bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation process in a cast alloy Al‐3.5 wt.pct Zn‐4 wt.pct Mg
Authors: Dzuong Lecong 
Published: July 2007

AbstractThe structural changes during ageing of an alloy containing 3.5 wt.pct Zn and 4 wt.pct Mg were studied by means of transmission electron microscopy. It was shown that the precipitation process in this alloy differs from that in the alloys having high Zn/Mg ratios. The following phases were observed: hexagonal transition T′ phase, cubic stable T phase, hexagonal transition β′ phase, cubic stable β phase and hexagonal transition β′ phase. The precipitation process proposed the formation of two kinds of clusters in the beginning, i.e. Zn‐rich and Mg‐rich clusters. The former gradually transforms into GP zones and then into the T′ and T phases. The latter transforms into the β′ and β phases. The existence of the β′ phase seems to be a result of the segregation of the solute elements in the cast alloy.
Real structure investigations of LiNbO3 single crystals grown by the flux method
Authors: Hemmerling J. , Hergt R. 
Published: July 2007

AbstractThe real structure of flux grown LiNbO3 crystals is investigated by etching technique, X‐ray topography, and optical polariscopic method. The main defects are microdomains, dislocations and minor impurities of V3+−ions. The crystals do not contain growth striations. The mean dislocation density is in the order of 103 cm−2. The main origin of the defects seems to be post‐growth mechanical stress. The results are discussed in comparison to the real structure typically found in the case of Czochralski crystals.
Experimental proof on an anisotropic anharmonic DEBYE‐WALLER factor for silver
Authors: Vega H. , Försterling G. , Kleinstück K. 
Published: July 2007

AbstractOn silver were done high‐precise measurements of the thermal dependence of integrated intensities of coherently scattered X‐ray radiation. The experimental results attained at the low temperature range (80–286) K agree with calculations according to the model of the lattice vibrations suggested by WILLIS (1969) which bases on anharmonicity and anisotropy of the lokal potential. An anisotropic anharmonic DEBYE‐WALLER factor of silver was detected on this basis. The measurements at the temperature range close to and above room temperature to 1150 K didn't yield any significant confirmation of the model.
Perspective fields of application of texture topography and further development of its apparatus
Authors: Born E. , Schwarzbauer H. 
Published: July 2007

AbstractThe applications of a new X‐ray topography method designed for investigations of polycrystalline samples are closely related to reasons of different X‐ray reflectivity from point to point in the surface of the specimen. The discussion of these relationships is followed by suggestions for an apparatus. The most simple one is based on the principle of the “camera obscura” locating the diaphragm of the camera at the place where a diffracted beam is focussed either according to the focussing principle of Guinier or according to Bragg‐Brentano, respectively.
Modifications test of vacuum deposition Ni/Cr films with Mn and Si for thin film resistors
Authors: Schippel E. 
Published: July 2007

AbstractFor producing Ni/Cr thin film resistors an Si addition would be especially suitable to reduce the TCR, as Si forms several phases with Ni and Cr. By evaporating powder mixtures deposition thin films were produced with constant Cr portions of 20 at.%, 30 at.% and 40 at.% and from 5 to 50 at.% Si or Mn, rest Ni. Whereas the layers containing Mn have an exclusively positive TCR, there is a shift to negative TCR in the layers containing much Si.
Topographic studies of an X‐ray interferometer of czochralski‐silicon
Authors: Dietrich B. , Kittner R. , Zaumseil P. , Grosswig S. 
Published: July 2007

AbstractContrary values of lattice deformation result from X‐ray Moiré pattern and from reflection topographs in a double crystal diffractometer. An explanation is presented on the base of lattice deformations which vary only in the direction of growth of the crystal.
Growth of bulk zinc chalcogenide single crystals from the vapour phase and their use for laser screens of projection colour television
Authors: Bulakh B. M. , Kozlovsky V. I. , Moiseeva N. K. , Nasibov A. S. , Pekar G. S. , Reznikov P. V. 
Published: July 2007

AbstractResults on ZnSe, ZnSexS1−x and ZnS crystal growing from the vapour phase up to 7.5 cm3 in volume are described. Crystals were grown on sapphire, ZnS, ZnSexS1−x and quartz glass substrates without a contact of the growing crystal with a growth ampoule and using the molten tin as a heating medium. Large high‐purity crystals with a density of etch pits of 103 cm−2 were obtained They exhibited an effective exciton luminescence and rather high radiation efficiency (30 ± 10% for ZnSe at T = 77 K). This made it possible to use these crystals for fabricating laser screens for a cathode ray tube. The main laser parameters obtained on a ZnSe screen at T = 80 and 300 K using a 75 keV electron beam excitation are presented. The light power output reached 0.8 W at T = 80 K; this allowed to obtain a 10 cd · m−2 TV image of 1.5 × 2 m2 in area.
The comparison of the properties of hydrogen forms of zeolite T obtained by the treatment with hydrochloric acid af 100 °C or through the ammonium form and its decompostion
Authors: Cichocki A. 
Published: July 2007

AbstractThe modification of zeolite T through the ammonium form and its decomposition is in comparison with the treatment with hydrochloric acid, more effective and more selective for the obtainment of hydrogen forms with high decationization degree at low dealumination. The calcination at 500 °C introduced between the treatments of zeolite with acid allows for the stabilization of the structure and enlargement of the H+/K+ exchange.
Growth kinetics, habit modifications and surface designs of lead iodide grown by the new gel technique
Authors: Abdulkhadar M. , Ittyachan M. A. 
Published: July 2007

AbstractLead iodide crystals have been grown in silica gel by the new gel technique by the inter action between colloidal lead tartrate and KI solution. The crystals are found to exhibit interesting surface designs. Growth kinetics and habit modifications of the crystal have been investigated. Two dimensional surface nucleation and screw dislocation are found to partake in the growth process of the crystals.
Photo‐EPR of deformation‐produced defects in GaAs
Authors: Wosiński T. 
Published: July 2007

AbstractDeformation‐produced paramagnetic centres have been studied in GaAs crystals uniaxially compressed at 400° using EPR technique (X band). The effect of light with photon energies from 0.4 to 1.5 eV on the populations of the centres has been investigated. On the basis of the experimental results a model is proposed which locates the energy levels of two of the centres at Ec − 1.05 eV and Ev + 0.75 eV.
Distribution coefficient of foreign ions in ionic crystals‐A function of the ionic radius
Authors: Bollmann W. 
Published: July 2007

AbstractThe distribution coefficient k of foreign ions in melt‐grown crystals is found to be proportional to R−B and R+B in the case of large and small ionic radii R, respectively. As to alkali halides and alkaline‐earth fluorides the exponent B corresponds to the number of nearest neighboured or charge‐compensator ion sites in the case of homovalent and heterovalent foreign ions, respectively.
Polytypism of kaolinite‐type minerals: An aid to visualize the stacking of layers
Authors: Ďurovič S. , Mikloš D. , Dornberger‐Schiff K. 
Published: July 2007

AbstractA model consisting of 3 transparent sheets, moveable one relative to the other, is used to obtain pictorial representations of any of the 36 positions which one dioctahedral (mesooctahedral) kaolinite layer may occupy relative to its predecessor. In a similar manner such a model may be used to represent the corresponding 10 possible positions of any trioctahedral (homo‐octahedral) kaolinite layer relative to its predecessor. The model is based on the discussion of these possibilities in terms of OD theory which is given in outline.
The dissolution and crystallisation of amphoteric metal hydroxides from sodium hydroxide solutions: Ionic equilibria, crystalline phases and crystallisation mechanisms
Authors: Packter A. , Dhillon H. S. 
Published: July 2007

AbstractThe dissolution and recrystallisation of beryllium, zinc, cadmium and tin (II) hydroxides and chromium (III), iron(III), aluminium, scandium, yttrium, gallium and indium hydroxides, from sodium hydroxide solutions of concentrations C = 1 to 20 M at ambient temperatures, are surveyed. The different inic equilibria in metal hydroxide‐sodium hydroxide systems are examined: the phases crystallising from different sodium hydroxide solutions are tabulated and crystallisation mechanisms are analysed.
Estimation of the Debye temperature of diamond‐like semiconducting compounds by means of the Lindemann rule
Authors: Deus P. , Schneider H. A. , Voland U. 
Published: July 2007

AbstractApplication of the Lindemann rule to the estimation of the Debye temperature θ of diamond like semiconducting compounds is discussed. The classical formula of LINDEMANN was modified by a constant K2: θ = K1 \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {T_{\rm m} /A \cdot v^{2/3} } + K_2 $\end{document} + K2. The constants K1 and K2 are given for AIIIBV, AIIBVI, AIIBIVC2V and AIBIIIC2VI compounds. These were calculated as well from X‐ray diffraction data as from θ evaluated from specific heat capacity and elastic constants.
Etch‐ and Transmission Electron Microscope Investigations of Microdefects in (001) LEC‐GaP Substrates
Authors: Gottschalch V. , Wagner G. , Pasemann M. 
Published: July 2007

AbstractThe etch pattern of (001) and (110) LEC‐GaP doped with sulphur (NDNA in the range from 3–7 × 1017 cm−3) do not only show dislocation etch pits but fine pits, so‐called “saucer pits” (S‐pits). The distribution of S‐pits, their etching behaviour and transmission electron microscope observations of etched samples indicated a clear correlation between S‐pits and microdefects (fauted‐, prismatic dislocation loops and precipitates).
Studies on twin boundaries in calcite crystals
Authors: Desai C. C. 
Published: July 2007

AbstractNatural single crystals of calcite have been cleaved along (100) planes and cleavage faces have been etched in 2% and 3% citric acid solutions. Etching produces twin boundaries oriented in 〈010〉 directions. The etch pits on the two sides of the twin boundary are oppositely oriented. It has been conjectured that the rows of pits might have been formed due to etching of dislocations on twin boundaries. One to one correspondence of twin boundaries has been established on matched cleavage faces. This is further confirmed by studying the induced twin regions produced on a (100) cleavage plane by indenting that plane itself. The implications are discussed.
Auger electron spectroscopic studies of the water vapour adsorption on the (100) surface of austenitic chromium‐nickel steel
Authors: Uhilmann K. , Haupold G. , Müssig H.‐J. , Storbeck F. 
Published: July 2007

AbstractThe water vapour adsorption on the (100) surface of chromium‐nickel steel was studied by Auger electron spectroscopy (AES) in the temperature range of 300 K to 700 K at water vapour pressures of 13.3 μPa to 133 mPa. The water vapour adsorption goes on more slowly than the oxygen adsorption under the same conditions. The measured kinetic isotherms may be described by logarithmic time laws as they are typical of the adsorption on inhomogeneous surfaces. With rising temperature of the samples the rate of adsorption as well as the quantity of fragments of the water molecule adsorbed during saturation state increases, i.e. the adsorption is activated. By means of the measured adsorption isotherms it may be concluded that a dissociative adsorption takes place.
Fitting of growth curves over time when the data are obtained from a single realization
Authors: Wiorkowski John J. 
Published: July 2007

AbstractThis paper focuses on the general problem of forecasting the maximum value of a time series which by the nature of the data must approach an asymptotic value. Examples of such series include the growth of organisms, the concentration of a chemical reagent during a reaction occurring over time or the amount of a fossil fuel resource which has been discovered or produced as a function of time. The approach taken below differs from the usual models for this type of data in that it assumes that an unobserved time series is actually driving the process, and that the observed data series is a function of the unobserved process. In the case of fossil fuels the unobserved series might be a measure of the exploratory drilling, the number of production days in a given time period or even the amount of fiscal resources devoted to exploratory activities. A maximum likelihood method is developed for estimating the parameters of the process, especially the maximum S, and the covariance structure of the estimators is developed. The methodology is illustrated on an example of oil production. Finally, methods are developed for forecasting the data into the near future.
Combination of forecasts in electricity demand prediction
Authors: Smith D. G. C. 
Published: July 2007

AbstractAccurate demand prediction is of great importance in the electricity supply industry. Electricity cannot be stored, and generating plant must be scheduled well in advance to meet future demand. Up to now, where online information about external conditions is unavailable, time series methods on the historical demand series have been used for short‐term demand prediction. These have drawbacks, both in their sensitivity to changing weather conditions and in their poor modelling of the daily/weekly business cycles. To overcome these problems a framework has been constructed whereby forecasts from different prediction methods and different forecasting origins can be selected and combined, solely on the basis of recent forecasting performance, with no a priori assumptions of demand behaviour. This added flexibility in univariate forecasting provides a significant improvement in prediction accuracy.
Forecasting the Antwerp maritime steel traffic flow: A case study
Authors: de Gooijer Jan G. , Klein Andre 
Published: July 2007

AbstractThis paper uses multivariate time series models to specify the maritime steel traffic flow in the port of Antwerp. The time series considered are the total outgoing and total incoming maritime steel traffic and the total steel production in the EEC. The obtained time series models provide useful insight into the general behaviour of the maritime steel traffic flow during the period 1971–82. In particular, they provide a quantitative interpretation of important changes which took place in the European steel industry during that period. The multivariate time series models produce forecasts which are a substantial improvement over those obtained by univariate time series models. This is especially the case for the series of total incoming maritime steel traffic in the port of Antwerp, when differencing and transformation of the original data are applied.
Quality/value relationships for imperfect weather forecasts in a prototype multistage decision‐making model
Authors: Katz Richard W. , Murphy Allan H. 
Published: July 2007

AbstractSome theoretical results concerning the nature of the relationship between the scientific quality and economic value of imperfect weather forecasts are obtained. A prototype multistage decision‐making model is considered, involving only two possible actions and two possible states of weather. This particular form of model is motivated by a real‐world application known as the fruit‐frost problem. For an infinite‐horizon, discounted version of this model it is shown that economic value remains zero below a forecast quality threshold and then rises monotonically but nonlinearly above this threshold. In particular, the relative sensitivity of economic value to changes in the quality of forecasts increases as perfect information is approached. This curve is compared with quality/value relationships that have been obtained for other versions of the model; namely, a single‐stage model and a multistage, finite‐horizon model.
Robust estimation of level and trend
Authors: Ferelli Mario , Wilson G. Tunnicliffe 
Published: July 2007

AbstractNumerical state space models are efficiently implemented for the estimation of the underlying level and trend of a time series. The model specification is chosen so that the estimation is insensitive to outliers yet adapts rapidly to step changes in level. An example illustrates, by means of projection plots, how at times of uncertainty in the evolution of the series the inferred distribution of level and trend may be multi‐modal.
Transformations and dynamic linear models
Authors: Lenk Peter J. , Tsai Chih‐Ling 
Published: July 2007

AbstractThe dynamic linear model (DLM) with additive Gaussian errors provides a useful statistical tool that is easily implemented because of the simplicity of updating a normal model that has a natural conjugate prior. If the model is not linear or if it does not have additive Gaussian errors, then numerical methods are usually required to update the distributions of the unknown parameters. If the dimension of the parameter space is small, numerical methods are feasible. However, as the number of unknown parameters increases, the numerial methods rapidly grow in complexity and cost. This article addresses the situation where a state dependent transformation of the observations follows the DLM, buta priorithe appropriate transformation is not known. The Box‐Cox family, which is indexed by a single parameter, illustrates the methodology. A prior distribution is constructed over a grid of points for the transformation parameter. For each value of the grid the relevant parameter esitmates and forecasts are obtained for the transformed series. These quantities are then integrated by the current distribution of the transformation parameter. When a new observation becomes available, parallel Kalman filters are used to update the distributions of the unknown parameters and to compute the likelihood of the transformation parameter at each grid point. The distribution of the transformation parameter is then updated.
Merging monthly and quarterly forecasts: Experience with mqem
Authors: Howrey E. Philip , Hymans Saul H. , Donihue Michael R. 
Published: July 2007

AbstractForecasts from quarterly econometric models are typically revised on a monthly basis to reflect the information in current economic data. The revision process usually involves setting targets for the quarterly values of endogenous variables for which monthly observations are available and then altering the intercept terms in the quarterly forecasting model to achieve the target values. A formal statistical approach to the use of monthly data to update quarterly forecasts is described and the procedure is applied to the Michigan Quarterly Econometric Model of the US Economy. The procedure is evaluated in terms of both ex post and ex ante forecasting performance. The ex ante results for 1986 and 1987 indicate that the method is quite promising. With a few notable exceptions, the formal procedure produces forecasts of GNP growth that are very close to the published ex ante forecasts.
Automatic arima modelling by the cartesian search algorithm
Authors: Höglund Rune , Östermark Ralf 
Published: July 2007

AbstractIn the present study we report on the development and test results of a Cartesian ARIMA Search Algorithm, designed for automatic generation of univariate models for time series data within specified parameter intervals of the identification and estimation stages. Model retention is determined within a preselected set of statistics. By interpreting these statistics as dimensions of the constructed criterion space, we obtain a subset of non‐dominated models according to the rule of maximum dispersion over the efficient set. The CARIMA algorithm allows free specification of the number of criteria used in the runs. The algorithm was tested with both simulated and real economic data. The results based on simulated data indicate that the precision of the CARIMA algorithm is lower for seasonal models and higher for non‐seasonal ones, thus suggesting an inverse relationship between algorithm performance and model complexity.
Dynamic relationship analysis of us gasoline and crude oil prices
Authors: Liu Lon‐Mu 
Published: July 2007

AbstractThis paper studies the dynamic relationships between US gasoline prices, crude oil prices, and the stock of gasoline. Using monthly data between January 1973 and December 1987, we find that the US gasoline price is mainly influenced by the price of crude oil. The stock of gasoline has little or no influence on the price of gasoline during the period before the second energy crisis, and seems to have some influence during the period after. We also find that the dynamic relationship between the prices of gasoline and crude oil changes over time, shifting from a longer lag response to a shorter lag response. Box‐Jenkins ARIMA and transfer function models are employed in this study. These models are estimated using estimation procedure with and without outlier adjustment. For model estimation with outlier adjustment, an iterative procedure for the joint estimation of model parameters and outlier effects is employed. The forecasting performance of these models is carefully examined. For the purpose of illustration, we also analyze these time series using classical white‐noise regression models. The results show the importance of using appropriate time‐series methods in modeling and forecasting when the data are serially correlated. This paper also demonstrates the problems of time‐series modeling when outliers are present.
A bayesian forecasting model for sequential bidding
Authors: Attwell D. N. , Smith J. Q. 
Published: July 2007

AbstractIn this paper we consider the problem facing a company in selecting the values of bids to submit on a sequence of contracts put out to tender. A simple‐to‐implement Bayesian forecasting model is presented, based on a steady Dirichlet process whose states are indexed by the possible bid decisions open to the company. The model gives an explicit algorithm for calculating the state probabilities, needing only data on the lowest bid made by the company's competitors. The flexibility of the basic model makes it a potentially powerful forecasting system for use by companies bidding for contracts.
Using the bootstrap for improved ARIMA model identification
Authors: Aczel Amir D. , Josephy Norman H. 
Published: July 2007

AbstractThis paper presents a new method of identifying ARIMA time‐series models. We use the bootstrap technique in estimating the distribution of sample autocorrelations both separately and in a simultaneous inference setting. The bootstrap has the advantage of being nonparametric and thus free of reliance on asymptotic normality, which may not hold for short or medium‐size series. The simultaneous procedure is unique, as it has no feasible parametric alternatives. An application to exchange rates illustrates our methodology. In the example chosen, we are able to produce better forecasts using the model identified via the bootstrap technique.