Search Results - (Author, Cooperation:Y. C. Lam)

2013-05-03

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Argonaute Proteins/*chemistry/*metabolism ; Breast Neoplasms/genetics/metabolism/mortality/pathology ; Cell Hypoxia/genetics/*physiology ; Cell Line, Tumor ; Cell Survival ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; MicroRNAs/biosynthesis/chemistry/genetics/*metabolism ; Neoplasm Invasiveness ; Nucleic Acid Conformation ; Phosphorylation ; Phosphotyrosine/metabolism ; Prognosis ; Protein Binding ; RNA Precursors/chemistry/genetics/metabolism ; Receptor, Epidermal Growth Factor/*metabolism ; Ribonuclease III/metabolism ; Survival Analysis

1460-2695

Blackwell Publishing Journal Backfiles 1879-2005

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Previous investigations have shown that the introduction of a compressive residual stress at critical locations enhances the fatigue life of welds. In the present study a combination of heat and applied stress is used to induce a compressive residual stress at critical locations such as the weld toe. The theory of the technique is discussed and an experimental study is carried out to investigate the effect of the technique on the fatigue behaviour of transverse butt welded specimens made from C-Mn steel.

Electronic Resource

1460-2695

Blackwell Publishing Journal Backfiles 1879-2005

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract— The improvement of a material's toughness has significant industrial applications. An example is the manufacture and maintenance of commercial gas containers made in the form of aluminium cylinders; a challenging design problem since they are susceptible to crack growth under a static load (internal pressure). In this investigation a new thermo-mechanical technique was used to improve the apparent fracture toughness. This could increase significantly the safety margin and life of the cylinders. The determination of fracture toughness was carried out using a newly developed small cylindrical specimen which has a considerable cost advantage over the standard compact tension specimen. Experiments on aluminium 6351-T6 cylindrical specimens confirmed the possibility of improving the toughness of this alloy.

Electronic Resource

1460-2695

Blackwell Publishing Journal Backfiles 1879-2005

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Fatigue crack growth under biaxial loading for long cracks subjected to low cyclic stress levels was investigated. The biaxial stress ratio λ ranging from -0.5 to + 1.0 was considered. The strain energy density factor range was used as the criterion for predicting the crack growth rates and crack path. The agreement between prediction and experimental results was reasonable for crack growth rates and marginal for crack paths. The investigation highlighted the inherent difficulties for crack path prediction and indicated the increased sensitivity to initial crack angle and biaxial stress ratio when the biaxial stress ratio approaches unity.

Electronic Resource

1572-8986

Numerical modeling ; plasma spraying ; particle size ; injection velocity

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Technology

Abstract A process control chart is proposed for DC plasma spraying process based on the in-flight simulation of the injected states of the particles determined by computational fluid dynamics analysis (via FLUENT V4.3). The chart consists of five regions, i.e., the unmelted, melted, vaporized, escaped, and rebounded, which represent the various states of the particles at impact on the substrate. The X and Y axes of the chart are particle entry conditions, i.e., diameter (ranging from 20 to 100 μm) and injection velocity (between 10 to 50 m/s), respectively. The regions indicate the fate of the particle on impact. A grid-array of (14×11) entry conditions is simulated in developing the chart. The proposed chart is aimed at providing a general guideline for plasma spraying process in achieving a thoroughly melted particle on arrival at the substrate to be coated.

Electronic Resource

0029-5981

finite elements ; substructuring ; static condensation ; Engineering ; Engineering General

Wiley InterScience Backfile Collection 1832-2000

Mathematics

Technology

This paper describes and analyses the implementation of two static condensation algorithms used to exploit the regular patterns created by two schemes of regular mesh substructuring. Computer resources required by the implementation are assessed in terms of the number of multiplications, the total CPU time, the core and the disk storage requirements. It is discovered that, when implemented for the regular mesh substructuring, the newly proposed condensation algorithm is generally more cost effective than the one proposed by Han and Abel, and modified for the regular mesh substructuring by the present authors.

7 Ill.

Electronic Resource

0748-8025

Engineering ; Engineering General

Wiley InterScience Backfile Collection 1832-2000

Mathematics

Technology

A new technique of multi-level substructuring based on a regular mesh is presented. The technique takes advantage of the physical symmetry and repetitivity generated by the regular mesh. A special node-numbering/addressing system is developed to exploit the symmetry which results in the stiffness matrices not only being symmetrical about the leading diagonal, but a regular pattern emerging with respect to the other diagonal. The same pattern exists for their inverses. A new condensation scheme is used to take full advantage of the regular patterns. As a result, only about a quarter of the stiffness matrices and their inverses need to be processed, as compared to half when using the conventional method.Based on the technique, a two-dimensional finite-element analysis program FEMSUB has been implemented in the University's VAX network. Through a number of numerical tests, it is discovered that the new technique can result in savings of both core storage and computing time. The savings become more significant when the scale of a problem increases. The investigation indicates that the core storage requirement decreases when using substructures of higher levels. However, for computational efficiency, both the level of substructuring and the number of repeated substructures have an effect. Thus, a dimensionless parameter R (number of substructures used/maximum number of substructures) has been introduced to correlate the effect of the technique on computational efficiency.

13 Ill.

Electronic Resource