多功能音乐沙漏的设计与实现

为更加有效地反映时间的流逝,设计了电子沙漏电路,利用控制灯珠的亮灭来模拟沙漏中沙子的掉落。在非整点时,电子沙漏电路会模拟30秒正常的沙漏掉落,以提醒人们时间的可贵,要珍惜碎片化的时间;在整点时刻,电子沙漏电路将进行短暂的时间回溯,下部沙粒重回上部沙漏后再次掉落,同时播放歌曲并且灯珠颜色变化,此过程同为30秒,以此提醒人们时间一去不回,人们应当注重时间管理,好好利用时间。     

沙漏计时原理二维数值模拟

提出沙漏计时二维数值模型,并用元胞自动机的方法对该模型进行计算机模拟.结果表明由于开口处沙粒的流动而引起的沙堆崩塌行为是一个准周期性振荡过程,开口大小与崩塌总时间近似成线性关系.特殊的开口位置会引起崩塌"拍",且随沙堆高度呈周期性变化.     

沙漏超重和失重的数字化实验研究

沙漏是一种常见的计时与装饰仪器.在沙子下落过程中,沙漏受力情况会发生复杂的变化.这里结合牛顿运动定律完整地分析沙子处于沙漏上端静止、下落、空中下降、撞击、下端静止等5个阶段的运动情况.我们通过自制简易装置,并利用Vernier LabPro传感器较好地观测到沙子下落的整个阶段,而且所测数据与理论分析相一致.     

时间的沙漏

时间是什么? 它是无限的还是轮回的? 是没有开始的还是起源于一次大爆炸? 是一维的还是半维的?是实数还是虚数?该取实数值还是整数值? 是参数还是变量?所有这些关于时间的模棱两可的认识都表明物理学需要一个角色普适的时间.     

有限元程序网格沙漏变形的分析与控制

分析二维拉氏四边形四节点等参有限元程序存在的网格沙漏变形问题,认为单元刚度矩阵的秩缺陷是沙漏变形的原因,给出一种消除单元刚度矩阵秩缺陷且正交于线性位移场的沙漏控制方法,不仅有效地控制了沙漏变形,而且通过了分片检验.把此种沙漏粘性加入程序后计算多种算例,证明了此控制方法的有效性.     

对几个物理学名词的修改意见（续）

4time translation：时间平移-时间迁移 英语translation的本意是转移和迁移．现在在数学名词和物理学名词里定为“平移”，指的是在空间中不带转动的平行移动．但是时问只有一维，何来平动和转动的分别？所以“时间平移”的说法就不对了．因此建议改为“时间迁移”．     

一维时间周期势的量子隧穿

研究了一维时间周期势的量子隧穿,建立了周期势的两种物理模型,并分别在不同情况下对其进行理论研究和推导,证明了一维周期势下的量子隧穿可统一由一种模型处理.     

Larmor time and proper time

The idea of a Larmor clock is reexamined in the relativistic regime. We propose a concept of proper time for quantum theoretical particles. The Larmor clock can measure, under some relevant conditions, the proper time that passes while the particle stays in a space region. Our approach to Larmor clock is different than those of other researchers in the following two aspects: our concept of Larmor clock does not distinguish whether the particle is transmitted or reflected at the end of its stay, and pointer of our Larmor clock is not the spin but the total angular momentum.     

The case of escape probability as linear in short time

We derive rigorously the short-time escape probability of a quantum particle from its compactly supported initial state, which has a discontinuous derivative at the boundary of the support. We show that this probability is linear in time, which seems to be a new result. The novelty of our calculation is the inclusion of the boundary layer of the propagated wave function formed outside the initial support. This result has applications to the decay law of the particle, to the Zeno behaviour, quantum absorption, time of arrival, quantum measurements, and more.     

First passage time and escape time distributions for continuous time random walks

We consider an arbitrary continuous time random walk (ctrw)via unbiased nearest-neighbour jumps on a linear lattice. Solutions are presented for the distributions of the first passage time and the time of escape from a bounded region. A simple relation between the conditional probability function and the first passage time distribution is analysed. So is the structure of the relation between the characteristic functions of the first passage time and escape time distributions. The mean first passage time is shown to diverge for all (unbiased)ctrw’s. The divergence of the mean escape time is related to that of the mean time between jumps. A class ofctrw’s displaying a self-similar clustering behaviour in time is considered. The exponent characterising the divergence of the mean escape time is shown to be (1−H), whereH(0<H<1) is the fractal dimensionality of thectrw.     

The reverberation time of furnished rooms in dwellings

The study gives the results of the measurements of the reverberation time in 11,687 rooms, of which 11,457 are furnished (8246 bedrooms, 3211 living rooms) and 230 unfurnished. All the rooms have heavy walls and ceilings, and a heavy floor covering. The reverberation times measured are quite similar in bedrooms and living rooms within the same size range, and decrease fairly uniformly as the frequency increases. Moreover, in each frequency band the greater the volume of the room, the greater the reverberation time.The results of this extensive fieldwork allow us to predict accurately the reverberation time in these kinds of spaces as a function of their size and the frequency. These data may be useful for improving the accuracy of calculations models to estimate the reverberation time of enclosed spaces. A comparison between the reverberation time measured in this work and that proposed in PrEN ISO 10052.2002(E) has been made.     

The time arrow in a Planck gas

In this paper the quantum heat transport equation (QHT) is applied to the study of thermal properties of Planck gas, i.e., a gas of massive particles with mass equal to the Planck massM _P = (łc/G)^1/2 and whose relaxation time equals the Planck timeτ _p = (łG/c ⁵)^1/2. The quantum of thermal energy for a Planck gas,E ^Planck = 10¹⁹GeV, and the quantum thermal diffusion coefficientD ^Planck = (ħG/c)^1/2 are calculated. Within the framework of QHT the thermal phenomena in a Planck gas can be divided into two classes: for a time period shorter thanτ _p , the time reversal symmetry holds and for a time period longer thanτ _p , time symmetry is broken, i.e., a time arrow is created.     

基于时间透镜原理实现微波信号时间反演

时间反演电磁学是一门新兴学科. 高效的电磁时间反演信号获取方式是时间反演技术获得应用的关键. 本文研究了一种基于时域成像原理获得时间反演微波信号的方法. 首先根据时间透镜原理, 推导出了实现波形时间反演的条件, 并对波形反演的过程进行了数值仿真. 然后设计了两种满足反演条件的啁啾电磁带隙结构来构造色散信道, 并通过实验得到了一个时隙长度为1.5 ns的时间反演信号. 由于啁啾电磁带隙结构与理想色散信道的差异, 实验结果中存在波形失真. 文章最后对造成失真的原因进行了分析.     

The asymmetry of the tunneling time in type II semiconductor heterostructures

The tunneling time asymmetry in type II semiconductor heterostructures is related to the phase difference of the reflection coefficients for the two tunneling directions. Analytical expressions and numerical simulations are given for the difference between the left-to-right and right-to-left tunneling times in asymmetric, single and multiple barrier type II heterostructures.     

The laser calibration system of the ALICE time projection chamber

A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range |η| < 0.9. It is designed for a maximum multiplicity dN/dy = 8000. The aim of the laser system is to simulate ionizing tracks at predifined positions throughout the drift volume in order to monitor the TPC response to a known source. In particular, the alignment of the read-out chambers will be performed, and variations of the drift velocity due to drift field imperfections can be measured and used as calibration data in the physics data analysis. In this paper we present the design of the pulsed UV laser and optical system, together with the control and monitoring systems. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

光敏电阻响应时间的研究实验

用半定量方法研究了光敏电阻的响应时间与照射光的照度和波长的关系,并给出了光敏电阻的上升时间和下降时间的测量方法.该实验可作为本科生的探索性实验,有助于培养学生的综合和研究能力.     

噪声相互关联时间对Logistic系统亚稳态稳定性的影响

研究了噪声交叉关联时间对Logistic 系统亚稳态稳定性的影响.利用最陡下降法导出了系统亚稳态到稳态的平均第一通过时间的表达式. 数值计算结果表明:内噪声、外噪声、 内外噪声的相互关联时间削弱了亚稳态的稳定性,而内外噪声的关联增加了亚稳态的稳定性.