Azimuthal distributions of final-state particles and fragments and transverse structure of emission source in high-energy nucleus-nucleus collisions

The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components Px and Py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.

Particle flux through the Huanghai Sea cold water mass

Settling particulate matter （SPM） was collected by using sediment traps at four stations in a survey section from Qingdao to Cheju-do, across the Huanghai Sea cold water mass （HSCWM）, in August 2002. The sediment traps were planted in three layers： the upper layer of the thermocline （ULT） above the HSCWM, the lower layer of the thermocline （LLT）, and the bottom layer of water column （BL）. To determine the particle flux, the contents of organic carbon （POC）, organic nitrogen （PON）, total carbon （PC）, and total phosphorous （PP） in SPM were analyzed, and two flux models （Ⅰ and Ⅱ） were improved to calculate the resuspension ratio, with an assumption in Model Ⅰ that the vertical flux of SPM in the LLT equals the net vertical flux of SPM in the whole water column. An X value, i.e., the fraction of the resuspension flux originating from the surficial sediments nearby the sampling station, was deduced from Model Ⅰ to estimate the contribution of lateral currents to the total resuspension flux. The results showed that inorganic particles, fecal pellets, and miscellaneous aggregates were the major types of SPM in the HSCWM, and the contents of POC, PON, PC, and PP all decreased with water depth. A great deal of fecal pellets found in the LLT indicates that the main space producing biogenic SPM is the thermocline, and especially the LLT, where the C/N ratio is lower than that in the ULT. The resuspension ratios, 90%-96% among stations, imply strong impact ofresuspension on particle flux in the BL. These values were not significantly different between the two flux models, suggesting that the hypothesis in Model Ⅰ that the flux in the LLT equaling the net flux to the bottom is acceptable for shallow waters with stratification like the HSCWM. The POC export ratio from the HSCWM ranges from 35% to 68%. It benefits from the short sinking distance in shallow water. The upwelling in the HSCWM enhanced the POC flux through the water mass, and the lateral currents provides up to being greater than 50% ofresuspension flux in the BL according to evaluation of the X value.

Measurement of neutron and charged particle fluxes toward earthquake prediction

In this paper, we describe a possible method for predicting the earthquakes, which is based on simultaneous recording of the intensity of fluxes of neutrons and charged particles by detectors, commonly used in nuclear physics. These low-energy particles originate from radioactive nuclear processes in the Earth＇s crust. The variations in the particle flux intensity can be the precursor of the earth- quake. A description is given of an electronic installation that records the fluxes of charged particles in the radial direction, which are a possible response to the accumulated tectonic stresses in the Earth＇s crust. The obtained results showed an increase in the intensity of the fluxes for 10 or more hours before the occurrence of the earthquake. The previous version of the installation was able to indicate for the possibility of an earthquake （Maksudov et al. in Instrum Exp Tech 58：130-131, 2015）, but did not give information about the direction of the epicenter location. In this regard, the installation was modified by adding eight directional detectors. With the upgraded setup, we have received both the predictive signals, and signals determining the directions of the location of the forthcoming earthquake, starting 2-3 days before its origin.

Bursty Behaviour of Turbulent Particle and Energy Fluxes in Edge Plasma of HT-7 Tokamak

High time resolution measurements of the electrostatic fluctuations and the turbulent particle and energy fluxes have been performed with a Langmuir probe array in the edge plasma in HT-7 tokamak. Bursty behaviour was observed in the time resolved turbulent fluxes with positive skewness and large kurtosis. The contribution of the large sporadic bursts to the transport losses were estimated. The analysis shows that the turbulent fluxes have different behaviour in different frequency domains and the probability distribution functions （PDFs） of the particle and energy fluxes present two distinct scaling ranges. All these are essentially consistent with the predictions of the self-organized criticality （SOC） model, though further studies are needed.

Development of High-energy Particle Detectors for Space Exploration

Space environment exploration is a hot topic globally.The scope of space exploration ranges from near-Earth space to the moon,other planets in the solar system,and even the heliosphere and interplanetary space.It is used for various crucial applications,including aerospace technology development,space weather research,understanding the origin and evolution of the universe,searching for extraterrestrial life,and finding human livable places.Although China’s space environment exploration started late,its progress has been rapid.China is gradually narrowing the gap with advanced countries and may eventually lead the world in space research.This article briefly reviews the development history of China’s space environmental detectors.

Effect of Doppler Shifts on Photon and Particle Flux of Beams

Reasons are given for a Doppler shift on the number of observed (sensed) photons in a light beam not just a shift in frequency, also a similar (non-relativistic) effect on the number of observed (sensed) particles (with non-zero rest mass) in a particle beam. Optics texts have neither effect.

On The Hardening of The Spectrum of High-Energy Particles Formed in Heavy-Ion Collisions Considered within The Framework of The Hydrodynamic Approach

The emission of high-energy particles in 16O + 197Au collisions at energy 20 MeV / nucleon is considered within the framework of the time evolution of a hot spot taking into account the hydrodynamic compression and expansion stages. In addition, the evaporation of the particles that are formed in the early (hot) stage of the evolution of the hot spot is included in the calculation of the spectrum. This leads to a hardening of the particle spectrum in its high-energy part, which is in agreement with experimental data.

The Ratio of Particle Flux of the Hydrogen to Carbon on Divertor Configuration in HL-2A Tokamak

Interactions of plasma with the walls lead to particle release by various mechanisms and the amount of impurities in the plasma core limits the performance of the device. It is very important to get the particle fluxes for understanding the releasing mechanisms of impurities. The spectroscopic measurements to determine the impurity influx from localized surfaces in tokamak plasma is described in detail in Ref. Determined the origin of the chromium influxes by this method in ASDEX during ICRF heating were reported in Ref.

Relative roles of resuspended particles and pore water in release of contaminants from sediment

Sediment layers containing contaminants play a significant role in environmental hydrodynamics. Experiments were conducted in order to characterize the relative roles of resuspended particles and pore water under different flow and sediment conditions. A conservative tracer （NaC1） and a reactive tracer （phosphate） were used as contaminants in the bottom sediment in a laboratory flume. The mixing between the overlying water and pore water occurred over a short time while the desorption of contaminants from fine-grained resuspended particles lasted a relatively long time. The effects of resuspended particles and pore water on the variations of release flux and concentration of contaminants in water with time under different hydrodynamic conditions were quantified. The results show that pore water dominated the initial release flux, which could be several orders of magnitude greater than the flux due to molecular diffusion. Flux contribution of desorption from sediment particles in the latter release could be equal to what was seen from pore water in the initial stage.

Study on Separation of Water and Alumina Fine Particles by Cross-Flow Microfiltration

A cross-flow microfiltration process had been developed to separate alumina fine particles from the suspension using a stainless steel membrane tube with a pore size of 10 μm. The influence of cross-flow velocity and trans-membrane pressure on the permeate flux and the solid holdup in permeate had been investigated. It was found that both the permeate flux and the solid holdup in permeate decreased with time. Moreover, the permeate flux increased with an increasing transmembrane pressure but the influence of cross-flow velocity on the permeate flux was quite complex. Both the permeate flux and the solid holdup in permeate in long term filtration had been studied. The operation of cross-flow microfiltration could be carried out stably for 10 hours with the permeate flux values ranging from 520.5 to 936 L/(m^2·h) at rs=1%, while it could continue in 10 hours with the permeate flux values ranging from 226 to 432 L/(m^2·h) at rs=5%. The solid holdup in permeate had been less than 10 mg/L during the whole operating cycle.

Cross-satellite calibration of high-energy electron fluxes measured by FengYun-4A based on Arase observations

We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard FengYun-4A(FY-4A)spanning from April 1,2017,to September 30,2019.By tracing the two-dimensional magnetic positions(L,magnetic local time[MLT])of FY-4A at each time,we compare the datasets of the conjugate electron fluxes over the range of 245–894 keV in 6 energy channels for the satellite pair within different sets of L×MLT.The variations in the electron fluxes observed by FY-4A generally agree with the Arase measurements,and the percentages of the ratios of electron flux conjunctions within a factor of 2 are larger than 50%.Compared with Arase,FY-4A systematically overestimates electron fluxes at all 6 energy channels,with the corresponding calibration factors ranging from 0.67 to 0.81.After the cross-satellite calibration,the electron flux conjunctions between FY-4A and Arase show better agreement,with much smaller normalized root mean square errors.Our results provide a valuable reference for the application of FY-4A high-energy electron datasets to in-depth investigations of the Earth’s radiation belt electron dynamics.

A Phenomenological Model for the Electromagnetic Origin of Mass in Particles, and Its Quantitative Application to the Electron, the Muon, the Proton, and the Neutron

A simple phenomenological model is developed, which indicates the existence of a direct link between the concept of rest mass of a particle and magnetodynamic energies associated to the formation of the particle. The model is based upon the principles of quantization and conservation of flux, well known for their application in superconductivity. The charge of particles is considered as forming vortices of superconducting currents, which we postulate are created by electromagnetic fluctuations from vacuum (or related processes). A new quantization rule gathers the size, the magnetic moment, and the rest mass of the particle and associates these quantities to the integer number of flux quanta that should be stored in the vortices corresponding to each particle. The model is applied to the electron, the muon, the proton, and the neutron. Quantitative consistency with available experimental data for these subatomic particles is obtained.

Analysis of the Energetic Particles Around the Chili Earthquake of M8.8

Based on the IDP data from the French DEMETER satellite,global distribution is shown,which corresponds to three precipitation zones:the aural precipitation zone,the mid-high latitude precipitation zone and the South Atlantic precipitation zone.Then the Chili earthquake with M8.8 which occurred on February 27,2010 is taken as an example.The IDP fluxes from repeat orbits are compared and the results show that there is a clear enhancement on February 26,2010,just one day ahead of the Chili earthquake.In the south zone with L=2.1～2.7,the flux on February 26 is higher than that on previous days.However in the north zone with L=2.1～2.7,there is no clear change during the day but great enhancement during the night,which is close to the time of the earthquake.At the same time,the flux on February 26 near the equator is far lower than that on previous days.

Enhancement of High Energy Electron Fluxes and Variation of Atmospheric Electric Field in the Antarctic Region

High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere,and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well.The High-Energy Electron Flux(HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed together with the data of nearsurface atmospheric vertical electric field measured at the Russian Vostok Station.Three HEEF enhancements are identified and it is shown that when the HEEF increases to a certain level,the local atmospheric vertical electric field near the ground can increase substantially than usual.The response time of the electric field to HEEF enhancement is about 3.7 to 4 days.

Microstructure of in situ Al_3Ti/6351Al composites fabricated with electromagnetic stirring and fluxes

The 6351 wrought aluminum alloy and K2TiF6-CaF2-LiCl components were selected as raw materials to fabricate in situ Al3Ti particulate reinforced aluminum alloy at 720℃via direct melt reaction method with electromagnetic stirring(EMS).CaF2 and LiCl acted as fluxes to lower the reaction temperature of the system.It is shown that the electromagnetic stirring and fluxes accelerate the emulsion process of K2TiF6.Optical microscopy,scanning electron microscopy,transmission electron microscopy and energy dispersive spectrum were utilized to analyze the microstructure and components of composites.Compared to composites fabricated without EMS and fluxes,the sizes of endogenetic Al3Ti are refined from 10-15μm to 2-4μm,which are often accompanied with silicon element.The morphology of Al3Ti or Al3TiSi0.22 exhibits triangle,quadrilateral and other clumpy patterns. Because of the Ca elements from CaF2,the sizes of Mg2Si decrease from 8-10μm to 1-2μm due to the formation of Ca2Si.

THE MONSOON IN THE ARABIAN SEA:IMPLICATIONS FROM RADIOLARIAN FLUXES TO THE DEEP SEA

Evolution of Monsoon climate can be attributed to high altitude topography of the Himalaya—Tibetan Plateau. It is important to decipher the modern Monsoon processes in the Indian Ocean so that we will have a better understanding of global evolution of paleoclimate. An international collaborative effort has been expended since 1986 to collect marine particle fluxes in the Arabian Sea where significant amount of organic carbon is fixed annually. Such high biological productivity is mainly due to monsoonal upwelling that occurs twice a year in the region. The southwest (SW) Monsoon occurs in June to September and the northeastern (NE) Monsoon occurs in November to February with a varying degree depending on the regions. PARFLUX sediment traps were deployed in the bathypelagic zone (2800～3000m) at three locations (Western[16°20′N, 60°30′E], Central[14°31′N, 64°46′E], and Eastern[15°31′N, 68 43′E] Stations) representing different patterns and degrees of the Arabian Sea particle fluxes.

Robust Particle Swarm Optimization Algorithm for Modeling the Effectof Oxides Thermal Properties on AMIG 304L Stainless Steel Welds

There are several advantages to the MIG(Metal Inert Gas)process,which explains its increased use in variouswelding sectors,such as automotive,marine,and construction.A variant of the MIG process,where the sameequipment is employed except for the deposition of a thin layer of flux before the welding operation,is the AMIG(Activated Metal Inert Gas)technique.This study focuses on investigating the impact of physical properties ofindividual metallic oxide fluxes for 304L stainless steel welding joint morphology and to what extent it can helpdetermine a relationship among weld depth penetration,the aspect ratio,and the input physical properties ofthe oxides.Five types of oxides,TiO_(2),SiO_(2),Fe_(2)O_(3),Cr_(2)O_(3),and Mn_(2)O_(3),are tested on butt joint design withoutpreparation of the edges.A robust algorithm based on the particle swarm optimization(PSO)technique is appliedto optimally tune the models’parameters,such as the quadratic error between the actual outputs(depth and aspectratio),and the error estimated by the models’outputs is minimized.The results showed that the proposed PSOmodel is first and foremost robust against uncertainties in measurement devices and modeling errors,and second,that it is capable of accurately representing and quantifying the weld depth penetration and the weld aspect ratioto the oxides’thermal properties.

多尺度粒子调控功能复合膜的数值计算

以聚碳酸酯基体与荧光粉粒子构成的功能复合膜为研究对象,结合实验和蒙特卡洛计算机数值计算方法,研究了荧光粉粒子粒径和含量对复合膜光通量与色温的影响。结果表明:荧光粉粒子含量相同时,随着粒径增大,光通量表现为先升高后降低的趋势,在粒径为4.0μm时均具有最大值,色温则表现为先降低后升高的趋势;荧光粉粒子粒径相同时,粒径为0.8~4.0μm,光通量与含量表现为正相关趋势,粒径为4.0~16.0μm,光通量与含量表现为负相关趋势;最优组合为原始掺杂荧光粉粒子粒径为8.0μm,质量分数为25%,搭配粒径为4.0μm,质量分数为75%,对应的光通量为139.81 lm,色温为4 257 K。

电磁磨粒检测中气泡对铜颗粒信号的影响特性分析

三线圈式电磁磨粒传感器在油液在线监测中应用广泛,而油液中的气泡对铜颗粒的检测极易造成干扰,定量分析气泡在颗粒检测时的影响规律将有助于提高电磁磨粒传感器的检测精度。基于电磁磨粒检测中的磁耦合效应,分别研究了气泡间隙、气泡大小、气泡位置以及气泡数量对铜颗粒检测的影响特性,并以大管径通道(?38 mm)电磁磨粒传感器为对象进行仿真和试验。结果表明,气泡与铜颗粒间隙越大,铜颗粒信号幅值越小,影响范围(0.52~10.31)%;气泡尺寸增大铜颗粒信号幅值也增大,气泡直径为20 mm和25 mm时影响分别是3.07%和5.47%;气泡与铜颗粒中心连线与传感器中心轴线的夹角越大,检测影响越小,影响范围(0.4~5.6)%;气泡数量越多干扰越大,单气泡和双气泡的影响程度分别是5.66%和8.74%。

长石对明弧堆焊合金的组织及耐磨性影响

采用侧向添加活性剂的方法研究了长石含量对复合粉粒和实心焊丝明弧堆焊合金的组织及耐磨性影响。借助高速摄像仪分析电弧形态;通过X射线衍射仪、扫描电镜及其附属电子能谱仪和磨损试验机研究堆焊合金的组织及耐磨性。结果表明:添加含长石活性层的挡块后,电弧扩张,形态由钟罩形改变为半球形,这使电弧覆盖面积增加,堆焊合金的粉粒填充量提高,初生M_(7)C_(3)相先从细条状转变为板条状,耐磨性显著增加,但长石过量后,电弧往外扩展过多,对实心焊丝的预热增强而提高其熔化量,粉粒填充量轻微下降,初生M_(7)C_(3)相减小,耐磨性下降。