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Li J.,Hefei University of Technology | Li J.,Cityint Advanced Research Center | Xue C.J.,City University of Hong Kong | Xu Y.,Hefei University of Technology
2011 IEEE/IFIP 19th International Conference on VLSI and System-on-Chip, VLSI-SoC 2011 | Year: 2011

Modern high performance Chip Multiprocessor (CMP) systems rely on large on-chip cache hierarchy. As technology scales down, the leakage power of present SRAM based cache gradually dominates the on-chip power consumption, which can severely jeopardize system performance. The emerging nonvolatile Spin Transfer Torque RAM (STT-RAM) is a promising candidate for large on-chip cache because of the ultra low leakage power. However, the write operations on STT-RAM suffer from considerably higher energy as well as longer latency compared with SRAM which will make STT-RAM in trouble for write-intensive workloads. In this paper, we propose to integrate SRAM with STT-RAM to construct a novel hybrid cache architecture for CMPs. We also propose dedicated microarchitectural mechanisms to make the hybrid cache robust to workloads with different write patterns. Extensive simulation results demonstrate that the proposed hybrid scheme is adaptive to variations of workloads. Overall power consumption is reduced by 37.1% and performance is improved by 23.6% on average compared with SRAM based static NUCA under the same area configuration. © 2011 IEEE. Source

Zhu P.,City University of Hong Kong | Lei Z.X.,City University of Hong Kong | Lei Z.X.,Cityint Advanced Research Center | Lei Z.X.,University of Science and Technology of China | And 2 more authors.
Composite Structures | Year: 2012

This paper mainly presents bending and free vibration analyses of thin-to-moderately thick composite plates reinforced by single-walled carbon nanotubes using the finite element method based on the first order shear deformation plate theory. Four types of distributions of the uniaxially aligned reinforcement material are considered, that is, uniform and three kinds of functionally graded distributions of carbon nanotubes along the thickness direction of plates. The effective material properties of the nanocomposite plates are estimated according to the rule of mixture. Detailed parametric studies have been carried out to reveal the influences of the volume fractions of carbon nanotubes and the edge-to-thickness ratios on the bending responses, natural frequencies and mode shapes of the plates. In addition, the effects of different boundary conditions are also examined. Numerical examples are computed by an in-house finite element code and the results show good agreement with the solutions obtained by the FE commercial package ANSYS. © 2011 Elsevier Ltd. Source

Yu L.,Cityint Advanced Research Center | Yu L.,City University of Hong Kong | Li W.-W.,Cityint Advanced Research Center | Li W.-W.,Hefei University of Technology | And 2 more authors.
Applied Microbiology and Biotechnology | Year: 2011

Adsorption and decolorization kinetics of methyl orange (MO) by anaerobic sludge in anaerobic sequencing batch reactors were investigated. The anaerobic sludge was found to have a saturated adsorption capacity of 36±1 mg g MLSS-1 to MO. UV/visible spectrophotometer and high-performance liquid chromatography analytical results indicated that the MO adsorption and decolorization occurred simultaneously in this system. This process at various substrate concentrations could be well simulated using a modified two-stage model with apparent pseudo first-order kinetics. Furthermore, a noncompetitive inhibition kinetic model was also developed to describe the MO decolorization process at high NaCl concentrations, and an inhibition constant of 3.67 g NaCl l-1 was estimated. This study offers an insight into the adsorption and decolorization processes of azo dyes by anaerobic sludge and provides a better understanding of the anaerobic dye decolorization mechanisms. © 2011 Springer-Verlag. Source

Wang C.,City University of Hong Kong | Wang C.,Cityint Advanced Research Center | Wang C.,Hefei University of Technology | Li S.,City University of Hong Kong | And 3 more authors.
Nanoscale | Year: 2012

We investigated the adsorption of three aromatic amino acids - phenylalanine, tyrosine, and tryptophan - on the sidewalls of a number of representative single-walled carbon nanotubes (SWNTs) using density-functional tight-binding calculations, complemented by an empirical dispersion correction. The armchair (n, n) SWNTs (n = 3-12) and zigzag (n, 0) SWNTs (n = 4-12) were thoroughly examined. We found that the most stable amino acid/SWNT complexes for different SWNTs have similar local structures, and that the distance between the amino acid and SWNT is about 3 Å. Owing to the π-π and H-π stacking interactions, the benzene and indole rings are not exactly parallel to the SWNTs but instead lie at a small angle. We also investigated the diameter and chirality dependences of binding energies and found that SWNT (5, 0) has an especially large binding energy that can be used for SWNT identification or selection. © 2012 The Royal Society of Chemistry. Source

Lei Z.X.,City University of Hong Kong | Lei Z.X.,University of Science and Technology of China | Lei Z.X.,Cityint Advanced Research Center | Liew K.M.,City University of Hong Kong | And 3 more authors.
Composite Structures | Year: 2013

This paper presents the buckling analysis of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates under various in-plane mechanical loads, using the element-free kp-Ritz method. The first-order shear deformation plate theory is applied and a set of mesh-free kernel particle functions are used to approximate two-dimensional displacement fields. Effective properties of materials of the plates reinforced by single-walled carbon nanotubes (SWCNTs) are estimated through a micromechanical model based on either the Eshelby-Mori-Tanaka approach or the extended rule of mixture. Comparison study and numerical simulations with various parameters are conducted to assess efficacy and accuracy of the present method for analysis of buckling of SWCNT-reinforced composite plates. Results demonstrate that the change of carbon nanotube volume fraction, plate width-to-thickness ratio, plate aspect ratio, loading condition and temperature have pronounced effects on buckling strength of CNTRC plates as well as the boundary condition. © 2012 Elsevier Ltd. Source

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