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LBE simulation of impinging stream inside a T-junction mixer

Science China(Technological Sciences) 2018年第7期61卷 1038-1055页

作者： XU WenKai zhang qingchen GUI Nan zhang ZiWei College of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China Beijing National Railway Research&Design Institute of Signal&Communication Co. Ltd Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Lattice Boltzmann Equation(LBE) method is utilized to simulate impinging stream(IS) in a T-junction mixer using a TD2G9 model. It aims to investigate the influence of Reynolds number(Re), aspect ratio of outlet diameter to inlet diameter, ratio of opposite inlet velocities, and the thermal boundary conditions on flow, mixing and heat transfer characteristics. In particular, the vortex evolution, velocity distribution, mixing index and Nusselt number(Nu) distribution in the T-junction mixer are explored in details. Four types of vortices and flow regimes are observed. The instantaneous and time-averaged flow and thermal fields,including vortex structure, transition of flow regimes, streamline and the Nusselt number distribution are discussed. Distinct quantitative transitions, even for dramatic change, are observed near the critical Re. At a low or moderate aspect ratio, the symmetric coherent structure is observed in an unstable flow regime. At a larger aspect ratio, the flow in the T-mixer becomes turbulent and asymmetric. The unequal injections velocities of the nozzles impose significant influence on the flow structure,mixing and heat transfer in vertical tube. Using larger difference between the two inlet velocities can result in more obvious change in flow characteristics. Moreover, mixing index is found to be valid in evaluating the mixing degree under a sinusoidal inlet velocity.

关键词： impinging flow lattice Boltzmann method T-junction heat transfer flow characteristics

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Effects of micro-oxygenation on the aroma of Cabernet Sauvignon wine from Ningxia,China

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International Journal of Agricultural and Biological Engineering 2022年第4期15卷 251-263页

作者： Zhong zhang qingchen zhang Huiqing Wang Hongchuan Xia Lijun Sun Junxiang zhang School of Life Sciences Ningxia UniversityYinchuan 750021China College of Pharmacy University of FloridaGainesville FL32610USA School of Agriculture Ningxia UniversityYinchuan 750021China School of Food and Wine Ningxia UniversityYinchuan 750021China China Wine Industry Technology Institute Yinchuan 750021China

Micro-oxygenation (MOX) is an effective post-harvest technique for the flavor improvement of grape wine. This study investigated the effect of MOX on the aroma quality of Ningxia wine for the first time. Three sub-region Cabernet Sauvignon dry red wines were treated with different levels of oxygen before or after malolactic fermentation. The wine aroma was analyzed through gas chromatography-mass spectrometry (GC-MS) and quantitative descriptive analysis (QDA) after six months of aging. The data obtained demonstrated that the dose and timing of oxygen addition were key factors influencing the effectiveness of MOX. The most noticeable modifications in wine aroma compounds were generated by an oxygen dosage of 30 (mL/L)/month added before malolactic fermentation. Predominantly, the concentrations of 2-phenylethanol, benzaldehyde, diacetyl, and 2,3-pentanedione showed an increased pattern upon MOX treatments. The sensory analysis revealed that MOX improved the aroma quality of wine by decreasing green and animal odors, meanwhile enhancing the olfactory intensities of dried fruits, flowers, and nuts. This work confirmed that MOX was suitable for aroma modification of Cabernet Sauvignon dry red wine from Ningxia and established a preliminary MOX procedure that can serve as a reference for future applications.

关键词： grape wine micro-oxygenation volatile organic compounds aroma profiles Ningxia

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THE INTERNAL HYDROGRAPHIC STRUCTURE OF THE HUANGHAI COLD WATER MASS (HCWM) IN SUMMER

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Chinese Journal of Oceanology and Limnology 1986年第1期4卷 27-40页

作者： Zhao Baoren, Xiong qingchen and zhang Fagao (Institute of Oceanology, Academia Sinica) 1. Institute of Oceanology Academia Sinica Qingdao China

The deep and bottom water within the Huanghai Cold Water Mass (HCWM) in summer was, for a long time, considered as a homogeneous body of water. Various investigations in recent years showed this may not be *** a detailed analysis of the most recently obtained refined CTD data and other historical hydrographic data at our disposal, some significant results have been *** is definitely shown that the Huanghai Warm Current (HWC) did not enter the HCWM in summer. However, there exist two types of second class water masses within the HCWM in summer. They are: (1) a water mass with low temperature and low salinity, which was formed in the preceding winter by a vertical mixing process locally, and (2) a water mass of relatively high temperature and high salinity, which is the remanent body of the HWC that entered the HCWM in preceding seasons, but was completely cut off from its source in summer. The spreading of these two water masses, the existence of a frontal zone at the boundary of the two

关键词： IN SUMMER THE INTERNAL HYDROGRAPHIC STRUCTURE OF THE HUANGHAI COLD WATER MASS HCWM

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THE DISTRIBUTION CHARACTERISTICS OF TURBULENCE ON LEESIDE OF WINDBREAKS

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Journal of Northeast Forestry University 1992年第1期3卷 23-28页

作者： Wang Zhengquan Wang Ke zhang Yandong Wang qingchen Northeast Forestry University 1. Northeast Forestry University China

The distributive characteristics of turbulence, turbulent velocity, turbulent intensity and Reynolds stress, in horizontal and vertical direction on leeward side of windbreak were discussed in this paper. The results show that all the three kinds of parameters of turbulence have the similar distributive patterns in lee, their peaks were around 10H for horizontal and Z/ H = 1 for vertical. The windbreak is important barrier to affect the structure and distribution of wind speed and turbulence. Porosities of windbreaks could alter the patterns of turbulence, therefore, affect the abilities and functions of windbreaks.

关键词： Windbreak Turbulence

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Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching

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Science China Earth Sciences 2004年第z2期47卷 74-85页

作者： zhang Zhongpei WANG qingchen Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and evolution. As sensitive markers of small stress changes, joint and shear fracture, characterized by consistency of ori-entation over wide area, can be used to reconstruct paleostress state and its evolution. Detailed observations and analysis on the orientations, geometrical patterns, sequences of joints and shear fractures and their chronological relation to faults and folds show that, the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different orientations. And the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different orientations. According to the rela-tionships between joint and shear fractures and stress, the NEE-SWW systematic joints are in-ferred to result from lateral weak extension caused by the late Cretaceous regional uplift, while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the Neogene. But some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa depression. At the beginning of the Neogene, the stress field changed and the maximal principal stress s1 switched from vertical to horizontal.

关键词： joint, shear fracture, paleostress, paleostress field, Kuqa depression.

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A Method for Software Vulnerability Detection Based on Improved Control Flow Graph

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Wuhan University Journal of Natural Sciences 2019年第2期24卷 149-160页

作者： ZHOU Minmin CHEN Jinfu LIU Yisong ACKAH-ARTHUR Hilary CHEN Shujie zhang qingchen ZENG Zhifeng School of Computer Science and Communication Engineering Jiangsu University

With the rapid development of software technology, software vulnerability has become a major threat to computer security. The timely detection and repair of potential vulnerabilities in software, are of great significance in reducing system crashes and maintaining system security and integrity. This paper focuses on detecting three common types of vulnerabilities: Unused_Variable, Use_of_Uninitialized_Variable, and Use_After_ Free. We propose a method for software vulnerability detection based on an improved control flow graph(ICFG) and several predicates of vulnerability properties for each type of vulnerability. We also define a set of grammar rules for analyzing and deriving the three mentioned types of vulnerabilities, and design three vulnerability detection algorithms to guide the process of vulnerability detection. In addition, we conduct cases studies of the three mentioned types of vulnerabilities with real vulnerability program segments from Common Weakness Enumeration(CWE). The results of the studies show that the proposed method can detect the vulnerability in the tested program segments. Finally, we conduct manual analysis and experiments on detecting the three types of vulnerability program segments(30 examples for each type) from CWE, to compare the vulnerability detection effectiveness of the proposed method with that of the existing detection tool Cpp Check. The results show that the proposed method performs better. In summary, the method proposed in this paper has certain feasibility and effectiveness in detecting the three mentioned types of vulnerabilities, and it will also have guiding significance for the detection of other common vulnerabilities.

关键词： software security software vulnerability improved control flow graph vulnerability detection algorithm

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Power-law Spectrum Analysis on Uncertainties of Rate Estimated from GPS Coordinates Time Series

Power-law Spectrum Analysis on Uncertainties of Rate Estimat...

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第九届中国卫星导航学术年会

作者： qingchen zhang Bingbing Duan Urs Hugentobler Technische Universit?t München

The ground station velocity derived from GPS coordinates time series is one of the important elements for assessing the stability of the global reference frame. Precisely characterizing this parameter includes finding the reliable uncertainty of the station velocity. In the article, we present a method to monitor velocity uncertainties from GPS coordinates time series which are corrupted by temporally correlated noise. A power-law noise plus white noise model is used in the research to prevent underestimation of the uncertainties and is parameterized in terms of orthonormal wavelet bases. Then the unknown parameters of the noise model can be iteratively estimated by the expectation-maximization algorithm and can be applied in Kalman filter. Nevertheless, different from white noise and random walk noise which can be characterized by an integer-ordered transfer function, the power-law noise in the GPS coordinates time series is mathematically described by fractional-order calculus, which means that it is impossible to find a finite integer-ordered filter to fit its straight line spectrum for all frequencies. As a consequence, an Oustaloup’s filter based numerical algorithm is developed to build a feasible state-space model describing such power-law noise. By applying the proposed state-space model in the Kalman filter, it is possible to estimate the velocity uncertainties in the real-time and the viability of the algorithm is verified by the results from simulations and the data of IGS station WTZR.

关键词： Power-law noise GPS time series Wavelets Kalman filter

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基于上下行波分解的分数阶拉普拉斯算子黏滞声波逆时偏移成像方法

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石油地球物理勘探 2023年第4期58卷 872-882页

作者：王喜鹏张庆臣毛伟建中国科学院精密测量科学与技术创新研究院计算与勘探地球物理研究中心湖北武汉430077 大地测量与地球动力学国家重点实验室湖北武汉430077 中国科学院大学北京100049

地下介质通常存在黏滞性,使地震波在传播过程中产生能量衰减及(相位)频散效应,降低了偏移成像照明能量。采用互相关成像条件的双程波动方程逆时偏移技术,当速度模型精度不高或存在较强速度梯度时,可能会产生低频噪声和假象。为此,提出... 详细信息

地下介质通常存在黏滞性,使地震波在传播过程中产生能量衰减及(相位)频散效应,降低了偏移成像照明能量。采用互相关成像条件的双程波动方程逆时偏移技术,当速度模型精度不高或存在较强速度梯度时,可能会产生低频噪声和假象。为此,提出一种基于上下行波分解的解耦分数阶拉普拉斯算子黏滞声波逆时偏移成像(Q补偿逆时偏移)方法,采用解耦的分数阶拉普拉斯算子黏滞声波方程分别对震源波场和检波点波场进行外推,在此过程中校正地下介质对地震波产生的衰减效应;引入自适应稳定因子应对地震波衰减补偿过程中数值不稳定问题;采用时间解析波场外推方法,在时间切片上分别对震源、检波点波场的传播方向进行分解;最终运用互相关成像条件对下行的震源波场和上行的检波点波场进行成像。数值测试结果表明,所采用的Q补偿逆时偏移方法可校正由地下介质黏性特性引起的地震波振幅衰减和(相位)频散效应,该成像方法能显著减少传统逆时偏移成像中的低频噪声与假象。

关键词： Q补偿逆时偏移波场分解低频噪声分数阶

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三维最小二乘弹性高斯束叠前深度偏移

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地球物理学报 2021年第11期64卷 4181-4195页

作者：孙昌潇毛伟建张庆臣石星辰中国科学院精密测量科学与技术创新研究院计算与勘探地球物理研究中心大地测量与地球动力学国家重点实验室武汉430077 中国科学院大学北京100049

与声波高斯束成像相比,弹性波高斯束偏移更适用于复杂油气藏多波多分量地震勘探.但是由于观测系统的局限性和深部构造的复杂性,该方法同样存在成像分辨率低、照明不均衡等问题.本文结合最小二乘偏移和弹性高斯束偏移的优势,提出了一种... 详细信息

与声波高斯束成像相比,弹性波高斯束偏移更适用于复杂油气藏多波多分量地震勘探.但是由于观测系统的局限性和深部构造的复杂性,该方法同样存在成像分辨率低、照明不均衡等问题.本文结合最小二乘偏移和弹性高斯束偏移的优势,提出了一种通过弹性高斯束叠加构建Born正演(反偏移)算子和偏移算子的三维最小二乘叠前深度偏移方法.依据最小二乘反演理论,建立基于反偏移数据与实际观测数据残差的目标函数,采用共轭梯度算法迭代更新来建立地下真实的反射率.与传统弹性高斯束偏移方法相比,该方法不仅提高了成像分辨率,而且使复杂构造特别是陡倾角地层的成像照明也得到了补偿.理论模型测试结果证明了本文方法的可行性和有效性.

关键词：弹性高斯束最小二乘偏移 Born正演共轭梯度法

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基于密度扰动的点扩散函数计算与三维深度域模拟成像

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地球物理学报 2022年第4期65卷 1402-1415页

作者：段伟国毛伟建张庆臣石星辰张建磊中国科学院精密测量科学与技术创新研究院计算与勘探地球物理研究中心大地测量与地球动力学国家重点实验室武汉430077 中国科学院大学北京100049 中国石油集团公司东方地球物理公司物探技术研究中心河北涿州072751

点扩散函数(point spread function,简称PSF)是成像系统对单位强度点散射体的响应,基于PSF的反演方法为直接在深度域进行储层参数反演提供了新的方向.本研究旨在提出一种切实可行的PSF计算方法,并利用PSF得到深度域模拟成像.本文从扰动... 详细信息

点扩散函数(point spread function,简称PSF)是成像系统对单位强度点散射体的响应,基于PSF的反演方法为直接在深度域进行储层参数反演提供了新的方向.本研究旨在提出一种切实可行的PSF计算方法,并利用PSF得到深度域模拟成像.本文从扰动理论出发,分析了速度和密度扰动对散射场的影响,在前人工作的基础上提出了基于密度扰动的两步正演法来计算PSF.然后,深入研究了如何去除模拟成像过程中的结构信息污染,如何进行相位匹配以及空间褶积的实现细节等问题,并提出了相应的有效解决方案.模型测试表明采用本文提出的计算方法得到的PSF具有准确、污染小的特点,并且基于PSF得到的深度域模拟成像剖面在振幅和相位上都与实际偏移成像结果匹配良好.

关键词：点扩散函数深度域模拟成像相位匹配

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