High-pressure phonon dispersion of copper by using the modified analytic embedded atom method

By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three high symmetry directions and four oft-symmetry directions, and then simulate the phonon dispersion curves of Cu at high pressures of 50, 100, and 150 GPa. The results show that the shapes of dispersion curves at high pressures are very similar to that at zero pressure. All the vibration frequencies of Cu in all vibration branches at high pressures are larger than the results at zero pressure, and increase correspondingly as pressure reaches 50, 100, and 150 GPa sequentially. Moreover, on the basis of phonon dispersion, we calculate the values of specific heat of Cu at different pressures. The prediction of thermodynamic quantities lays a significant foundation for guiding and judging experiments of thermodynamic properties of solids under high pressures.

AN EMBEDDED BOUNDARY METHOD FOR ELLIPTIC AND PARABOLIC PROBLEMS WITH INTERFACES AND APPLICATION TO MULTI-MATERIAL SYSTEMS WITH PHASE TRANSITIONS

The embedded boundary method for solving elliptic and parabolic problems in geometrically complex domains using Cartesian meshes by Johansen and Colella （1998, J. Comput. Phys. 147, 60） has been extended for elliptic and parabolic problems with interior boundaries or interfaces of discontinuities of material properties or solutions. Second order accuracy is achieved in space and time for both stationary and moving interface problems. The method is conservative for elliptic and parabolic problems with fixed interfaces. Based on this method, a front tracking algorithm for the Stefan problem has been developed. The accuracy of the method is measured through comparison with exact solution to a two-dimensional Stefan problem. The algorithm has been used for the study of melting and solidification problems.

FORMATION ENTHALPIES FOR FCC METAL BASED BINARY ALLOYS BY EMBEDDED ATOM METHOD

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Chen’s lattice inversion embedded-atom method for Ni-Al alloy

The structural properties, the enthalpies of formation, and the mechanical properties of some Ni-Al intermetallic compounds （NiAl, Ni3Al, NiAl3, Ni5Al3, Ni3Al4） are studied by using Chen＇s lattice inversion embedded-atom method （CLI-EAM）. Our calculated lattice parameters and cohesive energies of Ni-A1 compounds are consistent with the experimental and the other EAM results. The results of enthalpy of formation indicate a strong chemical interaction between Ni and Al in the intermetallic compounds. Through analyzing the alloy elastic constants, we find that all the Ni-Al intermetallic compounds discussed are mechanically stable. The bulk moduli of the compounds increase with the increasing Ni concentration. Our results also suggest that NiAl, Ni3Al, NiAl3, and Ni5Al3 are ductile materials with lower ratios of shear modulus to bulk modulus; while Ni3Al4 is brittle with a higher ratio.

Structural defects in L1_0 FePt by modified analytic embedded-atom method

The structural defects of L10 FePt are investigated by the molecular dynamics (MD) with a modified analytic embedded-atom method (MAEAM). The L10 ordered structure of FePt is relaxed from a trial fcc structure. The defect formation energies are calculated. The vacancy formation energies of Fe and Pt are 1.89 eV and 2.11 eV respectively. The antisite formation energy of Fe in Pt sublattice is 0.35 eV. The antisite formation energy of Pt in Fe sublattice is 0.09 eV. The tendency of the vacancy formation energy is in agreement with other calculation. The point defect structure types are Pt antisite in rich-Pt side and Fe antisite in rich-Fe side.

The ternary Ni–Al–Co embedded-atom-method potential for γ/γ Ni-based single-crystal superalloys: Construction and application

An Ni-AI-Co system embedded-atom-method potential is constructed for the γ（Ni）/γ＇（Ni3A1） superalloy based on experiments and first-principles calculations. The stacking fault energies （SFEs） of the Ni（Co, A1） random solid solutions are calculated as a function of the concentrations of Co and A1. The calculated SFEs decrease with increasing concentrations of Co and A1, which is consistent with the experimental results. The embedding energy term in the present potential has an important influence on the SFEs of the random solid solutions. The cross-slip processes of a screw dislocation in homogenous Ni（Co） solid solutions are simulated using the present potential and the nudged elastic band method. The cross-slip activation energies increase with increasing Co concentration, which implies that the creep resistance of γ（Ni） may be improved by the addition of Co.

The Embedding Method for Nonsmooth Equations

In this paper. we present a class of' embedding methods for nonsmooth equations. Under suitable conditions, we Prove that there exists a homotopy solution curve, which is Unique and continuous. We also prove that the solution curve is singlcvalue-d with respect to the homotopy parameter. Then we construct all efficient algorithm for this class of equations and prove its convcrgcnce. Filially, we apply the algorithm to the nonlinear complementarity problem. The numerical results show that tile algorithm is satisfacotry.

A Numerical Embedding Method for Solving the Nonlinear Optimization Problem

A numerical embedding method was proposed for solving the nonlinear optimization problem. By using the nonsmooth theory, the existence and the continuation of the following path for the corresponding homotopy equations were proved. Therefore the basic theory for the algorithm of the numerical embedding method for solving the non-linear optimization problem was established. Based on the theoretical results, a numerical embedding algorithm was designed for solving the nonlinear optimization problem, and prove its convergence carefully. Numerical experiments show that the algorithm is effective.

Real-time embedded software testing method based on extended finite state machine

The reliability of real-time embedded software directly determines the reliability of the whole real-time embedded sys- tem, and the effective software testing is an important way to ensure software quality and reliability. Based on the analysis of the characteristics of real-time embedded software, the formal method is introduced into the real-time embedded software testing field and the real-time extended finite state machine （RT-EFSM） model is studied firstly. Then, the time zone division method of real-time embedded system is presented and the definition and description methods of time-constrained transition equivalence class （timeCTEC） are presented. Furthermore, the approaches of the testing sequence and test case generation are put forward. Finally, the proposed method is applied to a typical avionics real- time embedded software testing practice and the examples of the timeCTEC, testing sequences and test cases are given. With the analysis of the testing result, the application verification shows that the proposed method can effectively describe the real-time embedded software state transition characteristics and real-time requirements and play the advantages of the formal methods in accuracy, effectiveness and the automation supporting. Combined with the testing platform, the real-time, closed loop and automated simulation testing for real-time embedded software can be realized effectively.

Construction of embedded-atom-method interatomic potentials for alkaline metals (Li,Na,and K) by lattice inversion

The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li,Na,and K.It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials,especially for the prediction of surface energy.The lattice-inversion embedded-atom-method interatomic potentials for Li,Na,and K are successfully constructed by taking the fourth-neighbor atoms into consideration.These angular-independent potentials markedly promote the accuracy of predicted surface energies,which agree well with experimental results.In addition,the predicted structural stability,elastic constants,formation and migration energies of vacancy,and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations,and the equilibrium condition is satisfied.

Simulation of He Behavior in Metals With Embedded Atom Method

The embedded-atom method(EAM)is used to study the behavior of helium in meta-ls.By fitting the measured parameters such as the activation energy and the heat of solution,the EAM potentials of helium in nickel are extracted.Based upon the EAM potentials,thebinding energy and the self-trapping of helium in nickel are investigated with molecular dynam-ics simulation.

基于全纯嵌入法的配电网光伏接纳能力评估方法

针对大规模分布式光伏接入给配电网带来的电压越限风险,提出了一种基于改进全纯嵌入法的光伏接纳能力评估方法。首先,引入离散-聚合方法对时序数据进行处理,利用所生成极端场景集代替原序列进行接纳能力评估;其次,在传统全纯嵌入模型基础上构建了自定义方向模型,进一步推导了满足电压约束的可行域范围,并将节点Sigma轨迹与可行域边界相交作为单次运算下光伏最大接纳容量的判据;然后,利用蒙特卡罗模拟生成相互独立的光伏接入方案,使用所提判据确定各方案下极端场景集对应的接纳容量;最后,统计计算结果,获取光伏接纳容量的累计分布曲线,以此确定电压越限风险下系统的光伏接纳能力。在IEEE 33节点配电网系统上验证了所提方法的有效性和可行性。

主动配电网潮流的全纯嵌入计算方法

配电网潮流计算是进行配电网规划和运行的重要基础。目前,配电网潮流求解方法主要有牛拉(Newton Raphson,NR)法和前推回代(forward backward substitution,FBS)法两大类,但NR法和FBS法在潮流收敛性和计算效率等方面均存在一定的不足。全纯嵌入法(holomorphic embedding method,HEM)是一种求解非线性潮流方程的新方法,它可以有效避免NR法和FBS法在配电网潮流求解过程中出现的上述问题,但现有HEM未充分考虑配电网中各类型分布式电源(distributed generation,DG)和智能软开关(soft open point,SOP)控制方式的多样性,且未构建计及负荷电压特性和频率特性的潮流模型,难以适用于不同运行模式下配电网潮流计算。针对上述问题,提出一种可求解含多类型DG和SOP且可运行在并网/孤岛模式的主动配电网统一全纯嵌入潮流计算方法。首先,根据负荷静态电压和频率特性,构建计及配电网频率和节点电压影响的负荷节点全纯嵌入潮流模型;其次,根据DG不同的控制方式以及配电网不同的运行模式,将DG所连节点等效为不同节点类型,构建各类DG的全纯嵌入潮流模型;再次,考虑SOP不同控制方式,构建SOP全纯嵌入潮流模型;从次,依据全纯嵌入潮流模型等式左右两侧同次幂级数系数相等原则,推导配电网各全纯函数幂级数系数的求解递推关系式,进而计算各全纯函数的各项幂级数系数,借助解析延拓理论求取电压和频率逼近值,实现配电网潮流的准确求解;最后,通过修改的IEEE-33节点测试系统和IEEE-123节点测试系统验证所提方法准确性和有效性。

多示例学习的簇频繁性分析及双角度融合嵌入

多示例学习(Multi-Instance Learning,MIL)的训练数据是由若干个未带标记的示例组成的带标记的包,基于嵌入的方法,通过将包嵌入成单向量来解决包表示问题,然而大部分现有方法忽略了示例与包的联系,难以保证所选示例的代表性.同时,单角度的嵌入方法无法有效地提取正、负包的差异信息,使嵌入向量的质量较差.提出一种多示例学习的簇频繁性分析及双角度融合嵌入(FADE).簇频繁性分析技术从正、负子空间中分别筛选部分示例作为子空间的簇心,依据簇心将子空间聚类成簇,再计算簇频繁性指标,选择频繁性较高的簇的簇心组成子空间代表示例集.双角度融合嵌入技术基于正、负子空间代表示例集和差值嵌入函数,分别从正、负角度挖掘信息,融合两个角度信息获得最终的嵌入向量.在29个数据集上与七个MIL算法进行了对比实验,结果表明,FADE的分类准确率总体上优于七个对比算法,在图像数据集上有显著优势,在文本和网页数据集上也表现良好.

考虑多失效行为的平衡系统可靠性建模与计算

平衡系统的可靠性建模与相关指标计算是可靠性理论与工程领域的研究热点之一。针对由多部件构成的串联平衡系统,假设每个部件受环境冲击影响逐渐退化,呈现出多种状态;系统的性能平衡取决于部件的状态及其排列位置,即当系统中退化程度超过某一阈值的部件分布在某一特定区域时,系统失去性能平衡。考虑单部件失效导致系统失效和三类系统性能失衡导致系统失效四类失效行为,构建了考虑多失效行为的平衡系统可靠性模型。运用有限马尔可夫链嵌入法推导了部件的相关概率指标以及系统可靠度。最后以液压支架系统为例,验证了所提出模型与方法的有效性。

基于非使用价值评估的绿色基础设施发展模式研究——以南京幕燕森林公园为例

文章预设生态修复和文化开发两种发展模式,采用条件价值问卷对南京幕燕森林公园的非使用价值进行评估,并进行威尔科克森(Wilcoxon)有效性检验与皮尔逊(Pearson)影响因子相关性分析。结果表明:(1)生态修复模式下,2021年幕燕森林公园的非使用价值为4.07亿元,显著高于文化开发模式下的非使用价值总量;(2)实验收集数据不存在嵌入效应,数据具有有效性;(3)受访者的交通便利、文化景观、森林园路状况满意度等自变量与因变量支付意愿(WTP)存在不同程度的显著相关性,而受访者受教育程度、出行时长、交通工具与WTP存在极显著负相关性。最终综合分析实验数据,提出未来幕燕森林公园应遵循的生态修复发展模式以及具体的规划建议。

A Decision Support Framework for the Choice of Languages and Methods for the Design of Real Time Embedded Systems

The choice of methods or design languages is a crucial phase in the development of systems and software, also for real time and embedded systems. An open question that remains in the design of these types of systems is to build a method, or to choose one among those existing, capable to cover the life cycle of a project, and particularly the development phases. This article contributes to answer the question, by proposing an approach based on a multi-criteria comparative study, of few languages and methods dedicated to the design of real time and embedded systems. The underlying objective of this work is to present to designers a wide range of approaches, and elements that can guide their choices. In order to reach this goal, we propose different comparison criteria. Each criterion is divided into sub-criteria, so that the designers can refine their choices according to the qualities they prefer and wish to have in the method or language. We also define a rating scale which is used to assess the retained languages and methods. The scores obtained from this assessment are presented in tables, one table per criterion, followed by a summary table giving the overall scores. Graphics built from these tables are provided and intend to facilitate the judgement and thus the choice of the designers.

A New Method of Embedded Fourth Order with Four Stages to Study Raster CNN Simulation

A new Runge-Kutta （PK） fourth order with four stages embedded method with error control is presentea m this paper for raster simulation in cellular neural network （CNN） environment. Through versatile algorithm, single layer/raster CNN array is implemented by incorporating the proposed technique. Simulation results have been obtained, and comparison has also been carried out to show the efficiency of the proposed numerical integration algorithm. The analytic expressions for local truncation error and global truncation error are derived. It is seen that the RK-embedded root mean square outperforms the RK-embedded Heronian mean and RK-embedded harmonic mean.

面向任务协同的异构多核嵌入式系统实时调度方法

以往的异构多核嵌入式系统实时调度方法由于仅设置了系统实时调度模型的单项参数,导致系统调度时间过长。本文设计了面向任务协同的异构多核嵌入式系统实时调度方法。面向任务协同构建嵌入式系统实时调度模型,计算系统任务节点的传输情况,构建系统实时调度的数学模型,对构建的实时调度模型中的任务数据信息进行汇集,并进行自适应分析处理,以此为基础,设置实时调度模型的时间均衡控制参数和安全性系数,从而实现嵌入式系统的实时调度。通过上述设计,完成对异构多核嵌入式系统实时调度方法的设计。在仿真实验中,与以往的异构多核嵌入式系统实时调度方法相比,本文设计的面向任务协同的异构多核嵌入式系统实时调度方法的调度时间最长仅为5 s,调度时间更短。

嵌入式无线传感器低功耗控制方法设计

常规的嵌入式无线传感器低功耗控制方法主要利用智能拓扑控制算法收集节点功耗反馈信息,易受邻近节点遍历作用影响,导致不同条件下的控制功耗较高。因此,需要设计一种全新的嵌入式无线传感器低功耗控制方法。文章分析了嵌入式无线传感器节点功耗,生成了嵌入式传感器低功耗控制通信协议,设计了无线传感器智能低功耗控制放大器,从而实现了无线传感器低功耗控制。实验结果表明,设计的嵌入式无线传感器低功耗控制方法在不同的控制条件下的控制功耗较低,证明设计的无线传感器低功耗控制方法的效果较好,具有可靠性,为提高嵌入式无线传感器综合性能做出了一定的贡献。