242 research outputs found

    Stock Market Volatility, Risk Attitude and the Demand for Money in the UK

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    Is stock market volatility an important determinant of money demand in the UK? If yes, what is the driving force behind that effect? In a cointegration framework, we find that volatility in share prices is an important positive determinant of money demand, alongside standard variables and the stock price level. By studying different stock market indexes effects, we find that the risk aversion of investors is an important force behind the effect, implying that the effect is due to investors’ flight to safer assets in times of volatile stock prices

    Does money matter in inflation forecasting?.

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    This paper provides the most fully comprehensive evidence to date on whether or not monetary aggregates are valuable for forecasting US inflation in the early to mid 2000s. We explore a wide range of different definitions of money, including different methods of aggregation and different collections of included monetary assets. In our forecasting experiment we use two non-linear techniques, namely, recurrent neural networks and kernel recursive least squares regression - techniques that are new to macroeconomics. Recurrent neural networks operate with potentially unbounded input memory, while the kernel regression technique is a finite memory predictor. The two methodologies compete to find the best fitting US inflation forecasting models and are then compared to forecasts from a naive random walk model. The best models were non-linear autoregressive models based on kernel methods. Our findings do not provide much support for the usefulness of monetary aggregates in forecasting inflation

    Understanding Microwave Heating in Biomass-Solvent Systems

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    A new mechanism is proposed to provide a viable physical explanation for the action of microwaves in solvent extraction processes. The key innovation is Temperature-Induced Diffusion, a recently-demonstrated phenomenon that results from selective heating using microwaves. A mechanism is presented which incorporates microwave heating, cellular expansion, heat transfer and mass transfer, all of which affect the pressure of cell structures within biomass. The cell-pressure is modelled with time across a range of physical and process variables, and compared with the expected outputs from the existing steam-rupture theory. It is shown that steam-rupture is only possible at the extreme fringes of realistic physical parameters, but Temperature-Induced Diffusion is able to explain cell-rupture across a broad and realistic range of physical parameters and heating conditions. Temperature-Induced Diffusion is the main principle that governs microwave-assisted extraction, and this paves the way to being able to select processing conditions and feedstocks based solely on their physical properties. Graphical abstract Keywords Microwave processing, heat transfer, mass transfer, plant cell rupture, cellular expansion mechanics, solvent extractio

    Quantitative analysis of the residual stress and dislocation density distributions around indentations in alumina and zirconia toughened alumina (ZTA) ceramics

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    This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution 3.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/3.0/Alumina, 10% and 20% ZTA with 1.5mol% yttria stabiliser were subjected to Vickers indentation testing with loads from 1 to 20kg. Cr fluorescence and Raman spectroscopy were applied to the indent centre and around the indentation in order to investigate the origin of the signal, the effect of indentation loads and zirconia phase transformation on the residual stress and plastic deformation in the plastic zone. The results suggested that with very strong laser scattering, the depth resolution of ZTA materials was very poor, which lead to a very significant amount of the signal being collected from the subsurface regions below the plastic zone. It was also found that zirconia phase transformation reduced the compressive residual stress in the alumina matrix within the plastic zone, except at the indentation centre, due to the tensile residual microstress generated by the zirconia phase transformation. In addition, the dislocation density on the indent surface of the ZTA samples was significantly reduced due to the restriction of crack propagation and energy absorption during the phase transformation process. At the indent centre, the zirconia phase transformation was suppressed by the high compressive stress, therefore, no significant difference between alumina and ZTA in terms of their residual stress and dislocation density were observed. Using TEM observation, it was found that the plastic zone microstructure of pure alumina is different from that of ZTA, which is consistent with the Cr fluorescence results

    Microwave assisted large scale sintering of multilayer electroceramic devices

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    The feasibility of employing the microwave methodology for the processing of integrated passive devices (IPDs), nanocrystalline ZnO radials and nano multilayer varistor (MLVs) devices was explored. Methodical microwave sintering experiments were carried out using a multimode, 2.45 GHz microwave applicator. Effect of various experimental parameters such as heating rate, cooling rate, soaking time, sintering temperature etc. on the processing of these device components was investigated in detail. The resultant products were characterized for microstructure, composition and electrical performance. The various stages involved in taking the laboratory research to industrial scale-up production were also examined. The use of microwaves for the processing of MLVs was found to genuinely improve the electrical properties in both small scale (~200 devices/ batch) and large scale (~12000 devices/batch) sintering situations. For a stand alone microwave heating process a back-toback cascading /conveyer belt arrangement is recommended for continuous large scale production. However hybrid heating methodology was found to provide the capability of stacking operations and could be helpful in avoiding the use of ‘casketing’, besides providing the possibility of achieving uniform temperature across a large volume. The technique seems to be attractive in terms of its simplicity, rapidity, economic viability and the superior product performance achieved in all the cases augers well for its general applicability

    Fast regeneration of activated carbons saturated with textile dyes: Textural, thermal and dielectric characterization

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    This study presents an investigation for comparing the regeneration process of two activated carbons saturated with Basic Blue 9 (BB9) and Acid Blue 93 (AB93) using conventional (250–500 °C) and microwave heating (100–300 W). The effect of the textile dye used on the regeneration performance was analyzed by determining their dielectric properties using the perturbation cavity method from 20 to 600 °C and by TG/DTG analysis. The efficacy of the regenerated carbons was investigated by their physical properties characterized by pore structural analysis using N2 adsorption isotherms. Results showed only 3 min are required by microwaves to achieve similar textural parameters obtained by conventional heating at 190 min. The results indicate that the adsorbate plays a determining role on the regeneration efficiency as results of their interaction with the adsorbent, being easily regenerated when AB93 is the adsorbate. The adsorption capacity of microwave regenerated samples for AB93 and BB9 was 192–240 and 154–175 mg/g, respectively. Additionally, the equilibrium isotherms were simulated using the Langmuir and Freundlich isotherms models and the results suggest the textile dye removal is achieved on multilayer adsorption

    Current status of microwave-assisted extraction of pectin

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    There is an urgent need to develop new pectin extraction processes, as the established commercial extraction process damages the pectin (limiting the potential product applications) and is harmful to the environment. Microwave-Assisted Extraction could offer a sustainable route to pectin extraction from a wide range of food wastes and agricultural residues. We present the current state of the art in Microwave-Assisted Extraction of pectin, including the current understanding of the unique heat and mass transfer mechanisms at play during extraction. We review all of the recent literature, testing the commonly held view that microwave heating offers a general improvement in yield and dramatic reductions in processing time compared with conventional solvent extraction. In most of the literature reviewed, there was no evidence that this is the case. However, there is emerging evidence that Microwave-Assisted Extraction can provide processing advantages under some conditions, and that the feedstock dielectric properties and heating rate are important parameters. Preliminary attempts to scale this technology up have shown promise in terms of pectin yield, quality and Life Cycle Analysis compared with conventional extraction. The next steps should be to test more continuous processing concepts for a wider range of feedstocks, and develop more robust Life Cycle Analysis and technoeconomic models. This is the first review paper to focus on the Microwave-Assisted Extraction of pectin

    Investment Opportunities Forecasting: Extending the Grammar of a GP-based Tool

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    In this paper we present a new version of a GP financial forecasting tool, called EDDIE 8. The novelty of this version is that it allows the GP to search in the space of indicators, instead of using pre-specified ones. We compare EDDIE 8 with its predecessor, EDDIE 7, and find that new and improved solutions can be found. Analysis also shows that, on average, EDDIE 8's best tree performs better than the one of EDDIE 7. The above allows us to characterize EDDIE 8 as a valuable forecasting tool
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