基于贝叶斯优化的高能质子空间传输精确控制

综合考虑地磁场、高能质子的相对论效应以及同步辐射的影响,建立了质子在空间传输的单粒子运动模型。基于该模型,提出利用贝叶斯优化方法,实现给定质子能量下,质子从空间初始点传输到目标点的精确控制方法,获得了出射方向随出射位置的变化规律,当位置径向角取0°和180°时,位置轴向角的取值不会改变粒子的最优出射方向。研究结果为质子束在空间环境中的长程传输提供理论支撑。     

E2》H2的均匀正交电磁场中带电粒子的相对论运动

通过求解带电粒子在均匀电场中与坐标系选取无关的三维矢量相对论运动方程,进而利用洛伦兹变换方法,求得了带电粒子在E2>H2的均匀正交电磁场中相对论运动轨迹的一般三维矢量式.并使用Mathematica软件在直角坐标系中描绘了相应的粒子相对论运动轨迹图.     

不依赖守恒定律推导相对论质速关系

相对性原理要求粒子的动量和能量对于速度的依赖关系在不同的惯性系中具有相同的函数形式,由此无需利用守恒定律和洛伦兹变换公式直接推导出相对论质速关系,证明了守恒定律和洛伦兹变换公式都不是推导相对论质速关系的必要条件.由相对论质速关系进一步可得到惯性系的广义洛伦兹变换公式,从而揭示了质能关系和质速关系是比洛伦兹变换公式适用范围更广的相对论基本公式.     

动量中心系与核反应

本文利用动量中心系来讨论核反应问题，由四维动量的变换关系导出了相对论性的资用能和阈能的表达式，并提出了相对论形式的柯尼希定理。     

为相对论质量辩护

本文认为向初学者讲授狭义相对论时引入“相对论质量”的概念是必要的、方便的、如Ｅ＝ｍｃ＾２即体现了质量和能量间简单而优美的当量关系，本文指出反对相对论质量者实际上在讨论粒子系或光子系的问题时才避开相对论质量，特别指出相对论质量与力和速度间的夹角无关，反对相对论质量者由于错误地应用了牛顿第二定律才导出这种根本不在依赖关系。     

近独立粒子系压强的一个关系式

由非相对论、近独立粒子组成的系统，其压强有一个简单而重要的关系Ｐ＝３／２ｎε．＾－本文了其一般证法及一些应用。     

Coulomb—Volkov近似下电子在激光场中对核的相对论散射

本在Coulomb-Volkov近似下，研究了激光场中电子对核的相对论散射。电子出射与入射态分别用Volkov波函数和Coulomb-Volkov波函数来描述。数值计算给出了辐射场修正的散射截面及其对激光强度和频率的依赖关系，并与相应的Born近似结果进行了比较。     

从陈子定理看相对论力学

通过巧妙地让陈子定理包含光速，可以得到粒子运动的相对论速度基本关系．根据这个相对论速度基本关系，可以推导出相对论质点动力学方程，能量质量关系，动量能量关系，洛伦兹变换等结果．     

伪自旋对称情形下Rosen-Morse类型势场中相对论粒子的束缚态

在伪自旋对称情形下研究了Rosen-Morse类型势场中相对论粒子的束缚态,利用Nikiforov-Uvarov方法求解了伪自旋对称情形下的Klein-Gordon和Dirac方程,得到了相对论粒子被束缚在Rosen-Morse类型势场的精确束缚态解.     

轻粒子发射时间随测量角的变化

利用小相对角关联方法测量了25MeV/u⁴⁰Ar+⁹³Nb反应中关联出射的轻粒子.通过与三体弹道模型的比较,从关联函数提取了轻粒子的发射时间.结果表明,轻粒子的发射时间随粒子能量的升高而降低,从低能的约600fm/c下降至高能的约50fm/c.将此数据与⁴⁰Ar+¹⁹⁷Au反应中的发射时间进行了比较,发现随着实验室系角度的增加,提取的轻粒子的发射时间变长,并认为其原因在于随发射角度的增加,前平衡发射成份越来越少,平衡发射成份增加.     

The geometry of Larmor nutation

The nutation accompanying the well-known Larmor precession discussed with respect to an inertial frame in an earlier paper is now considered in the rotating Larmor frame where the precession is absent and the nutation is therefore fully emphasized. It is shown that, in this frame, the nutating vector generates, in general, what may be called interpenetrating partial cones, the two parts of which merge into a single cone traced twice over, when the orbit of the charged particle changes to a circle — giving an immediate explanation of the discontinuous jump in the nutation frequency to twice its value as the orbit changes continuously from an ellipse to a circle.     

Frame dragging in the field of Kerr family

The interesting phenomenon of frame dragging which is associated with the rotation of the source in the field of Kerr family is discussed, and the angular velocity of an uncharged test particle is obtained with a straightforward mathematical method.     

单帧单曝光图像法测量气固两相流速度场

本文提出一种基于单帧单曝光图像的气固两相流固相颗粒的速度场测量方法。通过控制相机的单次曝光时间获得流场中颗粒的单帧运动模糊图像,运用分水岭算法分割图像,提取颗粒,由自相关函数获得各颗粒的速度大小和方向,重建二维速度场。利用该方法对玻璃珠在空气中重力沉降的速度测量结果与理论值基本一致,矢量场与颗粒运动轨迹相符,说明该方法可以用于气固两相流速度场的测量。研究发现使用片光源比背光源能够获得更加准确的速度值。     

Slip effects on streamline topologies and their bifurcations for peristaltic flows of a viscous fluid

We discuss the effects of the surface slip on streamline patterns and their bifurcations for the peristaltic transport of a Newtonian fluid. The flow is in a two-dimensional symmetric channel or an axisymmetric tube. An exact expression for the stream function is obtained in the wave frame under the assumptions of long wavelength and low Reynolds number for both cases. For the discussion of the particle path in the wave frame, a system of nonlinear autonomous differential equations is established and the methods of dynamical systems are used to discuss the local bifurcations and their topological changes. Moreover, all types of bifurcations and their topological changes are discussed graphically. Finally, the global bifurcation diagram is used to summarize the bifurcations.     

Protonic decay of oriented nuclei

On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid.     

Tomographic Description of a Quantum Wave Packet in an Accelerated Frame

The tomography of a single quantum particle (i.e., a quantum wave packet) in an accelerated frame is studied. We write the Schrödinger equation in a moving reference frame in which acceleration is uniform in space and an arbitrary function of time. Then, we reduce such a problem to the study of spatiotemporal evolution of the wave packet in an inertial frame in the presence of a homogeneous force field but with an arbitrary time dependence. We demonstrate the existence of a Gaussian wave packet solution, for which the position and momentum uncertainties are unaffected by the uniform force field. This implies that, similar to in the case of a force-free motion, the uncertainty product is unaffected by acceleration. In addition, according to the Ehrenfest theorem, the wave packet centroid moves according to classic Newton’s law of a particle experiencing the effects of uniform acceleration. Furthermore, as in free motion, the wave packet exhibits a diffraction spread in the configuration space but not in momentum space. Then, using Radon transform, we determine the quantum tomogram of the Gaussian state evolution in the accelerated frame. Finally, we characterize the wave packet evolution in the accelerated frame in terms of optical and simplectic tomogram evolution in the related tomographic space.     

探索惯性系

针对牛顿力学框架的两大疑难,结合朗格惯性系的定义,从理论上分析了星球参考系与质心参考系,并指出了在什么条件下它们可以充当惯性系.     

Charged particle orbits in Kerr geometry with electromagnetic fields as viewed from locally non-rotating frames

The charged particle orbits in electromagnetic fields on Kerr background as viewed from a locally non-rotating frame do not exhibit non-gyrating bound orbits, which was an essential feature in the earlier study of Prasanna and Vishveshwara, thus showing the non gyration to be due to the effect of dragging of inertial frames produced by the rotating black hole.     

The continuous wave electron paramagnetic resonance experiment revisited

When the modulation frequency used in continuous wave electron paramagnetic resonance (cw EPR) spectroscopy exceeds the linewidth, modulation sidebands appear in the spectrum. It is shown theoretically and experimentally that these sidebands are actually multiple photon transitions, sigma(+)+kxpi, where one microwave (mw) sigma(+) photon is absorbed from the mw radiation field and an arbitrary number k of radio frequency (rf) pi photons are absorbed from or emitted to the modulation rf field. Furthermore, it is demonstrated that both the derivative shape of the lines in standard cw EPR spectra and the distortions due to overmodulation are caused by the unresolved sideband pattern of these lines. The single-photon transition does not even give a contribution to the first-harmonic cw EPR signal. Multiple photon transitions are described semiclassically in a toggling frame and their existence is proven using second quantization. With the toggling frame approach and perturbation theory an effective Hamiltonian for an arbitrary sideband transition is derived. Based on the effective Hamiltonians an expression for the steady-state density operator in the singly rotating frame is derived, completely describing all sidebands in all modulation frequency harmonics of the cw EPR signal. The relative intensities of the sidebands are found to depend in a very sensitive way on the actual rf amplitude and the saturation of single sidebands is shown to depend strongly on the effective field amplitude of the multiple photon transitions. By comparison with the analogous solutions for frequency-modulation EPR it is shown that the field-modulation and the frequency-modulation technique are not equivalent. The experimental data fully verify the theoretical predictions with respect to intensities and lineshapes.     

也谈关于参照系的选取——对“椭圆摆的一种实现方法”一文的商榷

本文旨在指出相关文献中关于质点轨迹结果中的错误,并利用不同于相关文献的惯性参照系,给出修正和改进后的结果．