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VIBRATION AND STABILITY OF VERTICAL UPWARD-FLUID-CONVEYING PIPE IMMERSED IN RIGID CYLINDRICAL CHANNEL

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Acta Mechanica Solida Sinica 2008年第5期21卷 431-440页

作者： qin qian Lin Wang Qiao Ni Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China

A theoretical model is developed for the vibration and stability of a vertical pipe subjected concurrently to two dependent axial flows. The external fluid, after exiting the outer annular region between the pipe and a rigid cylindrical channel, is conveyed upwards inside the pipe. This configuration thus resembles of a pipe that aspirating fluid. The equation of planar mo- tion is solved by means of the differential quadrature method （DQM）. Calculations are conducted for a slender drill-string-like and a bench-top-size system, for different confinement conditions of the outer annular channel. It is shown that the vibrations of these two systems are closely related to the degree of confinement of the outer annular channel. For a drill-string-like system with narrow annuli, buckling instability may occur in the second and third modes. For a bench-top-size system, however, both buckling and flutter may occur in the lowest three modes. The form of instability depends on the annuli size.

关键词： pipe conveying fluid annular flow axial flow drill-string stability critical flow velocity

快速气相色谱法测定汽油单体烃组成及多项物性预测模型的建立

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石油炼制与化工 2025年第1期56卷 172-180页

作者：李长秀王亚敏张祎玮王征钱钦中石化石油化工科学研究院有限公司北京100083

建立了采用40 m×0.10 mm×0.20μm超细内径非极性色谱柱、氢气作载气的快速分析汽油馏分单体烃组成的方法(简称快速单体烃分析方法)。对于催化裂化汽油C_(3)~C_(12)组分可以得到367个色谱峰,正十二烷的保留时间为30.1 min。同一样品重... 详细信息

建立了采用40 m×0.10 mm×0.20μm超细内径非极性色谱柱、氢气作载气的快速分析汽油馏分单体烃组成的方法(简称快速单体烃分析方法)。对于催化裂化汽油C_(3)~C_(12)组分可以得到367个色谱峰,正十二烷的保留时间为30.1 min。同一样品重复测定3次的结果显示组分保留时间极差小于0.02 min,保留指数极差小于0.50。对于质量分数大于0.5%的单体烃组分,含量测定结果的相对标准偏差小于6%;对于质量分数小于0.5%的单体烃组分,含量测定结果的相对标准偏差小于10%。建立了根据汽油单体烃分析结果计算汽油的密度、饱和蒸气压、折射率、碳氢元素含量、平均相对分子质量、溴值的修正计算模型。根据修正模型计算样品的密度、折射率和饱和蒸气压,计算结果与实测结果有较好的一致性。根据快速单体烃分析方法的测定结果和采用50 m×0.20 mm×0.50μm非极性色谱柱的常规单体烃分析方法的测定结果计算多项物性参数,两种方法下的计算结果一致,说明建立的计算模型也适用于采用快速单体烃分析方法的测定结果计算样品的多项物性参数。

关键词：汽油单体烃快速分析气相色谱物性参数

NONLINEAR RESPONSES OF A FLUID-CONVEYING PIPE EMBEDDED IN NONLINEAR ELASTIC FOUNDATIONS

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Acta Mechanica Solida Sinica 2008年第2期21卷 170-176页

作者： qin qian Lin Wang Qiao Ni Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China

The nonlinear responses of planar motions of a fluid-conveying pipe embedded in nonlinear elastic foundations are investigated via the differential quadrature method discretization （DQMD） of the governing partial differential equation. For the analytical model, the effect of the nonlinear elastic foundation is modeled by a nonlinear restraining force. By using an iterative algorithm, a set of ordinary differential dynamical equations derived from the equation of motion of the system are solved numerically and then the bifurcations are analyzed. The numerical results, in which the existence of chaos is demonstrated, are presented in the form of phase portraits of the oscillations. The intermittency transition to chaos has been found to arise.

关键词： fiuid-conveying pipe nonlinear elastic foundation chaotic motion bifurcation differential quadrature method discretization (DQMD)

CHAOTIC TRANSIENTS IN A CURVED FLUID CONVEYING TUBE

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Acta Mechanica Solida Sinica 2005年第3期18卷 207-214页

作者： Ni Qiao Wang Lin qian qin Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China

The chaotic transients of a curved fluid conveying tube subjected to a nonlinear foundation are investigated. The assumption of the inextensibility of the tube is applied to derive the nonlinear differential equation of motion via the Newtonian approach, with the differential quadrature method used to discretize the curved tube model in the spatial domain. And the nonlinear dynamic motion equation is obtained. The numerical analysis shows that, the final steady states are sensitive to the initial system conditions in a large parameter region of the fluid speed. This phenomenon of chaotic transients is infrequent for fluid conveying tubes.

关键词： curved fluid conveying tube chaotic transient nonlinear dynamics DQM

Monitoring and evaluation of the water quality of the Lower Neches River, Texas, USA

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Water Science and Engineering 2024年第1期17卷 21-32页

作者： qin qian Mengjie He Frank Sun Xinyu Liu Department of Civil and Environmental Engineering Lamar UniversityBeaumontTX 77710USA Department of Industry Engineering Lamar UniversityBeaumontTX 77710USA Department of Computer Science Lamar UniversityBeaumontTX 77710USA

Increasing bacteria levels in the Lower Neches River caused by Hurricane Harvey has been of a serious *** study is to analyze the historical water sampling measurements and real-time water quality data collected with wireless sensors to monitor and evaluate water quality under different hydrological and hydraulic *** statistical and Pearson correlation analysis on historical water samples determines that alkalinity,chloride,hardness,conductivity,and pH are highly correlated,and they decrease with increasing flow rate due to *** flow rate has positive correlations with Escherichia coli,total suspended solids,and turbidity,which demonstrates that runoff is one of the causes of the elevated bacteria and sediment loadings in the *** correlation between *** and turbidity indicates that turbidity greater than 45 nephelometric turbidity units in the Neches River can serve as a proxy for *** to indicate the bacterial outbreak.A series of statistical tools and an innovative two-layer data smoothing filter are developed to detect outliers,fill missing values,and filter spikes of the sensor *** correlation analysis on the sensor data illustrates that the elevated sediment/bacteria/algae in the river is either caused by the first flush rain and heavy rain events in December to March or practices of land use and land ***,utilizing sensor measurements along with rainfall and discharge data is recommended to monitor and evaluate water quality,then in turn to provide early alerts on water resources management decisions.

关键词： Water quality Pearson correlation analysis Lower Neches River YSI wireless sensors Non-point pollution

A MIXED FE-BE METHOD FOR COUPLED VIBRATION OF GRAVITY DAM-RESERVOIR SYSTEM WITH VARIABLE WATER DEPTH

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Acta Mechanica Solida Sinica 1998年第2期11卷 123-132页

作者： Jin Tao Huang Yuying qian qin Huazhong Univ Sci & Technol Dept Mech Wuhan 430074 Peoples R China

To solve the coupled vibration of a gravity dam-reservoir systemwith variable water depth by using a hybrid element method, the fluidregion with variable water depth needs to be dis- cetized by FEmeshes. However, such a method asks for a great computational costowing to the ex- cessive unknowns, especially when the fluid regionwith variable water depth is relatively large. To overcome theshortcoming, a refined boundary element method is proposed to analyzethe fluid field, in which only the discretization for the boundary ofthe variable depth region is required. But as a basis of thisapproach, it is necessary to construct a new Green's functioncorresponding to an infinite strip region.

关键词： mixed FE-BE method fluid-solid interaction gravity dam

EXPERIMENTAL STUDY OF THE NON-DARCY FLOW AND SOLUTE TRANSPORT IN A CHANNELED SINGLE FRACTURE

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Journal of Hydrodynamics 2011年第6期23卷 745-751页

作者： CHEN Zhou qian Jia-zhong qin Hua School of Resources and Environmental Engineering Hefei University of Technology Hefei 230009 China

The characterization of fracture rocks is always a key issue in understanding the flow and solute transport in fractured media. This article studies the solute transport in a Channeled Single Fracture （CSF）, a single fracture with contact in certain areas. The flow in a CSF often has preferential pathways and the transport in a CSF often has Break Through Curves （BTCs） with long tails. The Surface Contact Ratio （SCR）, the ratio of the contact area to the total fracture area, is an important indicator for the fracture surface roughness. To study the flow and solute transport in a CSF, a controlled physical model is constructed and a series of flow and tracer test experiments are carried out. Under our experimental conditions, the flow in a CSF is found to follow the Forchheimer equation , where and are the hydraulic gradient and the average pore velocity, respectively and and are two parameters related to the viscous and inertial flow components, respectively. Furthermore, it is found that b decreases with the decrease of SCR. For the solute transport, it is found that the BTCs often deviate from the traditional Fickian behavior, by the early-arrival and the long tailing. More interestingly, the observed BTCs often have a double-peak or a multi-peak, that would be difficult to explain using the existing transport theory such as the Advection-Dispersion Equation （ADE）. In addition, the longitudinal dispersion coefficient is found to be scale-dependent in a CSF and the relationship is of exponential type.

关键词： channeled single fracture surface contact ratio non-Darcian non-Fickian

STUDY OF TOPOLOGY OPTIMIZATION FOR THERMO-STRUCTURAL COUPLING FIELD

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Acta Mechanica Solida Sinica 2005年第4期18卷 357-364页

作者： Zuo Kongtian qian qin Zhao Yudong Chen Liping Department of Automotive Engineering Tsinghua University Beijing 100084 China Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China CAD center Huazhong University of Science and Technology Wuhan 430074 China

A number of critical problems of topology optimization concerning the thermostructural coupling field axe studied at length. The governing equations and topology optimization model for the thermal-structural coupling field axe derived, with an adjoint method for sensitivity analysis of the thermo-structural coupling field proposed. The optimization algorithm for coupling field topology optimization is investigated and a flowchart of coupling field topology optimization presented. The theory and algorithms axe implemented and verified by two numerical examples.

关键词： thermo-structural coupling field topology optimization sensitivity analysis numerical calculation

THEORETICAL INVESTIGATION ON THE DYNAMIC PERFORMANCE OF CMUT FOR DESIGN OPTIMIZATION

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Acta Mechanica Solida Sinica 2013年第1期26卷 99-110页

作者： Ting Yu Wenchao Zhou Peng Xu Fengqi Yu qin qian Department of Integrated Electronics Shenzhen Institute of Advanced TechnologyChinese Academy of Sciences The Chinese University of Hong Kong School of Civil Engineering and Mechanics Huazhong University of Sciences and Technology

Although many modeling approaches exist for analyzing the behavior of capacitive micro-machined ultrasonic transducers （CMUTs）, the relation equation between the design pa- rameters with input and output is still lacking. What there is can only be used to analyze the dynamic performance of CMUT indirectly and qualitatively, such as stiffness and sound pressure. A lumped-parameter theoretical model based on the dynamic theory is proposed in this paper. The relation equations between the design parameters with inputs and outputs are given. The results obtained by the proposed model agree well with those by finite element method （FEM） simulation. The dynamic and static behavior of CMUT can be clearly depicted, which is helpful for design and optimization iterations. This shows that the proposed model makes it easier to optimize the parameters of a CMUT with respect to output and bandwidth directly and to better understand the influence of each parameter.

关键词： CMUT dynamic theory finite element method