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  • Open Access

    ARTICLE

    RECENT ADVANCES IN UNDERSTANDING OF MASS TRANSFER PHENOMENA IN DIRECT METHANOL FUEL CELLS OPERATING WITH CONCENTRATED FUEL

    Q.X. Wua, Y.L. Heb, T.S. Zhaoa,b,*

    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-14, 2011, DOI:10.5098/hmt.v2.3.2001

    Abstract Running direct methanol fuel cells (DMFC) with concentrated fuel is desirable to maximize the specific energy of the fuel cell system and to improve the performance by mitigating the water flooding problem associated with diluted methanol operation. This article provides a comprehensive review of recent advances in understanding mass transport phenomena in DMFCs operating with concentrated fuel. The review starts with elaborating the key issues of mass transport of reactants and products associated with highly-concentrated methanol operation, followed by summarizing and discussing past experimental and numerical investigations into the effects of the membrane electrode assembly More >

  • Open Access

    ABSTRACT

    Towards computational design of Fe(II) chromophores for solar energy conversion

    Elena Jakubikova, David N. Bowman

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 127-128, 2011, DOI:10.3970/icces.2011.019.127

    Abstract The Sun is an abundant source of energy capable of meeting all our energy needs if properly harvested. Some of the ways to utilize solar energy is conversion of sunlight to electricity via photovoltaic solar cells or to chemical fuels via photocatalytic synthetic cells. Many of such systems are designed around a photoactive molecule (a chromophore) anchored to a semiconductor. The conversion of sunlight to electricity occurs via absorption of light by the chromophore, followed by the interfacial electron transfer between the chromophore and semiconductor. We investigate the use of Fe(II)-polypyridine compounds as chromophores in More >

  • Open Access

    ABSTRACT

    Theory and Modelling of Novel Materials for High Energy Batteries

    G. Seifert, S. Leoni, M. Baldoni

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.3, pp. 69-70, 2011, DOI:10.3970/icces.2011.017.069

    Abstract Energy storage is particular important for advanced fuel-efficient vehicles and mobile applications, rechargeable batteries play a key role for such applications. Lithium-ion batteries are today the leading energy storage systems. However, the cathode materials remain insufficient for the use of lithium-ion batteries. To improve this drawback, cathode materials has to be developed further. Therefore, today, most research is focused on the cathode material, and a precise knowledge of the diffusion/transport behaviour of lithium cations inside battery-cathode materials is critical for improving energy density, material properties, and for estimating the impact of chemical substitution. Computer simulations… More >

  • Open Access

    ABSTRACT

    Efficiency improvement of vibration-base piezoelectric energy harvesting device

    Bo Mi Lee, In-Ho Kim, Hyung-Jo Jung

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 19-20, 2011, DOI:10.3970/icces.2011.019.019

    Abstract Vibration energy harvesting, which converts ambient vibration energy into electrical energy, has been an attractive energy scavenging technique to power wireless sensors or low power devices. Even though vibration energy harvesting has drawbacks which are relatively low harvested power and narrow bandwidth, vibration energy scavenging is one of the promising alternative power techniques in that MEMS techniques can be applied to microminiaturize the system. Therefore, many researches have been done to overcome these problems(Lee et al.2010). This paper presents improvement efficiency on piezoelectric vibration energy harvesting device to surmount issues of vibration energy harvesting. Numerical More >

  • Open Access

    ABSTRACT

    Study on Dynamic Energy Absorption Ability of Closed-cell Si-Al Foam Metals Considering Geometry Size

    Yishan Pan, Xiangfeng Lv, Zhonghua Li, XiChun Xiao

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.4, pp. 101-102, 2011, DOI:10.3970/icces.2011.016.101

    Abstract Geometry size has a great influence on energy absorption ability of closed-cell foam metals. Study on energy absorption ability of closed-cell Si-Al foam metals considering geometry size by impact experiment method. The results show that the strain and absorbing energy value are decreasing with the geometry size increasing, and also lead to the hole wall rupture or whole instability. The best height-width ratio for cube and cylinder are 1.0~1.5 and 1.0~2.0, respectively. With the increasing of material diameter, the compressive strength increasing quickly, but the strain reduces. It is clearly that height-width ratio 1.0 is More >

  • Open Access

    ARTICLE

    The Anisotropy of Young's Modulus in Bones

    Ligia Munteanu1, Veturia Chiroiu1, Valeria Mosnegutu1

    CMC-Computers, Materials & Continua, Vol.26, No.2, pp. 137-156, 2011, DOI:10.3970/cmc.2011.026.137

    Abstract In this paper, yet another method for evaluating the elastic modulus for human bones is introduced and investigated. This method adopts the Jankowski and Tsakalakos strain energy function in which, the Born-Mayer energy term is the predominant term for calculations the elastic constants. By taking accounts the directional aspects of the spatial structure of bones, we obtain different values for the Young's modulus depending on the direction of the applied force with respect to the material's structure. The inverse problem analyzed in this paper is solved by inversion of the experimental data. An efficient stopping More >

  • Open Access

    ARTICLE

    Simulation Analysis and Experiment Study of Nanocutting with AFM Probe on the Surface of Sapphire Substrate by Using Three Dimensional Quasi-steady Molecular Statics Nanocutting Model

    Zone-Ching Lin1, Ying-Chih Hsu1

    CMC-Computers, Materials & Continua, Vol.25, No.1, pp. 75-106, 2011, DOI:10.3970/cmc.2011.025.075

    Abstract The three-dimensional quasi-steady molecular statics nanocutting model is used by this paper to carry out simulation analysis of nanocutting of sapphire in order to explore the effects of conical tools with different tip radii of probe and straight-line cutting at different cutting depths, on cutting force. Meanwhile, this paper uses a cutting tool of atomic force microscopy (AFM) with a probe tip similar to a semisphere to conduct nanocutting experiment of sapphire substrate. Furthermore, from the experimental results of nanocutting sapphire substrate, this paper innovatively proposes the theoretical model and equation that the specific down… More >

  • Open Access

    ARTICLE

    Turbulentlike Quantitative Analysis on Energy Dissipation in Vibrated Granular Media

    Zhi Yuan Cui1, Jiu Hui Wu1, Di Chen Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.2, pp. 149-156, 2011, DOI:10.3970/cmes.2011.071.149

    Abstract A quantitative rule of the vibrated granular media's energy dissipation is obtained by adopting the turbulence theory in this letter. Our results show that, similar to the power spectrum in fully developed fluid turbulence as described in Kolmogorov's theory, the power spectrum of vibrated granular media also exhibits a k - 5 / 3 (k is the wave number) power which characterizes the local isotropic flow. What's more, the mean energy dissipation rate in vibrated granular media rises with the increase of particle size and volume ratio. The theoretical results in this letter can be More >

  • Open Access

    ARTICLE

    On the Energy Release Rate at the Crack Tips in a Finite Pre-Strained Strip

    Surkay D. Akbarov1,2, Arzu Turan3

    CMC-Computers, Materials & Continua, Vol.24, No.3, pp. 257-270, 2011, DOI:10.3970/cmc.2011.024.257

    Abstract The influence of the initial finite stretching or compressing of the strip containing a single crack on the Energy Release Rate (ERR) and on the SIF of mode I at the crack tips is studied by the use of the Three-Dimensional Linearized Theory of Elasticity. It is assumed that the edges of the crack are parallel to the face planes of the strip and the ends of the strip are simply supported. The initial finite strain state arises by the uniformly distributed normal forces acting at the ends of the strip. The additional normal forces More >

  • Open Access

    ARTICLE

    A Coupled Magnetic-Elastic-Thermal Free-Energy Model with Hysteretic Nonlinearity for Terfenol-D Rods

    Tian-Zhong Wang1, You-He Zhou1,2

    CMC-Computers, Materials & Continua, Vol.21, No.1, pp. 41-64, 2011, DOI:10.3970/cmc.2011.021.041

    Abstract Based on the thermodynamic theory and the postulates of Jiles and Atherton, a general coupled magnetic-elastic-thermal free-energy model with hysteretic nonlinearity is established for Terfenol-D rods, in which the effect of Weiss molecular field is incorporated. The quantitative agreement between numerical simulation results predicted by the free-energy model and existing experimental data confirms the validity and reliability of the obtained nonlinear theoretical model, and indicates that the free-energy model can accurately capture the nonlinear hysteresis characteristic of Terfenol-D. Meanwhile, the free-energy model is employed to investigate the influences of mechanical stress and the temperature on… More >

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