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整合取向社会工作视角下都市单身青年婚恋态度

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中国青年研究 2024年第3期 42-50页

作者：姜振华琚晓燕李燕平中国青年政治学院社会工作系

根据期待婚恋程度以及择偶状态的不同,本文将都市单身青年的婚恋态度分为五种类型。通过对北京市单身青年的实证研究发现,相当比例的单身青年持有负面婚恋态度,或焦虑,或佛系,或恐惧,陷入了各种各样的婚恋迷茫中。本文从整合取向社会工... 详细信息

根据期待婚恋程度以及择偶状态的不同,本文将都市单身青年的婚恋态度分为五种类型。通过对北京市单身青年的实证研究发现,相当比例的单身青年持有负面婚恋态度,或焦虑,或佛系,或恐惧,陷入了各种各样的婚恋迷茫中。本文从整合取向社会工作视角出发,以“人在情境中”为分析框架,从个体、社会环境、个体与环境互动三个层面系统性探究了单身都市青年负面婚恋态度的生成规律和机制。为此本文建议采取系统性、整合性的干预之道,从实现青年个体增能、促进青年与环境的良性互动、营造包容支持的社会环境三个层面,解决青年的婚恋问题,促进单身青年形成积极、健康、理性的婚恋态度。

关键词：都市单身青年婚恋态度整合取向社会工作

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短脉冲激光加工微结构及其成型技术研究

Journal of Donghua University(English Edition) 2024年第1期41卷 72-80页

作者：虞宙崔金晔胡俊姜振华东华大学人工智能研究院上海201620 东华大学机械工程学院上海201620 上海市高性能纤维复合材料协同创新中心上海201620

短脉冲激光具有高精度、非接触和高可控性等优点,可以针对各种材料进行表面精细加工。如在医用钛合金表面加工出不同形貌、尺寸的微结构,能够有效地改善植入物表面生物活性。利用短脉冲激光在材料加工上的优势,开展了纳秒激光脉冲烧蚀试... 详细信息

短脉冲激光具有高精度、非接触和高可控性等优点,可以针对各种材料进行表面精细加工。如在医用钛合金表面加工出不同形貌、尺寸的微结构,能够有效地改善植入物表面生物活性。利用短脉冲激光在材料加工上的优势,开展了纳秒激光脉冲烧蚀试验,探究纳秒激光与钛合金间的相互作用。阐明钛合金表面火山坑微结构的形成机理,并开展多脉冲激光参数试验,研究激光参数对微结构成型的影响,建立参数与特征尺寸间的映射关系。该研究可以获得具有特定尺寸、高加工质量的微结构,有助于短脉冲激光微加工技术的应用,具有良好的学术和工程意义。

关键词：短脉冲激光微加工火山状坑微沟槽

不同频率下缓冲罐体积对有阀线性压缩机管系压力脉动的实验研究

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西北工业大学学报 2024年第2期42卷 286-294页

作者：黄琦丁磊沙鑫权李子成刘少帅蒋珍华董德平中国科学院上海技术物理研究所上海200083 中国科学院大学北京100049

有阀线性压缩机是液氦温区Joule-Thomson(J-T)节流制冷机重要部件,而管系压力脉动会造成制冷机出现温度与制冷量波动,从而影响制冷机温度稳定性。针对有阀线性压缩机管系压力脉动问题,以有线性阻尼的平面波动理论为基础,采用传递矩阵法... 详细信息

有阀线性压缩机是液氦温区Joule-Thomson(J-T)节流制冷机重要部件,而管系压力脉动会造成制冷机出现温度与制冷量波动,从而影响制冷机温度稳定性。针对有阀线性压缩机管系压力脉动问题,以有线性阻尼的平面波动理论为基础,采用传递矩阵法构造了有阀线性压缩机管路缓冲罐压力脉动传递模型,获得有阀线性压缩机脉动质量流量的量化表达。搭建了有阀线性压缩机管系压力脉动测试平台,讨论了压缩机运行频率与进排气缓冲罐体积对压力脉动的影响。研究结果表明:管系压力脉动与压缩机运行频率有关,随着压缩机运行频率增大,管系压力脉动增大。进排气缓冲罐均可有效抑制压力脉动,但两者的压力脉动抑制能力相互独立,且缓冲罐体积越大,压力脉动抑制效果越好。随着缓冲罐体积的增加,进气缓冲罐进口处压力不均匀度减小到164/423,排气缓冲罐出口处压力不均度减小到8/23。

关键词：有阀线性压缩机平面波动理论压力脉动运行频率缓冲罐体积

A High Resolution Low Dissipation Hybrid Scheme for Compressible Flows

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Chinese Journal of Aeronautics 2011年第4期24卷 417-424页

作者： YU Jian YAN Chao jiang zhenhua School of Aeronautic Science and Engineering Beihang University Beijing 100191 China

In this paper, an efficient hybrid shock capturing scheme is proposed to obtain accurate results both in the smooth region and around discontinuities for compressible flows. The hybrid algorithm is based on a fifth-order weighted essentially non-oscillatory （WENO） scheme in the finite volume form to solve the smooth part of the flow field, which is coupled with a characteristic-based monotone upstream-centered scheme for conservation laws （MUSCL） to capture discontinuities. The hybrid scheme is intended to combine high resolution of MUSCL scheme and low dissipation of WENO scheme. The two ingredients in this hybrid scheme are switched with an indicator. Three typical indicators are chosen and compared. MUSCL and WENO are both shock capturing schemes making the choice of the indicator parameter less crucial. Several test cases are carried out to investigate hybrid scheme with different indicators in terms of accuracy and efficiency. Numerical results demonstrate that the hybrid scheme in the present work performs well in a broad range of problems.

关键词： computational aerodynamics hybrid scheme characteristic variables weighted essentially non-oscillatory scheme high resolution low dissipation

High-order implicit discontinuous Galerkin schemes for unsteady compressible Navier–Stokes equations

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Chinese Journal of Aeronautics 2014年第6期27卷 1384-1389页

作者： jiang zhenhua Yan Chao Yu Jian School of Aeronautic Science and Engineering Beihang University

Efficient solution techniques for high-order temporal and spatial discontinuous Galerkin（DG） discretizations of the unsteady Navier–Stokes equations are developed. A fourth-order implicit Runge–Kutta（IRK） scheme is applied for the time integration and a multigrid preconditioned GMRES solver is extended to solve the nonlinear system arising from each IRK stage. Several modifications to the implicit solver have been considered to achieve the efficiency enhancement and meantime to reduce the memory requirement. A variety of time-accurate viscous flow simulations are performed to assess the resulting high-order implicit DG methods. The designed order of accuracy for temporal discretization scheme is validate and the present implicit solver shows the superior performance by allowing quite large time step to be used in solving time-implicit systems. Numerical results are in good agreement with the published data and demonstrate the potential advantages of the high-order scheme in gaining both the high accuracy and the high efficiency.

关键词： Discontinuous Galerkin scheme GMRES solver High order Implicit Runge–Kutta method Unsteady flows

Revisit of dilation-based shock capturing for discontinuous Galerkin methods

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Applied Mathematics and Mechanics(English Edition) 2018年第3期39卷 379-394页

作者： Jian YU Chao YAN zhenhua jiang School of Aeronautic Science and Engineering Beihang University

The idea of using velocity dilation for shock capturing is revisited in this paper, combined with the discontinuous Galerkin method. The value of artificial viscosity is determined using direct dilation instead of its higher order derivatives to reduce cost and degree of difficulty in computing derivatives. Alternative methods for estimating the element size of large aspect ratio and smooth artificial viscosity are proposed to further improve robustness and accuracy of the model. Several benchmark tests are conducted, ranging from subsonic to hypersonic flows involving strong shocks. Instead of adjusting empirical parameters to achieve optimum results for each case, all tests use a constant parameter for the model with reasonable success, indicating excellent robustness of the method. The model is only limited to third-order accuracy for smooth flows. This limitation may be relaxed by using a switch or a wall function. Overall, the model is a good candidate for compressible flows with potentials of further improvement.

关键词： discontinuous Galerkin method axtificial viscosity compressible flow

Suitability of artificial viscosity discontinuous Galerkin method for compressible turbulence

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Science China(Technological Sciences) 2017年第7期60卷 1032-1049页

作者： YU Jian YAN Chao jiang zhenhua School of Aeronautic Science and Engineering Beijing University of Aeronautics and AstronauticsBeijing 100191China

A discontinuous Galerkin method based on an artificial viscosity model is investigated in the context of the simulation of compressible turbulence. The effects of artificial viscosity on shock capturing ability, broadband accuracy and under-resolved instability are examined combined with various orders and mesh resolutions. For shock-dominated flows, the superior accuracy of high order methods in terms of discontinuity resolution are well retained compared with lower ones. For under-resolved simulations, the artificial viscosity model is able to enhance stability of the eighth order discontinuous Galerkin method despite of detrimental influence for accuracy. For multi-scale flows, the artificial viscosity model demonstrates biased numerical dissipation towards higher wavenumbers. Capability in terms of boundary layer flows and hybrid meshes is also *** is concluded that the fourth order artificial viscosity discontinuous Galerkin method is comparable to typical high order finite difference methods in the literature in terms of accuracy for identical number of degrees of freedom, while the eighth order is significantly better unless the under-resolved instability issue is raised. Furthermore, the artificial viscosity discontinuous Galerkin method is shown to provide appropriate numerical dissipation as compensation for turbulent kinetic energy decaying on moderately coarse meshes, indicating good potentiality for implicit large eddy simulation.

关键词： discontinuous Galerkin method artificial viscosity compressible turbulence implicit large eddy simulation

On the use of the discontinuous Galerkin method for numerical simulation of two-dimensional compressible turbulence with shocks

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1758-1770页

作者： YU Jian YAN Chao jiang zhenhua School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics

In this paper,the discontinuous Galerkin(DG)method combined with localized artificial diffusivity is investigated in the context of numerical simulation of broadband compressible turbulent flows with shocks for under-resolved ***,the spectral property of the DG method is analyzed using the approximate dispersion relation(ADR)method and compared with typical finite difference methods,which reveals quantitatively that significantly less grid points can be used with DG for comparable numerical *** several typical test cases relevant to problems of compressible turbulence are simulated,including one-dimensional shock/entropy wave interaction,two-dimensional decaying isotropic turbulence,and two-dimensional temporal mixing *** results indicate that higher numerical accuracy can be achieved on the same number of degrees of freedom with DG than high order finite difference ***,shocks are also well captured using the localized artificial diffusivity *** results in this work can provide useful guidance for further applications of DG to direct and large eddy simulation of compressible turbulent flows.

关键词： discontinuous Galerkin compressible turbulence shock capturing artificial diffusivity

Simple and robust h-adaptive shock-capturing method for flux reconstruction framework

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Chinese Journal of Aeronautics 2023年第7期36卷 348-365页

作者： Lintao HUANG zhenhua jiang Shuai LOU Xin ZHANG Chao YAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Research Office No.12 Beijing Institute of Astronautical Systems EngineeringBeijing 100076China

In this paper,a simple and robust shock-capturing method is developed for the Flux Reconstruction(FR)framework by combining the Adaptive Mesh Refinement(AMR)technique with the positivity-preserving *** adaptive technique avoids the use of redundant meshes in smooth regions,while the positivity-preserving property makes the solver capable of providing numerical solutions with physical *** compatibility of these two significant features relies on a novel limiter designed for mesh *** ensures the positivity of solutions on all newly created ***,the proposed method is completely positivity-preserving and thus highly *** performs well in solving challenging problems on highly refined meshes and allows the transition of cells at different levels to be completed within a very short *** performance of the proposed method is examined in various numerical *** solving Euler equations,the technique of Local Artificial Diffusivity(LAD)is additionally coupled to damp *** importantly,when solving Navier-Stokes equations,the proposed method requires no auxiliaries and can provide satisfying numerical solutions *** implementation of the method becomes rather simple.

关键词： Adaptive mesh refinement Flux reconstruction Positivity-preserving scheme Robustness Shock-capturing