bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational study of unsteady turbulent flows around oscillating and ramping aerofoils
Authors: Barakos G. N. , Drikakis D. 
Published: April 2003

AbstractThe aim of this work is to computationally investigate subsonic and transonic turbulent flows around oscillating and ramping aerofoils under dynamic‐stall conditions. The investigation is based on a high‐resolution Godunov‐type method and several turbulence closures. The Navier–Stokes and turbulence transport equations are solved in a strongly coupled fashion via an implicit‐unfactored scheme. We present results from several computations of flows around oscillating and ramping aerofoils at various conditions in order to (i) assess the accuracy of different turbulence models and (ii) contribute towards a better understanding of dynamic‐stall flows. The results show that the employed non‐linear eddy‐viscosity model generally improves the accuracy of the computations compared to linear models, but at low incidence angles the Spalart–Allmaras one‐equation model was found to provide adequate results. Further, the computations reveal strong similarities between laminar and high‐Reynolds number dynamic‐stall flows as well as between ramping and oscillating aerofoil cases. Investigation of the Mach number effects on dynamic‐stall reveals a delay of the stall angle within a range of Mach numbers. Investigation of the reduced frequency effects suggests the existence of an (almost) linear variation between pitch rate and stall angle, with higher slope at lower pitch rates. The pitch rate affects both the onset of dynamic‐stall as well as the evolution of the associated vortical structures. Copyright © 2003 John Wiley & Sons, Ltd.
An efficient method for capturing free boundaries in multi‐fluid simulations
Authors: Xiao F. , Ikebata A. 
Published: April 2003

AbstractAn easy‐to‐use front capturing method is devised by directly solving the transport equation for a volume of fluid (VOF) function. The key to this method is a semi‐Lagrangian conservative scheme, namely CIP_CSL3, recently proposed by the author. In the CIP_CSL3 scheme, the first‐order derivative of the interpolation polynomial at each cell centre is used to control the shape of the reconstructed profile. We show in the present paper that the first‐order derivative, which plays a crucial role in reconstructing the interpolation profile, can also be used to eliminate numerical diffusion. The resulting algorithm can be directly used to compute the VOF‐like function and retain the compact thickness of the moving interface in multi‐fluid simulations. No surface reconstruction based on the value of VOF function is required in the method, which makes it quite economical and easy to use. The presented method has been tested with various interfacial flows including pure rotation, vortex shearing, multi‐vortex deformation and the moving boundaries in real fluid as well. The method gives promising results to all computed problems. Copyright © 2003 John Wiley & Sons, Ltd.
Changes in the surface water hydrologic characteristics of an endoreic basin of northern Mexico from 1970 to 1998
Authors: Viramontes D. , Descroix L. 
Published: April 2003

AbstractThe western Sierra Madre is the main water‐providing area of northern Mexico. However, most of this mountain range has suffered a progressive degradation of soils and vegetation due to overgrazing and deforestation, for four or five decades. The objective of this study is to determine the impacts of these changes on water balance and hydrodynamic basin behaviour.The hydrological data of two basins (the Sextin basin, 4660 km2 and the Ramos basin, 7130 km2) of this area were analysed. Annual runoff coefficients have not changed. Therefore, other indices were used to determine changes in the streamflow regime:

an index of irregularity of daily discharge;

the separation of flood flow and base flow;

the lag time of the watersheds;

the baseflow recession index;

the two‐day recession index.

Some changes were noticeable at the basin scale in the water balance of the catchments:

the ratio of the flood runoff coefficient to the base runoff coefficient increased from the 1970s to the 1990s;

the basin lag time decreased 2·1% in the Ramos basin and 6·1% in the Sextin basin;

the two‐day recession index and the baseflow recession index increased, reflecting a more rapid decrease of streamflow after the peak flow;

the mean annual runoff coefficient and the irregularity as estimated by the index used here showed no significant evolution.

The convergence of such observations confirms that dramatic changes in the evolution of water resources in the near future in this area are to be expected, if the current land use is not strongly modified. Water management and dam operation would also be seriously affected. Copyright © 2003 John Wiley & Sons, Ltd.
Exportation of organic carbon from the Amazon River and its main tributaries
Authors: Moreira‐Turcq Patricia , Seyler Patrick , Guyot Jean Loup , Etcheber Henri 
Published: April 2003

AbstractAs part of a joint Brazilian–French project, entitled ‘Hydrology and Geochemistry of the Amazon Basin’, we carried out a seven‐year study (1994–2000) on the distribution, behaviour and flux of particulate and dissolved organic carbon in the Amazon River and its main tributaries (the Negro, Solimões, Branco, Madeira, Tapajós, Xingú and Trombetas rivers).The concentrations of particulate and dissolved organic carbon varied from one river to another and according to the season, but dissolved organic carbon (DOC) always accounted for about 70% of the total organic carbon (TOC). The mean concentration of dissolved organic carbon was 6·1 mg l−1in the Madeira River, 5·83 mg l−1in the Solimões River and 12·7 mg l−1in the Negro River. The percentage in weight of the particulate organic carbon decreased as the concentration of suspended matter increased. The Solimões River contributed the most carbon to the Amazon River: about 500 kg C s−1during the high water period and about 300 kg C s−1during the low water period. However, the temporal variations in organic carbon in the Amazon River (i.e. downstream of Manaus) are basically controlled by inputs from the Negro River and its variations. The Negro River does not produce a simple dilution effect. During the high water period (between March and August) the TOC flux, calculated as the sum of the Solimões, Negro and Madeira tributaries, was about 5·7 × 1013g C yr−1, whereas during the low water period (between September and February) the TOC flux was about 2·6 × 1013g C yr−1.The mean annual flux of TOC at Óbidos (the final gauging station upstream of the estuary) was about 3·27 × 1013g C yr−1(i.e. 32·7 ± 3·3 Tg yr−1). Of this, the flux of DOC represents about 2·7 × 1013g C yr−1and the flux of particulate organic carbon (POC) represents about 0·5 × 1013g C yr−1. The mean annual input of TOC by all tributaries (Negro, Solimões, Madeira, Trombetas, Tapajós and Xingú) was about 2·8 × 1013g C yr−1. When we compared this input with the output recorded at Óbidos (3·27 × 1013g C yr−1), we found that the amount of organic carbon increased (about 0·4 × 1013g C yr−1). This shows that other important sources of organic carbon exist in the lower reaches of the Amazon River. These inputs can be attributed to the adjacent floodplain lake system, called ‘várzea’. Copyright © 2003 John Wiley & Sons, Ltd.
Carbon and metal concentrations, size distributions and fluxes in major rivers of the Amazon basin
Authors: Benedetti Marc F. , Mounier Stephane , Filizola Naziano , Benaim Jean , Seyler Patrick 
Published: April 2003

AbstractThe chemical composition of the Amazon River results from the mixing of two water types: black water and white water. On‐site fractionation by sequential tangential ultrafiltration (STUF) was used to differentiate transported organic carbon and to determine the distribution and association of major and trace elements with different size fraction of the organic carbon (OC). Several sampling campaigns (1994–1996) allow a monthly quantification of particulate (OCP, MeP), colloidal (OCC, MeC) and dissolved (OCD, MeD) organic carbon and metal ions inputs. In white rivers the OC is mainly concentrated in the low molecular weight fraction (OCD < 5000 D) while in black rivers most of the OC is in the heavier molecular weight fractions (OCP and OCC > 5 kDa). For Mg, Ca and K, 50% of the total amount of each element is found in fraction MeD while 15% and 35% are found in fractions MeC and MeP, respectively. Al and Fe are in the particulate fraction at 99% of the total metal concentration for all river samples. This work emphasizes the coagulation processes and the sink for elements in the mixing zone. These physicochemical transformations of the organic matter vary seasonally. The changes happen during the transition periods: before high‐level waters and before low‐level waters. By way of flux measurement, a seasonal carbon loss was observed. The estimated annual organic carbon flux of the Amazon at Òbidos is 28 × 106 t. At the same time, an average of 9 × 106 t of organic carbon per year is retained in the reach between Manaus and Òbidos, probably via coagulation processes. Copyright © 2003 John Wiley & Sons, Ltd.
The socioeconomic roots of conflict in the Caucasus
Authors: Glinkina Svetlana P. , Rosenberg Dorothy J. 
Published: April 2003

AbstractWe argue that the conflicts in the Caucasus are the result of the abrogation by the elite of the earlier, Soviet era social contract. This process was accompanied by the collapse of the formal economy; evidenced by huge national income compression, falling public goods provision, and growing inequality and poverty. In the absence of state provision of basic amenities and governance, ordinary people are compelled to fall back on kinship ties. Declining standards of governance facilitate state‐sponsored corruption and criminality in a setting where the shadow economic activity is increasingly important to individual survival strategies. Oil pipelines and the right to control the transit of goods both legal and illegal also underlie conflict in the region. Criminality has replaced ethnicity as the major motivation for conflict and conflict per se has become a lucrative source of income. Copyright © 2003 John Wiley & Sons, Ltd.
The political economy of Malaysian federalism: economic development, public policy and conflict containment
Authors: K. S. Jomo , Hui Wee Chong 
Published: April 2003

AbstractConflicts within the Malaysian federation have been rooted in socio‐economic disparities and the struggle for control of natural resource rents, which state governments previously had exclusive control over, as originally provided for by the federal constitution. The advance of fiscal centralization since then has also aggravated federal–state tensions, which have been relatively ignored due to the long‐standing Malaysian pre‐occupation with inter‐ethnic tensions. Inter‐regional resource transfers and central fiscal and political dominance have been used to undermine the more independent state governments, especially those held by opposition parties. While the federal government is clearly dominant, central control over the state governments has varied, especially in Sabah and Sarawak, with the continued hegemony of the national ruling coalition depending on successfully combining the carrot with the stick. Copyright © 2003 John Wiley & Sons, Ltd.
Economic aspects of the Palestinian—Israeli conflict: the collapse of the Oslo Accord
Authors: Naqib Fadle M. 
Published: April 2003

AbstractSince October 2000 Israel and the Palestinians of the West Bank and Gaza Strip have become entangled in a bloody confrontation. This paper focuses on the economic relationship between the Israeli economy and the Palestinian economy of the West Bank and Gaza Strip, and the ways in which this has contributed to the collapse of the Oslo Accord. The paper finds that Israeli policies have distorted and weakened the Palestinian economy, particularly in the areas of trade (dependence upon one major trade partner), taxation (loss of revenues to finance development spending) as well as in the labour market (controls on labour flows) and in Palestinian access to land (including land confiscation). As a result, besides income compression, poverty and unemployment have risen in the Palestinian territories. Two central issues of the conflict need to be addressed: the Palestinian right to sovereignty over their land and their right to free their economy from colonial dependency on Israel. Copyright © 2003 John Wiley & Sons, Ltd.
Knowledge management in the professional organization: a model with application to CMG software testing
Authors: Kerkhof Cesanne , Ende Jan van den , Bogenrieder Irma 
Published: April 2003

AbstractKnowledge and the management of knowledge are recognized as becoming more important to modern organizations. Unfortunately, modern literature is not clear on the ways to implement knowledge management in practice. This article presents a model for this purpose, dedicated to professional organizations. Present theories about knowledge, learning organizations and knowledge transfer form the basis of the model. The model is applied to CMG Software Testing. Copyright © 2003 John Wiley & Sons, Ltd.
The facilitating factors for organizational learning: bringing ideas from complex adaptive systems
Authors: Chiva‐Gómez Ricardo 
Published: April 2003

AbstractThe importance of the factors that facilitate organizational learning have traditionally been outlined in the literature. However, there is no agreement about what the essential facilitating factors are, as each author emphasizes different features. Complexity science is increasingly being used by researchers and practitioners to improve their understanding of organizations. This exploratory study tries to determine the essential facilitating factors for organizational learning, and demonstrate the importance of the ideas from complex adaptive systems (CAS) to it. In order to do this, we put forward a comparative case study of four heterogeneous companies from the Spanish ceramic tile sector in which we analyzed the facilitating factors for organizational learning, by relating them with ideas from CAS. As a result, we determined that the five attributes suggested by CAS to facilitate organizational learning were present in the innovative companies, which had the most organizational learning facilitating factors, and three of them were only present in the company with the highest performance and the most innovative approach: individuals' relationship with the environment; cultural diversity; and state of equilibrium between formal and informal structures. Copyright © 2003 John Wiley & Sons, Ltd.
Cholinergic nicotinic receptors: Competitive ligands, allosteric modulators, and their potential applications
Authors: Romanelli M. Novella , Gualtieri Fulvio 
Published: April 2003

AbstractDiscovery of the important role played by nicotinic acetylcholine receptors (nAChRs) in several CNS disorders has called attention to these membrane proteins and to ligands able to modulate their functions. The existence of different subtypes at multiple levels has complicated the understanding of this receptor's physiological role, but at the same time has increased the efforts to discover selective compounds in order to improve the pharmacological characterization of this kind of receptor and to make the possible therapeutical use of its modulators safer. This review focuses on the structure of new ligands for nAChRs, agonists, antagonists and allosteric modulators, and on their possible applications. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 4, 393–426, 2003
Novel antiplasmodial agents
Authors: Go Mei‐Lin 
Published: April 2003

AbstractThe morbidity and mortality associated with malaria have spurred efforts to find novel antimalarial agents with improved potency and selectivity. Leads for agents continue to be obtained from natural sources (plants and microorganisms) and chemical syntheses. Screening of commercial or specialized databases have also yielded promising leads. The structural diversity of compounds with good (micromolar and lower) activity point to the considerable tolerance for different structural elements in the “antimalarial pharmacophore.” It may also be a reflection of the varied targets present in the plasmodia. The challenge in malaria chemotherapy is to find safe and selective agents whose potencies will not be compromised by plasmodial resistance. Modification of potential leads should also aim at improving “drug‐like” character, viz. to ensure acceptable oral bioavailability. A review of the literature shows that there is a growing trend towards the development of target‐specific antimalarial agents (for example, agents inhibiting plasmodial farnesyl transferase, cyclin dependent kinases, proteases, choline transport). An increasing number of reports focus on the development of chemosensitizers, agents that are capable of reversing plasmodial resistance. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 4, 456–487, 2003
On the fractionation of linear polyethylene
Authors: Salovey R. , Hellman M. Y. 
Published: April 2003

AbstractFibrillar crystals of polyethylene are prepared by stirring solutions of the polymer in xylene at elevated temperatures. Extraction of these crystals with xylene at controlled temperatures is a convenient method of preparing narrow fractions of linear polyethylene of molecular weights below 105. Higher molecular weight fractions were readily obtained by column fractionation but not by the extraction of fibrillar crystals.
Determination of rubber dynamic properties using a sinusoidal vibrator and weighted specimen
Authors: Frazee J. D. , Tucker J. 
Published: April 2003

AbstractA test procedure is described for determining the dynamic response of highly loaded elastomers. This consists of weighted column vibration specimen monitored with accelerometers. Results on three natural rubber and three SBR standard formulations are briefly summarized. The effect of temperature and solids loading on the transmissibility and resonant frequency is discussed. Certain features of the tests and the availability of both simplified and complex (general) analyses recommend it for obtaining a broader knowledge of the dynamic mechanical properties of loaded vulcanizates.
A light‐scattering photometer for the angular range 6–170°
Authors: Meyerhoff G. , Moritz U. , Darskus R. L. 
Published: April 2003

AbstractA light‐scattering phtometer for measurements on solutions in the angular range 6–170° is described. Its use is illustrated by the determination of the average molecular weights Mw and Mn, as well as the gyration radii 〈r2〉z1/2 and 〈r2〉n1/2, on a polystryene fraction.
Polymerization of 3‐vinylpyrene with Ziegler‐Natta catalyst
Authors: Tanikawa Kiyoshi , Kusabayashi Shigekazu , Hirata Hirotaka , Mikawa Hiroshi 
Published: April 2003

AbstractUsing a Ziegler‐Natta catalyst, we obtained a polymer of 3‐vinylpyrene having large π‐electron systems as pendant groups. The conversion was highest at AlEt3/TiCl4 = 1/1, being ca. 90%. It was lower with TiCl4 alone, and was also reduced down to ca. 30% at Al/Ti = 7/1. The conversion exceeded 80% after only 7 hr. at Al/Ti = 2/1. This polymer has a melting point of 214°C. determined by a polarizing hot‐stage microscope examination. X‐ray examination showed that this polymer is crystalline, although rather poor. The polymer is soluble in many solvents. From the similarity of ultraviolet absorption spectra of 3‐ethylpyrene and polyvinylpyrene prepared by benzoyl peroxide (BPO), TiCl4, AlEt3–TiCl4, this polymer is believed to have a linearly combined chain structure with a large pendant pyrene nucleus and to have no crosslinking at all.
A novel copolymerization reaction
Authors: Meyers R. A. , Wilson E. R. 
Published: April 2003

AbstractA new addition polymerization reaction is described which involves the copolymerization of sulfur dichloride or sulfur monochloride with a diolefin. Sulfur dichloride copolymerizes with bis(1,2,3,6‐tetrahydrophthalimide) (A) to form poly[N,N′‐m‐phenylenebis(3,4‐dicarboxy‐6‐chlorocyclohexyl) sulfide imide] (I). Sulfur monochloride copolymerizes with A to form poly[N,N′‐m‐phenylenebis(3,4‐dicarboxy‐6‐chlorocyclohexyl) disulfide imide] (II). The polyimides, I and II were characterized by elemental analysis, infrared spectroscopy, and inherent viscosity. The mechanism of polymerization is discussed.
Estimation of the ceiling temperature for the polymerization of acetone
Authors: Waywell David R. 
Published: April 2003

AbstractThe thermodynamics of the polymerization of acetone through the carbonyl group has been investigated in an attempt to find the limiting experimental conditions for producing high molecular weight polymer. Approximate values for the entropy and enthalpy of polymerization were estimated empirically from data published on polyolefins and polyacetals. A low negative heat of polymerization (ΔHp = −2.4 kcal mole.−t) rather than a high negative entropy (Δ Sp = −45 cal mole−1 (deg K)−1) was considered to be the controlling influence in the polymerization. From these values, a ceiling temperature of –220°C was calculated for the reaction of gaseous acetone to form amorphous polyacetone.
The cationic polymerization of “endo” ‐dicyclopentadiene, 1,2–dihydro‐“endo” ‐dicyclopentadiene and 9,10–dihydro‐“endo” ‐dicyclopentadiene
Authors: Cesca Sebastiano , Priola Aldo , Santi Giuliano 
Published: April 2003

AbstractThe polymerizations of “endo” ‐dicyclopentadience (I), 1,2–dihydro‐“endo”‐dicyclopentadiene (II) and 9,10–dihydro‐“endo”‐dicyclopentadiene (III), initiated by cationic systems, have been investigated under different conditions. Linear polymers with M̄n in the range 1300–4500 have been obtained with (I) and (II): poly‐(I) shows less than one double bond for structural unit. In the case of (III) only oligomers were observed. Copolymerization runs show a reactivity of (III) lower than (II). Spectroscopic and chemical analyses of the polymers obtained indicate that besides the norbornene double bond, also the cyclopentenic unsaturation, present in (I) and (III), reacts.Some evidences for a hydride shift in cyclopentence ring, after the attack of the initiator, were collected. In the case of poly‐(I) the main enchainment resulted from the norbornene double bond opening, but about 30% of nortricyclene repeating unit was also observed.
Thermal characterization of polyester–melamine coating matrices prepared under nonisothermal conditions
Authors: Gamage N. J. W. , Hill D. J. T. , Lukey C. A. , Pomery P. J. 
Published: April 2003

AbstractThermal analysis methods (differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis) were used to characterize the nature of polyester–melamine coating matrices prepared under nonisothermal, high‐temperature, rapid‐cure conditions. The results were interpreted in terms of the formation of two interpenetrating networks with different glass‐transition temperatures (a cocondensed polyester–melamine network and a self‐condensed melamine–melamine network), a phenomenon not generally seen in chemically similar, isothermally cured matrices. The self‐condensed network manifested at high melamine levels, but the relative concentrations of the two networks were critically dependent on the cure conditions. The optimal cure (defined in terms of the attainment of a peak metal temperature) was achieved at different oven temperatures and different oven dwell times, and so the actual energy absorbed varied over a wide range. Careful control of the energy absorption, by the selection of appropriate cure conditions, controlled the relative concentrations of the two networks and, therefore, the flexibility and hardness of the resultant coatings. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1603–1621, 2003