bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new electronic viscometer based on Rayleigh wave mechanics
Authors: Kauzlarich James J. , Ross Robert A. , Abdallah D. Sharif 
Published: July 2006

AbstractThe operation of a new viscometer is described, based on Rayleigh wave mechanics, where a thin walled tube of 5 mm diameter is immersed to a fixed depth of 60 mm in a fluid and is made to undergo axial vibrations generated by a vibrating piezoelectric plate which supports the tube. The motion of the tube is damped by the fluid, and the piezoelectric crystal feedback circuit gives a voltage inversely proportional to the square root of the viscosity × density product. The design and performance characteristics of the patented viscometer are described.The instrument is portable and gives a measurement of viscosity × density for a test time of 1 min, over a wide range of values, and can be modified to permit continuous measurements as a function of time. The results are accurate for a Newtonian fluid, while giving an apparent viscosity × density at low shear rate for non‐Newtonian fluids. A probe measures the fluid temperature during the test. Only a small amount of fluid is necessary for measurement. Rayleigh wave mechanics theory is shown to be obeyed by the instrument.The electronic circuit uses a phase‐locked loop to drive the thin walled tube at a resonance of about 1.5 kHz. The processor feedback signal is large, varying from 2 V down to ∼0.5 V DC when measuring SAE 10 to 60 engine oils. There is an onboard computer to process the data. The computer gives a prediction of viscosity at 40 °C, or can be modified to predict viscosity at any reference temperature, for a paraffinic or a naphthenic mineral oil, as well as for various synthetic oils. For a particular fluid, it is possible to build data reduction into the computer, for example, equations for density as a function of temperature can be stored in the computer to reduce the viscosity × density result to viscosity and to density.
Sync‐period frequency analysis and its application to the diagnosis of multiple element defects of rolling bearings
Authors: Wen‐Yi Wang , Harrap Michael J. 
Published: July 2006

AbstractA method for diagnosing multiple element defects in rolling bearings has been investigated. The method combines the time‐synchronous averaging and envelope spectral analysis techniques to produce spectra of synchronously averaged envelope signals with a range of synchronous frequencies. The spectra are displayed in the synchronous period versus frequency domain, to result in the sync‐period versus frequency distribution. The distribution separates the characteristic defect frequencies and their associated sidebands in the synchronous period axis. This analysis technique makes it possible to detect and diagnose multiple defects appearing in different elements of rolling bearings. Another main benefit of the method is the significant noise reduction by both the enveloping and the synchronous averaging processes. Results from both computer synthesised data and experimental simulated data are presented.
Development of a new type of corrosive wear tester
Authors: Yanliang Huang , Baorong Hou , Xiaoxia Jiang , Shizuo Li 
Published: July 2006

AbstractA new type of corrosive wear tester has been developed, on which both static and transient corrosive wear tests can be performed. By combining the tester with an electrochemical measuring system and a dynamic strain gauge, studies can be done in fields such as polarisation curve measurement under conditions of corrosive wear, surface state and wear coefficient measurement, and dynamic observations of current under static potential, as well as the study of surface film rupture and recovery. Leakage of the solution was considered throughout the design, and was addressed by avoiding passing the rotating shaft through the electrolytic cell.
Some aspects of rolling friction resistance in a complex tribological pair – the bicycle wheel bearing
Authors: Styp‐Rekowski Michat 
Published: July 2006

AbstractBicycles are an important means of transport — over 20 million are manufactured worldwide each year, and, because their source of motive energy is human, their energy conversion, as measured by their resistance to motion, is critical. The bearings used in bicycles are rolling bearings, but are normally of different materials and construction quality to the roller bearings used in other applications.The present paper is intended to provide an indication of the phenomena influencing the resistance to motion and loss of energy of these bearings, and is based on a rolling bearing test stand designed by the author. A mathematical model derived from experimental observation is presented, and the theoretical results compared with experimental results.
A scuffing load capacity test with the FZG gear test rig for gear lubricants with high EP performance
Authors: Höhn B.‐R. , Michaelis K. , Eberspächer C. , Schlenk L. 
Published: July 2006

AbstractMethods for the evaluation of the scuffing load capacity of EP lubricants of API GL‐4 and GL‐5 performance levels have been developed for the standard FZG gear test rig, which has a centre distance of a = 91.5 mm. Procedure A10/16.6R/90 is capable of discriminating between industrial gear oils and automotive gear oils up to GL‐4 performance level while procedure S‐A10/16.6R/90 can be applied to GL‐4 and GL‐5 lubricants. The test methods were verified with reference oils and commercial gear lubricants. The results of the tests can be used to give a relative ranking of reference and candidate lubricants. They can also be used as limiting values in the scuffing load capacity rating method according to DIN 3990 (ISO DIS 6336).
A new electrochemical technique to study tribocorrosion at the micrometric scale
Authors: Assi F. , Suter T. , Böhni H. 
Published: July 2006

AbstractA new method to investigate the tribocorrosion properties of metals and alloys has been developed with which the current density of a metal probe in an electrolyte under rubbing conditions can be measured. The electrochemical microcell consists of a microcapillary (inner diameter 0.84 mm); the rubbing partner is an Al2O3 tube which rotates inside the microcapillary. Rotational speed, load and applied electrical potential can be varied, so that it is possible to analyse the corrosion rate during rubbing under various controlled conditions.With conventional tribocorrosion machines (e.g., pin‐on‐disc, ball‐on‐plate rig) and also with single‐scratch test machines, the current measured also derives from surface areas which are not undergoing mechanical wear. In the present method, the activation of specific surface areas under rubbing conditions, and subsequent repassivation, can be studied separately.
A review of condition monitoring and fault diagnosis for diesel engines
Authors: Jones N. B. , Li Yu‐Hua 
Published: July 2006

AbstractTechnical advances and environmental legislation in recent years have stimulated the development of a number of techniques for condition monitoring and fault diagnosis (CMFD) in diesel engines. This paper firstly summarises common faults, fault mechanisms and their effect on diesel engine performance. Corresponding measurands are presented. Standard CMFD methods for parameters and CMFD systems for diesel engines are reviewed. Finally, some advanced CMFD techniques, including neural networks and fuzzy logic, which may be more powerful, are discussed.
Method for scuffing propagation assessment
Authors: Piekoszezuski W. , Szczerek M. , Tuszynski W. 
Published: July 2006

AbstractThis paper describes a method for the determination of scuffing propagation using a four‐ball extreme‐pressure tester. The method has been developed at the authors' laboratory and is a completely new approach to the investigation of scuffing phenomena. A series of lubricants was prepared by blending antiwear (AW) and extreme‐pressure (EP) additives with a mineral base oil. Tribological experiments were then performed using the new method. The aim was to investigate the influence of such additives on scuffing propagation. It is shown that there is a significant influence of AW and EP additives on scuffing. Surface analyses (SEM, EDS) show the decisive role of the chemical reactions of AW and EP additives with the steel surface and their creation of a surface layer whose good antiseizure properties mitigate scuffing propagation and reduce wear intensity. It must be emphasised that the authors consider scuffing to be a process leading to the cessation of the relative movement of a tribosystem, known as seizure.
Phenomenological investigation of cutting oils: Antifriction and antiwear behaviour at low contact temperatures
Authors: Pandazaras C. N. , Ivkovic B. , Petropoulos G. P. 
Published: July 2006

AbstractThe basic reason for the use of cutting fluids in machining processes is to increase cutting tool life and to decrease machining costs. An experimental simulation of tribological processes representing rear cutting tool contact was carried out in a ‘block‐on‐disc’ (BOD) tribotester. The coefficient of friction and block wear were measured under boundary (discontinuous fluid film) and elastohydrodynamic (quasi‐continuous fluid film) lubrication conditions for neat and semi‐synthetic cutting oils. Interesting data were obtained concerning a further cutting fluid classification, which is helpful for optimal cutting fluid selection via their antiwear and antifriction characteristics.
Effect of temperature on the scuffing load capacity of EP gear lubricants
Authors: Hölm B.‐R. , Miclwelis K. , Collenberg H. , Schlenk L. 
Published: July 2006

AbstractScuffing of gears involves the welding together of locally unprotected metal‐to‐metal contacts when critical limits of pressure and temperature are exceeded. Protection can be maintained by a thick lubricant film, by physically adsorbed layers, or by chemical reaction layers. At higher temperatures, viscosity and film thickness decrease but, using an EP gear oil, due to higher chemical reactivity, the scuffing load capacity is not necessarily reduced accordingly. The reaction temperature of the additives is not always reached for large gears. In this paper the factors that influence the scuffing load capacity are investigated, and test possibilities and calculation methods are outlined.
Statistical study of organomolybdenum compounds in an engine oil formulation and the results of engine testing
Authors: Saini M. S. , Lockwood F. E. , Smith T. R. , Pridemore D. , Grulke E. A. 
Published: July 2006

AbstractOrganomolybdenum compounds are versatile lubricant additives of interest in the design of engine oils to meet the new ILSAC (International Lubricant Standardization and Approval Committee) GF‐3 performance standard, especially for fuel efficiency. In this work, organomolybdenum and 13 other components were studied by experimental design and statistical analysis to determine their effects on friction, wear, and oxidation properties. The resulting linear model was used to construct a trial engine oil formulation. Engine test results, including some new tests required for ILSAC GF‐3, confirmed some of the strengths of organomolybdenum compounds, as well as their sensitivity to other additives in the formulation.
The results of ferrography tests and their evaluation
Authors: Stodola Jiří 
Published: July 2006

AbstractThis paper discusses ways of applying mathematical methods to evaluate the results of tribodiagnostics (ferrography) related to vehicle engines. The idea is based on a discriminative analysis which makes it possible to describe one qualitative parameter, e.g., the complex technical state of the engine, by means of several quantitative parameters, e.g., the quantity of diagnosed wear particles in used oil. The results have been verified using statistical data from truck and automobile engines.
Preparation and evaluation of vegetable oil derived biodiesel esters as lubricity additives
Authors: Lang X. , Dalai A. K. , Reaney M. J. , Hertz P. B. 
Published: July 2006

AbstractVarious vegetable‐oil derived esters using methyl, ethyl, butyl, and 2‐propyl alcohols were prepared and tested as diesel fuel lubricity additives in a roller‐on‐cylinder lubricity evaluator. At1% additive treat rate, the canola methyl and 2‐propyl esters, the best‐performing esters, increased the lubricity number of a reference fuel by 60%. Statistical analyses indicated strong effects of fatty acids and alcohols on the wear, friction, and lubricity number of the fuel. While no single fatty acid was identifiably responsible for the wear reduction, certain non‐linoleic compounds correlated with the wear data in a semi‐log relationship. The low‐temperature behaviour of the biodiesel was studied using differential scanning calorimetry. The major transitional peak temperature of the biodiesel esters changed with the melting points of their primary fatty acids, and decreased with the lengthening and branching of the tail alkyl groups.
A method for testing lubricants under conditions of scuffing. Part I. Presentation of the method
Authors: Szczerek M. , Tuszynski W. 
Published: July 2006

AbstractA method for the tribological assessment of lubricants under conditions of scuffing is presented. The method uses a four‐ball tester, and allows one to assess the effect of lubricant on scuffing intensity through an analysis of changes in the friction torque and wear of the stationary balls, at continuously increasing load. The behaviour of a lubricant under scuffing conditions can be characterised using the so‐called limiting pressure of seizure poz, which depends on the load at which the balls seize and the average value of the wear area calculated from the wear‐scar diameters measured on the stationary balls.A comparison is made ‐ from the point of view of the resolution, time consumption, and cost ‐ of the new method with the existing, standard tests, using a four‐ball tester and a gear test rig (FZG). It is concluded that the proposed method, unlike standard FZG and certain four‐ball tests, enables one to differentiate between gear oils, in agreement with their API GL performance level. The very short run‐time of the new method enables one to perform more tests and obtain a low standard deviation. The new method is much cheaper than the standard four‐ball and FZG methods.
Investigation of hard lubricant coatings in space in orbit around the moon
Authors: Yarosh V. M. , Moisheev A. A. , Bronovets M. A. 
Published: July 2006

AbstractThis paper reports on friction tests of a hard lubricant coating conducted in orbit around the Moon. The measurements included those taken in terrestrial conditions in a vacuum chamber, at the launch site, and in lunar orbit. The paper includes a description of an autonomous friction simulator that was mounted outside the spacecraft. In this device, two types of friction, ‘shaft‐bush’ and ‘disc‐indenter’, have been tested. For the first time, a long experiment exploring the tribological characteristics of an antifriction coating in a real space environment in a lunar satellite orbit has been carried out. Over a fifteen‐month period, the friction units were run in the space environment. These tests indicated a tendency for the friction coefficient to reduce to a limit value in such an orbit and environment.
Laboratory evaluation of anti‐fretting lubricants
Authors: Hargreaves Doug , Singerling B. F. , Pai R. 
Published: July 2006

AbstractTo characterise the friction and wear behaviour of materials and lubricants under a variety of operating conditions, laboratory models are frequently used to provide useful information. For example, during the development and/or selection of tribomaterials and lubricants, laboratory ranking of candidate products can save many hours of field testing. A reciprocating ball‐on‐flat wear test rig has been developed to rank the performance of materials, surface coatings, and lubricants under boundary, extreme‐pressure, or fretting conditions in a variety of environments and at various temperatures. The rig design is based on ASTM G133–1995. The friction force and wear are measured on both specimens while the load, stroke length and frequency, test temperature, lubricant type, test duration, surface topography of both ball and flat specimens, specimen materials, and environmental conditions are noted.The results presented in this paper refer specifically to a series of tests performed to evaluate various anti‐fretting lubricants. Two lubricants are compared in terms of friction coefficient and wear volume over time. A clear difference is shown between the two products.
Calculation of sliding power loss in spur gear contacts
Authors: Lehtovaara Arto 
Published: July 2006

AbstractAn engineering‐level calculation model for sliding power loss in spur gear contacts is presented. Teeth contact through the line of action is modelled as a constantly changing roller contact whose radius, speed, and load can be calculated from the gear geometry under the given operating conditions. The gear mesh cycle is approximated by a large number of elastohydrodynamic contacts. A constant film thickness and a Hertzian pressure distribution are assumed in each contact. The model includes non‐Newtonian lubricant behaviour together with temperature and mixed lubrication effects in contact. The numerical solver is reasonably fast in evaluating effectively the sliding power loss dependence on the essential gear and lubricant parameters. The features and behaviour trends of the calculated sliding power losses have a close similarity with published results obtained from measurements and experiment‐based power loss models with mineral oil. The limiting shear stress of the lubricant is observed to have an essential role in the power loss behaviour especially at high loads.
Experimental evaluation of the stress distribution on the outer surface of the outer race of conventional and double‐decker high‐precision bearings
Authors: Prashad Har 
Published: July 2006

AbstractExperimental investigations have been carried out on the stress distribution on the outer surface of the outer race of conventional and double‐decker high‐precision bearings (DDHPBs). The investigations, in general, indicate that the overall level of stress variation on conventional bearings in various modes of loading under static conditions is greater than that of DDHPBs having an identical inner bore. The cyclic stress levels have been found to be higher for the outer race of conventional bearings compared to that of DDHPBs. Also, the frequency of stress cycles on the outer race of conventional bearings is greater than that of DDHPBs.A comparison of the stress distribution pattern indicates that, under identical loads, the ratio of deflection to indentation on the elements of DDHPBs and conventional bearings is less than unity. Also, under identical operating conditions, the ratio of stresses due to centrifugal forces on the elements of DDHPBs and conventional bearings of the same bore and outer diameter is less than unity. It is concluded that the life of DDHPBs as compared to conventional bearings should be longer under identical operating conditions.
Scheduling with base station diversity and fairness analysis for the downlink of CDMA cellular networks
Authors: Dianati Mehrdad , Shen Xuemin (Sherman) , Naik Kshirasagar 
Published: July 2006

AbstractEfficient packet scheduling in CDMA cellular networks is a challenging problem due to the time variant and stochastic nature of the channel fading process. Selection diversity is one of the most effective techniques utilizing random and independent variations of diverse channels to improve the performance of communication over fading channels. In this paper, we propose two packet scheduling schemes exploiting base station selection diversity in the downlink of CDMA cellular networks. The proposed schemes rely on the limited instantaneous channel state information (CSI) to select the best user from the best serving base station at each time slot. This technique increases the system throughput by increasing multiuser diversity gain and reducing the effective interference among adjacent base stations. Results of Monte Carlo simulations are given to demonstrate the improvement of system throughput using the proposed scheduling schemes. In addition, we investigate fairness issue of wireless scheduling schemes. Due to different characteristics of wireless scheduling schemes, the existing fairness indexes may result in misleading comparison among different schemes. We propose a new fairness index to compare the overall satisfaction of the network users for different scheduling schemes. Copyright © 2006 John Wiley & Sons, Ltd.
First experiences with free‐ranging giant day geckos (Phelsuma madagascariensis grandis, Gray 1870) in the masoala rainforest exhibit in Zurich Zoo, Switzerland
Authors: Furrer Samuel C. , Jaag Kathrin , von Stockar Sabine , Rübel Alex 
Published: July 2006

AbstractSixty giant day geckos (Phelsuma madagascariensis grandis) have been introduced into the Masoala rainforest exhibit of Zurich Zoo. Eighteen geckos were monitored during a 3‐month study using the telemetry method. In general, the geckos were able to adapt well under these semi‐natural conditions of the exhibit. The geckos accessed to nearly all locations in the exhibit; some of the animals remained stationary, whereas others covered dozens of meters within a week. They preferred four species of plants as well as the artificial structures supporting the walls and roof of the exhibit, and displayed natural behaviors. Animals were observed feeding on all kind of arthropods and nectar substances, and also on food items dropped from feeding stations for other species. Deliberate feeding targeted at the geckos was finally reduced to a calcium‐rich squash along the visitor's main path. Reproduction was observed frequently within the exhibit. These findings suggest that the geckos will be able to build up a self‐sustaining population and contribute to a nearly‐authentic experience for zoo visitors. Zoo Biol 0:1–7, 2006. © 2006 Wiley‐Liss, Inc.