bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of ball size variation on vibrations associated with ball-bearings
Authors: Aktärk N , Gohar R
Published: October 2002

In this paper the radial and axial vibrations of a rigid shaft supported by a pair of angular contact ball-bearings is studied. The effect of ball size variation in the bearings on the vibration of the shaft is investigated. A computer program was developed to simulate this effect, with the results presented in time and frequency domains. All results show that off-sized balls in the bearing cause vibrations at cage speed and its harmonics, depending on their arrangement within the bearing. Symmetric combinations will produce vibrations at the multiples of the cage speed and all other combinations will produce vibrations at the cage speed. The highest radial vibrations due to ball size variation are at a speed of half of the number of balls times the cage speed.
Improved effectiveness of vibration monitoring of rolling bearings in paper mills
Authors: Al-Najjar B
Published: October 2002

Rolling element bearing failures in paper mill machines are considered in relation to their critical role in the machine function. The paper discusses these failures according to what becomes damaged and how, and relates them to the vibration spectra and their development over the lives of the bearings. Interpretations of some variations in the vibration signature, i.e. relating vibration amplitude changes and frequency shifts to the deterioration processes involved, are proposed and discussed. The literature was found mainly to confirm this analysis. A new approach to envelope alarming is presented and shown theoretically (logically) to offer later renewal with fewer failures, and therefore lower cost and higher productivity. Deficiencies in data coverage and quality, and the feedback of case study results, are discussed. A model to improve maintenance experience is proposed and discussed. Using vibration to monitor component conditions, the accurate prediction of remaining life requires (a) enough vibration measurements, (b) numerate records of operating conditions, (c) better discrimination between frequencies in the spectrum and (d) correlation of (b) and (c). This is because life prediction depends on the amplitudes of (and) the frequencies generated by the component damage. Much money could be saved because some of the present policies utilize as little as half of the useful life of a bearing.
Molecular dynamics simulation of ultra-thin lubricating films
Authors: Hu Y-Z , Wang H , Guo Y , Zheng L-Q
Published: October 2002

Molecular dynamics simulation has been performed in the present study for a Lennard-Jones (LJ) fluid in Poiseuille flow to examine the Theological behaviour of ultra-thin lubricating films. The results show that as two solid walls continuously approach each other, the effective viscosity of the confined fluid increases and goes towards divergence; the critical pressure of the phase transition declines as the film thickness reduces; when the separation exceeds ten molecular layers, however, the pressure curve slopes gently and tends to an asymptotic value-the bulk transition pressure of the lubricant; and an in-plane ordering structure will develop in the film, which originates from the wall-fluid interface and grows towards the middle of the film as the system pressure increases. It is concluded that the rheological performance of the lubricant may become film thickness dependent and a solid-liquid transition may be induced when the film is molecularly thin.
Modelling of mixed hydrodynamic and boundary lubrication: Layered structures and shear thinning
Authors: Jang S , Tichy J. A.
Published: October 2002

This paper is concerned with an intermediate regime between boundary and hydrodynamic lubrication. With high molecular weight polymer lubricants, it is accepted that polymeric molecules stick to the boundary surfaces in the form of immobile solid-like layers whose thickness may be of the order of 50 nm. Such layers may comprise about half of the minimum film thickness under severe sliding conditions. In addition, shear thinning may occur in a central region of the film, away from the thickened layers. From this physical picture, a modified Reynolds equation is developed which depicts an immobile layer model representing molecular microstrucrure and a shear thinning effect away from the surface. Compared to the Newtonian case, the molecular microstructure causes much higher pressure levels. This result is consistent with the physical idea that slow sliding speeds can apparently generate sufficient forces to separate surfaces in boundary lubrication conditions, although the classical hydrodynamic theory would predict otherwise.
Studies on rubber wear
Authors: Zhang S. W.
Published: October 2002

Achievements in research on rubber wear by the present author and his group over the past ten years are summarized briefly. These results include mechanisms and wear equations for dry and wet abrasion, basic features and wear mechanism of oily abrasion, theory of dry abrasion by a line contact, physical processes and surface mechanochemical effects of abrasive erosion. They are not only significant in the context of rubber tribology but are also valuable for extending the working life of rubber components.
Surface engineering of titanium alloys for wear protection
Authors: Bloyce A
Published: October 2002

This paper describes the reasons for the generally poor tribological behaviour of titanium alloys. It describes surface engineering processes currently used in the protection of titanium alloy surfaces against wear including plasma spraying, physically vapour-deposited coatings, electrolytic and electroless plating, ion implantation and anodizing. The advantages and disadvantages of the various processes are indicated and typical components treated by these processes are described.

Thermochemical processes and energy beam alloying surface engineering processes applied to titanium alloys are described in greater detail. Contemporary research and development in these areas are described, particularly where the objective is the production of surface hardening to depths comparable with those used in conventional transmission materials such as in nitrided steels.
A simple method of stress intensity factor calculation for inclined fluid-filled surface-breaking cracks under contact loading
Authors: Fletcher D I , Beynon J H
Published: October 2002

A simple method has been developed for the calculation of stress intensity factors for fluid-filled cracks under contact loading (typical of rolling contacts) and results compare well with existing data from more complex models.
The effect of the white layer on micro-pitting and surface contact fatigue failure of nitrided gears
Authors: Bull S J , Evans J T , Shaw B A , Hofmann D A
Published: October 2002

The effect of the ‘white layer’ in nitrided steel on micro-pitting of gears has been investigated by comparing the performance of case carburized and nitrided gears fabricated from modern, low-oxygen steels. It is shown that the white layer, produced during nitriding, imparts a high resistance to micro-pitting. Because surface contact fatigue is nucleated at micro-pits in low-oxygen steels, the resistance to micro-pitting also manifests itself in a higher fatigue resistance for the nitrided material.
An energy balance of high-speed abrasive water jet erosion
Authors: Momber A. W. , Kovacevic R
Published: October 2002

High-speed abrasive water jetting is an alternative tool for machining engineering materials. The energy dissipation processes involved in this erosion process have not been investigated systematically. In this paper, a model is developed to calculate the energy dissipation in workpieces eroded by abrasive water jets. By introducing an energy dissipation function χ(Φ). the model enables the estimation of the energy absorption as a function of the erosion depth. The energy dissipation function can be expressed by a second-order polynomial approximation. Measurements of the reaction forces on the exiting slurry after the erosion process, material removal experiments and fracture tests are conducted to separate the components of the energy dissipation parameter, such as damping, friction and erosion debris generation.
Correction for pressure dependence of the refractive index in measurements of lubricant film thickness with image analysis
Authors: Marklund O , Gustafsson L
Published: October 2002

The lubricant film thickness between contacting bodies may be determined from interferograms by image analysis. Look-up tables employed in the analysis are obtained from calibration interferograms of contacts of bodies of known shape. Calibration and measurement interferograms are, however, obtained under different pressure conditions and, since the refractive index of lubricants is pressure dependent, the use of look-up tables can introduce significant errors (in the range of 10 per cent).

In this paper it is shown that a straightforward correction for this error is available. In an iterative procedure the uncorrected film thickness is first determined through looking up tables. This allows the pressure distribution over the contact to be calculated and a corrected refractive index may then be obtained. The corrected refractive index in turn allows a corrected film thickness to be calculated. This procedure can be followed iteratively. After two iterations the corrections have been found to be of the same order as the resolution yielded by the method, as has been implemented.
Generation of magnetic tape debris and head stain in a linear tape drive
Authors: Scott W. W. , Bhushan B
Published: October 2002

The presence of tape debris at the head-tape interface can cause an increase in spacing and consequently an increase in signal loss. In this study, the generation of tape debris in linear tape drives is analysed. Functional drive tests are conducted using thin-film AlO3-TiC and Ni-Zn ferrite heads run against commercial metal particle (MP) tape. Three types of tape debris are found: magnetic particle rich, polymer rich and adherent (stain). Each type is found at a distinct location on the head surface. Optical microscopy and computerized image analysis are used both to quantify the tape debris and to find its distribution on the head. Atomic force microscopy is used to measure the thickness of adherent debris. The Al2O3-TiC sample generates more of all three types than does the Ni-Zn ferrite sample. This is probably a result of the higher hardness of Al2O3-TiC. The differential wear of Al2O3 and TiC probably accounts for the presence of adherent debris on the Al2O3-TiC head. No adherent debris can be found on the Ni-Zn ferrite head. Since the adherent debris collects near the pole tip and is difficult to remove, it potentially poses the greatest head-tape spacing problem, even though its thickness is only of the order of a few nanometres. A relationship is found between the generation of loose debris and the tape speed, tape tension and head wrap. Loose debris generation increases as the tape speed decreases and as the tape tension and head wrap increase. Its generation is found to be approximately proportional to the frictional force. Loose debris, especially the magnetic-particle-rich type, continues to be generated in abundant amounts beyond the burnishing phase for MP tape. The use of an abrasive tape leader is found to reduce the amount of debris at the interface.
Torsional vibration of a back-to-back gearbox rig Part 1: Frequency domain modal analysis
Authors: Leishman B A , Drew S J , Stone B J
Published: October 2002

The torsional vibration of a back-to-back gearbox system has been investigated experimentally and analytically. Gearboxes are typically part of a larger system, or drivetrain, which commonly includes electric motors, shafts, couplings, ball mills, turbines and generators. The dynamics of the system has been shown significantly to influence the gearbox response and requires inclusion in gearbox modelling. Assumptions are commonly made, however, to reduce the degrees of freedom of the model, and system dynamics is subsequently neglected. Receptance methods were applied to model a back-to-back gearbox system and were shown to be an effective modelling technique for geared system analysis. A detailed experimental modal analysis was performed using the swept-sine technique with an a.c. servomotor torsional exciter. Torsional excitation allowed for the dynamic response to be measured up to 1600 Hz. A multi-degree-of-freedom, frequency domain torsional model of the gearbox system was developed using receptances. The model included a combination of lumped-mass elements, and continuous shafts with distributed inertia and hysteretic damping. The modelled torsional natural frequencies were matched to the measured frequencies by the adjustment of system model parameters to achieve a high level of agreement. Matching of system natural frequencies resulted in the accurate prediction of the first nine associated torsional deflected shapes up to 1548 Hz. This paper presents the detailed results of a full torsional, modal analysis of a gearbox system, demonstrating receptance system modelling and an effective method for torsional excitation on rotating machines.
Closed-form solution for response of linear systems subjected to periodic non-harmonic excitation
Authors: Chicurel-Uziel E
Published: October 2002

A scheme is proposed for linking together into a single equation the equations and inequalities that make up a piecewise representation of a non-harmonic, periodic, continuous or discontinuous function. A method using this scheme is proposed in order to obtain, in closed form, the displacement response of linear vibration problems with piecewise-continuous forcing functions. Since the solution is exact, so are the derivatives, i.e. the velocity and acceleration responses. An example is presented.
The modelling and simulation of vehicle handling Part 4: Handling simulation
Authors: Blundell M V
Published: October 2002

This is the last in a series of four papers (Parts 1 to 4) looking at the application of computer-based analysis methods to model vehicles and simulate vehicle handling. The material contained in these papers is based on a study carried out in order to investigate the influence of suspension and tyre modelling on the outputs predicted by vehicle handling simulations. The papers deal with analysis methods, vehicle modelling, tyre modelling (which appeared in the previous two Issues) and handling simulation.

In this paper an example of a vehicle handling simulation based on a high-speed lane change manoeuvre is presented. The effects of suspension modelling on the accuracy of simulation outputs is discussed on the basis of results obtained using the four vehicle models described in Part 2 of this series. Measured outputs such as lateral acceleration and roll angle are compared with measurements taken from the vehicle during the same manoeuvre on the proving ground. The influence of the tyre models described in Part 3 on the simulation outputs is shown. The effects of vehicle and tyre modelling on computer simulation time are also summarized. The paper concludes by demonstrating how a simple vehicle and tyre model can be used to carry out sensitivity studies varying vehicle and tyre design parameters.
A time integration method for simulations of tyre vehicles on flexible structures
Authors: Friberg O , Möller P , Thorvald B
Published: October 2002

The main objective was to perform simulations using a realistic model of a truck and trailer passing over a flexible bridge structure. A general multi-body dynamics program, DADS, and its tyre subroutines were interfaced with in-house finite element method (FEM) routines in order to create a vehicle/structure interaction computer program. Different time stepping algorithms from multi-body dynamics and FEM domains were integrated into a ‘common’ time stepping procedure. The bridge structure was simplified to a flat surface built up of shell finite elements. Tyre normal, lateral and longitudinal forces were applied to the bridge. Three driving cases were considered: straight forward driving with and without braking and a lane change manoeuvre. Braking moments were distributed to the wheel axles. The program ANSYS was used for post-processing of bridge stresses.
The Theory of screws incorporated in a new finite element
Authors: Sabourin F , Fayet M , Vives M
Published: October 2002

The new finite element studied here is of triangular type and is used in sheet stamping simulation. The number of equilibrium equations is half that of known methods owing to an original displacement description. The new trianglular element does not use any nodal rotation, and only the translations are useful. This is allowed by the theory of screw elements, which transform a case of rotation into a translational displacement with an offset, and by analogy with a system of rigid bodies. All the steps of the method are presented up to the evaluation of the stiffness matrix. Some examples of simulations are then given.
Dynamic behaviour of large helical gears
Authors: Haigh J , Fawcett J N
Published: October 2002

Inertia forces resulting from small changes in velocity ratio between pinion and wheel excite gear noise and vibration. These are caused by a combination of geometric errors and variable elastic mesh deflections. The forces are transmitted through the bearings to the gearbox structure, and so either generate airborne noise or lead to excitation of other structures. In this investigation of gear noise, the dynamic forces excited at the bearing at tooth contact frequency (TCF) are considered as the ‘noise parameter’. This has been used to compare gears of differing geometry at varying load and speed conditions. The test programme is based on typical, large face width, marine propulsion gears running in the UK 8 MW gear noise test rig at the University of Newcastle.
Influence functions for usual fourth-order homogeneous linear ordinary differential equations
Authors: Zhang Y S
Published: October 2002

Influence functions in various situations are derived. They are very useful for solving problems of static buckling, stability and vibration of elastic bodies. Some of them have been utilized to research vibrations of beams, thin-walled bars, shells and plates.
Eclipse-RP: A new RP machine based on repeated deposition and machining
Authors: Kim J , Cho K S , Hwang J C , Iurascu C C , Park F C
Published: October 2002

This paper presents a newly developed rapid prototyping (RP) machine. The design of this machine is based on the Eclipse parallel mechanism invented by the authors. One of the advantages of the Eclipse mechanism as compared to Gough-Stewart-based parallel mechanisms and applied to machining processes is that the spindle can tilt to 90 degrees and enables five-face machining without any set-up change of the workpieces. This advantage has been fully utilized in designing the new RP machine. The RP process consists of four stages: (1) post-machining feature extraction, (2) the slicing of the deposition feature, (3) repeated deposition and machining of each sliced layer, and (4) post-machining. Whole stages are executed in one machine structure without any set-up change. Using the Eclipse-RP and standard test parts, remarkable gains in productivity are obtained, namely 2.5 times reduction in time and 8 times reduction in cost.
Virtual prototyping of parallel mechanisms
Authors: Bianchi G , Tosatti L Molinari , Fassi I
Published: October 2002

Industrial adoption of parallel kinematic machines (PKMs) may be eased by the availability of methodologies and integrated tools able to analyse in a short time PKMs of any architecture, providing the key data needed to design the machine. The proposed virtual prototyping environment (VPE) meets these requirements, quickly estimating not only the reachable workspace, and the kinetostatic behaviour, but also the actuator effort, internal loads in the mechanical structure and the effects of lumped structural compliances and of manufacturing/assembling errors. A description of the developed VPE-PKM, based on a commercial multi-body package, is given. Its effectiveness is shown by presenting results obtained by ITIA-CNR during the design of a three-degrees-of-freedom (3DOF) translational PKM for light deburring operations, and comparing them with experimental data.
A study of the effects of the lower index methods on ADAMS sparse tableau formulation for the computational dynamics of multi-body mechanical systems
Authors: Orlandea N V
Published: October 2002

This paper studies the effects of reducing the index of the original ADAMS (automatic dynamic analysis of mechanical systems) formulation. For this, a pilot computer program MECH-SIM (MECHanical SIMulations) was developed on the basis of the original ADAMS attributes such as sparse tableau formulation (STF) and backward difference formula (BDF) [1].

The STF implemented in the original ADAMS computer program uses differential and algebraic equations (DAE). In the new formulation it eliminates the three relations connecting the body angular velocities and the angular momentum. It also reformulates the implicit force equations by substituting their functions directly into the corresponding differential equations of motion. The above reduction maintains a reasonable number of equations when the geometric constraints stabilize the velocity and/or the acceleration constraints. A method is found to measure ‘the drift’ allowed by the velocity or acceleration constraints. This permits the use of constraints stabilization only ‘when needed’. Consequently, the BDF error control improves maintenance of the efficiency of the method.

The pilot computer program MECH-SIM incorporates these improvements. The program was used to test the numerical accuracy and efficiency on mechanical systems used in agricultural mechanization, industrial equipment and auto suspensions. Hence, such results can be extended to the modern ADAMS computer program.
Efficient modelling and analysis for crankshaft three-dimensional vibrations under firing conditions
Authors: Okamura H , Morita T
Published: October 2002

The three-dimensional vibrations of an engine crankshaft system under firing conditions were investigated by simple modelling and analysis using the dynamic stiffness matrix method (DSMM). In the analyses, the authors took account of the dynamic behaviour of cylinder block, oil film and torsional damper. To simplify the analyses, the crankshaft was idealized by a set of jointed structures consisting of simple round rods and simple beam blocks of rectangular cross-section. The main journal bearings were idealized by a set of linear springs and dash-pots, and the flywheel was modelled by finite elements. Then the dynamic stiffness matrix (DSM) was derived in closed form for each constituent member.

To eliminate the complicated finite element method (FEM) analysis for a cylinder block of complicated structure [1,2], the authors derived the dynamic stiffness matrix from the inverse matrix of the compliance matrix. Here, the compliance matrix was derived in analytical form from the modal parameters obtained from a series of hammering tests. Finally, the dynamic stiffness matrix was constructed for the total engine system consisting of the crankshaft system and the cylinder block.

The three-dimensional vibrations of the crankshaft system and cylinder block surface vibrations near the main bearings under firing conditions were calculated for an automobile diesel engine in which five kinds of solid pulley, each with different masses and moments of inertia, and a torsional damper were attached to the crankshaft. The calculated results were compared with the experimental results.
Mechanical properties of some Swedish hard wood species
Authors: Gustafsson S-I
Published: October 2002

A large part of Sweden is located within the Taiga Area and hence most of the wood species growing there are included in the division of Coniferales. This has also led to major research activities on the needle-leaved types in the Pinaceae family. There are, however, many broad-leaved trees, but because of their relatively low economic importance only a few researchers have had the opportunity to study such woods. For certain branches of the Swedish wood manufacturing industry the Angiosperms are of vital importance, e.g. the furniture factories. In this paper the mechanical properties of two Swedish hard wood genera, namely Betula and Alnus, are revealed. These findings are also compared with those found in the literature.
Mixture preparation strategies in an optical four-valve port-injected gasoline engine
Authors: Gold M. R. , Arcoumanis C , Whitelaw J. H. , Gaade J , Wallace S
Published: October 2002

The mixture formation in a single-cylinder, optical port-injected gasoline engine was investigated for both closed- and open-valve injection strategies with a combination of phase Doppler anemometry, laser-induced fluorescence and Mie scattering and correlated with combustion development and exhaust emissions. Detailed crank angle resolved data of the flow and mixture distribution during induction and compression have revealed the advantages of early open-valve injection, in terms of extending the lean limit and maintaining satisfactory engine performance and HC/NOx emissions, achieved through charge stratification in the vicinity of the spark plug at the time of ignition.
The effects of exhaust gas recirculation on diesel combustion and emissions
Authors: Ladommatos N , Abdelhalim S , Zhao H
Published: October 2002

An investigation was conducted with the aim of identifying and quantifying the effects of exhaust gas recirculation (EGR) on diesel engine combustion and exhaust emissions. Five effects of EGR were identified and investigated experimentally: the reduction in oxygen supply to the engine, participation in the combustion process of carbon dioxide and water vapour present in the EGR, increase in the specific heat capacity of the engine inlet charge, increased inlet charge temperature and reduction in the inlet charge mass flowrate arising from the use of hot EGR. The experimental methodology developed allowed each one of these effects to be investigated and quantified separately. The investigation was carried out on a high-speed, direct injection diesel engine, running at an intermediate speed and load. A limited number of tests were also conducted in an optically accessible diesel engine, which established the effects of EGR on local flame temperature. Finally, tests were conducted with simulated EGR being used additionally to the engine air supply. This contrasts with the conventional use of EGR, whereby EGR replaces some of the air supplied to the engine.

It was found that the first effect of EGR (reduction in the oxygen flowrate to the engine) was substantial and resulted in very large reductions in exhaust NOx at the expense of higher particulate emissions. The second and third effects (participation of carbon dioxide and water vapour in the combustion process and increase in the charge specific heat capacity) were almost insignificant. The fourth effect (higher inlet charge temperature) increased both exhaust NOx and particulate emissions. The fifth effect (reduction in the inlet charge due to thermal throttling) reduced NOx but raised particulate emission. Finally, when EGR was used additionally to the inlet air charge (rather than displacing air), substantial reductions in NOx were recorded with little increase in particulate emission.
Predictions of tumble and turbulence in four-valve pentroof spark ignition engines
Authors: Achuth M , Mehta P S
Published: October 2002

A predictive model for tumble charge motion and turbulence in four-valve pentroof engines has been developed. The model formulation is based on a mean flow analysis of tumble motion in conjunction with k-∊ turbulence equations. All major phenomena, including fluid shear, affecting mean vortex behaviour and turbulence generation are included. The predictions are made for both intake and compression periods of the engine cycle. The model predictions have been compared with earlier analytical investigations in two engines and are found to be in good qualitative and quantitative agreement. The distinct stages characterizing mean vortex and its turbulence have been identified in this work. Further, the mechanism responsible for turbulence enhancement through tumble has been synthesized and related to these stages.

A preliminary parametric study with intake valve lifts and pentroof angles is carried out to demonstrate the capability of the model in design studies. It is revealed that a large-angled pentroof retains significant vortex structures even at top dead centre. In an optimized geometry, these structures may play a role in improving overall mass burn rates. The chamber geometry is found to have a significant influence on bulk motion and turbulence levels at ignition. The intake system, however, influences the formation of tumble vortices during the intake stroke.
Tumbling flow analysis in a four-valve spark ignition engine using particle image velocimetry
Authors: Li Y , Zhao H , Peng Z , Ladommatos N
Published: October 2002

Tumble motion in the cylinder of a four-valve spark ignition (SI) engine with a production-type cylinder head was studied using cross-correlation digital particle image velocimetry (PIV). The in-cylinder flow field was measured on three planes: the vertical symmetric plane of the combustion chamber, the vertical plane through centres of the intake and exhaust valves, and a horizontal plane 12 mm below the cylinder head. Ensemble-averaged mean velocity, velocity fluctuation distribution and cyclic variation of the instantaneous velocity field were analysed. Analysis results show that the tumble vortex is formed in the early stage of the compression stroke and distorted in the late stage of the compression stroke. The tumble centre is nearly in the centre of the cylinder when the tumble forms. Then it moves gradually to the underneath of the exhaust valves as the piston moves up. It is found that the cyclic variation of the tumble motion at a tumble ratio of 0.9 is so great that the ensemble-averaged flow characteristics hardly represent any individual cycle flow behaviours. Distribution of the velocity fluctuation field is inhomogeneous during the whole compression process. As the engine speed changes the large-scale flow structure seems to remain unaffected.
Novel Method to Prepare Organosilane Monolayers on Solid Substrate
Authors: Kojio Ken , Tanaka Keiji , Takahara Atsushi , Kajiyama Tisato
Published: October 2002

A novel and convenient method to prepare organosilane monolayers was proposed. Pure water was put onto a cleaned silicon wafer and then a toluene solution of n-trichloro(octadecyl)silane (OTS) was spread on it. X-ray photoelectron spectroscopy and atomic force microscopic observation revealed that an OTS monolayer was successfully formed on the solid substrate after the water was evaporated. The static water contact angle of the silicon wafer covered with the OTS monolayer was 105°. Molecular aggregation states of the OTS monolayer were examined by electron diffraction, Fourier transform infrared spectroscopic, X-ray reflectivity, and grazing incidence X-ray diffraction measurements. The prepared OTS monolayer was in a two-dimensional hexagonal crystalline state at 293 K and alkyl chains of the OTS molecules were oriented normal to the surface. Also, the alkyl chains in the monolayer were highly ordered, although the experimental procedure for the monolayer preparation was quite simple. The development of this novel method to prepare a low energy surface will contribute to the material science as well as having industrial applications.
Reaction of HP(OC6H4NH)2 with n-BuLi and then with EX (E = Me, SiMe3, GeMe3, SnMe3, Cp(CO)2Fe, Cp(CO)ICo; X = Cl, I), Leading to Selective Deprotonation and Substitution
Authors: Kubo Kazuyuki , Nakazawa Hiroshi , Ogitani Yukihiro , Miyoshi Katsuhiko
Published: October 2002

The reaction of HP(OC6H4NH)2 with n-BuLi yielded the amide anion, HP(OC6H4NH)(OC6H4N−), with selective deprotonation at the nitrogen atom. Subsequent treatment of the anion with MeI yielded P-methylated phosphoranes: MeP(OC6H4NH)2 and MeP(OC6H4NH)(OC6H4NMe). In contrast, the reaction of the amide with ECl (E = SiMe3, GeMe3, SnMe3) led exclusively to N-substituted phosphoranes: HP(OC6H4NH)(OC6H4NE) and HP(OC6H4NH)2. In the corresponding reaction with (η5-C5H5)(CO)2FeCl, the anion was converted into a P-metalated phosphorane, (η5-C5H5)(CO)2Fe{P(OC6H4NH)2}, whereas the reaction with (η5-C5H5)(CO)CoI2 yielded an N-metalated phosphorane, HP(OC6H4NH)(OC6H4N{Co(η5-C5H5)(CO)I}]. The reason for such selectivity was discussed.
Isolation, X-ray Structural Characterization, and Reactivities of Diiodosamarium(II) Complexes Bearing Amide Compounds as Ligands
Authors: Nishiura Masayoshi , Katagiri Kosuke , Imamoto Tsuneo
Published: October 2002

The structures of diiodosamarium(II) complexes with amide compounds have been investigated basing on single crystal X-ray structural analyses. The reaction of [SmI2(thf)2] with 2 equivalents of tetramethylurea (TMU) gave [SmI2(thf)2(tmu)2] (1). The three different kinds of ligands in 1 attach to the samarium atom in a trans orientation. [SmI2(thf)2] reacted with 4 equivalents of 1,3-dimethyl-2-imidazolidione (DMI) to afford [SmI2(dmi)4] (2), forming a typical hexa-coordinated octahedral structure. Diiodosamarium complex containing four N,N-dimethylacetamide (DMA) ligands [SmI2(dma)4] (3) was prepared by treatment of [SmI2(thf)2] with 4 equivalents of DMA. The reaction of [SmI2(thf)2] with 6 equivalents of 1,3-dimethyl-3,4,5,6-tetrahydro-2-(1H)-pyrimidinone (dimethylpropyleneurea (DMPU)) gave [Sm(dmpu)6]I2 (4) quantitatively. This complex experiences a unique coordination fashion, in which six DMPU ligands coordinate to the samarium atom to overlap each other. [SmI2(dmpu)3(thf)] (5) was isolated from the reaction of [SmI2(thf)2] with 2 equivalents of DMPU. The reducing ability of these complexes was evaluated by reactions with benzylacetone or 9-haloanthracene. The structural analyses and reactivity studies of these complexes indicate that DMPU and DMA ligands are the most effective among the amide compounds to enhance the reducing ability of samarium diiodide.
Synthesis and Structural Characterization of Di-μ-Phenoxo-Bridged Dinuclear Iron(III) Complexes with Ferromagnetic or Weak Antiferromagnetic Coupling
Authors: Mikuriya Masahiro , Kakuta Yoshihisa , Nukada Ryoji , Kotera Takanori , Tokii Tadashi
Published: October 2002

Dinuclear phenoxo-bridged iron(III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H2La), N-salicylidene-2-hydroxy-5-chlorobenzylamine (H2Lb), and N-salicylidene-2-hydroxybenzylamine (H2Lc): [Fe2(La)2(CH3CO2)2] (1), [Fe2(La)2(C6H5CO2)2] (2), [Fe2(La){(CH3)3CCO2}2] (3), [Fe2(La)2{(C6H5O)2PO2}2] (4), [Fe2(La)2(CH3COCHCOCH3)2] (5), [Fe2(Lb)2(CH3CO2)2] (6), and [Fe2(Lc)2(CH3CO2)2] (7), have been synthesized and characterized by measurements of the infrared and electronic spectra as well as the magnetic susceptibilities. Single-crystal X-ray analysis has revealed that all of the complexes are dinuclear iron(III) complexes having a dinuclear iron(III) core bridged by two phenoxo-oxygen atoms of the Schiff-base ligands. The magnetic-susceptibility data show that a ferromagnetic interaction is operative within a dinuclear core in 1–4, 6, and 7 with J values ranging from 0.17(5) to 1.56(15) cm−1, whereas an antiferromagnetic coupling is operative in 5 with a J value of −9.24(6) cm−1. The magnetic properties are discussed in relation to the crystal structures.
Novel Chiral Fluorescent Labeling Reagent —4-Substituted 7H-benzo[de]benzoimidazo[2,1-a]isoquinolin-7-ones—
Authors: Nakaya Ken-ichi , Funabiki Kazumasa , Shibata Katsuyoshi , Matsui Masaki
Published: October 2002

(R)-4-(2-Hydroxy-1-phenylethylamino)-7H-benzo[de]benzoimidazo[2,1-a]isoquinolin-7-one was used as a fluorescent labeling reagent for Naproxen. The excitation and emission maxima of this reagent were observed at λ 453 and 508 nm in acetonitrile, respectively. This reagent reacted with racemic Naproxen in the presence of dicyclohexylcarbodiimide to afford the corresponding diastereomers, which were nicely separated in HPLC. The detection limit (S/N > 3) of Naproxen was ca. 5 fmol.
Channel selection methods for Infrared Atmospheric Sounding Interferometer radiances
Authors: Rabier Florence , Fourrié Nadia , Chafäi Djalil , Prunet Pascal
Published: October 2002

Advanced infrared sounders will provide thousands of radiance data at every observation location. The number of individual pieces of information is not usable in an operational numerical weather‐prediction context, and we have investigated the possibilities of choosing an ‘optimal’ subset of data. These issues have been addressed in the context of optimal linear estimation theory, using simulated Infrared Atmospheric Sounding Interferometer data. Several methods have been tried to select a set of the most useful channels for each individual atmospheric profile. These are two methods based on the data resolution matrix, one method based on the Jacobian matrix, and one iterative method selecting sequentially the channels with largest information content. The Jacobian method and the iterative method were found to be the most suitable for the problem. The iterative method was demonstrated to always produce the best results, but at a larger cost than the Jacobian method. To test the robustness of the iterative method, a variant has been tried. It consists in building a mean channel selection aimed at optimizing the results over the whole database, and then applying to each profile this ‘constant’ selection. Results show that this ‘constant’ iterative method is very promising, with results of intermediate quality between the ones obtained for the optimal iterative method and the Jacobian method. The practical advantage of this method for operational purposes is that the same set of channels can be used for various atmospheric profiles. Copyright © 2002 Royal Meteorological Society.
Tax Reform and Automatic Stabilization
Authors: Kniesner Thomas J , Ziliak James P
Published: October 2002

An income tax provides implicit insurance by dampening the variability of disposable income and consumption. Using an empirical framework derived from the consumption insurance literature and data from the Panel Study of Income Dynamics we examine the effect of federal income tax reforms of the 1980's on automatic stabilization of consumption. Overall, ERTA and TRA86 reduced consumption stability by about 50 percent. Recently increased EITC generosity restored or enhanced consumption insurance. The welfare cost of moving to the post-TRA86 system is sizable for relatively risk-averse households facing large income risk but is much more modest for the typical household.
Troubled Banks, Impaired Foreign Direct Investment: The Role of Relative Access to Credit
Authors: Klein Michael W , Peek Joe , Rosengren Eric S
Published: October 2002

During the 1980's, theories were developed to explain the striking correlation between real exchange rates and foreign direct investment (FDI). However, this relationship broke down for Japanese FDI in the 1990's, as the real exchange rate appreciated while FDI plummeted. We propose the relative access to credit hypothesis and show that unequal access to credit by Japanese firms contributes to the explanation of declining Japanese FDI. Using bank-level and firm-level data sets, we find that financial difficulties at banks were economically and statistically important in reducing the number of FDI projects by Japanese firms into the United States.
Technological Change, Technological Catch-up, and Capital Deepening: Relative Contributions to Growth and Convergence
Authors: Kumar Subodh , Russell R. Robert
Published: October 2002

We decompose labor-productivity growth into components attributable to (1) technological change (shifts in the world production frontier), (2) technological catch-up (movements toward or away from the frontier), and (3) capital accumulation (movement along the frontier). The world production frontier is constructed using deterministic methods requiring no specification of functional form for the technology nor any assumption about market structure or the absence of market imperfections. We analyze the evolution of the cross-country distribution of labor productivity in terms of the tripartite decomposition, finding that technological change is decidedly nonneutral and that both growth and bipolar international divergence are driven primarily by capital deepening.
Efficiency in Auctions with Private and Common Values: An Experimental Study
Authors: Goeree Jacob K , Offerman Theo
Published: October 2002

Auctions are generally not efficient when the object's expected value depends on private and common value information. We report a series of first-price auction experiments to measure the degree of inefficiency that occurs with financially motivated bidders. While some subjects fall prey to the winner's curse, they weigh their private and common value information in roughly the same manner as rational bidders, with observed efficiencies close to predicted levels. Increased competition and reduced uncertainty about the common value positively affect revenues and efficiency. The public release of information about the common value also raises efficiency, although less than predicted.
Insuring Consumption Against Illness
Authors: Gertler Paul , Gruber Jonathan
Published: October 2002

One of the most sizable and least predictable shocks to economic opportunities in developing countries is major illness. We investigate the extent to which families are able to insure consumption against major illness using a unique panel data set from Indonesia that combines excellent measures of health status with consumption information. We find that there are significant economic costs associated with major illness, and that there is very imperfect insurance of consumption over illness episodes. These estimates suggest that public disability insurance or subsidies for medical care may improve welfare by providing consumption insurance.
Plant-Level Irreversible Investment and Equilibrium Business Cycles
Authors: Veracierto Marcelo L
Published: October 2002

This paper evaluates the importance of microeconomic irreversibilities for aggregate dynamics using a real-business-cycle (RBC) model characterized by investment irreversibilities at the establishment level. The main finding is that investment irreversibilities do not play a significant role in an otherwise standard real-business-cycle model: Even though investment irreversibilities are crucial for establishment-level dynamics, aggregate fluctuations are basically the same under fully flexible or completely irreversible investment.
Sources of U.S. Economic Growth in a World of Ideas
Authors: Jones Charles I
Published: October 2002

Rising educational attainment and research intensity in recent decades suggest that the U.S. economy is far from its steady state. This paper develops a model reconciling these facts with the stability of U.S. growth rates. In the model, long-run growth arises from the worldwide discovery of ideas, which depends on population growth. Nevertheless, constant growth can temporarily proceed at a faster rate, provided research intensity and educational attainment rise steadily over time. Growth accounting reveals that these factors explain 80 percent of recent U.S. growth, with less than 20 percent coming from world population growth.
Machiavellian Privatization
Authors: Biais Bruno , Perotti Enrico
Published: October 2002

We analyze politically motivated privatization in a bipartisan environment. When median-class voters a priori favor redistributive policies, a strategic privatization program allocating them enough shares can induce a voting shift away from left-wing parties whose policy would reduce the value of shareholdings. To induce median-class voters to buy enough shares to shift political preferences, strategic rationing and underpricing is often necessary. In the extreme, this may lead to free share distribution and voucher privatization. Shifting voting preferences becomes impossible when strong ex ante political constraints require large upfront transfers to insiders or when social inequality is extreme.
The Political Economy of Transition
Authors: Roland Gérard
Published: October 2002

The overriding importance of political constraints in the transition process has led to developments of the theory of the political economy of reform. What are the main insights from that theory? How does it reflect the transition reality? What have we learned, and what do we still need to learn?

The present article will attempt to answer those questions.
The Great Divide and Beyond: Financial Architecture in Transition
Authors: Berglof Erik , Bolton Patrick
Published: October 2002

The Great Divide in economic and financial development and the convergence in financial architecture among the successful countries raise fundamental questions about how financial development interacts with economic growth. Is it possible to engineer a development takeoff by creating a modern financial architecture from scratch? Or are financial institutions and markets a reflection of underlying conditions in the real sector? Or are both financial development and economic growth driven by some other underlying variables? Is it possible to leapfrog certain stages of financial development or must all countries go through a phase of bank-oriented financial architecture? The experience of the transition economies represents a unique opportunity to shed new light on these issues.
Confronting the Environmental Kuznets Curve
Authors: Dasgupta Susmita , Laplante Benoit , Wang Hua , Wheeler David
Published: October 2002

The environmental Kuznets curve posits an inverted-U relationship between pollution and economic development. Pessimistic critics of empirically estimated curves have argued that their declining portions are illusory, either because they are cross-sectional snapshots that mask a long-run “race to the bottom” in environmental standards, or because industrial societies will continually produce new pollutants as the old ones are controlled. However, recent evidence has fostered an optimistic view by suggesting that the curve is actually flattening and shifting to the left. The driving forces appear to be economic liberalization, clean technology diffusion, and new approaches to pollution regulation in developing countries.
Distinguished Lecture on Economics in Government: The New Economy: Post Mortem or Second Wind?
Authors: Baily Martin Neil
Published: October 2002

There was an acceleration of U.S. productivity after 1995. Investment in information technology hardware and software contributed importantly to this, but was not its sole cause. In part, heavy IT investment, perhaps overinvestment, was the result of the booming economy and cheap capital. Besides IT, the expansion of productive firms boosted productivity, together with the competitive pressure this put on other firms to innovate and improve. Productivity growth has been surprisingly strong in 2001, and the likely trend for the future is in the range of 2.2 to 2.7 percent a year. The economy should get a second wind.
The Economics of Patents: Lessons from Recent U.S. Patent Reform
Authors: Gallini Nancy T
Published: October 2002

U.S. patent reform over the past two decades has strengthened the legal enforcement of patent rights and has extended protection to new subject matter, such as genetically engineered life forms and business methods. This paper highlights these and other policy changes and the debate that this apparent increase in protection has sparked. While the case for stronger patents as a spur to innovation is a weak one, as revealed by recent theoretical and empirical research, evidence that they encourage disclosure and technology transfer is persuasive. The paper discusses the social costs and benefits of these effects from the policy changes and proposals for alleviating the costs through further patent reform.