bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal and secular variations of sunshine duration and natural seasons in Japan
Authors: Inoue Tomoshige , Matsumoto Jun 
Published: August 2003

AbstractSeasonal transitions of sunshine duration and their secular changes in Japan are investigated for the period 1951–2000, and the influence of climatic variations on seasonal weather tendencies is discussed. Two seasons with little sunshine in the Baiu and the Akisame seasons are recognized in central and western Japan (CW Japan). In northern Japan, however, only one season with little sunshine in summer is seen. Another season with little sunshine is recognized for the Sea of Japan side and the Southwest Islands during the winter monsoon season.The sunshine duration from spring to autumn in northern Japan decreased in the late 1980s and the 1990s, and the period of little sunshine in summer has become longer since the mid 1980s. In CW Japan, sunshine in late spring in the 1950s and the early 1960s was less than that in other years. A rapid increase in sunshine duration which corresponds with the end of the Baiu rainy season has been delayed since 1980. The period in midsummer with little sunshine has also appeared more frequently than it did before 1980. In the Southwest Islands, sunshine duration has been decreasing almost all through the year. When comparing the differences between the Sea of Japan side and the Pacific Ocean side in winter, the sunshine contrast between them has intensified recently.By using sunshine duration, an objective classification of six natural seasons in CW Japan is conducted. Then, the long‐term change of seasonal march in CW Japan is investigated. The end dates of the Baiu season after 1980 have been delayed by about 5 days compared with those before 1980. From the viewpoint of sunshine contrasts between the Sea of Japan side and the Pacific Ocean side, the winter monsoon season in Japan has become longer in recent years, even under the warming trend of winter temperature. Copyright © 2003 Royal Meteorological Society
Urbanization and seasonal temperature trends: observational evidence from a data‐sparse part of North America
Authors: Englehart Phil J. , Douglas Arthur V. 
Published: August 2003

AbstractViewed from the continental or hemispheric perspective, the evidence of warming trends in surface temperatures continues to accumulate. Here, we focus on the detection of seasonal temperature trends at regional and sub‐regional space scales. The study region is transnational, extending from the border areas of New Mexico and Texas in the USA, southward into the altiplano of north central Mexico. The analysis considers maximum and minimum temperature records (1941–2000) from 21 stations located in a variety of land‐use environments ranging from large urban settings to rural areas. The analysis demonstrates that a significant part of the variability in minimum temperatures for stations located in large urban areas is captured by positive linear trend, and thus is likely associated with rapid urbanization within the region. A similar, but comparatively minor, urban effect is also apparent in the maximum temperature records for the warm season (June–September). Aside from the urban influence, the most consistent feature emerging from the analysis is the tendency for station records to exhibit a recent (post—1970) warming trend. It is present across all place sizes, i.e. from large urban to rural stations, and is particularly pronounced for cool‐ and warm‐season minimum temperatures and for warm‐season maximum temperatures. This behaviour generally mirrors the temperature trends detected on continental and hemispheric space scales, and thus the onset of this warming regime is broadly consistent with documented changes in large‐scale climate modes such as the North Atlantic oscillation and the Atlantic multi‐decadal oscillation. Copyright © 2003 Royal Meteorological Society
The annual cycle and interannual variability of atmospheric pressure in the vicinity of the North Pole
Authors: Cullather Richard I. , Lynch Amanda H. 
Published: August 2003

AbstractA comparison of National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis six‐hourly sea‐level pressure data with former Soviet drifting station observations over the central Arctic Basin reveals high monthly correlations throughout the period 1950–91, but also a preferred winter season negative bias of about 1.4 hPa. Using the reanalysis, supplemented by Arctic Ocean Buoy Program fields and in situ observations, a generalized depiction of the annual cycle of pressure fields over the Arctic may be constructed. Above the Canada Basin–Laptev Sea side of the Arctic, the annual cycle of surface pressure is dominated by the first harmonic, which has an amplitude of about 5 hPa and maximum pressure occurring in March. Along the periphery of northern Greenland and extending to the North Pole, a weak semiannual cycle is found in surface pressure with maxima in May and November. The presence of the semiannual variation over time is highly variable.Dynamically, this progression of the annual cycle may be attributed to the transfer of atmospheric mass from Eurasia and into the Canadian Archipelago in spring and the reverse condition in autumn. Over the central Arctic Basin, springtime pressure increases result from an enhanced poleward mass transport from Eurasia. An increase of equatorward transport over the Canadian Archipelago in May and June results in central Arctic pressure decreases into summer. A less distinct temporal separation between the poleward Canadian transport and the equatorward Eurasian transport results in the weaker second pressure maximum in autumn.On interannual time‐scales, atmospheric mass over the central Arctic is exchanged with the storm track centres of action in the North Atlantic and North Pacific. In particular, the large decrease in central Arctic Basin sea‐level pressure during the late 1980s is due to a large transfer of atmospheric mass into the North Pacific. Copyright © 2003 Royal Meteorological Society
The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part I: Literature evaluation and thermodynamic calculations on phase stabilities
Authors: Bender R. , Schütze M. 
Published: August 2003

AbstractIn several high temperature processing environments the presence of chlorine may significantly reduce the life‐time of the components. Although metallic materials have been widely used under such conditions there is still a need for data on the role of the different alloying elements in commercial alloys. In the present work this role was investigated in detail at temperatures between 650 and 1000°C in synthetic air containing up to 2 vol.% Cl2. Before starting the experimental investigation a detailed literature evaluation on chlorine high temperature corrosion was performed followed by a thermodynamic assessment of the stability and the partial pressures of the phases formed by the reaction between alloy and environment. The results of this “theoretical approach” are presented in the following first part of the publication while the experimental work will be reported in the second part appearing in a later issue of this journal. Already the results of the “theoretical approach” yield a clear picture of which alloying elements play a detrimental role and which elements are beneficial. These results can be used as a tool for a general assessment of metallic alloys with regard to their performance in oxidizing/chloridizing high temperature environments. In the second part of this work the results from this “theoretical approach” will be compared with the behavior of 14 commercial materials, where the content of the major alloying elements was varied in a systematic manner.
The influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91
Authors: Lindström R. , Johansson L.‐G. , Svensson J.‐E. 
Published: August 2003

AbstractThe influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91 is studied in the laboratory. Samples were exposed under carefully controlled air and flow conditions; the relative humidity was 95%, the temperature was 22.0°C and the concentration of CO2 was < 1 ppm or 350 ppm. Different amounts of sodium chloride (0–70 μg/cm2) were added before exposure. The corrosion products were analyzed by gravimetry, ion chromatography, X‐ray diffraction and scanning electron microscopy. Mass gain and metal loss results are reported. The combination of high humidity and NaCl is very corrosive towards AZ91. However, the NaCl‐induced corrosion is inhibited by ambient concentrations of CO2. Exposure in the absence of CO2 gives rise to heavy pitting, with brucite, Mg(OH)2, being the dominant corrosion product. In the presence of CO2 a layer of hydrated magnesium hydroxy carbonate, Mg5(CO3)4(OH)2 · 5 H2O forms. A tentative corrosion mechanism is presented that explains the behavior in the two environments.
Prediction of the remaining lifetime of stainless steels under conditions of stress corrosion cracking
Authors: Tandler M. , Vehovar L. , Doleček V. , Rotnik U. 
Published: August 2003

AbstractThe prediction of the lifetime of metal structures and equipment under conditions of stress corrosion is very complicated because of the complexity of this process of degradation. Recently a new method, based on the so‐called corrosion elongation curves, has been found, which can be used to predict the time to failure under these conditions. By upgrading of these curves (and thus obtaining Upgraded Corrosion Elongation Curves – UCEC's) it has been possible to obtain a precise definition of the time needed for the initiation of the corrosion crack, and for its stable growth. It is upon this basis that diagrams for the prediction of remaining lifetime (DPRL's) have been developed. DPRL's can also be used to predict the values of various critical parameters which have to be achieved if a stress corrosion crack is to occur.
Carbon and stainless steel in solutions of lithium nitrate in ammonia at moderate temperatures
Authors: Heard C. L. , Ayala R. 
Published: August 2003

AbstractThe lithium nitrate in ammonia solution has been proposed and demonstrated as a thermodynamically attractive working mixture for absorption heat pumps. A literature search failed to find corrosion studies of said solution. The corrosion of carbon and stainless steel in solutions of lithium nitrate in ammonia was studied for a series of concentrations and temperatures from 50 to 150°C. The materials studied were found to be suitable for construction of absorption heat pump process equipment for this working mixture.
Charakterisierung von Randentkohlungsvorgängen bei der Austenitisierung des Wälzlagerstahls 100Cr6. Teil 1: Korrelation zwischen Randschichteigenschaften und Kohlenstoff‐Tiefenverlauf
Authors: Gegner J. , Nierlich W. , Wilbrandt P.‐J. , Kirchheim R. , Öchsner A. 
Published: August 2003

AbstractDer Einfluss einer Randentkohlung bei der Austenitisierung des durchhärtenden Wälzlagerstahls 100Cr6 (SAE 52100) auf die Randschichteigenschaften des martensitisch durchgehärteten Werkstoffs wurde mittels Materialanalytik und Diffusionsrechnungen untersucht. Dazu wurde in zwei Proben nach definierter Wärmebehandlung die oberflächennahe Kohlenstoffverteilung mikrochemisch mittels Sekundärionenmassenspektrometrie (SIMS) bestimmt. In Teil 1 der vorliegenden Arbeit werden diese Konzentrationsprofile mit den Tiefenverläufen der Kleinlasthärte sowie der durch Röntgenbeugung gemessenen Eigenspannungen und Halbwertsbreiten ({211} α'‐Fe Beugungslinie) verglichen. Zusätzlich wurden Gefügeuntersuchungen durchgeführt. In Teil 2 wird ein auf der Finite‐Elemente‐Methode (FEM) beruhendes verfeinertes Kinetikmodell für eine diffusionsgesteuerte Reaktion auf die Randentkohlung angewendet, um die erhaltenen Kohlenstoffverteilungen zu beschreiben.
Charakterisierung von Randentkohlungsvorgängen bei der Austenitisierung des Wälzlagerstahls 100Cr6. Teil 2: Modellierung des Kohlenstoff‐Tiefenverlaufs mit Hilfe der Methode der Finiten Elemente
Authors: Gegner J. , Nierlich W. , Öchsner A. , Wilbrandt P.‐J. , Kirchheim R. 
Published: August 2003

AbstractDie quantitative Messung von Kohlenstoff‐Tiefenverläufen stellt eine wesentliche Voraussetzung zur werkstoffkundlichen Beurteilung von Randschichteigenschaften bei Entkohlungsvorgängen dar. Dies wurde in Teil 1 der vorliegenden Arbeit an zwei in unterschiedlich oxidierender Atmosphäre austenitiserten Proben aus durchhärtendem Wälzlagerstahl 100Cr6 (SAE 52100) durch abstandsabhängige Bestimmung der Härte, Eigenspannungen und röntgenographischen Halbwertsbreiten ({211} α’‐Fe Beugungslinie) gezeigt. In der Praxis ist es wichtig, Kohlenstoff‐Konzentrationsverläufe unter herrschenden Wärmebehandlungsbedingungen vorherzusagen oder darauf anhand von Profilmessungen zurückzuschließen. Deshalb stellt Teil 2 ein mit Hilfe der Finite‐Elemente‐Methode (FEM) entwickeltes Simulationswerkzeug vor, das auf einem verfeinerten Kinetikmodell für einen diffusionsgesteuerten Prozess beruht. Es berücksichtigt neben der Konzentrationsabhängigkeit des Diffusionskoeffizienten auch die entkohlungsbedingte Austenit‐Ferrit‐Phasenumwandlung, den zeitlich veränderlichen Einfluss der Verzunderung und variierende Atmosphärenverhältnisse. Die Interpretation der mittels Sekundärionenmassenspektrometrie (SIMS) in der Randschicht der beiden 100Cr6‐Proben sehr genau gemessenen Kohlenstoff‐Tiefenverläufe bestätigt die Anwendungsmöglichkeiten des neuen numerischen Werkzeugs.
Mikrostrukturelle Veränderungen von Magnesium‐Druckgusslegierungen nach langzeitiger thermischer Beanspruchung
Authors: Regener D. , Schick E. , Heyse H. 
Published: August 2003

AbstractDie Erweiterung des Anwendungsbereiches von Magnesium‐Druckgusslegierungen im Automobilbau erfordert die Entwicklung neuer Legierungen, aber auch die umfassende Beurteilung vorhandener Legierungen unter verschärften Beanspruchungsbedingungen. Unter derartigen Bedingungen ist auch der Einsatz bei höheren Temperaturen zu verstehen, bei dem ein Kriechen des Werkstoffs zum Versagen des Bauteils führen kann. Da die Gefügestabilität der Werkstoffe maßgeblich von der thermischen Belastung abhängt, werden im vorliegenden Beitrag die Legierungen AZ91, AM50 und AE42 einer 1000 h‐Langzeitglühung bei 150 °C und 200 °C unterworfen und die Veränderungen des Gefüges und der Härte im Vergleich zum druckgegossenen Ausgangszustand untersucht.Die Ergebnisse zeigen starke Unterschiede in der Gefügestabilität der Legierungen AZ91 und AM50 einerseits und der Legierung AE42 andererseits. In den Legierungen AZ91 und AM50 wird infolge des Langzeitglühens bei 150 °C vor allem eine intensive Ausscheidung von Mg17Al12 aus der Al‐reichen eutektischen α‐Phase, bei 200 °C darüber hinaus auch die Koagulation und Vergröberung dieser Ausscheidungen beobachtet, die mit einer Erweichung des Werkstoffes einhergehen. In der Legierung AE42 sind die Veränderungen im Ausscheidungszustand weniger intensiv und führen unter den genannten Untersuchungsbedingungen noch nicht zur Gefügeerweichung.
Practicability and Limitations of Finite Element Simulation of the Dilation Behaviour of Coronary Stents
Authors: Stolpmann J. , Brauer H. , Stracke H.‐J. , Erbel R. , Fischer A. 
Published: August 2003

AbstractAfter first implantation of a metallic stent into cardiac vessels in 1986 stent implantation has become a standard technique for treatment of coronary heart disease. During implantation of balloon‐expandable stents, the structure of the stent undergoes high plastic deformation. Despite the fact, that stents are used for more than 15 years nearly no information about the mechanical and micro structural process during dilation are known. The present paper presents a detailed study and comparison of the experimental and the simulated expansion behaviour of metallic stents. Used material models are discussed and crystallographic details are presented. Dilation curves describe the behaviour of balloon‐expandable coronary stents. The dilation behaviour depends on both the materials properties and the design of the stent. A numerical simulation of the dilation process by means of FE is suitable. A comparison of the experimental measurement and the numerical simulation demonstrates, that a Cauchy stress‐strain material model should be used for numerical simulations. A local failure criterion is introduced, which considers void initiation as a criterion for mechanical failure.
Werkstoffmodell zur Berechnung der mittleren Fließspannung bleihaltiger Messinge bei hohen Temperaturen
Authors: Hofmann U. 
Published: August 2003

AbstractEin einfaches Modell der Hochtemperaturumformung Pb‐haltiger Messinge wird vorgestellt. Es basiert auf Warmstauchversuchen, die mit den Legierungen Wieland‐Z36 (CuZn36Pb2As) und Wieland‐Z38 (CuZn40Pb2) durchgeführt wurden. Dabei wurden ein Temperaturbereich von 600 °C bis 850 °C und Umformgeschwindigkeiten zwischen 0,1/s und 10/s experimentell abgedeckt. Diese Parameter sind für die Praxis relevant, denn sie treten bei der Warmumformung von Messing – z. B. beim Gesenkschmieden – auf. Die Gültigkeit des Modells wird an anderen CuZnPb‐Legierungen überprüft.Das Modell beschreibt die mittlere Fließspannung eines Pb‐haltigen Messings als Funktion der Temperatur und der Umformgeschwindigkeit. Der Werkstoff wird dabei als Verbund aus α‐ und β‐Phase aufgefasst. Die Phasen zeichnen sich durch unterschiedliche Umformeigenschaften aus. Ihre Volumenanteile sind die für die Warmumformung relevanten Gefügeparameter. Sie können aus dem Gleichgewichtszustandsdiagramm entnommen werden und hängen von der Temperatur und der chemischen Zusammensetzung der Legierung ab. Die Volumenanteile der Phasen bestimmen, welche Gefügekomponente das Verformungsverhalten des Gesamtverbundes dominiert.
Cast Pipe Joints of Fe‐15Mn‐5Si‐8Cr‐5Ni‐0.25C Shape Memory Alloy with High Carbon Content
Authors: Zhao M. , Li J. C. , Jiang Q. 
Published: August 2003

AbstractAbstract: The cast pipe joint of the Fe‐15Mn‐5Si‐8Cr‐5Ni‐0.25C alloy was manufactured (the numbers in the composition denote the weight percentage of the elements while the weight percentage of Fe is the balance). The corresponding microstructure and shape memory effect are compared with those of a forged alloy. The results show that the cast joint has a good shape memory effect and may be industrially applied while the cast joint keeps jointing under a tensile force of 20 kN and a sealing pressure of 5 MPa. Moreover, it is found that the addition of nitrogen in the alloy doesn’t evidently improve the shape memory effect of the alloy.
Object‐oriented three‐dimensional hybrid grid generation
Authors: Athanasiadis A. N. , Deconinck H. 
Published: August 2003

AbstractAn algorithm is described for the generation of hybrid grids suitable for viscous computations around complex geometries. The definition of the geometry is given by the ISO standard STEP format. The grid generation is based on a hierarchical approach. The user‐specified parameters are given on all basic STEP entities and the definition is consistent across the complete geometry. Semi‐structured layers of prismatic cells are generated, starting from the viscous boundaries of the domain. The remaining volume is filled by an unstructured Delaunay algorithm with frontal node creation. Complex models have been successfully gridded, however, more testing is needed. Copyright © 2003 John Wiley & Sons, Ltd.
Parallel Delaunay mesh generation kernel
Authors: Chrisochoides Nikos , Nave Démian 
Published: August 2003

AbstractWe present the results of an evaluation study on the re‐structuring of a latency‐bound mesh generation algorithm into a latency‐tolerant parallel kernel. We use concurrency at a fine‐grain level to tolerate long, variable, and unpredictable latencies of remote data gather operations required for parallel guaranteed quality Delaunay triangulations. Our performance data from a 16 node SP2 and 32 node Cluster of Sparc Workstations suggest that more than 90% of the latency from remote data gather operations can be masked effectively at the cost of increasing communication overhead between 2 and 20% of the total run time. Despite the increase in the communication overhead the latency‐tolerant mesh generation kernel we present in this paper can generate tetrahedral meshes for parallel field solvers eight to nine times faster than the traditional approach. Copyright © 2003 John Wiley & Sons, Ltd.
A method for hexahedral mesh shape optimization
Authors: Knupp Patrick M. 
Published: August 2003

AbstractMethods for improving the quality of all‐hexahedral unstructured meshes by node‐movement strategies have, until recently, been lacking. Laplacian smoothing, while easily implemented and well‐known, fails to guarantee improvement of mesh quality and may result in inverted elements where none existed before. A method for improving unstructured hexahedral mesh shape‐quality that guarantees untangled elements is proposed. The method is based on optimization of an objective function built from the quality of individual hexahedral elements. The shape‐quality measure for hexahedral elements is based on the condition number of a set of Jacobian metrics associated with the element. The theory of the condition number quality metric and of the objective function are reviewed. A numerical optimization procedure to find the improved‐quality mesh is described. The purpose of this paper is to demonstrate the robustness of the method. We do so by giving a realistic example. The method has also been successfully applied to dozens of meshes on complex geometries. Published in 2003 by John Wiley & Sons, Ltd.
Interpolating and meshing 3D surface grids
Authors: Laug P. , Borouchaki H. 
Published: August 2003

AbstractIn the boundary representation (B‐Rep) model, a three‐dimensional (3D) surface is defined by a set of ‘simpler surfaces’ called ‘patches’. Although there are many different ways to specify a patch, a common case is that of a 4‐sided patch represented by a structured grid of points. For instance, this kind of data can easily be obtained from a CAD system, as it is the mapping of regularly spaced points in a rectangular parametric domain. It can also be obtained from some particular 3D scanning devices. Non‐rectangular topologies may also be encountered, for instance the 3‐sided patch which can be considered as a degenerate case of the 4‐sided patch (one side being of zero length). In this paper, we use the Coons method to build a surface interpolating the vertices of such a grid. The continuity of this parameterization makes it suitable for our indirect approach to surface meshing, which is generally based on the generation of an anisotropic mesh in the parametric space. Moreover, the indirect approach has been extended to the construction of anisotropic geometric surface meshes in 3D space, allowing an accurate geometric representation of the surface with a minimal number of elements. Several examples demonstrate the capabilities of this method. Copyright © 2003 John Wiley & Sons, Ltd.