bluuebunny/crossref_metadata_2025_split huggingface dataset:
The BM5Se9 phases: studies of the behaviour of superconductors and ferromagnets
Authors: Leblanc‐Soreau A. , Molinié P. , Jumas J.C. 
Published: July 2006

AbstractSyntheses performed in the A3B/MSe2 systems lead to the formation of (B/B′)(M/A)5Se9 phases (ferromagnets or superconductors) {A = M = (Nb, V, Ta); B = B′ = (Al, Ge, Ga, Sn, Sb)}. The magnetic studies on GaV5Se9, GaV0.15Ta4.85Se9 and Sn0.94Ga0.05V0.30Nb4.70Se9, compared to that of SnNb5Se9, GaNb5Se9 show that the presence of V modifies the superconducting exchanges and allows ferromagnetic couplings. Through Point‐Contact Spectroscopy on SnNb5Se9, it is shown that nanoclusters of the pristine NbSe2 and Nb3Sn exist, so the properties result from a synergy between them and the matrix, and it could be a mesoscopic superconductor. The superconductors's Tc values vary from 17.5(2) K for SnNb5Se9 to 6.0(2) K for SbNb5Se9, and the ferromagnetic state transition from 22K for GaV5Se9, to 35 K for Sn0.94Ga0.05V0.30Nb4.70Se9. The 119Sn and 121Sb Mössbauer studies of Sn0.94Ga0.05V0.30Nb4.70Se9 and SbNb5Se9 are compared to that obtained for SnNb5Se9 itself; for this last one, 3 types of sites corresponding to 2 species of Sn were observed with a reversible dynamic process between the 2 SnII Sn‐Se sites correlated to a modification of the Sn‐Nb site(1). SbNb5Se9, at 5 K, shows just a singlet, attributed to Sb surrounded by Se; from 298 K to 5 K, Sn0.94Ga0.05V0.30Nb4.70Se9, presents one asymmetrical Sn‐Se site without any transferred field on Sn and an increased asymmetry when T decreases. Sn0.94Ga0.05V0.30Nb4.70Se9 is a weak and complicated ferromagnet. In both cases, GaV5Se9, and Sn0.94Ga0.05V0.30Nb4.70Se9, the ESR spectrum observed at 300 K can be fitted with 2 lorentzian distributions: for the first case, with axial symmetries, for the second only one remains with an axial symmetry, belonging to the V sites. its vanadium sites are thus less symmetrical than in the first case. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The dependence of the properties of YBa2Cu3O7–δ on the starting Ba compounds
Authors: Farbod M. , Zargar Shoushtari M. , Gohari Bajestani N. 
Published: July 2006

AbstractY123 samples were prepared by a solid state method using BaCO3, BaO2 and Ba(NO3)2 as Ba source under same sintering conditions. The X‐ray patterns, Tc, Jc(77 K), stiffness, room temperature thermopower and lattice parameters were measured for as sintered, underdoped and well oxygenated samples. The results show these parameters are not the same for samples prepared using different Ba sources at different regime, reflecting the effect of Ba source on microstructure of Y123 compound. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum defect as a powerful tool for studying Rydberg transition energies with density functional theory
Authors: Van Faassen M. 
Published: July 2006

AbstractQuantum defect analysis is applied to time‐dependent density functional theory (TDDFT) calculations of the Rydberg series of the He and Be atoms. The focus of the present study is on excitation energies obtained with different exchange‐correlation potentials and kernels. Excitation energies are reobtained from the quantum defect values, and it is shown that these energies can be very accurately obtained from knowledge of the quantum defect alone. TDDFT results are compared within the adiabatic local density approximation for the case in which all virtual states are included in the calculation with results obtained when the number of states is truncated. Quantum defect analysis is used to demonstrate that truncation leads to serious errors. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
DFT study of the electronic properties of DNA–DNA and PNA–DNA double strands
Authors: Natsume Takayuki , Ishikawa Yasuyuki , Dedachi Kenichi , Tsukamoto Takayuki , Kurita Noriyuki 
Published: July 2006

AbstractThe electronic properties of DNA–DNA and PNA–DNA double strands having 3–6 base pairs (bp) were investigated by density functional theory (DFT) calculations. The binding energies and the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gaps for the PNA–DNA hybrids in the vapor phase are found to be greater than those for the DNA–DNA hybrids, regardless of the number of base pairs involved. The study supports the experimental finding that PNA displays high affinity toward a complementary DNA and that PNA–DNA strands are much more thermodynamically stable than their DNA–DNA counterparts. The results suggest much higher sensitivity in DNA sequencing with the arrays of PNA than with those of DNA. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Thermomechanical wear modelling
Authors: Cowan Richard S. , Winer Ward O. 
Published: July 2006

AbstractIt is assumed that the contact between bodies in sliding motion produces a stress field and frictional heat source that may induce severe wear from material yielding or fracture. For this situation, a thermomechanical wear model is used to develop a wear transition equation for identifying the dominant factors that will reduce or control such wear, by employing thermoelasticity analyses and contact mechanics. This equation is used to construct wear maps for ease of analysis. Studies are used to substantiate the thermomechanical wear model with experimental results that emphasise the transition from mild to severe wear for dry and lubricated metallic and ceramic sliding contacts under load.
Measurement of friction during the metalforming process
Authors: Wang S. L. , Ramaekers J. A. H. , Smeets M. J. H. 
Published: July 2006

AbstractWith the development of numerical simulation of forming processes, there is an increasing need to develop a more suitable friction description for use in the numerical simulation codes. In this paper, a plane‐strain compression tribometer is described which can measure vertical force, friction force, and vertical displacement simultaneously and accurately. Three different friction models are evaluated with the experimental results. A modified friction model is proposed and some directions are given for future research on friction in metalforming processes.
Development of the PSA TU‐3 test for valve train scuffing wear
Authors: Bovington C. , Arnould H. , Mace J.‐Y. , Brégent R. , Durrant R. 
Published: July 2006

AbstractThe development of the valve train scuffing wear test by the CEC PL‐35 group is described. This test is run on the PSA TU‐3 engine, comprises a cold/low speed and a hot/high speed phase and is of 100 h duration. Oil performance is evaluated in terms of camshaft wear and follower contact pad scuffing merit rating.Studies undertaken by the group to identify those factors essential to the control of test development are described. The evolution of the test, with the introduction of a single point fuel‐injected engine, is detailed and the consequences of this on severity and repeatability and reproducibility are discussed.
Simulation of the tribological behaviour of components and cutting tools by means of model wear testing
Authors: zu Köcker G. Meier , Habig K.‐H. , Woydt M. 
Published: July 2006

AbstractModelling the wear test process can initiate real‐life friction and wear of components and cutting tools. In this paper we describe model wear tests that were developed to discover (a) whether or not simulation of the wear processes that occur during cutting is possible, and (b) how the wear of indexable inserts can be reduced by using thin hard coatings, e.g. TiN, (Ti,Al)N, Ti(C,N) when milling metallic materials. The real‐life wear of the track groups of various tracked vehicles was also investigated, in order to evaluate the wear resistance of certain materials.
A simplified wet friction clutch test apparatus
Authors: Scott W. , Suntiwattana P. 
Published: July 2006

AbstractA small, economic, test rig to evaluate friction materials and fluids for wet clutch applications has been designed, built and commissioned. In this paper, the construction, operation and performance of the machine are described, and results are presented, for two sets of typical tests. The system is capable of recording data, and torque test track, coefficients of friction, and oil temperature rise, are given.
Model and computer simulation of friction
Authors: Rakowski W. A. 
Published: July 2006

AbstractA model, consisting of the stochastic formulae which describe the relationship between the friction coefficient and the parameters known to be significant in dry friction, is proposed for dry sliding friction between two randomly rough surfaces. The model considers the frictional phenomena which dominate in energy dissipation and which may occur simultaneously between contacting elements. The kind of interaction in a given spot of asperity contact depends on the local energy flux density. The effect of several parameters on the friction coefficient, the real area of contact, and the number of contact spots can be calculated with the FRI‐SIM program. A comparison of the simulation and experimental data shows a convergence of results.
Characterisation of soot‐laden oils by quantitative voluminosity measurements
Authors: Ryason P. R. , Hansen T. P. 
Published: July 2006

AbstractSoot‐related viscosity increase has long been recognised as a potential problem in diesel engine operation. Proposed emissions regulations have led to investigations of changes in combustion to reduce soot emissions. Some of these changes, though effective in reducing exhaust soot emissions, result in increased amounts of soot in the crankcase. With a potential for a renewed emphasis on control of soot‐related crankcase oil viscosity increase, methods of characterising soot‐laden oils have become desirable. In this paper, a method is described to compare viscosity increases in different oils produced by soot in a given engine. Precision controlled shear rate rheometry can be used to determine the voluminosity of an engine soot in an oil. Comparison of voluminosities ranks oils quantitatively.
The effect of surface roughness on contact and stress states of spur gears
Authors: Väradi K. , Kozma M. , Poller R. 
Published: July 2006

AbstractThe contact characteristics of spur gears are analysed, taking into consideration real surface micro‐geometry, and using numerical algorithms. The contact pressure distribution, contact area, and rigid body rotation of the gears have been calculated for different types of gear surface according to machining: shaping, grinding, or milling. Finally, the sub‐surface stress state is evaluated for different pressure distributions, by finite element method.
Tribological problems of mineral comminution
Authors: Scieszka S. F. 
Published: July 2006

AbstractA laboratory method has been developed which involves the use of three new rigs simulating the grinding action in the majority of existing types of mills. All three rigs combine abrasion and erosion with comminution processes. The object of this investigation was to develop a test procedure that would be suitable for general use in estimating the abrasiveness of particular minerals, and to study abrasive wear in various grinding systems. Three separate industrial problems involving coal grinding have been investigated by means of the novel apparatus.The results from the relatively simple laboratory procedures, designed and operated according to the principles of similarity, may be used to predict the service life of grinding machine elements.The tribo‐testing procedure and apparatus can be used to evaluate the abrasiveness of any granular mineral, and for testing the wear resistance of any material in abrasive or erosive action. A second paper (see p. 257) publishes results obtained using the apparatus.
Laboratory evaluation of the dispersancy power of a gasoline engine oil and its relationship with sequence VE test results
Authors: Hipeaux J. C. , Durand J. P. , Prigent M. , Binet D. , Rossi A. , Vallez D. 
Published: July 2006

AbstractThe evaluation of the dispersancy power of a gasoline engine oil is included among such international specifications as those of the Committee of Common Market Automobile Constructors (CCMC) and the American Petroleum Institute (API). Such an evaluation is carried out by means of long, severe, and expensive engine bench tests, the engines used being Mercedes M102E (CCMC G4 and G5 levels) or the Ford Pinto 2.3 (API SG and SH levels). The cost of these tests necessitates pre‐selection of oils by laboratory tests and these need to be a reliable indicator of bench test performance. The present study proposes two new laboratory methods, the OXYDISP and the POTDISP tests, which associate artificial ageing of the lubricants with modified blotter spots tests. These tests showed excellent correlation with Sequence VE engine test results. They were also capable of distinguishing oils of different API standards. They therefore provide an effective tool for preselection of lubricants, without pretending to be a replacement of or substitute for Sequence VE or other engine bench tests.
Stress and fatigue analysis of fretting on a stressed specimen under partial slip conditions
Authors: Fouvry Siegfried , Ruiz Franscisco , Kapsa Philippe , Vincent Léo 
Published: July 2006

AbstractA new Fretting on a Stressed Specimen (FSS) device has been conceived to help evaluate the influence of static stress on cracking during fretting wear in a sphere‐on‐plane contact. The mechanical analysis of the stressing state induced by such a loading has been performed for elastic conditions. It is completed by the analytical determination of multiaxial Dang Van's fatigue crack nucleation criterion. The theoretical developments are confirmed by tests on a well‐known low alloy steel. Analysing the stressing state of the maximum loading condition at the critical surface contact borders, it is shown that a simple uniaxial approach can be used to define the crack nucleation risk in fretting wear and FSS. Comparing the classic fatigue descriptions that define the admitted alternated stress amplitude as a function of the mean stress value, the VDI approach is found to be the most relevant. Satisfying the linear relationships between stress components, specific FSS relationships are introduced to fit the experiments better. Because of this analytical description, all materials, surface, geometry, and contact parameters can be connected.
Measurement of wear in radial journal bearings
Authors: Ligterink D. J. , De Gee A. W. J. 
Published: July 2006

AbstractIn this article, the measurement of wear in radial journal bearings is discussed, where a distinction is made between stationary and non‐stationary contact conditions. Starting with Holm/Archard's wear law, equations are derived for the calculation of the specific wear rate k of the bearing material as a function of the wear depth d, measured after an experiment or a period of use in practice. It is also possible to calculate a value for the maximum allowable apparent pressure pa at given values of k, required lifetime and maximum allowable wear depth d, or a value of d at a given value of pa. In order to facilitate the use of the equations mentioned above, non‐dimensional diagrams are presented. Two examples are given to explain the use of these diagrams.
FT‐NMR and FTIR applications in lubricant distillates and base stocks characterisation
Authors: Adhvaryu Attanu , Sing I. D. 
Published: July 2006

AbstractLubricant distillates undergo different stages of refining in order to produce the quality required of base stock for lubricating oil formulations, incorporating different additives in various doses. It is essential to monitor the degree of refining at different stages and additive response in base stocks, using fast and accurate techniques. FT‐NMR and FTIR techniques offer a new dimension to the monitoring and characterisation of lubricant distillates and base stocks.In the present paper, an attempt is made to demonstrate the application of these techniques to deriving some average structural parameters and to correlate them with various physico‐chemical characteristics of lubricant distillates and base stocks. These correlations could be used to optimise various process parameters during the refining of lubricant distillates. If the process parameters are constant, such correlations could be used to predict the quality of the base stocks obtained from any change in the composition of the lubricant distillates. Various applications of FTIR in base oil characterisation and its processing are also reviewed.
Structures of adsorbed zinc dithiophosphates and their relationship to engine wear
Authors: Yamaguchi E. S. , Ryason P. R. 
Published: July 2006

AbstractZinc dithiophosphates (ZnDTPs) have been used extensively as anti‐wear agents for over 30 years. The mechanism of action of these remarkable materials is not fully understood. In particular, the molecular composition of the antiwear film produced by the ZnDTPs remains an area requiring investigation.In this paper, the molecular composition of adsorbed ZnDTPs on aluminium oxide (Al2O3) surfaces has been studied using Inelastic Electron Tunnelling Spectroscopy (IETS), a highly sensitive molecular spectroscopy specifically applicable to surface species at low coverages. As such, it complements other surface science techniques for determining surface compositions. A vibrational spectroscopy, IETS utilises the literature on group characteristic frequencies available from the very extensive correlations developed for infrared and Raman spectra. Thus, functional groups may be identified that are formed by the reaction of a lubricating oil additive with a metal surface covered by a native oxide.Using IETS, we show that ZnDTP aryl esters are dissociatively chemisorbed, and do not appear to form P=S groups bonded to the surface. By contrast, primary and secondary ZnDTPs retain the phosphate ester groups and bond to the surface by the P=S bond to different degrees. These spectral differences are qualitatively correlated with the observed antiwear performance of these materials.
Condition monitoring of aircraft by quantitative filter debris analysis
Authors: Bennett L. G. I. , Swanson Sarah , Koza F. D. , Poland J. S. 
Published: July 2006

AbstractVarious condition monitoring techniques are used collectively to monitor the health of aircraft engines and transmission, a concept known as Integrated Health Monitoring (IHM). A well‐established quantitative technique is Aircraft Oil Analysis (AOA), in which spectroscopic techniques such as Rotating Disk Electrode Atomic Emission Spectroscopy (RDE‐AES) are employed to analyse periodic oil samples for wear debris. Usually, no sample preparation is undertaken, as the oil sample containing both dissolved and suspended metallic wear debris is analysed directly. AOA works well for oil‐lubricated systems with relatively coarse filtration that allow circulation of the debris and its subsequent abrasive contact with moving components. To avoid this secondary wear, finer filtration is employed on both new and older aircraft. Less wear debris, and thus information, is available in the oil. A technique that quantitatively analyses the wear debris caught on the filter has been developed and is termed Quantitative Filter Debris Analysis (QFDA).Actual oil filters from CF88 Challenger ALF 502L‐2C and Hornet F404 engines were obtained in sequence, when possible, prepared by the developed procedure, and analysed with AOA instrumentation. With sufficient results, both normal and abnormal levels of wear rates emerged, as has been recorded and used for AOA. Moreover, trending of the data for sequential samples has demonstrated the capability of GFDA for condition monitoring.
Estimation of lubricant interlayer shear strength under conditions of imperfect boundary lubrication
Authors: Konchits V. V. , Markova L. V. 
Published: July 2006

AbstractThis paper considers the use of contact electrical conductivity for investigations into molecular tribology. The shear strength of thin lubricant films has been studied at nominal point contact between two crossed cylindrical steel probes. The interface was simultaneously monitored using electrical contact resistance. It is shown that the binomial law of friction holds for the sliding path portions where electrical measurements point to a continuous lubricant film. The experimental data can be used to evaluate the molecular friction parameters. An algorithm and software with which to evaluate shear strength and its components under conditions of imperfect boundary lubrication have been formulated.
A new tribometer for measuring friction data at high temperature in a continuous operation
Authors: Dalverny Olivier , Denape Jean 
Published: July 2006

AbstractThis paper describes a rotary tribometer that can function at high temperature in a pin‐on‐disc or ring‐on‐disc configuration. With this tribometer the tribological properties of ceramics (structural ceramics or coatings) and metallic alloys can be studied from room temperature to 900 °C. The sliding velocity can be varied from 0.1 to 1.5 m/s, and the normal load from 10 to 2000 N. The test apparatus is unique in terms of the wide range of loads which can be tested, and in its sensor and computer data acquisition system, which allows different test parameters, such as friction coefficient, vertical displacement of samples, and temperature near the interface, to be measured in one continuous operation.
Modelling lubricated friction for dynamic contact systems
Authors: Hess Daniel P. 
Published: July 2006

AbstractMulti‐valued friction is often observed in lubricated contact systems operating under unsteady sliding conditions. In the past, this behaviour has been modelled using a measured time delay between changes in sliding velocity and resulting changes in friction. More recent work has revealed that fluctuations in normal separation are the principal cause of this deviation from steady friction behaviour. This paper demonstrates that tangential contact dynamics can result in apparent deviations from steady friction that can resemble true deviations found from fluctuations in normal separation. Two different dynamic models are considered. One model accommodates the tangential rider dynamics of a friction test apparatus. The other model considers the possibility of tangential dynamics associated with asperity contacts.
Performance of a microgrooved journal bearing under steady and dynamic loading
Authors: Hargreaves D. J. , Armatys D. 
Published: July 2006

AbstractThis paper looks at the performance of plain, longitudinally and transversely grooved journal bearings. An experimental apparatus was created to test the performance, in terms of frictional torque under static and dynamic loading, of each of the three bearing types, to try and understand whether grooving created a different film thickness. The tests were carried out for various combinations of load and speed. The results showed an agreement between theoretical and experimental values that gave some confidence in the experimental methods, and showed the frictional torques between the plain and longitudinally grooved bearings to be similar at all loads, and at lower rather than higher speeds, while those of the transversely grooved bearing differed from the others.