排序方式: 共有12条查询结果,搜索用时 15 毫秒
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在一拥有辐射环状交通网络的城市工作区内,使用小车上下班的职员在通勤时的平均移动距离约为多少?本文基于一个较现实的模型对此进行了理论上的解析,所得结果,从城市规划的观点来看,具有一定的实际意义。 相似文献
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关于圆形和方形城市工作区道路交通面积的解析与比较 总被引:1,自引:1,他引:0
对于城市规划来讲,事先预测其工作区内所需道路面积,以尽量避免实际交通网络中发生拥挤阻塞,具有重要意义,在本文,我们通过考虑一个城市通勤高峰时期的车辆交通情况,并通过利用走行中的车辆占用道路面积这一概念,基于一个相对现实的模型,从理论上对圆形方形城市工作区推导了所需的道路面积,并将两者加以比较,以发现与其交通网络结构相关的工作区的相对有效形状。 相似文献
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采用Riemann-Liouville分数阶导数,研究了半正的分数阶微分方程(n-1,1)-型积分边值问题,获得了参数λ的一个区间,使得λ落在这个区间的时候,该半正的分数阶微分方程边值问题有多个正解. 相似文献
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SPCP是一项关于以评估城市内部道路交通网络各段拥挤度,来反映相应道路在该城市道路网中所占重要程度的研究.在通过对于包括东京在内的日本一些城市的应用,其实用性已得到了广泛验证.本论文从理论上揭示了SPCP所近似反映的一种城市交通模式,从而为其为何能够在现实城市中被应用提供了理论性依据.此外在本文中,基于被展示的城市交通模型和SPCP,我们还推导计算出了一项经常用于衡量城市道路交通有效性的尺度-城市内道路交通移动所需平均距离. 相似文献
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We propose an experimental scheme of using the far-off resonance optical dipole force to control tunable collapse of Bose-Einstein condensation with attractive interactions. This scheme can conveniently alter collapse phenomena while keeping interatomic processes unchanged. Effects on the critical interaction strength and time delay are studied with numerical simulation. We show that for the blue-detuning case those two quantities are increased while for the red-detuning case they are decreased. 相似文献
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板材多点成形过程的有限元分析 总被引:8,自引:0,他引:8
多点成形过程采用静力隐式格式进行数值模拟是比较合适的。本文建立了用于多点成形过程分析的静力隐式弹塑性大变形有限元方法 ,给出了对稳定迭代收敛过程效果较好的板壳有限单元模型、处理多点不连续接触边界的接触单元方法以及增量变形过程中应力及塑性应变计算的多步回映计算方法。基于这些方法编制了计算软件 ,应用该软件进行了矩形板的液压胀形过程及球形模具拉伸成形过程的有限元分析 ,数值计算结果与典型的实验结果及计算结果吻合很好。最后给出了球形、圆柱形目标形状的实际多点成形过程的数值模拟结果。 相似文献
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The original mimetic model was proposed to take the role of dark matter. In this paper we consider possible direct interactions of mimetic dark matter with other matter in the universe, especially standard model particles such as baryons and photons. By imposing shift symmetry, the mimetic dark matter field can only have derivative couplings. We discuss the possibilities of generating baryon number asymmetry and cosmic birefringence in the universe based on the derivative couplings of mimetic dark matter to baryons and photons. 相似文献
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In recent years there has been a lot of interest in discussing frame dependences/independences of the cosmological perturbations under the conformal transformations. This problem has previously been investigated in terms of the covariant approach for a single component universe, and it was found that the covariant approach is very powerful to pick out the perturbative variables which are both gauge and conformal invariant. In this work, we extend the covariant approach to a universe with multicomponent fluids. We find that similar results can be derived,as expected. In addition, some other interesting perturbations are also identified to be conformal invariant, such as entropy perturbation between two different components. 相似文献