应用简谐运动加速度的对称性解题

物体做简谐运动的过程中，在关于平衡位置对称的位置，各个物理量的大小相等．图1所示，弹簧振子在A，B点时的加速度等大反向，任意一对对称点都符合此规律。     

细胞神经网络的数学理论(Ⅰ)

重新系统地研究了细胞神经网络的数学理论,涉及该网络的耗散性、平衡位置的数目及表示、平衡态的全局稳定性等。     

从一道题的错解说弹簧振子

本文对一道高考模拟试卷中引发热议的多项选择题做了详细的分析和深入的讨论.本期同时发表的还有陆天明老师的《对一道双平衡位置振动问题的讨论》.二文各有千秋.     

原型启发在解题中的应用

 当人研究某个问题,突然在某一事物的启发下,引起相似性或相关性的联想,进发出创造性的新设想,从而使问题得到顺利解决。这种从其他相似性或相关性事物中得到启示,进发灵感的方法称为原型启发。能够起到启发作用的事物叫做原型。     

Dust Particle Properties in a Dual-Frequency Driven Sheath

We study characteristics of a single dust particle in a duai-frequency capacitively coupled plasma sheath, such as charging and suspending processes, using a collisionless self-consistent model. Also, the movement of the dust grain with time is investigated for the various radii and initial velocities. The numerical results show that, after several microseconds, the charging process of the dust particle reaches equilibrium, and the grain obtains its equilibrium position, In addition, it is found that the parameters of the low-frequency source impact on the charging and suspending processes of the dust grain significantly.     

单摆摆球运动轨迹控制装置

设计了单摆摆球运动轨迹控制装置,该装置由摆线指针、摆线定位板组成.使用控制装置可以准确、快速调节单摆的平衡位置和摆动角度,保证摆球在平行于角度尺的铅垂平面内运动.     

肥皂泡中的科学初探

 提起肥皂泡,每个人都会联想起自己的童年时光,一件孩童的玩物,当我们在欣赏它的独特形状和奇异色彩时,是否曾惊叹这样一个五彩缤纷的东西竟被我们那样容易地吹了出来。也许你不相信,一个肥皂泡所包含的内容,是远远超过一个只是吹吹玩的人的想象的。1889年底到1890年初,伦敦物理学会主席C.V.波易斯曾分3次为伦敦的青少年做过有关肥皂泡的演讲,而在其前后,更有许多科学家做过有关肥皂泡的研究:如科学巨匠达·芬奇,物理学家牛顿、胡克、托马斯·扬、瑞利、吉布斯和朗缪尔,数学家高斯、拉普拉斯和泊松等。小小的肥皂泡究竟有多少诱人的秘密,让这么多人去研究它?     

线性振子过阻尼特性分析

分析了线性振子的过阻尼特性,指出处于过阻尼状态的线性振子在特定初始条件下能越过平衡位置一次,在另一特定初始条件下,振子将能最快地回到平衡位置。     

非线性机械悬置的超声辐射力测量装置

文章报道了一种能测量几十毫瓦数量级声功率的声辐射力测量系统,其辐射力靶(或浮体)的悬置机构具有非线性响应。该系统的两种悬置方案如图1(a)和1(b)所示。为使浮体在柱对称的声场中自动定位,它具有一种倒锥表面,在悬浮液中承受中性的或正的浮力,这样可以零位移为标志,测量使浮体保持在平衡位置所需的抵消辐射力的力。在每种设计方案中,浮体都是用三对无弹性轻绳支撑的,三对绳对浮体轮缘呈120°的间距,每一对绳的两根由一小环相连,小环上悬挂有一小砝码。在平衡位置,每对绳中的一根是铅垂的,而另一根是水平的。     

Orientations of special water dipoles that accelerate water molecules exiting from carbon nanotube

One-dimensional ordered water molecules entering and exiting from a carbon nanotube with an appropriate radius are studied with molecular dynamics simulations. It can be found that a water molecule near the nanotube end is more likely to be expelled from the nanotube if its dipole is almost perpendicular to the nanotube axis. The key to this observation is that those water molecules are closer to the wall of the nanotube away from the equilibrium position of the Lennar-Jones (LJ) potential. Thus, the interaction energy for those water molecules is relatively high. There are two particular structures of the perpendicular water molecule depending on the dipole direction of the adjacent water molecule in the nanotube. Although the probabilities of these structures are quite small, their contributions to the net flux across the nanotube end are approximately equal to the predominant structures. The present findings further show the possibility of controlling the water flow by regulating the dipole directions of the water molecules inside the nanochannels.