物理天平的分度值与读数分格

天平的分度值(感量)与负荷状态有关,不同类型物理天平铭牌上的分度值有的与游码读数分格一致,有的不一致,它们与哪个负荷量相应呢?下面是我们对两种天平进行的实测结果;天平Ⅰ的铭牌分度值与零负荷状态相应;天平Ⅱ的铭牌分度值与最大负荷状态相应。另外,刀口磨损情况对感量也有很大影响。因此要正确读取数据,必须测量给定负荷态的感量。可见,随着负荷增加,分度值增大,灵敏度降低。     

光学传递函数测量仪刀口和狭缝两种扫描方法比较分析

GC 2 11光学传递函数分析仪是北京理工大学光电工程系自行研制的一台能对折轴、潜望等复杂光学系统进行测量的大型精密测量仪。其测量采用了刀口扫描和狭缝扫描两种方式。但实际应用时 ,用刀口扫描方式得到的光学传递函数值总是小于理论值。通过分析计算 ,得出在相同条件下 ,刀口扫描法比狭缝扫描法抗干扰能力差的结论 ,弄清了长期以来刀口扫描测试数值偏小的问题。     

光学纤维面板像质测量

本文讨论光学纤维面板像质评价,由刀口响应转换为调制传递函数,进而用MTF 指标评价面板像质的可能性。本文在实验的基础上,分析得出光学纤维面板在低频范围近似等晕。通过对面板实测刀口响应及其传递函数数据的分析,提出两种评价面板像质的方法。一是刀口响应曲线,二是低频传递函数加刀口响应的背景串光。前者灵敏度高,后者物理意义更为确切,两者均可在光学纤维面板刀口响应检测仪器上实施。     

天平使用方法的教学探讨

众所周知,物理测量是物理教学中一个必不可少的环节.在初中物理实验中,质量的测量尤其重要,它是测量物质密度实验的基础,因此,我们必须掌握用天平测量物体质量的方法.常用的天平有托盘天平和学生天平,下面就谈谈这两种天平使用中存在的一些问题以及解决这些问题的方法.     

选择合格天平,做好物理实验

在初中物理教学中，正确的选择、使用和维护天平是搞好有关天平教学的关键．在新教材中，天平的实验是以托盘天平为主，在选择托盘天平时大致从以下几个方面进行：一、检查天平指针能否指分度盘零刻度．一般天平横梁上的螺旋在没有调节到头以前，指针都能指分度盘的零刻度．但还是有一些天平，横梁上的螺旋已经调节到头了，指针仍然不能指分度盘的零刻度．出现这种现象时，需将天平托盘取下，拧开下面的螺丝，调节下面的配重沙粒，一直到天平指针指分度盘的零刻度为止．二、检查天平是否等臂．先将天平调节好，使指计指零刻度．再用两个相同…     

数字刀口仪定量检验非球面光学元件面形

构建了一台数字化刀口仪,利用该数字刀口仪对二次非球面光学元件进行实际检验,获得了非球面光学元件表面面形的均方根(RMS)值和峰谷(PV)值.将数字刀口仪测量结果与干涉仪测量结果进行比较,测量结果的一致性在0.001μm以内,验证了数字刀口仪定量检测非球面光学元件的可行性以及所研究的数字刀口仪的准确性.最后对测量结果进行...     

定量检验光学元件面形的数字刀口仪技术研究

在传统刀口仪的基础上,提出一种数字化刀口仪,利用该刀口仪可实现球面光学元件表面面形的定量检验。介绍数字刀口仪的组成、工作原理及测试过程等,并利用该刀口仪对一个半径为1000mm,口径为160mm的球面光学元件的面形进行了实际测量,给出了光学元件均方根值和峰谷值测量结果,最后对测量结果进行了讨论。     

使用内圆切割机切割光学玻璃

使用内圆切割机切割光学玻璃比用外圆开料机切割的老工艺有很多优点,下面介绍一下使用切割光学玻璃的一些体会: 一、老工艺及效果 1.用外圆开料机切割大玻璃片料,刀口宽25～3mm; 2.磨二个平行平面,加工余量为2.5mm; 3.开小方片,刀口宽2.5mm;     

电磁天平测量光速

电磁天平测量光速范淑华（武汉华中理工大学物理系４３００７４）本文提出的用电磁天平方法测量光速的实验，目的不是为了进一步提高测量精度而是为了帮助学生对电磁学的一些基本内容加深认识和理解．该实验的设计如图所示，电磁天平的一端为电容的一个极板，另一端为一个...     

基于刀口仪的空气成像演示实验

利用刀口仪和球面反射镜设计了空气成像演示仪.将热源置于球面反射镜和刀口仪点光源之间,改变空气的温度分布,使球面反射镜的反射光线发生偏折,在刀口后方即可以直观地观察到热空气流动的状态,即实现空气成像的演示实验.该演示实验装置简单,使用CCD采集图像,现象明显且易于观察,利于学生理解光学检测技术中刀口仪的原理.     

Application of the energy balance method to nonlinear vibrating equations

In this paper, He’s energy balance method is applied to nonlinear vibrations and oscillations. The method is applied to four nonlinear differential equations. It has indicated that by utilizing He’s energy balance method (HEBM), just one iteration leads us to high accuracy of solutions. It has illustrated that the energy balance methodology is very effective and convenient and does not require linearization or small perturbation. Contrary to the conventional methods, in energy balance method, only one iteration leads to high accuracy of the solutions. The results reveal that the energy balance method is very effective and simple. It is predicted that the energy balance method can be found wide application in engineering problems, as indicated in following examples.     

GaN ultraviolet Schottky barrier photodetectors with ZrO2 or SiO2 insulators

Organic light-emitting diodes (OLEDs) with high luminance efficiency were successfully fabricated using the LiF/N,N′-bis(1-naphyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) carrier balance structures. It was found that the insertion of the LiF/NPB carrier balance structures can balance the charge injection and transport, which is helpful in enhancing the performance of OLEDs. It was also found that we can achieve the best performance from the OLED with three pairs of LiF/NPB (0.3 nm/15 nm) structures. The luminance and transport efficiency were both enhanced with the increase in the numbers of pairs of LiF/NPB carrier balance structures. We can attribute the improvement to the better carrier balance at the device interface.     

激光光解自由基的TR-ESR研究

时间分辨电子自旋共振（TR-ESR）技术是探测和鉴定光化学反应过程中顺磁性中间体的强有力工具,利用TR-ESR技术观察到的化学诱导动态电子极化 (CIDEP) 可以为我们提供丰富的光化学反应机理、反应动力学等信息. 该文较为详细地介绍了CIDEP的4种机理和自行研制的一种零差拍平衡混频的时间分辨ESR波谱仪,总结了TR-ESR技术在光解自由基反应方面的应用.     

霍尔天平材料的多场调控

霍尔天平材料中层间耦合作用易于调控,基于此可以实现多组态磁存储模式,其区别于当前基于自旋阀或者磁性隧道结的传统二组态磁存储原理.与此同时,还可以在存储单元中实现信息的逻辑运算从而提高器件整体的运算效率.这一设计有利于自旋电子学器件的微型化、集成化,有望从物理原理上解决当前基于自旋阀或者磁性隧道结的传统二组态自旋电子学材料器件的技术瓶颈,进一步提高磁存储密度,为推动新型自旋电子学材料的研究开辟了一条新的研究思路.首先,本综述将介绍基于霍尔天平材料的磁存储器件的研究背景;其次,重点介绍霍尔天平存储逻辑器件一体化设计的提出与发展历程;再次,介绍霍尔天平材料关键指标-霍尔电阻比值的界面调控及物理机理探索;随后详细阐述霍尔天平体系中磁性斯格明子的产生与多场调控等动态行为.最后,简单介绍霍尔天平结构在其他相关材料中的扩展、应用,并展望其在未来器件应用中的前景.     

利用精密扭秤测量铜与磁场的相互作用

利用精密扭秤测量了抗磁性物质铜与外磁场的相互作用，其基本思想是充分利用精密扭秤对弱力的高灵敏度，从而可极大地降低传统方法中对外磁场强度的要求．初步的实验结果证实了这一方法的可行性．     

Remarks on the Energy Balance of Low Pressure Discharges

Including excitation and de-excitation processes, direct and stepwise processes of the ionization, the particle balance and the energy balance of a positive column are jointly studied. It is shown that even near the axis the energy flux due to the radial electron drift can be only neglected provided that the mean electron energy is considerably less than the ionization energy. In some cases, it appears easier to apply the total energy balance instead of the energy balance of the electron gas alone.     

The Effects of Comprehensive Exercise Program on the Adjustments of Standing Balance in Community-Dwelling Elderly Persons

The objective of this study was to assess the effect of comprehensive exercise program widely accepted as a community-based physical intervention for the prevention of falling in the elderly persons on their controlling standing balance. Twenty-six community-dwelling elderly persons (13 males and females; 69.8 ± 2.8 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise without exercise equipments. The intervention was continued for three months. Indicators of standing balance related to static balance, dynamic balance and postural response were measured before and after the intervention. As an effect of the intervention on static balance, the sway of center of pressure (COP) in the static stance significantly increased. In the dynamic balance, significant improvements were observed in one leg standing time, the 10-m gait time, functional reach. Additionally, the maximal movable length of COP which subjects can move voluntarily to right and left significantly increased. In the postural response, the integrated electromyography (IEMG) induced by postural response for sudden postural perturbation significantly decreased in the lower leg muscles. Since less muscular activities were sufficient to maintain posture, it was suggested that postural response was elicited more efficiently following the intervention. This study suggested that the comprehensive exercise program, which has been widely introduced as community-based interventions for the prevention of falling, have extensive effects on the control of standing balance covering static balance, dynamic balance and postural response in the elderly persons.     

基于电抗性质线判定三点式正弦波振荡器的相位平衡

在对三点式正弦波振荡器高频电路的应用中,当振荡器在满足振幅平衡条件的前提下,对判定它的相位平衡是否满足这一问题,提出了元件(包括组合元件)电抗性质线的概念,结果表明用电抗性质线能直观、准确地判定出三点式振荡器电路相位平衡满足与否.