关于正确评定测量结果的讨论

本文推出了平均值的包含因子与测量次数ｎ的正确关系，计算了两组实验结果的置信水准，纠正了文［１］的两个错误，得出了评定实验结果的一般结论。     

Hyperfine Interaction Constants of the HCCS and DCCS Radicals Studied by Fourier Transform Millimeter-Wave Spectroscopy

The rotational spectral lines of HCCS and DCCS have been observed with a Fourier transform millimeter-wave spectrometer in combination with a pulsed discharge nozzle. The HCCS radical is produced by discharging a mixture of C₂H₂ and CS₂ diluted in Ar. The DCCS radical is produced by using C₂D₂ instead of C₂H₂. The spectral lines of HCCS and DCCS in both the ²Π_3/2 and ²Π_1/2 states are measured in the frequency range from 16 to 48 GHz, and the molecular constants are determined accurately from a joint least-squares analysis with the reported millimeter- and submillimeter-wave data. The hyperfine interaction constants of the hydrogen and deuterium nuclei are determined for the first time, and are discussed in relation to the Renner-Teller effect on this molecule.     

近自由面水下爆炸气泡的运动规律研究

基于边界积分法建立水下爆炸气泡与自由面耦合数值模型;并开发相应的计算程序,计算值与实验值符合较好.从气泡与自由面相互作用的基本现象入手,运用开发的程序系统地研究了近自由面水下爆炸气泡的动态特性,包括近自由面气泡的环状回弹及自由面的水冢现象;研究距离参数、浮力参数以及强度参数等特征参数与自由面Bjerknes效应之间的关系,总结相关规律,近自由面气泡的动态特性与这些特征参数有密切的关系.并在研究过程中,讨论了基于Kelvin-impulse理论的Blake准则的适用范围,并解释了Blake准则的失效的原因. 关键词： 气泡 自由面 环状 水冢     

近自由面水下爆炸气泡的运动规律研究

基于边界积分法建立水下爆炸气泡与自由面耦合数值模型；并开发相应的计算程序，计算值与实验值符合较好.从气泡与自由面相互作用的基本现象入手，运用开发的程序系统地研究了近自由面水下爆炸气泡的动态特性，包括近自由面气泡的环状回弹及自由面的水冢现象；研究距离参数、浮力参数以及强度参数等特征参数与自由面Bjerknes效应之间的关系，总结相关规律，近自由面气泡的动态特性与这些特征参数有密切的关系.并在研究过程中，讨论了基于Kelvin-impulse理论的Blake准则的适用范围，并解释了Blake准则的失效的原因.     

Investigation of magnetic field effect on surface and finite-site free energy in one-dimensional Ising model of nanosystems

We investigate a one-dimensional (1-D) Ising model for finite-site systems. The finite-site free energy and the surface free energy are calculated via the transfer matrix method. We show that, at high magnetic fields, the surface free energy has an asymptotic limit. The absolute surface energy increases when the value of f (the ratio of magnetic field to nearest-neighbor interactions) increases, and for f?≥?10 approaches a constant value. For the values of f?≥?0.2, the finite-site free energy also increases, but slowly. The thermodynamic limit in which physical properties approach the bulk value is also explored.     

Effects of self-fields on dispersion relation and growth rate in two-stream electromagnetically pumped free electron laser with axial guide magnetic field

A theory for a two-stream free-electron laser （FEL） with an electromagnetic wiggler （EMW） and axial guide magnetic field is developed. In the analysis, the effects of self-fields are taken into account. The growth rate is derived. The characteristics of the growth rate are studied numerically. The dependence of the normalized wave number, which corresponds to the maximum growth rate, on the cyclotron frequency is presented. The comparisons between the normalized maximum growth rate and its corresponding wave number normalized by employing the axial magnetic field, for the cases with and without self-fields in the two-stream FEL are studied numerically.     

γ辐射引发淀粉目由基衰减的动力学研究

用ESR方法研究了红薯淀粉在y射线预辐照下,产生的淀粉自由基特性及其室温下的自由基衰减动力学反应。结果表明在室温条件下,淀粉自由基的相对浓度随辐射剂量的增大而增加。自由基相对浓度的室温衰减用二级反应动力学处理,求得了衰减速率常数和淀粉自由基反应的半衰期。     

Effects of self-fields on gain in two-stream free electron laser with helical wiggler and an axial guiding magnetic field

The theory for the two-stream free electron laser （FEL） consisting of a relativistic electron beam transporting along the axis of a helical wiggler in the presence of an axial guiding magnetic field is proposed and investigated. In the analysis, the effects of self-fields are taken into account. The electron trajectories and the small signal gain are derived. The characteristics of the linear-gain and the normalized maximum gain are studied numerically. The results show that there are seven stable groups of orbits in the presence of self-fields instead of two groups reported in the absence of the self-fields. It is also shown that the normalized gains of three groups decrease while the rest increase with the increasing of normalized cyclotron frequency g20. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 3. The results show that the normalized maximum gain is enhanced in comparison with that of the single stream.     

1.19米相互作用长度的喇曼自由电子激光器实验

利用新研制的1.3米双螺线波荡器以及与此相配合的引导场磁体,使自由电子激光相互作用长度从308mm可以最大增加到1190mm.总体实验证明,最大的激光辐射峰值功率达12MW电子转换效率是3.7%.     

用概率知识推导Tait平均自由程

通过一些简单的概率假设，给出了Tait平均自由程的新的推导，并讨论了对强度分布的影响。     

物理实验教学要注重学生非智力因素的培养

智力因素与非智力因素相互影响，只有注重学生非智力因素的培养才能提高教学质量。     

Effects of self-fields on electron trajectory and gain in two-stream electromagnetically pumped free-electron laser with ion channel guiding

A theory for the two-stream free-electron laser with an electromagnetic wiggler (EMW) and an ion channel guiding is developed.In the analysis,the effects of self-fields have been taken into account.The electron trajectories and the small signal gain are derived.The stability of the trajectories,the characteristics of the linear gain and the normalized maximum gain are studied numerically.The dependence of the normalized frequency ω corresponding to the maximum gain on the ion-channel frequency is presented.The results show that there are seven groups of orbits in the presence of the self-fields,which are similar to those reported in the absence of the self-fields.It is also shown that the normalized gains of 2 groups decrease while the rest increase with the increasing normalized ion-channel frequency.Furthermore,it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 4.     

The effects of self-fields on the electron trajectory and gain in a two-stream electromagnetically pumped free-electronlaser with axial guiding field

A theory of a two-stream free-electron laser in a combined electromagnetic wiggler (EMW) is developed, in which we use an axial-guide magnetic field and take into account the effects of the self-fields. The electron trajectories and the small signal gain are derived. The stability of the trajectories, the characteristics of the linear-gain, and the normalised maximum gain are studied numerically. The results show that there are nine stable groups of orbits in the presence of self-fields instead of seven groups reported in the absence of the self-field. It is also shown that the normalised gains of four groups of the orbits are decreasing and those for the rest of them are increasing with growing \barΩ₀. Furthermore, it is found that the two-stream laser with self-field enhances the maximum gain in comparison with the single stream case.     

Investigation of a supersonic free jet by means of a laser anemometer

The present paper reports on experimental investigations conducted by means of a laser anemometer in order to analyze a supersonic free jet escaping from a non-divergent nozzle into the free atmosphere. As the free jet is generated in a shock tube, thereby presenting a blow time of the order of 1 ms only, the laser anemometer also proved to be very suitable as a measuring probe to study transient phenomena involving high flow velocities. The experimental results achieved are compared to theoretical predictions.     

Electrostatic Fluid Accelerator under High‐Speed Free Air Stream

The electrostatic fluid accelerator (EFA) generates ionic wind with a simple structure that barely obstructs the free air stream or produce excessive noise. This paper presents the velocity characteristics of an EFA under a high speed free air stream to simulate an EFA‐powered propulsor. The results show that when the EFA generates identical velocity to the free air stream, the EFA contributes 25% of the resultant velocity. When the EFA is replaced by a rotary fan that generates identical velocity to the free air stream, the fan contributes only 13.4% of the resultant velocity. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

线极化静电摇摆器自由电子激光的理论分析

给出一种结构简单,具有自聚焦能力的短周期线极化静电摇摆器的场分析,并对相应的自由电子激光理论和自聚焦原理作了初步探讨。     

Studies on ultrasonic properties of different series of liquid systems

Fifteen specimens of tetraalkoxysilanes were prepared and their tentative tetrahedral structures proposed. Ultrasonic velocities were measured over the temperature range of 30–80°C using a multifrequency ultrasonic interferometer. Intermolecular free length, free volume and internal pressure of different classes of compounds were evaluated using the experimentally determined ultrasonic velocity, density, specific heat, thermal expansion, viscosity and molecular weight employing different empirical equations and the data obtained were compared.     

Topological evolution near the turbulent/non-turbulent interface in turbulent mixing layer

The topological evolution near the turbulent/non-turbulent interface (TNTI) in turbulent mixing layer is studied by means of statistical analysis of the invariants of velocity gradient tensor (VGT) based on direct numerical simulation data. The dynamics of topological evolution is investigated in terms of the source terms of the evolution equations for the invariants, including the pressure effect term, viscous effect term and interaction term among the invariants. It is found that the local topology of fluid particles at the TNTI evolves from non-focal region to focal region in the plane of the second (Q) and the third (R) invariants of the VGT. The topological evolution is mainly associated with the pressure effect term in the TNTI region. According to the analysis of the evolution of enstrophy and dissipation, the enstrophy increase and the dissipation decrease are revealed in the TNTI region, which are caused by viscous vorticity diffusion near the TNTI. A weak correlation between the strain rate and the rotation rate is found in the TNTI region which is related to the reduction of enstrophy production. The alignments between vorticity and strain near the TNTI are investigated and a strong alignment of the vorticity with the extensive eigenvector direction is identified in the TNTI region.     

Comment on: “Epidemic spreading on heterogeneous networks with identical infectivity” [Phys. Lett. A 364 (2007) 189]

In [R. Yang, et al., Phys. Lett. A 364 (2007) 189], it has been introduced a network-based Kermack-McKendrick-like SIR epidemic model, in which each node shows an identical capability of contact A and in which it has been claimed that, on scale free networks, the value A⁻¹ would be a threshold value for the density of recovered individuals. We show here that the recovered individuals cannot follow the claimed threshold behaviour. Furthermore, we give a biologically sound threshold ruling the transitory dynamics of the epidemics.     

Long-distance quantum teleportation assisted with free-space entanglement distribution

Faithful long-distance quantum teleportation necessitates prior entanglement distribution between two communicated locations. The particle carrying on the unknown quantum information is then combined with one particle of the entangled states for Bell-state measurements, which leads to a transfer of the original quantum information onto the other particle of the entangled states. However in most of the implemented teleportation experiments nowadays, the Bell-state measurements are performed even before successful distribution of entanglement. This leads to an instant collapse of the quantum state for the transmitted particle, which is actually a single-particle transmission thereafter. Thus the true distance for quantum teleportation is, in fact, only in a level of meters. In the present experiment we design a novel scheme which has overcome this limit by utilizing fiber as quantum memory. A complete quantum teleportation is achieved upon successful entanglement distribution over 967 meters in public free space. Active feed-forward control techniques are developed for real-time transfer of quantum information. The overall experimental fidelities for teleported states are better than 89.6%, which signify high-quality teleportation.