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从教具制作、定量实验探究和教学启示等三方面来探究匀速圆周运动的向心加速度公式,即利用自制教具探究向心加速度a c与圆周运动半径r和角速度ω之间的定量关系.实验发现,结果非常好地符合理论预期.最后讨论了该教具所蕴含的教学启示,可以将其设计成适合高中物理教学的验证性、探究性实验及课外科创活动,从而培养学生的科学探究能力、科学推理能力、动手协作能力和问题解决能力.本教具还提供了测量当地重力加速度的一种新方法.  相似文献   
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While macroscopic longitudinal and transverse dispersion in three-dimensional porous media has been simulated previously mostly under purely advective conditions, the impact of diffusion on macroscopic dispersion in 3D remains an open question. Furthermore, both in 2D and 3D, recurring difficulties have been encountered due to computer limitation or analytical approximation. In this work, we use the Lagrangian velocity covariance function and the temporal derivative of second-order moments to study the influence of diffusion on dispersion in highly heterogeneous 2D and 3D porous media. The first approach characterizes the correlation between the values of Eulerian velocity components sampled by particles undergoing diffusion at two times. The second approach allows the estimation of dispersion coefficients and the analysis of their behaviours as functions of diffusion. These two approaches allowed us to reach new results. The influence of diffusion on dispersion seems to be globally similar between highly heterogeneous 2D and 3D porous media. Diffusion induces a decrease in the dispersion in the direction parallel to the flow direction and an increase in the dispersion in the direction perpendicular to the flow direction. However, the amplification of these two effects with the permeability variance is clearly different between 2D and 3D. For the direction parallel to the flow direction, the amplification is more important in 3D than in 2D. It is reversed in the direction perpendicular to the flow direction.  相似文献   
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Mung J  Han S  Yen JT 《Ultrasonics》2011,51(6):768-775
Interventional surgical instrument localization is a crucial component of minimally invasive surgery. Image guided surgery researchers are investigating devices broadly categorized as surgical localizers to provide real-time information on the instrument’s 3D location and orientation only. This paper describes the implementation and in vitro evaluation of a prototype real-time nonimaging ultrasound-based catheter localizer system towards use in abdominal aortic aneurysm procedures. The catheter-tip is equipped with a single element ultrasound transducer which is tracked with an array of seven external single element transducers. The performance of the system was evaluated in a water tank and additionally in the presence of pork belly tissue and also a nitinol-dacron stent graft. The mean root mean square errors were respectively 1.94 ± 0.06, 2.54 ± 0.31 and 3.33 ± 0.06 mm. In addition, this paper illustrates errors induced by transducer aperture size and suggests a method for aperture error compensation. Aperture compensation applied to the same experimental data yielded mean root mean square errors of 1.05 ± 0.07, 2.42 ± 0.33 and 3.23 ± 0.07 mm respectively for water; water and pork; and water, pork and stent experiments. Lastly, this paper presents a video showing free-hand movement of the catheter within the water tank with data capture at 25 frames per second.  相似文献   
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利用软件模拟的物理建模方法,以考虑阻力的斜抛运动为例,首先用Tracker视频分析软件对抛体运动进行视频记录,然后利用Python编程软件进行场景模拟和建模分析,经过多次修正建立较准确的有阻力斜抛运动模型.本方法实验简便,低成本,可推广到其他动力学运动实验中。  相似文献   
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葛兴烁  李强 《物理通报》2021,(3):111-113
信息技术与物理课堂教学有效整合,将会更好地实现高效课堂.物理开源Tracker视频分析软件,能够较为准确地追踪物体的运动情况,并直观反映物体运动轨迹和运动特点,进而帮助学生更好地理解运动规律,提高教学效率.  相似文献   
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设计了基于Tracker软件研究竖直方向阻尼振动的居家实验.选用橡皮筋和水果自制振子模型,利用Tracker软件对自制橡皮筋振子的阻尼振动进行研究,绘制橡皮筋振子模型在竖直方向上做阻尼振动的“y t”图像,并通过数据拟合,计算出该阻尼振动的振幅、周期、圆频率、阻尼系数等,是利用生活物品进行大学物理实验的一次尝试.  相似文献   
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2D numerical simulations of tidal bores were obtained using the OpenFOAM CFD software to solve the Navier–Stokes equations by means of the Finite Volume Method by applying a LES turbulence model. The trajectories of non-cohesive sediment particles beneath tidal bores were estimated using a tracker method. Using the fourth order Runge–Kutta scheme, the tracker method solves the Maxey and Riley equations, which requires the knowledge of the velocity field at time t. From 2D numerical simulations of tidal bores, we proposed a classification of tidal bores with respect to the Froude number Fr (or r the ratio of water depths). For a Froude number 1<Fr<1.43 (1<r<1.57), the tidal bore is undular. For a Froude number 1.43<Fr<1.57 (1.57<r<1.75), the tidal bore is partially breaking, which is similar to the transitional tidal bore defined by Furgerot (2014). And for a Froude number Fr>1.57 (r>1.75), the tidal bore is totally breaking. The numerical results of trajectories of non-cohesive sediment particles are similar to the type of trajectories given by the analytical model proposed by Chen et al. (2012) with some modifications to take into account the effects of gravity, elevation, and attenuation. The parameters of modified Chen's model, β1, β2 and β3, are linearly proportional to the Froude number Fr. This is because the level of turbulence for undular tidal bores is low. The flow induced by an undular tidal bore is not complex. This physical phenomenon is quasi linear. The parameter β1, related to the front celerity of the undular tidal bore, decreases when the Froude number Fr increases. The parameter β2, related to the elevation, increases when the Froude number Fr increases. And the parameter β3, related to the attenuation of the secondary waves, increases when the Froude number Fr increases.  相似文献   
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