Direct experimental determination of the dispersion of a final state energy band

We report the first absolute and continous experimental determination of the dispersion of an unoccupied electron energy band in copper. This has been achieved by monitoring the extremal behaviour of binding energies in angular resolved photoelectron energy distribution curves obtained with a tunable light source. By this method the absolute value of the wave vector for transitions originating from the symmetry line ∑ was determined. The experiments confirm that the final state band deviates strongly from a parabola.     

采用单读码器件的串行编码绝对式光学编码器

传统绝对式光学编码器具有多个读码器件和多条沿码盘径向分布的编码码道,结构比较复杂,限制了绝对式编码器的应用范围和进一步的发展。提出了一种采用单读码器件的串行编码绝对式光学编码器,介绍了其工作原理和基本结构。该编码器采用单个读码器件逐个的按顺序读取位置编码,在不同阅读位置上读到的二值化信息在移位存储器中所构成的编码值具有唯一性,极大限度地简化了绝对式光学编码器的结构,为其小型化开辟了一条新的途径。     

Vacuum UV photoelectron intensity of gaseous compounds: I. HeI spectra of simple compounds

A new method for determining absolute photoionization cross sections for gaseous compounds is proposed. In this method a mixture of a sample and a standard gas (N₂) is used in photoelectron intensity measurements so that the relative intensity of the component is obtained with respect to N₂ The relative photoelectron band area is converted to the absolute photoionization cross section on the basis of the absolute cross-section data of N₂ recently reported by Samson et al. This method has been applied to various aliphatic compounds to study the effect of alkyl substitution on photoionization cross sections of O- and N-nonbonding electrons for 584-Å radiation.     

Determining the retardation of a wave plate by using spectroscopic method

A method for determining the retardation of a wave plate is presented. The method is based on polychromatic polarization interference technique. Through accurate judgment of the intersection points' wavelengths of the two orthogonal polarization transmittance spectrum curves, the apparent retardation, the absolute retardation values and the physical thickness of a wave plate can be measured at a wide spectral range from 400 nm to 800 nm. Experimental results show that the proposed method has very high precision. In addition, the method has a significant advantage that has high misalignment tolerance. The method reported here should have applications in fabrication and measurement of a wave plate.     

Transferability of dipole moment derivatives: A general method for the calculation of absolute rotational contributions

A general method for the calculation of absolute rotational corrections for the dipole moment derivatives is given based on the definition of pure geometrical distortions. The method is generally valid and allows the rotational contributions to be calculated for all modes of any molecule. The relation between absolute and relative corrections is discussed and the method is demonstrated by calculating the rotational corrections for a few asymmetrical molecules.     

绝对式光学编码器串行编码方法的研究

针对传统绝对式光学编码器各编码码道沿径向分布、结构复杂的缺点,提出了一种绝对式光学编码器的串行编码方法。在码盘上仅刻划一圈存储多位二值信息的编码码道,沿码盘圆周方向按一定位置布置的光敏元件并行读取的二进制数具有唯一性,对此二进制数查表译码,就可以实现绝对位置测量。与传统绝对式光学编码器相比,码盘直径小、光学图案简单,有利于绝对式编码器实现小型化和提高精度。     

Measurement of ultrasonic absorption in a gel by light diffraction and resonator methods

A new sample cell construction for a light diffraction method permits absolute measurements of the ultrasonic absorption coefficient for a strongly absorbing transparent gel. By means of this cell the absorption coefficient at 6.2 MHz has been measured as a function of the temperature in the gelling temperature range for a 25% (w/w) aqueous solution of the ABA polyoxyethylene-polyoxypropylene block copolymer PLURONIC^R F 127. The resonator method has been used under the same experimental conditions. The strongly absorbing gel causes overlapping of the resonance signals. A calibration based on resonance experiments compared with the absolute measurements yields a solution to that problem and thus makes the resonator method applicable to a strongly absorbing gel.     

Hyperfine field and correlation time measurements of Sm ions recoiling into gas and vacuum by the longitudinal decoupling method

The longitudinal decoupling method has been employed for absolute hyperfine field and correlation time measurements in heavy ions recoiling into gas and vacuum.Supported in part by the Israel Commission for Basic Research.     

Absolute Quantifications of Oxy- and Deoxyhemoglobin Concentrations by Combination of Differentially Resolved Spectroscopy and Spatially Resolved Spectroscopy

This letter proposes a theoretical framework to calculate absolute concentrations of oxy- and deoxyhemoglobin using continuous-wave near-infrared spectroscopy. While previous methods on this topic require assumptions on constant blood volume, the proposed method does not. Equations for the absolute concentrations were derived from a combination of the modified Beer–Lambert equation and the theory of diffusion of photons in turbid media. The method has an advantage over and is theoretically consistent with previous methods. It needs yet to be evaluated in an experimental study.     

New measurement of the ϒ-meson mass

The method of resonance depolarization has been used for the absolute energy calibration of storage ring VEPP-4. The beam polarization was measured by the up-down asymmetry of the synchrotron radiation back-scattered on the colliding beam. By scanning the ? resonance with the MD-1 detector, we obtained a massM=9460.59 ±0.12 MeV.     

一种双光梳多外差大尺寸高精度绝对测距新方法的理论分析

本文提出了一种双光梳多外差大尺寸高精度绝对测距的新方法, 结合基于双光梳互相关的多外差距离测量和基于重复频率的梳间拍频距离测量, 在不需要依靠脉冲飞行时间先验判断以及扫描重复频率或扫描参考光路的前提下实现km量程高精度绝对测距. 文章在光梳基本原理和测距方案的基础上, 建立了基于双光梳的大尺寸距离测量链理论模型, 讨论了多外差最低谱线和光梳重复频率稳定度对测量结果的影响, 并进行了大量仿真计算; 仿真结果表明, 在理想相位解调精度的前提下, 该方法的测距误差优于± 50 pm, 且多外差最低谱线的频率偏差对测距造成的影响远低于多外差测量的测距分辨力, 验证了该方法能够用于开展大尺寸高精度绝对测距研究. 关键词： 激光测距 飞秒光梳 重复频率 多外差干涉     

D-u关系的最小绝对值线性拟合法

 采用最小绝对值方法对几类物质的冲击波速度D与波后粒子速度u的关系进行了直线拟合,并将其与常用的最小二乘法拟合的结果进行了比较。结果显示：对于实验数据分散性较小的密实材料（金属、离子晶体、氧化物等）,两种方法拟合的线性系数一致;而对于实验数据分散性较大的一些疏松材料（包括液体等）,两种方法拟合的线性系数有差异。对所有物质,最小绝对值法拟合的平均绝对误差比最小二乘法拟合的要小,因而最小绝对值法较最小二乘法有更高的准确性。同时讨论了导致这两种拟合差异的因素。     

Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

A Fourier analysis method is used to accurately determine not only the absolute phase but also the temporal-pulse phase of an isolated few-cycle (chirped) laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It paves the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.     

表面辐射测温方法的设计原理

讨论了表面辐射测温方法的设计中所包含的几个基本问题:辐射的光谱和方向复杂性问题、光学设计问题以及电路设计问题,给出了具有普适意义的辐射测温基本分析式。比较了绝对辐射测温方法和相对辐射测温方法,指出前者须做标定,并且不宜进行温度场测量;后者无须标定,适合于温度场测量。     

Quantum: Einstein,Bohr and the Great Debate About the Nature of Reality,by Manjit Kumar

The history of absolute measurements of gravity is mentioned and the reasons for making absolute measurements are indicated. The principles and main advantages and difficulties of the main method—reversible pendulum, free fall, symmetrical free motion—are discussed and examples of each method are described. Problems of comparison of different determinations and of estimating systematic errors are considered.     

Absolute negative conductivity in graphene with the Hubbard interaction in a magnetic field

The current-voltage and current-magnetic field characteristics for a graphene with the electron Hubbard interaction at low temperatures have been calculated in terms of the average electron method. The characteristics obtained have been analyzed as a function of the frequency of the external ac electric field and the magnetic field strength. The portion with an absolute negative conductivity has been revealed.     

Absolute measurement of flats with the method of shift-rotation

We present an absolute measurement of flats in a Fizeau interferometer with the method of shift-rotation, which only requires rotational measurements and shift measurement with a translation. Experiments have been carried out to verify the validity of the absolute testing method, and the results show that the reference surface deviation measured with the shift-rotation method agrees well with that of another calibration result with traditional three-flat absolute procedure; the root-mean-square (RMS) of the residual figure between them is ～0.4 nm.     

Absolute coverage measurements: CO and oxygen on the (110) plane of tungsten

An effusion source, calibrated with a vibrating quartz microbalance, has been used to determine absolute coverages of CO and of oxygen adsorbed on a tungsten (110) plane by an extension of the field emitter detector method: The amount of gas reflected from the substrate is measured as a function of the absolute amount impinged per unit area; maximum coverage in the chemisorbed layer can be obtained very directly from this information. Work function increments vs. absolute coverages were measured in the same apparatus by the vibrating condenser method. Results were as follows: For virgin CO, adsorbed at 100 K, the maximum coverage obtained was CO/W = 0.71 ; this leads to a maximum coverage for beta or beta-precursor CO of CO/W = 0.28. The maximum work function increment for virgin CO was 0.8 eV. For oxygen, adsorption at 100 or 300 K a decrease in sticking coefficient by several orders of magnitude occurs when the coverage is O/W = 0.5. Adsorption at 20 K leads to the molecular precursor noted by Leung and Gomer, which converts to atomic oxygen at <50 K. By adsorbing at 20 K the O atom coverage can be increased to O/W = 0.62. Work function versus coverage data for this system are also presented.     

Correcting the systematic error of the density functional theory calculation: the alternate combination approach of genetic algorithm and neural network

The alternate combinational approach of genetic algorithm and neural network (AGANN) has been presented to correct the systematic error of the density functional theory (DFT) calculation.It treats the DFT as a black box and models the error through external statistical information.As a demonstration,the AGANN method has been applied in the correction of the lattice energies from the DFT calculation for 72 metal halides and hydrides.Through the AGANN correction,the mean absolute value of the relative errors of the calculated lattice energies to the experimental values decreases from 4.93% to 1.20% in the testing set.For comparison,the neural network approach reduces the mean value to 2.56%.And for the common combinational approach of genetic algorithm and neural network,the value drops to 2.15%.The multiple linear regression method almost has no correction effect here.     

准绝对式光学编码器的编译码原理

介绍了准绝对式光学编码器的测量原理,根据其码盘特点,设计了实用的编码算法.利用计算机编程辅助实现了最高17位的索引码道编码设计,并提出一种译码的方法,可以实现从循环二进制码到自然二进制码的快速转换,为其进一步工程实现提供理论基础.