检索结果-南通市图书馆

High-Order Statistics of Temperature Fluctuations in an Unstable Atmospheric Surface Layer over Grassland

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2018年第10期35卷 1265-1276页

作者： Rui LYU Fei HU Lei LIU Jingjing XU xueling cheng State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Skewness(S) and kurtosis(K) of temperature in the surface layer over a grassland are investigated under unstable thermal stratifications. We find that both skewness and kurtosis generally obey Monin–Obukhov similarity theory and tend to be constant values(1.5 and 5.3, respectively) when the stability parameter z/L <-2. Quantitative formulas of the similarity functions are proposed. The temperature probability density function(PDF) is close to Gaussian in near neutral stratification and non-Gaussian in unstable stratification. The influence of coherent motions on the PDF behavior is analyzed using the quadrant analysis technique. It shows that PDF behaviors are controlled by ejections and sweeps. The results also indicate that the PDF type of the ejections always follows a Gaussian distribution, while the PDF of the sweeps changes with stability.

关键词： temperature fluctuations Monin–Obukhov similarity theory skewness kurtosis

在线全文

学校读者我要写书评

暂无评论

不同蒸煮方式对燕麦方便粥品质的影响

食品与发酵工业 2025年第1期51卷 231-236页

作者：郭恬静梁月光程雪玲陈琼玲陈振家顾丰颖王愈山西农业大学食品科学与工程学院山西太谷030801 山西省果蔬贮藏保鲜与加工技术创新中心山西太谷030801 中国农业科学院农产品加工研究所北京100193

燕麦富含多酚类功能活性成分,可用于制作方便粥,但目前市场上的燕麦方便粥多以挤压膨化处理为主,该试验采用常压蒸煮、高压蒸煮和微波蒸煮3种不同方式制作燕麦方便粥,研究3种处理方式对燕麦方便粥的色泽、质构特性、微观结构、多酚含量... 详细信息

燕麦富含多酚类功能活性成分,可用于制作方便粥,但目前市场上的燕麦方便粥多以挤压膨化处理为主,该试验采用常压蒸煮、高压蒸煮和微波蒸煮3种不同方式制作燕麦方便粥,研究3种处理方式对燕麦方便粥的色泽、质构特性、微观结构、多酚含量、感官品质的影响,旨在为人们提供一种口感良好、功能活性成分较高的燕麦方便粥。结果表明,3种蒸煮方式均显著改变了方便粥的色泽;高压蒸煮可以显著降低燕麦方便粥的硬度、胶黏性、咀嚼性,分别为14.67 N、5.2 N、3.45 mJ,但弹性低于其他两种蒸煮方式;3种方式处理的方便粥微观结构均有所不同,但淀粉颗粒都变得疏松,有利于复水;微波蒸煮和高压蒸煮总酚含量保留较好,分别为63.93和61.88μg/g;3种蒸煮方式的感官评分依次为高压蒸煮>常压蒸煮>微波蒸煮。由此可见,经高压蒸煮后的燕麦方便粥具有较高的质构特性和感官品质,能够较好的保留燕麦的色泽及多酚含量,因此高压蒸煮是一种较好的制作燕麦方便粥的方式。

关键词：燕麦方便粥蒸煮方式品质分析多酚

Simulation of wind gust structure in the atmospheric boundary layer with Lattice Boltzmann Method

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2012年第10期57卷 1196-1203页

作者： cheng xueling HU Fei ZENG QingCun State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy ofSciences Beijing 100029 China

Cold fronts occur in northern East Asia during winter and *** cold frontal passage,airflow is downward and accompa-nying strong winds fluctuate significantly;this is termed wind *** of observation data shows that wind gust structure has coherent *** is important for entrainment of spring dust storms into the upper boundary layer,where they are transported great *** Lattice Boltzmann Method(LBM) is a computational fluid technique based on the Boltzmann transport *** LBM has been used to study complex motion such as turbulence,because it describes motion at the micro *** this paper,Large eddy simulation is introduced in the LBM,enabling simulation of turbulent flow in the atmospheric boundary *** formation and development of wind gusts are simulated,and a coherent structure with a combination of wave and vortex is *** explains the mechanism of soil erosion and sand entrainment by the coherent structure of wind gusts.

关键词：格子Boltzmann方法大气边界层大涡模拟相干结构阵风 LBM 观测数据流体技术

同方期刊数据库

Stochastic method to determine the scale and anomalous diffusion of gusts in a windy atmospheric boundary layer

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第2期59卷 4890-4898页

作者： xueling cheng Fei Hu Qingcun Zeng State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences

In the atmospheric boundary layer, especially during strong wind period, the coherent structures are obvious and related to the direct interaction of the air masses with the ground. In this paper, we used the observation data during dust weather in Northwest Gansu to study the coherent structure and their ‘‘anomalous diffusion''. The structures in the atmospheric boundary layer included turbulent fluctuations and gusty wind disturbances, and could be denoted as ‘‘critical events' '. Their fractal dimensions were expressed by the complex index l of waiting times. Although the complex index can indicate the ability of the system to generate coherent structures, it has a strong dependence on the threshold marking the‘‘critical events' '. Hence, the continuous time random walk method was used to analyze the coherent structures. The scaling law of anomalous diffusion of coherent structures was obtained, and the diffusion scaling exponent H that indicated the ability of diffusion of different structures was analyzed. The exponents changed with structure scales which were affected by velocities and heights. At small scales, it was almost isotropic, and at large scales, the coherent structures were obvious and the diffusion was anomalous.

关键词：大气边界层结构反常扩散随机游动阵风相干结构扩散能力相互作用观测数据

同方期刊数据库

Advances in coastal ocean boundary layer detection technology and equipment in China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2023年第1期123卷 156-168页

作者： Haitao Zheng Youwen Sun Tao Luo xueling cheng Shiyong Shao Shouyin Zheng Bangyi Tao Bin Chen Qianguang Tu Kan Huang Bingbing Wang Mian Wang Xiaoquan Song Tianshu Zhang Yin cheng Jianguo Liu Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsHFIPSChinese Academy of SciencesHefei 230031China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Key Laboratory of Atmospheric Optics Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China Advanced Laser Technology Laboratory of Anhui Province Hefei 230031China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China College of Earth Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China School of Surveying and Municipal Engineering Zhejiang University of Water Resources and Electric PowerHangzhou 310018China Center for Atmospheric Chemistry Study Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3)Department of Environmental Science and EngineeringFudan UniversityShanghai 200433China State Key Laboratory of Marine Environmental Science College of Ocean and Earth SciencesXiamen UniversityXiamen 361005China Meteorological Observation Centre China Meteorological AdministrationBeijing 100081China College of Marine Technology Faculty of Information Science and EngineeringOcean University of ChinaQingdao 266100China

Accurate and comprehensive knowledge of the atmospheric environment and its evolution within the coastal ocean boundary layer are necessary for understanding the sources,chemical mechanisms,and transport processes of air pollution in land,sea,and *** present an overview of coastal ocean boundary layer detection technology and equipment in China and summarize the progress and main achievements in recent *** has developed a series of coastal ocean boundary layer detection technologies,including Light Detection and Ranging(LIDAR),turbulent exchange analyzer,air-sea flux analyzer,stereoscopic remote sensing of air pollutants,and oceanic aerosol detection equipment to address the technical bottleneck caused by harsh environmental conditions in coastal ocean *** in these technologies and equipment have provided scientific assistance for addressing air pollution issues and understanding land-sea-atmosphere interactions over coastal ocean regions in *** the future,routine atmospheric observations should cover the coastal ocean boundary layer of China.

关键词： Atmospheric pollution Coastal ocean Atmospheric monitoring Environmental instrument

Hard state of the urban canopy layer turbulence and its self-similar multiplicative cascade models

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第Z2期48卷 80-87页

作者： HU Fei cheng xueling ZHAO Songnian QUAN Lihong LAPC Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China LAPC Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China LAPC Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China LAPC Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

It is found by experiment that under the thermal convection condition, the temperature fluctuation in the urban canopy layer turbulence has the hard state character, and the temperature difference between two points has the exponential probability density function distribution. At the same time, the turbulent energy dissipation rateεfits the log-normal distribution, and is in accord with the hypothesis proposed by Kolmogorov in 1962 and lots of reported experimental results. In this paper, the scaling law of hard state temperature n order structure function is educed by the self-similar multiplicative cascade models. The theory formula isζn = n/3-μ{n(n+6)/72+[2lnn!-nln2]/2ln6}, andμis intermittent exponent. The formula can fit the experimental results up to order 8 exponents, is superior to the predictions by the Kolmogorov theory, the p and log-normal model.

关键词： atmospheric boundary layer, urban canopy layer, atmospheric turbulence, turbulence cascade.

Gustiness and Coherent Structure of Strong Winds and Their Role in Dust Emission and Entrainment

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2010年第1期27卷 1-13页

作者：曾庆存程雪玲胡非彭珍 Institute of Atmospheric Physics Chinese Academy of Sciences Department of Atmospheric Science Nanjing University

After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into *** strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.

关键词： gust-wind coherent structure descending motion dust storm soil erosion dust entrainment

风能模型的发展及CFD在风资源开发利用中的应用

在线全文

学校读者我要写书评

暂无评论

空气动力学学报 2023年第6期41卷 1-15,I0001页

作者：程雪玲中国科学院大气物理研究所北京100029 中国科学院大学地球与行星科学学院北京101408

风能科学的发展一个很重要的方面就是从大气运动到风力发电机尺度流场的不同时空尺度运动的研究。随着计算能力的发展,计算流体力学(computational fluid dynamics,CFD)已经广泛应用于风能开发领域,使得风能模型从应用于较平坦地形的线... 详细信息

风能科学的发展一个很重要的方面就是从大气运动到风力发电机尺度流场的不同时空尺度运动的研究。随着计算能力的发展,计算流体力学(computational fluid dynamics,CFD)已经广泛应用于风能开发领域,使得风能模型从应用于较平坦地形的线性模型,发展到应用于复杂地形、耦合天气过程,考虑风力发电机排布、尾流效应的模型链。本文首先介绍了目前风能评估、微观选址、风功率预测模型的发展,之后详细介绍了在这些风能模型中CFD方法的改进,主要集中在中尺度到微尺度的“降尺度”、尾流模拟和复杂地形风场模拟3个方面,最后对风能模型发展过程中CFD所面临的挑战进行了展望。

关键词：风能 CFD 降尺度复杂地形尾流

同方期刊数据库

在线全文

学校读者我要写书评

暂无评论

燃气源开槽导管三维流场的数值模拟

推进技术 1999年第4期20卷 43-47页

作者：程雪玲张平北京理工大学机电工程学院

为了解某火箭弹控制系统燃气源开槽导管内的气流流动特性，通过ＳＩＭＰＬＥ方法对其复杂流场进行了数值模拟。采用隐式时间分裂格式、幂函数方案及交错网格修正压力等方法，获得了燃烧室后部和导管内气流的速度、压力、密度和温度的三... 详细信息

为了解某火箭弹控制系统燃气源开槽导管内的气流流动特性，通过ＳＩＭＰＬＥ方法对其复杂流场进行了数值模拟。采用隐式时间分裂格式、幂函数方案及交错网格修正压力等方法，获得了燃烧室后部和导管内气流的速度、压力、密度和温度的三维分布。

关键词：燃气发生器喷管气流三维流场数值计算火箭弹