可溶性固体微粒密度的测量

可溶性固体微粒密度的测量青一平（湖南师范大学物理系长沙４１００８１）引言目前在大学物理实验中多采用比重瓶法、静力称衡法测量固体密度，但其实用范围局限于不溶性固体．为此，我们设计了一套仪器能对可溶性固体微粒的密度进行测量（包括吸水物质，如大米等），该实...     

测量细丝直径的一种新方法

利用力敏传感器的电压输出特性与受力之间的关系结合静力称衡法,从理论上推导出了测量细丝直径的公式,然后设计出了相应的实验方案并进行了验证.利用该公式测量出的细丝直径与常规方法测量出的细丝直径相比较,二者的测量结果相差甚小,说明测量细丝直径的方案确实可行.这种测量细丝直径的新方法,在实际生活和教学科研方面有一定的参考和应用价值.     

让实验给出问题的答案

让实验给出问题的答案智艾娣（洛阳师范高等专科学校４７１０２２）根据阿基米德原理用流体静力称衡法测固体密度时，待测固体的密度式中Ｍ为固体在空气中的质量，Ｍ；为固体完全浸没在已知密度为Ｐ。的液体中的质量．不少教科书对此实验都提出了“当水中的固体或瓶内附有...     

误差传递公式使用时应注意的一个问题

用流体静力称衡法测一固体的密度ρ使用公式ρ=ρ_t(m_1/(m_1-m_2)) (1)式中:ρ_t为水在测量时的密度,其误差可略去不计;m_1为物体在空气中的质量;m_2为物体在水中的视质量。在杨述武等编的《普通物理实验》(一、力学、热学部分)28页习题3中给出了     

一种测定铜的电化当量的方法

现行高中物理课本第二册(甲种本)中叙述的《测定铜的电化当量实验》方法比较繁杂,称量负极板上沉积的铜质量时要把极板从溶液中取出,经冲洗、烘干后再用天平称量。这样,既浪费时间又容易因冲洗使铜微粒脱落造成较大的实验误差。我用本文图示的装置,采取流体静力称衡法不用取出负极板面直接在溶液中称量.由于简化了手续,一般用5～10分钟就可完成测量,而且效果很好。     

测定一个油滴密度的方法

我们手边只有少量油时,怎样测定其密度?用称衡法或比重计来测,因难测其体积和数量太少而无法进行。如果该油与酒精和水不相溶,且密度在水和酒精密度之间时,则可用如下方法。在烧杯中放入半杯酒精,滴入油滴,油滴将沉在杯底。再用滴定管向酒精中滴入水,边滴边慢慢搅动,当看到油滴呈球状悬浮于液体中时即可停     

多种方法测定密度小于水的固体材料密度

阐述数种测定 ρ<1固体密度的方法 ,按照一定格式 ,从基本思想到分析讨论各方面顺序进行讨论     

固体和液体密度测定实验的改进

介绍测量固体和液体密度的一种新的实验方法     

用力敏传感器测量物体的密度

利用力敏传感器测量物体的密度,改进了传统的实验方法和仪器,实现了非电量电测,提高了实验的准确度和稳定性.     

粉末状固体密度的测定

比重瓶法是测定颗料状固体密度的一种方法[1-2]，但是测定颗粒极为细小的物质即粉末状固体物质密度时，用比重瓶法则存在一些问题．我们根据多次实验测定的经验，对比重瓶法做了些改进，改进后的方法对减小实验误差，降低操作难度方面效果明显．一、比重瓶法测定颗粒状固体物质的密度通常测定步骤如下：1．将比重瓶装满水后，塞上中心有细孔的塞于，擦去溢出的水，称量质量为M1．2．称量粒状物体的质量为M。3．将粒状物体倒入装有水的比重瓶，重新按步骤1操作，称量混合质量为M3．4．计算出粒状物体的密度式中PO为测试温度下水的密度．二…     

Entrainment of a spatially extended nonlinear structure under selective forcing

The response of a nonlinear state to a variable forcing periodic in space is studied in an extended dynamical system consisting of a liquid crystal layer driven to convection. Both the statics and the dynamics of the entrainment and the locking effects are analyzed. The dynamics of the evolution are controlled by topological singularities that allow a diffusion of the phase. The mechanisms involved are related to the role of the defects in systems undergoing spontaneous symmetry breakings.     

非惯性系静力学的分析力学方法

非惯性系中的相对平衡问题,除矢量力学方法外,还可用非惯性系分析静力学方法处理。     

四翼梁式次镜支撑结构的研究

为了优化大型望远镜次镜支撑结构的静力学和动力学性能,采用有限元分析的方法,计算了次镜支座最大变形与次镜支座的偏置角、四翼梁叶片厚度的关系;分析了四翼梁结构的频率与叶片偏置角的关系.分析证明当次镜支座偏置一定角度时能改善结构的静力学性能;当相对的两片叶片从直径线上错开一定的距离,对提高望远镜的谐振频率是十分有利的,在两者之间综合取舍确定了四翼梁的优化形式.分析结果表明,优化后的四翼梁结构的静力学和动力学性能均有提高.     

Volume change,lattice strain and non-linear screening in dilute heterovalent alloys: study of A1Li

The electron - liquid pseudopotential theory is used together with the lattice statics method to calculate the lattice distortion around a solute atom in a simple metal host. It is found that for a heterovalent solute not only the third, but also the fourth order non-linear screening contributions to the displacing forces have to be retained in determining the long range displacement field. Our diffuse elastic neutron scattering data for $\text{Al}$Li single crystals show a particular structure near the (110) point in wave-number space, and also confirm the slight contraction of the average lattice spacing on dissolving Li atoms. By using local ion-electron model potentials, calculated for pure Al and Li metals, the origine of this peculiar contraction could be clarified and the structure in the cross section curve is reproduced.     

Physico-mathematical simulation of methane and argon removal absorption process by liquid ammonia from synthesis gas of ammonia production

Abstract

The elaboration of the theoretical experimental model of the absorption process under a pressure of 30 MPa and moderate temperatures included the experimental research of methan and argon absorption from the five-component mixture H₂-N₂-CH₄-Ar-NH₃ by liquid ammonia on a pilot plant and carrying out the computerized research of process statics.     

激光直射式CCD体重计的设计研究

基于拉伸法测量金属丝的杨氏模量这一实验,把改进后的激光光杠杆,应用到人体称重上．根据位移量与所加重物质量成线性关系,通过数据采集和编程,将体重通过液晶显示出来,设计制作成激光直射式CCD体重计．测量结果显示,精确度可以到0．01kg,拓展了杨氏模量的应用方向,启发同学们的发散思维,将物理实验与生活实践紧密相连．     

Anharmonic lattice statics analysis of 180 ° and 90° ferroelectric domain walls in PbTiO3

This paper presents an anharmonic lattice statics analysis of 180?°?and 90?°?domain walls in tetragonal ferroelectric perovskites. We present all the calculations and numerical examples for the technologically important ferroelectric material PbTiO₃. We use shell potentials that are fitted to quantum mechanics calculations. Our formulation places no restrictions on the range of the interactions. This formulation of lattice statics is inhomogeneous and accounts for the variation of the force constants near defects. The discrete governing equations for perfect domain walls are reduced using symmetry conditions. We solve the linearized discrete governing equations directly using a novel method in the setting of the theory of difference equations. We calculate the fully nonlinear solutions using modified Newton–Raphson iterations.     

Point defect interaction in alkali halide crystals

Abstract

Molecular statics method is used to determine the energy and configuration peculiarities of vacancy-bivacancy interaction in alkali halide crystals. It is shown that high level of local vacancy supersaturation defines the possibility of cluster formation. The study of carrier traps by luminescence methods is used to reveal vacancy clusters.     

并联传感器系统压力传感器故障诊断系统设计

在工业生产过程中电子皮带秤普遍采用多个称重传感器输出信号的并联方法,而该方法对多个称重传感器无法独立采集同时无法准确判断故障。应用TI公司MSC1210单片机最小系统和信号分离器,设计一种并联传感器系统压力传感器故障诊断系统,实现多个称重传感器并联应用时的独立采集;发明一种皮带秤称重传感器累计量校准方法,将不断变化的累计量转换成定量值实现并联传感器系统压力传感器故障诊断。结果表明该系统较好实现多个称重传感器的独立采集和故障传感器判断,为皮带秤等计量装置并联传感器系统的技术升级提供有效手段。     

Two-dimensional,blue phase tactoids

ABSTRACT

We use full nematohydrodynamic simulations to study the statics and dynamics of monolayers of cholesteric liquid crystals. Using chirality and temperature as control parameters, we show that we can recover the two-dimensional blue phases recently observed in chiral nematics, where hexagonal lattices of half-skyrmion topological excitations are interleaved by lattices of trefoil topological defects. Furthermore, we characterise the transient dynamics during the quench from isotropic to blue phase. We then proceed by confining cholesteric stripes and blue phases within finite-sized tactoids and show that it is possible to access a wealth of reconfigurable droplet shapes including disk-like, elongated and star-shaped morphologies. Our results demonstrate a potential for constructing controllable, stable structures of liquid crystals by constraining 2D blue phases and varying the chirality, surface tension and elastic constants.