基于MIKE ZERO 2020的郁江贵港河段一维水质模型

基于MIKE ZERO 2020软件中的HD水动力学模块和AD对流扩散模块,建立郁江贵港市河段的水文、水质信息耦合模型,对郁江贵港河段的水位、流量以及污染物在水体中迁移扩散衰减情况进行了模拟分析。根据郁江近年来的水文资料对模型进行率定并验证。将该模型应用于2023年6月21日~7月6日的洪水过程,结果表明,所建立的模型在率定和验证及应用期间模拟效果均表现良好,模拟精度高。充分证明该模型适用于模拟郁江贵港河段的水文、水质信息变化特征,为提高贵港市防洪、水情预报及水污染预测提供了重要的技术支撑。

偏栅Al_xGa_(1-x)N/GaN HEMT的二维模拟与特性分析

采用泊松方程-薛定谔方程-流体力学方程组自洽求解的方法,对偏栅AlGaN/GaN HEMT器件的电学特性进行了二维模拟。通过与传统正栅器件的模拟结果对比分析,可以看出,偏栅结构除了可以提高器件的击穿电压外,还可以提高直流输出电流和跨导,对输出特性和转移特性均有一定的提高。

海庙港新增通用泊位工程水动力数值模拟

海庙作业区是莱州港的重要组成部分。根据吞吐量预测,现急需建设#5、#6泊位并对码头前沿水域进行疏浚。本文采用MIKE21中HD模块建立渤海湾潮流模型,研究工程建设对水动力环境的影响。为了得到更精确的结果,采用嵌套网格离散工程海域。将数值模型的结果与测站的观测结果进行了对比。潮流的相位差为10min,潮位差10cm。计算得到的潮流流速也与观测结果吻合良好。根据验证结果,作者认为本文建立的数值模型可以比较精确地预测潮流场。基于工程前后不同的岸线和水深数据,分别建立了工程前后的数值模型,通过结果对比,得到以下结论:(1)海庙作业区位于太平湾南部,该海域的潮流为非正规半日潮型,平均涨潮历时大于平均落潮历时,日不等现象较为明显。(2)落急时刻海庙作业区整体水流方向为SW-NE向;涨急时刻海庙作业区北部海域水流流向主要为N-S向,向南逐渐改变为NNW-SSE向。(3)工程建设前,起到挑流作用的主要是作业区西部的堤防;全部工程建设后,起到挑流作用的主要是作业区西部的新码头岸线;工程建设导致码头西部在涨急、落急时刻的流速均有所增大,且增幅超过10cm/s,岸线的变化导致水流方向变化较为明显,最大值超过20°。(4)港池的开挖导致作业区南部水域水流速度明显减小,流态平顺,有利于港池的靠船作业的顺利进行。需要注意的是:港池流速变小有利于泥沙的沉积;来沙方向的来沙量对于港池清淤的间隔时间影响较大,在实际工程中应给予相应的措施。

Numerically investigating the peculiar periphery of a supernova remnant in the medium with a density gradient:the case of RCW 103

The young shell-type supernova remnant RCW 103 has peculiar properties in the X-ray morphology obtained with Chandra.The southeastern shell is brighter in the X-rays,and the curved border of the shell in this region is flatter than the other part.We investigate the formation of the peculiar periphery of the supernova remnant RCW 103 using 3D hydrodynamical simulation.Assuming that the supernova ejecta has been evolved in the medium with a density gradient,the detected shape of the periphery can be generally reproduced.For RCW 103,with the ejecta mass of 3.0 M,the density of the background material of 2.0 cm^(-3),and a gradient of 3.3-4.0 cm^(-3)pc^(-1),the X-ray periphery can be generally reproduced.The simulation turned out that the asymmetry of the SNR RCW 103 is mainly due to the inhomogeneous medium with a density gradient.

An explanation for the peculiar periphery of supernova remnant G309.2–0.6

Supernova remnant（SNR） G309.2–0.6 has a peculiar radio morphology with two bright ears to the southwest and northeast, although the main shell outside the ears is roughly circular. Based on an earlier proposal that the supernova ejecta has a jet component with extra energy, the dynamical evolution of the remnant is solved using 3 D hydrodynamical（HD） simulation to investigate the formation of the periphery of the remnant. Assuming the ejecta with a kinetic energy of 10^51 erg and a mass of 3 M⊙evolved in a uniform ambient medium for a time of-4000 yr and the jet component has cylindrical symmetry with a half open angle of 10°, the result indicates that the energy contained in the jet is about10%–15% of the kinetic energy of the entire ejecta to reproduce the detected profile. This study supports that the remnant originated from a jet-driven core-collapse supernova.

Investigating the morphology of the supernova remnant G349.7+00.2 in the medium with a density gradient

G349.7+00.2 is a young Galactic supernova remnant(SNR)with a mushroom morphology in radio and X-rays,and it has been detected across the entire electromagnetic spectrum from radio to high energyγ-rays.Moreover,the remnant is interacting with a molecular cloud based on the observations in the radio and infrared band.The reason for the formation of the periphery and the dynamical evolution of the remnant is investigated using 3D hydrodynamical(HD)simulations.Under the assumption that the supernova ejecta is evolved in the medium with a density gradient,the shell is composed of two hemispheres with different radii,and the smaller hemisphere is in relatively dense media.The resulting periphery of remnant is consistent with detected ones,and it can be concluded that the peculiar periphery of G349.7+00.2 can be reproduced as the remnants interacting with the medium with a density gradient.

HYDRODYNAMIC AND ELASTOHYDRODYNAMIC STUDIES OF A CYLINDRICAL JOURNAL BEARING

In this article,the effect of the bearing elastic deformation on the performance characteristics of a cylindrical journal bearing is analyzed.The variety of simulation models covers hydrodynamic（HD） and elastohydrodynamic（EHD） lubrication theories.The Reynolds equations governing the flow in the clearance space of the journal bearing are obtained by considering the effect of mass transfer across the fluid film.The finite element method with an iteration scheme was employed to solve both the Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell.The converged solutions for the lubricant flow and elastic deformation vector are obtained.Dynamic characteristics of the journal bearing are computed for HD and EHD theories.Numerical simulation results show that the flexibility of bearing liner has a significant influence on the performance of a cylindrical journal bearing.Indeed,the elastic deformations of the bearing liner extend the pressure area in the bearing and increase the minimum film thickness.Although,dynamic coefficient,load capacity and attitude angle decrease.

水动力清创系统联合去腐生新膏治疗下肢慢性难愈性溃疡气虚血瘀证临床疗效观察

目的:观察应用水动力清创系统联合去腐生新膏治疗下肢慢性难愈性溃疡气虚血瘀证的临床疗效。方法:选取74例下肢难愈性溃疡患者,按照随机数表法分为观察组(25例)、对照1组(25例)、对照2组(24例)。3组入院后均采用水动力清创系统清理创面,观察组清创后予外用去腐生新膏,对照1组外用重组人碱性成纤维生长因子凝胶,对照2组外用湿润烧伤膏,初期每日换药,首次肉芽长出后隔日一换,直至痊愈。观察并分析3组创面局部症状总积分、愈合性指标(新鲜肉芽出现时间、溃疡愈合时间、疤痕平整率、溃疡感染率、皮肤不良反应率、溃疡面积、溃疡深度)及溃疡危险因素检测指标[踝肱指数(ABI)、下肢经皮氧分压(tcpO2)、震动感觉阈值(VPT)]。结果:治疗后,各组局部症状总积分、溃疡面积、溃疡深度、ABI、tcpO2、VPT均较治疗前显著改善(P<0.01);观察组治疗后局部症状积分、溃疡面积、溃疡深度、新鲜肉芽出现时间、溃疡愈合时间、疤痕平整率、tcpO2、VPT改善情况均显著优于两个对照组(P<0.01,P<0.05)。结论:水动力清创系统联合去腐生新膏治疗下肢难愈性溃疡具有更好的临床效果,能显著改善溃疡局部症状,缩短溃疡愈合时间,缓解溃疡愈合危险因素,安全有效,值得推广应用。