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排序方式: 共有4445条查询结果,搜索用时 15 毫秒
1.
Y.Pazhuhanfar B.Eghbali 《矿物冶金与材料学报》2021,28(6):1080-1089
In the present research, aluminum metal matrix composites were processed by the stir casting technique. The effects of TiB2 rein-forcement particles, severe plastic deformation through accumulative roll bonding (ARB), and aging treatment on the microstructural charac-teristics and mechanical properties were also evaluated. Uniaxial tensile tests and microhardness measurements were conducted, and the micro-structural characteristics were investigated. Notably, the important problems associated with cast samples, including nonuniformity of the rein-forcement particles and high porosity content, were solved through the ARB process. At the initial stage, particle-free zones, as well as particle clusters, were observed on the microstructure of the composite. However, after the ARB process, fracturing phenomena occurred in brittle ceramic particles, followed by breaking down of the fragments into fine particles as the number of rolling cycles increased. Subsequently, com-posites with a uniform distribution of particles were produced. Moreover, the tensile strength and microhardness of the ARB-processed com-posites increased with the increase in the reinforcement mass fraction. However, their ductility exhibited a different trend. With post-deforma-tion aging treatment (T6), the mechanical properties of composites were improved because of the formation of fine Mg2Si precipitates. 相似文献
2.
Parasites of the grey mullet Mugil cephalus collected from Lower K?z?l?rmak Delta in Turkey were investigated. Trichodina puytoraci, Trichodina lepsii, Ligophorus mediterraneus, Ligophorus cephali, Gyrodactylus sp., Microcotyle mugilis, Ascocotyle (Phagicola) longa, Haplosplanchnus pachysomus, Diplostomum spathaceum, Tylodelphys clavata, Posthodiplostomum sp., Neoechinorhyncus agilis and Ergasilus lizae were identified. Overall infection prevalence (%), mean intensity and mean abundance values were 99.61%, 458.10 ± 75.72 and 456.30 ± 75.44, respectively. Infection indices of parasite species in relation to season, lakes/lagoons and some physicochemical parameters of water such as temperature, salinity, dissolved oxygen and nitrate are determined and discussed. Posthodiplostomum sp. is a new parasite record for mugilids and Diplostomum spathaceum is the first record in M. cephalus, in the present study. Moreover, Ligophorus mediterraneus, Ligophorus cephali and Ergasilus lizae are new records for Turkish parasite fauna of fish and Mugil cephalus is a new host record for Neoechinorhyncus agilis in Turkey. 相似文献
3.
This paper presents a new spatial dependence model with an adjustment of feature difference. The model accounts for the spatial autocorrelation in both the outcome variables and residuals. The feature difference adjustment in the model helps to emphasize feature changes across neighboring units, while suppressing unobserved covariates that are present in the same neighborhood. The prediction at a given unit incorporates components that depend on the differences between the values of its main features and those of its neighboring units. In contrast to conventional spatial regression models, our model does not require a comprehensive list of global covariates necessary to estimate the outcome variable at the unit, as common macro-level covariates are differenced away in the regression analysis. Using the real estate market data in Hong Kong, we applied Gibbs sampling to determine the posterior distribution of each model parameter. The result of our empirical analysis confirms that the adjustment of feature difference with an inclusion of the spatial error autocorrelation produces better out-of-sample prediction performance than other conventional spatial dependence models. In addition, our empirical analysis can identify components with more significant contributions. 相似文献
4.
为更好地将专业教育与思政教育有机融合,充分发挥专业课程的育人功能,各学校积极开展课程思政教学改革试点工作,逐步形成"大思政"教育体系。以专业主干课程软件工程为例,在分析教学内容和目标基础上,从科学素养培养、创新意识强化、生活处事哲理灌输等方面阐述了该课程开展课程思政的着眼点,并分别从教学内容设计、教学方法改革和教学评价改进等方面详细分享了开展课程思政的经验和做法。实践表明,上述措施切实加强了学生科学素养、法治素养、民族自信和创新意识的培养,达到了课程思政教育的目的,取得了较为满意的效果。 相似文献
5.
6.
人口老龄化已经成为世界各国、各地区社会经济发展面临的重要问题。中国从2001年步入老龄化社会,提升老龄群体生活质量对于全面实现小康社会意义重大,也是促进中国城镇化健康发展的需要。梳理了中国20世纪80年代以来养老政策和实践的演进路径,强调了居家养老既要符合中国社会经济发展的特征,也要满足老龄群体的生活需求;鉴于中国社区的养老服务设施供给仍然滞后于老龄化发展的现状,探讨了在智慧社会下,通过信息化策略(虚拟空间)与可步行邻里环境(实体空间),提升已有养老服务设施的服务覆盖面和质量、构建老龄群体的智慧社区生活模式、促进居家养老服务的时空匹配、提升居家养老服务的质量水平等策略。 相似文献
7.
正Published online:14 March 2014óScience China Press and Springer-Verlag Berlin Heidelberg 2014Erratum to:Chin.Sci.Bull.(2014)59(5–6):528–532DOI 10.1007/s11434-013-0060-1In the original publication of this paper,the first name and the last name of the first author has been documented 相似文献
8.
Samuel Y.M. Ze‐To 《Journal of forecasting》2015,34(5):379-390
I examine the information content of option‐implied covariance between jumps and diffusive risk in the cross‐sectional variation in future returns. This paper documents that the difference between realized volatility and implied covariance (RV‐ICov) can predict future returns. The results show a significant and negative association of expected return and realized volatility–implied covariance spread in both the portfolio level analysis and cross‐sectional regression study. A trading strategy of buying a portfolio with the lowest RV‐ICov quintile portfolio and selling with the highest one generates positive and significant returns. This RV‐Cov anomaly is robust to controlling for size, book‐to‐market value, liquidity and systematic risk proportion. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
教学质量是教育的核心问题。继续教育的质量保障体系建设,既是继续教育服务学生、服务社会经济发展的必然需求,也是普通高校继续教育发展的自身保障。本文紧扣继续教育质量保障体系建设的工作实践,围绕继续教育现状分析、质量保障体系内涵认知、质量保障体系创建举措与特色等方面进行知行合一的研究论述。 相似文献
10.
基于GIS的通信光缆故障检修保障系统 总被引:2,自引:0,他引:2
光缆一旦发生故障将严重影响正常通信。为了解决光缆故障带来的严重后果,根据光缆网络在地理分布上的空间及环境特征,以地理信息系统(GIS)为基础对光缆及沿线信息实现空间数据库的管理和对故障位置的快速、准确定位,同时给出故障地点及周围的地形地貌等多媒体信息;结合GIS的缓冲区和路径分析功能,搜寻到达光缆故障点的最佳路径,并进一步给出处理故障的应急决策方案。该应用在有效的管理通信光缆资源,缩短抢修时间,减少因故障的发生而带来的损失方面取得了满意的效果。 相似文献