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

Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

https://hal.archives-ouvertes.fr/hal-02417326/document

Materials for electrochemical capacitors

Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

When combined with transition metals with partially filled d orbitals, magnetism can be incorporated in two-dimensional materials, which greatly expands the scope for fundamental research and potential applications of these materials. Here, a first-principles study of a new two-dimensional ferromagnet VI₃ has been carried out. The structural symmetry and magnetic and electronic properties of VI₃ in its bulk and single layer forms have been confirmed and predicted, respectively. Its ferromagnetic Curie temperature is predicted to be reduced by half in its monolayer form. In addition, the cation substitution in its monolayer has also been studied, which can significantly tune the magnetism.

Tuning Magnetism in Layered Magnet VI₃: A Theoretical Study

Crystalline Mg2Ni obtained by mechanical alloying

By combining carbon woven fabric with thermoplastics, a thermostamping process was proposed to form composite parts with complex double curvatures in one step and to implement affordable applicatio...

Forming of thermoplastic plain woven carbon composites An experimental investigation

Metal Mesh as a Transparent Omnidirectional Strain Sensor

A regularity for transferring molecular hydrogen to active atomic hydrogen has the potential to unlock some key steps in petrochemical processing and in the synthesis of many compounds. Ni2P, which is regarded as a promising next-generation catalyst to replace noble metals in heterogeneous catalysts, is discussed in this paper. In this study, a potential modification regularity was inferred and proved for enhancing hydrogenation properties. This regularity is “modified elements with relatively high electronegativity will favor an increase in the hydrogenation activity, provided crystal metallic properties are retained”. To obtain this regularity, three steps were followed. First, calculations were performed to infer a potential regularity for enhancing hydrogenation activity. Then, two series of catalysts were designed based on the calculations. Second, temperature-programmed oxidation, thermogravimetry, X-ray diffraction, and temperature-programmed reduction analyses were performed to verify the modifica...

Jun Chen

Papers

Tuning Magnetism in Layered Magnet VI₃: A Theoretical Study

Crystalline Mg2Ni obtained by mechanical alloying

Forming of thermoplastic plain woven carbon composites An experimental investigation

Metal Mesh as a Transparent Omnidirectional Strain Sensor

A Potential Regularity for Enhancing the Hydrogenation Properties of Ni2P