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Search Results: 1 - 10 of 74843 matches for " 黄晋阳 "
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用区域变换计算单螺杆挤出机流动区域上的三维泊松方程数值解法
,晋阳
- , 2017, DOI: 10.13543/j.bhxbzr.2017.05.019
Abstract: 单螺杆挤出机流体流动区域是一个复杂的区域,其截面为双连通区域,且计算求解此流动区域上的泊松方程是用高效的投影算法求解单螺杆挤出机流体流动问题的核心步骤。利用共形映射将此不规则的双连通区域转化为同心圆环,进一步将复杂的求解区域变为规则的圆环柱体区域,可以大大简化问题的计算,并适用于计算包含漏流层的单螺杆挤出机流体流动问题。以截面内边界曲线为椭圆的单螺杆挤出机为例进行了泊松方程的求解计算,将求得的解与精确解进行了对比,结果表明此方法简单有效。
Abstract:The fluid flow area in a single screw extruder is complex, and its cross section is a bi-connected area. When using an efficient projection algorithm to solve problems of fluid flow in a single screw extruder, the key is to understand the Poisson equation in this area. In this paper, conformal mapping is used to transform an irregular bi-connected area into a concentric ring, and the complicated solution area is then transformed into a regular circular cylinder region. This method can greatly reduce computation for this problem and be applied to problems of fluid flow in a single screw extruder with a leakage layer. As an example, a boundary value problem of a Poisson equation has been solved numerically in the fluid flow area of a single screw extruder with an elliptical inner boundary in the cross section, and the numerical solution compared with the exact one. The numerical results shows that this method is simple and effective.
螺槽区域上偏微分方程模型的几何变换算法
王国娟,晋阳
- , 2016, DOI: 10. 13543/ j. bhxbzr. 2016. 05. 021
Abstract: 根据螺槽是一族螺线的集合特点,先建立螺旋直角坐标系,并证明了等截面螺槽区域在螺旋直角坐标系下为柱体区域;再利用数值保角变换,将柱体区域变为长方体区域,使得此类求解区域上的偏微分方程(PDE)模型在区域几何变换后易于数值求解;最后对一个矩形螺槽上的三维Poisson 方程边值问题进行了数值计算。结果表明, 此算法有效且易用,为研究单螺杆挤出机中三维流体流动提供了易用可行的基础数值方法。
Abstract:Based on the characteristic that a screw channel is a set of spiral lines, a spiral rectangular coordinate system has been established, and it has been shown that a screw channel domain with uniform section can be converted to a cylindrical domain in this spiral rectangular coordinate system. The cylindrical domain can subsequently be transformed to a cuboid domain by numerical conformal mapping. Partial differential equation (PDE) models of such a domain can then be numerically solved much more easily after this transformation. As an example, a boundary value problem for a 3-D Poisson equation on a screw channel domain with a rectangular section has been solved numerically, and the numerical results demonstrate that the algorithm is effective and easy to use. The algorithm offers a feasible and easy-to-use basic numerical method for the study of 3-D fluid flow in a single screw extruder.
计算双螺杆挤出机流体流动的共形区域变换
李奇强,晋阳
- , 2018, DOI: 10.13543/j.bhxbzr.2018.06.019
Abstract: 双螺杆挤出机机筒内部的流体流动区域截面是随时间变化的复杂三连通区域,采取共形映射方法将这样的三连通区域映射成不随时间变化的圆界区域,进一步将流动区域变成一个不随时间变化的柱形区域,可大幅简化双螺杆挤出机流体流动问题的计算。选择以外边界为圆周、内边界为随时间旋转的两个椭圆周的平面区域上的热传导问题为研究对象,用本文方法进行计算并比较了精确解和数值解,计算结果表明两解的绝对误差较小。本文方法可用于双螺杆挤出机流体流动问题的计算,并简化了计算过程。
Abstract:The main result in this paper is an important method for simplifying computation of fluid flow in a twin screw extruder. The sections of fluid flow area inside the extruder are complex time-dependent three-connected regions. In this paper, conformal mappings are used to map the three-connected regions into time-independent regions with circular boundaries and, in addition, the flow area is mapped into a cylindrical time-independent area. As a result, computation of the fluid flow is greatly simplified. As an example, a heat conduction problem for a region with a circular boundary as the outer boundary and two elliptical boundaries rotating over time as the inner boundaries was solved numerically using our the mapping method. The exact solution and the numerical solution were compared. The numerical results show that our method is feasible and can be used to compute problems relating to the fluid flow in a twin screw extruder.
卷积型volterra积分方程的解的一种新算法
晋阳
武汉理工大学学报 , 1998,
Abstract: ?利用卷积算子讨论卷积型volterra积分方程的解法,得到了解核的一种新算法
THE STUDIES OF SOME ASPECTS OF BIODIVERSITY ON SCRUBS IN THE WARM TEMPERATE ZONE IN CHINA
中国暖温带若干灌丛群落多样性问题的研究

晋阳,陈灵芝
植物生态学报 , 1997,
Abstract: 暖温带灌丛的生物多样性的研究表明:1.灌丛群落的均一度指数同优势度指数的相关性较丰富度指数同变化度指数的相关性为高;在众多的多样性指数中,D4(Shannon信息度指数)和D6(Gini指数)因最大限度地包含了其它各类多样性指数的信息而被采用。2.灌丛群落的物种多样性指数值随着演替的进行,没有表现出降低的趋势。3.生物多样性较高的荆条灌丛和辽东栎萌丛的物种多度分布是对数分布,而生物多样性较低的鬼见
中国暖温带若干灌丛群落多样性问题的研究
晋阳, 陈灵芝
植物生态学报 植物生态学报 , 1997,
Abstract: ?暖温带灌丛的生物多样性的研究表明:1.灌丛群落的均一度指数同优势度指数的相关性较丰富度指数同变化度指数的相关性为高;在众多的多样性指数中,D4(Shannon信息度指数)和D6(Gini指数)因最大限度地包含了其它各类多样性指数的信息而被采用。2.灌丛群落的物种多样性指数值随着演替的进行,没有表现出降低的趋势。3.生物多样性较高的荆条灌丛和辽东栎萌丛的物种多度分布是对数分布,而生物多样性较低的鬼见愁灌丛和毛榛灌丛的物种多度分布是几何分布,处于中间的三桠绣线菊灌丛的物种多度分布是Broken-Stick分布;没有正态对数分布类型。
暖温带落叶阔叶林的物种多样性特征
晋阳,陈灵芝?
生态学报 , 1994,
Abstract: 本文从区域、群落结构和动态出发研究了分布于华北地区的主要落叶阔叶林的物种多样性指数特征,结论如下:(1)随着从北到南纬度的不断降低,落叶阔叶林的物种多样性指数不断增加,优势度指数不断减小.其中,乔木层和灌木层的物种多样性指数均遵循上述规律。草本层的物种多样性指数增加后又降低,优势度指数减低后又增加.(2)海拔1200m以下,物种多样性指数随海拔增加而增加.海拔1200m以上则随海拔增加而减小。(3)乔木层同灌木层间的物种多样性指数具最大的相关注。(4)物种多样性指数从演替初期到中期不断地增加,到演替后期开始下降。
流向变换催化氧化技术的研究与工业应用
朱吉钦,李建伟,韦军,牛学坤,吴慧雄,危丽琼,陈标华,晋阳,潘立登,李成岳
- , 2018, DOI: 10.13543/j.bhxbzr.2018.05.001
Abstract: 低浓度反应物催化氧化反应技术是流程工业、资源与环境工程中一个经常遇到的、重要的共性技术。多年来,北京化工大学工业催化与反应工程研究室对这一领域中一种先进的过程强化技术——流向变换催化氧化技术进行了系统的应用基础、技术开发与工程放大研究。相应地,在结构化催化剂制备、流向变换催化氧化反应器的操作特性、反应/换热系统的过程模型化、模型微分方程组的数值解法与控制技术等方面都做了一系列工作。在此基础上,与协作单位合作,对煤矿乏风(VAM)制热并脱除大量低浓度甲烷、煤制油流程中脱碳塔尾气脱除挥发性有机物(VOCs)等相关技术进行了工程化开发,最终集成为流向变换催化氧化成套技术并实现了工业化和工业装置的长周期、稳定、达标运行。
Abstract:The efficient utilization of the reaction heat in a catalytic oxidation system with lean reactants is an important aim in the processing industry and environmental engineering. In recent years, the adoption of reverse flow reactor (RFR) technology-which is known as an advanced process-enhancement method-in catalytic oxidation reactions has systematically been studied in the Research Institute of Industrial Catalysis and Reaction Engineering in Beijing University of Chemical Technology (BUCT). These studies have covered the theoretical basis, laboratory and pilot investigations, and scale-up to industrial plants. Detailed studies of the preparation of structured catalysts, the experimental operating performance of reverse flow catalytic oxidation reactors, process modeling of the reaction/heat transfer system, numerical solution methods for the differential equations concerned with the unsteady state operation reactor model, and control techniques have been carried out. On the basis of these studies, in cooperation with various partners, the relevant techniques have been integrated into a complete technology package with independent intellectual property rights. Several large-scale plants have been constructed for the destruction of low concentration methane from coal mine ventilation, and for devolatilization of the effluent from the decarbonizing towers of coal-to-oil plants. This technology has been shown to offer long-term and stable operation of industrial plants.
超高压技术在化学研究中的应用
晋阳,程洪斌
自然科学进展 , 2006,
Abstract: 超高压技术近年来得到了快速的发展,特别是金刚石压腔装置的完善,目前已经可以达到550 GPa和6000 K的条件,使其在化学研究中具有巨大的应用前景。压力作为基本的参数,压力作用对物质的电子结构和晶体结构都存在很大的影响。超高压对电子结构的影响包括原子内和原子间,其中原子间的电荷变化包括电荷转移、不均匀分布、以及绝缘体向金属转变。物质的晶体结构在超高压作用下会发生从松散向致密的结构形式的相转变。超高压技术在有机化学反应的选择性、无机固相反应、以及气体的聚合反应等领域都具有重要的应用潜力。
基于反射光谱特性的土壤有机质含量测定仪改进设计
李美清,晋阳
农业机械学报 , 2008, DOI: 10.3969/j.issn.1000-1298.2008.10.081031
Abstract: 阐述了利用有机质的反射光谱特性对土壤有机质含量测定的原理及方法,并设计了测定仪器的总体设计方案、光路系统及仪器的硬件。为了进一步减小测量误差、提高仪器总体性能,在以前研究的基础上对光路系统的设计进行了改进——增加了另外3路光信号以反映土壤光谱在600nm处的弓曲差,研究了不同土样处理方法对土壤有机质含量测量精度的影响。结果表明:在仪器中引入弓曲差信息后,仪器的测量精度得到了进一步提高,测量误差从
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