共查询到19条相似文献,搜索用时 62 毫秒
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以"机械效率"一课为例,通过典型例题的分析与建模来说明在教学中如何通过构建物理模型来攻克机械效率这一教学难点. 相似文献
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近几年物理高考题中,部分考试题型的物理情景设计是源于生产生活实际素材,源于实验所取得数据。学生遇到这类题型,往往不知道如何着手。本文针对这个问题阐述了物理模型建构的意义,归纳了建模方法以及物理模型建构与应用,对学生学习物理、培养兴趣具有一定的意义。 相似文献
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研究了粉末材料堆积过程仿真的物理模型和系统,并探讨了适合多种不同粒径颗粒混合堆积过程仿真的高性能计算方法.在该仿真系统中,考虑了重力、接触力、阻尼力、摩擦力和范德瓦耳斯力等多种作用力的影响,集成了多种接触力模型和阻尼模型,使其适用于三维大规模粉末材料堆积过程的计算机仿真.利用该系统对粉末材料领域中的两个典型应用进行了模拟研究.模拟了两种相同密度不同粒径颗粒(粒径比为10)的混合堆积过程.当小颗粒数为大颗粒数的300倍时,得到最大的堆积密度(体积分数)为0.82.另外,还模拟了两种不同密度相同粒径颗粒的混合堆积过程.当堆积结束时,出现了明显的分离(segregation)现象和团聚现象.所研究的物理模型和仿真系统既可用于粉末材料堆积过程研究,亦可用于普通的球形物体堆积过程的模拟研究.
关键词:
粉末堆积
物理模型
仿真系统
离散元法 相似文献
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针对以往光学图像加密系统中输入面和频谱面对称性的缺点,在不增加系统元件的基础上,利用球面波照射不对称非标准傅里叶变换系统进行图像加密。通过把相位掩模置于该系统的傅里叶变换平面,利用不对称非标准傅里叶变换系统的输入面和频谱面的不对称性以及频谱面对于点光源相关参数的依赖性,克服了以前光学加密系统中输入面和频谱面的对称性所带来的安全隐患,并且获得了除相位掩模以外的另外四重密匙。理论分析和模拟实验表明:该方法不仅可行,而且多增加了几重密匙,增强了系统的安全性能。 相似文献
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An enhanced asymmetric cryptosystem for color image is proposed by using equal modulus decomposition (EMD) in the gyrator transform domains. In this scheme, the EMD is performed to create the effective trapdoor one-way function. Moreover, to enhance the security of the cryptosystem, the Baker mapping is considered and utilized for scrambling the RGB components of the color image. The parameters in the Baker mapping and gyrator transform can be served as the extra keys of the entire cryptosystem. Various types of attacks are considered in the robustness analysis experiments. Some numerical simulations are made to verify the validity and capability of the proposed color encryption algorithm. 相似文献
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By means of a new Monte Carlo sampling of a grand canonical ensemble, we verify universality for the critical exponents and of two models of lattice trees constrained to be self-avoiding on sites or on bonds. The attrition constants are also obtained. This algorithm, a generalization of that recently proposed by Berretti and Sokal for random walks, appears to optimize the critical slowing down in the scaling region. Systematic and statistical errors are carefully estimated. 相似文献
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非嵌入式随机多项式展开法是目前性能最优的一种不确定声场快速算法,但配点的选择对算法计算精度影响较大,且当计算随不确定海洋环境参数变化剧烈的声场输出时,需采用分段概率配点法等特殊方法处理。基于Kriging模型提出了一种新的浅海不确定声场快速算法,首先给出了该算法的理论推导,然后通过数值计算验证了算法性能,并给出具体的物理解释,结果表明:在同等条件下,新算法的计算精度较非嵌入式随机多项式展开法更高;无需针对声场输出随不确定海洋环境参数的变化情况采取特殊处理过程;克服了非嵌入式随机多项式展开法为提高计算精度将随机多项式展开至非常高的阶数,从而增加计算量的不足;较非嵌入式随机多项式展开法,其样本点的选择简单易行,且可直接计算误差,因此,本文算法较非嵌入式随机多项式展开法普适性更强。 相似文献
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以蒙特卡罗模拟方法对自对耦分布二维随机链q态Potts模型的短时临界行为进行了数值研究.利用初始非平衡演化阶段存在的普适幂指数和有限体积标度行为,数值模拟了在不同形式随机分布时q=3和q=8态Potts模型磁临界指数η和动力学临界指数z.计算结果发现η不依赖于自对偶无序分布的具体形式, 从而以数值方法给出了一个关于淬火掺杂自旋系统的临界普适行为的验证.
关键词:
随机链Potts模型
动力学蒙特卡罗模拟
临界普适性 相似文献
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A quantum identification scheme including registration and identification phases is proposed. The users‘ passwords are transmitted by qubit string and recorded as a set of quantum operators. The security of the proposed scheme is guaranteed by the no-cloning theorem. Based on photon polarization modulation, an experimental approach is also designed to implement our proposed scheme. 相似文献
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Explicit solutions are derived for some nonlinear physical model equations by using a delicate way of two-step ansatz method. 相似文献
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A new cryptosystem based on spatial chaotic system 总被引:1,自引:0,他引:1
Encryption of images is different from that of texts due to some intrinsic features of images such as bulk data capacity and high redundancy, which is generally difficult to handle by traditional methods. This paper proposes a new spatial chaos system (SCS), which is investigated by conducting FIPS 140-1 statistic test, and is especially useful for encryption of digital images. It is shown how to adapt a two dimensional (2D) ergodic matrix obtained from SCS to permute the positions of image pixels and confuse the relationship between the cipher image and plain image simultaneously. Experimental results show that the performance and security of the proposed cryptographic system are better than those of existing lower dimensional chaotic cryptographic systems. 相似文献
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