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

Additive manufacturing of metallic components – Process, structure and properties

Welding Metallurgy of

Balling phenomena in selective laser melted tungsten

Microstructure of selective laser melted AlSi10Mg alloy

Twinning behavior of a strongly basal textured AZ31 Mg alloy during warm rolling

Effect of tempering temperature on the toughness of 9Cr–3W–3Co martensitic heat resistant steel

The twinning and slip system activities during compression testing at room temperature and 150 °C have been investigated for an AZ31 magnesium alloy. The samples, which were cut from a rolled sheet, were compressed with the compression axis taken at different angles to the sheet normal direction. The electron backscatter diffraction technique in the scanning electron microscope was used to investigate the local texture and microstructure evolution. The plastic deformation of magnesium is controlled by both { 1 0 1 ¯ 2 } ⁡ 〈 1 0 1 ¯ 1 〉 twinning and slip during deformation. Extensive twinning takes place when the sample is loaded perpendicular to the basal plane normals (BPNs). A high work-hardening rate, with very little twinning, is observed for samples loaded parallel to the BPNs. The main features of the stress–strain curves can be explained based on the microstructural and texture data.

Wei Liu

Papers

Balling phenomena in selective laser melted tungsten

Microstructure of selective laser melted AlSi10Mg alloy

Twinning behavior of a strongly basal textured AZ31 Mg alloy during warm rolling

Effect of tempering temperature on the toughness of 9Cr–3W–3Co martensitic heat resistant steel

Microtexture evolution via deformation twinning and slip during compression of magnesium alloy AZ31