Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

INSTRUMENTED START BLOCKS: A QUANTITATIVE COACHING AID

To effect improvement in a skill such as the block start in sprinting, immediate quantitative feedback pertaining to the forces generated during the start is invaluable to both the coach and athlete. The purpose of the present study was to design a set of instrumented starting blocks, appropriate for use in the field, which would provide immediate feedback pertaining to the kinetics of a block start. Design considerations included: resolution of orthogonal force components for right and left foot pedals independently; adjustability to enable and athlete's normal foot and block placement; and adhering to standard international starting block design specifications in terms of dimensions and rigidity. The starting blocks consisted of two standard adjustable stadium starting block pedals suspended clear of the ground via two instrumented axles. The mild steel rod axles were milled to dimensions which allowed the axles to deflect minimally under expected loads. Each axle was attached laterally (and directed medially) from a 230 mm wide mild steel parallel flange channel. This base plate was firmly affixed to the synthetic track surface by six 12 mm commercial shoe spikes. Eight 3 mm student strain gauges were adhered to each axle with 4 gauges aligned to each orthogonal axis. The gauges were incorporated into a Wheatstone Bridge circuitry and arranged to measure the shear force on the axle by utilising the bending moment difference method. Using this bending moment difference method, the magnitude of the force signal recorded was unaffected by the position of force application across the block pedal. Each of the 4 orthogonal channels contained a separate amplifier to magnify the differential signal from the gauges. Calibration was accomplished via static loading of each axle in the orthogonal plane with known loads. The differential signal developed from the strain gauge circuitry under load was amplified and sampled (1000 Hz) by a personal computer using a WIN 30-D A-D converter card. From this data useful variables such as maximum horizontal and vertical force, impulse, block time, block velocity and block acceleration were quantified using custom software and were immediately available to the athlete and coach. Analysis of data obtained from the blocks for state level, national level and the current male 100 m world champion indicated the instrumented blocks were able to provide immediate relevant kinetic data for use by sprint coaches in the field

Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

Minimal Position-Velocity Uncertainty Wave Packets in Relativistic and Non-relativistic Quantum Mechanics

We consider wave packets of free particles with a general energy-momentum dispersion relation $E(p)$. The spreading of the wave packet is determined by the velocity v = \p_p E. The position-velocity uncertainty relation $\Delta x \Delta v \geq {1/2} ||$ is saturated by minimal uncertainty wave packets $\Phi(p) = A \exp(- \alpha E(p) + \beta p)$. In addition to the standard minimal Gaussian wave packets corresponding to the non-relativistic dispersion relation $E(p) = p^2/2m$, analytic calculations are presented for the spreading of wave packets with minimal position-velocity uncertainty product for the lattice dispersion relation $E(p) = - \cos(p a)/m a^2$ as well as for the relativistic dispersion relation $E(p) = \sqrt{p^2 + m^2}$. The boost properties of moving relativistic wave packets as well as the propagation of wave packets in an expanding Universe are also discussed

An adaptive inelastic magnetic mirror for Bose-Einstein condensates

We report the reflection and focussing of a Bose-Einstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beam-expander, producing an ultra-cold collimated fountain of matter wavesComment: 4 pages, 4 figure

Testing quantum correlations in a confined atomic cloud by scattering fast atoms

We suggest measuring one-particle density matrix of a trapped ultracold atomic cloud by scattering fast atoms in a pure momentum state off the cloud. The lowest-order probability of the inelastic process, resulting in a pair of outcoming fast atoms for each incoming one, turns out to be given by a Fourier transform of the density matrix. Accordingly, important information about quantum correlations can be deduced directly from the differential scattering cross-section. A possible design of the atomic detector is also discussed.Comment: 5 RevTex pages, no figures, submitted to PR

Temperature Variation of Ultra Slow Light in a Cold Gas

A model is developed to explain the temperature dependence of the group velocity as observed in the experiments of Hau et al (Nature {\bf397}, 594 (1999)). The group velocity is quite sensitive to the change in the spatial density. The inhomogeneity in the density and its temperature dependence are primarily responsible for the observed behavior.Comment: 12 pages, 4 figure

On the stability of standing matter waves in a trap

We discuss excited Bose-condensed states and find the criterion of dynamical stability of a kink-wise state, i.e., a standing matter wave with one nodal plane perpendicular to the axis of a cylindrical trap. The dynamical stability requires a strong radial confinement corresponding to the radial frequency larger than the mean-field interparticle interaction. We address the question of thermodynamic instability related to the presence of excitations with negative energy.Comment: 4 pages, 3 figure

Effect of anharmonicities in the critical number of trapped condensed atoms with attractive two-body interaction

We determine the quantitative effect, in the maximum number of particles and other static observables, due to small anharmonic terms added to the confining potential of an atomic condensed system with negative two-body interaction. As an example of how a cubic or quartic anharmonic term can affect the maximum number of particles, we consider the trap parameters and the results given by Roberts et al. [Phys. Rev. Lett. 86, 4211 (2001)]. However, this study can be easily transferred to other trap geometries to estimate anharmonic effects.Comment: Total of 5 pages, 3 figures and 1 table. To appear in Phys. Rev.

Barrier effects on the collective excitations of split Bose-Einstein condensates

We investigate the collective excitations of a single-species Bose gas at T=0 in a harmonic trap where the confinement undergoes some splitting along one spatial direction. We mostly consider onedimensional potentials consisting of two harmonic wells separated a distance 2 z_0, since they essentially contain all the barrier effects that one may visualize in the 3D situation. We find, within a hydrodynamic approximation, that regardless the dimensionality of the system, pairs of levels in the excitation spectrum, corresponding to neighbouring even and odd excitations, merge together as one increases the barrier height up to the current value of the chemical potential. The excitation spectra computed in the hydrodynamical or Thomas-Fermi limit are compared with the results of exactly solving the time-dependent Gross-Pitaevskii equation. We analyze as well the characteristics of the spatial pattern of excitations of threedimensional boson systems according to the amount of splitting of the condensate.Comment: RevTeX, 12 pages, 13 ps figure