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[en] Claims have emerged recently, of high hydrogen storage capacities at room temperature and above, for carbons such as single-wall and multi-walled nanotubes. We have been unable to verify any claims of high capacities at room temperature and low pressure. For (10,10) single wall carbon nanotubes, we used a computer controlled Sievert's apparatus to measure an adsorption at RT of 0.07 wt% gravimetric density at 1 bar, typical of what is expected on the basis of BET surface area measurements for carbons. At high pressures of > 60 bar and temperatures of 80K gravimetric densities up to ∼ 8 wt% are obtained, but more typically ∼ 7 wt% after a few adsorption desorption cycles. These values and isotherm shapes can be attributed to rearrangement of the rope structure that is formed by condensed nanotubes. Certain fullerites can also exhibit adsorption/desorption cycle dependent capacity, ranging from 2.5 to 4 wt% at 80K and 120 bar. (author)

[en] Several investigations have recently been undertaken in order to achieve a more complete understanding of the radiation-damage mechanisms in A₂B₂O₇ pyrochlore-structure compounds. The present work represents the first systematic study of the irradiation-induced amorphization of a pyrochlore with A- and B-site cation valences of +2 and +5, respectively. Relatively large single crystals of Cd₂Nb₂O₇ were grown for these experiments. In situ ion-irradiation experiments were carried out in a transmission electron microscope in conjunction with ex situ Rutherford backscattering measurements of ion-irradiated Cd₂Nb₂O₇ single crystals. Cd₂Nb₂O₇ can be amorphized in situ by Ne or Xe ions at temperatures up to 480 and 620 K, respectively. At room temperature, the amorphization fluence was 36 times higher for 280 keV Ne⁺ than for 1200 keV Xe²⁺, corresponding to a displacement dose that was higher by a factor of 3. Disordering of Cd and Nb over the available cation sites occurs at intermediate ion doses prior to amorphization. The temperature dependence of the amorphization dose is modeled, and the results are compared to those of a previous model. The bulk-sample Rutherford backscattering spectroscopy (RBS) results were generally consistent with the in situ TEM measurements. Effects of crystallographic orientation and ion charge state had relatively little effect on the damage accumulation in bulk crystals. The RBS data are consistent with a defect-accumulation, cascade-overlap model of amorphization of Cd₂Nb₂O₇, as are the in situ TEM observations

[en] Secondary lead, i.e. material produced by the recycling of lead-acid batteries has become the primary source of lead in much of the world. This has been important to the secondary lead industry as other uses have dwindled, e.g. lead based pigments, chemicals, fuel additives, solders and CRT glasses. Presently, battery manufacturing accounts for greater than 80% of lead consumption while recycled lead accounts for approximately the same market share of lead supply. These two facts strongly demonstrate the battery manufacturing and recycled lead are intimately coupled in everyday life. In this paper we will explore how recycled lead has become the material of choice for battery construction through the development of a recovery and refining process that exceeds the industries requirements. Particular focus will be on addressing the results presented by Prengaman on the effects of contaminant or tramp elements on gassing in lead-acid batteries. (author)

[en] Lithium batteries are characterized by high specific energy, high efficiency and long life. These unique properties have made lithium batteries the power sources of choice for the consumer electronics market with a production of the order of billions of units per year. These batteries are also expected to find a prominent role as ideal electrochemical storage systems in renewable energy plants, as well as power systems for sustainable vehicles, such as hybrid and electric vehicles. However, scaling up the lithium battery technology for these applications is still problematic since issues such as safety, costs, wide operational temperature and materials availability, are still to be resolved. This review focuses first on the present status of lithium battery technology, then on its near future development and finally it examines important new directions aimed at achieving quantum jumps in energy and power content. (author)

[en] Effects of carbon black in micro-porous layer (MPL) on the performance of H₂/air proton exchange membrane fuel cells (PEMFCs) were studied and characterized extensively. Physical properties of gas diffusion layers (GDLs) involving surface morphology, gas permeability, hydrophilic/hydrophobic porosity and electron conductivity were examined. To construct an effective bi-functional pore structure, a novel MPL using composite carbon black consisting of Acetylene Black and Black Pearls 2000 carbon was presented for the first time. An optimal cell performance with the maximum power density of 0.91 W cm^-2 was obtained by the MPL containing 10 wt.% Black Pearls 2000 in composite carbon black

[en] A paraffin/expanded graphite composite phase change thermal energy storage material was prepared by absorbing the paraffin into an expanded graphite that has an excellent absorbability. In such a composite, the paraffin serves as a latent heat storage material and the expanded graphite acts as the supporting material, which prevents leakage of the melted paraffin from its porous structure due to the capillary and surface tension forces. The inherent structure of the expanded graphite did not change in the composite material. The solid-liquid phase change temperature of the composite PCM was the same as that of the paraffin, and the latent heat of the paraffin/expanded graphite composite material was equivalent to the calculated value based on the mass ratio of the paraffin in the composite. The heat transfer rate of the paraffin/expanded graphite composite was obviously higher than that of the paraffin due to the combination with the expanded graphite that had a high thermal conductivity. The prepared paraffin/expanded graphite composite phase change material had a large thermal storage capacity and improved thermal conductivity and did not experience liquid leakage during its solid-liquid phase change

[en] In this study, a conjugate gradient method based on an inverse algorithm is applied to estimate the unknown space and time dependent convection heat transfer coefficient of an annular fin. While knowing the temperature or strain history at the measuring positions of the fin, the convection heat transfer coefficient between the fin and the ambient fluid can be successfully computed. No prior information is needed on the functional form of the unknown convection heat transfer coefficient; and thus, the present study is classified as the function estimation inverse calculation. A particular feature in this study is that the thermal and strain fields are coupled, which makes solving the inverse problem a highly challenging task. The accuracy of the inverse analysis is examined by using the simulated temperature or strain measurements. Results show that excellent estimations of the convection heat transfer coefficient, temperature distributions and thermal stress distributions can be obtained for all the cases considered in this study

[en] Performance analysis of three phase induction motors under supply voltage unbalance conditions is normally conducted using the well-known symmetrical components analysis. In this analysis, the voltage unbalance level at the terminals of the machine is assessed by means of the NEMA or IEC definitions. Both definitions lead to a relatively large error in predicting the performance of a machine. A method has recently been proposed in which, in addition to the voltage unbalance factor (VUF), the phase angle has been taken into account in the analysis. This means that the voltage unbalance factor is regarded as a complex value. This paper shows that although the use of the complex VUF reduces the computational error considerably, it is still high. This is proven by evaluating the derating factor of a three phase induction motor. A method is introduced to determine the derating factor precisely using the complex unbalance factor for an induction motor operating under any unbalanced supply condition. A practical case for derating of a typical three phase squirrel cage induction motor supplied by an unbalanced voltage is studied in the paper

[en] Lithium metal phosphate materials are the newest generation of active materials. With the limited number of cathode materials available at present and the prevalence of transition metal oxide cathodes, phosphates are able to answer the rising safety concerns surrounding the oxide chemistry. These inherent safety limitations have until now prevented lithium ion batteries in general from entering the large format applications markets such as electric and hybrid electric vehicles. Iron-based olivine phosphate has been the focus of extensive research: intrinsic thermal stability and continual improvement of its performance characteristics have geared the industry to a fast track adoption of this chemistry for the larger format applications. Recently developed vanadium-based phosphates possess operating voltages of 3.65 V for Li₃V₂(PO₄)₃ and 4.05 V for LiVPO₄F, both of which are higher than the iron-based phosphate. The high power capability of Li₃V₂(PO₄)₃ makes it ideal for applications that require power; LiVPO₄F on the other hand has high energy and a desirable cycling characteristic that makes it ideal for energy-demanding applications such as PHEV and EV. These materials are the best fit for the ever-increasing demand for energy, power and thermal stability that is essential in the large format arena. (author)