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

Following Chapter 5 where state-of-the-art fuel cell technologies are reviewed, this chapter presents a short survey on the novel electrode materials for the solid oxide fuel cells (SOFCs) with oxygen ion- and proton-conducting electrolytes. Attention is primarily drawn to most recent research studies published during the past few years. Numerous literature data on the electrode performance and key properties of the electrode materials are systematically compared, including the total electrical conductivity, thermal expansion, and reactivity with solid electrolytes. A comparison of the cell performance with various fuels and cell components is also presented. In addition to the fuel cells, related applications such as high-temperature electrolyzers of steam and carbon dioxide are briefly considered.

Electrodes for High-Temperature Electrochemical Cells: Novel Materials and Recent Trends

Oxygen transport in La0.6Sr0.4Mn1-xFexO3 perovskite-like oxides

High-pressure behavior and equations of state of the cobaltates YBaCo 4 O 7 , YBaCo 4 O 7+δ , YBaCoZn 3 O 7 and BaCoO 3-x

a b s t r a c t Effects of iron doping on the functional properties of (La,Sr)CrO3-based electrode materials have been appraised in a range of conditions relevant for SOFCs and other electrochemical applications. Mossbauer spectroscopy of perovskite-type (La0.75Sr0.25)0.95Cr1−xFexO3−i (x = 0.3-0.4), combined with thermogravimetry and X-ray diffraction, shows that the prevailing oxidation state of iron cations in both oxidizing and reducing atmospheres remains 3+. The redox behavior and transport properties are, therefore, essentially governed by Cr3+/4+ couple, leading to dominant p-type electronic conduction in the oxygen partial pressure range from 0.5 down to 10 −20 atm at 973-1223 K. The total conductivity −1 in CO-CO2 at 350-1370 K. The electrochemical activity of porous (La0.75Sr0.25)0.95Cr0.7Fe0.3O3−i anodes with Ce0.8Gd0.2O2−i interlayers, applied onto LaGaO3-based solid electrolyte, is higher compared to (La0.75Sr0.25)0.95Cr0.5Mn0.5O3−i when no metallic current-collecting lay- ers are used. Increasing iron content lowers the electrode performance in wet H2-containing atmospheres, in correlation with electronic conduction.

Thermomechanical, transport and anodic properties of perovskite-type

The Fe–Ni–O system designed for producing bimetal-containing composite anodes of solid oxide fuel cells (SOFCs) was studied. The solubility of nickel in the structure of spinel (Fe,Ni)3O4 ± δ at atmospheric oxygen pressure is ~1/3. Moderate reduction at 1023 K and p(O2) ≈ 10–20 atm leads to partial decomposition of spinels, forming an electron-conducting phase (Fe,Ni)1–yO and submicron bimetallic Fe–Ni particles on the oxide surface, which have potentially high catalytic activity. The electron conductivity has a thermally activated character and increases substantially during the reduction. In the anode conditions of SOFCs, the electric conductivity reaches 30–100 S/cm, while the thermal expansion coefficients are ~12 × 10–6 K–1, which ensures compatibility with solid electrolytes. At the same time, significant volume changes during the redox cycling (up to ~1% on the linear scale) necessitate the introduction of additional components such as yttria-stabilized zirconia (YSZ). The polarization resistance of the model composite anode of reduced Fe2NiO4 ± δ and YSZ deposited on the YSZ solid electrolyte membrane was ~1.8 Ohm cm2 at 923 K in a 4% H2–Ar–H2O atmosphere.

Vladislav V. Kharton

Papers

Electrodes for High-Temperature Electrochemical Cells: Novel Materials and Recent Trends

Oxygen transport in La0.6Sr0.4Mn1-xFexO3 perovskite-like oxides

High-pressure behavior and equations of state of the cobaltates YBaCo 4 O 7 , YBaCo 4 O 7+δ , YBaCoZn 3 O 7 and BaCoO 3-x

Thermomechanical, transport and anodic properties of perovskite-type

Redox Behavior and Transport Properties of Composites Based on (Fe,Ni)3O4 ± δ for Anodes of Solid Oxide Fuel Cells