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不枉寻求“推移力”,高效课堂自在行
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作者 郭敏 《学周刊》 2018年第35期118-119,共2页
课堂要高效,方法很重要。教师应巧辟蹊径,根据学情寻找适合课堂的教学方法,寻找能够推动课堂良性发展的一系列"推移力",方能达到"‘课堂高效’自在行"的目的,从而使政治课堂别开生面、别有洞天。文章从主题情境增... 课堂要高效,方法很重要。教师应巧辟蹊径,根据学情寻找适合课堂的教学方法,寻找能够推动课堂良性发展的一系列"推移力",方能达到"‘课堂高效’自在行"的目的,从而使政治课堂别开生面、别有洞天。文章从主题情境增引力、活动课堂添活力、问题导学启智力、他山之石拓能力等四方面入手分析探究。 展开更多
关键词 高中政治 高效课堂 推移力
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倾斜推移体激发颗粒流的连续介质模型 被引量:2
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作者 郭鸿 骆亚生 +2 位作者 程大伟 陈茜 陈栋梁 《中山大学学报(自然科学版)》 CAS CSCD 北大核心 2015年第6期94-98,共5页
岩土工程中的土方推移等属于颗粒体的倾斜推移问题,探索了倾斜推移体在颗粒中平动推移时所受的阻力和升力。应用惯性数的理念,确定了流态类型,提出了适合非准静态流的广义摩擦系数。在此基础上,用基于改进的库伦被动土压力理论,通过基... 岩土工程中的土方推移等属于颗粒体的倾斜推移问题,探索了倾斜推移体在颗粒中平动推移时所受的阻力和升力。应用惯性数的理念,确定了流态类型,提出了适合非准静态流的广义摩擦系数。在此基础上,用基于改进的库伦被动土压力理论,通过基于二维颗粒离散元的位移场分析,建立了预测推移阻力和升力的楔体模型。结果表明,在其他条件相同时,推移阻力不随推移体的倾角变化,但是升力随倾角的增大而显著减小。升力和阻力分别是作用在推移体上合力的竖直分量和水平分量,且阻力和升力的比值为推移体倾角的正切值。广义摩擦角是推移速度和倾角的二次函数。所建立的模型可以预测不同倾角和推移速度时推移阻力和升力的大小。 展开更多
关键词 推移和升 改进库伦模型 颗粒介质 倾斜平板
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渭河下游蜿蜒型河道的河相关系 被引量:2
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作者 熊国立 《水利学报》 EI CSCD 北大核心 1995年第1期63-68,共6页
选用正弦曲线的河床形态作为原生的河相关系式,与水流连续性等方程联解,导出蜿蜒型河道的河相关系式.
关键词 渭河下游 蜿蜒型 河相 正弦曲线 推移力
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语文学法断想
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作者 刘惠民 高立鹤 《鄂西大学学报(社会科学版)》 1989年第2期37-40,共4页
古人说:“大匠与人规矩,不能使人巧”。怎样才能达到“巧”的境界呢,单靠“教”是不行的,还必须发挥“学”的积极性和创造性,这有个很重要的学法问题。作为各门学科基础的语文学科的教学更是如此。本文即是笔者在教学实践中对于语文学... 古人说:“大匠与人规矩,不能使人巧”。怎样才能达到“巧”的境界呢,单靠“教”是不行的,还必须发挥“学”的积极性和创造性,这有个很重要的学法问题。作为各门学科基础的语文学科的教学更是如此。本文即是笔者在教学实践中对于语文学法的一些原则的思考,零零散散,不成系统,姑名之曰“断想”。 展开更多
关键词 语文学法 中国语文 习语 语文学习 目标意识 推移力 边光 学习过程 认字率 语文学科
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Non-capacity transport of non-uniform bed load sediment in alluvial rivers 被引量:7
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作者 CAO Zhi-xian HU Peng +1 位作者 PENDER Gareth LIU Huai-han 《Journal of Mountain Science》 SCIE CSCD 2016年第3期377-396,共20页
Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity... Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sedim ent inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, non-capacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated. 展开更多
关键词 Fluvial process Sediment transport Bed deformation Non-uniform bed load Capacity transport
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关于风化花岗岩荒山产沙量的计算
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作者 木本秋津 内田太郎 +1 位作者 水山高久 李昌华 《水土保持科技情报》 2000年第3期23-26,共4页
计算水土流失量,现有多种计算模式,但多为经验公式。对于观测资料较少的山地小流域的应用,其计算值偏大,不能反映客观事实。通过对小流域降雨量、径流量、产沙量的观测,应用多个模式计算,以计算值与实测值比较,得出结论:水土流... 计算水土流失量,现有多种计算模式,但多为经验公式。对于观测资料较少的山地小流域的应用,其计算值偏大,不能反映客观事实。通过对小流域降雨量、径流量、产沙量的观测,应用多个模式计算,以计算值与实测值比较,得出结论:水土流失量不取决于推移质拖曳力,而是泥沙供给量的函数。水土流失率、地表可蚀性不取决于降雨规模,若以土壤紧实度等因子表示地表土壤状态,则能够再现流域产沙量。 展开更多
关键词 水土流失 产沙量 推移质拖曳 荒山 流域
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Numerical Analysis of Adaptation-to-capacity Length for Fluvial Sediment Transport 被引量:1
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作者 LI Zhi-jing CAO Zhi-xian +1 位作者 Gareth PENDER HU Peng 《Journal of Mountain Science》 SCIE CSCD 2014年第6期1491-1498,共8页
Over the last several decades,various sediment transport capacity formulations have been used by geomorphologists and engineers to calculate fluvial morphological changes.However,it remains poorly understood if the ad... Over the last several decades,various sediment transport capacity formulations have been used by geomorphologists and engineers to calculate fluvial morphological changes.However,it remains poorly understood if the adaptation to capacity could be fulfilled instantly in response to differing inflow discharges and sediment supplies,and thus if the calculation of morphological changes in rivers based on the assumed capacity status is fully justified.Here we present a numerical investigation on this issue.The distance required for sediment transport to adapt to capacity(i.e.,adaptation-to-capacity length) of both bed load and suspended sediment transport is computationally studied using a coupled shallow water hydrodynamic model,in line with varied inlet sediment concentrations.It is found that the adaptation-to-capacity length generally decreases as the Rouse number increases,irrespective of whether the inlet sediment concentration increases or reduces.For cases with vanishing inlet sediment concentration a unified relationship is found between the adaptation-to-capacity length and the Rouse number.Quantitatively,the adaptation-to-capacity length of bed load sediment is limited to tens of times of the flow depth,whilst that of suspended sediment increases substantially with decreasing Rouse number and can be up to hundreds of times of the flow depth.The present finding concurs that bed load sediment transport can adapt to capacity much more rapidly than suspended sediment transport,and it facilitates a quantitative criterion on which the applicability of bed load or suspended sediment transport capacity for natural rivers can be readily assessed. 展开更多
关键词 Sediment transport Sediment transport capacity Mathematical river modeling Bed load Suspended load
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Developing a 2D vertical flow and sediment transport model for open channels using the Youngs-VOF method
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作者 赵东淼 唐军 +3 位作者 吴修广 林昌宁 刘丽君 陈剑 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2017年第2期444-451,共8页
A 2D vertical (2DV) numerical model, without o-coordinate transformation in the vertical direction, is developed for the simulation of flow and sediment transport in open channels. In the model, time-averaged Reynol... A 2D vertical (2DV) numerical model, without o-coordinate transformation in the vertical direction, is developed for the simulation of flow and sediment transport in open channels. In the model, time-averaged Reynolds equations are closed by the k-e nonlinear turbulence model. The modified Youngs- VOF method is introduced to capture free surface dynamics, and the free surface slope is simulated using the ELVIRA method. Based on the power-law scheme, the k-e model and the suspended-load transport model are solved numerically with an implicit scheme applied in the vertical plane and an explicit scheme applied in the horizontal plane. Bedload transport is modeled using the Euler-WENO scheme, and the grid-closing skill is adopted to deal with the moving channel bed boundary. Verification of the model using laboratory data shows that the model is able to adequately simulate flow and sediment transport in open channels, and is a good starting point for the study of sediment transport dynamics in strong nonlinear flow scenarios. 展开更多
关键词 sediment transport 2D vertical model Youngs-VOF Euler-WENO bed evolution
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观书有感二首 被引量:1
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作者 朱熹 《群言》 1997年第2期35-35,共1页
关键词 朱熹 推移力 福建尤溪 诗义 天光 书院 中流 水生 自在 南溪
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擂鼓助阵话“三讲”
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作者 刘难先 《内蒙古宣传思想文化工作》 1999年第3期4-5,共2页
关键词 “讲政治” 推移力 以美国为首的北约 党的三代领导集体 政治工作 浩然正气 政治理论 “讲学习” 各方面的积极性 政治是经济的集中表现
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