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The author proposed a friction plunge micro-welding (FPMW) method and applied it to column grid array packaging to realize the connection of copper columns without precision molds assisted positioning. The purpose of this paper is to study the flow behavior of the solder undergoing frictional thermo-mechanical action during the FPMW and to determine the source of the solders in the micro-zones with different microstructure characteristics near the solder/Cu column friction interface.

Three kinds of Sn58Bi/SAC305 and SAC305/Pb90Sn composite solder samples were designed to study the flow behavior of the solder during FPMW using Bi and Pb as tracer elements.

The results show that most of the solders in the position occupied by the copper column was softened and plasticized during the welding process and was extruded to side of the copper column, flowing axially, circumferentially and radially along a trajectory similar to a conical spiral line. Under the drive of the tangential friction force and the radial hold-tight force, the extruded out visco-plastic solders fully mixed with the visco-plastic solders on the sides of the copper column, and bonded with the solders that deformed plastically on the periphery, so that a stir zone and a dynamic recrystallization zone finally evolved. The outside plastically deformed solders evolved into a thermo-mechanical affected zone.

The flow behavior of the solder during the FPMW was determined, as well as the source of the solders in micro-zones with different microstructure characteristics.

The numerical investigation into the stirring induced by an alternating magnetic field, applied in the axial direction of a closed axisymmetric container of conducting fluid, is presented. The interaction between the azimuthal current and magnetic field results in Lorentz forces in the meridional plane which induce the fluid flow. The magnetic Reynolds number is assumed to be smaller than the frequency magnetic Reynolds number. The electromagnetic equations are thus decoupled from the fluid flow equations. The electromagnetic field is first solved, and the body forces determined from this are introduced into the Navier‐Stokes equations. With the flow field known, the quality of mixing is determined by solving the tracer dispersion equation. The finite element method based on a Galerkin formulation is used for the solution of the equations. Three cases are examined: a finite length cylinder, a finite length cylinder with rounded corners and a sphere. In general, two vortices are formed, the equatorial vortex closest to the equator and the end vortex at the closed end. Results show that the introduction of the rounded corner increases the size and strength of the end vortex with the opposite effect on the equatorial vortex. Of the three frequency magnetic Reynolds numbers considered (Rw=30, 100 and 800), Rw=100 results in the best mixing for all cases. Rounding the corner of the cylinder only results in a definite improvement of mixing at Rw=800. The sphere results in even better mixing than this at Rw=800, but is worse than the first two geometries for Rw=30 and 100 when the interaction parameter is large.

This paper aims to investigate the wear behaviour of different materials for cylinder liners and piston rings in a linear reciprocating tribometer with special focus on the wear of the cylinder liner in the boundary lubrication regime.

Conventional nitrided steel, as well as diamond-like carbon and chromium nitride-coated piston rings, were tested against cast iron, AlSi and Fe-coated AlSi cylinder liners. The experiments were carried out with samples produced from original engine parts to have the original surface topography available. Radioactive tracer isotopes were used to measure cylinder liner wear continuously, enabling separation of running-in and steady-state wear.

A ranking of the material pairings with respect to wear behaviour of the cylinder liner was found. Post-test inspection of the cylinder samples by scanning electron microscopy (SEM) revealed differences in the wear mechanisms for the different material combinations. The results show that the running-in and steady-state wear of the liners can be reduced by choosing the appropriate material for the piston ring.

The use of original engine parts in a closely controlled tribometer environment under realistic loading conditions, in conjunction with continuous and highly sensitive wear measurement methods and a detailed SEM analysis of the wear mechanisms, forms an intermediate step between engine testing and laboratory environment testing.

The work on friction in high vacuum was started some years ago in Dr. F. P. Bowdens laboratory in Cambridge University, using an apparatus designed by the late Dr. J. E. Young. The object has been to examine the frictional behaviour of surfaces covered with known films, undisturbed by the contamination always present in a normal atmosphere. A general account of the work was given in Dr. Howe's paper at the Conference on Lubrication and Wear (1957) entitled “Vapour Lubrication and the Friction of Clean Surfaces”. Dr. Rowe was educated at Culford School and Emmanuel College, Cambridge, where he took Mechanical Sciences Tripos in 1944 and Natural Science Tripos Part II (Physics) in 1950. He wrote a thesis on “Adhesion of Clean Metals” in Dr. Bowden's laboratory at Cambridge in 1953. From 1944–46 he was engaged on miniaturisation at the Telecommunications Research Establishment and for the next two years was at the Atomic Energy Research Establishment working on cyclotron design. He currently leads a small group interested in friction, lubrication and wear, at Tube Investments Research Laboratories, Cambridge. He is a member of the Institution of Electrical Engineers and the Gesellschaft Deutscher Chemiker.

The monitoring of respirable particulate matter (PM₁₀) and of total carbon percentage (mass basis) in the atmosphere of São Carlos (SP) was performed in the period between September 1997 and January 2000. São Carlos, located in the central region of the state of São Paulo, has a population of close to 180,000 inhabitants and about 500 industrial establishments of medium to small size, mainly dealing with metallurgy, textiles, food and ceramics. The equipment used for air monitoring was a high volume sampler (GVS‐GRASEBY/GMW) equipped with a one‐stage inertial separator for a 10μm particle cut diameter. The PM₁₀ concentration was determined by gravimetry and the total carbon concentration by the Ströheim method. The results show a well defined seasonal dependence of both the PM₁₀ and of the total carbon concentration. Higher concentrations of PM₁₀ and carbon were observed in autumn and winter, which also coincided with low relative humidity and precipitation. The measured trends were compared with the PM₁₀ data from the city of São Paulo in the same period and showed similar seasonal dependence. However, in relative terms, the PM₁₀ concentration in São Carlos showed stronger seasonal dependence than in São Paulo.

Memories and musings of the long ago reveal revolutionary changes in the world's food trade and in particular, food sources and marketing in the United Kingdom. Earliest memories of the retail food trade are of many small shops; it used to be said that, given a good site, food would always sell well. There were multiples, but none of their stores differed from the pattern and some of the firms — Upton's, the International, were household names as they are now. Others, eg., the Maypole, and names that are lost to memory, have been absorbed in the many mergers of more recent times. Food production has changed even more dramatically; countries once major sources and massive exporters, have now become equally massive importers and completely new sources of food have developed. It all reflects the political changes, resulting from two World Wars, just as the British market reflects the shifts in world production.

AMONG new problems faced by design engineers of supersonic aircraft and missiles is the destructive effect of rain. At transonic and supersonic speeds, rain erosion of aircraft materials may prove to be a limiting factor in all‐weather flying conditions.

Perhaps the most surprising thing about educational programmes on the BBC is the sheer number and variety of them. In a typical week ‘in term’ some 40 hours of air time is devoted to what might be called formal educational broadcasting for schools and adults, on radio and television. Ever since the early days of radio the BBC has recognised its obligation to make a systematic contribution to education, and over the years a framework of consultation and advice has built up. The School Broadcasting Council and the Further Education Advisory Council are there to provide continuing links with the world of education: they are the source from which our educational broadcasting springs.

A least‐squares finite element analysis of viscous fluid flow together with a trajectory integration technique for tracers is formulated and provides a mechanism for investigating mixing. Tracer integration is carried out using an improved Heun predictor‐corrector. Results from our supporting numerical studies on the CRAY and Connection Machine (CM) closely resemble the patterns of mixing observed in experiments. A “box‐counting” scheme and other measures to characterize the level of mixing are developed and investigated. This measure is utilized in numerical experiments to determine an optimal forcing frequency for mixing by periodic boundary motion in a rectangular enclosure. Some details concerning the numerical schemes and vector‐parallel implementation are also included.