Differential cross sections of elastic electron scattering from CH4. CF4 and SF6 in the energy range l00-700eV

We investigate the differential cross sections （DCS） of elastic electron scattering from CH4, CF4 and SF6 at six impact energies in a range of 100 700eV by employing the independent atom model （IAM） together with the relativistic partial waves. The atom is present in an optical potential which is complex, spherically symmetric, and energy dependent. The optical potential of the atom is the sum of the direct static, dynamic polarization, local exchange and modified absorption potentials. The results obtained by using a modified absorption potential show significant improvements on the unmodified absorption potential results. The present results are generally in good agreement with experimental data available. In addition, the present results indicate that the structure of molecule manifests the observable effects on electron- molecule scattering.

Measurements of the Differential Elastic and Inelastic Scattering Cross Sections of ^(12)C

The differential elastic and inelastic scattering neutron cross sections of 12C atEn=14.7 MeV produced by the T（d,n）4He reaction were measured using an associatedparticle fast neutron TOF spectrometer at 15 angles ranging from 15° to 130°.Theflight path was 2.54 m.The neutron detector consisting of an ST-451 liquid scintillatorwas massively shielded.

Measurements of NO_2 mixing ratios with topographic target light scattering-differential optical absorption spectroscopy system and comparisons to point monitoring technique

A topographic target light scattering-differential optical absorption spectroscopy （＇IbTaL-DOA~） system is de- veloped for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases. The telescope of the ToTaL-DOAS system points to targets which are located at known dis- tances from the measurement device and illuminated by sunlight. Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets, A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011. The measurement data are compared with con- centrations measured by the point monitoring technique at the same site. The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path.

Double Differential Cross-Section for the Ionization of Hydrogenic 2S Metastable State

Double differential cross-sections of first Born estimation for ionization of hydrogenic 2S state by electrons are assessed for various kinematics situations in the asymmetric coplanar geometry. A final state wave function of multiple scattering theory is followed in this study. The present outcomes are compared with those of hydrogenic ground state, 2P state and ground state experimental results. Obtained findings show a good qualitative agreement with existing results.

Polarization and exchange effects in elastic scattering of electron with atoms and ions

Laser-induced electron diffraction（LIED）, in which elastic scattering of the returning electron with the parent ion takes place, has been used to extract atomic potential and image molecular structures with sub-？A precision and exposure time of a few femtoseconds. So far, the polarization and exchange effects have not been taken into account in the theoretical calculation of differential cross section（DCS） for the laser-induced rescattering processes. However, the validity of this theoretical treatment has never been verified. In this work, we investigate the polarization and exchange effects on electron impact elastic scattering with rare gas atoms and ions. It is found that, while the exchange effect generally plays a more important role than the polarization effect in the elastic scattering process, the exchange effect is less important on electron–ion collisions than on electron–atom collisions, especially for scattering in backward direction. In addition, our calculations show that, for electron–atom collisions at incident energies above 50 e V, both the polarization and exchange effects can be safely neglected, while for electron–ion collisions, both the polarization and exchange potentials do not make substantial contributions to the DCS at incident energies above 20 e V and scattering angles larger than 90？. Our investigation confirms the validity of the current LIED method.

Absolute differential, elastic integrated and mqment transfer cross sections for electron-OCS collisions at intermediate and high energies

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between atoms in a molecule, is firstly employed to calculate the absolute differential, elastic integrated and moment transfer cross sections for electron scattering by OCS over the incident energy range from 200 to 1000 eV using the additivity rule model at Hartree-Fock level. The calculated results are compared with those obtained by experiment and other theories wherever available, and good agreement is obtained over a wide energy range. It is shown that the additivity rule model together with the modified potential is completely suitable for calculating the absolute differential, elastic integrated and moment transfer cross sections of electron scattering by molecules such as OCS.

THE DONNACHIE-LANDSHOFF MODEL AND Σ^(-)p ELASTIC SCATTERING

Using theΣ-form factor it is shown that the Donnachie-Landshoff pomeron gives a good description of the high energy total and elastic differential cross-section data forΣ-p scattering.

Proton Elastic Scattering from ^14Be and Halo Effects

The elastic scattering of p-^14Be system at Elab = 200 MeV is evaluated within the relativistic impulse approximation. We discuss the effects of the halo neutrons on the three observables of the elastic scattering system, such as differential cross section dσ/ dΩ, analyzing power Ay and spin rotation Q. The results of the three observables of the elastic scattering of p-^14Be system are compared with those of p-^12C and p-^16O systems at the same energy as E1ab = 200 MeV. We have found that in the small angular region the Ay and Q, as well as dσ/dΩ, are quite sensitive to the nucleon density distributions on the surface of the target nucleus and offer some unique behaviors of halo nuclei.

K^- Nucleus Elastic Scattering and Momentum-Dependent Optical Potentials

The K? nucleus differential elastic scattering cross section for 12C and 40Ca at is calculated with three momentum-dependent optical potential models, which are density-dependent, relativistic mean field, and hybrid model, respectively. It is found that the forms of momentum-dependent optical potential models proposed by us are reasonable and gain success in the calculations and the momentum-dependent hybrid model is the best model for the K? nucleus elastic scattering.

The Effect of Anisotropic Intranuclear Scattering on Angular Distribution of Nucleons in Preequilibrium Reaction

A discussion on double differential cross section of nucleons based onanisotropic intranuclear scattering is presented since the anisotropic behavior ofnucleon-nucleon scattering becomes strong with increasing incident energy but in pre-vious theories the isotropic picture is used.The calculated results indicate that theanisotropic effect slightly improves the agreement with the experimental data.

Unconventional Medium Effect in K^+ Scattering From ~6Li,^(12)C,^(28)Si and ^(40)Ca

The results of comprehensive microscopic optical model calculations are pres-ented for the K+ scattering from 6Li,12C,28Si and 40Ca at incident momenta 400-800MeV/c.The unconventional medium effect （i.e.the density-dependent correction forthe K+-nucleon scattering amplitude） is considered in two approaches.Both results arein agreement with recent experimental data.The influence of the correction on K+ scat-tering from different nuclei are discussed in detail and only a weak dependence of thein-medium nucleon“swelling”effects on the mass number of target nuclei is found ex-cept for very light loosely-bound nucleus.

心房颤动伴室内差异性传导患者心电散点图形态特征研究

目的:研究心房颤动伴室内差异性传导(简称差传)患者心电散点图形态特征。方法:选取2019年9月—2022年9月温州市中西医结合医院收治的心房颤动患者204例为研究对象。所有研究对象行心电散点图检查,制作24h心电散点图,并依据心房颤动类型分为单纯性心房颤动组(n=49)、阵发性心房颤动组(n=41)、心房颤动伴逸搏心律组(n=32)、心房颤动伴室性期前收缩(简称室早)组(n=44)及心房颤动伴差传组(n=38)。观察各组心电散点的图形特点及各组间的图形差异,比较各组的最慢心率、最快心率及平均心率,测量各组的B线斜率。结果:单纯性心房颤动组为单一扇形,边缘与坐标轴存在一定的角度和距离;阵发性心房颤动组同时具有扇形与棒球形;心房颤动伴逸搏心律组为45°线远端细棒状、三分布图形、远端边缘存在被“曲尺”切成的平直状;心房颤动伴室早组为房室分离,心房颤动伴差传组为单一扇形,联律间期短而不固定。五组最慢心率比较,差异无统计学意义(P>0.05);心房颤动伴差传组最快心率及平均心率高于其他四组,差异有统计学意义(P<0.05);心房颤动伴室早组B线斜率低于其他四组,差异有统计学意义(P<0.05)。结论:不同类型的心房颤动具有不同的心电散点图形态特征,且心率及B线斜率存在差异,可为临床鉴别诊断提供参考。

A convolution algorithm to calculate differential cross sections of the Ring effect in the Earth's atmosphere based on rotational Raman scattering

The Ring effect refers to the filling in of Fraunhofer lines, which is mainly attributed to the rotational Raman scattering of solar spectra by N2 and O2 molecules in the atmosphere. The Ring effect is one of the most significant factors affecting the accuracy of retrieving concentrations of atmospheric trace gases, such as NO2 and SO2, from satellite observations through differential optical absorption spectroscopy. First in this study, the solar spectrum measured by the Ozone Monitoring Instrument onboard NASA Aura is convolved with the rotational Raman cross section of the atmosphere, which is calculated from the rotational Raman cross sections of N2 and O2 molecules, and divided by the original solar spectrum. The slowly varying term is removed by fitting it with a cubic polynomial to obtain the differential Ring spectrum. The results agree well with the calculations using a radiative transfer model (R2=0.9663). Second, the differential Ring spectrum is computed using two fixed wavelengths of 410 nm and 488 nm, and the resulting differential Ring spectra are similar to that calculated with varying wavelengths and agree well with the calculation using the radiative transfer model (R2=0.9624 and 0.9639 respectively). The computation time using the fixed wavelength is about 0.128% of that using a varying wavelength. Finally, we found that the frequency spectrum of the Raman cross sections for the atmosphere, N2 molecules and O2 molecules are similar; thus, the Raman cross section of N2 or O2 molecules can be used to compute the approximate Ring effect for simplicity.

心电散点图解析策略之恒变微分法

目的探讨RR间期的恒变性质对心电散点图位置及走向的影响,总结恒变微分法在快速分析动态心电图中的应用与分析技巧。方法结合室性早搏、室性早搏连发、房性早搏等经典病例的RR间期特征,分析其散点图特征点集的位置及走向与RR间期恒变性质的关系,总结恒变微分法的解析策略。结果时间散点图中RR间期为恒量时呈水平走向(如NV、VV层等),为变量时则呈上、下起伏(如NN、SN、VN层等)。Lorenz散点图中横坐标为恒量时,特征点集垂直分布(如NVN、VVN点集等),纵坐标为恒量时,特征点集水平分布(如NNV、VNV点集等),横、纵坐标均为恒量时特征点集局限性分布(如NVV、VVV点集等);横、纵坐标均为变量时,特征点集倾斜分布(如VNN、NNN点集等),且根据微分学原理,其主轴斜率取决于两变量的系数之比。结论RR间期的恒变性质决定了心电散点图的位置及走向。通过散点图技术快速识别的恒量与变量可以揭示心律失常的部分电生理机制,类似于天然的电生理检查。恒变微分法是解析心电散点图的有效方法,更是快速分析动态心电图的基本技能。

利用偏振图像加权融合及CLAHE算法的水下成像方法

针对传统基于偏振差分原理的水下光学成像方法中,由于目标退偏振特性差异引起的图像中局部反射光损失的问题,提出了基于偏振图像加权融合与限制对比度自适应直方图均衡(CLAHE)算法的水下成像方法。一方面,将原始水下图像分解为偏振光强图像和非偏振光强图像,根据不同退偏振特性目标在两幅图像中的灰度值分布特点,设计相应的权重因子,对两幅图像进行加权融合,从而实现在压缩原始水下图像中散射光的同时保留更多目标反射光,提升整体目标反射光在融合图像中所占的比例。另一方面,为了进一步提升融合图像的对比度,利用CLAHE算法对融合图像进行处理。该算法能够在提升融合图像对比度的同时,有效避免图像噪声的放大。实验结果表明,相较于传统的偏振差分方法以及独立的直方图均衡算法,该算法能够有效提升水下图像的清晰度和对比度。

玉林市2023年3月25日冰雹过程双偏振雷达特征分析

利用常规气象观测资料和双偏振雷达资料,采用天气诊断分析方法,分析玉林市2023年3月25日冰雹过程的成因和双偏振雷达特征。结果表明:(1)此次冰雹天气是受高空槽、低层切变线和地面冷空气共同影响产生。(2)反射率因子强度均>60 dBZ,低层有入流缺口、有界弱回波区、三体散射和旁瓣回波等特征,中气旋厚度较厚,维持时间长。(3)上升气流中存在一定数量的液态雨滴和冰晶粒子;0℃层以下有一定数量的液态粒子和湿冰粒子,而0℃层以上有较大尺寸的冰晶粒子。

土壤表面与矩形截面柱宽带差值散射场研究

基于地物表面上方雷达目标检测、识别和分类等应用需求,采用指数型分布粗糙面和蒙特卡罗方法模拟土壤表面,用四成分模型表示土壤的介电特性,运用时域有限差分法将差值场散射理论加入到计算模型中,研究了土壤表面与矩形截面柱的宽带复合电磁散射特性,得到了差值雷达散射系数的频率响应曲线,分析了入射角,矩形截面柱倾角、中心距土壤表面的高度、长和宽及尺寸对差值雷达散射系数的影响。计算结果表明,差值雷达散射系数随频率振荡地变化,入射角、矩形截面柱倾角对差值雷达散射系数的大小影响较大且较为复杂;矩形截面柱中心距土壤表面的高度对差值雷达散射系数的大小影响不大,但对频率响应曲线的振荡幅度影响较大,并且随频率的增大而影响减小;矩形截面柱长边长度对于差值雷达散射系数的影响较小,宽边长度对差值雷达散射系数的影响较大且较为复杂,等比例放大矩形截面柱对差值雷达散射系数的影响较大且较为复杂。研究结果可为民用、军用领域工程提供理论依据和实践方法。

Elastic scattering based on energy-dependent relativistic Love-Franey model at energies between 20 and 800 MeV

In order to investigate the elastic scattering,we fit scattering observables of the weighted fits(WF16)with the relativistic Love-Franey(RLF)model.The masses,cutoff parameters,and initial coupling strengths of RLF are assumed to be independent of energy.Because the energy boundary between low energy and high energy is around 200 Me V,the masses,cutoff parameters,and initial coupling strengths of RLF are obtained by fitting scattering observables of WF16 at an incident energy of 200 MeV.With the masses,cutoff parameters,and initial coupling strengths as the input,the energy-dependent RLF model is constructed over the laboratory energy range of 20 to 800MeV within a unified fit.To examine the validity of this fit,we investigate p+^(208)Pbelastic scattering for various energies.Although the scattering observables of pp and pn of 200 MeV best fit the values of WF16,the RLF model of 200 MeV without the Pauli blocking(PB)corrections fails to describe the experimental differential cross sections,analyzing powers,and spinrotation functions.When the PB corrections are taken into account for various energies,the RLF model can well describe the experimental data of p+^(208)Pbelastic scattering.

烧结工艺对聚四氟乙烯长丝力学性能的影响

采用差示扫描量热仪、小角/广角X射线散射仪、万能材料试验机等,研究了烧结过程中温度、时间及冷却方式对聚四氟乙烯(PTFE)长丝结构与力学性能的影响;进一步探究了长丝成型加工过程中拉伸比的影响。结果表明,烧结温度过低,结晶度较高,而烧结温度过高,材料过度烧结导致结晶度下降;断裂强力随温度升高呈现先上升后下降趋势,断裂伸长率明显降低。烧结时间不同,结晶度变化较小,但断裂强度和断裂伸长率均随时间延长而降低。退火制品结晶度高,拉伸强度大,断裂伸长率低;而淬火制品结晶度较低,力学性能较差。其次,随着拉伸比增加,结晶度降低,取向度提高,部分非晶态链沿拉伸轴定向排列,使得长丝断裂强力明显提高,断裂伸长率明显降低。

省域循环经济发展动态分析及差异研究

循环经济发展对加快国民经济体系协调畅通、经济社会事业可持续快速发展具有举足轻重的作用。以2016年至2021年我国30个省域为研究对象,构建了循环经济发展测度指标体系,运用纵横向拉开档次法确定了指标权重,得出了2016年至2021年循环经济发展测度值,并利用非线性规划法结合TOWA-GA混合算子求出循环经济发展的综合指数值,衡量了省域循环经济发展状况排名的波动数值和方向,最后分析了各省循环经济发展的阻碍因素并提出了相应的对策建议。