There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Lithium (Li)-ion batteries (LIB) have governed the current worldwide rechargeable battery market due to their outstanding energy and power capability. In particular, the LIB's role in enabling electric vehicles (EVs) has been highlighted to replace the current oil-driven vehicles in order to reduce the usage of oil resources and generation of CO2 gases. Unlike Li, sodium is one of the more abundant elements on Earth and exhibits similar chemical properties to Li, indicating that Na chemistry could be applied to a similar battery system. In the 1970s-80s, both Na-ion and Li-ion electrodes were investigated, but the higher energy density of Li-ion cells made them more applicable to small, portable electronic devices, and research efforts for rechargeable batteries have been mainly concentrated on LIB since then. Recently, research interest in Na-ion batteries (NIB) has been resurrected, driven by new applications with requirements different from those in portable electronics, and to address the concern on Li abundance. In this article, both negative and positive electrode materials in NIB are briefly reviewed. While the voltage is generally lower and the volume change upon Na removal or insertion is larger for Na-intercalation electrodes, compared to their Li equivalents, the power capability can vary depending on the crystal structures. It is concluded that cost-effective NIB can partially replace LIB, but requires further investigation and improvement.

/pdf/electrode-materials-for-rechargeable-sodium-ion-batteries-1cf2yiiw7z.pdf

Electrode Materials for Rechargeable Sodium-Ion Batteries: Potential Alternatives to Current Lithium-Ion Batteries

Preface IONIC MEMORY TECHNOLOGY Introduction Ionic Memory Switching Mechanisms Materials for Ionic Memories Electrical Characteristics of Ionic Memories Architectures for Ionic Memories Challenges of Ionic Memories Applications of Ionic Memories Summary COMPOSITE SOLID ELECTROLYTES Introduction Interface Interactions and Defect Equilibria in Composite Electrolytes Nanocomposite Solid Electrolytes: Grain Size Effects Ionic Transport Other Properties Computer Simulations Design of the Composite Solid Electrolytes: General Approaches and Perspectives Composite Materials Operating at Elevated Temperatures Conclusions ADVANCES IN THE THEOETICAL DESCRIPTION OF SOLID-ELECTROLYTE SOLUTION INTERFACES Introduction Theoretical Approaches Computer Simulations DYNAMICAL INSTABILITIES IN ELECTROCHEMICAL PROCESSES Introduction Origin and Classification of Dynamical Instabilities in Electrochemical Systems Methodology Dynamics Control of Dynamics Toward Applications Summary and Outlook FUEL CELLS: ADVANCES AND CHALLENGES Introduction Alkaline and Alkaline Membrane Fuel Cells Polymer Electrolyte Membrane Fuel Cells Phosphoric Acid Fuel Cells and Molten Carbonate Fuel Cells Solid Oxide Fuel Cells Emerging Fuel Cells Applications of Fuel Cells Final Remarks ELECTRODES FOR HIGH-TEMPERATURE ELECTROCHEMICAL CELLS: NOVEL MATERIALS AND RECENT TRENDS Introduction General Comments Novel Cathode Materials for Solid Oxide Fuel Cells: Selected Trends and Compositions Oxide and Cermet SOFC Anodes: Relevant Trends Other Fuel Cell Concepts: Single-Chamber, Micro-, and Symmetrical SOFCs Alternative Fuels: Direct Hydrocarbon and Direct Carbon SOFCs Electrode Materials for High-Temperature Fuel Cells with Proton-Conducting Electrolytes Electrolyzers, Reactors, and Other Applications Based on Oxygen Ion- and Proton-Conducting Solid Electrolytes Concluding Remarks ADVANCES IN FABRICATION, CHARACTERIZATION, TESTING, AND DIAGNOSIS OF HIGH-PERFORMANCE ELECTRODES FOR PEM FUEL CELLS Introduction Advanced Fabrication Methods for High-Performance Electrodes Characterization of PEM Fuel Cell Electrodes Testing and Diagnosis of PEM Fuel Cell Electrodes Final Comments NANOSTRUCTURED ELECTRODES FOR LITHIUM ION BATTERIES Introduction Positive Electrodes: Nanoparticles, Nanoarchitectures, and Coatings Negative Electrodes Concluding Remarks MATERIALS SCIENCE ASPECTS RELEVANT FOR HIGH-TEMPERATURE ELECTROCHEMISTRY Introduction Powder Preparation, Forming Processes, and Sintering Phenomena Cation Diffusion Thermomechanical Stability Thermodynamic Stability of Materials OXYGEN- AND HYDROGEN-PERMEABLE DENSE CERAMIC MEMBRANES Introduction Structure of Membrane Materials Synthesis and Permeation Experimental Methods Gas Permeation Models Characteristics of Oxygen-Permeable Membranes Characteristics of Hydrogen-Permeable Membranes Applications of Membranes Summary and Conclusions INTERFACIAL PHENOMENA IN MIXED CONDUCTING MEMBRANES: SURFACE OXYGEN EXCHANGE- AND MICROSTRUCTURE-RELATED FACTORS Introduction Surface Exchange Microstructural Effects in Mixed Conducting Membranes Thermodynamic and Kinetic Stability

Electrodes, interfaces and ceramic membranes

The effect of the radius of the alkali-earth cation substituted into the A sublattice of La0.5A0.5Mn0.5Ti0.5O3–δ (А = Са, Sr, Ba) perovskites on their stability and transport and thermomechanical properties is considered. The increase in the cation radius is shown to improve the phase stability and decrease the conductivity under both oxidative and reductive conditions. The thermal and chemical expansion of La0.5A0.5Mn0.5Ti0.5O3–δ ceramics is studied by dilatometry in controlled atmospheres and a wide temperature range at p(O2)=10–21–0.21 atm. The coefficients of thermal expansion of La0.5A0.5Mn0.5Ti0.5O3–δ are in the interval of (10.7–14.3)× 10–6 K–1, i.e., compatible with those of standard solid electrolytes of solid-oxide fuel cells. The maximum chemical expansion does not exceed 0.2% at isothermal reduction in the CO‒CO2 mixture.

Electrophysical and thermomechanical properties of perovskites La 0.5 A 0.5 Mn 0.5 Ti 0.5 O 3–δ (A = Ca, Sr, Ba) used as fuel cell anodes: the effect of radius of alkali-earth cation

Research on the Electrochemistry of Oxygen Ion Conductors in the Former Soviet Union. Part 2. Perovskite-Related Oxides

Polycrystalline Bi 2-x La x V 0.90 Cu 0.10 O 5.5-δ (x = 0, 0.10 and 0.20) and Bi 1.90 Pr 0.10 V 0.90 Cu 0.10 O 5.5-δ were prepared by the standard ceramic-synthesis technique. The total electrical conductivity of Bi 1.90 La 0.10 V 0.90 Cu 0.10 O 5.5-δ at temperatures above 500 K is slightly lower than undoped BICUVOX.10, but transport properties in the temperature range 370 - 450 K are similar. Doping BICUVOX.10 with praseodymium led to the formation of impurity phases, and to both lower conductivity and thermal expansion of ceramic samples. Oxygen-ion transference numbers of phases with moderate rare-earth dopant content (x ≤ 0.10) vary in the range 0.90 - 0.99 at 780 - 910 K and decrease with increasing temperature. Thermal expansion coefficients calculated from the dilatometric data for Bi 2-x Ln x V 0.90 Cu 0.10 O 5.5-δ ceramics are (16.1 - 18.0) × 10 -6 K -1 at 730 - 1050 K.

/pdf/propiedades-de-transporte-de-ceramicas-bicuvox-dopadas-2bakon79pl.pdf

Vladislav V. Kharton

Papers

Electrodes, interfaces and ceramic membranes

Electrophysical and thermomechanical properties of perovskites La 0.5 A 0.5 Mn 0.5 Ti 0.5 O 3–δ (A = Ca, Sr, Ba) used as fuel cell anodes: the effect of radius of alkali-earth cation

Research on the Electrochemistry of Oxygen Ion Conductors in the Former Soviet Union. Part 2. Perovskite-Related Oxides

Propiedades de transporte de ceramicas Bicuvox dopadas

Physico-Chemical Properties of SrCo1-xFexO3-δ Conductors.