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排序方式: 共有397条查询结果,搜索用时 119 毫秒
1.
In this paper, we introduce a new type of troubled-cell indicator to improve
hybrid weighted essentially non-oscillatory (WENO) schemes for solving the hyperbolic conservation laws. The hybrid WENO schemes selectively adopt the high-order
linear upwind scheme or the WENO scheme to avoid the local characteristic decompositions and calculations of the nonlinear weights in smooth regions. Therefore,
they can reduce computational cost while maintaining non-oscillatory properties in
non-smooth regions. Reliable troubled-cell indicators are essential for efficient hybrid
WENO methods. Most of troubled-cell indicators require proper parameters to detect
discontinuities precisely, but it is very difficult to determine the parameters automatically. We develop a new troubled-cell indicator derived from the mean value theorem
that does not require any variable parameters. Additionally, we investigate the characteristics of indicator variable; one of the conserved properties or the entropy is considered as indicator variable. Detailed numerical tests for 1D and 2D Euler equations are
conducted to demonstrate the performance of the proposed indicator. The results with
the proposed troubled-cell indicator are in good agreement with pure WENO schemes.
Also the new indicator has advantages in the computational cost compared with the
other indicators. 相似文献
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目的评估锁定钢板固定股骨干骨折时不同螺钉布局对股骨干骨折内固定系统稳定性的影响,为股骨干骨折内固定系统螺钉布局的临床研究提供指导。方法针对4组螺钉的3个参数化水平进行正交试验方案设计,分别对9组不同螺钉布局的股骨干骨折内固定系统进行生物力学有限元分析,得出各组试验的4项考察指标:接骨板最大等效应力、螺钉最大等效应力、股骨最大等效应力及内固定系统最大轴向位移,并利用权矩阵分析方法进行正交试验数据分析。结果不同组别螺钉参数对内固定系统稳定性的影响权重不同,4组螺钉参数中对内固定系统稳定性影响的最大权重分别为13.86%、7.57%、7.53%及5.91%。结论正交试验中螺钉布局的最佳方案为第1组螺纹孔不固定螺钉,第2组螺纹孔固定单皮质螺钉,第3、4组螺纹孔固定双皮质螺钉。 相似文献
4.
An Explicit MUSCL Scheme on Staggered Grids with Kinetic-Like Fluxes for the Barotropic and Full Euler System 下载免费PDF全文
Thierry Goudon Julie Llobell & Sebastian Minjeaud 《Communications In Computational Physics》2020,27(3):672-724
We present a second order scheme for the barotropic and full Euler equations. The scheme works on staggered grids, with numerical unknowns stored at dual locations, while the numerical fluxes are derived in the spirit of kinetic schemes. We identify stability conditions ensuring the positivity of the discrete density and energy. We illustrate the ability of the scheme to capture the structure of complex flows with 1D and 2D simulations on MAC grids. 相似文献
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8.
Ning Zhang Cuifang Hao Xiaoyan Liu Shouxin Zhang Fengrong Zhang Lili Zhuang 《Gynecological endocrinology》2017,33(2):113-118
Objective: To identify the quantitative profiling of adiponectin and its receptors (AdipoR1, AdipoR2, and T-cadherin) in cumulus cells (CCs) and to evaluate their roles in the early embryo development of polycystic ovary syndrome (PCOS) patients, in part, with obesity.Methods: Fifty-five subjects were divided into two groups according to the body mass index. Oocytes were further inseminated and only mature and normal fertilized oocytes (2PN) were included in this research. Real-time PCR and western blot were performed to identify adiponectin and its receptors in CCs.Results: Adiponectin and receptors were ubiquitously expressed in CCs of PCOS and non-PCOS patients. The level of AdipoR2 in CCs from the oocytes yielding blastocyst after 5/6 days in vitro culture was markedly higher than in those from oocytes could not develop to blastocyst stage after Day 6, for non-obese or obese PCOS patients (0.1647?±?0.0161 versus 0.0783?±?0.0385, 0.1948?±?0.0307 versus 0.1057?±?0.0236, respectively, p?0.05). In addition, only in patients with PCOS and concurrent obesity the AdipoR1 in CCs was considerably increased in CC-B+ compared with CC-B? subgroup (0.5162?±?0.0371 versus 0.2448?±?0.0333, p?0.01).Conclusion: The development of early embryo was associated with the up-regulation of AdipoR1 and AdipoR2 in PCOS patients. Our results suggested that adiponectin could positively modulate embryo development in humans. Further investigations should be carried out to unlock the crucial role that adiponectin plays in embryo development. 相似文献
9.
《Systems biology in reproductive medicine》2013,59(5):277-285
AbstractDNA damage in cumulus cells (CCs) might be related with the developmental competence of the enclosed oocytes, however, conclusive studies are missing, partially due to the lack of a reliable, cheap, fast, and reproducible DNA damage test. We report the development of a chromatin dispersion test that allows for a fast evaluation of double strand DNA (ds-DNA) damage in CCs. The whole experiment was performed using CCs from 103 oocyte retrieval cycles evaluating the prototype D3-MAX ability (a chromatin dispersion based assay) to detect DNA breaks against in situ nick translation (ISNT) and a two tailed comet assay (TT-comet). Samples were collected from women younger than 35 years of age with a good response to stimulation. Pooled cumulus cells of MII oocytes were used. The chromatin dispersion assay results correlate with the double strand-DNA breaks values assessed by the TT-comet assay (Spearman Rho?=?0.624; p?=?0.003;), while the correlation was poor when compared to the single strand DNA (ss-DNA) breaks observed also with the TT-comet assay (Spearman Rho?=??0.141; p?=?0.554). ISNT showed a correspondence in the same cells between enzymatic incorporation of modified nucleotides and halos of chromatin dispersion. We conclude that D3-Max test detects mainly ds-DNA breaks in cumulus cells and is a reliable, fast, and easy reproducible assay suitable for routine clinical practices once the influence on oocyte quality has been established. 相似文献
10.
Two differently-produced open-cell aluminum foams were compared to a commercially available finned heat sink. Further, an aluminum plate and block were tested as a reference. All heat sinks have the same base plate dimensions of four by six inches. The first foam was made by investment casting of a polyurethane preform and has a porosity of 0.946 and a pore density of 10 pores per linear inch. The second foam is manufactured by casting over a solvable core and has a porosity of 0.85 and a pore density of 2.5 pores per linear inch. The effects of orientation and radiative heat transfer are experimentally investigated. The heat sinks are tested in a vertical and horizontal orientation. The effect of radiative heat transfer is investigated by comparing a painted/anodized heat sink with an untreated one. The heat flux through the heat sink for a certain temperature difference between the environment and the heat sink’s base plate is used as the performance indicator. For temperature differences larger than 30 °C, the finned heat sink outperforms the in-house-made aluminum foam heat sink on average by 17%. Furthermore, the in-house-made aluminum foam dissipates on average 12% less heat than the other aluminum foam for a temperature difference larger than 40 °C. By painting/anodizing the heat sinks, the heat transfer rate increased on average by 10% to 50%. Finally, the thermal performance of the horizontal in-house-made aluminum foam heat sink is up to 18% larger than the one of the vertical aluminum foam heat sink. 相似文献