New spraying process development for inlet deflector roller in a recoiling line

The inlet deflector rollers of a recoiling line are sprayed rollers. Short scratch lines have been found on the surface of steel sheets during commissioning. By adjusting the control parameters of the line and investigating the manufacturing process of inlet deflector rollers, the root cause of the scratches was found. By modifying the manufacturing process of the rollers, the scratches have been thoroughly eliminated, and quality steel sheets have been consistently produced in the recoiling line.

Decay study of ^(20)Na and its beta-delayed ^(16)O recoiling

The decay of 20Na of astrophysical reactions has been studied deeply via 20Ne(p, n)20Na reaction. A new β-delayed α decay with α energy of 5 896 ± 6 keV and relative intensity of 0. 002 4 ± 0. 000 3 was discovered. At the same time the 16O recoiling in β+-delayed α decay of 20Na was observed in experiment for the first time. From these, it is inferred that a β-delayed low energy α decay of 20Na with energy of-780 keV and relative intensity of -1.4 was mixed in 16O recoiling. In 16O recoiling and the low energy α decay, the energy loss for low energy charged particles through matter was discussed in detail. At last, two methods for discriminating the β-delayed low energy α decay of 20Na were proposed.

Study of relationship between motion of mechanisms in gas operated weapon and its shock absorber

The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the weapon.Earlier works,which did not consider the dynamic properties of the base of the weapon,did not allow to reconcile the calculated and experimental results of the weapon casing displacement when shooting from firing rests.For the analysis of the motion of individual parts,the methods of mathematical modelling and firing experiments using a high-speed camera were chosen.Calculations show the best accord with experiment when modelling the system with 4 degrees of freedom.The oscillation of the system regarding the movement of the breech block carrier and the weapon casing was investigated under changed conditions of rate of fire,the use of a muzzle brake and different types of shock absorbers.The velocities and displacements of the weapon casing and the breech block carrier at different values of the impulse of the gases to the breech block carrier were determined.

Computational Analysis of Selective Laser Sintering of Inconel 625

A two-dimensional multi-physics finite element model is developed to simulate the Selective Laser Sintering(SLS)process using Inconel 625 powders.The validity of the developed model is first assessed by comparing its results with experimental data.Various factors such as phase transition,recoil pressure,surface tension,and theMarangoni force are considered.The study’s findings underscore that the morphology and thermal-fluid dynamics of the molten pool in the SLS process are predominantly shaped by the influence of the Marangoni force and recoil pressure acting on its surface.The recoil pressure at the front of the laser spot rises exponentially with temperature,making the liquid metal move downward,and creating a depression at the pool’s head.It also causes particles to splash from the pool’s rear edge.The study explores the influence of the backward Marangoni force,where hightemperature liquid flows from the front to the rear of the molten pool,creating a vortex and moving the pool in the rear.Process parameters like laser intensity,scan speed,and spot size were analyzed.The findings indicate that higher laser power lower scanning speed and laser beam spot size lead to increased width and depth of the molten pool.

BBK模型中非一阶效应和交换效应的理论研究

用BBK模型和修正后的BBK模型对低能、共面非对称几何条件下电子离化氢原子的三重微分散射截面进行了计算,并把结果与一级玻恩近似下的计算结果以及实验数据进行了比较,对修正后的BBK模型中非一阶效应和交换效应进行了分析和探讨.发现该模型中末态三体间的屏蔽包含了极强的非一阶效应信息.

低能氢原子(e,2e)反应中非一阶效应的理论研究

用BBK模型和修正后的BBK模型对入射能为27.2eV时,共面非对称几何条件下电子离化氢原子的三重微分散射截面进行了计算,并把结果与一级玻恩近似下的计算结果以及实验数据进行了比较,对修正后的BBK模型中非一阶效应进行了分析和探讨.

C^(6+)单离化氦原子反应TDCS的分析与讨论

在共面非对称几何条件下,将能壳上跃迁矩阵元表示为结构因子和末态道两粒子间关联因子的乘积,推导出C6+离化He原子在不同动量转移下三重微分散射截面解析表达式,分析了实参数和有效电荷对散射截面角分布的影响.

正交投影对三重微分散射截面(TDCS)的影响

从跃迁矩阵元的后滞形式出发,计算了在入射能量为150 eV,敲出能量分别为3 eV和5 eV,散射角1θ=16°的TDCS.取末态波函数为库仑波函数和平面波函数的乘积;初态波函数为平面波、类氢离子基态波和库仑因子C12的乘积;通过正交投影使跃迁矩阵元的后滞形式第一项为零,另外还考虑了屏蔽效应,这样所得出的理论计算结果与实验数值符合的更好了.

C^(6+)单离化氦原子反应TDCS的研究

在共面非对称几何条件下,分析了C6+离化He原子在出射电子能量为E2=1eV,动量转移分别为0.45a.u.、0.65a.u.和1.0a.u.时的三重微分散射截面,讨论了不同动量转移下的三重微分散射截面随散射角的曲线变化,得到了与实验结果比较相似的结果.

由Recollement导出的t-结构的非退化性和有界性

根据Beilinson A,Bernstein J,Deligne P的结论可知,若三个三角范畴允许有一个Recollement,则Recollement两端三角范畴上的t-结构可以诱导中间三角范畴上的一个t-结构.在这篇文章中讨论了这三个t-结构在非退化性和有界性上的联系.首先证明了两端三角范畴上的t-结构是非退化的当且仅当中间三角范畴上的t-结构是非退化的.其次证明了两端三角范畴上的t-结构是有界的当且仅当中间三角范畴上的t-结构是有界的.最后讨论了Recollement函子的t-正合性.

电子碰撞电离氦原子的三重微分截面

在一级玻恩近似理论框架下,用分波法计算入射电子能量分别为634.59、604.59、400、250、150 eV的氦原子(e,2e)反应的三重微分截面(TDCS),并与实验结果进行比较.在入射电子能量为604.59、400、250 eV情况下,全扭曲波玻恩近似与实验较为符合;在入射电子能量为634.59 eV情况,其敲出电子能量40 eV条件下,考虑敲出电子库仑势的计算结果好于考虑敲出电子扭曲势的计算结果.在固定散射角情况下,Recoil峰的相对强度和Binary峰值位置随敲出电子能量变化的趋势,与文献(Ehrhatdt H,Hesselbacher K H,Jung K,et al.Collisional ionization of helium by 250 eV electrons:experiments with completely determined kinetics[J].J Phys B:At Opt Mol Phys,1972,5:2107-2116)中提到的变化趋势一致.

A prediction method for the performance of a low-recoil gun with front nozzle

One of the greatest challenges in the design of a gun is to balance muzzle velocity and recoil,especially for guns on aircrafts and deployable vehicles.To resolve the conflict between gun power and recoil force,a concept of rarefaction wave gun(RAVEN)was proposed to significantly reduce the weapon recoil and the heat in barrel,while minimally reducing the muzzle velocity.The main principle of RAVEN is that the rarefaction wave will not reach the projectile base until the muzzle by delaying the venting time of an expansion nozzle at the breech.Developed on the RAVEN principle,the purpose of this paper is to provide an engineering method for predicting the performance of a low-recoil gun with front nozzle.First,a two-dimensional two-phase flow model of interior ballistic during the RAVEN firing cycle was established.Numerical simulation results were compared with the published data to validate the reliability and accuracy.Next,the effects of the vent opening times and locations were investigated to determine the influence rules on the performance of the RAVEN with front nozzle.Then according to the results above,simple nonlinear fitting formulas were provided to explain how the muzzle velocity and the recoil force change with the vent opening time and location.Finally,a better vent venting opening time corresponding to the vent location was proposed.The findings should make an important contribution to the field of engineering applications of the RAVEN.

Numerical analysis of thermal fluid transport behavior during electron beam welding of 2219 aluminum alloy plate

A two-dimensional mathematical model based on volume-of-fluid method is proposed to investigate the heat transfer,fluidflow and keyhole dynamics during electron beam welding(EBW)on20mm-thick2219aluminum alloy plate.In the model,anadaptive heat source model tracking keyhole depth is employed to simulate the heating process of electron beam.Heat and masstransport of different vortexes induced by surface tension,thermo-capillary force,recoil pressure,hydrostatic pressure and thermalbuoyancy is coupled with keyhole evolution.A series of physical phenomena involving keyhole drilling,collapse,reopening,quasi-stability,backfilling and the coupled thermal field are analyzed systematically.The results indicate that the decreased heat fluxof beam in depth can decelerate the keyholing velocity of recoil pressure and promote the quasi-steady state.Before and close to thisstate,the keyhole collapses and complicates the fluid transport of vortexes.Finally,all simulation results are validated againstexperiments.

Coupling Effects of A Deep-Water Drilling Riser and the Platform and the Discharging Fluid Column in An Emergency Disconnect Scenario

As drilling operations move into remote locations and extreme water depths, recoil analysis requires more careful considerations and the incidence of emergency disconnect is increased inevitably. To accurately capture the recoil dynamics of a deep-water riser in an emergency disconnect scenario, researchers typically focus on modelling the influential subsystems (e.g., the tensioner, the mud discharge and seawater refilling process) which can be solved in the preprocessing, and then the determined parameters are transmitted into an existing global riser analysis software. Distinctively, the current study devotes efforts into the coupling effects resulting from that the suspended riser reacts the platform heave motion via the tensioner system in the course of recoil and the discharging fluid column follows the oscillation of the riser in the mud discharge process. Four simulation models are established based on lumped mass method employing different formulas for the top boundary condition of the riser and the discharging flow acceleration. It demonstrates that the coupling effects discussed above can significantly affect the recoil behavior during the transition phase from initial disconnect to the final hang-off state. It is recommended to develop a fully- coupled integrated model for recoil analysis and anti-recoil control system design before extreme deep-water applications.

Complex experimental analysis of rifle-shooter interaction

In this study, a complex analysis of a man-weapon interaction based on experimental effort is presented.The attention is focused on how a shooter can influence on a rifle, opposite to generally considered in literature rifle's impact on a shooter. It is shown, based on the kbk AKM weapon, that each support point of the rifle has an substantial impact on the system. It is said that identifying human reactions on weapon may let to describe gun movement and thus may be applied to weapon accuracy determination.

Investigation of enhancement in planar fast neutron detector efficiency with stacked structure using Geant4

Geant4 based Monte Carlo study has been carried out to assess the improvement in efficiency of the planar structure of Silicon Carbide(SiC)-based semiconductor fast neutron detector with the stacked structure. A proton recoil detector was simulated, which consists of hydrogenous converter, i.e., high-density polyethylene(HDPE) for generating recoil protons by means of neutron elastic scattering(n, p) reaction and semiconductor material SiC, for generating a detectable electrical signal upon transport of recoil protons through it. SiC is considered in order to overcome the various factors associated with conventional Si-based devices such as operability in a harsh radiation environment, as often encountered in nuclear facilities. Converter layer thickness is optimized by considering 10~9 neutron events of different monoenergetic neutron sources as well as ^(241)Am-Be neutron spectrum. It is found that the optimized thickness for neutron energy range of 1–10 MeV is ~400 μm. However, the efficiency of fast neutron detection is estimated to be only 0.112%,which is considered very low for meaningful and reliable detection of neutrons. To overcome this problem, a stacked juxtaposition of converter layer between SiC layers has been analyzed in order to achieve high efficiency. It is noted that a tenfold efficiency improvement has been obtained—1.04% for 10 layers stacked configuration vis-à-vis 0.112% of single converter layer detector. Further simulation of the stacked detector with respect to variable converter thickness has been performed to achieve the efficiency as high as ~3.85% with up to 50 stacks.

Ag^+(4d^(10))离子三重微分截面的研究

用自旋平均静态交换势下的三体扭曲波波恩近似计算了d轨道电子 (Ag+ (4d10 ) )在共面非对称几何条件下的三重微分截面 ,结果表明在高入射能的条件下 ,随散射电子角度θa的增加 ,bina ry峰和recoil峰分裂的个数都会增加 ,电子的电离振幅会随之下降 ,d电子的三重微分截面比s。

Measurement of the prompt neutron spectrum from thermalneutron-induced fission in U-235 using the recoil proton method

A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included.

Average Energy Loss Measured in Single and Double Electron Capture Collisions of He^2＋ on Ar at Low Velocities ＊

Employing the recoil ion momentum spectroscopy we investigate the collision between He^2＋ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reaction channels. It is found that in most cases for single- and double-electron capture, the inner electron in the target atom is removed, the recoil ion is in singly or multiply excited states （hollow ion is formed）, which indicates that electron correlation plays an important role in the process. The captured electrons prefer the ground states of the projectile. It is experimentally demonstrated that the average energy losses are directly related to charge transfer and electronic configuration

Propagation of positive, negative, and recoil leaders in upward lightning flashes

Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagnetic field in rocket-triggered lightning and tower-initiated lightning discharges; available channel base current data recorded in rocket-triggered lightning are also used. The negative leaders propagate in a stepped fashion accompanied by many branches. The stems ahead of the negative leader tip determine the manner and direction of the leader propagation, and even the branching and winding of the lightning channel. The impulsive current, electromagnetic field, and related optical images suggest that the positive leader may develop in a step-like fashion at its initial stage of triggered lightning. However, the stepping processes of the positive leader are obviously different from those of the negative leader. Tower-initiated lightning revealed that the most conspicuous characteristics of the stepwise positive leader involve the intermittent brush-like corona zone in front of the leader tip and the luminosity enhancement of the channel behind the tip. In rockettriggered lightning flashes, the charge transferred during an individual step for the negative leader was nearly an order greater than for the positive counterpart. The successive streamers ahead of the leader tip are essential for both negative and positive leader propagation, and the stems could be formed from one or more streamers in the previous negative streamer zone with the main leader channel dim. High-resolution observation of tower lightning also revealed a new type of bidirectional recoil leader, with polarity contrary to the traditional one, traversing in negative channels associated with tower-initiated and rocket-triggered lightning.