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

Amorphous alloys were first developed over 40 years ago and found applications as magnetic core or reinforcement added to other materials. The scope of applications is limited due to the small thickness in the region of only tens of microns. The research effort in the past two decades, mainly pioneered by a Japanese- and a US-group of scientists, has substantially relaxed this size constrain. Some bulk metallic glasses can have tensile strength up to 3000 MPa with good corrosion resistance, reasonable toughness, low internal friction and good processability. Bulk metallic glasses are now being used in consumer electronic industries, sporting goods industries, etc. In this paper, the authors reviewed the recent development of new alloy systems of bulk metallic glasses. The properties and processing technologies relevant to the industrial applications of these alloys are also discussed here. The behaviors of bulk metallic glasses under extreme conditions such as high pressure and low temperature are especially addressed in this review. In order that the scope of applications can be broadened, the understanding of the glass-forming criteria is important for the design of new alloy systems and also the processing techniques.

https://www.tcd.ie/Physics/people/Graham.Cross/SF%20Poster%202011/Shek-MaterSciEng04-Bulk%20Metallic%20Glasses.pdf

Bulk metallic glasses

Bulk metallic glasses (BMGs) have been classified according to the atomic size difference, heat of mixing (� H mix ) and period of the constituent elements in the periodic table. The BMGs discovered to date are classified into seven groups on the basis of a previous result by Inoue. The seven groups are as follows: (G-I) ETM/Ln-LTM/BM-Al/Ga, (G-II) ETM/Ln-LTM/BM-Metalloid, (G-III) Al/Ga-LTM/BMMetalloid, (G-IV) IIA-ETM/Ln-LTM/BM, (G-V) LTM/BM-Metalloid, (G-VI) ETM/Ln-LTM/BM and (G-VII) IIA-LTM/BM, where ETM, Ln, LTM, BM and IIA refer to early transition, lanthanide, late transition, group IIIB–IVB and group IIA-group metals, respectively. The main alloying element of ternary G-I, G-V and G-VII, ternary G-II and G-IV, and ternary G-VI BMGs is the largest, intermediate and smallest atomic radius compared to the other alloying elements, respectively. The main alloying element of ternary BMGs belonging to G-I, G-V, G-VI and G

Classification of Bulk Metallic Glasses by Atomic Size Difference, Heat of Mixing and Period of Constituent Elements and Its Application to Characterization of the Main Alloying Element

The use of electric current to activate the consolidation and reaction-sintering of materials is reviewed with special emphasis of the spark plasma sintering method. The method has been used extensively over the past decade with results showing clear benefits over conventional methods. The review critically examines the important features of this method and their individual roles in the observed enhancement of the consolidation process and the properties of the resulting materials.

/pdf/1000-at-1000-the-effect-of-electric-field-and-pressure-on-vmcyq57hsf.pdf

1000 at 1000: The effect of electric field and pressure on the synthesis and consolidation of materials: a review of the spark plasma sintering method.

Bulk metallic glasses—formed by supercooling the liquid state of certain metallic alloys—have potentially superior mechanical properties to crystalline materials. Here, we report a Co43Fe20Ta5.5B31.5 glassy alloy exhibiting ultrahigh fracture strength of 5,185 MPa, high Young's modulus of 268 GPa, high specific strength of 6.0 × 105 Nm kg−1 and high specific Young's modulus of 31 × 106 Nm kg−1. The strength, specific strength and specific Young's modulus are higher than previous values reported for any bulk crystalline or glassy alloys1,2,3. Excellent formability is manifested by large tensile elongation of 1,400% and large reduction ratio in thickness above 90% in the supercooled liquid region. The ultrahigh-strength alloy also exhibited soft magnetic properties with extremely high permeability of 550,000. This alloy is promising as a new ultrahigh-strength material with good deformability and soft magnetic properties.

/pdf/cobalt-based-bulk-glassy-alloy-with-ultrahigh-strength-and-la04n9pnxc.pdf

Cobalt-based bulk glassy alloy with ultrahigh strength and soft magnetic properties

Super-high strength of over 4000 MPa for Fe-based bulk glassy alloys in [(Fe1-xCox)0.75B0.2Si0.05]96Nb4 system

Fe- and Co-based bulk glassy alloys with ultrahigh strength of over 4000 MPa

Ultra-high strength above 5000 MPa and soft magnetic properties of Co–Fe–Ta–B bulk glassy alloys

Fe-based bulk ferromagnetic glassy alloys with diameters up to 5mm were formed in [(Fe1−xCox)0.75B0.2Si0.05]96Nb4 system by the copper mold casting method. The substitution of Co for Fe caused an increase of glass-forming ability as well as an improvement of mechanical and magnetic properties. The bulk glassy alloys exhibited superhigh fracture strength of 3900–4250MPa, Young’s modulus of 190–210GPa, elastic strain of 0.02, and plastic strain of 0.0025. The bulk glassy alloys also exhibited good soft magnetic properties, i.e., saturation magnetization of 0.84–1.13T, low coercive force of 1.5–2.7A∕m, high permeability exceeding 1.2×104, and Curie temperature of 600–690K.

Baolong Shen

Papers

Cobalt-based bulk glassy alloy with ultrahigh strength and soft magnetic properties

Super-high strength of over 4000 MPa for Fe-based bulk glassy alloys in [(Fe1-xCox)0.75B0.2Si0.05]96Nb4 system

Fe- and Co-based bulk glassy alloys with ultrahigh strength of over 4000 MPa

Ultra-high strength above 5000 MPa and soft magnetic properties of Co–Fe–Ta–B bulk glassy alloys

Superhigh strength and good soft-magnetic properties of (Fe,Co)–B–Si–Nb bulk glassy alloys with high glass-forming ability