Material concepts for top of rail friction management – Classification, characterisation and application

The concept of managing and adjustment of friction between the wheel and rail has a long history within the operation of railways systems. In the past, adjustment/management has been limited to gauge face lubrication and the use of sanding equipment. The introduction of the top of rail (TOR) friction modifier (FM) over the last 20 years now allows for the modification of the friction at the top of rail–wheel tread interface. This paper focusses on the concept of TOR friction adjustment. Recent developments have led to a new generation of products, defined here as, TOR lubricants (oil and/or grease-based) and hybrid materials (oil/water mixtures), which are non-drying or slow drying. Definitions and functional difference are detailed and contrasted with that of the water-based drying FM. The water-based TOR-FM once applied rapidly dries, mixes with the existing third-body layer, and allows for the accommodation of shear displacement. TOR lubricants and hybrid materials rely on mixed boundary layer lubrication, contrary to application of the water-based TOR-FM. It has been shown that the adhesion level is highly influenced by the lubricant application rates. The risks and benefits (lateral force reduction, corrugation mitigation, and impact on energy consumption and influence on rolling contact fatigue) are discussed for all product classifications. However, a lack of data exists for the TOR lubricants especially in the area of rolling contact fatigue where laboratory studies have identified the possibility of crack interaction. Whilst it can be seen that TOR lubricants have the ability to provide similar benefits to that of a water-based FM, they exhibit a strong dependency on the application rate which may lend itself to adhesion and RCF issues. Further work is recommended in this area

Objective test in economics

73 p.; 19 cm

Yttrium amidate complexes : fundamental reactivity and applications in catalysis and polymerization

Rare-earth complexes are attractive catalyst systems due to their low cost, low toxicity and high reactivity. Modular ligand sets are ideal for complex formation since the steric and electronic properties of the resultant metal complexes can be easily varied. This thesis explores the structure and reactivity of new yttrium amidate complexes, which combine the highly reactive metal with the modular amidate ligand set. A library of tris, bis and mono(amidate) yttrium complexes have been directly synthesized from yttrium tris(trimethylsilyl)amidate and simple amide proligands. The tris(amidate) yttrium complexes are highly active initiators of ring-opening polymerization of Ɛ-caprolactone, yielding some of the largest molecular weight values for poly(Ɛ-caprolactone) reported. The initiation of this polymerization is proposed to be ligand initiated; however, a side-reaction is postulated where formation of a Ɛ-caprolactone-enolate yttrium complex results in broad polydispersity values of the resultant polymers. The bis(amidate) yttrium complexes are also excellent precatalysts for the hydroamination of aminoalkenes. Simple modification to the amidate backbone to include electron-withdrawing groups was found to significantly enhance reaction efficiency. These catalysts can mediate cyclohydroamination with both primary and secondary amine containing substrates. The mono(amidate) yttrium complexes were also investigated as novel precursors for the synthesis of the elusive terminal yttrium imido complex. Mixed anilido/amidate yttrium complexes were synthesized in high yield and a-H abstraction and deprotonation reactions were attempted in the hopes of isolating a crystalline compound. The addition of monodentate and neutral donors was required for isolation and characterization of the key reactive intermediates. This new family of yttrium complexes has proven to be very successful in preliminary catalytic studies. The ease with which the complexes can be synthesized and their steric and electronic properties make these complexes ideal for further catalytic investigations.Science, Faculty ofChemistry, Department ofGraduat

Reclamation fox ungulates in southeastern British Columbia

Only someone who is on site at all times will have the necessary intimate knowledge of an area to decide on the best possible approach to any problem. As these people will be responsible for the eventual reclamation, it is only reasonable that they should make the ultimate decision and interpretation of any recommendations for exploration road construction and reclamation.Non UBCUnreviewedOthe