High resolution observations of friction-induced oxide and its interaction with the worn surface

A detailed transmission electron microscopy study of oxide and oxygen-containing phase formation during the sliding wear of metals, composites and coatings is provided. A wide range of different materials types are reported in order to compare and contrast their oxidational wear behaviour: a low carbon stainless steel, a H21 tool steel containing 7%TiC particles, a 17%Cr white iron,an Al–Si/30%SiC composite, an Al–alloy (6092)–15%Ni3Al composite and finally a 3rd generation TiAlN/CrN ‘superhard’ multilayer coating. For the ferrous alloys, nanoscale oxides and oxygen-containing phases were formed that exhibited excellent adhesion to the substrate. In all cases, an increase in oxide coverage of the surface was associated with a decrease in Lancaster wear coefficient. The oxide at the surface of the 316L and H21+7%TiC was found to deform with the substrate, forming a mechanically mixed layer that enhanced surface wear resistance. Evidence of oxidational wear is presented for the wear of the Al–Si–30%SiC composite, but this did not give a beneficial effect in wear, a result of the brittle nature of the oxide that resulted in detachment of fine (150nm) thick fragments. The worn surface of the Al–alloy (6092)–15%Ni3Al and TiAlN/CrN coating was characterized by reaction with the counterface and subsequent oxidation, the product of which enhanced wear resistance. The observations are related to the classical theory of oxidational wear

VISUALIZATION MODEL FOR PRODUCT LIFECYCLE MANAGEMENT

Product Lifecycle Management (PLM) demonstrated to be a good strategy for manufacturing enterprises. In spite of all the benefits it is not still clear how to implement it in industry. This article presents a visualization model of enterprise processes for a PLM system. It presents in a graphic way the main elements of a product lifecycle. The model identifies what is done (process, activities), when it is done (workflows), who does what (roles - skills) and how it can be done better (methods and tools). UML-RUP is used as representation technique. A case study, which analyzes the specification and inspection procedures of geometric tolerances according to the GPS approach, proves the convenience of this model for supporting PLM implementation

Point-Load Test Assesment as Study of Adobe Buildings Damaged after the 2017 Puebla Earthquake

The 2017 Puebla Earthquake on September 19 struck a big part of Mexico causing the loss of historic buildings in several states, being the state of Morelos one of the most damaged in the whole country. Jojutla de Juarez was the most affected locality of Morelos presenting important structural damages or total collapse in the built heritage, being the traditional earthen buildings, made of adobe bricks, the most vulnerable buildings to seismic efforts. Some of the causes which contributed to the poor behaviour of the buildings were the improper handling of the constructive systems and materials, the insufficient resistance of the structures and the problems derivate by the foundations. The adobe houses of Jojutla presented a mixture between the traditional building techniques and industrial materials like concrete, bricks, blocks and steel; also with irregular heights and plant layouts and inadequate connections between the walls and foundations and roofs, resulting into a higher seismic vulnerability when the earthquake impacted. Also the adobe bricks presented irregularities in its composition and use of additives which resulted in completely different typologies and the loss of the traditional construction techniques. There was conducted a study to determine the earthquake resistance of the adobe bricks of the houses in Jojutla, considering that the remaining structures were severely damaged and a whole study of the seismic vulnerability would not be possible due the loss of the physical buildings. The granulometry and composition of the adobe samples of the buildings were determined as well as the natural aggregates like straw and its proportion. Also the compressive strength of the pieces was tested by two methods: the compression test and the point-load test, in order to obtain the indicative values which could be compared with other patrimonial and vernacular study cases

La troje michoacana, una herencia constructiva purhépecha

La troje michoacana ha sido estudiada desde muchos campos de la arquitectura, como vivienda e ícono cultural, sin embargo, poco se aborda el aspecto constructivo y el diseño de cada elemento que conforma esta edificación. Es común la desaparición paulatina de las trojes michoacanas debido a distintos aspectos: la pérdida del conocimiento constructivo, la escasez de la materia prima para su edificación y los costos ante los materiales contemporáneos, siendo estos aspectos los que afectan en gran medida el patrimonio cultural, poniendo en riesgo toda una tradición constructiva local dejando como vestigio la poca producción arquitectónica de esta tipología que existe hasta el momento. El presente trabajo desglosa los materiales, sistema constructivo y las causas de su deterioro desde el punto de vista físico y mecánico con el objetivo de ampliar los estudios sobre esta tipología arquitectónica y ayudar a la conservación de sus materiales. Esta construcción tiene la peculiaridad de poder ser desarmada y rearmada gracias a su sistema constructivo.Tópico 5: Patrimonios Urbano, Rural, Industrial y Religioso. Cementerios Patrimoniales. Técnicas de Evaluación, Limpieza, Reparación y Conservación. Intervenciones en construcciones con patologías estructurales y aplicación de refuerzos

Electromagnetic Form Factors and Charge Radii of Pseudoscalar and Scalar Mesons: A Comprehensive Contact Interaction Analysis

We carry out a comprehensive survey of electromagnetic form factors of all light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our analysis is based upon a Schwinger-Dyson equations treatment of a vector $\times$ vector contact interaction. It incorporates confinement and ensures axial vector and vector Ward-Takahashi identities are satisfied along with the corresponding corollaries such as the Goldberger-Treiman relations. The algebraic simplicity of the model allows us to compute the form factors at arbitrarily large virtualities of the probing photon momentum squared with relative ease. Wherever possible and insightful, we compare our results for the electromagnetic form factors and the charge radii with those obtained earlier through Schwinger-Dyson equations, lattice and with experimental observations available. We also comment on the scope and shortcomings of the model.Comment: 13 pages, 13 figure