bluuebunny/crossref_metadata_2025 huggingface dataset:
The defects in Se‐doped InSb single crystals
Authors: Prihodjko E. N. , Olhovikova T. J. , Hashimov F. R. , Dashevski M. Ja. , Molodtsova E. V.
Published: July 2007

Using optical microscopy and TEM methods as well as X‐ray topography method structural perfection of Czochralski grown Se‐doped InSb single crystals has been investigated. Se concentration was determined by mass‐spectrometry method and was in the range of 1.1017 to 9.1019 cm−3. – It has been shown that Se presence up to the highest concentration does not influence crystal dislocation structure, but gives rise to the large number of precipitates showing moiré contrast. The size of the precipitates is in the range of 0.5 μm to 3.8 μm. From the calculation of the contrast it has been grown that lattice parameter of the precipitates differs from that of matrix by 0.02 ÷ 0.05 Å. – Besides, in crystals with high Se concentration (9.1019 cm−3) small particles with symmetrical field of deformation appear.
Quantitative X‐ray diffraction analysis of textured sheet metals
Authors: Kämpfe B. , Patzelt P. , Nestler C.‐G.
Published: July 2007

A disadvantage of the quantitative X‐ray diffraction analysis of samples from sheet metals is the incorrectness of the measuring results owing to the presence of textures in the material. In considering several reflexes of every phase the influence of textures may be reduced. Such a method will be presented and tested. The yielded results show that the new method can be useful for textured sheet metal samples.
Oriented action of some solid substrates to liquid crystal layer
Authors: Derzhanski A. , Komitov L. , Mihailov M.
Published: July 2007

The orienting action of three types of layers on liquid crystal is investigated. Homogeneous orientation of the liquid crystal layer is obtained under the action of a transparent conductive SnO2 film and carbon film. Such an orientation is achieved with gelatin films as well. Homeotropic orientation of the liquid crystal can be also obtained by exposing the latter to ion bombardment with Ar ions.
Recent developments in the understanding of the structure and properties of grain boundaries in metals
Authors: Gleiter H.
Published: July 2007

The basic physical problems of the geometric models and structural models of grain boundaries based on computer simulations are considered. By comparing the approximations made in these models with the general solution of the problem based on the theory of metallic cohesion, we are led to conclude that

geometric grain boundary models (coincidence models) may be used to derive certain geometric features of a boundary (e.g. the boundary periodicity). However, due to the fact that interatomic forces are neglected, it seems not possible to deduce the actual atomic structure and properties of grain boundaries on the basis of these models.

Dislocation models of grain boundaries seem to be of physical significance only for low energy boundaries. In all other boundaries, misfit dislocation are theoretically and experimentally found to be delocalized in the sense that their core is smeared out in the plane of the boundary.

Structural boundary models deduced by computing the minimum energy atomic configuration using pairwise interatomic potential functions seem to represent a reasonable approximation of the actual atomic structure.

The experimental and theoretical evidence presented indicates that grain boundary properties can, in general, not be derived from computer models, as these properties depend partially on electronic effects.

Further developments of the physical understanding of grain boundaries seems to require the incorporation of electronic effects in the theory of interfaces.
Die Diffusion von Wasserstoff in Nickel‐Ein‐ und ‐Polykristallen bei 60°C
Authors: Gardavská G. , Lejček P.
Published: July 2007

Die Wasserstoffdiffusion in Ein‐ und Polykristallen von Nickel wurde mit dem Ziel untersucht, den Einfluß der Korngrenzen zu ermitteln. Es wird gefunden, daß die geringen Unterschiede in den Diffusionskoeffizienten sich nicht eindeutig auf die Unterschiede zwischen den polykristallinen Materialien und den Einkristallen zurückführen lassen. Die Korngrenzen beeinflussen den Mechanismus der Diffusion nicht wesentlich.
On the theory of normal growth of crystals in binary systems
Authors: Zelenev Yu. V. , Baikov Yu. A. , Molotkov A. P.
Published: July 2007

Crystallization processes of binary systems are considered, in which solid particles consisting of components A and B grow from the melt in monolayers of a two‐phase boundary zone by a mechanism of spontaneous thermal equilibrium type concentration fluctuations. The calculation is based on probability distribution functions. The region of small supercoolings of the binary system melt‐crystal proves most valid for this investigation. The change of the mean crystallization rate of the two‐phase boundary zone with the supercooling of the melt shows a linear behaviour. The dependence of the kinetic coefficient on the degree of the atomic roughness of the phase boundary with different numbers of monolayers in the phase boundary, the total number of particles in each monolayer, and a certain roughness are connected with the energy of positional disorder in binary systems.
Kristallstrukturänderungen des Magnesiumnitrats‐Hexahydrats, die infolge isodimorpher Substitution durch Co(II)‐ und Ni(II)‐Ionen entstehen
Authors: Balarew Chr. , Barkov D.
Published: July 2007

Mit Hilfe der Methode der physikalisch‐chemischen Analyse werden die Systeme Mg(NO3)2Co(NO3)2H2O und Mg(NO3)2Ni(NO3)2H2O bei 25,0°C untersucht. Es wird festgestellt, daß als Folge isodimorpher Substitution der Mg2+‐Ionen von den Mg(NO3)2 · 6 H2O‐Kristallen durch Co2+ oder Ni2+‐Ionen oberhalb einer bestimmten Substitutionsgrenze Strukturänderungen entstehen.
Solid‐phase growth of CuGaS2 crystals
Authors: Paorici C. , Zanotti L.
Published: July 2007

Homogenized mixtures of copper, gallium, and sulphur were annealed for 200 hrs. under vacuum at about 1000–1050°C (i.e. below the melting point of the CuGaS2 phase) in quartz ampoules in a vertical position, and then cooled down in a temperature gradient. The final charge was made up of three well‐defined portions: a yellow polycrystalline CuGaS2 with large blocks of CuGaS2 (close to stoichiometry), a black portion with darkgreen aggregates of small CuGaS2 crystals, and yellow laminae of CuGaS2 single crystals, slightly inclined away from [112] direction. — A coupled growth mechanism — solidstate‐diffusion‐assisted coalescence/vapour transport — is assumed.
Einfluß des Ionenbeschusses auf die Oberflächenstruktur von Kristallen aus Natriumchlorid
Authors: Marinov M.
Published: July 2007

Mittels elektronenmikroskopischer Untersuchungen werden die an der Oberfläche von Natriumchloridkristallen bei Ionenbeschuß auftretenden Strukturveränderungen verfolgt. An der Kristalloberfläche entstehen nach dem Beschuß Gebilde von Rundsymmetrie, deren Abmessungen mit der Zeit und der Stärke des Ionenbeschusses wachsen. Dabei werden die Grenzstrukturen der gebildeten Zonen von einer bestimmten Größe ab wie bei Wachstumsfiguren gröber.

Für die Untersuchung der feinen Mikrostruktur der Kristalloberfläche vor und nach dem Ionenbeschuß wird die Golddekorationsmethode unter gleichzeitigem Ionenbeschuß angewendet. Es wurde festgestellt, daß die Dichte und Größe der kleinen Goldkristalle in den aktiven Stellen sich von denen des übrigen Oberflächenteils unterscheiden.

Die Beurteilung des Bildungsmechanismus der runden Zonen erfolgt im Sinne der Darlegungen von Kaminski und Wehner über den Charakter des Zusammenstoßes zwischen den Ionen und Bauelementen des Kristallgitters.
Preferred Growth Direction of Ni Single Crystals by the Floating‐Zone Method
Authors: Hayashi S. , Komatsu H.
Published: July 2007

In Ni single crystals grown by the floating‐zone method, it was found that their growth directions tended to concentrate towards the 〈111〉 or the 〈100〉 direction. An interpretation was put forward for the preferred direction of these crystals in terms of thermal stability of the crystallographic planes in the solid‐liquid interface.
Structural Etching of {001} and {110} Faces of Various AIIIBV Compounds
Authors: Gottschalch V.
Published: July 2007

The present paper discusses the use of selective photoetching with H3PO4:H2O2 for characterizing various AIIIBV compounds and detecting misfit dislocations in transition layers. For GaP, the results obtained are compared with those realized with the use of an AB etchant for which suitable conditions for the structural etching of {001} material and the characterization of cleavage faces are given. The direction of the dislocation line is inferred from the shape and orientation of etch pits. The etch figures of different types of misfit dislocations are discussed.
The Molecular and Crystal Structure of 1 Ref, 3trans‐bis(4‐chloro‐phenyl)‐2trans‐nitro‐5‐oxoperhydropyrazolo[1,2‐a] pyrazol, a “non‐cisoid” 1,3‐Dipol Adduct
Authors: Kutschabsky L. , Dorn H.
Published: July 2007

The three‐dimensional structure of the title compound has been established by means of an X‐ray analysis. The product was formed by a thermal 1,3‐dipolar cycloaddition. According to the concerted [π4s + π2s]‐mechanism the formation of this stereoisomer should actually be forbidden. The structure determined by X‐ray analysis confirms the chemical results.
Electron Beam‐Specimen‐Environment Interactions in the HVEM
Authors: Butler E. P. , Goringe M. J.
Published: July 2007

Possible interactions between the electron beam, specimen and environment surrounding the specimen are categorised and discussed. A number of examples which illustrate the possible of such interactions on the results of an in‐situ experiment are given, and the importance of accurate knowledge of the environment is stressed.
Relation between the Activation Parameters of the Plastic Deformation in MgO Crystals Determined by Macroscopic and by In‐situ HVEM Experiments
Authors: Bartsch M. , Messerschmidt U. , Appel F.
Published: July 2007

The results of macroscopic strain rate and temperature cycling tests on MgO single crystals are compared with the results of in‐situ deformation tests in a HVEM on the basis of the basis of the thermally activated dislocation glide model. The activation volume estimated by strain rate cycling tests is compatible with the mean obstacle distance of the screw dislocations. However, the local stress estimated by in‐situ deformation tests was found to be larger than the macroscopic yield stress.
HVEM Study of the Development of the Recrystallization Texture in Deformed Copper Single Crystals
Authors: Wilbrandt P.‐J. , Haasen P.
Published: July 2007

〈110〉‐orientated single crystals of high purity copper were deformed in tension up to 80% elongation. Sections of the deformed material were examined by HVEM before and after annealing in situ. Additional measurements by a texture goniometer confirmed and supplemented the metallographic results. The orientations of all recrystallized micrograins can be interpretated as the result of multiple annealing twinning. Since the grain boundary energy may be lowered by twinning the new orientations may be selected for this reason. These results can explain the recrystallization textures observed by X‐ray techniques.
OH− absorption in LiNbO3 crystals doped with iron
Authors: Agamalyan N. R. , Balasanyan R. N. , Harutunyan V. E. , Vartanyan E. S.
Published: July 2007

On the basis of spectral and ESR investigations of crystals annealed in hydrogen, a mechanism of the formation of OH− absorption in crystals of lithium niobate doped with iron ions is suggested.
Quantum‐theoretical calculation of activation parameters for mass transfer and mass transport processes on ionic crystals (V)
Authors: Winzer A.
Published: July 2007

A report is given on the calculation of activation parameters for mass transfer and mass transport processes for ionic crystals on a quantum‐theoretical basis. Einstein's model for calculating the internal energy of ionic crystals and the specific heat was extended and applied to the problems of mass transfer and transport, the frequency of the optical phonons and the characteristic oscillation frequencies of the crystals (Einstein frequency, Debye‐frequency) being employed for the calculation. The experimentally determined activation energies of the mass transfer and transport processes were compared with the values calculated on a quantum theoretical basis which resulted in good agreement.
Secondary nucleation and growth of magnesium sulphate heptahydrate in a fluidized bed
Authors: Karpiński P. H.
Published: July 2007

From both the theoretical and practical point of view, studies of secondary nucleation and crystal growth kinetics are of great importance, especially from point of view of varying hydrodynamic conditions. However, such a complex problem has not yet been solved. The present paper shows one of possible ways of approaching this problem using a fluidized bed crystallizer.
On the chemical transport of molybdenum dioxide with tellur tetrahalogens (II). The chemical transport of MoO2 with TeCl4 and TeJ4
Authors: Ritschel M. , Oppermann H.
Published: July 2007

A report is given on the transport behaviour of MoO2 with TeCl4 and TeJ4. Experimental and calculated transport rates are compared for the MoO2/TeCl4‐system. The influence of the various deposition conditions is described on the crystal habit of the MoO2‐monocrystals.
Microhardness investigations on potassium dihydrogen phosphate crystals
Authors: Joshi M. S. , Antony A. V. , Rao P. Mohan
Published: July 2007

Vickers microhardness measurements are carried out on single crystals of potassium dihydrogen phosphate. Dependence of hardness on indentation load and anisotropy in hardness of (100) and (011) planes are described. Crack patterns around indentation are found to be dependent on indenter orientation. Also explained are the fracture at high indentation load and etch patterns obtained on indented surfaces.
X‐ray investigation of NPOOB crystals
Authors: Przedmojski J. , Pura B.
Published: July 2007

Results of a series of experimental investigations by means of X‐rays of NPOOB crystals are reported. These results refer to the anisotropy of thermal expansion, to the smectic‐nematic phase transition and to critical scattering accompanying that phase transition. It is suggested that the smectic‐nematic phase transition is continuous.
Mechanoluminescence of halogenate crystals
Authors: Chandra B. P. , Verma R. D.
Published: July 2007

Mechanoluminescence (ML) has been studied in twenty halogenate crystals. All piezoelectric crystals show ML similar to the emission from second positive group of molecular nitrogen, and all the crystals not exhibiting ML are non‐piezoelectric. Some of the non‐piezoelectric crystals also exhibit nitrogen emission ML which is comparable in intensity to that of piezoelectric crystals. The ML appears only during the different steps developing in the fracture region of the force versus compression curve of the crystals. No considerable change in the ML activity is found due to the number of crystallization or due to the addition of different impurities from 100 to 10.00 ppm. The ML activity per mole of the halogenate crystals varies around four orders of magnitude. It is concluded that in addition to the piezoelectrification of the newly created surfaces there exists some other process of electrification which may cause the ML exitation in halogenate crystals.
Microhardness and structure of reactive ion‐plated chromium/carbon films
Authors: Bewilogua K. , Bugiel E. , Rau B. , Schürer C. , Weissmantel C.
Published: July 2007

Reactive ion‐plated chromium/carbon films exhibit a strong adherence and values of microhardness, which are clearly higher than those of pure chromium. Structure investigations by high resolution electron diffraction revealed microcrystallites of bcc Cr with mean diameters of some nm. In addition to chromium with a slightly dilated lattice, the films contain chromium oxide and chromium carbide. This interpretation is supported by the results of phase analysis with annealed Cr/C films.
Investigation of crystal lattice defects of PbZrO3 single crystals by transmission electron microscopy
Authors: Dobrikov A. A. , Presnyakova O. V.
Published: July 2007

The investigation of PbZrO3 single crystal structure was carried out by the method of transmission electron microscopy (TEM). It is shown that extended planar defects, slip lines, twins, and morié patterns are observed in PbZrO3.
The role of contamination layers in electron probe microanalysis
Authors: Wendt M.
Published: July 2007

After a brief description of the mechanism of the contamination layer build‐up the following topics are discussed: atomic number dependence of the contamination rate, composition of contamination layers, X‐ray intensity loss caused by a contamination layer, special problems in energy dispersive analysis, useful aspects of specimen contamination.
Orientation dependence of the NMR signal of deformed NaCl single crystals
Authors: Schlothauer K. , Berg G. , Fröhlich F.
Published: July 2007

The 23Na signal of different deformed NaCl crystals was measured as function of the angle of rotation of the crystal with respect to the static magnetic field. The second moment of the NMR line is changed periodically determined by the slip mechanism. It is shown that the measured second moment can be obtained by a superposition of the parts originating from two‐fold and four fold slip, respectively. The portion of the two slip mechanisms can be calculated quantitatively by fitting the experimental points.
Direct lifetime measurements in semiconductors with the scanning electron microscope (SEM)
Authors: Jakubowicz A.
Published: July 2007

This paper presents a new SEM technique for direct lifetime measurements. The Electron Beam Induced Current (EBIC) has been measured after removal of the electron beam in a SEM. The experiment has been performed for a silicon diode structure. A theoretical model has been given.
On the characterization of individual defects in silicon by EBIC
Authors: Kittler M. , Seifert W.
Published: July 2007

EBIC recombination‐contrast of defects is mainly caused by impurity atmospheres surrounding them. The contrasts for geometrically similar defects in samples having different diffusion lengths L > 100 μm are in proportion to the defect strengths .
Dislocation luminescence of germanium
Authors: Steinmann E. A.
Published: July 2007

The dependence of dislocation luminescence of p‐ and n‐Ge is investigated using different doping concentrations and ranges of pumping power. Three luminescence bands can be chosen. The main band (0.5 eV) is supposed to be due to the transition of the conduction band electron to the dangling bond, and is effective at any experimental conditions. Two other bands are rather sensitive to the dopant type. This enables us to suggest the model of the corresponding transitions in donor‐acceptor recombination terms.
Investigation of plasma interaction with carbon impurities on SiO2‐ and Al2O3 surfaces by EPR‐, Mass‐ and emission spectroscopy
Authors: Tiller H.‐J. , Breitbarth F.‐W. , Langguth B. , Göbel R. , Berg D. , Rudakoff G.
Published: July 2007

Carbon impurities on highly disperse SiO2 and Al2O3 are detected by their interaction with low pressure plasmas, with aid of mass‐, emission‐ and epr‐spectroscopic methods. The formation of surface defects on SiO2 by plasma treatment is strongly influenced by these impurities. Some of these defects are caused by the impurities also. These effects depend on the time of plasma interaction and on plasma gas, where Ar, O2, H2 and CO plasmas are investigated. By H2 plasma and the reaction products of the other mentioned above plasmas a partial hydrogenation of the carbon impurities is detected.
LiNbO3 layer growth in a LiVO3 high temperature solution
Authors: Hemmerling J. , Fischer K. , Sinn E.
Published: July 2007

Homoepitaxy of LiNbO3 takes a successful course in high temperature solutions (HTS) with LiVO3 as a solvent. In order to optimize the deposition process the phase correlations in the pseudobinary system LiNbO3‐LiVO3 were specified by means of DTA. At the liquidus temperatures the HTS with concentrations of 15 to 40 mole % have an approximately constant shear viscosity of η ≈ 13.5 mPa · s, similary to solvents containing lead compounds. Always smooth LPE‐layers grow on singular {1102}‐substrates. Surfaces of all other orientations were found to be rough because rhomboedric faces of LiNbO3 form in the stable state. On the negative polarized (0001)‐face epitaxy is still possible, however, on the opposite (0001)‐face only a hexagonal cellular structure is observed because the singular faces develop, exclusively.
Structure and electrical resistance of thin scandium films (III). Study on electrical properties
Authors: Loboda V. B. , Protsenko I. E.
Published: July 2007

The specific resistance‐thickness of ScHx (vacuum 10−5 to 5 · 10−6 Torr) and Sc films (vacuum 1 · 10−8 to 3 · 10−8 Torr) relationships have been obtained by keeping a record of a film resistance directly in the course of condensation. The results are discussed according to the theory FUCHS‐SONDHEIMER (ScHx, Sc) and MAYADAS‐SHATZKES (Sc) assuming a diffuse scattering of the carriers (P = 0) on the external surface of the films. A mean free path of the current carriers is 188 to 355 Å (T ⋍ 300 K) for ScHx and 400 Å with grain‐boundary scattering parameter from 0.1 to 0.3 for Sc. The temperature dependence of specific resistivity of Sc films was obtained in the interval from 300 to 650 K during the annealing in vacuum 5 · 10−9 Torr.
Determination of refractive indexes of dielectric films by the use of immersion liquids
Authors: Ayupov B. M. , Sysoeva N. P.
Published: July 2007

Examples of using immersion liquids in ellilipsometry and multiple‐beam interferometry are given. The refractive index of very thin (∼ 5.0 nm) silica films on silicon and on films of silicon nitride are determined by the ellipsometry method. The method of precise determination of refractive index of monolayer dielectric films is described when a precision equal to ± 3 · 10−4 was reached. A method of determination film thicknesses near the substrate surface in a twolayer system is suggested. The construction of different prisms is given by means of which the immersion liquids are inserted. The selection of the equations for the determination of refractive index in the multiple‐beam interferometry is discussed. Two versions of the use of immersion liquids for the determination of refractive indexes of dielectric films by interferometry method are given.
Influence of the real structure on the linear thermal expansion coefficient of A15‐type intermetallic compounds from room temperature to 10K
Authors: Herold A. , Försterling G. , Kleinstück K.
Published: July 2007

The temperature dependence of the thermal expansion coefficient of a number of A15‐compounds was investigated by X‐ray diffraction experiments. The expansion coefficient of the high‐temperature superconductors with the A15‐structure is highly temperature dependent and has negative values below 100K. Deviations from the stoichiometric composition, substitution of foreign atoms and lattice distortions prevent negative values of the expansion coefficient. The results are discussed in connection with other physical properties of these compounds.
On growth and morphological studies of TGS single crystals
Authors: Pandya G. R. , Vyas D. D.
Published: July 2007

The effect of various growth parameters; seed morphology, growth‐temperature and pH of the mother solution on the growth of TGS single crystals is studied. The effect of these variables on the crystal morphology and perfection is reported. It is shown that; (i) The crystal quality is much dependent on the seed and the growth temperature and (ii) the pH‐control is a simple and an effective method for obtaining TGS crystals of required morphology.
The teachers/practitioners corner forecasting in business schools: A survey
Authors: Hanke John
Published: July 2007

The study of forecasting techniques has received increased attention in recent years. How to incorporate this topic into the business school curriculum is a frequent subject of discussion. The purpose of this study was to determine whether forecasting is being taught in business schools and how it is incorporated into the curriculum. The survey instrument was sent to 622 member institutions of the American Assembly of Collegiate schools of Business. The importance of teaching forecasting techniques at both the undergraduate and graduate level was investigated.
Short‐term forecasting of industrial production by means of quick indicators
Authors: Teräsvirta Timo
Published: July 2007

This paper reports results on building transfer function models with linear combinations of quick indicators as inputs for very short‐term prediction of the monthly time series of the volume of industrial production in Finland. The number of input variables in the transfer function models is reduced in two alternative ways: by replacing the original indicators by their two first principal components and by omitting certain indicators. The prediction accuracy of the transfer function models is checked outside the sample and found superior to that of corresponding ARIMA models. Neither of the two ways of reducing the number of input variables leads to consistently more accurate forecasts than the other. It is also found that the prediction accuracy of the transfer function models compares rather favourably with the preliminary values of the volume of industrial production published by the Central Statistical Office during the periods of rapid growth.
The role of time series analysis in the evaluation of econometric models
Authors: Longbottom J. A. , Holly S.
Published: July 2007

This paper compares the properties of a structural model—the London Business School model of the U.K. economy—with a time series model. Information provided by this type of comparison is a useful diagnostic tool for detecting types of model misspecification. This is a more meaningful way of proceeding rather than attempting to establish the superiority of one type of model over another. In lieu of a better structural model, the effects of inappropriate dynamic specification can be reduced by combining the forecasts of both the structural and time series models. For many variables considered here these provide more accurate forecasts than each of the model types alone.
Forecasting demand in international markets: The case of correlated time series
Authors: Ofir Chezy , Raveh Adi
Published: July 2007

In this paper a data analysis tool for analyzing highly correlated time series data is suggested. The main objective is to unify multiple time series into a single series and then apply a univariate method for the purpose of prediction. This method is essentially efficient for analyzing multiple time series with sparse data. Several time series data of relative demand for black and white television receivers in various countries are analyzed and quite accurate predictions are obtained.
Forecasting commercial electricity sales
Authors: Watson Mark W. , Pastuszek Lydia M. , Cody Eric
Published: July 2007

An important component of the New England Electric System Companies' (the 'System') total electricity sales is attributable to commercial customers. Commercial growth has recently been strong; moreover the System's peak demand is highly sensitive to commercial load. In a typical month this class represents 33 per cent of total System sales. Accurate short‐run forecasts of total kWh sales are important for rate making, budgeting, fuel cause proceedings, and corporate planning. In this study we use a variety of econometric and time‐series techniques to produce short‐run forecasts of commercial sales for two geographical areas served by two separate retail companies;.
Forecasting vehicle holdings and usage with a disaggregate choice model
Authors: Berkowitz Michael K. , Gallini Nancy T. , Miller Eric J. , Wolfe Robert A.
Published: July 2007

A case study in which a three‐stage choice model of Canadian household vehicle holdings and usage is used to generate short‐run forecasts of changes in household vehicle usage and gasoline consumption in response to a range of energy‐related policies. The objectives of this case study are to (1) demonstrate the application of disaggregate choice modelling methods to the generation of policy‐relevant forecasts of travel behaviour; (2) draw implications from this forecasting exercise concerning the likely impacts of various energy‐related policies; and (3) assess some of the strengths and weaknesses of the current state‐of‐the‐art of forecasting with disaggregate choice models, using the presented study as a case in point.
Comments on testing for forecast and specification optimality using linear composites
Authors: Phillips Robert F.
Published: July 2007

This paper extends the method of using linear composites of forecasts for testing the efficiency of one forecast compared to a finite collection of other forecasts. It also gives necessary and sufficient conditions for forecast optimality in the mean square error sense. Information sets are found to be unnecessary for forecast optimality. Finally, the paper shows that a consistent test of forecast optimality cannot in general be obtained using linear composites. A similar conclusion applies to tests of specification optimality based on linear composites.
Combining algorithms based on robust estimation techniques and co‐integrating restrictions
Authors: Hallman J. , Kamstra M.
Published: July 2007

This paper will motivate alternative combining schemes, provide a statistic for comparing alternative combinations out‐of‐sample and provide an example demonstrating these techniques. The evidence suggests the proposed procedures are likely to do no worse than other approaches and promise to do better under circumstances commonly encountered with economic data: integrated series and contaminated data.
The combining of forecasts using recursive techniques with non‐stationary weights
Authors: Sessions D. N. , Chatterjee S.
Published: July 2007

This paper evaluates six optimal and four ad hoc recursive combination methods on five actual data sets. The performance of all methods is compared to the mean and recursive least squares. A modification to one method is proposed and evaluated. The recursive methods were found to be very effective from start‐up on two of the data sets. Where the optimal methods worked well so did the ad hoc ones, suggesting that often combination methods allowing ‘local bias’ adjustment may be preferable to the mean forecast and comparable to the optimal methods.
Seasonal adjustment and kalman filtering: Extension to periodic variances
Authors: Eiurridge Peter , Wallis Kenneth F.
Published: July 2007

This paper reviews the relations between the methods of seasonal adjustment used by official statistical agencies and the ‘model‐based’ methods that postulate explicit stochastic models for the unobserved components of a time series and apply optimal signal extraction theory to obtain a seasonally adjusted series. The Kalman filter implementation of the model‐based methods is described and some recent results on its properties are reviewed. The model‐based methods employ homogeneous or time‐invariant models that assume in particular that the autocovariance structure does not vary with the season. Relaxing this leads to the class of models known as periodic models, and an example of a seasonally heterosceclastic unobserved‐components ARIMA (SHUCARIMA) model is presented. The calculation of the standard error of a seasonally adjusted series via the Kalman filter is extended to this periodic model and illustrated for a monthly rainfall series.
Predicting small region sectoral responses to changes in aggregate economic activity: A time series approach
Authors: Weller Barry R.
Published: July 2007

The purpose of this paper is to investigate the applicability of a contemporary time series forecasting technique, transfer function modeling, to the problem of forecasting sectoral employment levels in small regional economies. The specific sectoral employment levels to be forecast are manufacturing, durable manufacturing, non‐durable manufacturing and non‐manufacturing employment. Due to data constraints at the small region level, construction of traditional causal econometric models is often very difficult; thus time series approaches become particularly attractive. The results suggest that transfer function models using readily available national indicator series as drivers can provide more accurate forecasts of small region sectoral employment levels than univariate time series models.
Forecasting environmental change
Authors: Beck M. B.
Published: July 2007

A context and introduction are provided for nine contributed articles on Forecasting Environmental Change. Since the first quantitative studies of the ‘predicament of mankind’ at the end of the 1960s, large‐scale forecasting models have attracted substantial criticism on the grounds of failing both to inform the policy process and to embrace the notion of surprise‐rich futures. Almost all attempts at developing models of environmental systems, at whatever scale, have been dogged by the sceptic's question: Is the model capable of predicting conditions substantially different from those observed in the past? The question, strictly speaking, is not answerable. The paper defines therefore three approaches to the development of modelsthe mechanical, metric, and linguistic paradigmsand constructs thence a reorientation of the customary problem of prediction in order to explore the concept of reachable, and radically different, futures. Such reorientation depends crucially on a juxtaposition of the linguistic and mechanical descriptions of a system's behaviour. The nine papers of this special issue are then summarized in the context provided by this reconsideration of how we formalize our thinking about the behaviour of systems, and of what might be meant by the systematic analysis of reachable futures.
The impact of forecasting methodology on the accuracy of national population forecasts: Evidence from the Netherlands and Czechoslovakia
Authors: Keilman Nico , Kučera Tomaš
Published: July 2007

This study considers the accuracy of national population forecasts of the Netherlands and the Czechoslovak Socialist Republic (CSSR) produced by the statistical agencies of these countries after World War II. Attempts are made to link patterns of ex‐post errors to changes in forecasting methodology. We look at the demographic components employed in each forecast, the procedure to extrapolate fertility and the level at which assumptions for each component are formulated. Errors in total population size, fertility, mortality and foreign migration, and age structure are considered. We discuss trends in errors and methodology since 1950 and compare the situations in the two countries. The findings suggest that methodology has only a very limited impact on the accuracy of national population forecasts.
Co‐integration, error correction and improved medium‐term regional VAR forecasting
Authors: Shoesmith Gary L
Published: July 2007

This study investigates possible improvements in medium‐term VAR forecasting of state retail sales and personal income when the two series are co‐integrated and represent an error‐correction system. For each of North Carolina and New York, three regional vector autoregression (VAR) models are specified; an unrestricted two‐equation model consisting of the two state variables, a five‐equation unrestricted model with three national variables added and a Bayesian (BVAR) version of the second model. For each state, the co‐integration and error‐correction relationship of the two state variables is verified and an error‐correction version of each model specified. Twelve successive ex ante five‐year forecasts are then generated for each of the state models. The results show that including an error‐correction mechanism when statistically significant improves medium‐term forecasting accuracy in every case.
Estimating the strength of expert judgement: The case of US mortality forecasts
Authors: Alho Juha M.
Published: July 2007

The use of expert judgement is an important part of demographic forecasting. However, because judgement enters into the forecasting process in an informal way, it has been very difficult to assess its role relative to the analysis of past data. The use of targets in demographic forecasts permits us to embed the subjective forecasting process into a simple time‐series regression model, in which expert judgement is incorporated via mixed estimation. The strength of expert judgement is denned, and estimated using the official forecasts of cause‐specific mortality in the United States. We show that the weight given to judgement varies in an improbable manner by age. Overall, the weight given to judgement appears too high. An alternative approach to combining expert judgement and past data is suggested.
A comparison of models for forecasting the discovery of hydrocarbon deposits
Authors: Power M. , Fuller J. D.
Published: July 2007

There are many geologic resource assessment techniques available that can be used to estimate the hydrocarbon potential of frontier basins. The techniques do not, however, produce discovery rate forecasts, which are critical to government and industry planners. Various methods of predicting the discovery rate in frontier basins are reviewed and appraised within the context of the drilling history of Canada's Scotian Shelf. The reviewed models include a mean historical discovery rate technique, the exponential decline model, a logistic curve technique and a class of models based on a sampling without replacement approach to prediction. Models are found to perform best over the longer forecast horizons, with those models based on the sampling without replacement technique tending to perform best.
Modelling peak electricity demand
Authors: Engle Robert F. , Mustafa Chowdhury , Rice John
Published: July 2007

This paper estimates a forecasting equation for the hourly peak electricity demand one day in the future. The models incorporate deterministic influences such as holidays, stochastic influences such as average loads by building bivariate models, and exogenous influences such as the weather which is given a careful non‐linear formulation. Out‐of‐sample comparisons are made using an additional year of data.
The uses and abuses of ‘consensus’ forecasts
Authors: McNees Stephen K.
Published: July 2007

Clemen's (1989) review of the forecast‐combining literature amply illustrates both the interest in and the importance of this subject. This article stresses the tautological properties of various consensus measures that assure their success relative to most individual forecasts. It confirms the finding of earlier studies that for each specific macroeconomic variable roughly one‐third of individual forecasters are more accurate than a consensus. However, each individual does relatively poorly for some variable while the consensus, in contrast, necessarily never fails relative to most individuals. These results, like most previous studies, describe consensus measures that are synthetic constructs derived from a pre‐existing set of individual forecasts. Strictly speaking, this contemporaneous consensus is not available to individual forecasters when their forecasts are made. A prior consensus measure, which is in their information sets, was relatively much less accurate than the contemporaneous measure. Nevertheless, a small subset of individual forecasters were generally inferior to the known, prior consensus forecast.
Forecast combination in a dynamic setting
Authors: Edward Coulson N. , Robins Russell P.
Published: July 2007

We examine the implications of allowing lags into forecast combination regressions, thereby extending previous models. The practical conclusion is that lagged dependent variables, but not lagged forecasts, improve forecast combination procedures. Also, improvements are obtained when nonstationarity of the data is recognized.
Testing weak rationality of forecasts with different time horizons
Authors: Kirchgässner G.
Published: July 2007

Starting with conventional tests for weak rationality, we show how additional tests can be performed if predictions with different time horizons are commonly used in them. Next, we show that most of these tests can still be applied if the structure of the economic system changes but only some of them if the true system is unknown. Finally, these tests are applied to the semi‐annual one‐and two‐step predictions of the group of five leading economic research institutes in the Federal Republic of Germany. For the two‐step predictions we find more evidence against the rational expectations hypothesis than for the one‐step predictions.
Combining exchange rate forecasts: What is the optimal consensus measure?
Authors: Macdonald Ronald , Marsh Ian W.
Published: July 2007

In this paper a high‐quality disaggregate database is utilized to examine whether individual forecasters produce efficient exchange rate predictions and also if the properties of the forecasts change when they are combined. The paper links a number of themes in the exchange rate literature and examines various methods of forecast combination. It is demonstrated, inter alia, that some forecasters are better than others, but that most are not as good as a naive no‐change prediction. Combining forecasts adds to the accuracy of the predictions, but the gains mainly reflect the removal of systematic and unstable bias.
Seven components of judgmental forecasting skill: Implications for research and the improvement of forecasts
Authors: Stewart Thomas R. , Lusk Cynthia M.
Published: July 2007

A decomposition of the Brier skill score shows that the performance of judgmental forecasts depends on seven components: environmental predictability, fidelity of the information system, match between environment and forecaster, reliability of information acquisition, reliability of information processing, conditional bias, and unconditional bias. These components provide a framework for research on the forecasting process. Selected literature addressing each component is reviewed, and implications for improving judgmental forecasting are discussed.
Combining experts' opinions using a normal‐wishart model
Authors: Wiper Michael P. , French Simon
Published: July 2007

This paper examines how a Bayesian decision maker might update her distributions for continuous variablesXi, i=1, 2, …, upon hearing experts' forecasts expressed as quantiles. To utilize the relationship between the decision maker and experts, and to avoid problems associated with different scales and ranges of the variables, we assume that the decision maker transforms the experts' quantiles in terms of her own prior distribution for eachXi.A model using such a transformation is presented and its properties are examined.
Quarterly forecasts of the italian business cycle by means of monthly economic indicators
Authors: Parigi G. , Schlitzer G.
Published: July 2007

Recent years have witnessed a growing availability of high‐frequency indicators which can be used to forecast future economic activity. This paper shows how some of the widely known monthly economic indicators at present available in Italy can be used in a systematic and coordinated manner to forecast the main variables of the National Accounts. In order to reduce as much as possible the amount of judgment in the analysis of the business cycle, a model‐based approach is adopted. Thus, a pseudo macro‐econometric model of the Italian economy is built, which can be used to produce forecasts one semester ahead of the last National Accounts data release. The model can be used autonomously as well as in combination with the Bank of Italy's quarterly econometric model.
Structural, VAR and BVAR models of exchange rate determination: A comparison of their forecasting performance
Authors: Sarantis Nicholas , Stewart Chris
Published: July 2007

This paper compares the out‐of‐sample forecasting accuracy of a wide class of structural, BVAR and VAR models for major sterling exchange rates over different forecast horizons. As representative structural models we employ a portfolio balance model and a modified uncovered interest parity model, with the latter producing the more accurate forecasts. Proper attention to the long‐run properties and the short‐run dynamics of structural models can improve on the forecasting performance of the random walk model. The structural model shows substantial improvement in medium‐term forecasting accuracy, whereas the BVAR model is the more accurate in the short term. BVAR and VAR models in levels strongly out predict these models formulated in difference form at all forecast horizons.
Design of an optical system to extract the image of the pupil for gaze detection
Authors: Tomono Akira
Published: July 2007

A system to detect eye direction via image processing is being studied for a better human‐machine interface. It is important in this method that feature points relating to an eye be extracted stably.

This paper proposes the design of an optical system which efficiently extracts the image of a pupil as a feature point from its background. The image of a pupil can clearly be recorded by a camera by illuminating the eye with an infrared ray which is reflected from the fundus of the eye and exits through the pupil. However, the distribution of the brightness of the pupil image varies widely depending on the relative position of the ray sources.

To analyze these conditions, an eye model consisting of a transparent double‐sphere is introduced. Using this model and a ray‐tracing method, the conditions of the illumination to provide an even image of the entire pupil have been obtained. The result shows that the ray sources should be arranged symmetrically within a specific radius of the optical axis of the camera lens. The calculation based on these conditions agrees with the experimental results, showing the effectiveness of this simulation.

The conditions to make the image of a pupil dark have also been obtained by applying the same method. To emphasize the contrast of the image of a pupil against its background, a method using a single camera and two ray sources having different conditions is proposed; the camera produces a set of two images of a pupil (bright and dark), and then the difference of the images is simply digitized.
A summation algorithm with error correction for parallel computers
Authors: Ozawa Kazufumi , Miyazaki Masatoshi
Published: July 2007

This paper proposes an algorithm to accurately compute the sum of floating‐point numbers on parallel computers. This algorithm is an extension of the well‐known recursive doubling technique which computes the sum of n floating‐point number in log2n parallel steps. The time complexity of the present algorithm also is O(log n), and the space complexity is O(n). This algorithm enables a highly accurate result to be obtained with guarantee. The theoretical analysis and the numerical experiments on a parallel computer show that this algorithm is as accurate as Kahan's, which is the fastest and an accurate serial algorithm for the summation of the numbers, and also that the present algorithm is faster than Kahan's provided that two or more processors are available.
Construction of pseudorandom permutations
Authors: Ohnishi Yasuhiro , Maruoka Akira
Published: July 2007

The permutation from {0, 1}2n to {0, 1}2n represented by S(f) in DES (Data Encryption Standard) is used as the basic operation. Let f be a function from {0, 1}n to {0, 1}n and ⊕ denote bitwise exclusive or. Then S(f) is defined S(f)(L.R) = R.[L⊕f(R)] where L, R ϵ {0, 1}n, Moreover, let S(f2, f1, fo) denote the composition of S(f2, S(f1) and S(fo), and {S(f2, f1,fo)} denote a set of S(f2,f1,fo) obtained when fo,f1 and f2 are chosen randomly from a set of pseudorandom functions. Luby et al. have shown that {S(f2,f1,fo)} is pseudorandom.

This paper investigates the case in which there are two different pseudorandom functions and shows that while {{S(f1, f1,, fo)} and {S(f1, fo, fo)} are pseudorandom, {S(fo, f1, fo)} is not.