个流不敏感指针分析,生成每个指针变量精确的指向集,更新指针变量的定义-引用链中约束信息。在LLVM编译系统下实现了该算法,实验表明其精度和流敏感的指针分析算法相当,但效率高于流敏感指针分析算法,时间复杂度低于流敏感指针分析算法。

关键词：缓冲区溢出指针分析静态单指派定义-引用链

Changes in air temperature over China in response to the recent global warming hiatus

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Journal of Geographical Sciences 2019年第4期29卷 496-516页

作者： DU Qinqin zhang mingjun WANG Shengjie CHE Cunwei MA Rong MA Zhuanzhuan College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China

The 1998–2012 global warming hiatus has aroused great public interest over the past several years. Based on the air temperature measurements from 622 meteorological stations in China, the temperature response to the global warming hiatus was analyzed at national and regional scales. We found that air temperature changed –0.221℃/10 a during 1998–2012, which was lower than the long-term trend for 1960–1998 by 0.427℃/10 a. Therefore, the warming hiatus in China was more pronounced than the global mean. Winter played a dominant role in the nationwide warming hiatus, contributing 74.13%, while summer contributed the least among the four seasons. Furthermore, the warming hiatus was spatial heterogeneous across different climate conditions in China. Comparing the three geographic zones, the monsoon region of eastern China, arid region of northwestern China, and high frigid region of the Tibetan Plateau, there was significant cooling in eastern and northwestern China. In eastern China, which contributed 53.79%, the trend magnitudes were 0.896℃/10 a in winter and 0.134℃/10 a in summer. In the Tibetan Plateau, air temperature increased by 0.204℃/10 a, indicating a lack of a significant warming hiatus. More broadly, the warming hiatus in China may have been associated with the negative phase of PDO and reduction in sunspot numbers and total solar radiation. Finally, although a warming hiatus occurred in China from 1998 to 2012, air temperature rapidly increased after 2012 and will likely to continuously warm in the next few years.

关键词： global warming hiatus three geographic zones temperature China

Increasing free-air 0℃ isotherm height in Southwest China from 1960 to 2010

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Journal of Geographical Sciences 2014年第5期24卷 833-844页

作者： zhang mingjun DONG Lei WANG Shengjie ZHAO Aifang QIANG Fang SUN Meiping WANG Qiong College of Geography and Environmental Science Northwest Normal University Lanzhou 730070 China

Based on the radiosonde data observed at 14 stations in Southwest China from 1960 to 2010, as well as the corresponding surface air temperature, the long-term change of free-air 0℃ isotherm height in Southwest China and the relationships between surface air temperature and 0℃ isotherm height are discussed. The results indicated that the spatial distribution of 0℃ isotherm height is generally related with latitude, but the huge massif or plateau may complicate the latitude pattern. The two main regimes influencing the spatial patterns of 0℃ isotherm height in Southwest China are latitude and huge massif. The annual 0℃ isotherm height has increased by 35 m per decade in the recent decades, which is statistically significant at the 0.001 level. Generally, the increasing trend can be examined for each seasonal series, especially in winter （53 m per decade）. The diversity of trend magnitudes for annual and seasonal series can also be detected at a spatial view, but generally 0℃ isotherm height correlated well with surface air temperature.

关键词： Southwest China 0℃ isotherm height global warming radiosonde data

Extreme drought changes in Southwest China from 1960 to 2009

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Journal of Geographical Sciences 2013年第1期23卷 3-16页

作者： zhang mingjun HE Jinyun WANG Baolong WANG Shengjie LI Shanshan LIU Wenli MA Xuening College of Geography and Environment Sciences Northwest Normal University Lanzhou 730070 China

Based on the daily data of temperature and precipitation of 108 meteorological stations in Southwest China from 1960 to 2009, we calculate the monthly and yearly surface humid indexes, as well as the extreme drought frequency. According to the data, the temporal and spatial characteristics of the extreme drought frequency in inter-annual, inter-decadal, summer monsoon period and winter monsoon period are analyzed. The results are indicated as follows. （1） In general, the southwestern Sichuan Basin, southern Hengduan Mountains, southern coast of Guangxi and northern Guizhou are the areas where the extreme drought frequency has significantly increased in the past 50 years. As for the decadal change, from the 1960s to the 1980s the extreme drought frequency has presented a decreasing trend, while the 1990s is the wettest decade and the whole area is turning wet. In the 2000s, the extreme drought frequency rises quickly, but the regional differences reduce. （2） During summer monsoon period, the extreme drought frequency is growing, which generally occurs in the high mountains around the Sichuan Basin, most parts of Guangxi and ＂the broom-shaped mountains＂ in Yunnan. It is distinct that the altitude has impacts on the ex- treme drought frequency; during winter monsoon period, the area is relatively wet and the extreme drought frequency is decreasing. （3） During summer monsoon period, the abrupt change is observed in 2003, whereas the abrupt change during winter monsoon period is in 1989. The annual extreme drought frequency variation is a superposition of abrupt changes during summer monsoon and winter monsoon periods. The departure sequence vibration of annual extreme drought frequency is quasi-5 years and quasi-12 years.

关键词： Southwest China extreme drought summer monsoon winter monsoon