Revisiting the Electron Radius in Light of Length Contraction

In previous work, the electron radius was identified as the “actual electron radius.” However, this is more accurately described as the electron radius at rest. This study reexamines the electron with an emphasis on the electron radius under motion, incorporating the effects of length contraction. The findings suggest that the radius is subject to Lorentz contraction, which has interesting implications for relativistic effects at the subatomic level.

Sensitivity of the Grid-point Atmospheric Model of IAP LASG(GAMILI.I.0)Climate Simulations to Cloud Droplet Effective Radius and Liquid Water Path

This paper documents a study to examine the sensitivity to cloud droplet effective radius and liquid water path and the alleviation the energy imbalance at the top of the atmosphere and at the surface in the latest version of the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP） （GAMIL1.1.0）. Considerable negative biases in all flux components, and thus an energy imbalance, are found in GAMIL1.1.0. In order to alleviate the energy imbalance, two modifications, namely an increase in cloud droplet effective radius and a decrease in cloud liquid water path, have been made to the cloud properties used in GAMIL. With the increased cloud droplet effective radius, the single scattering albedo of clouds is reduced, and thus the reflection of solar radiation into space by clouds is reduced and the net solar radiation flux at the top of the atmosphere is increased. With the reduced cloud optical depth, the net surface shortwave radiation flux is increased, causing a net warming over the land surface. This results in an increase in both sensible and latent heat fluxes over the land regions, which is largely balanced by the increased terrestrial radiation fluxes. Consequently, the energy balance at the top of atmosphere and at the surface is achieved with energy flux components consistent with available satellite observations.

Coupling mechanism of THM fields and SLG phases during the gas extraction process and its application in numerical analysis of gas occurrence regularity and effective extraction radius

The analysis of the coupling mechanism of thermal-hydraulic-mechanical(THM)fields,and solid-liquidgas(SLG)phases during gas extraction process is of profound significance to explore its numerical application in the gas occurrence regularity and its effective extraction radius.In this study,the Hudi coal mine in Qinshui basin is taken as the research area,the influencing factors of gas occurrence were analyzed,the differences in overburden load for gas pressure distribution and the factors influencing the effective extraction radius were further discussed by using the COMSOL software.The results show that the derivation of mathematical model in gas extraction shows that the process is a process the THM fields restrict each other,and the SLG phases influence each other.The longer the extraction time,the larger the influencing range of borehole,and the better the extraction effect.The larger the diameter of borehole,the larger the effective extraction radius,and the influence on gas extraction effect is smaller in the early stage and larger in the late stage.The borehole arrangement should be flexibly arranged according to the actual extraction situation.The higher the porosity,the higher the permeability,the better the gas extraction effect.The larger the overburden load of reservoir,the stronger the effective stress,which will result in the more severe the strain,and the closure of pore and fracture,which in turn will lead to the decrease of permeability and slow down the gas extraction.The relationship among extraction time,borehole diameter,negative pressure of gas extraction,permeability with effective extraction radius is exponential.This study has important theoretical and practical significance for clarifying and summarizing the gas occurrence regularity and its engineering practice.

Effect of the Injected Plasma on the Effective Radius of the Magnetic Bubble

Effect of the injected plasma on the effective radius of the magnetic bubble in plasma sail is discussed. Results from solving both the two-dimensional magneto-hydrodynamic（MHD） equations and the magnetic flux conservation equation indicate that the effective radius of the magnetic bubble formed by the pure dipole field is very small, and the rate of the falloff of the magnetic field can be effectively reduced by the inflation of the high-density plasma. The falloff rate of the magnetic field can be r^-1.4. The effective radius of the magnetic bubble can hence be 8.2 km. The effective radius of the magnetic bubble increases about thirty-six times, comparing to the case of the pure dipole field.

Some features of effective radius and variance of dust particles in numerical simulations of the dust climate on Mars

Airborne dust is an important constituent in the Martian atmosphere because of its radiative interaction with the atmospheric circulation.Dust size is one crucial factor in determining this effect.In reality dust sizes are varied;however,in numerical modeling of dust processes,dust size has usually been described by choice of a particular size distribution function,or by use of fixed values of effective radius(ER)and effective variance(EV).In this work,we present analytical expressions that have been derived to specify ER and EV for Nbin dust schemes,based on a model-calculated dust mixing ratio.Numerical simulations based on this approach thus would consider the effects of variable ER on the atmospheric radiation and their interaction.Results have revealed some interesting features of the dust distribution parameters,such as seasonal and spatial variation of ER and EV,which are generally consistent with some previous observational and modeling studies.Compared with the usual approach of using a fixed ER,simulation results from the present approach suggest that the variability of ER can have significant effects on the simulated thermal field of the Martian atmosphere.

The influence of defects on the effective Young's modulus of a defective solid

It is difficult to establish structure-property relationships in a defective solid because of its inhomogeneous-geometry microstructure caused by defects. In the present research, the effects of pores and cracks on the Young’s modulus of a defective solid are studied. Based on the law of the conservation of energy, mathematical formulations are proposed to indicate how the shape, size, and distribution of defects affect the effective Young’s modulus. In this approach, detailed equations are illustrated to represent the shape and size of defects on the effective Young’s modulus. Different from the results obtained from the traditional empirical analyses, mixture law or statistical method, for the first time, our results from the finite element method （FEM） and strict analytical calculation show that the influence of pore radius and crack length on the effective Young’s modulus can be quantified. It is found that the longest crack in a typical microstructure of ceramic coating dominates the contribution of the effective Young’s modulus in the vertical direction of the crack.

Finite Larmor radius magnetohydrodynamic analysis of the ballooning modes in tokamaks

In this paper, the effect of finite Larmor radius （FLR） on high n ballooning modes is studied on the basis of FLR magnetohydrodynamic （FLR-MHD） theory. A linear FLR ballooning mode equation is derived in an ＇s^-- α＇ type equilibrium of circular-flux-surfaces, which is reduced to the ideal ballooning mode equation when the FLR effect is neglected. The present model reproduces some basic features of FLR effects on ballooning mode obtained previously by kinetic ballooning mode theories. That is, the FLR introduces a real frequency into ballooning mode and has a stabilising effect on ballooning modes （e.g., in the case of high magnetic shear s^- ≥ 0.8）. In particular, some new properties of FLR effects on ballooning mode are discovered in the present research. Here it is found that in a high magnetic shear region （s^- ≥ 0.8） the critical pressure gradient （αc,FLR） of ballooning mode is larger than the ideal one （αc,IMHD） and becomes larger and larger with the increase of FLR parameter b0. However, in a low magnetic shear region, the FLR ballooning mode is more unstable than the ideal one, and the αc,FLR is much lower than the αc,IMHD. Moreover, the present results indicate that there exist some new weaker instabilities near the second stability boundary （obtained from ideal MHD theory）, which means that the second stable region becomes narrow.

Earthquake-Affected Time-Space Domain, Recurrence Interval and Effective Preparation Time of Earthquakes

The study shows that earthquake-affected time-space domain (ETSD), i.e. a time-space range in which strong earthquakes are unable to occur owing to the influence of a prior earthquake occurring, shows a hyperbolic margin curve in the t(time)-r(distance) coordinate plane, which has a maximum affected radius r 0 at t=0 and a maximum influence time t 0 (i.e. the in-situ recurrence interval of earthquakes) at r=0. Based on the time-distance distributions of posterior earthquakes relative to prior ones in the regions of North China, Northwest China, Qinghai-Xizang (Tibet) plateau and Southwest China, the optimized and 90%-confidence margin curves are estimated using optimization and statistical analysis methods. This indicates that the concept and method of ETSD with 3-dimension (time-distance-magnitudes) instead of those of “recurrence interval" with 1-dimension (time) or 2-dimension (time-magnitude) provides a new approach to understanding the fluctuation of seismic activities, estimating the effective earthquake-preparation time of potential hypocenters, and therefore improving the medium- and long-term prediction of strong earthquakes.

SYNERGETIC MITIGATION OF THE RAYLEIGH-TAYLORINSTABILITY BY SHEAR AXIAL FLOWS ANDFINITE LARMOR RADIUS

A hybrid model of MHD and kinetic theory is proposed to investigate the synergetic stabilizing effects of sheared axial flow and finite Larmor radius on the RayleighTaylor instability in Zpinch implosions.In our model the MHD plasma is considered to respond to a perturbation with exp at frequency ω+ik2⊥ρ2iΩi instead of frequency ω,where k2⊥ρ2i is the finite Larmor radius effects given from the general kinetic theory of magnetized plasma.Therefore linearized continuity and momentum equations include automatically the finite Larmor radius effects.Dispersion relation is derived,which includes the effects of a density discontinuity and the finite Larmor radius as well as a sheared flow that produces the KelvinHelmholtz instability.The dispersion equation is examined in three cases.The results indicate that the synergetic effect of sheared axial flow and the finite Larmor radius can mitigate both the RayleighTaylor instability and the hybrid RayleighTaylor/KelvinHelmholtz instability.Moreover,the synergetic mitigation effect is stronger than either of them acting separately.

The Refractive Effect of k-Factor on Radio Propagation over Lokoja, Nigeria

The effective earth radius factor(k-factor)has a refractive propagation effect on transmitted radio signals thus making its study necessary for the proper planning of terrestrial radio links and power budget.This study was carried out over the city of Lokoja,Nigeria,using ten years(2011 to 2020)atmospheric data of temperature,pressure and humidity both at the surface(12 m)and at 100 m AGL.The data were retrieved from European Centre for Medium-Range Weather Forecasts(ECMWF)ERA5.The k-factor yearly variation follows the same trend with minimum and maximum values obtained during dry and wet season months respectively.In addition,the highest mean value of 1.00042 was recorded in the month of August while the lowest value of 1.00040 was recorded in the month of January with an overall mean value of 1.0003.This value is less than the recommended standard of 1.33 by ITU-R.The propagation effect corresponding to k<1.33 is sub-refractive.The implication of this on radio wave propagation,especially terrestrial communications is that transmitted wireless signal is prone to losses.This can be mitigated through an effective power budget:Choice of transmitting antenna’s height and gain,so as to improve the Quality of Service over the study area.

指套牵引联合手法复位外固定治疗老年桡骨远端骨折的临床效果

目的:对比指套牵引联合手法复位外固定与单纯手法复位外固定治疗老年桡骨远端骨折的临床疗效。方法:选取2022年3月—2023年3月于天津大学天津医院就诊的老年桡骨远端骨折患者1000例,以随机数字表法均分为指套牵引联合手法复位组和单纯手法复位组。在手法复位后2 d、1周、2周、4周、8周、12周及20周对两组患者的腕关节活动度、疼痛评分、Gartland-Werley腕关节功能评分进行比较。结果:排除脱落病例后,指套牵引联合手法复位组纳入487例,手法复位组491例。相比于单纯手法复位,指套牵引联合手法复位显著提升了背伸(P=0.024)、尺偏(P<0.001)、掌屈(P=0.003)活动度,降低了复位8周(P<0.001)、12周(P=0.022)、20周(P=0.002)时患者的Gartland-Werley腕关节功能评分,但没有显著抑制随访期中患者的主观疼痛。结论:指套牵引联合手法复位外固定可部分地提高老年桡骨远端骨折患者复位后腕关节的活动度及功能。

考虑外包滤料影响的暗管排水工程设计与计算

针对农田暗管排水工程设计中忽略外包滤料影响的实际情况,以宁夏银北灌区暗管排水项目为背景,依据Widmoser提出的“有效半径”理念,计算了考虑外包滤料暗管的水力要素,对比分析了考虑外包滤料与不考虑外包滤料的暗管间距计算结果,通过渗流槽物理模型试验并构建数值模型进行模拟分析验证。在此基础上,采用相关分析法给出暗管工程设计参数与暗管排水流量之间的灰色关联系数。结果表明:在工程案例的非稳定渗流计算中,考虑外包滤料影响的暗管间距较未考虑外包滤料的暗管间距相差27.239%;外包滤料厚度、暗管间距与排水流量的灰色关联度分别为0.741和0.739,外包滤料厚度与排水流量间的相关性更为显著。在回归水再利用背景下,设置复合型外包滤料的农田暗管排水工程水力计算中,建议应计入外包滤料的影响。

新型弧形板簧支撑非充气轮胎的有限元分析

设计一种以弧形等厚板簧为主要承载部件的新型非充气轮胎,建立其有限元模型,仿真模拟静态径向加载与稳态纯滚动工况,得出轮胎径向刚度和径向力,对接地压力参数进行评价,计算出轮胎有效滚动半径。结果表明:在静态径向加载条件下,轮胎径向力与径向位移近似线性正相关,径向刚度和径向力随板簧厚度增大而增大;轮胎接地印痕中心出现应力集中现象,板簧越厚则平均接地压力越大,胎面不均匀磨损程度越高;轮胎有效滚动半径随径向负荷增大线性减小。本研究可为非充气轮胎性能分析或者结构优化提供参考。

微重力下火箭推进系统液氧贮箱内气泡脱离半径研究

研究微重力下液氧贮箱内气泡脱离半径是运载火箭推进系统推进剂在轨沸腾与换热计算的基础.与常重力和低重力环境不同,微重力下Marangoni效应变得突出.为了求解气泡脱离半径,构建包含浮力、惯性力、压差力、表面张力、黏性阻力和Marangoni力的气泡动力学模型.针对现有Marangoni力计算公式适用范围狭窄的问题,依托数值仿真方法,拟合得到了更精确的修正因子计算公式,进而扩充了Marangoni力计算模型的适用范围.使用运载火箭液氧贮箱常规工作压力0.3 MPa下的饱和液氧物性参数,计算得到气泡所受合力随半径的变化关系以及气泡脱离半径随重力的变化关系.结果表明,气泡的脱离行为可以由微重力区、过渡区和低重力区三个区域来划分.微重力区内可以形成厘米级甚至米级的大气泡,而低重力区内只能形成0.1 mm级的小气泡.相比之前的模型,本文模型可以同时适用于三个区,更全面地揭示了微重力下液氧贮箱内的气泡脱离特性,可以为液氧贮箱换热特性分析提供理论支撑.

Discharge evolution law of debris flow based on a sharp bend physical modeling test

For the basins with debris flow development,its channel terrain exhibits a tortuous shape,which significantly restricts the movement of debris flows and leads to severe erosion effects on the concave bank.Therefore,this study aims to analyze the shear force of debris flows within the bend channel.We established the relationship between the shear force and bend curvature through laboratory experiments.Under the long-term erosion by debris flows,the curvature radius of bends gradually increases,however,when this increasing trend reaches an equilibrium state with the intensity of debris flow discharge,there will be no significant change in curvature radius.In general,the activity pattern and discharges of debris flows would remain relatively stable.Hence,we can infer the magnitude of debris flow discharges from the terrain parameters of the bend channel.

An improved effective liquid drop model for cluster radioactivity

The effective liquid drop model(ELDM)is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency.Within the improved effective liquid drop model(IMELDM),the experimental cluster radioactivity half-lives of the trans-lead region are calculated.It is shown that the accuracy of the IMELDM is improved compared with that of the ELDM.At last,the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead nuclei are predicted by the IMELDM.These predictions may be useful for searching for new candidates for cluster radioactivity in future experiments.

小半径曲线节段拼装箱梁设计和施工关键技术研究

为推动小半径曲线节段拼装箱梁在立交匝道桥梁中的应用,对该类桥梁受力特性、合理构造以及梁段制造、架桥机施工、拼装线形控制等关键技术进行研究。分析曲线半径对该类箱梁弯扭耦合和湿接缝受力的影响;研究梁高、腹板厚度和顶、底板厚度对梁剪扭承载力的影响;为适应平面曲线行走和吊装的需求,总结架桥机拼装施工过程中主要采用的转弯过孔、偏位和斜置起吊调整以及尾部喂梁关键技术;分析拼装过程中产生的轴线偏差和横向位移及线形控制措施。结果表明:曲线半径小于250 m的节段拼装箱梁需考虑弯扭耦合作用,曲线半径小于100 m时湿接缝截面的抗扭承载力和剪扭允许应力已不能满足要求;提高截面抗剪扭承载力最有效的构造措施是增加腹板厚度,其次是增加顶、底板厚度;曲线半径越小,小半径节段梁拼装轴线偏差越大、轴线横向位移越大,应根据曲线半径来规定安装精度验收标准、根据成桥轴线横向变形设置横向预拱度。

基于钻孔周边瓦斯压力的有效抽采半径精细化数值解算方法

针对煤层钻孔有效抽采半径表征不明晰的问题,首先确定了有效抽采半径所对应的瓦斯压力临界值,之后采用钻孔径向流场瓦斯压力表达式计算了钻孔周围瓦斯压力变化规律,通过现场实测数据验证了计算结果的可靠性,分析了抽采负压、透气性系数、钻孔半径、吸附常数等对煤层瓦斯压力分布的敏感性,最后根据临界瓦斯压力指标确定出了有效抽采半径,通过现场瓦斯瓦斯含量检测数据进行了验证,并推导了不同预抽时间下钻孔有效抽采半径与不同原始瓦斯压力的函数关系。研究结果表明,理论解算的瓦斯压力以及有效抽采半径值均与现场实测数据保持基本一致,瓦斯压力与抽采时间呈反比,与至钻孔的距离呈正比;抽采负压、透气性系数、钻孔半径、吸附常数b均与瓦斯压力呈负相关,吸附常数a则与瓦斯压力呈正相关;有效抽采半径随着抽采时间增加而增加,二者符合对数函数类型。通过推导出的有效抽采半径、预抽时间以及原始瓦斯压力函数关系式,能够方便快速计算得到对应的有效抽采半径,并确定合理的钻孔间距,对井下煤层瓦斯抽采钻孔精细化设计工作具有一定的理论意义。

北半球夏季热带和副热带昼间云粒子有效半径廓线特征的分析

云粒子有效半径是云微物理中的重要参数,准确获取云粒子有效半径的分布特征对分析云形成、降水及灾害性天气预报、地气辐射收支等都具有重要意义。利用1998~2012年6~8月(夏季)热带测雨卫星(Tropical Rain Measuring Mission,简称TRMM)搭载的可见光/红外扫描仪(Visible and Infrared Scanner,简称VIRS)的探测资料,分析了夏季热带和副热带地区云粒子有效半径的空间分布和廓线特征。结果表明云粒子有效半径在空间上分布不均匀,粒子尺度分布在5~30μm之间,局部尺度可达30μm以上,并且洋面的云粒子有效半径相比陆面的云粒子有效半径更大;标准差多分布在2~10μm之间,但局部可达10μm以上。不同区域的云粒子有效半径垂直廓线分布表明,随着亮温的降低,云粒子有效半径先增后减;对于小的云粒子有效半径,洋面比陆面的云粒子有效半径廓线大,且北半球副热带比南半球副热带的云粒子有效半径廓线大;对于大的云粒子有效半径,各区域间的云粒子有效半径廓线差异较小;云粒子有效半径标准差廓线分析表明,小粒子、适中粒子和大粒子的标准差大值分别位于冰云、混合云和水云区。本研究结果为模式模拟热带和副热带区域云中粒子有效半径分布特征提供了观测依据。

温度效应下小半径曲线桥梁轨作用及扣件阻力影响研究

为研究温度效应对小半径曲线桥梁轨相互作用的影响,以某小半径有轨电车曲线桥为背景,建立考虑无缝线路线形的线-桥-墩一体化空间有限元模型并进行验证。分析并对比直线桥与小半径曲线桥梁轨相互作用规律,研究了整体升温工况与局部升温工况下小半径曲线桥钢轨伸缩附加力、桥梁墩顶横向力和纵向力的大小及其分布规律,提出3种扣件布置方案并从减小钢轨伸缩附加力的角度进行对比。研究结果表明:相较于直线桥,整体升温情况下小半径曲线桥上钢轨横向位移及墩顶横向力均较大;对于小半径曲线桥,整体升温情况下,随着桥梁温度的升高,钢轨的伸缩附加力逐渐增大;采用整体升温工况进行设计检算时,钢轨所受伸缩力及墩顶纵向力与局部升温工况相比结果偏大;相较于铺设常阻力扣件,铺设小阻力扣件可以明显减小钢轨伸缩附加力,但纵向阻力过小容易导致钢轨折断时断缝过大。研究结果可以为有轨电车小半径曲线桥上无缝线路的设计提供理论参考。