bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and study of extremely pure naf single crystals
Authors: Voszka R. , Raksányi K. , Földvári I. 
Published: July 2007

AbstractThe authors employed various physical and chemical methods for the purification of NaF. The efficiency of these methods was controlled by absorption measurements and chemical analysis. From purified material a single crystal was grown in every case, the absorption of which was measured by a vacuum ultraviolet spectrophotometer in the far UV wavelength range. The absorption at 142 nm was found to be indicative of the presence of several transition and heavy metal ions. The effect of doping with several alkaline and alkaline earth ions and furthermore with Cl− and OH− ions on these spectra is discussed. It is shown that certain chemical methods used for purification introduce Cl− ions into the material which are detectable by UV‐spectrophotometry.
Strahlende Rekombination aus Nichtgleichgewichtszuständen in katodenstrahlangeregtem GaN
Authors: Schwabe R. , Zehe A. , Hänsel T. 
Published: July 2007

AbstractEs wird die strahlende Rekombination elektronenstrahlangeregter heißer Träger bei der Temperatur des flüssigen Neons untersucht. Dabei wird ein Lumineszenzpeak oberhalb der freien Exzitonenenergie bei 3,495 eV gefunden, das wahrscheinlich auf einen Band‐Band‐Übergang freier Träger zurückzuführen ist. Die hohe Trägerkonzentration erzeugt ein thermisches Quasigleichgewicht im Elektronensystem, das durch eine verallgemeinerte Temperatur Te beschrieben werden kann. Diese Temperatur ist höher als die Gittertemperatur und wächst mit steigender Anregungsdichte. Aus der Abhängigkeit der Temperatur Te von der erzeugten Überschußladungsträgerdichte ergibt sich als dominanter Energieverlustmechanismus die polar‐optische Streuung.
Punktdefekte und Überstrukturerscheinungen in CdSe‐Epitaxieschichten
Authors: Däweritz L. 
Published: July 2007

AbstractAn im Hochvakuum aufgedampften CdSe‐Schichten auf CaF2‐Spaltflächen werden Transmissionselektronenbeugungsdiagramme mit Überstrukturreflexen beobachtet. Diese Überstrukturerscheinungen werden durch eine geordnete Verteilung von Punktdefekten erklärt und mit Berechnungen nach der Debye‐Hückel‐Theorie verglichen. Es wird gezeigt, daß infolge von Abweichungen von der stöchiometrischen Zusammensetzung das Auftreten der Zinkblende‐ und Wurtzitstruktur in vielen Fällen nicht allein auf der Basis der dielektrischen Strukturtheorie nach PHILLIPS und VAN VECHTEN erklärt werden kann.
Zum Einfluß der Diffusion auf Keimbildung und Wachstum bei der Kristallzüchtung aus der Gasphase
Authors: Kersten F. , Hamann C. 
Published: July 2007

AbstractCharakteristika des Wachstums bei der Kristallzüchtung durch Sublimation/Desublimation im Inertgas haben ihre Ursache in der Diffusion des Nährstoffes zur Wachstumsfront, Für zwei idealisierte Grenzfälle werden die Diffusionsfelder berechnet und für die bei praktischen Züchtungen vorliegenden Bedingungen diskutiert.
Wachstum von Graphitkristallen in kohlenstoffhaltigen Eisenschmelzen bei höheren Überschreitungen
Authors: Herfurth K. , Ziegler E. 
Published: July 2007

AbstractWachstumsgeschwindigkeiten für die Basis‐ und die Prismenflächen von Graphitkristallen werden in Abhängigkeit von der Überschreitung unter der Voraussetzung berechnet, daß die Flächen bei hohen Überschreitungen über zweidimensionale Keimbildung aus einer Eisen—Kohlenstoff‐Schmelze wachsen. Es zeigt sich, daß in der Nähe des Gleichgewichts Prismenflächen schneller als Basisflächen wachsen. Bei hohen Überschreitungen kehrt sich dagegen das Verhältnis der Wachstumsgeschwindigkeiten um. Diese Ergebnisse sind geeignet, die unterschiedlichen Graphitformen in Gußeisen zu erklären.
Effect of preliminary processing on the parameters of deformation curves and structure of slip lines of MgO crystals
Authors: Alybaeva N. R. , Berezhkova G. V. , Govorkov V. G. 
Published: July 2007

AbstractThe effect of annealing, chemical and mechanical polishing on the form of stress‐strain curves, the values of yield strength and work hardening rates and on the density and structure of slip lines was investigated.
Supersaturation and crystal size distribution changes during the precipitation of Nickel ammonium sulphate hexahydrate
Authors: Mullin J. W. , Ang H.‐M. , Ang H.‐M. 
Published: July 2007

AbstractThe desupersaturation of nickel ammonium sulphate aqueous solutions, during the precipitation of the hydrated salt, has been followed by refractive index measurements. The addition of seed crystals has a considerable effect on the desupersaturation process: the induction and latent periods and the crystal size distribution are all greatly reduced.The precipitated crystal size follows V. WEIMARN'S rules, viz, the median size (a) passes through a maximum with increasing supersaturation for a given crystallization time, and (b) decreases with increasing supersaturation, for precipitations which have virtually ceased. The crystal yield increases with both supersaturation and time, but the size distribution remains fairly constant with time for supersaturations, S > 2.
LEED‐AES‐Untersuchungen der Oxydation von austenitischen Cr‐Ni‐Stählen an der (100)‐Ebene
Authors: Adolphi B. , Müssig H.‐J. 
Published: July 2007

AbstractEs wird die Oxydation von austenitischem Cr–Ni‐Stahl an der (100)‐Fläche untersucht. Der betrachtete Temperaturbereich reicht von Raumtemperatur bis zu 1000°C. Die Oxydation beginnt mit der Bildung von Chromoxid (Cr2O3). Anschließend entsteht Eisenoxid (Fe3O4), das im Laufe der Reaktion das Chromoxid zudeckt. Bei 500°C zerfällt Fe3O4 und wächst die Chromoxidschicht. Bei 700°C beobachtet man im LEED‐Bild Cr2O3(111) und ab 750°C kann man darauf FeO(111) nachweisen. Ab 1000°C ist die Oxidschicht zerstört. Alle angeführten Oxide wachsen inselförmig.
Matrixprobleme in der Augerelektronenspektroskopie von Cu‐Ag‐Legierungen verschiedener Zusammensetzung
Authors: Streubel P. , Berndt H. , Meisel A. 
Published: July 2007

AbstractAnhand der beiden Grenzfälle einer Cu–Ag‐Legierung mit sehr großem Ag‐ bzw. Cu‐Gehalt konnte die Konzentrationsabhängigkeit der matrixspezifischen Parameter Rückstreufaktor r und mittlere Austrittstiefe λ nachgewiesen werden. Die Quotienten rCu/rAg bzw. λCu/λAg unterscheiden sich für diese beiden Grenzfälle um etwa 4% bzw. 2%. Der Rückstreufaktor r wurde durch numerische Integration aus Rückstreuverteilungskurve Nr(E) und Ionisierungsquerschnitt σ erhalten. – Der berechnete Empfindlichkeitsfaktor SCu zeigt ebenfalls eine Konzentrationsabhängigkeit. Die Werte für SCu weichen von einem Grenzfall zum anderen um etwa 6% ab. – Der Vergleich der berechneten Empfindlichkeitsfaktoren SCu mit experimentell bestimmten Augerergiebigkeitsfaktroen 1/KCu von Braun und Färber verdeutlicht neben der Konzentrationsabhängigkeit den starken Einfluß der Probenvorbehandlungsmethoden auf 1/KCu. Die Feststellung von Färber für diesen Fall, daß das Sputtern als Vorbehandlung von einem Zweiphasensystem wie der Cu–Ag‐Legierung am besten geeignet ist, konnte bestätigt werden.
Einfluß der mechanischen Aktivierung auf Struktur und Reaktivität apatitischer Phosphate
Authors: Pöthig R. , Dünkel L. , Paudert R. , Harenz H. , Grimmer A.‐R. 
Published: July 2007

AbstractDie mechanische Aktivierung von Apatiten führt zur Erhöhung der Lösbarkeit in Citronensäure und alkalischer Ammoncitratlösung. Die Textur‐ und Strukturveränderungen des Festkörpers werden als Ursachen für die Lösbarkeitserhöhung dargestellt.
Zur Struktur mechanisch erzeugter amorpher Quarzschichten
Authors: Steinike U. , Müller B. , Ebert I. , Hennig H.‐P. 
Published: July 2007

AbstractDurch die mechanische Bearbeitung in einer Schwingmühle wird eine Amorphisierung des Quarzes erreicht, indem die Fernordnung aufgehoben wird. Die durch den Quarz vorgeprägte Nahordnung bleibt jedoch für r < 0.65 nm zu rund 50% bestehen. Die Struktur des durch mechanische Bearbeitung zerstörten Quarzes unterscheidet sich im Nahordnungsbereich von der der amorphen Kieselsäure. Die Entstehung von Sauerstoffdefektelektronen‐Zentren, die an die O2‐Anwesenheit gebunden sind, wird im Zusammenhang mit der mechanisch zerstörten Quarzstruktur diskutiert.
Changes in Structure of ZnS Crystals Due to Mechanical Stresses
Authors: Farkas‐Jahnke M. , Gács P. 
Published: July 2007

AbstractUsing the direct X‐ray diffraction method which was worked out for the case of lattices built up of translationally equivalent layers for the determination of the rat of occurrences of structure elements in crystal regions consisting of 3, 4 and 5 layers, respectively, structure changes in ZnS crystals due to mechanical stresses were investigated.Forces acting parallel to the [110] direction induced a decrease in the number of stackings containing hexagonal elements and increase in the number of cubic stackings. A lattice region of a ZnS crystal having originally pure 4 H structure became heavily stacking faulted when polished parallel to the (110) plane; repeated polishing results in a twinned cubic structure.
Growth of defect‐free Sr1−xBaxNb2O6 (SBN) crystals
Authors: Reiche P. , Schalge R. , Bohm J. , Schultze D. 
Published: July 2007

AbstractSBN single crystals are grown by the Czochralski technique. Growth defects (striations, dislocations, twin lamellae) are investigated as depending on growth conditions. Crystals almost free from growth defects and applicable to optical devices are prepared by an optimized growth technology.
The Czochralski growth of doped bismuth‐germanium oxide (BGO) and bismuth‐silicon oxide (BSO) single crystals
Authors: Łukasiewicz T. , Żmija J. 
Published: July 2007

AbstractDoped single crystals of BGO and BSO with Cr, Mn, Cu, Ni have been grown. The conditions for the growth of doped single crystals by the Czochralski method have been determined, analyses of distributions of dopants in the crystals have been made. For the Mn, Cr, Cu, doped crystals changes of coloration after illumination with visible light have been observed.
Non‐crystallographic symmetries in the superstructure of (NH4)2ZnCl4
Authors: Warczewski J. 
Published: July 2007

AbstractThe modulation vector turned out to be equal 1/4. The lattice constants of the orthorhombic superstructure are determined: a = 12.6197(16) Å, b = 7.2107(81) Å, c = 4 × 9.2746(15) Å. The two of the four absences rules are interpreted as corresponding to the non‐crystallographic symmetries:
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The space group P 21cn is determined on the basis of the single crystal X‐ray pictures taking into account the experimental evidence of pyroelectricity in (NH4)2ZnCl4.
Isotopic method for studying the kinetics of crystal growth
Authors: Misztal S. , Kołek A. , Koch R. 
Published: July 2007

AbstractAn experimental method for studying the kinetics of crystal growth based on the knowledge of crystal size distribution in the crystallizer is presented. Residence time distribution was determined using the radioactive isotopes technique. The method was employed to determine the magnesium sulphate growth kinetics in high temperature conditions.
Qualitative and quantitative determination of X‐ray trajectories
Authors: Dietrich B. , Härtwig J. 
Published: July 2007

AbstractX‐Ray trajectories are qualitatively determined only from the behaviour of the potential (of the lattice distance) in crystals with x‐dependent deformation gradients. the quantitative calculations show the varying degrees of sensitivity of X‐ray trajectories to deformation for different radiations, different orders of reflection and different maximum values of relative change of lattice distance.
Crystal growth from concentrated aqueous solutions of calcium nitrate
Authors: Paćk P. , Oesterreicherová H. 
Published: July 2007

AbstractThe crystal growth kinetics was studied in the system of calcium nitrate – water at concentrations 14.3, 11.1, and 9.1 mole% of Ca(NO3)2 within the supercooling region ΔT = 0–65 K. The mechanism of the growth was suggested and the concentration dependence of the crystal growth rate was discussed.
Anomalous behaviour of LaMnO3 with small structure distortions in magnetic phase transitions range
Authors: Sirota N. N. , Pavlov V. I. , Bogush A. K. , Karvay A. P. 
Published: July 2007

AbstractThe magnetic field effect on conductivity and intensity of the magnetic neutron diffraction reflections as well as magnetization of lanthanum manganite with different crystal lattice distortions in the ferromagnetic‐paramagnetic transitions range are investigated. It is shown that in the investigated samples near the paramagnetic‐ferromagnetic transition temperature at H = 0 there exists a relatively wide transition range where the magnetic ordering occurs with a relatively small external magnetic field applied.
Bulk crystals of PbTe synthesized by the iodide method
Authors: Karagiozov L. , Trifonova E. P. , Yakimova R. T. 
Published: July 2007

AbstractBulk crystals have been prepared for the first time from PbTe synthesized by low‐temperature iodide method. Their basic structural, physico‐chemical and electrical parameters as a result of certain technology conditions have been investigated.
Identification of the multi‐input box‐Jenkins transfer function model
Authors: Edlund Per‐Olov 
Published: July 2007

AbstractIn this paper different ways to identify the order of the Box–Jenkins transfer function model are discussed. The discussion concerns estimation of the impulse response weight function in the case of more than one input variable. It is found that most of the existing methods are either unsuitable when there is more than one input variable, or expensive or difficult to use. To overcome these deficiencies an extended regression method is proposed. The new method is based on the solution of some problems in connection with the use of the regression method. The impulse response weights are estimated by a biased regression estimator on variables transformed with respect to the noise model. To test the new approach a small simulation experiment has been performed. The results from the simulations indicate that the proposed method may be of value to the practitioner.
Forecasting and the database: An analysis of databases for international business
Authors: Rice Gillian , Mahmoud Essam 
Published: July 2007

AbstractA major consideration in the selection of a forecasting method for a specific situation is the type of pattern in the data. Before the data pattern is identified, the forecaster must recognize the dependence of any forecasting method upon the accompanying reliable database. This issue is discussed in the paper with reference to databases for international business.
Application of the linear partial information model to forecasting the Swiss timber market
Authors: Zimmermann A. , Zweifel P. , Kofler E. 
Published: July 2007

AbstractMost often, statistical analyses only provide partial information about the appropriateness of different models, structures and parameters which may underlie the dynamic process that has generated a time series. Linear partial information (LPI), in particular, consists of linear restrictions such as LPI: pa> pb, pa> pc where pa denotes the probability that structure a holds. Fuzzy information of this type can be put to use for decision‐making by LPI analysis. In this paper, LPI analysis is applied to answer the question of whether subsidizing price, given an abnormal disturbance on the timber market, would contribute to continuous forest management, a stated goal of Swiss environmental policy.
Sales forecasting using multi‐equation transfer function models
Authors: Liu Lon‐Mu 
Published: July 2007

AbstractThe purpose of this study is first, to demonstrate how multivariate forecasting models can be effectively used to generate high performance forecasts for typical business applications. Second, this study compares the forecasts generated by a simultaneous transfer function model (STF) model and a white noise regression model with that of a univariate ARIMA model. The accuracy of these forecasting models is judged using their residual variances and forecasting errors in a post‐sample period. It is found that ignoring the residual serial correlation can greatly degrade the forecasting performance of a multi‐variable model, and in some situations, cause a multi‐variable model to perform inferior to a univariate ARIMA model. This paper also demonstrates how a forecaster can use an STF model to compute both the multi‐step ahead forecasts and their variances easily.
Forecast comparisons of four models of U.S. interest rates
Authors: Craine Roger , Havenner Arthur M. 
Published: July 2007

AbstractIn this paper we compare the out of sample forecasts from four alternative interest rate models based on expanding information sets. The random walk model is the most restrictive. The univariate time series model allows for a richer dynamic pattern and more conditioning information on own rates. The multivariate time series model permits a flexible dynamic pattern with own‐ and cross‐series information. Finally, the forecasts from the MPS econometric model depend on the full model structure and information set.In theory, more information is preferred to less. In practice, complicated misspecified models can perform much worse than simple (also probably misspecified) models. For forecasts evaluated over the volatile 1970s the multivariate time series model forecasts are considerably better than those from simpler models which use less conditioning information, as well as forecasts from the MPS model which uses substantially more conditioning information but also imposes ‘structural’ economic restrictions.
Predicting nuclear incidents
Authors: Chow Tat Chi , Oliver Robert M. 
Published: July 2007

AbstractIn this paper we review earlier work in predicting incidents of like severity in nuclear power plants. Attention is focused on nuclear core‐melts which can lead to disastrous releases of radioactivity. By combining engineering knowledge with operational experience, we attempt to predict observable quantities such as the time to the next incident and the number of incidents in a fixed future period. The prior distribution of failure rates is obtained from Rasmussen et al (1975), the well‐known Wash‐1400 study. It is then compared with the Gamma prior, and conditions under which the latter is appropriate to use are discussed. The paper concludes with estimates of the expected time to the first core‐melt, the median and quantiles of time to the next partial core‐melt and the probability that at least one severe incident will occur in the next decade. Operating experience to data indicates that while the failure rate of complete core‐melt has been decreasing, that of partial core‐melt has increased dramatically.
Minimum variance pooling of forecasts at different levels of aggregation
Authors: Fuhrer Jeff , Haltmaier Jane 
Published: July 2007

AbstractThe most common approach to combining forecasts at different levels of aggregation has been to sum (or average) the more disaggregated forecast, and take a weighted average of the aggregate forecasts. This paper develops a simple method for obtaining minimum variance pooled forecasts at the disaggregated level. The major advantage that this method has over the common approach is that it provides pooled forecasts at both the aggregated and disaggregated level. As will be shown, the resulting aggregate pooled forecast is identical to the forecast which would be obtained by simply pooling two forecasts at the aggregate level, while the disaggregated forecast maintains the aggregation identity required by the problem.
Reducing uncertainty in short‐term projections: Linkage of monthly and quarterly models
Authors: Corrado Carol , Greene Mark 
Published: July 2007

AbstractThis paper shows how monthly data and forecasts can be used in a systematic way to improve the predictive accuracy of a quarterly macroeconometric model. The problem is formulated as a model pooling procedure (equivalent to non‐recursive Kalman filtering) where a baseline quarterly model forecast is modified through ‘add‐factors’ or ‘constant adjustments’. The procedure ‘automatically’ constructs these adjustments in a covariance‐minimizing fashion to reflect the revised expectation of the quarterly model's forecast errors, conditional on the monthly information set. Results obtained using Federal Reserve Board models indicate the potential for significant reduction in forecast error variance through application of these procedures.
Effects of difficulty on judgemental probability forecasting of control response efficacy
Authors: Harvey N. 
Published: July 2007

AbstractA judgemental control task was framed as a problem of medical decision making. The control parameter of a recursive system (i.e. a patient) was initially set so that output (i.e. a diagnostic index) fell outside a designated criterion range (corresponding to health). Subjects were told to bring the system's output into the designated range by resetting this control parameter (by specifying the dose of a drug). After each of these control responses, they made a probabilistic forecast that it would have the desired effect. It was found that these forecasts were more overconfident when the control task was more difficult but that the reason for this varied. When difficulty was manipulated across subjects, there was little evidence that lower control performance was associated with any lowering of the probabilistic forecasts. When difficulty was manipulated within subjects, they did lower their forecasts for more difficult task variants but did so insufficiently. In fact, relations between probabilistic forecasts of control response efficacy and proportion of those responses that were actually effective was linear with a slope of 0.44.
Multiple prediction intervals for time series: Comparison of simultaneous and marginal intervals
Authors: Ravishanker N. , Wu L. Shiao‐yen , Glaz J. 
Published: July 2007

AbstractSimultaneous prediction intervals for forecasts from time series models that contain L (L ≤ 1) unknown future observations with a specified probability are derived. Our simultaneous intervals are based on two types of probability inequalities, i.e. the Bonferroni‐ and product‐types. These differ from the marginal intervals in that they take into account the correlation structure between the forecast errors. For the forecasting methods commonly used with seasonal time series data, we show how to construct forecast error correlations and evaluate, using an example, the simultaneous and marginal prediction intervals. For all the methods, the simultaneous intervals are accurate with the accuracy increasing with the use of higher‐order probability inequalities, whereas the marginal intervals are far too short in every case. Also, when L is greater than the seasonal period, the simultaneous intervals based on improved probability inequalities will be most accurate.
Quasi‐rational expectations: Experimental evidence
Authors: Nelson Robert G. , Bessler David A. 
Published: July 2007

AbstractThe theory of quasi‐rational expectations was tested under the controlled conditions of the economics laboratory. Five experiments were conducted with a variety of stochastic processes. In each experiment, subjects produced one‐step‐ahead forecasts of the variable generated by a Monte Carlo process. Comparisons of the performance of an aggregate of subjects' forecasts versus an ARIMA model showed that for relatively simple series (such as those generated by autoregressive processes of first or second order) the aggregate forecast was indistinguishable from that of the model. These results lend support to the theory that forecasts from an ARIMA model can serve as substitutes for aggregate expectations in macroeconomic policy models under some conditions.
On the sign of the optimal combining weights under the error‐variance minimizing criterion
Authors: Liang Kuo‐Yuan 
Published: July 2007

AbstractBuilding on the well‐known measure of the optimal combining weights under the error‐variance minimizing criterion, this note has extended the sign‐determination rule to the case of combining more than two competing forecasts. The algebraic rule derived provides a quick way to check the sign of each combining weight without directly comparing the correlation and variances of individual forecasting errors.