从美国EMPIRE软件看大型高功率脉冲电磁等离子体程序研发趋势

EMPIRE软件是美国针对下一代高性能计算平台开发的电磁等离子体模拟软件,可用于高置信度地开展高功率脉冲产生、传输以及与物质互作用的全过程模拟。解读EMPIRE软件的研制进展对发展大型高功率脉冲电磁等离子体软件具有重要借鉴意义。首先分析了EMPIRE软件的架构及数学物理方案,然后着重讨论了其性能可移植性的软件特征和各子模块的算法特点,最后结合具体的应用案例展示了EMPIRE的强大计算能力。解读EMPIRE的启示包括如下几点:使用异构架构是实现未来E级(百亿亿次级)计算能力部署的关键点;研制灵活的功能模块,开展分层级的建模计算,最后拉通整个物理过程链条模拟,能够有效发挥装置指标的数值评估作用;多团队协作共同开发是丰富软件功能的基础;软件的置信度需要全方位的验证与确认。

EMPIRE计算30MeV以下^(238)U中子核反应数据

为进一步完善核数据评价手段,本文将EMPIRE应用到中子引起锕系核素的核反应模型分析中,根据中子核反应机制的特点,选取恰当的核反应模型及模型参数,以实验数据为基础对模型参数进行调整,由EMPIRE计算获得30 MeV以下能区n+238 U的核反应数据。从计算结果与实验数据以及各评价库数据对比来看,EMPIRE可得到较合理的结果。

“MB”首冠!iG击败Empire获MAS总冠军

3月22日,Major All Stars总决赛在马来西亚首度吉隆坡落下帷幕,代表中国参赛的iG收获了最终冠军。值得一提的是,这也是B神加盟iG以来收获的首个线下赛冠军!MB组合线下首秀参加本次MAS总决赛的共有8支队伍,除了iG之外,还有Na’Vi、Empire、Rave等世界一线队伍。在这些参赛队中,Na’Vi和Empire无疑是iG的最大对手。

Study on Coercive Force of Metallic Cobalt Powder

The experimental regularity and the mechanism of coercive force of metallic cobalt powders and WC Co mixture powders used for WC Co cemented carbides production were explored. The results show that the specific coercive force H sc is a practical physical parameter which can show exactly the demagnetization characteristic of cobalt, and its magnitude is related to structure of cobalt. The H sc of WC Co mixture powders bears a simple positive going relation to Co content in them when the structure of cobalt is constant. It increases with fining and well distributing of cobalt particles in WC Co mixture powders due to the increase of the magnetic moment interaction of adjacent cobalt particles and the residual stress existing among powder particles by grinding.

Coercive Force of γ-Phase in WC-Co Cemented Carbides

The influence of γ-phase composition in WC-Co cemented carbides on its specific coercive force H_(sc) hasbeen studied by analysing the imitative alloys of γ-phase. The results show that the H_(sc) of γ-phase is lower thanthat of pure cobalt, because the solute W can raise γ-phase H_(sc) but the carbon exhibits more intense negativeeffect on H_(sc). The effect is enhanced with raising the C solubilities in γ-phase.

High Coercive NdFeB Thin Film Obtained by Diffusion Annealing

The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0～3.3), then diffused and crystallized by annealing at 650℃ for 10 min. The film without Nd layer showed soft magnetic behavior and high content of a-Fe phase. The films with R > =1 showed good hard magnetic properties with the high coercivity of about 20 kOe.

A NOVEL ROUTE FOR MAKING COERCIVE NdFeB POWDER——HDD PROCESS

NdFeB coercive powder can be obtained directely by hydrogen treated ahoy ingots, The magnetic properties of the powder are comparable with that made by rapidsolidified process.An appreciable coercivity created during hydrogen treatment is closely related to the refined crystal grains.

Improvement of Coercive Force of(CoFe)_3O_4 by Doping Ce

Ce_x(CoFe)_(3-x)O_4 ferrites with different contents of Ce have been prepared by wetchemical method. The phases, morphologies and magnetic properties of the products were studied.It has been found that the products were a single phase with spinel structure and consisted of granular particles in most cases.The coercive force of the products increased with the increase of concentration of Ce￣(4+) in the reaction solution.On the other hand,if Ce￣(3+) and Ce(OH)_4 were present in the reaction solution,some rod-shape crystals in the products were observed, which causes a great increase in coercive force,and the optimum value was obtained when[Ce￣(3+)] was about 5% of the total([Ce￣(3+)]+[Ce￣(4+)]).

Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models

Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging issue.In this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,30°,45°,60°,and 90°),under multiple levels of direct shearing for the first time.The results show that the anisotropic creep of shale exhibits a significant stress-dependent behavior.Under a low shear stress,the creep compliance of shale increases linearly with the logarithm of time at all bedding orientations,and the increase depends on the bedding orientation and creep time.Under high shear stress conditions,the creep compliance of shale is minimal when the bedding orientation is 0°,and the steady-creep rate of shale increases significantly with increasing bedding orientations of 30°,45°,60°,and 90°.The stress-strain values corresponding to the inception of the accelerated creep stage show an increasing and then decreasing trend with the bedding orientation.A semilogarithmic model that could reflect the stress dependence of the steady-creep rate while considering the hardening and damage process is proposed.The model minimizes the deviation of the calculated steady-state creep rate from the observed value and reveals the behavior of the bedding orientation's influence on the steady-creep rate.The applicability of the five classical empirical creep models is quantitatively evaluated.It shows that the logarithmic model can well explain the experimental creep strain and creep rate,and it can accurately predict long-term shear creep deformation.Based on an improved logarithmic model,the variations in creep parameters with shear stress and bedding orientations are discussed.With abovementioned findings,a mathematical method for constructing an anisotropic shear creep model of shale is proposed,which can characterize the nonlinear dependence of the anisotropic shear creep behavior of shale on the bedding orientation.

Coercive Force and Antimagnetizing Mechanism Relating to Size of Ferromagnetic Microcrystal--A Consummating to Result of Stoner-Wohlforth Theory

The expression of critical size of ferromagnetic microcrystal in an external magnetic field with an intensity of H is derived by means of comparing energies of domain structure states.The ferromagnetic microcrystal here means an ferromagnetic single crystal with the size which is smaller than L0, and L0 is the critical value of the size of single-domain particles at the external magnetic field intensity H =0.Also, the coercive strength H(Ls) relating to the size of microcrystal Ls is given and quantitatively evaluated with the material SmCo5 as an instance.It is thus concluded that if L0 ＞ Ls ＞ LC, the antimagnetization of microcrystal will be subjected to a multi-domain process just like the particles of a size greater than L0, only if Ls ＜ LC, the anti-magnetizaton will be carried on in accordance with the Stoner-Wohlforth mechanism( LC is the maximum size of microcrystal with MHcth ).It is suggested that the material RECo5 is available to make an advanced magnet with MHC = 2 K/Mc.

The Importance of Food Security from the Perspective of Food Issue of the Roman Empire

This paper firstly introduced characteristics of the food production( or grain production) and regulation of the prosperous period of the Roman Empire. Then,it discussed the shortcomings and summarized the experience and lessons. It is expected to provide some references for construction of China's food security.

A General Projection Method for a System of Relaxed Coercive Variational Inequalities in Hilbert Spaces

In this paper,we consider a new algorithm for a generalized system for relaxed coercive nonlinear inequalities involving three different operators in Hilbert spaces by the convergence of projection methods.Our results include the previous results as special cases extend and improve the main results obtained by many others.

History dynamics of unified empire in China(770 BC to 476 BC)

The laws and regulations in human history can be revealed by computational models.From 221 before Christ(BC)to 1912 Anno Domini(AD),the unification pattern has dominated the main part of Chinese history for 2132 years.Before the emergence of the first unified empire,the Qin Empire in 221 BC,there existed the Eastern Zhou dynasty(770 BC to 221 BC).This long dynasty has two stages,and here we focus on the first stage.This Spring-Autumn stage was from 770 BC(with 148 states)to 476 BC(with 32 states).The whole country(China)is modelled as a multi‐agent system,which contains multiple local states.They behave autonomously under certain action rules(wars and conflicts),which forms the main reason for the annexations and disappearance of most states.Key factors(power,loyalty,bellicosity and alliance)have been considered in our model settings,and simulation outcomes will be monitored and collected.Eventually,an optimal solution is obtained,which well unveils the internal mechanism and statistical features of real big history.Furthermore,counterfactuals are used to explore the non‐linear effects of the key factors,which deepens the authors’understanding of civilisa-tion evolutions in human history.

Incorporating empirical knowledge into data-driven variable selection for quantitative analysis of coal ash content by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS)has become a widely used atomic spectroscopic technique for rapid coal analysis.However,the vast amount of spectral information in LIBS contains signal uncertainty,which can affect its quantification performance.In this work,we propose a hybrid variable selection method to improve the performance of LIBS quantification.Important variables are first identified using Pearson's correlation coefficient,mutual information,least absolute shrinkage and selection operator(LASSO)and random forest,and then filtered and combined with empirical variables related to fingerprint elements of coal ash content.Subsequently,these variables are fed into a partial least squares regression(PLSR).Additionally,in some models,certain variables unrelated to ash content are removed manually to study the impact of variable deselection on model performance.The proposed hybrid strategy was tested on three LIBS datasets for quantitative analysis of coal ash content and compared with the corresponding data-driven baseline method.It is significantly better than the variable selection only method based on empirical knowledge and in most cases outperforms the baseline method.The results showed that on all three datasets the hybrid strategy for variable selection combining empirical knowledge and data-driven algorithms achieved the lowest root mean square error of prediction(RMSEP)values of 1.605,3.478 and 1.647,respectively,which were significantly lower than those obtained from multiple linear regression using only 12 empirical variables,which are 1.959,3.718 and 2.181,respectively.The LASSO-PLSR model with empirical support and 20 selected variables exhibited a significantly improved performance after variable deselection,with RMSEP values dropping from 1.635,3.962 and 1.647 to 1.483,3.086 and 1.567,respectively.Such results demonstrate that using empirical knowledge as a support for datadriven variable selection can be a viable approach to improve the accuracy and reliability of LIBS quantification.

Book Review of The Medical Empire in 20th Century American Literature

As a book review of Medicine Empire in American Literature of the 20th Century by Jiang Tianping’s team, thispaper provides an examination of the developing process of the western medicine’s interaction with the imperialpolitics in the 20th century. It points out that the book has made a great contribution to the interdisciplinary research,medical research, especially western colonialism research.

From Regional to Intercontinental Trade： The Successive European Trade Empires From the 16th to the 18thCentury in Asia

For a very long time, the areas available for continuous long-distance trade were limited to territories of Braudel＇s Mediterrande （1949）. Whatever the commercial organizations （merchants in the Roman or the Fatimid Empires, the Hanseatic League, the Florentine Companies） were, their trade was not able to directly handle branches more than a month＇s sailing from their main base （in the best conditions）. During the three centuries after Vasco de Gama had reached India, European trading areas dramatically expanded to the shores of Asia, and a long period of harsh competition set the East India Companies of the main European powers of the time against one another. What were the elements that allowed these companies to maintain transactions over such vast areas？ And why were some of these companies far more successful than the others？ A large set of secondary sources focusing on one company or on a particular aspect of trade （Chauduri, 1978; Israel, 1989; Subrahmanyan, 1993; Ames, 1996） exist, however, none of them treat their successive successes and failures. The aim of this paper is to briefly review these sources, to extract information from them and to compare the economic adaptations and innovations that allowed these companies to be the greatest of their time.

Phase structure evolution and coercivity mechanism of high-Co containing permanent magnets

The phase structure and magnetic properties of high-Co containing permanent magnets with high thermal stability have been systematically studied in this work.It is abnormal that the coercivity of annealed samples was slightly lower than that of sintered samples,while the coercivity was usually enhanced after annealing in conventional Nd–Fe–B samples.Further analysis showed that in addition to RE2(Fe,Co)14B main phase and RE-rich grain boundary phase,there were also new Co-rich magnetic phases located in the grain boundary.During annealing,the phase structures of high-Co containing magnets were readjusted,especially the increasing Co-rich magnetic phase and emerging RE-rich particles precipitated from the main phase.Eventually,the isolated RE-rich particles would act as the pinning center of the domain wall movement in demagnetization process.It was confirmed that the coercivity of annealed high-Co containing magnets was controlled by both nucleation and pinning.Pinning mechanism can partially compensate for the weakening of magnetic isolation due to increased Co-rich magnetic phase,which explained the moderate decrease in coercivity of annealed high-Co containing magnets.The discovery of new coercivity mechanism contributed to in-depth understanding of high-Co containing magnets.

Coercivity mechanism of La-Nd-Fe-B films with Y spacer layer

The effect of the Y spacer layer on the phase composition,coercivity,and magnetization reversal processes of La-Nd-Fe-B films has been investigated.The addition of a 10 nm Y spacer layer increases the coercivity of the film to 1.36 T at 300 K and remains 0.938 T at 380 K.As the thickness of the Y spacer layer increases,Y participates in the formation of the main phase in the film,and further regulates the formation of La-B phases.The results of the first-order reversal curve(FORC)and micromagnetic fitting show that the coercivity of all the films is dominated by nucleation mechanism.The c-axis preferred orientation,good magnetic microstructure parameters and the largest dipole interaction enhance the coercivity.Therefore,the introduction of the Y spacer layer can be an effective way to improve the coercivity of La-Nd-Fe-B film over a wide temperature range of 150 K-380 K.

Empirical likelihood for spatial cross-sectional data models with matrix exponential spatial specification

In this paper,we study spatial cross-sectional data models in the form of matrix exponential spatial specification(MESS),where MESS appears in both dependent and error terms.The empirical likelihood(EL)ratio statistics are established for the parameters of the MESS model.It is shown that the limiting distributions of EL ratio statistics follow chi-square distributions,which are used to construct the confidence regions of model parameters.Simulation experiments are conducted to compare the performances of confidence regions based on EL method and normal approximation method.