bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axial compressor performance modelling with a quasi-one-dimensional approach
Authors: White N. M. , Tourlidakis A , Elder R. L. 
Published: August 2003

This paper describes a technique for the numerical modelling of axial compressors using the simplest form of representation—a mean-line one-dimensional method. Although this type of flow analysis is a gross simplification of a complex three-dimensional system, which can now be modelled more accurately by many of today's computational fluid dynamics (CFD) packages, it does offer the advantages of simple input requirements and fast convergence times. These factors were major considerations when choosing a prediction method to be employed within an optimization program developed at Cranfield for the optimization of stator vane stagger angles, where detailed stage data were not required. The objective was to develop a technique capable of simply modelling the flow in multistage compressors to provide performance data including overall pressure ratio, efficiency and flow range at various speeds, as well as providing interblade data so that restaggering of blades could be accounted for. The salient issues presented here deal firstly with the construction of the compressor model and its incorporation into a FORTRAN program. A discussion of the results then follows, where four very different compressors have been modelled. Finally, the stability limit (or surge point) prediction methods are reviewed. Results have shown that consistent agreement can be obtained with such a performance prediction model, providing the loss and deviation correlations used are applicable to the blade profiles. It was also apparent that the two simplistic methods of surge prediction, which relied upon either stage or overall characteristic gradients, gave better agreement than the more rigorous discrete stage-to-stage model. This was thought to be a result of the continuous nature of the empirical rules utilized, which predict a smooth stage characteristic and hence falsely delay the estimated instability point.
Wear performance of polytetrafluoroethylene-metal coatings in rolling/sliding line contact
Authors: Akdogan G , Stolarski T. A. , Tobe S 
Published: August 2003

The study, presented in this paper, aims to shed some light on the effect of deposited polytetrafluorothylene (PTFE) on the tribological performance of Al bronze and Mo coatings in rolling/sliding contact conditions by using a two-disc machine. The experimental results revealed that both PTFE-Al bronze and PTFE-Mo coatings had outstanding wear and surface fatigue resistance. Although PTFE-Al bronze coatings had relatively better wear behaviour than PTFE-Mo coatings under both pure rolling and rolling/sliding conditions, both coatings had no significant surface damage after 1.2 × 106 load cycles. Optical microscopy and scanning electron microscopy studies suggest that metallic asperities in the coating matrix acted as the load carrier. PTFE was lost by an adhesive wear due to transfer film formation on the counter steel surface, which in turn provided good lubrication of the contact zone.
Modelling the early stage of spark ignition engine combustion using the KIVA-3V code incorporating an ignition model
Authors: Andreassi L , Cordiner S , Rocco V 
Published: August 2003

The evolution of early stages of homogeneous mixture combustion in spark ignition (SI) engines represents a critical period that greatly affects the whole combustion process. A proper description of this critical phase represents a major issue, which could strongly influence the overall model predictive capability (i.e. model ability to reproduce the real engine behaviour for a large range of operating conditions without any major tuning). Such requirements become even more important for the simulation of last-generation gasoline direct injection or lean stratified engines, where ignition could determine the functionality of the engine itself. In this paper, after a detailed analysis of the ignition physical process and its modelling issues, the predictive capability of the KIVA-3V code has been improved by substituting the original ignition procedure with a more detailed kernel evolution model based on the one presented by Herweg and Maly in 1992. The ignition model introduced in a KIVA-3V version already modified by the authors (re-zoning algorithm, combustion and turbulence models, cylinder wall heat transfer, etc.) has then been tested in order to assess its level of accuracy in describing this complex phenomenon, by varying the most critical engine operating conditions and keeping combustion tuning parameters unchanged. After comparing ignition model results with the corresponding ones presented by Herweg and Maly, a specific application of the overall model (KIVA-3V + ignition model + turbulent combustion model) has been made to perform an analysis of a compressed natural gas (CNG) fuelled engine for heavy-duty applications. To this aim, the in-cylinder combustion history and the related processes as the temperature distribution and NOx formation have been calculated and verified with reference to the experimental data measured in a wide range of operating conditions of an IVECO turbocharged engine.
A risk-based method for minimizing welding distortion in steel ship production
Authors: Sukovoy O , Kuo C 
Published: August 2003

The paper presents a novel approach, entitled responsibility-sharing management (RSM) which can be used to assist in effective management of welding distortion in ship production that takes into account scientific methods, procedures and management issues. The paper begins by outlining the nature of welding distortion, its impact on steel ship production and traditional methods of dealing with it before suggesting the alternative way forwards. The principles of the RSM approach are then explained and the key features of its six elements are examined. An illustrative example is used to demonstrate the effective use of this approach in a shipyard. The main conclusions are the following. Firstly, since welding distortion has a significant impact on ship production, there is, therefore, a need for a fresh systematic approach for dealing with this problem which could address not only technical aspects but also management, operation and human factors. Secondly, it is essential to encourage the development of a positive culture in the management of ship production and this is particularly relevant in efforts to minimize welding distortion.
Drug Therapy for Prevention of Recurrent Myocardial Infarction
Authors: van der Elst Menno E , Buurma Henk , Bouvy Marcel L , de Boer Anthonius 
Published: August 2003

OBJECTIVE To provide an evidence-based overview of drug treatment for long-term secondary prevention of myocardial infarction (MI). DATA SOURCES We conducted searches of MEDLINE (1966–August 2002), the Cochrane Controlled Trial Register, and the reference list of each identified study. STUDY SELECTION/DATA EXTRACTION Trials and meta-analyses were included using the following criteria: (1) randomized trials, (2) description of identification procedure, inclusion criteria, outcome measures, and statistical methods, (3) confirmed MIs, (4) treatment continued for at least 1 month, and (5) all-cause mortality as primary outcome; other events as secondary outcomes. All authors interpreted the results from trials that met the inclusion criteria. DATA SYNTHESIS In randomized clinical trials, low-dose aspirin, high-intensity oral anticoagulants, β-blockers, angiotensin-converting enzyme (ACE) inhibitors, and statins decreased the risk of mortality and reinfarction after MI. Randomized clinical trials using calcium-channel blockers, antiarrhythmics, and hormone replacement therapy did not show benefits in patients with prior MI. Effects of the combined use of aspirin or oral anticoagulants with β-blockers or ACE inhibitors plus statins must be derived from subgroup analysis of trials, but seem to be beneficial. CONCLUSIONS The use of at least aspirin or an oral anticoagulant, a β-blocker or an ACE inhibitor, plus a statin should be incorporated in the treatment routine. Clopidogrel treatment might be an alternative to aspirin. Standard addition of a β-blocker to ACE inhibitor–treated patients without reduced left-ventricular ejection fraction seems to be untimely.
Enfuvirtide: A Novel Agent for the Treatment of HIV-1 Infection
Authors: Duffalo Melody L , James Christopher W 
Published: August 2003

Objective To review the pharmacology, virology, pharmacokinetics, efficacy, safety, and clinical use of enfuvirtide. Data Sources English-language MEDLINE and AIDSline searches were performed (1966–January 2003) using enfuvirtide, T-20, gp41, and fusion inhibitors as key words. Abstracts from infectious diseases and HIV scientific meetings were identified. Data Extraction All publications and meeting abstracts were reviewed and relevant items included. In vitro and preclinical studies were included, as well as Phase II and III clinical trials. Data Synthesis Enfuvirtide is a fusion inhibitor used for the treatment of HIV-1 infection. Given its unique mechanism of action, most HIV-1 isolates are susceptible to enfuvirtide. Enfuvirtide is administered by subcutaneous injection twice daily. In clinical trials with antiretroviral-experienced patients, enfuvirtide was effective at suppressing HIV-RNA and increasing CD4+ T-cell counts. Enfuvirtide should be used in combination with other active antiretroviral agents to optimize its efficacy and limit resistance. Injection site reactions associated with administration of the drug are experienced in the majority of patients. Availability of enfuvirtide may be limited by a complex manufacturing procedure. Conclusions Enfuvirtide is an effective treatment option for HIV-1–infected individuals when used in combination with other antiretroviral agents. It may be used as part of a regimen for treatment-experienced patients.
Building Quantum Dots into Solids with Well‐Defined Shapes
Authors: Mao C. , Qi J. , Belcher A.M. 
Published: August 2003

AbstractQuantum dots (QDs) chemically synthesized in solution at a higher temperature (85 °C) were built in situ into a variety of three‐dimensional (3D) close‐packed QD ensembles (QD solids) with well‐defined shapes: needles, disks, rods, spheres, bundles, stars, ribbons, and transition structures (TSs). Design strategies using a novel cold‐treatment (–25 to 0 °C) process immediately following the synthesis of the QDs provided control over these shapes, independently from the II–VI materials used. Transformation occurred between different shapes by the rearrangement of the QDs within the QD ensembles. The QD solids were characterized by advanced electron microscopy and photoluminescence spectroscopy. The cold treatment strategy is versatile and has been applied to several II–VI QDs (CdS, ZnS, and CdSe) and may be extended to other QD systems and other chemical approaches.
Improved Efficiency of Single‐Layer Polymer Light‐Emitting Devices with Poly(vinylcarbazole) Doubly Doped with Phosphorescent and Fluorescent Dyes as the Emitting Layer
Authors: Kan S. , Liu X. , Shen F. , Zhang J. , Ma Y. , Zhang G. , Wang Y. , Shen J. 
Published: August 2003

AbstractWe demonstrate novel organic light‐emitting diode (LED) materials that contain a green phosphorescent dye (dmbpy)Re(CO)3Cl (dmbpy = 4,4′‐dimethyl‐2,2′‐bipyridine), and a red fluorescent dye 4‐dicyanomethylene‐6‐(p‐dimethylaminostyryl)‐2‐methyl‐4H‐pyran (DCM) as dopants and polyvinylcarbazole (PVK) as the host. The photoluminescence (PL) and electroluminescence (EL) properties of these complex materials were studied. The energy transfer efficiency from PVK host to DCM is increased by the (dmbpy)Re(CO)3Cl co‐dopant, which has an emission energy between that of PVK and DCM. The (dmbpy)Re(CO)3Cl, which emits a long‐lived phosphorescence, is used as an energy coupler, providing the possibility to harvest both singlet and triplet energy in the devices. The pure red emission from DCM was observed from PL and EL spectra of (dmbpy)Re(CO)3‐Cl(> 2.0 wt.‐%):DCM(> 0.5 wt. %) doped PVK films, demonstrating an efficient energy transfer from PVK and (dmbpy)Re(CO)3‐Cl to DCM. By optimizing the concentration of DCM and (dmbpy)Re(CO)3Cl in PVK, a maximum EL quantum efficiency of 0.42 cd A–1 at a current density of 9.5 mA cm–2 was obtained. The EL quantum efficiency of the doubly doped device is significantly enhanced in comparison with both a DCM‐only doped PVK device and a DCM‐doped PVK device with the green fluorescent dye Alq3 as co‐dopant. The improvement in the operating characteristics of the phosphorescent and fluorescent dye doubly doped device is attributed to efficient energy transfer in the system, in which both triplet and singlet excitons are used for resultant emission in the polymer device.
New Conjugated Ladder Polymer Containing Carbazole Moieties
Authors: Patil S.A. , Scherf U. , Kadashchuk A. 
Published: August 2003

AbstractA new ladder polymer incorporating a polar carbazole group within the main chain, ladder‐type poly(para‐phenylene carbazole), LPPPC, was synthesized and characterized by luminescence techniques. Its properties are compared to that of the well‐known methyl‐substituted ladder‐type poly(para‐phenylene), MeLPPP. The results obtained evidence a very low energetic disorder in this new polymer, presumably due to its near‐perfect intrachain structure and low content of defects. It was found that although the density of states (DOS) distribution for neutral excitations is narrower than in MeLPPP, the manifold of charge‐transporting localized states is substantially more energetically disordered due to important dipolar disorder contributions.
Star‐Shaped Oligothiophenes for Solution‐Processible Organic Field‐Effect Transistors
Authors: Ponomarenko S.A. , Kirchmeyer S. , Elschner A. , Huisman B.‐H. , Karbach A. , Drechsler D. 
Published: August 2003

AbstractWe have designed and successfully synthesized star‐shaped oligothiophenes, which could be used as semiconducting materials for solution‐processible organic field‐effect transistors (FETs). By systematically changing the chemical structure of the star‐shaped oligothiophenes we obtained the structural requirements needed for making working FETs from them. UV‐vis fluorescence measurements showed that a molecule of the star‐shaped compounds under consideration is not a fully conjugated molecule, but it has three independently conjugated oligothienyl‐phenylene blocks. A possible scheme of molecular packing of the star‐shaped oligothiophenes in a lamellar structure was proposed and confirmed by atomic force microscopy (AFM) and X‐ray diffraction (XRD) measurements. Although the star‐shaped semiconductors show a somewhat lower mobility than their linear analogs, they possess better solubility and film‐forming properties, leading to improved spin‐coating processing. The best FETs were made by spin‐coating 1,3,5‐tris(5″‐decyl‐2,2′:5′,2″‐terthien‐5‐yl)benzene from a chloroform solution, which resulted in a mobility of 2 × 10–4 cm2 V –1s–1, a 102 on/off ratio at gate voltages of 0 V and –20 V, and a threshold voltage close to 0 V.
Formation of Thick Porous Anodic Alumina Films and Nanowire Arrays on Silicon Wafers and Glass
Authors: Rabin O. , Herz P.R. , Lin Y.‐M. , Akinwande A.I. , Cronin S.B. , Dresselhaus M.S. 
Published: August 2003

AbstractA method for the fabrication of thick films of porous anodic alumina on rigid substrates is described. The anodic alumina film was generated by the anodization of an aluminum film evaporated on the substrate. The morphology of the barrier layer between the porous film and the substrate was different from that of anodic films grown on aluminum substrates. The removal of the barrier layer and the electrochemical growth of nanowires within the ordered pores were accomplished without the need to remove the anodic film from the substrate. We fabricated porous anodic alumina samples over large areas (up to 70 cm2), and deposited in them nanowire arrays of various materials. Long nanowires were obtained with lengths of at least 9 μm and aspect ratios as high as 300. Due to their mechanical robustness and the built‐in contact between the conducting substrate and the nanowires, the structures were useful for electrical transport measurements on the arrays. The method was also demonstrated on patterned and non‐planar substrates, further expanding the range of applications of these porous alumina and nanowire assemblies.
Vesicles and Liposomes: A Self‐Assembly Principle Beyond Lipids
Authors: Antonietti M. , Förster S. 
Published: August 2003

AbstractThis Progress Report describes the latest advances in vesicles and liposomes. Recent work on the self‐assembly of complex polymer systems shows that the formation of polymer vesicles or closed hull structures is archetypal, leading to fascinating new possibilities and applications in materials science. A general view of the underlying self‐assembly mechanisms leading to vesicles and the control of size, shape, and other vesicular properties by physicochemical means is presented, as background. This is followed by an overview of the recently described new classes of polymer and supramolecular tectons that make vesicle formation a more general phenomenon going beyond just lipids. Finally, the potential applications of vesicles, including non‐lipid vesicles, are outlined.
Why a universal population‐level approach to the prevention of child abuse is essential
Authors: Sanders Matthew R. , Cann Warren , Markie‐Dadds Carol 
Published: August 2003

AbstractThis paper argues for the importance of adopting a population‐level approach to promote more effective parenting and to reduce the risk of child maltreatment. Family‐based interventions based on social learning principles have been shown to make a useful contribution in the treatment of child maltreatment. However, typically such programmes have been used to treat parents who have already become involved in the child protection system. We argue that the creation of community‐wide support structures to support positive parenting is needed to reduce the prevalence of child maltreatment. Such an approach requires several criteria to be met. These include having knowledge about the prevalence rates for the targeted child outcomes sought, knowledge about the prevalence of various parenting and family risk factors, evidence that changing family risk factors reduces the prevalence of targeted problems, having culturally appropriate, cost‐effective, evidence‐based interventions available and making these widely accessible. Copyright © 2003 John Wiley & Sons, Ltd.
Formation of a new F.C.C. τ2 phase in rapidly quenched Al55Cu35V10 alloy
Authors: Misra D. K. , Tiwari R. S. , Srivastava O. N. 
Published: August 2003

AbstractX‐ray diffraction and transmission electron microscopy experiments were carried out to study the structure of rapidly solidified as‐cast and annealed Al55Cu35V10 alloy. The as‐cast Al55Cu35V10 alloy shows the presence of a new f.c.c. τ2 phase (a=0.58nm) along with a b.c.c. (a = 0.89 nm) phase which after subsequent annealing transforms into single f.c.c. phase (a = 0.58 nm). In this paper, it is also reported that these phases are crystalline approximants to an icosahedral phase on the basis of e/a (valence electron per atom) constant line. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies on optical properties of polycrystalline SnO2:Sb thin films prepared using SnCl2 precursor
Authors: Elangovan E. , Ramamurthi K. 
Published: August 2003

AbstractOptical properties of spray deposited antimony (Sb) doped tin oxide (SnO2) thin films, prepared from SnCl2 precursor, have been studied as a function of antimony doping concentration. The doping concentration was varied from 0‐4 wt.% of Sb. All the films were deposited on microscope glass slides at the optimized substrate temperature of 400 °C. The films are polycrystalline in nature with tetragonal crystal structure. The doped films are degenerate and n‐type conducting. The sheet resistance of tin oxide films was found to decrease from 38.22 Ω/□ for undoped films to 2.17 Ω/□ for antimony doped films. The lowest sheet resistance was achieved for 2 wt.% of Sb doping. To the best of our knowledge, this sheet resistance value is the lowest reported so far, for Sb doped films prepared from SnCl2 precursor. The transmittance and reflectance spectra for the as‐deposited films were recorded in the wavelength range of 300 to 2500 nm. The transmittance of the films was observed to increase from 42 % to 55 % (at 800 nm) on initial addition of Sb and then it is decreased for higher level of antimony doping. This paper investigates the variation of optical and electrical properties of the as‐deposited films with Sb doping. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical absorption spectra and related parameters of ammonium zinc chloride crystal in the antiferroelectric and commensurate phases
Authors: Gaffar M. A. , Abu El‐Fadl A. , Bin Anooz S. 
Published: August 2003

AbstractOptical absorption along the three crystallographic axes of (NH4)2ZnCl4 single crystals is reported over a temperature range from 276 K to 350 K. Our results clearly confirm the antiferroelectric to commensurate phase transition at 319 K. Analysis reveals that at the absorption edge the type of transition is the indirect allowed one. The indirect band gaps at various temperatures are determined and their temperature dependence is estimated in the antiferroelectric and commensurate phases. Optical parameters related to the temperature dependence of the energy gap are evaluated. The single‐effective oscillator model was used to describe the imaginary part of the dielectric constant, which facilitate calculation of the dipole moment parameters. The steepness parameter is given, its value is used to estimate the temperature dependence of the indirect energy gap and the result is compared with that calculated graphically. In the region of the absorption edge, the absorption coefficient obeys Urbach's rule. Urbach characteristic parameters are determined and their temperature dependence is investigated. Correlation between different parameters is considered. Most of the results confirm the optical isotropic nature of AZC crystals. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FTIR spectroscopic, thermal and growth morphological studies of calcium hydrogen phosphate dihydrate crystals
Authors: Joshi Vimal S. , Joshi Mihir J. 
Published: August 2003

AbstractCalcium hydrogen phosphate dihydrate (CHPD or DCPD) is found quite frequently in urinary calculi (stones). The CHPD crystals were grown by the single diffusion gel growth technique in sodium metasilicate gel. The crystals were found to be having platelet and broad needle type morphologies. The crystals were analyzed by FTIR spectroscopy. The thermal properties were studied by employing the thermogravimetric analysis. Various kinetic and thermodynamic parameters for dehydration were estimated. The selected platelet was studied by SEM for the growth morphologies indicating that the crystals grew in the form of leaflets having prominent (010) faces. This was in agreement with earlier reported studies. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)