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Prediction of permafrost changes in Northeastern China under a changing climate

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Science China Earth Sciences 2011年第6期54卷 924-935页

作者： WEI Zhi jiN HuiJun ZHANG jianMing YU ShaoPeng HAN XuJun ji yanjun HE RuiXia CHANG XiaoLi State Key Laboralory of Frozen Soils Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Northwest University for Nationalities Lanzhou 730030 China Baiyin Hydraulic Engineering Designing Institute Baiyin 730900 China Laboratory of Remote Sensing and Geospatial Science Cold and Arid Regions Environmental and Engineering Chinese Academy of Sciences Lanzhou 730000 China Gansu Electric Power Design Institute Lanzhou 730050 China

Northeastern China has the second largest expanse of permafrost in China,primarily known as Xing'an-Baikal *** on the southeastern edges of the Eurasian cryolithozone,the permafrost is thermally unstable and ecologically sensitive to external *** combined impacts of climatic,environmental,and anthropogenic changes cause 3-dimensional degradation of the *** predict these changes on the southern limit and ground temperature of permafrost in Northeastern China,an equivalent latitude model (ELM) for the mean annual ground surface temperature (MAGSTs) was proposed,and further improved to take into account of the influences of vegetation and snow-cover based on observational data and using the SHAW *** the finite element method and assuming a climate warming rate of 0.048°C a-1,the ELM was combined with the unsteady-state heat conduction model to simulate permafrost temperatures at present,and to predict those after 50 and 100 *** results indicate that at present,sporadic permafrost occurs in the zones with MAGSTs of 1.5°C or colder,and there would still be a significant presence of permafrost in the zones with the present MAGSTs of 0.5°C or colder after 50 a,and in those of-0.5°C or colder after 100 ***,the total areal extent of permafrost would decrease from 2.57×105 km2 at present to 1.84×105 km2 after 50 a and to 1.29×105 km2 after 100 a,i.e.,a reduction of 28.4% and 49.8% in the permafrost area,*** the permafrost would degrade more substantially in the east than in the *** warming and thinning of permafrost would also *** area of stable permafrost (mean annual ground temperature,or MAGT≤-1.0°C) would decrease from present 1.07×105 to 8.8×104 km2 after 50 a,and further decrease to 5.6×104 km2 after 100 *** a result,the unstable permafrost and seasonally frozen ground would expand,and the southern limit of permafrost would shift significantly *** changes in the permafrost env

关键词： permafrost Northeastern China climate change equivalent latitude model (ELM) prediction

Direct incorporation of paraffin wax as phase change material into mass concrete for temperature control: mechanical and thermal properties

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Research in Cold and Arid Regions 2021年第1期13卷 30-42页

作者： Tao Luo JuanJuan Ma Fang Liu MingYi Zhang ChaoWei Sun yanjun ji XiaoSa Yuan Shaanxi Key Laboratory of Safety and Durability of Concrete Structures Xijing UniversityXi'anShaanxi 710123China State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control *** mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending *** more Paraffin wax incorporated,the greater loss of the compressive strength and bending *** on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature *** the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,*** the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,*** adiabatic temperature rise is found to decrease with an increasing Paraffin wax *** both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.

关键词： phase change material Paraffin wax temperature control mechanical properties thermal properties mass concrete

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基于最小熵解卷积的汽车点焊质量超声评价

焊接学报 2018年第8期39卷 59-65,132页

作者：何智成汲彦军成艾国湖南大学汽车车身先进设计制造国家重点实验室长沙410082

利用超声信号的时域信息,可以对焊点质量进行评价.白车身焊点超声检测的过程中,由于噪声信号的模糊作用,反映焊点质量的有用信息被掩盖,导致焊点质量评价结果不准确.超声探头接收到的超声信号可视为原始超声信号与噪声信号两种信号的叠... 详细信息

利用超声信号的时域信息,可以对焊点质量进行评价.白车身焊点超声检测的过程中,由于噪声信号的模糊作用,反映焊点质量的有用信息被掩盖,导致焊点质量评价结果不准确.超声探头接收到的超声信号可视为原始超声信号与噪声信号两种信号的叠加,基于超声信号的卷积模型及稀疏特性,可利用最小熵盲反卷积(MED)对超声信号进行解卷积处理,分离重叠的焊点超声信号,恢复信号反射系数,获取准确的回波个数.通过仿真与试验,结果表明,最小熵解卷积对焊点重叠超声信号分离的有效性.

关键词：超声检测质量评价最小熵解卷积重叠回波

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汽车覆盖件抗凹性实验评估及测量装置设计

汽车工程 2016年第11期38卷 1402-1406页

作者：成艾国蒋风光汲彦军刘斌湖南大学汽车车身先进设计制造国家重点实验室长沙410082

对汽车覆盖件抗凹性的评估指标和实验方法进行了介绍,并综合运用机械装置和Lab VIEW程序,设计出一套抗凹性测量装置。该装置简单、实用,可供机械设计师参考。

关键词：汽车覆盖件抗凹性实验评估测量装置

Underwater wireless optical NOMA communication experiment system exploiting GaN-based micro-LED array grouping

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Chinese Optics Letters 2024年第3期22卷 1-6页

作者：梁彦军殷洪玺黄安季秀阳王建英 School of Information and Communication Engineering Dalian University of TechnologyDalian 116024China

This paper has proposed an experimental system for non-orthogonal multiple access(NOMA)wireless optical communication in challenging underwater turbulent environments,employing the gallium nitride(GaN)-based micro-LED *** design of the GaN-based micro-LED array enables the independent transmission of signals from distinct data streams within the NOMA framework,facilitating direct optical power-domain superposition of NOMA *** experimental setup involves emulating oceanic turbulence channels,characterized by varying the level of scintillation intensity,to thoroughly investigate the bit error rate(BER)*** outcomes unequivocally demonstrate the superiority of our proposed NOMA scheme,as compared to conventional circuit-driven optical NOMA systems utilizing fixed LED array grouping,particularly in the presence of turbulent underwater *** proposed NOMA scheme exhibits consistently superior BER performance and maintains excellent linearity at the lower frequencies while effectively mitigating signal distortion at the higher frequencies.

关键词： optical non-orthogonal multiple access gallium nitride-based micro-LED array oceanic turbulence channels bit error rate

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超声波检测焊点质量的建模方法及应用分析

中国机械工程 2018年第3期29卷 359-365页

作者：何智成汲彦军成艾国何道聪湖南大学汽车车身先进设计制造国家重点实验室长沙410082 上汽通用五菱汽车股份有限公司柳州545027

介绍了两层板焊接时焊点的有限元建模方法:通过金相实验得到焊点尺寸参数,利用超声检测的回波衰减理论及超声波传播衰减信号得到焊点阻尼系数。首先建立了材料为BLD的两层板多类型焊点有限元模型,然后通过与设备检测对比的方法验证了模... 详细信息

介绍了两层板焊接时焊点的有限元建模方法:通过金相实验得到焊点尺寸参数,利用超声检测的回波衰减理论及超声波传播衰减信号得到焊点阻尼系数。首先建立了材料为BLD的两层板多类型焊点有限元模型,然后通过与设备检测对比的方法验证了模型的准确性,最后研究了探头在曲面检测工况下角度定位的灵敏度问题,并通过实验进行了验证,实验结果表明:对曲面焊点质量进行检测时,探头角度偏离法线10°范围内,检测结果受到的影响很小。

关键词：超声波焊点模型有限元建模曲面检测

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基于互相关的气泡速度的测量方法研究

光子学报 2005年第8期34卷 1253-1256页

作者：陈敏何俊华纪延俊阎亚东陈良益中国科学院西安光学精密机械研究所山东滨州学院山东256604

通过对比互相关技术和多普勒技术的差别,从一个新的角度把互相关技术应用于尾流测速的研究中.实验中利用高速CCD相机拍摄模拟尾流图像.利用快速傅里叶变换实现互相关算法,为提高计算准确度采用高斯曲线拟合互相关函数的峰值并给出拟合公... 详细信息

通过对比互相关技术和多普勒技术的差别,从一个新的角度把互相关技术应用于尾流测速的研究中.实验中利用高速CCD相机拍摄模拟尾流图像.利用快速傅里叶变换实现互相关算法,为提高计算准确度采用高斯曲线拟合互相关函数的峰值并给出拟合公式,得到了亚像素级的运动速度.为标定互相关算法的准确度,文中采用图像平移的方法验证算法的可行性和可靠性.最后把算法应用于模拟尾流的实验中.该方法有望在舰船尾流速度信息的实时获取上起到重要的应用价值.

关键词：速度互相关尾流气泡

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上海市嘉定区大气降水的化学特征及来源解析

环境与发展 2023年第1期35卷 75-82页

作者：季彦鋆上海市嘉定区环境监测站上海201822

以2011-2020年上海市嘉定区降雨监测点的816组降水数据,分析了10年期间该地区大气降水的酸化程度、化学组分及其来源与相对贡献。结果表明:在此期间年均降水pH为4.70~5.73,酸雨频率87.84%~40.85%,降水电导率为3.51~1.20mS/m,均呈现出好... 详细信息

以2011-2020年上海市嘉定区降雨监测点的816组降水数据,分析了10年期间该地区大气降水的酸化程度、化学组分及其来源与相对贡献。结果表明:在此期间年均降水pH为4.70~5.73,酸雨频率87.84%~40.85%,降水电导率为3.51~1.20mS/m,均呈现出好转的趋势。2012年及以后,嘉定区降水以轻度污染为主,2019、2020年清洁降水达到25%以上。大气降水中水溶性离子平均当量浓度大小为NH^(+)_(4)>NO_(3)^(-)>SO_(4)^(2+)>Cl^(-)>Ca^(2+)>Na^(+)>F^(-)>K^(+)>Mg^(2+),SO_(4)^(2-)/NO_(3)^(-)值出现明显降低,降水类型由硫酸型转变为硫酸+硝酸混合型。K^(+)和Ca^(2+)主要来自于地表源和人为源;SO_(4)^(2+)和NO_(3)^(-)主要为人为活动造成的;Cl^(-)的主要来自海洋源及人为源。综合数据表明,近10年嘉定区大气降水污染程度呈现好转态势,各级政府出台的环境污染控制举措效果显著。

关键词：上海市嘉定区降水酸雨化学特性来源解析

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基于盲反卷积和参数化模型的超声参数估计

仪器仪表学报 2015年第11期36卷 2611-2616页

作者：聂昕郭志福何智成成艾国汲彦军湖南大学汽车车身先进设计制造国家重点实验室长沙410082

在超声检测中,往往需要获得传播时间(TOF)、回波个数、中心频率、幅值等全面的信息,来综合评判缺陷的位置、大小和类型。通过建立多回波的卷积模型和参数化模型,给出一种结合最小熵盲反卷积(MED)和期望值最大(EM)算法思想的超声回波参... 详细信息

在超声检测中,往往需要获得传播时间(TOF)、回波个数、中心频率、幅值等全面的信息,来综合评判缺陷的位置、大小和类型。通过建立多回波的卷积模型和参数化模型,给出一种结合最小熵盲反卷积(MED)和期望值最大(EM)算法思想的超声回波参数估计方法。首先基于卷积模型,采用最小熵反卷积,实现了重叠多回波信号的有效分离;再基于参数化模型和所获取的回波个数,给出了基于期望值最大算法思想的参数估计算法;最终实现了重叠多回波超声信号TOF、回波个数、中心频率、幅值等参数的精确估计。仿真和实验验证了该方法的有效性和优点。

关键词：最小熵盲反卷积 EM算法参数化模型参数估计超声回波