A database and sublattice model for molten salts

A thermodynamic database for molten salt solutions is being developed through the systematic optimization of binary and ternary data. Over 200 systems have been evaluated. Parameters for the subsystems of the Li, Na, K/F, Cl, OH, CO₃, SO₄ system are tabulated. For calculating activities in multicomponent solutions, a sublattice model is used. Equations for integral and partial properties are given in full. For each sublattice it is shown how a consistent “Kohler -Toop” (or “Muggianu-Toop”) formalism can be devised for multi component systems. The practical significance and importance of the various terms in the sublattice model as applied to molten salts are discussed. An example of automatic accessing of the multicomponent salt database for equilibrium calculations with the F1A1C1T system is presented.     

Adaptive Executions of Multi-Physics Coupled Applications on Batch Grids

Long running multi-physics coupled parallel applications have gained prominence in recent years. The high computational requirements and long durations of simulations of these applications necessitate the use of multiple systems of a Grid for execution. In this paper, we have built an adaptive middleware framework for execution of long running multi-physics coupled applications across multiple batch systems of a Grid. Our framework, apart from coordinating the executions of the component jobs of an application on different batch systems, also automatically resubmits the jobs multiple times to the batch queues to continue and sustain long running executions. As the set of active batch systems available for execution changes, our framework performs migration and rescheduling of components using a robust rescheduling decision algorithm. We have used our framework for improving the application throughput of a foremost long running multi-component application for climate modeling, the Community Climate System Model (CCSM). Our real multi-site experiments with CCSM indicate that Grid executions can lead to improved application throughput for climate models.     

Thermodynamic description of the constitutive binaries of the NaCl-KCl-UCl3-PuCl3 system

Thermodynamic assessment of the constitutive binaries of the NaCl-KCl-UCl₃-PuCl₃ system was carried out by CALPHAD (CALculation of PHase Diagrams) approach. The liquid phase was described by the substitutional solution model, and the intermediate compounds were treated as stoichiometric phases. The thermodynamic parameters of the binary systems were obtained based on experimental phase equilibria data available in the literature and theoretical prediction data by first-principles calculations and empirical equations. A set of self-consistent thermodynamic parameters for each of the binary system was finally obtained. Some representative liquidus surface projections, isothermal sections and pseudo-binary phase diagram for the sub-ternary and quaternary systems were calculated by model extrapolation. The influence of KCl on the thermodynamic behavior of NaCl-UCl₃-PuCl₃ matrix salt was analyzed. The extrapolated results indicated that KCl can be used as a candidate additive component of NaCl-UCl₃-PuCl₃ matrix salt from the point of view of thermodynamics. This study provided a comprehensive understanding for the thermodynamic behavior of a candidate molten salt fast reactor nuclear fuel and a fundament for the design of nuclear fuel.     

Modelling and calculation of the phase diagrams of the LiF–NaF–RbF–LaF3 system

Four ternary phase diagrams of the quaternary system LiF–NaF–RbF–LaF₃ were calculated from the data of LiF–NaF, LiF–RbF, LiF–LaF₃, NaF–RbF, NaF–LaF₃ and RbF–LaF₃ binary phase diagrams using the Kohler symmetric and Kohler–Toop asymmetric approximation. Excess Gibbs parameters of all six mentioned binaries were optimized using the experimental results taken from the literature. For the LiF–RbF system our own data were used. In all cases very good agreement between the experimental data and our optimized values was achieved. Excess Gibbs functions for the liquid phases were obtained using the modified quasi-chemical method based on quadruplet interactions and the excess Gibbs function for the solid solution was calculated by a sublattice model. The quaternary eutectic was determined and a set of pseudo-ternary systems with fixed ratio of LaF₃ was calculated in order to find the optimal composition for a molten salt fuel.     

时滞和扩散驱动下信息物理融合系统恶意病毒传播动力学

本文提出了信息物理融合系统(CPS)中具有反应扩散效应的时滞恶意病毒传播模型, 研究了恶意病毒传播 的空间格局动态演化机制, 为恶意病毒在信息物理融合系统中预测和控制提供了战略指导. 给出了模型的基本再 生产数, 并分析了空间中无病毒平衡点和地方病毒平衡点的存在性. 在无时滞条件下建立了扩散引发的图灵不稳 定条件; 在有时滞条件下得到了时滞依赖的稳定性条件和Hopf分岔判据. 最后, 通过数值仿真验证了理论分析的正 确性.     

盐-水-乙醇-乙二醇体系汽液平衡的预测

电解质溶液汽液平衡的预测和计算是是热力学的一个重要研究领域,是加盐萃取精馏模拟计算的重要基础,精 确的推算电解质溶液的汽液平衡数据有着十分重要的理论和实际意义。本文改进了计算电解质溶液汽液平衡的LI- QUAC模型,用计算水-乙醇-乙二醇体系汽液平衡更为精确的NRTL模型代替lIQUAC模型中的UNIFAC模型来计 算溶剂分子间相互作用对超额Gibbs自由能的影响,并据此推算出两种盐-水-乙醇-乙二醇体系的汽液平衡数据, 与本文实验数据及文献数据比较,结果比较满意。该模型对电解质溶液汽液平衡的进一步研究以及加盐萃取精馏的工 程计算均具有一定的指导意义。     

Modelling the effective thermal conductivity of compressing structures including contact resistance

A multi-physics simulation-based methodology for estimating the effective conductivity of single or repeated arrays of mechanically deforming structures being compressed between solid planer surfaces is detailed in this work. The proposed methodology utilises Finite Element (FE) simulations to determine the mechanical environment and resulting shape of the deforming structures together with its effective bulk thermal conductivity by simulating the heat transfer through the structure(s). Importantly, the FE model also incorporates the constriction thermal resistance as well as the contact thermal resistance associated with the contact region between the deforming structure(s) and the rigid planer surfaces. The latter is endemically problematic to predict and an approach is proposed which combines accurate multi-physics simulations with precision experiments to estimate the contact resistance in terms of contact pressure on the deforming structure(s). The thermal-mechanical simulation results are compared with experiments for one exemplar geometry verifying the efficacy of the approach. Although illustrated here for determining the effective thermal conductivity, the method is equally valid for determining effective electrical conductivity of deforming electrically conductive structures undergoing compression between rigid planer surfaces.     

Aircraft design optimization

In this paper we describe briefly a set of procedures for the optimal design of full mission aerospace systems. This involves multi-physics simulations at various fidelity levels, surrogates, distributed computing and multi-objective optimization. Low-fidelity analysis is used to populate a database of inputs and outputs of the system simulation and Neural Networks are then designed to generate inexpensive surrogates. Higher fidelity is used only where is warranted and also to do a local exploration after global optimization techniques have been used on the surrogates in order to provide plausible initial values. The ideas are exemplified on a generic supersonic aircraft configuration, where one of the main goals is to reduce the ground sonic boom.     

混合熔盐物性数据库的设计开发

物性数据及其推算对于化工过程模拟、优化和设计具有重要意义。本文探讨了熔盐用于生物质快速催化热裂解生物质的前景。熔盐的熔点、密度、粘度和表面张力等物性数据对生物质热裂解过程有重要影响。本文针对熔盐快速催化热裂解生物质的特定需求,采用热分析法测定了多种混和熔盐的熔点数据;收集整理了文献中的熔点、密度、粘度和表面张力等熔盐物性数据,对其进行了可靠性等级评定;开发了基于Web的熔盐物性数据库。该数据库具有界面友好、操作方便等优点,利用该数据库,可以查询、修改和补充熔盐物性数据。     

Multiphase Flow in Deforming Porous Media: A Review

In this work we present a general model for the analysis of multiphase flow in deforming porous media with particular regard to concrete and biological tissues. Such problems are typically multi-physics ones with overlapping domains where diffusion, advection, adsorption, phase change, deformation, chemical reactions and other phenomena take place in the porous medium. For the analysis of such a complex system, the model here proposed is obtained from microscopic scale by applying the thermodynamically constrained averaging theory which guarantees the satisfaction of the second law of thermodynamics for all constituents both at micro and macro-level. Furthermore, one can obtain some important thermodynamic restrictions for the evolution equations describing the material deterioration. Two specific forms of the general model adapted to the cases of cementitious and biological materials respectively are shown. Some numerical simulations aimed at proving the validity of the approach adopted, are also presented and discussed.     

Application of geometric models for calculation of viscosity and density of LiNO3 and CsNO3 based ternary nitrate salt systems

Determining the thermophysical properties of ternary molten salt systems accurately is a challenging task as it incorporates experimentation at high temperatures, cost of running the experiments, and complexity due to material interactions. Modelling of these properties can overcome most of these difficulties. In this paper, various geometric models were used for determining the density and viscosity of two ternary nitrate salt systems viz. LiNO₃–NaNO₃–KNO₃ and CsNO₃–NaNO₃–KNO₃. On comparison, it was observed that the General Solution Model (GSM) developed by K.C. Chou predicts better results for both density and viscosity of the salts. The density prediction of the salt systems using GSM recorded an error less than 2%, while the prediction of viscosity showed a variation of 17–20%.     

Visualizing multiphysics,fluid-structure interaction phenomena in intracranial aneurysms

This work presents recent advances in visualizing multi-physics, fluid-structure interaction (FSI) phenomena in cerebral aneurysms. Realistic FSI simulations produce very large and complex data sets, yielding the need for parallel data processing and visualization. Here we present our efforts to develop an interactive visualization tool which enables the visualization of such FSI simulation data. Specifically, we present a ParaView–NekTar interface that couples the ParaView visualization engine with NekTar’s parallel libraries, which are employed for the calculation of derived fields in both the fluid and solid domains with spectral accuracy. This interface allows the flexibility of independently choosing the resolution for visualizing both the volume data and the surface data from each of the solid and fluid domains, which significantly facilitates the visualization of complex structures under large deformations. The animation of the fluid and structure data is synchronized in time, while the ParaView–NekTar interface enables the visualization of different fields to be superimposed, e.g. fluid jet and structural stress, to better understand the interactions in this multi-physics environment. Such visualizations are key towards elucidating important biophysical interactions in health and disease, as well as disseminating the insight gained from our simulations and further engaging the medical community in this effort of bringing computational science to the bedside.     

Inverse and direct magnetic shaping problems

In this work, we study the direct and inverse problems arising from electromagnetic shaping in applications such as continuous casting processes. The magnetic field produces a surface pressure which forces a molten metal to change its shape until it reaches an equilibrium state between the magnetic pressure and the surface tension. The arising direct problem is a free boundary problem which is to determine the shape of molten metals for a given magnetic field. On the other hand, the inverse problem is to seek a configuration of electromagnetic field generators (i.e. inductors) in order that molten metals have prescribed shapes. A level set method will be presented to determine an equilibrium shape formed by a given configuration of magnetic fields. Also a computational method as well as uniqueness results for the inverse problem will be introduced and illustrated with examples.     

Scalability of a multi-physics system for forest fire spread prediction in multi-core platforms

The Journal of Supercomputing - Advances in high-performance computing have led to an improvement in modeling multi-physics systems because of the capacity to solve complex numerical systems in a...     

A preconditioning strategy for microwave susceptibility in ferromagnets

3D numerical simulations of ferromagnetic materials can be compared with experimental results via microwave susceptibility. In this paper, an optimised computation of this microwave susceptibility for large meshes is proposed. The microwave susceptibility is obtained by linearisation of the Landau and Lifchitz equations near equilibrium states and the linear systems to be solved are very ill-conditioned. Solutions are computed using the conjugate gradient method for the normal equation (CGN Method). An efficient preconditioner is developed consisting of a projection and an approximation of an “exact” preconditioner in the set of circulant matrices. Control of the condition number due to the preconditioning and evolution of the singular value decomposition are shown in the results.     

A large scale parallel fluid-structure interaction computing platform for simulating structural responses to a detonation shock

Due to the intrinsic nature of multi-physics, it is prohibitively complex to design and implement a simulation software platform for study of structural responses to a detonation shock. In this article, a partitioned fluid-structure interaction computing platform is designed for parallel simulating structural responses to a detonation shock. The detonation and wave propagation are modeled in an open-source multi-component solver based on OpenFOAM and blastFoam, and the structural responses are simulated through the finite element library deal.II. To capture the interaction dynamics between the fluid and the structure, both solvers are adapted to preCICE. For improving the parallel performance of the computing platform, the inter-solver data is exchanged by peer-to-peer communications and the intermediate server in conventional multi-physics software is eliminated. Furthermore, the coupled solver with detonation support has been deployed on a computing cluster after considering the distributed data storage and load-balancing between solvers. The 3D numerical result of structural responses to a detonation shock is presented and analyzed. On 256 processor cores, the speedup ratio of the simulations for a detonation shock reach 178.0 with 5.1 million of mesh cells and the parallel efficiency achieve 69.5%. The results demonstrate good potential of massively parallel simulations. Overall, a general-purpose fluid-structure interaction software platform with detonation support is proposed by integrating open source codes. And this work has important practical significance for engineering application in fields of construction blasting, mining, and so forth.     

WSA制酸工艺主要过程控制系统设计与开发

WSA制酸工艺中熔盐系统温度控制直接影响到SO2→SO3的转化率和烟气净化效果。本文在简介了WSA制酸工艺、DeltaV系统之后重点描述了熔盐温度、烧嘴燃烧、风机控制与系统连锁等控制流程设计、策略与实现方法以及软件设计的情况。     

A mathematical formulation of uncertain information

This paper introduces a mathematical model of uncertain information. Each body of uncertain information is an information quadruplet, consisting of a code space, a message space, an interpretation function, and an evidence space. Each information quadruplet contains prior information as well as possible new evidence which may appear later. The definitions of basic probability and belief function are based on the prior information. Given new evidence, Bayes' rule is used to update the prior information. This paper also introduces an idea of independent information and its combination. A combination formula is derived for combining independent information. Both the conventional Bayesian approach and Dempster-Shafer's approach belong to this mathematical model. A Bayesian prior probability measure is the prior information of a special information quadruplet; Bayesian conditioning is the combination of special independent information. A Dempster's belief function is the belief function of a different information quadruplet; the Dempster combination rule is the combination rule of independent quadruplets. This paper is a mathematical study of handling uncertainty and shows that both the conventional Bayesian approach and Dempster-Shafer's approach originate from the same mathematical theory.This work was supported in part by the National Science Foundation under grant number IRI-8505735 and a summer research grant of Ball State University.