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A new type of high-temperature fuel cell using solid carbon as fuel, which is called a direct carbon fuel cell (DCFC), has recently attracted scientific and industrial attention due to its excellent electrochemical efficiency, less production of CO2, and no need of CO2 separation. However, the state-of-the-art technology of the DCFC is still in an idea-developing stage, mainly because of fuel-related difficulties: discontinuous fuel supply and very limited formation of a triple-phase boundary. Hence, this study was devoted to developing a new way to maximize the formation of TPBs by using a porous Ni anode and realizing continuous fuel supply through various methods.

In this paper, we solve the location-based VANET Routing Protocol problem which is due to high mobility from vehicles and complex roadways in Urban Environments. Today, a lot of location-based Routing algorithms have appeared and we will research to consider vehicles behavior. Position information that is received by V2V Communications which is Wireless Access in Vehicular Environments (WAVE) can be used to calculate vehicles' moving directions and also vehicles' relative moving directions. These are possible to predict through the road feature and vehicles' moving direction. We propose this protocol to enhance the node searching and route optimizing accuracy through using that calculated information.

ZnO quantum dots dispersed in a silica matrix were synthesized from a TEOS:Zn(NO(3))(2) solution by a one-step aerosol-gel method. It was demonstrated that the molar concentration ratio of Zn to Si (Zn/Si) in the aqueous solution was an efficient parameter with which to control the size, the degree of agglomeration, and the microstructure of ZnO quantum dots (QDs) in the SiO(2) matrix. When Zn/Si ≤ 0.5, unaggregated quantum dots as small as 2 nm were distributed preferentially inside SiO(2) spheres. When Zn/Si ≥ 1.0, however, ZnO QDs of ∼7 nm were agglomerated and reached the SiO(2) surface. When decreasing the ratio of the Zn/Si, a blue shift in the band gap of ZnO was observed from the UV/Visible absorption spectra, representing the quantum size effect. The photoluminescence emission spectra at room temperature denoted two wide peaks of deep-level defect-related emissions at 2.2-2.8 eV. When decreasing Zn/Si, the first peak at ∼2.3 eV was blue-shifted in keeping with the decrease in the size of the QDs. Interestingly, the second visible peak at 2.8 eV disappeared in the surface-exposed ZnO QDs when Zn/Si ≥ 1.0.

A gas-phase, one-step method for producing various aerosol carbon nanostructures is described. The carbon nanostructures can be selectively tailored with either straight, coiled, or sea urchin-like structures by controlling the size of Ni-Al bimetallic nanoparticles and the reaction temperature. The carbon nanostructures were grown using both conventional spray pyrolysis and thermal chemical vapor deposition. Bimetallic nanoparticles with catalytic Ni (guest) and non-catalytic Al (host) matrix were reacted with acetylene and hydrogen gases. At the processing temperature range of 650-800 °C, high concentration straight carbon nanotubes (S-CNTs) with a small amount of coiled carbon nanotubes (C-CNTs) can be grown on the surface of seeded bimetallic nanoparticle size100 nm, resulting from consumption of the melting Al matrix sites; sea urchin-like carbon nanotubes (SU-CNTs) of small diameter (∼10±4 nm) can be grown on the bimetallic nanoparticle size100 nm, resulting from the significant size reduction of the available Ni sites due to thermal expansion of molten Al matrix sites without consumption of Al matrix. However, at the processing temperature range of 500-650 °C, C-CNTs can be grown on the bimetallic nanoparticle size100 nm due to the presence of Al matrix in the bimetallic nanoparticles; SU-CNTs of large diameter (∼60±13 nm) can also be grown on the bimetallic nanoparticle size100 nm due to the isolation of Ni sites in the Al matrix.

Controlled synthesis of nanoparticles has been carried out using laser beam irradiation on aggregates forming in a flame. This coalescence enhanced method transforms titania aggregates into much smaller unagglomerate spherical anatase nanoparticles by reducing the characteristic time of coalescence of nanoparticles. These transformed nanoparticles exhibit not only better thermal stability, but also unusually small grain growth during a simple pressureless sintering, which ultimately lead to a full dense bulk ceramic with 60 nm grains. Such small grain size in full dense ceramics has not been achieved before without employing special sintering techniques. This would be attributed not only to the successful control of size and morphology of nanoparticles, but also to the synthesis of oxygen vacancy free particles, which was confirmed from Raman spectroscopy.

The ability to manipulate miniature object assemblies with well-defined structures in a controllable manner is of both fundamental and applied interests. This article presents general strategies, with nanospheres as building blocks, to engineer mesoscopic spherical architectures via a process of evaporation-driven self-assembly in aerosol droplets. Uniform magnetite iron oxide (Fe(3)O(4), approximately 2.5 nm), silica (SiO(2), approximately 15 nm), and cupric oxide (CuO, approximately 6 nm) nanoparticles were employed for the structural architecture. The method enables microstructural control of the self-assembled mesospheres by tuning the competition between solvent evaporation and solute diffusion within an aerosol droplet. Furthermore, we have demonstrated it is technically feasible to assemble surface-dissimilar binary components, i.e., charge-stabilized hydrophilic SiO(2) and hydrophobic ligand-capped Fe(3)O(4) nanoparticles, into hierarchical composite structures, which could be extended for preparation of more hierarchically textured materials with desired functionalities.

It has been a big challenge to explore a direct relation of experimental parameters such as pH, electrolyte concentration, particle size, and temperature with the final structures of aggregates, because Monte Carlo simulations have been performed on the basis of arbitrarily chosen sticking probability. We attempted to incorporate colloidal theory to Monte Carlo simulations for two model systems of CuO- and SiO(2)-water systems, so as to resolve this difficulty. Conducting three-dimensional off-lattice MC simulations at various pHs for both systems, we investigated effects of pH on fractal structures of aggregates, encompassing the whole aggregation regime from diffusion-limited cluster-cluster aggregation to reaction-limited cluster-cluster aggregation. Moreover, developing a functional analysis, we found an explicit correlation between experimental parameters, sticking probability, and the fractal dimension of aggregates for both systems.

Recent research on nanofluids has offered particle clustering as a possible mechanism for the abnormal enhancement of the effective thermal conductivity $(k)$ when nanoparticles are dispersed in liquids. This paper was devoted to verify experimentally and theoretically the significance of the effect by altering the cluster structure, size distribution, and thermal conductivity of solid particles in water. Starting with well dispersed ${\text{SiO}}_{2}$ sols in water as a reference system, we control the aggregation kinetics by adjusting $p\text{H}$. Contrary to previous model predictions, the present experiment showed that clustering did not show any discernable enhancement in the thermal conductivity even at high volume loading. A series of fractal model calculations not only suggested that the conductive benefit due to clustering might be completely compensated by the reduced convective contribution due to particle growth, but also recommended the need for higher thermal conductivity and optimized fractal dimension of particles for maximizing the clustering effect.

Although recent experiments have revealed that nanofluids have superior thermal conductivities to base fluids, the inherent physics are not fully understood. In this study, an interfacial layer, competing with Brownian motion as a corresponding mechanism, is conceptually connected with the surface-charge-induced electrical double layer. By applying colloidal science, the first explicit equations for the thickness and thermal conductivity of the layer are obtained. A fractal model including the new concept of the layer is developed. The model predictions are compared with experimental data for effects of pH, temperature, volume fraction, and primary particle size of CuO-water nanofluids.

Aluminum nanoparticles are being considered as a possible fuel in advanced energetic materials application. Of considerable interest therefore is a knowledge of just how reactive these materials are, and what the effect of size on reactivity is. In this paper we describe results of size resolved oxidation rate using a recently developed quantitative single particle mass spectrometer (SPMS). Aluminum nanoparticles used were either generated by DC Arc discharge or laser ablation, or by use of commercial aluminum nanopowders. These particles were oxidized in an aerosol flow reactor in air for specified various temperatures (25-1100 degrees C), and subsequently sampled by the SPMS. The mass spectra obtained were used to quantitatively determine the elemental composition of individual particles and their size. We found that the reactivity of aluminum nanoparticles is enhanced with decreasing primary particle size. Aluminum nanoparticles produced from the DC Arc, which produced the smallest primary particle size (approximately 19 nm), were found to be the most reactive (approximately 68% aluminum nanoparticles completely oxidized to aluminum oxide at 900 degrees C). In contrast, nanopowders with primary particle size greater than approximately 50 nm were not fully oxidized even at 1100 degrees C (approximately 4%). The absolute rates observed were found to be consistent with an oxide diffusion controlled rate-limiting step. We also determined the size-dependent diffusion-limited rate constants and Arrehenius parameters (activation energy and pre-exponential factor). We found that as the particle size decreases, the rate constant increases and the activation energy decreases. This work provides a quantification of the known pyrophoric nature of fine metal particles.

This paper studies a series of reconfiguration processes corresponding to a series of traffic demand changes in a WDM (Wavelength Division Multiplexing) optical network. The proposed reconfiguration framework consists of two objective functions, a reconfiguration process, and a reconfiguration policy. The two objective functions are AHT (objective function of minimizing Average Hop distance of Traffic) and NLC (objective function of minimizing Number of Lightpath routing Changes). The reconfiguration process finds a set of non-dominated solutions using the PEAP (Pareto Evolutionary Algorithm adapting the Penalty method) that optimizes two objective functions by using the concept of Pareto optimality. The reconfiguration policy picks a solution from the set of non-dominated solutions using the MDA (Markov Decision Action). Experimental results show that our reconfiguration framework incorporating the PEAP and the MDA yields efficient performance in the entire series of reconfiguration processes.

Computational fluid dynamics simulations incorporating supersonic turbulent gas flow models and a droplet breakup model are performed to study supersonic gas atomization for producing micron-sized metal powder particles. Generally such atomization occurs in two stages: a primary breakup and a secondary breakup. Since the final droplet size is primarily determined by the secondary breakup, parent droplets of certain sizes (1 to 5 mm) typically resulting from the primary breakup are released at the corner of the nozzle and undergo the secondary breakup. A comparison of flow patterns with and without the introduction of a liquid melt clearly indicates that the mass loading effect is quite significant as a result of the gas–droplet interactions. The flow pattern change reasonably explains why the final droplets have a bimodal mass size distribution. The transient size changes of the droplets are well described by the behavior of the Weber number. The present results based on the 1 mm parent droplets best fit previous experimental results. Moreover, the effects of inlet gas pressure and temperature are investigated in an attempt to further reduce droplet size.

Here we study the interaction of a nanosecond laser pulse with a nanoparticle to explore the mechanism of energetic ion formation and in particular the particle size dependence. Multiphoton ionization and the subsequent electron impact ionization accompanied by inverse Bremsstrahlung process are determined appropriate for generation of multiple charged ions. The Coulomb expansion of a positive ion cloud is then calculated with molecular dynamics simulations, resulting in temporal evolution of ions, a radial distribution of kinetic energy of ions, and size-dependency of the ion kinetic energy. A mass spectrum peak of ion simulated by the present model is found comparable to the experimental data. Alternatively, a direct measurement of kinetic energy is also explained by the model.

The energy accommodation coefficient (EAC), which is used to characterize gas-surface interactions, was experimentally estimated at high temperatures. A method utilizing laser irradiation to heat up nanoparticles that are generated in a flame was proposed. From the obtained dependence of particle temperature upon laser power, the EAC was derived to be approximately equal to 0.005, which agrees nicely with our recent rigorous theoretical result. It indicates that the efficiency of heat transfer between gas and particles is sufficiently small in high temperature system at large Knudsen numbers.

The light absorption of silica nanoparticles generated in a flame has been measured in visible light. It was revealed that the frequency dependence of the light absorption coefficient is nonexponential. Its absolute value in the forbidden band was found to be unusually high. This behavior of light absorption is ascribed to a narrowing of the energy gap due to a high concentration of structural defects that appear during particle generation and growth at high temperatures.

We observe an intense ion pulse from nanocomposite thermite reactions, which we temporally probe using a recently developed temperature jump/time of flight mass spectrometer. These ion pulses are observed to be much shorter in duration than the overall thermite reaction time. Ion ejection appears in stages as positive ions are ejected prior to nanocomposite thermite ignition, and ignition of the thermite mixtures leads to a second ionization step which is primarily dominated by negative species. The positive species are identified from mass spectrometric measurements and the results show that the positive ion species are comprised of Na ions with minor species of Al and K ions. This observation can be explained by a diffusion based ion-current mechanism, in which strong Al ion diffusion flux formed through the oxide shell, and the surface Na and K ions from salt contaminations are ejected by the strong electrostatic repulsion. The fact that the negative ionization step occurs during the ignition event sug...

Carbon black, activated carbon and carbon nanotube have been used as supporting materials for precious metal catalysts used in fuel cell electrodes. One-step flame synthesis method is used to coat 2-5nm Pt dots on flame-generated carbon particles. By adjusting flame temperature, gas flow rates and resident time of particles in flame, we can obtain Pt/C nano catalyst-support composite particles. Additional injection of hydrogen gas facilitates pyrolysis of Pt precursor in flame. The size of as-incepted Pt dots increases along the flame due to longer resident time and sintering in high temperature flame. Surface coverage and dispersion of the Pt dots is varied at different sampling heights and confirmed by Transmission electron microscopy (TEM), Energy-dispersive spectra (EDS) and X-ray diffraction (XRD). Crystalline and surface bonding groups of carbon are investigated through X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The electro-catalytic property of Pt/C composites for the application to catalytic electrode PEMFC are also investigated by Cyclic voltammetry (CV).