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

Small but strong: A review of the mechanical properties of carbon nanotube–polymer composites

There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

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Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

Recently, there has been a rapid growth in research and innovation in the natural fibre composite (NFC) area. Interest is warranted due to the advantages of these materials compared to others, such as synthetic fibre composites, including low environmental impact and low cost and support their potential across a wide range of applications. Much effort has gone into increasing their mechanical performance to extend the capabilities and applications of this group of materials. This review aims to provide an overview of the factors that affect the mechanical performance of NFCs and details achievements made with them.

A review of recent developments in natural fibre composites and their mechanical performance

This review is designed to be a comprehensive source for polymer nanocomposite research, including fundamental structure/property relationships, manufacturing techniques, and applications of polymer nanocomposite materials. In addition to presenting the scientific framework for the advances in polymer nanocomposite research, this review focuses on the scientific principles and mechanisms in relation to the methods of processing and manufacturing with a discussion on commercial applications and health/safety concerns (a critical issue for production and scale-up). Hence, this review offers a comprehensive discussion on technology, modeling, characterization, processing, manufacturing, applications, and health/safety concerns for polymer nanocomposites.

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Review article: Polymer-matrix Nanocomposites, Processing, Manufacturing, and Application: An Overview

The mechanical and microstructural properties of cortical bovine bone have been extensively studied due to the fact that its micro-structural components would significantly reflect the global mechanical behavior of the bone. The objective of this article is to study the elastic modulus and hardness of a bovine cortical bone, in both longitudinal and transverse directions by using nanoindentation technique. The moduli in the longitudinal and transverse directions were recorded as 16.23 GPa and 10.26 GPa, respectively. While the hardness readings in the longitudinal and transverse directions were 0.505 GPa and 0.387 GPa, respectively. According to the result shown, it is suggested that heterogeneous properties of the bone is assumed and the measurements of their properties are highly dependent on tissue types, anatomical location and bone mineral content distribution.

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Measurement of Bovine Bone Properties through Surface Indentation Technique

Proceedings of the International Conference on Shape Memory and Superelastic Technologies and Shape Memory Materials (SMST-SMM 2001), Kumning, 2-6 September 2001

Bonding Behaviors at a NiTi/Epoxy Interface: SEM Observations and Theoretical Study

Graphene and its associated compounds have been identified as extraordinary structural nano-fillers that can tailor the properties of new polymer-based composites with specific functionalities. Gra...

Tailoring specific properties of polymer-based composites by using graphene and its associated compounds

Facial masks cause huge pollution and resource waste, posing a serious threat to the ecological environment and human health. Inspired by lotus leaves, a bioinspired dry Janus all-natural facial mask (J-AFM) has been developed by a simple green-solvent-based electrospinning method. The dry J-AFM can drive water from the outside directionally to dissolve the inner nanofiber layer of nutrients quickly, while keeping the outside dry and delaying moisture evaporation. Compared with commercial wet facial masks, the dry J-AFM can reduce the total weight by 87 and 100% to avoid plastic pollution by using paper-based packaging. In addition, the waste of water and active nutrients can be reduced by 100%. The dry J-AFM with good antibacterial activity and biocytocompatibility can not only avoid the use of preservatives but also shows an obvious skincare effect. This research can trigger the reform of ecofriendly facial masks and guide the chemical industry toward sustainable and healthy development. 

Bioinspired Janus All-Natural Electrospinning Membranes with Directional Water Transport as Ecofriendly Dry Facial Masks

In 2001 it was reported that in North America alone, corrosion to the Oil & Gas pipeline distribution network cost approximately $2-3.3 billion per annum with 10% of that cost being associated with actual failure of the pipeline. In addition pipelines are also susceptible to erosion and mechanical damage producing further losses in pipe structural integrity. This results in high maintenance costs, possibility of adverse environmental consequences and the costly interruption to product transportation and distribution. The cost and technical challenges of adequately addressing repair are significant and greatly increase for underwater applications particularly with increasing water depth. It therefore induces the need of searching for alternative repair techniques involving new advanced materials for ease of installation and application against adverse environmental effects in the long run. Fibre composite materials provide excellent advantages over conventional metals in engineering practices for many decades. These advantages make fibre composite suitable candidate for effective repair technology. This paper provides a comprehensive review on the recent development and future prospect of using these materials for in-air and underwater pipeline external repairs. Various aspects of technical knowhow; benefits and shortcomings of the repair considerations are also presented.

Kin-tak Lau

Papers

Measurement of Bovine Bone Properties through Surface Indentation Technique

Bonding Behaviors at a NiTi/Epoxy Interface: SEM Observations and Theoretical Study

Tailoring specific properties of polymer-based composites by using graphene and its associated compounds

Bioinspired Janus All-Natural Electrospinning Membranes with Directional Water Transport as Ecofriendly Dry Facial Masks

Fibre composites for high pressure pipeline repairs, in-air and subsea: an overview