bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative structural investigations of mechanically‐treated MgO powder (I) type of stress: Pressure and shear
Authors: Kretzschmar U. , Ebert I. , Steinike U. , Hennig H.‐P. 
Published: July 2007

AbstractMgO is treated up to 95 hours in a vibration mill by means of pressure and shear. The. type and distribution of the mechanically‐induced disorder in the grains of the powder is investigated by X‐ray diffraction and electronparamagnetic resonance (EPR). The disorder investigated by the two methods is characterized by an almost equal temperature behaviour which is determined by strongly disturbed surface‐near ranges of the individual grains. By means of mechanical treatment a high dislocation density is achieved in these ranges. The EPR‐spectra are assigned to V‐centres and O−‐ions in strongly distorted ranges.
On the influence of the pre‐ageing temperature on the reversion behaviour of an Al‐4.5 at.% Zn‐2.0 at.% Mg alloy
Authors: Gueffroy B. , Löffler H. 
Published: July 2007

AbstractThe reversion behaviour of an Al‐Zn(4.5)‐Mg(2.0) alloy was investigated by SAXS in dependence of the pre‐ageing temperature, Tpre, (ranging between 60°C and 100°C) and the reversion temperature, Trev, (120°C till 200°C) starting with precipitates having a radius of (1.2 ± 0.1) nm and (1.5 ± 0.1) nm, respectively. During the reversion treatment applied up to Trev = 160°C three stages could be distinctly distinguished, namely the dissolution of unstable zones, the growth of the stable zones on the expense of the dissolved one, and at last the coarsening of the precipitates by the OSTWALD‐ripening process, where the structure changes become independent of the pre‐history (start radius). The change of Tpre from 60°C to 100°C does not influence the structure changes going on at Trev, that means between 60°C and 100°C the same type of G.P. zones grows.
Contribution to the habit of hydrothermally grown corundum
Authors: Franke W. , Ghobarkar H. 
Published: July 2007

AbstractThe growth of corundum crystals without the influence of extraneous ions was achieved by the treatment of single crystals of topaz with supercritical water. The result is in agreement with previous calculations and considerations of other authors. A review of the different indexation of the corundum lattice is given.
Simple calculation of the axial temperature characteristics of a unidirectionally solidified sample
Authors: Vetter J. , Fruehauf J. , Schneider H. G. 
Published: July 2007

AbstractThe model described in this paper treats the numerical solution of a heat transfer problem in a one‐dimensional way determining the axial temperature characteristics. The physical quantities are considered as values depending on temperature and the real wall temperature profile of the heating‐cooling system is included. The sample shape corresponds to the numerous cases of long and thin cylinders. The calculation were carried out by a medium desk computer. The results of the calculation are in good line with the experimental data.
Forecasting future canadian residential heating demand: An illustration of forecasting with aggregated and disaggregated data
Authors: Berkowitz M. K. , Haines G. H. 
Published: July 2007

AbstractThis paper examines the sensitivity of forecasts to the level of aggregation of the data. A relative shares regression model and a multinominal logit model are tested with both aggregate and disaggregate survey data from 2109 respondents. The results indicate the appropriate model to use depends on whether the data are disaggregate or aggregate in form. Forecasts of solar heating of dwelling unit demand and market shares are also reported for Canada in terms of the solar price relative to the natural gas price and solar reliability relative to natural gas reliability.
Forecasting quality and information
Authors: Brockhoff Klaus 
Published: July 2007

AbstractIt is assumed that demand for information that subjectively appears to be relevant for forecasting improves forecasting quality. To study this hypothesis a number of forecasting experiments were conducted. Fifty managers from the housing business, from banking, and from a research institution were asked to forecast interest rates, using a Delphi process. They communicated via a computer system, and, to support their judgements, they had access to a data bank that was stored in the same system. Their communication with the system was automatically recorded. Part of the data collected in these experiments is used to study the existence of a relationship between information activities and forecasting results. A weak positive relationship is found if non‐linear functions are tested, where information demand is corrected by those data retrievals that seem to have resulted from an inability to handle the information system. For further research a more general, albeit less informative, Boolean model is suggested.
The use of growth curves in forecasting market development—a review and appraisal
Authors: Meade Nigel 
Published: July 2007

AbstractThe growth curves suitable for forecasting market development are identified and described. The underlying theoretical basis, if any, for their use is examined, and published examples of their applications are given. Doubt is cast on the value of long‐term forecasts derived from growth curves applied to markets for consumables. The problems of choice between competing curves are demonstrated by means of some examples. The requirements that a growth curve should meet in order to be an appropriate forecasting tool are identified and illustrated. Many of the published examples of growth curve use are shown to be vulnerable to criticism under one or more of these criteria.
Forecasting the price evolution of new electronic products
Authors: Dino Richard N. 
Published: July 2007

AbstractThis study tests the hypothesis that prices in new markets change in a pattern similar to and related to the product life cycle. Three stages of price decline have been identified in electronic product markets and can be associated with the introduction, take‐off and growth, and maturity stages of the product life cycle. The study integrates the methodologies of the product life cycle concept and experience curve theory and analyses price and product behaviour for radios, monochrome (black and white) televisions, colour televisions and video cassette recorders. The empirical evidence supports the hypothesis and suggests, as a general rule, that a better understanding of a product's life cycle and the factors that affect it can aid in the development of price forecasts. In fact, the marriage of experience curve theory and the product life cycle concept provides a methodology for quantifying the impact of influential factors and gives the analyst the ability to bound the uncertainty around price forecasts, ultimately leading to better strategic decisions, today, for tomorrow's markets.
Computing the variance of the forecast error for the holt‐winters seasonal models
Authors: Sweet Arnold L. 
Published: July 2007

AbstractThis paper presents expressions for the variance of the forecast error for arbitrary lead times for both the additive and multiplicative Holt‐Winters seasonal forecasting models. It is shown that even when the smoothing constants are chosen to have values between zero and one, when the period is greater than four, the variance may not be finite for some values of the smoothing constants. In addition, the regions where the variance becomes infinite are almost the same for both models. These results are of importance for practitioners, who may choose values for the smoothing constants arbitrarily, or by searching on the unit cube for values which minimize the sum of the squared errors when fitting the model to a data set. It is also shown that the variance of the forecast error for the multiplicative model is nonstationary and periodic.
Using the bootstrap to evaluate forecasting equations
Authors: Peters Stephen C. , Freedman David A. 
Published: July 2007

AbstractThe bootstrap, like the jack‐knife, is a technique for estimating standard errors. The idea is to use Monte Carlo simulation, based on a non‐parametric estimate of the underlying error distribution. The bootstrap will be applied to an econometric equation describing the demand for energy by industry, to determine multi‐period forecasting error and choose among competing specifications. The delta method for estimating forecast errors turns out to be too optimistic by a factor of 2.
Extraneous expert information
Authors: Clemen Robert T. 
Published: July 2007

AbstractWhen a Bayesian decision maker has to choose among information sources, he should consider the anticipated impact that the information will have on his posterior distribution. In some cases he may determine at the outset that an information source will have no effect on his posterior beliefs, no matter what that source says. Such an information source is called extraneous. In this paper we discuss Bayesian conditions for extraneous information sources, and show a hypothetical example involving experts with overlapping information. Analysis of U.S. weather forecasts demonstrates how this concept can be operationalized to test hypotheses concerning the use of information by forecasters.
A model of calibration for subjective probability distributions and its application to aggregation of judgements
Authors: Curtis Paula E. , Ferrell William R. , Solomon Ira 
Published: July 2007

AbstractA simple model is proposed of the statistical structure underlying the calibration of auditors' subjective probability distributions for account balances, and potentially for other unknown quantities. The model relates calibration curve shape to two parameters which represent over‐ or underconfidence and over‐ or underestimation. It is fitted to data from expert auditors. Different types of account appear to have different calibration characteristics. The model helps predict approximately the effects on calibration of aggregating individual subject distributions. Aggregation improves accuracy, but produces a strong tendency towards underconfidence. One aggregation method, predicting the best judgement in the group and using it as the group judgement, is found to be quite effective, much better than averaging the fractiles of individual distributions.
Beyond heuristics and biases: A contingency model of judgemental forecasting
Authors: Beach Lee Roy , Barnes Valerie E. , Christensen‐Szalanski Jay J. J. 
Published: July 2007

AbstractThe conflicting viewpoints about the quality of judgemental forecasts are examined and a model is proposed that attempts to resolve the conflict. The model sees forecasts as contingent upon the repertory of forecasting strategies that the forecaster brings to the forecasting task, the strategy that he or she selects as a function of the characteristics of the task, and the rigour with which he or she applies the strategy as a function of the motivating characteristics of the environment in which the task is encountered. The implications of differences in subjects' and experimenters' assumptions about which strategies are appropriate in experimental studies are examined, as are the implications of the differences between the motivating aspects of experimental and applied settings on both performance and on the generatizability of the results of experiments to applied judgemental forecasting.
A super‐resolution algorithm for spectral estimation and time series extrapolation
Authors: Moutter S. P. , Bodger P. S. , Gough P. T. 
Published: July 2007

AbstractRecent developments in the signal processing field of electrical engineering have resulted in several frequency domain methods of extrapolating a time series. Insight gained in testing one such method, the Papoulis algorithm, has been used to suggest modifications which greatly improve its performance under most operating conditions where real data are concerned.The modified Papoulis method thus developed has been applied to electricity load forecasting over the short and medium term, as well as to world economic and energy data, to assess the cyclic structure present in each series about a trend.
Expert judgments of political riskiness
Authors: Mumpower Jeryl L. , Livingston Steven , Lee Thomas J. 
Published: July 2007

AbstractProfessional analysts' judgments of the political riskiness of 49 focal countries for the period 1983‐1985 were studied. Data were collected on nine predictor variables; each was significantly correlated at the 0.01 level with ratings of political riskiness. The highest correlation was withinfant mortalityandlife expectancy; either accounted for roughly 50% of the variance in ratings. Different variables were better predictors of political risk within different geographic regions. A factor analysis suggested the presence of three underlying factors. The predictor variable with the highest loading was chosen to represent each of the three factors. These were:exchange rate differential; estimated inflation rate; andinfant mortality rate. Approximately 75% of the variance in ratings could be accounted for on the basis of a linear combination of the three predictor variables. These three variables were capable of good prediction even for various subsets of countries based on geographic region or other criteria. Using all nine variables as predictors resulted in only marginal improvement. A cluster analysis revealed little difference among clusters of judges. Ratings by undergraduate students closely paralled those of professional analysts. As in previous studies of expert predictions and forecasts, claims of expertise in political risk analysis were better supported by command of factual knowledge than by differentially superior predictive ability.
Comparing ex‐ante forecasts from a sem and var model: An application to the italian economy
Authors: Boero Gianna 
Published: July 2007

AbstractThe predictive performance of a large‐scale structural econometric model (SEM) of the Italian economy the Prometeia model is compared in this paper with a vector autoregressive (VAR) model estimated for a selection of six main variables of interest. The paper concentrates on the quarterly ex‐ante forecasts of GDP growth rate and the annual forecasts of GDP growth and inflation rate, over the period 1980‐85. It concludes that no forecaster is systematically better than the other. In particular, the VAR model outperforms the SEM in short‐run forecasts, suggesting that, for the latter, more careful attention should be addressed to questions of dynamic specification. On the other hand, for longer intervals, the SEM forecasts are more accurate than the VAR forecasts, in that they can benefit from the judgemental interventions of the model users and the model can pick up the non‐linearities of the economy which cannot be captured by the VAR. Given the different kinds of information that can be extracted from the two approaches, it seems more reasonable to consider them as complementary rather than alternative tools for modelling and forecasting. Therefore, rather than attempting to establish the superiority of one type of model over the other, this kind of comparisons should be seen as a useful diagnostic tool for detecting types of model misspecification.
Improved business planning through an awareness of political cycles
Authors: Young Peg , Marcus Lfred A. , Koot Ronald S. , Mevorach Baruch 
Published: July 2007

AbstractCan business planning be improved if more attention is paid to underlying political cycles? This paper compares practitioner and researcher perspectives on this issue. While practioners stand to gain useful insights from a careful examination of past political cycles, these insights may be disconfirmed by rigorous tests carried out by researchers. In this paper we isolate and examine five hypotheses from the literature on the political‐economic cycle.
Optimal selection of forecasts
Authors: Chen Lian , Anandalingam G. 
Published: July 2007

AbstractMany studies have shown that, in general, a combination of forecasts often outperforms the forecasts of a single model or expert. In this paper we postulate that obtaining forecasts is costly, and provide models for optimally selecting them. Based on normality assumptions, we derive a dynamic programming procedure for maximizing precision net of cost. We examine the solution for cases where the forecasters are independent, correlated and biased. We provide illustrative examples for each case.
Hydrological effects of changes in levels of atmospheric carbon dioxide
Authors: Wolock D. M. , Hornberger G. M. 
Published: July 2007

AbstractThe potential influence of increasing levels of atmospheric carbon dioxide (CO2 ) on water resources includes changes in evapotranspiration that result from control of stomatal resistance by CO2 and changes in precipitation and temperature caused by ‘greenhouse’ warming. In this study we investigate the potential effects of CO2 change on the hydrological response of a forested catchment in Shenandoah National Park, Virginia. Steady temporal trends are superimposed on stochastically derived time series of precipitation and temperature. These input data, which account for the natural variability of the system and the hypothetical effects of climate change, are then used to drive TOPMODEL, a variable‐source‐area hydrological model. A variety of climate‐change scenarios is simulated and temporal trends in annual average flow, peak flow, and basin yield are detected using Kendall's tau statistic. The direction and magnitude of the runoff trends are dependent on the relative magnitudes of the induced trends in precipitation, temperature, and stomatal resistance. Stochastic variability in temperature and precipitation obscure the runoff trends even when real trends in precipitation, temperature, and stomatal resistance are significant.
Is it possible to find an econometric law that works well in explanation and prediction? The case of Australian money demand
Authors: Swamy P. A. V. B. , Tavlas George S. 
Published: July 2007

AbstractPratt and Schlaifer's (1984, 1988) research employed in efforts to produce laws in economics are considered and their use in predicting future data is described. Data for Australia are used to illustrate the approaches.
Seasonality in large‐scale macroeconometric models
Authors: Fisher Paul G. , Wallis Kenneth F. 
Published: July 2007

AbstractMacroeconomic indicators are typically appraised in seasonally adjusted form, and forecasts are often presented in a similar way (as annual changes, for example). Moreover, the quarterly macroeconomic models used in forecasting are commonly estimated from seasonally adjusted data. Nevertheless, these models can generate forecasts with seasonal patterns, and this paper assesses the cause and cure of this phenomenon. It is found that forecast seasonality is induced by seasonality in the various inputs: exogenous variables, residual adjustments, the dynamic specification of certain equations, and annual changes in policy variables. Series changing annually but observed quarterly are termed ‘intercalated series’, and are simple examples of periodic processes. Forecast seasonality can be removed by appropriate adjustment of all these inputs. Models containing explicit future expectations variables solved in a model‐consistent manner are also considered: numerical sensitivity to the terminal quarter may result from terminal conditions that require adjustment when seasonality is present.
The real exchange rate, fiscal policy and the role of wealth an analysis of equilibrium in a monetary union
Authors: Barrell R. , In't Veld J. W. , Gurney A. 
Published: July 2007

AbstractThis paper is concerned with the adjustment processes within a potential European monetary union and looks in particular at permanent asymmetric shocks that require an adjustment in a country's (or region's) real exchange rate. We first consider some of the implications of EMU and the question of asymmetries within the European economy. The presence of asymmetries and, in particular, different institutional structures in labour markets is a potential source of tension within a union and it could make a union difficult to sustain. However, automatic adjustment processes will be at work within a monetary union as a result of changes in relative price levels, which change real exchange rates, and also as a result of changes in wealth stocks. We use our econometric world model, NIGEM, to investigate the effects of asymmetric fiscal expansions and real exchange rate misalignments within a monetary union. In order to quantify the effects of such permanent asymmetric shocks we have introduced wealth into our model. Our simulations suggest that the principal impact of the fiscal expansion on both output and the price level will occur within the country in which the expansion occurs. Short‐term gains are crowded out in the medium term, and while monetary union reduces crowding out in the short term, it increases the rate at which crowding out occurs thereafter. We also analyse the effects of real exchange rate misalignments and find that the processes of adjustment may be very protracted. This could cause strain on the union as adjustment costs are shared unequally.
Simulating the European economies under alternative monetary policy assumptions
Authors: Richardson Pete 
Published: July 2007

AbstractThis paper examines the implications of alternative monetary policy rules for economic stabilization within Europe, using the OECD world model, INTERLINK. The results suggest that policy linkage through the Exchange Rate Mechanism will have differing effects on the effectiveness of stabilization policies depending on the nature of economic shocks. For demand shocks, the choice of monetary rule in the country of the ‘anchor’ currency is of more consequence than the flexibility of exchange rates. For supply shocks, exchange rate rigidity is likely to have more problematic effects on economic adjustment. Spillover effects are also important when the shock is felt primarily by the ‘anchor’ economy.
Comparative simulation analysis of the European multi‐country models
Authors: Whitley John D. 
Published: July 2007

AbstractThis paper is a product of the SPES programme on multi‐country models and describes a set of diagnostic simulations on five European‐based multi‐country models. These are the EEC's model QUEST as operated by the Deutsches Institut fur Wirtschaftsforschung (DIW); the GEM model jointly operated by the National Institute of Economic and Social Research and the London Business School; the Oxford Economic Forecasting model; the MIMOSA model used by the Observatoire Francais des Conjonctures Economiques (OFCE) and Centre D'Etudes Prospectives et D'Informations Internationales (CEPII), and OECD's Interlink model. The simulation experiments are designed to clarify the interdependencies and relative structures of the major European economies using both (internal) single‐country and external common shocks.All the models tend to adopt similar specifications across the different countries but differences in simulation responses still occur and cross‐model differences often dominate those between countries. Several general qualitative conclusions can be drawn, however. For example, independent fiscal policy under a monetary policy of fixed real interest rates has only limited power to raise output, although full crowding out does not occur. Spillover effects to the other European economies are weak with respect to independent fiscal expansions but stronger for an external shock.The model comparisons reveal differences in modelling strategies, notably with respect to the treatment of inflation on consumption, the role of activity on import behaviour and the influence of excess demand on wages. These; are all key factors in explaining simulation differences between the models. Not all the models currently have endogenous exchange rate determination and this becomes an essential requirement for analysis of non‐EMS and EMS‐style regimes.