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

Statistics for Spatial Data.

▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Mitigation and Adaptation Strategies for Global Change

A numerical model has been developed to study particulate fouling in 2D idealized metal foam heat exchangers based on sandstone and sawdust particles. The examination will serve as a stepping stone to better optimize heat exchanger designs. Micron sized poly - disperse sandstone and sawdust particles ha s been used in this investigation, with air as the continuous medium. The mechanism of deposition differs from particle type, sandstone particles showed a higher deposition propensity with a non - uniform layer of fouling whereas the lighter sawdust particles showed negligible deposition. The numerical results obtained through a coupled finite volume and discrete element method showed good agreement with the analytical pressure values obtained from the Darcy equation based on modified porosity of 80 – 100 %, whereas a modified Darcy equation yielded good agreement for porosity values less than 80%.

Poly-disperse particle transport and deposition in idealized porous channels

To ensure reliability and facilitate the strain engineering of zinc oxide (ZnO) nanowires (NWs), it is significant to understand their flexibility thoroughly. In this study, single-crystalline ZnO NWs with rich axial pyramidal I (π1) and prismatic stacking faults (SFs) are synthesized by a metal oxidation method. Bending properties of the as-synthesized ZnO NWs are investigated at the atomic scale using an in situ high-resolution transmission electron microscopy (HRTEM) technique. It is revealed that the SF-rich structures can foster multiple inelastic deformation mechanisms near room temperature, including active axial SFs' migration, deformation twinning and detwinning process in the NWs with growth π1 SFs, and prevalent nucleation and slip of perfect dislocations with a continuous increased bending strain, leading to tremendous bending strains up to 20% of the NWs. Our results record ultralarge bending deformations and provide insights into the deformation mechanisms of single-crystalline ZnO NWs with rich axial SFs.

Exceptional Deformability of Wurtzite Zinc Oxide Nanowires with Growth Axial Stacking Faults.

Production of ultra-clean coal

A concurrent multiscale method has been developed based on the combination of the advanced meshfree method and molecular dynamics (MD). An advanced transition algorithm using regular transition particles was employed to ensure the compatibility of both displacements and their gradients. An effective local quasi-continuum approach is also applied to obtain the equivalent continuum strain energy density based on the atomistic potentials and Cauchy-Born rule. The influences of the size of transition region and the number of transition particles are investigated thoroughly. It has been demonstrated that the present multiscale simulation technique is very accurate and stable, and it has very good potential to develop a practical simulation tool for the multiscale systems in computational mechanics.

https://espace.library.uq.edu.au/view/UQ:131879/A5.1.pdf

A Coupled Meshfree Technique/Molecular Dynamics Method for Multiscale Stress and Deformation Analysis in Computational Mechanics

Industrial transformer is one of the most critical assets in the power and heavy industry. Failures of transformers can cause enormous losses. The poor joints of the electrical circuit on transformers can cause overheating and results in stress concentration on the structure which is the major cause of catastrophic failure. Few researches have been focused on the mechanical properties of industrial transformers under overheating thermal conditions. In this paper, both mechanical and thermal properties of industrial transformers are jointly investigated using finite element analysis (FEA). Dynamic response analysis is conducted on a modified transformer FEA model, and the computational results are compared with experimental results from literature to validate this simulation model. Based on the FEA model, thermal stress is calculated under different temperature conditions. These analysis results can provide insights to the understanding of the failure of transformers due to overheating, therefore are significant to assess winding fault, especially to the manufacturing and maintenance of large transformers.

/pdf/numerical-investigation-of-mechanical-and-thermal-dynamic-1w8vk9ggw9.pdf

YuanTong Gu

Papers

Poly-disperse particle transport and deposition in idealized porous channels

Exceptional Deformability of Wurtzite Zinc Oxide Nanowires with Growth Axial Stacking Faults.

Production of ultra-clean coal

A Coupled Meshfree Technique/Molecular Dynamics Method for Multiscale Stress and Deformation Analysis in Computational Mechanics

Numerical investigation of mechanical and thermal dynamic properties of the industrial transformer