bluuebunny/crossref_metadata_2025 huggingface dataset:
State Aid Control: Substance and Procedure in the Europe Agreements and the Stabilisation and Association Agreements
Authors: Cremona Marise
Published: June 2003

Abstract:  Community agreements with third countries frequently contain provisions on State aids. These provisions are designed to achieve a range of different objectives, related both to developing trade between the contracting parties and to economic and legal/regulatory development within the partner State. This paper takes a particular model of State aid clause—those found in the Europe Agreements (EAs) and the Stabilisation and Association Agreements (SAAs)—in order to explore the implications of a harmonisation obligation applied within the context of accession to the EU. In these agreements the State aid rules—and in particular those relating to the application of Community‐based criteria—are intended to contribute to the pre‐accession adoption of the acquis communautaire by the associate States (including those who are not yet candidates). These clauses are striking in their emphasis on the full adoption of Community‐based standards for the approval of aids, including large quantities of ‘soft law’, while saying very little as to the appropriate procedures for enforcement. The experience of implementing these clauses illustrates the practical difficulties of applying Community norms and standards outside the procedural structures, integration mechanisms and single market objectives of actual EU membership. The associate States are required to demonstrate their capacity for applying and enforcing the Community‐derived rules while balancing the needs of their own economic development against an undefined ‘common interest’.
Administrative and Court Reform in Central and Eastern Europe
Authors: Emmert Frank
Published: June 2003

Abstract:  The pre‐accession programmes of the European Union and the candidate countries have focused heavily on law reform. Only relatively recently, it was recognised that successful administrative and court reform would be just as necessary in order to achieve the desired goals, namely that the candidates would eventually be able to take on their obligations as new members of the Union. Unfortunately, it has now become evident that it is easier to write new laws than to get them properly applied in every day practice. This article describes a number of cases to illustrate the problem. It shows that administrators and judges in Central and Eastern Europe have significant difficulties with Western working methods, specifically the application of international norms in the national legal order, due process and procedural safeguards, treatment of precedents, resolution of ambiguities and lacunae in the law, etc., which may in turn result in unjust and sometimes absurd application of laws. These difficulties cannot be resolved merely by organising ever more training courses and other theoretical programmes. The author claims that the majority of efforts promoting administrative and court reform applied so far have rendered only meager results. Therefore, additional and more creative measures have to be designed and implemented and have to be continued for years beyond accession of most of these countries to the EU in 2004. Otherwise, rule of law deserving its name will not materialise in the new Member States. The author concludes by offering some ideas based on many years of experience in the region.
On parole: prison service industrial relations
Authors: Corby Susan
Published: June 2003

The voluntary and statutory measures to prevent prison officers from taking industrial action are examined in the context of the measures adopted to prevent industrial action by other groups of public servants. The paper concludes that the government does not have an overall strategy on strikes in essential public services, though it applies the most restrictive provisions to prison officers.
Unions fit for young workers?
Authors: Waddington Jeremy , Kerr Allan
Published: June 2003

If trade unions are to reverse the membership decline sustained since 1979, more young workers must be recruited. This paper examines the views of young workers towards trade unions by reference to survey data. It argues that there is little evidence of a ‘Thatcher’s children’ effect in which principled opposition to trade unionism is widespread. Instead the paper shows that shifts in the labour market, the effects of employer resistance to trade unionism and union inefficiencies have a marked effect on the unionisation of young workers.
So what’s the news? Management strategies towards non–union employee representation at News International
Authors: Gollan Paul J.
Published: June 2003

In an environment of what would appear to be a widening ‘representation gap’ developing in many organisations, there has been considerable discussion on the effectiveness of non–union employee representation (NER) structures as communication devices and mechanisms for employee involvement, or as a substitute for unions in the collective bargaining process. The underlying debate centres on whether NER forms make trade unions unnecessary, or whether NER forms have a role different from, but complementary to, that of unions at the workplace. The findings of this study suggest that a ‘substitute’ or union avoidance strategy as used at News International Newspapers could have limitations. The implications of not recognising these limitations could result in greater indirect union influence in workplace issues and greater employee dissatisfaction at the workplace.
European dimensions to collective bargaining: new symmetries within an asymmetric process?
Authors: Marginson Paul , Sisson Keith
Published: June 2003

The impact of economic and monetary union on the structures, processes and agenda of collective bargaining at sector and company levels is explored. Drawing on cross–national evidence from two sectors, considerable differences between sectors within national boundaries are identified, but also some striking parallels within sectors across national boundaries. Convergence and greater diversity are simultaneously evident.
The impact of the national minimum wage on the apparel industry
Authors: Undy Roger , Kessler Ian , Thompson Marc
Published: June 2003

This analysis of the NMW’s initial impact in the apparel industry focuses on organisational and institutional factors in explaining the effects on pay and related issues. The NMW had a marked effect on national terms and conditions, in particular raising the minimum earnings level. At the local level, it impacted directly on the pay of a small number of employees in almost half the 42 organisations surveyed in the East Midlands and Northern Ireland. These tended to be the larger employing units facing foreign competition and selling into the domestic market. Also, in some workplaces, the NMW adversely affected the piecework system. The reaction of local management to these changes is discussed.
European economic government and the corporatist quid pro quo
Authors: Teague Paul , Donaghey James
Published: June 2003

This article examines the effect which the evolving system of European Economic government is having on national corporatist type deals. This is done by first outlining the institutional formation of European Economic government and second examining two case studies—one from Finland and one from Ireland.
The decentralisation of Japan's wage setting system in comparative perspective
Authors: Weathers Charles
Published: June 2003

Japan's wage setting system has undergone considerable decentralisation since 1995. An overview of recent changes, framed by comparative analysis, suggests that rapid change has occurred because of the informal institutionalisation of industrial relations practices, which reflects in turn the strong enterprise consciousness of workers and unions.
Barriers to the development of teamworking in UK firms
Authors: Scarbrough Harry , Kinnie Nicholas
Published: June 2003

This paper is based on an empirical study of barriers to the adoption of teamworking in seven UK firms, including small manufacturing units, pharmaceutical organisations and telephone call centres. Such barriers arise from the tension between the ‘microcultures’ of teamworking at firm level and the logistical pressures of the supply chain. Successful adoption is seen as depending on management's ability to embed teamworking practices in the development of supply chain relationships.
Post‐privatisation industrial relations in the UK rail and electricity industries
Authors: Arrowsmith James
Published: June 2003

Commercial firms in industries once under public ownership generally have well‐organised trade unions with significant disruptive capacity, yet overt confict is often low despite major change. This paper examines the experience of two major rail and energy companies after privatisation. The results demonstrate the importance of sectoral characteristics, and the form of privatisation itself, in shaping industrial relations. The exercise of strategic choice at firm level also undermines any general industrial relations ‘theory of privatisation’.
We’re on a road to somewhere: women's groups in unions
Authors: Parker Jane
Published: June 2003

Women's groups (WGs) provide a platform from which women can develop their strengths, advance their concerns and access empowering positions. Academic attention to WGs in British unions has recently increased, reflecting their expansion and growing union responsiveness to female members. However, the meaning of WGs for unions remains under‐researched. This article examines this using case studies of two major unions and a range of their WGs based on a typology of equality ideas and model of union organisation.
Welfare Effects of National Taxes in an Economy with Regions
Authors: Petchey Jeffrey D. , Levtchenkova Sofia
Published: June 2003

The present paper illustrates that changes in national commodity and income tax rates will affect the location choices of mobile factors of production within an economy with regions as well as the total supply of these factors to the economy. It is also argued that revenue (expenditure) neutral changes in the tax mix, for example, an increase in the commodity tax combined with a decrease in the income tax rate, will affect the domestic distribution of mobile factors, their supply to the economy and social welfare. In other words, revenue neutrality should not be used as a guide to the welfare effects of tax mix changes.
Who Cites What?
Authors: Clements Kenneth W. , Wang Patricia
Published: June 2003

The present paper analyses citations in the work of a large number of PhD students. We show that the pattern of citations of journal articles, books and other reference material differs substantially across areas within economics. An investigation of reciprocal citations reveals a surprisingly low degree of communication among the Group of Eight universities and a high propensity to cite authors from the same institution, especially supervisors. We also analyse the Australian share of cited works, and identify journals, articles and authors that PhD students value highly.
Enterprise Bargaining and Productivity in Australia: What do We Know?
Authors: Loundes Joanne , Tseng Yi‐Ping , Wooden Mark
Published: June 2003

There appears to be widespread consensus, at least in industry and government, that enterprise bargaining has been beneficial for productivity. Many academics, however, have argued that the link between bargaining structure and workplace productivity is a contentious one, and that research has been unable to establish a relationship. The present paper re‐examines the existing evidence. The review reinforces the need to exercise caution before asserting that enterprise bargaining is necessarily beneficial for workplace productivity. The main conclusion that emanates from this review, however, is not the absence of a clear‐cut finding, but how poorly developed the relevant research literature is.
A Test of Alternative Measures of Disconfirmation*
Authors: Spreng Richard A. , Page Thomas J.
Published: June 2003

Disconfirmation has been widely used in a number of research traditions, however there are many different operationalizations of this construct. Little research has investigated the relative effectiveness of these various methods. The research reported here examines five operationalizations of disconfirmation and their effect on satisfaction. These tests are carried out using two different comparison standards in two different settings. The results indicate some methods are better in certain situations and are inappropriate in others. Implications for both practical and theoretical research are discussed.
Project‐Level Reuse Factors: Drivers for Variation within Software Development Environments*
Authors: Rothenberger Marcus A.
Published: June 2003

Systematic reuse can dramatically improve software development productivity and quality even though a software reuse methodology may require substantial investments. Some projects may fail to achieve the targeted amounts of reuse within organizations that are overall successful in employing reuse. To explain such variation, this research explores the effects of project‐level factors in the success of software reuse. A model that relates project factors to project reuse success is developed using an information‐rich case study approach. The results are based on the insights obtained in a nominal group technique session, triangulated with structured interviews and comparative case studies. Success factors identified by the study relate to client influence, project culture, project attributes, and developer reuse experience. An organization that can successfully identify the factors affecting potential software reuse will be able to better target investments for the improvement of its reuse methodology and thus positively affect its software development productivity and quality.
Quantitative Comparison of Approximate Solution Sets for Bi‐criteria Optimization Problems*
Authors: Carlyle W. Matthew , Fowler John W. , Gel Esma S. , Kim Bosun
Published: June 2003

We present the Integrated Preference Functional (IPF) for comparing the quality of proposed sets of near‐pareto‐optimal solutions to bi‐criteria optimization problems. Evaluating the quality of such solution sets is one of the key issues in developing and comparing heuristics for multiple objective combinatorial optimization problems. The IPF is a set functional that, given a weight density function provided by a decision maker and a discrete set of solutions for a particular problem, assigns a numerical value to that solution set. This value can be used to compare the quality of different sets of solutions, and therefore provides a robust, quantitative approach for comparing different heuristic, a posteriori solution procedures for difficult multiple objective optimization problems. We provide specific examples of decision maker preference functions and illustrate the calculation of the resulting IPF for specific solution sets and a simple family of combined objectives.
A Transaction‐Efficiency Analysis of an Internet Retailing Supply Chain in the Music CD Industry*
Authors: Rabinovich Elliot , Bailey Joseph P. , Carter Craig R.
Published: June 2003

The emergence of the Internet may have fundamentally altered the mechanisms underlying information exchanges between sellers and end consumers. However, little attention has been given to the impact these mechanisms have on the efficiency of supply chain operations.

This paper begins to address this deficiency in the literature by evaluating supply chain transaction efficiency effects from Internet purchases by consumers. It develops and empirically tests a theoretical framework examining the role Internet purchases have in establishing transaction‐efficiency levels in product exchanges involving sellers, placed at different supply chain echelons, and consumers. The theoretical framework integrates the transaction‐cost and internet economics, inter‐organizational information systems, and supply chain management literatures. Empirical testing, via structural equation modeling, is based on archival data in the Internet music CD market.

The results show that Internet‐mediated purchases by consumers allow for greater transaction efficiencies when inventory ownership is postponed farther upstream in the supply chain and supply chain echelons are disintermediated. The results also indicate that channel structure configuration, defined by the supply chains' Internet retailing echelon, moderates these transaction efficiency effects.
A Resource‐Based View of Strategic IT Alignment: How Knowledge Sharing Creates Competitive Advantage
Authors: Kearns Grover S. , Lederer Albert L.
Published: June 2003

A critical decision problem for top management, and the focus of this study, is whether the CEO (chief executive officer) and CIO (chief information officer) should commit their time to formal planning with the expectation of producing an information technology (IT)‐based competitive advantage. Using the perspective of the resource‐based view, a model is presented that examines how strategic IT alignment can produce enhanced organizational strategies that yield competitive advantage. One hundred sixty‐one CIOs provided data using a postal survey. Results supported seven of the eight hypotheses. They showed that information intensity is an important antecedent to strategic IT alignment, that strategic IT alignment is best explained by multiple constructs which operationalize both process and content measures, and that alignment between the IT plan and the business plan is significantly related to the use of IT for competitive advantage. Study results raise questions about the effect of CEO participation, which appears to be the weak link in the process, and also about the perception of the CIO on the importance of CEO involvement. The paper contributes to our understanding of how knowledge sharing in the alignment process contributes to the creation of superior organizational strategies, provides a framework of the alignment‐performance relationship, and furnishes several new constructs.
The Impact of Information System Personnel Skill Discrepancies on Stakeholder Satisfaction
Authors: Tesch Debbie , Jiang James J. , Klein Gary
Published: June 2003

System development efforts depend to a large degree upon how well information systems (IS) managers, IS specialists, and IS users work together in a project team structure. Yet, these individuals frequently work under different perceptions about matters of importance to development, management, and success. This paper introduces a framework for examining IS specialists' skill requirements from a multiple‐stakeholder perspective. Derived from discrepancy theory, the framework concedes that different stakeholders hold a variable set of expectations for IS personnel skill levels as well as a perception of skills held by IS personnel. We examine differences in expectation and performance expressed by each group and describe the impact of the discrepancy on user satisfaction, career satisfaction of IS specialists, and on job performance evaluations by IS managers. Results confirm that a discrepancy between an IS specialist's expectations of skill and their perceived skill self‐proficiency impacts career satisfaction. Similar relations hold for IS managers and users. Since different stakeholders may hold different perceptions, satisfaction of all parties becomes problematic unless a common frame of reference can be determined.
A Generalized Framework for Quantity Discount Pricing Schedules
Authors: Rubin Paul A. , Benton W. C.
Published: June 2003

The use of price to influence a buyer's purchasing behavior and thus improve supply chain coordination has received considerable attention. The vendor and buyer are independent economic entities, each maximizing its own profit. We consider the case of a buyer with fixed annual demand, independent of cost. The vendor's objective is to set a price schedule that encourages the buyer to raise its order quantity, increasing the vendor's profits. We present a unified treatment of the problem, categorize different variations, and provide a common solution procedure for all cases.
Heat Separation in Frictional Rotor-Seal Contact
Authors: Larsson Bjo¨rn
Published: June 2003

The development of thermal bows in rotors is frequently reported. The cause of the bows is an asymmetric temperature distribution as a result of uneven heating. The heat source can be a friction contact between rotor and seal. Both partial and full annular rub can give asymmetric heating. A general model for these two cases is a rotor with an arbitrary elliptic orbit and an eccentric position in an elliptic seal. Depending of these kinematics, different regions of the rotor and seal are heated and the heat flow resistance effected. Closed-form solutions of the heat conduction in three spatial dimensions are well known for the point source and after integration this is suited for friction heat analysis. When the temperature distribution is expressed the thermal bow follows as a volume integral. This paper focuses on the relation between rotor vibration (via friction heating in the seals) and the thermal bow. The coupling from rotor bow back to vibrations is treated in a later work. The main contribution of this paper is a semi-analytical solution of the thermal bow dynamic function.
TEHD Lubrication of Mechanical Face Seals in Stable Tracking Mode: Part 1—Numerical Model and Experiments
Authors: Brunetie`re Noe¨l , Tournerie Bernard , Fre^ne Jean
Published: June 2003

After a short presentation of state-of-the-art experimental studies on the thermal behavior of non-contacting face seals, the literature about numerical models for thermal effects is investigated. Next, the geometry, kinematics and dynamics of a steady state three-dimensional model are developed. Simplified Navier-Stokes equations, a generalized Reynolds equation and an energy equation with proper boundary conditions are established for flow regimes, varying from laminar to turbulent. The numerical computer code for solving the governing equations is presented and representative results are shown. It is demonstrated that face distortions strongly modify the seals’ thermal behavior. An original test rig has been developed in order to ensure full fluid film conditions. This apparatus and the experimental procedure are described. The ability of the numerical model to simulate real configurations is also illustrated. Theoretical and experimental results are in good agreement. Yet an improved model of heat transfer on boundaries is still needed.
TEHD Lubrication of Mechanical Face Seals in Stable Tracking Mode: Part 2—Parametric Study
Authors: Brunetie`re Noe¨l , Tournerie Bernard , Fre^ne Jean
Published: June 2003

In this paper, the influence of the design and operating parameters on the TEHD behavior of Mechanical Face Seals (MFS), in steady dynamic tracking mode, is analyzed for two different types of applications. First, an extensive parametric analysis of a typical MFS with very low leakage is presented. Then, the influence of rotational speed, sealed fluid temperature and pressure, rings materials, shape, waviness and misalignment of the rotor, are successively examined. The use of an original dimensionless parametric analysis leads to a very simple and overall description of the results. It is shown that ignoring the thermoelastic distortions of the rings could be misleading as far as the evaluation of MFS performance is concerned. In the final part, a hydrostatic MFS with a very large gap and flow rate is studied. The increase of the rotational speed induces a progressively turbulent radial flow. In this case, it is shown that neither thermal effects nor fluid flow regime significantly affect seal behavior.
Using Ceramic Balls to Reduce Noise in a Linear Guideway Type Recirculating Linear Ball Bearing
Authors: Ohta Hiroyuki , Nakagawa Takumi
Published: June 2003

A new method of reducing the noise of the linear guideway type recirculating linear ball bearing (linear bearing) was studied. In the experiments, the overall sound pressure levels of linear bearings with steel balls or ceramic Si3N4 balls were measured, and sound frequency analyses were carried out. Moreover, based on the assumption that the main cause of the noise may be the collision between the ball and the carriage, the overall sound pressure levels of the linear bearings were analyzed combining the Hertzian theory and the results of previous studies on collision sound. From the results of experiments and analyses, the conclusions were obtained as follows: (1) The overall sound pressure level of the linear bearing with steel balls can be reduced by about 4.5 dB by using Si3N4 balls having the same diameter; (2) The overall sound pressure levels of linear bearings with steel balls or ceramic Si3N4 balls were both increased by about 9.8 dB as the linear velocity increased an octave; and (3) The analytical results, based on the assumption that the main cause of the noise emitted from the linear bearings is the collision between the ball and the carriage, match the experimental results well.
Study of Interfacial Phenomena Affecting Thermosonic Wire Bonding in Microelectronics
Authors: Jeng Yeau-Ren , Lin Jeng-Nan
Published: June 2003

Thermosonic ball bonding is the method of choice for many interconnections to integrated circuits. This study investigated the effects of bonding parameters on bonding strength using a thermosonic bonding machine and a shear tester. Theoretical analyses were conducted to relate bonding strength to interfacial contact phenomena. Our results show that bonding strength of thermosonic wire bonds can be explained based on frictional energy intensity and real contact area. When the ultrasonic power is small, the bonding strength increases with increasing real contact area mainly caused by the bonding force. Increasing the bonding force can hardly increase the frictional energy intensity, but it can increase the real contact area, thus increasing the shear force. For larger ultrasonic power, the ultrasonic power plays an important role in increasing the bonding strength at the interface between the wire and the pad. Increasing the ultrasonic power increases both the frictional energy intensity and the real contact area, thus increasing the shear force until before the frictional energy intensity reaches a critical point. Moreover, increasing the welding time increases both the frictional energy intensity and the real contact area, thus increasing the shear force before the critical frictional energy intensity is attained; this is far smaller than the critical frictional energy intensity when the ultrasonic power is varied.
Design Consideration of Contact/Near-Contact Sliders Based on a Rough Surface Contact Model
Authors: Iida Kohei , Ono Kyosuke
Published: June 2003

We numerically investigated contact characteristics of a contact pad with a rough disk surface and the possibility of contact/near-contact sliders, using a single-degree-of-freedom (1-DOF) slider and a random wavy surface model with random roughness. Contact characteristics of a contact pad are numerically calculated based on a modified Greenwood-Williamson model, considering the bulk deformation of the surface due to all other asperity contact forces. It was found that contact stiffness and other characteristics are mainly determined by asperity contact, to the extent that the contact pad penetrates into the upper standard deviation of asperity peak height. However, the contact stiffness tends to approach a constant value as the pad penetrates into the average asperity height because the bulk deformation becomes predominant. From the numerical simulations of a 1-DOF air bearing slider model in contact and near-contact regimes over a random wavy surface with random roughness, a typical example of design condition of disk surface waviness in terms of the tracking ability and wear durability are shown, and the possibility and difficulty of a contact/near-contact slider is discussed. Finally, we analyzed meniscus effects on the contact characteristics and found a hysteresis process of the touch down and take off of a slider due to the meniscus force.
Evaluation of a Model for the Evolution of Wear in a Scotch-Yoke Mechanism
Authors: Sawyer, W. Gregory , Diaz, Kelvin I. , Hamilton, and Matthew A. , Micklos Brian
Published: June 2003

A nearly ideal two-dimensional scotch yoke mechanism was constructed to test a model of wear depth as a function cycle number. Model variables include the reciprocating mass, a two dimensional wear-rate, crank radius, and angular velocity. The model originally developed by T. A. Blanchet (1997), was nondimensionalized and simplified under conditions of large numbers of cycles, to predict the importance of including coupling based solely on a ratio of maximum allowable wear depth to the crank radius. Experiments show a linear progression of wear over two distinct regions, suggesting a sudden transition in wear modes just after 1.5 million cycles. The need for cycle or time dependent wear rates in analysis, which is a potentially far more significant source of error, is clearly illustrated by the experiment and discussed.
Investigation of Top of Rail Lubrication and Laser Glazing for Improved Railroad Energy Efficiency1
Authors: Aldajah Saud , Ajayi Oyelayo O. , Fenske George R. , Kumar Sudhir
Published: June 2003

Two new technologies have recently been developed that can help to solve some of the wheel rail contact problems. The first is a method of top of rail lubrication (TOR) or friction modification (FM). The second is a technique of laser glazing of steel rails. Both technologies help in reducing the friction, wear, and energy consumption in the wheel rail contact. This paper introduces the two technologies and presents some specific aspects of both methods. A 1:12 scale wheel/rail simulator (LA 4000) was used to study the potential of these two new technologies on energy savings. In order to develop an efficient top of rail lubrication system, all parameters affecting FM consumption rates have been studied. These parameters include speed, angle of attack, load and lubricant quantity. LA 4000 friction/wear studies were conducted to evaluate the effect of laser glazing and TOR lubricant on the lateral slip forces between a simulated wheel/rail. Three conditions under dry and lubricated environments were studied: unglazed wheel and an unglazed rail, an unglazed wheel against a glazed rail, and a glazed wheel against a glazed rail. The results of the tests indicate that the use of TOR and laser glazing does indeed reduce the lateral forces, which are an indirect measure of the damage caused to the wheel, rail and track.
A Model for the Contact Conditions at the Chip-Tool Interface in Machining
Authors: Ackroyd B. , Chandrasekar S. , Compton W. D.
Published: June 2003

A high-speed photographic study has been made of the chip-tool interface and its evolution when cutting pure metals with optically transparent sapphire tools. The use of a high speed camera in conjunction with an optical microscope has enabled details of the interface, including the velocity field along the interface, to be resolved at high spatial and temporal resolution while cutting at speeds between 1 mm/sec and 2000 mm/sec. The results show the chip-tool contact along this interface to be composed of four distinct regions: a region of stagnation at the cutting edge, a region of retardation adjoining the stagnation region, a region of sliding beyond the retardation region, followed by a region of metal transfer or “sticking” that is located furthest away from the cutting edge alongside the boundary of the contact. The chip and tool appear to be in intimate contact over the stagnation, retardation, and sliding regions, with sliding occurring at the interface over much of this zone of intimate contact. These observations have provided direct experimental evidence for a model of the contact conditions proposed by Enahoro and Oxley based on analytical considerations. Cutting experiments with non-oxide tools such as aluminum and high speed steel suggest that this description conditions is equally applicable to tool materials other than sapphire.
A Lubricant Model Considering Wall-Slip in EHL Line Contacts
Authors: Sta˚hl Jonas , Jacobson Bo O.
Published: June 2003

A wall-slip model including limiting shear stress and the occurrence of slip at the interfaces between the lubricant and the adjacent surfaces is presented. The lubricant model is applied to EHL line contacts using smooth surfaces and isothermal conditions. The main part of the model concerns the lubricant velocities at the surfaces that are decoupled from the corresponding surface velocity giving two new variables in the EHL equations. The lubricant velocities at the surfaces are related to the corresponding shear stresses. As long as the value of the shear stress is below the limiting shear stress, the lubricant velocity is equal to the surface velocity. However, when the shear stress reaches the limiting shear stress, interfacial slip appears and the lubricant velocity differs from the surface velocity. Some initial results are presented and compared to a Newtonian analysis.
Effect of Lubricant Protein Concentration on the Wear of Ultra-High Molecular Weight Polyethylene Sliding Against a CoCr Counterface
Authors: Saikko Vesa
Published: June 2003

In the wear testing of prosthetic joints, the optimal lubricant protein concentration is disputed. The effect of protein concentration of calf serum based lubricant on the wear of ultra-high molecular weight polyethylene against CoCr was studied with a 12-station, circularly translating pin-on-disk device. The wear factor first steeply increased with increasing concentration, reached a peak at 10–20 mg/ml, and then slowly decreased. Below 20 mg/ml, the wear mechanisms were not entirely representative of clinical wear. Above this value, the morphology of the UHMWPE wear surface resembled that of retrieved cups. The results indicated that the concentration should not be below 20 mg/ml. The scope of this recommendation is discussed.
Mechanism of Action of Colloidal Solid Dispersions
Authors: Chin˜as-Castillo F. , Spikes H. A.
Published: June 2003

In the past there has been considerable interest in the possibility of using liquid lubricants containing dispersed, solid particles in the 1–50 micron size range to reduce friction and wear. These particles are used in greases and some industrial oils. Researchers are now directing their attention to the behavior of much smaller colloidal particles in the range of 5 nm to 200 nm diameter. Such systems are formally known as “colloidal sols” and have been claimed to influence friction and wear. Further reasons for studying such colloidal particles is that they are present in soot-contaminated engine lubricating oils, as wear debris and as partially-soluble additives. Thus, the objective of the work derived in this paper was to investigate the mechanism of action of colloidal solid particles in the range of 5 to 200 nm diameter in lubricating oils. Of particular interest was the effect of slide-roll ratio on particle entrainment and the influence of the ratio of particle diameter to elastohydrodynamic lubricant film thickness on particles’ behavior. This study has shown that in thin film contacts, colloid nanoparticles penetrate EHD contacts mainly by a mechanism of mechanical entrapment. It is found also that in rolling contacts at slow speeds, colloids formed a boundary film of at least 1 or 2 times the particle size. This film influence friction and wear. However, this film is lost at high speed and the film thickness reverts to the colloid-free fluid. The results of this study have enabled a mechanism of lubricating action by colloid sols to be derived.
Experimental and Theoretical Study of Instantaneous Engine Valve Train Friction
Authors: Mufti Riaz A. , Priest Martin
Published: June 2003

A new method has been developed to directly measure valve train friction as a function of crank angle using specially designed timing belt pulley torque transducers fitted to the inlet and exhaust camshafts of a single-cylinder gasoline engine. Simultaneous and instantaneous friction torque of both the inlet and exhaust camshafts at any engine speed can be measured, with no apparent detrimental effect of timing belt loading on the output reading. Experiments are reported for valve train friction at a range of motored engine operating conditions with different lubricant formulations, with and without a friction modifier. These are compared with the predictions of an existing valve train friction model based upon elastohydrodynamic lubrication theory. Measured friction decreased with increasing engine speed but increased with increasing oil temperature and the fuel economy benefit of friction modifiers was observed. The model yielded similar magnitudes of friction at medium engine speeds and above but predicted much lower friction with high oil temperatures at low speed. Comparison of theory and experiments also suggests that some oil may leak from hydraulic lash adjusters during the cam event with a consequent reduction in geometric torque.
A Semi-Analytical Solution for the Sliding Inception of a Spherical Contact
Authors: Kogut Lior , Etsion Izhak
Published: June 2003

A finite element analysis, for an elastic perfectly plastic sphere normally loaded by a rigid flat, is combined with an approximate analytical solution to evaluate the maximum tangential load (static friction) that can be supported by the spherical contact at the inception of sliding. Sliding inception is treated as a failure mechanism based on plastic yield rather than a Coulomb friction law with a certain friction coefficient. Two different failure modes are identified, either on the contact area or below it, depending on the elastic-plastic status of the normal preloading. A limiting normal preload is found above which the contact cannot support any additional tangential load. Simple analytical expressions for an “internal static friction coefficient” are presented for both the elastic and the elastic-plastic regimes.
A Friction Model for Cold Strip Rolling With Two-Wavelength Surface Roughness in the “Mixed” Lubrication Regime
Authors: Le H. R. , Sutcliffe M. P. F.
Published: June 2003

A two-dimensional friction model has been developed for cold metal rolling in the “mixed” lubrication regime. Roughness is modelled using superimposed short and long wavelength asperities with a lay orientated along the rolling direction. The hydrodynamic pressure in the lubricant is solved using Reynolds’ equation, coupled with the crushing process of the two-wavelength roughness. This allows for the solution of film thickness and contact area ratio and hence friction coefficient through the roll-bite. The model extends the authors’ earlier model [15] by allowing for a variation in hydrodynamic pressure across the width of the contact. Predictions for both the surface roughness and the friction coefficient are in reasonable agreement with published measurements.
Traction Drive With Reduced Spin Losses
Authors: Cretu O. S. , Glovnea R. P.
Published: June 2003

The paper focuses on the effect of spin motion upon elastohydrodynamic (EHD) traction in a CVT traction drive. The effect of the spin is determined upon the traction curves, traction coefficient and the slope of linear section of the traction curves. A kinematic study of a standard EHD contact leads to the general formula that governs the spin motion within the area of contact. Subsequently, this equation is applied to a traction drive with conical discs, balls and support ring. Furthermore it is determined that the spin motion at the contacts between balls and supporting ring creates additional loss. A new, original type of supporting ring that may ameliorate the spin loss is presented. This new support ring changes the type of contact between balls and supporting ring by replacing one heavily loaded contact between a ball and the ring with two spin-optimized contacts.
Modeling of Line Contacts With Degrading Lubricant
Authors: Kudish Ilya I. , Airapetyan Ruben G.
Published: June 2003

A plane isothermal elastohydrodynamic problem for a lubricated line contact is studied. The lubricant represented by a base stock with some polymer additive undergoes stress-induced degradation due to scission of polymer additive molecules. The polymer molecules have linear structure. The degradation process of a polymer additive dissolved in a lubricant while the lubricant passes through the contact is described by a kinetic equation. The kinetic equation is solved along the lubricant flow streamlines. The solution of the kinetic equation predicts the density of the probabilistic distribution of the polymer molecular weight versus polymer molecule chain length. The changes in the distribution of polymer molecules affect local lubricant properties. In particular, the lubricant viscosity changes as polymer molecules undergo scission. These irreversible changes in the lubricant viscosity alter virtually all parameters of the lubricated contact such as film thickness, frictional stresses and pressure. As a result of the polymer additive degradation the lubricant experiences a significant viscosity loss. The viscosity loss (up to 60 percent), in turn, leads to a noticeable reduction in the lubrication film thickness (up to 12 percent) and frictional stresses applied to contact surfaces in comparison with the case of a nondegrading lubricant. Moreover, the pressure distribution in degrading lubricants exhibits extremely sharp spikes of about 2.15 to 2.82 (depending on the slide-to-roll ratio) times greater than the maximum Hertzian pressure. That may lead to noticeable variations in fatigue life of the contact surfaces.
Molecular Dynamics Simulation of Vibrational Friction Force Due to Molecular Deformation in Confined Lubricant Film
Authors: Tanaka Kentaro , Kato Takahisa , Matsumoto Yoichiro
Published: June 2003

The lubrication by thin film has become a very important role in micro machine, magnetic storage device and so on. As the thickness of lubricant film becomes thinner to several nanometers, the conventional law of lubrication becomes unable to use. Nonequilibrium molecular dynamics simulation (NEMD) was carried out to investigate the dynamic behavior of thin lubricant film confined between walls. The model used in these simulations is composed of two solid walls and fluorocarbon polymer lubricant. One of the walls is supporting a load and at the same time moving at constant velocity. Results indicate that the frictional behavior of confined lubricant varied with load; velocity field in the film retain liquid like structure under low load conditions, on the other hand, under high load conditions lubricant film becomes solidified and periodical stick and slip motion is observed at the layer near the wall. At the same time periodically vibrating friction force is observed. In this case, radius of gyration of lubricant molecules also changes periodically. It is concluded that the periodical vibration of friction force is caused by stick-slip with molecular deformation.
The Effects of Three-Dimensional Model Surface Roughness Features on Lubricant Film Thickness in EHL Contacts
Authors: Choo Jian W. , Glovnea Romeo P. , Olver Andrew V. , Spikes Hugh A.
Published: June 2003

The Spacer Layer Imaging method has been used to investigate the influence of three-dimensional roughness features on the thickness and shape of elastohydrodynamic (EHL) films. An array of near-hemispherical bumps was employed to represent asperities. A micro-EHL film developed at the bumps whose orientation depended on that of the inlet boundary at the location at which the bump had entered the contact. Rolling-sliding conditions induced a micro-EHL film with a classical horseshoe shape at the bumps. The flow of lubricant around the bumps appeared to differ between thin and thick films.
Analysis of a Ball Bearing With Waviness Considering the Centrifugal Force and Gyroscopic Moment of the Ball
Authors: Jang G. H. , Jeong S. W.
Published: June 2003

This research presents an analytical method to calculate the characteristics of the ball bearing under the effect of the waviness in its rolling elements and the centrifugal force and gyroscopic moment of ball. The waviness of rolling elements is modeled by using sinusoidal function, and the centrifugal force and gyroscopic. moment of ball are included in the kinematic constraints and force equilibrium equations to produce the nonlinear governing equations. To improve the convergence of the numerical solution of the nonlinear governing equations, it includes the derivatives of the gyroscopic moment and load-deflection constant of each race in the Newton-Raphson formulation. The accuracy of this research is validated by comparing with the prior research, i.e., (i) the contact force, contact angle in case of considering only the centrifugal force and gyroscopic moment of ball, and (ii) the contact force and vibration frequencies in case of considering only the waviness, respectively. It investigates the stiffness, contact force, displacement and vibration frequencies of the ball bearing, considering not only the centrifugal force and gyroscopic moment of ball but also the waviness of the rolling elements.
New First and Second Order Slip Models for the Compressible Reynolds Equation
Authors: Wu Lin , Bogy D. B.
Published: June 2003

In the original derivations of the first order and the second order slip models of the generalized Reynolds equation in the literature [3,4], a length scale equal to the mean free path of the gas molecules was used in a Taylor series expansion of the mean velocity field. The coefficients of the correction terms in the derived lubrication equation depend on that length scale. This choice of the length scale is arbitrary to some extent. In this paper, new first order and the second order slip models are derived using a somewhat more physical approach, in which the requirement that the expansion length scale be the mean free path is relaxed. In this approach the momentum transfer rate across each surface element is obtained by summing up the contributions from each group of molecules impinging on the surface at an angle θ to the surface normal within a solid angle dω. The new second order slip lubrication equation appears to be preferable to the original one when the inverse Knudsen number is small, and it is free of any contact pressure singularity, whereas the new first order slip model continues to contain the unacceptable pressure singularity in the limit as the spacing approaches zero, as does the original first order model.