Production of neutron-rich actinide isotopes in isobaric collisions via multinucleon transfer reactions

We systematically calculated the multinucleon transfer reactions of ^(208)Os,^(208)Pt,^(208)Hg,^(208)Pb,^(208)Po,^(208)Rn,^(208)Ra,and ^(132,136) Xe when bombarded on ^(232) Th and ^(248) Cm at Coulomb barrier energies within the dinuclear system model.These results are in good agreement with the available experimental data.The influence of Coulomb and shell effects on actinide production in these reactions has been rigorously studied.We calculated and analyzed the potential energy surface (PES) and total kinetic energy (TKE) mass distributions for the reactions involving ^(208)Hg,^(208)Pb,and ^(208) Po with ^(248) Cm and ^(232)Th.The PES and TKE spectra shed light on the fragment formation mechanisms in multinucleon transfer reactions,with clear indications of isospin and shell effects.The production cross sections for multinucleon transfer products show a strong dependence on isobar projectiles with a mass number A=208.Isobar projectiles with high N/Z ratios are advantageous for generating neutron-rich target-like fragments.Conversely,products induced by isobar projectiles with larger charge numbers tend to shift toward proton-rich regions.The intertwining of the Coulomb potential and shell effect is evident in the production cross sections of actinide isotopes.Drawing from reactions induced by radioactive projectiles,we anticipate the discovery of several new actinide isotopes near the nuclear drip lines,extending our reach into the superheavy nuclei domain.

Product polarization and mechanism of Li + HF(v=0, j=0) → LiF(v', j') + H collision reaction

A state-to-state dynamics analysis for the Li＋HF （v = 0, j = 0）→LiF （v’, j’）＋H collision reaction has been performed through quasiclassical trajectory （QCT） calculations. It is found that the differential cross section （DCS） of the LiF products from the title reaction is preferentially backward scattering for v’=0, yet forward scattering for v’=1 and 2. For v’=3, the DCS exhibits forward, backward, and sideways scatterings. The variation of the internuclear distances and angles along the propagation time reveals that more than 99.08% of reaction trajectories undergo the direct reaction mechanism. The values of the polarization parameters a1-{1} and a0{2} demonstrate that the product rotational angular moment j’ is not only aligned perpendicular to the reagent relative velocity vector k, but also oriented along the negative y axis. These product polarization results agree well with the recent quantum mechanical studies. The mechanism of these results was proposed and discussed in detail.

Enhanced single-nanoparticle collisions for the hydrogen evolution reaction in a confined microchannel

Single nanoparticle(NP)collisions technique has been widely employed in electrocatalysis.However,the short collision duration of single NPs hinders the further improvement in their electrocatalytic performance.Here,to increase the dynamic collision duration of single NPs in the electron tunneling region,enhanced near-wall hindered diffusion is introduced in the stochastic collision process by coupling a Au ultramicroelectrode(UME)with a confined microchannel.In the case of single palladium nanoparticle(Pd NP)collisions for the hydrogen evolution reaction(HER),the hydrodynamic trapping confined in the microchannel effectively permits the activation of the HER on the single Pd NPs.The microchannel-based Au UME is promising in the application of single-NP collisions to energy conversion.

Differential Cross Sections of F+HD→DF+H Reaction at Collision Energies from 3.03 meV to 17.97 meV

The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.

THEORETICAL INVESTIGATION OF COLLISION ENERGY EFFECT ON REACTION O(?) BARIUM WITH METHYL BROMIDE

The reac dynamics on Ba+BrCH_3→BaBr+CH_3 has been investigated in the first proposed potential energy surface of the generalized LEPS type,using the quasiclassical trajectory method.In simulation of the conditions in molecular beam experiments,the results of the present study show significant effect of the reagent collision energy on the dynamics of the reaction,and are in good agreement with the experimental ones.

Stereodynamics Study of Li+HF→LiF+H Reactions on X^2A’ Potential Energy Surface at Collision Energies below 5.00 kcal/mol

The product rotational polarizations of reaction Li-SHF→LiF-kH at different collision energies, as well as at the different vibrational states and rotational states, are calculated by using the quasi-classical trajectory method based on a new potential energy surface constructed by Aguado et al. [J. Chem. Phys. 119（2003） 10088]. We investigate the Mignment and the orientation of the product molecule by calculating the P（θr, φr） distribu- tions describing polar angle distribution, the P（θr） distributions describing the k-j＇ correlation and the P（φr） distributions describing the k-k＇-j＇ correlation. We also explore the dependence of reaction probabilities and cross sections on the rotational and vibrational quantum number of the title reaction. It is concluded that the vibrational state has more important impact on the angular distribution, reaction probability and cross section.

Reaction mode between Si and Fe and evaluation of optimal species in poly-silicic-ferric coagulant

A kind of Fe-polysilicate polymer, poly-silicic-ferric （PSF） coagulant was prepared by co-polymerization （hydroxylation of mixture of Fe^3＋ and fresh polysilicic acid （PS））, in which PSF0.5, PSF1 or PSF3 denotes Si/Fe molar ratio of 0.5, 1 or 3, respectively. The effects of Si/Fe ratio and reaction time （co-polymerization time or aging time） on the reaction mode between Si and Fe were studies, and the optimal species of PSF was evaluated by pH change during the preparation of PSF and coagulation tests. The results showed that the characteristics of PSF are largely affected by both reaction time and Si/Fe ratio. PSF is found to be a essential complex of Si, Fe, and many other ions. The reaction mode between Si and Fe differs with various Si/Fe ratios. The pH of PSF0.5, PSF1 or PSF3 tended to be stable when reaction time is 10, 25 or 55 rain, respectively, which is almost consistent with the time reaching the relative stable morphology that is just the optimal species of higher coagulation efficiency. The optimal reaction time reaching optimal species can be evaluated by measuring the pH change during the polymerization process.

Fast-scale border collision bifurcation in SEPIC power factor pre-regulators

In this paper we report a kind of fast-scale instability occurring in the single-ended primary inductance converter （SEPIC） power factor pre-regulator, which is designed to operate in discontinuous conduction mode. Main results are given by exact cycle-by-cycle computer simulations as well as theoretical analysis. It is found that the instability phenomenon manifests itself as a fast-scale bifurcation at the switching period, which implies the occurrence of border collision bifurcation, or is related to the transition of the regular operating mode of the SEPIC. According to the theoretical analysis and simulation results, the effects of parameters on system stability, and the locations of the bifurcation points are confirmed. Moreover, the effects of such an instability on power factor and switching stress are also discussed. Finally, the occurrence of the asymmetric bifurcation locations is investigated. The results show that this work provides a convenient means of predicting stability boundaries which can facilitate the selection of the practical parameters.

Reentry Attitude Tracking Control for Hypersonic Vehicle with Reaction Control Systems via Improved Model Predictive Control Approach

This paper studies the reentry attitude tracking control problem for hypersonic vehicles(HSV)equipped with reaction control systems(RCS)and aerodynamic surfaces.The attitude dynamical model of the hypersonic vehicles is established,and the simplified longitudinal and lateral dynamic models are obtained,respectively.Then,the compound control allocation strategy is provided and the model predictive controller is designed for the pitch channel.Furthermore,considering the complicated jet interaction effect of HSV during RCS is working,an improved model predictive control approach is presented by introducing the online parameter estimation of the jet interaction coefficient for dealing with the uncertainty and disturbance.Moreover,considering the strong coupling effect between the yaw channel and roll channel,a coupled model predictive controller is designed by introducing the feedback of sideslip angle into the roll control channel to eliminate the coupling effect.Finally,the comparison simulations using the classical control method,MPC and IMPC approach are given to demonstrate the effectiveness and efficiency of the presented IMPC scheme.

Methodology of Wavelets in Relativistic Heavy Ion Collisions in One Dimensional Phase Space (<i>η</i>-Space)

An attempt has been made to apply the wavelet methodology for the study of the results of the chaotic behavior of multiparticle production in relativistic heavy ion collisions. We reviewed the data that describes the collisions of relativistic heavy ion for the case η-space in 1-D phase space of variable. We compared the experimental data and UrQMD data using wavelet coherency. We discussed the results of the comparison.

Defect-free surface of quartz glass polished in elastic mode by chemical impact reaction

Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.

Shape Evolution of the Compound Nucleus in the Superheavy Element Synthesis Reaction via the BUU Model

By taking the BUU model, we simulate the superheavy element synthesis reaction. With the rotation effect being included in the BUU model, the effect of the non-centrality of the reaction ^48Ca＋^238U→^286 112 is studied. It is shown that the promising impact parameter in the synthesis process can be released from zero to a value little smaller than the radius of the smaller nucleus involved in the reaction. Meanwhile, the compound nucleus may involve rich shape phases.

Mode Specificity Dynamics of Prototypical Multi-Channel H+CH_(3)OH Reaction on Globally Accurate Potential Energy Surface

The H+CH_(3) OH reaction,which plays an important role in combustion and the interstellar medium,presents a prototypical system with multiple channels.In this work,mode specific dynamics of different product channels is investigated theoretically on a recently developed reliable potential energy surface based on a large number of data points calculated at the level of UCCSD(T)-F12 a/AVTZ.It has been demonstrated that vibrational excitations of the O-H stretching motion,the torsional motion,the C-H stretching vibrations,show different infuences on the four product channels,H_(2)+CH_(3) O,H_(2)+CH_(2)OH,H_(2) O+CH_(3),and H+CH_(3) OH.This work is helpful for understanding the mode-specific dynamics and controlling the competition for complicated reactions with multiple product channels.

Mode-Specific Quantum Dynamics Study of OH+H_(2)S→H_(2)O+SH Reaction

The hydrogen abstraction reaction from H_(2)S by OH is of key importance in understanding of the causes of acid rain,air pollution,and climate change.In this work,the reaction OH+H_(2)S→H_(2)O+SH is investigated on a recently developed ab initio-based globally accurate potential energy surface by the time-dependent wave packet approach under a reduceddimensional model.This reaction behaves like a barrier-less reaction at low collision energies and like an activated reaction with a well-defined barrier at high collision energies.Exciting either the symmetric or antisymmetric stretching mode of the molecule H_(2)S enhances the reactivity more than exciting the bending mode,which is rationalized by the coupling strength of each normal mode with the reaction coordinate.In addition,the modespecific rate constant shows a remarkable non-Arrhenius temperature dependence.

Rapidity and Pseudorapidity Distributions of theVarious Hadron-Species Produced in High EnergyNuclear Collisions: A Systematic Approach

With the help of a phenomenological approach outlined in the text in some detail, we have dealt here with the description of the plots on rapidity and pseudorapidity spectra of some hadron-secondaries produced in various nucleus-nucleus interactions at high energies. The agreement between the measured data and the attempted fits are, on the whole, modestly satisfactory excepting a very narrow central region in the vicinity of y = η = 0. At last, hints to how the steps suggested in the main body of the text to proceed with the description of the measured data given in the plots could lead finally to a somewhat systematic methodology have also been made.

The Fundamental Mechanism for the Collision/Pressure Induced Optic Effect

In this work, the fundamental mechanism regarding the collision and pressure induced optic effect is elucidated. Based on the concept of the collision-relaxation/the pressure-release induced optic effect put forth here, a new laser technology may be developed. Furthermore, our work also makes the understanding the photon involved chemical reaction become much clear and rationalized.

Stationary patterns in a discrete bistable reaction-diffusion system:mode analysis

This paper theoretically analyses and studies stationary patterns in diffusively coupled bistable elements. Since these stationary patterns consist of two types of stationary mode structure： kink and pulse, a mode analysis method is proposed to approximate the solutions of these localized basic modes and to analyse their stabilities. Using this method, it reconstructs the whole stationary patterns. The cellular mode structures （kink and pulse） in bistable media fundamentally differ from stationary patterns in monostable media showing spatial periodicity induced by a diffusive Taring bifurcation.

不同点火方式下HMX基PBX炸药反应演化过程的特征分析

在长管强约束条件下对HMX基PBX炸药点火实验进行了数值模拟,分析了点火方式对炸药反应演化规律的影响,获得了弱冲击点火条件下炸药反应演化过程的特征图像。针对黑火药和雷管2种点火方式,分别构建了PBX炸药黑火药点燃和冲击起爆2类实验的唯象模型和数值模拟方法,通过数值模拟获得了钢管内炸药柱反应演化进程的特征图像,柱壳膨胀历程与实验结果符合较好。研究表明,不同点火方式下炸药反应演化进程存在较大差异。如果使用雷管点火,PBX炸药会在几微秒内发生爆轰反应;而使用黑火药点火,PBX炸药会在数毫秒内从缓慢燃烧转化为剧烈爆炸,但随着壳体破裂解体,管内压力骤降,抑制了反应演化向爆轰转变。黑火药点燃条件下整个反应演化过程可以分为4个主要阶段,其中管壁附近炸药柱表面燃烧传播优先于炸药柱中心基体反应,是弱冲击点火反应演化过程的重要特征之一。

基于混沌控制的采摘机器人防碰撞系统设计

针对采摘机器人在作业过程中遇到障碍物导致路径规划出现混沌现象的问题,基于混沌控制对采摘机器人防碰撞系统进行设计,并采用模糊自适应控制算法和滑模变结构控制算法结构的方式对系统进行控制。为了验证防碰撞系统的有效性,对采摘机器人进行了防碰撞和采摘仿真试验,结果表明:采摘机器人在作业过程中可以避开障碍物,按照规划路线到达预设位置,完成果蔬的采摘。

氨氢融合零碳内燃机燃烧过程综述

随着中国“碳达峰”与“碳中和”目标的提出,内燃机低碳化、零碳化势在必行。氨作为零碳燃料和氢的高能量密度载体,是实现碳中和有潜力的替代燃料。研发氨氢燃烧技术,实现氨高效清洁融合燃料零碳大功率内燃机高效近零排放对全球气候治理具有重大意义。该文在分析氨作为未来绿色能源的潜力及其在内燃机中实际应用的基础上,从氨氢内燃机的燃烧模式、氨氢燃料的燃烧化学反应动力学、氨氢燃料供给方式等方面综述了氨氢内燃机的燃烧的最新进展,对比分析了火花点燃/均质压燃/射流引燃3种燃烧模式、氨气道喷射/液氨缸内直喷2种燃料供给方式、主动射流/被动射流2种点火方式,提出并论述了基于氨在线裂解制氢实现基于单一液氨燃料油箱的氨氢融合燃烧,是内燃机实现碳中和的极具潜力的技术路线,指出了氨氢内燃机喷雾、燃烧和氮基排放控制三方面需要解决的关键技术和科学问题。研究表明:氨氢融合内燃机采用微量氢气(小于3%)引燃氨混合气,可以获得稳定燃烧和高热效率,并拓展稀然极限。氨氢融合零碳大功率内燃机作为氨燃料高效可靠的应用载体,在重型车辆、工程机械、远洋船舶、发电等多个领域具备广泛的应用潜力与价值,氨氢内燃机的研发可推动基础燃烧理论的进步,也可以促进中国内燃机产业迈上新的台阶。