Fibers and global geometry of functions

Since the seminal work of Ambrosetti and Prodi, the study of global folds was enriched by geometric concepts and extensions accomodating new examples. We present the advantages of considering fibers, a construction dating to Berger and Podolak's view of the original theorem. A description of folds in terms of properties of fibers gives new perspective to the usual hypotheses in the subject. The text is intended as a guide, outlining arguments and stating results which will be detailed elsewhere

Hydrogen entry into pipeline steel under freely corroding conditions in two corroding media

Hydrogen permeation through API 5L X65 pipeline steel was studied under freely corroding conditions in NACE solution (simulated seawater) and poisoned 1 N H2SO4. A steady state condition with regards to permeation flux is not obtained due to the presence of corrosion product, changing sample dimension and a possible change in hydrogen availability on the corroding surface. A unique way of calculating the sub-surface hydrogen concentration (C0) under non-steady state freely corroding conditions has been developed. The C0 has been evaluated as a function of exposure time in NACE solution and poisoned H2SO4 solution. The sub-surface hydrogen concentration (C0) increased initially but then decreased with increasing exposure to the corroding solutions, after demonstrating an early maximum. The changes in C0 have been explained taking into consideration the corrosion products that developed, the possible anodic reactions, the changes in sample thickness and other issues in the dynamic system

Study of Hydrogen Permeation Behaviour of High Strength Aluminium Alloys

Aluminum, with its multifaceted wonders has amazed and attracted peoples to use i t in variety of applications. Aluminium offers a wide range of properties that can be engineered to the demands of specific applicaions through the choice of alloy, temper and fabrication process

Electrochemical response of amorphous and devitrified Al-Ni-La-X (X = Ag, Cu) alloys

The electrochemical response of melt-spun Al-Ni-La alloys with partial substitution of Ni after different stages of devitrification was studied. The base alloy was found to have the best corrosion resistance. It was observed that primary crystallization caused minimal deterioration in the corrosion resistance of the base alloy as compared to its amorphous state. The substitute alloys had different corrosion resistance dependent on the substituting element with the Ag containing alloy having the least resistance. This could be attributed to the operation of local galvanic cells, enhanced by chemical heterogeneities in the alloys. Secondary crystallization caused a reduction in the corrosion resistance of all the alloys due to the creation of intermetallic phases that increased the galvanic activity