Twisting, type-N vacuum gravitational fields with symmetries

The Einstein field equations for twisting, type-N fields in empty space possessing two noncommuting Killing vectors are reduced to a single second-order ordinary differential equation for a complex function. Alternative forms of this basic equation are also presented; in particular, an appropriate Legendre transform provides a partial linearization, leading to a single real, nonlinear, third-order ordinary differential equation

New backlund-transformations and superposition principle for gravitational-fields with symmetries

Vector Bäcklund transformations which relate solutions of the vacuum Einstein equations having two commuting Killing fields are introduced. Such transformations generalize those found by Pohlmeyer in connection with the nonlinear δ model. A simple algebraic superposition principle, which permits the combination of Bäcklund transforms in order to get new solutions, is given. The superposition preserves the asymptotic flatness condition, and the whole scheme is manisfestly O(2, 1) invariant

Assessing the potential for vertical urban agriculture for multi-storey buildings

This thesis proposes the use of urban agriculture as a tool to address three global challenges related to population growth in cities; densification, climate change and health risk by studying the history and benefits of urban agriculture, it is possible to understand the benefits in better integrating urban agriculture into new urban infrastructure, particularly in high-density housing areas. These benefits include; better living conditions, reduced food transportation, stormwater management and strong links between communities. The concept of urban agriculture in green infrastructure was tested with a case study of the proposed Törnrosen development in Rosengård, Malmö, to give a specific context to the theory, in which were used global examples of innovative urban agriculture projects for inspiration, alongside details of the current possibilities of urban green infrastructure technology and analysis of the study area and creative design solutions are developed to find out what is possible. The project finds that when green infrastructure is integrated into the Törnrosen tower, additional benefits to the residents and broader a community is likely to increase, if it is adapted to support urban agriculture, and alongside other urban agriculture community projects in the neighbourhood to have a more significant impact on the quality of life in Rosengård. The use of specific urban agriculture infrastructure will depend on location, type of users, the intention of the garden and stakeholders involved in the gardens. The design principals made to design and evaluate the community gardens could be used for other projects with similarities in the future

Stationary axisymmetric SU(2) Einstein-Yang-Mills fields with restricted circularity conditions are Abelian

In this paper we prove that in a stationary axisymmetric SU(2) Einstein-Yang-Mills theory the most reasonable circularity conditions that can be considered for the Yang-Mills fields imply in fact that the field is of embedded Abelian type, or else that the metric is not asymptotically flat

Indirect monitoring method of tool wear using the analysis of cutting force during dry machining of Ti alloys

In recent decades, optimize tool life is in constant evolution so many researchers have focused to analysis the tool wear by indirect monitoring (e.g. acoustic emission, cutting forces, vibrations) that plays a significant role in control and improvement of product during of machining operations - in real time to prevent instabilities of process. On another hand, it is recalled that titanium alloys are used in many industries as aerospace sector that have been utilized in strength to weight ration reduction in some parts of aircraft. On the negative side, Ti alloys tends to be hard machining due to their mechanical properties such as low thermal conductivity and modulus of elasticity causing increase cutting temperature, tool breakage or possibility interruption of process.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Indirect Adhesion Wear Parametric Analysis in the Dry Turning of UNS A97075 Alloys

In this work a study of the influence of cutting parameters (cutting speed, feed and depth of cut) on indirect adhesion tool wear in the dry machining of UNS A97075 Al-Zn alloys has been made. In addition, an experimental methodology for a first approach to the measurement of Built-Up-Layer on the tool has been developed. Finally, different parametric models have been obtained, which allow predicting the BUL evolution as a function of cutting parameters applied.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Use of additive manufacturing on models for sand casting process

Casting is a forming process based on material pouring in liquid state. Heat is applied to melt the material from its solid state and pour it in a mold previously constructed to obtain the desired shape after letting it cool. Molds can be permanent or expendable. In sand casting processes, the mold is manufactured from a model that usually is extracted before pouring the melted material (Figure 1). To obtain the part, the sand model needs to be destroyed. Notwithstanding, the sand can be reused several times for new molds. Several elements are needed to obtain a part by a sand casting process: permanent patterns, flasks (cope and drag), gating system (pouring cup, sprue, risers and feeding channels) and cores (only if it is needed). The aim of this work is the manufacturing of some of these elements by additive manufacturing process. The equipment will be used for the practical activities (Figure 1) that currently take place on the subjects where this topic is taught, in the different Degrees in Industrial Engineering at the University of Malaga.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Fatigue test bench manufacturing by reusing a parallel lathe

Fatigue life of machined parts strongly depends on their surface condition. The rotating bar bending fatigue testing method is widely used to obtain the fatigue behavior of metallic materials due to its simplicity. In this work, the methodology for the design, manufacturing and setup of a fatigue test bench is exposed. The main novelty lies on the reuse of several elements from an old parallel lathe, currently out of order, and their use to manufacture some parts for the test bench. In this way, a double objective is achieved: high quality elements are recycled and the machine manufacturing cost is reduced.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Parametric Analysis of the Ultimate Tensile Strength in Dry Machining of UNS A97075 Alloy

Aluminium alloys (mainly 2XXX and 7XXX series) have been traditionally used in the industry in the manufacture of structural parts in aircrafts, due to their excellent ratio density-mechanical properties. Machining is commonly used in the manufacture of these parts. In addition, the actual trend is machining in dry, due to environmental and economic reasons. Under these conditions, surface integrity becomes one of the most important quality requirements applicable to machined parts. The micro and macro-geometrical properties analysis of the dry machined surface as a function of the cutting parameters is widely studied. Notwithstanding, there is a lack of research in the field dedicated to the physicochemical properties. In this paper the feed influence on the ultimate tensile strength for UNS A97075 (Al-Zn) alloy turned in dry is presented, as a first approximation to the study of the influence of the cutting parameters on this mechanical property.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Emprendimiento como oportunidad de prosperidad bajo una perspectiva de proyección social

EL TRABAJO FINAL DE GRADO QUE SE PRESENTA A CONTINUACIÓN SURGE GRACIAS A LA COLABORACIÓN ENTRE LA CLÍNICA JURÍDICA DE LA UNIVERSIDAD MIGUEL HERNÁNDEZ Y LA ORGANIZACIÓN NO GUBERNAMENTAL ELCHE ACOGE. UN PROYECTO DE COMPROMISO Y DE INTERÉS SOCIAL, QUE NOS PERMITE VIVIR DE PRIMERA MANO UN CONTACTO DIRECTO CON LA PRÁCTICA REAL EN CIERTAS MATERIAS RELACIONADAS CON LA DEFENSA DE COLECTIVOS VULNERABLES, A TRAVÉS DEL DESARROLLO DE UNA GUÍA Y DE SU POSTERIOR PRESENTACIÓN PRESENCIAL. EN LA ACTUALIDAD, ALGUNOS COLECTIVOS DESFAVORECIDOS SUFREN EXCLUSIÓN SOCIAL Y/O RIESGO DE POBREZA, NUESTRO OBJETIVO ES PODER COLABORAR EN SU PROGRESIVA DISMINUCIÓN O DESAPARICIÓN, CONTRIBUYENDO, PARA PODER CONSTRUIR ASÍ, UNA SOCIEDAD MEJOR, MÁS IGUALITARIA Y JUSTA. LA GUÍA CONTENDRÁ LOS ASPECTOS MÁS RELEVANTES SOBRE LA CREACIÓN DE NEGOCIOS, SIENDO ASÍ UNA AYUDA QUE MOTIVE EL EMPRENDIMIENTO Y FACILITE ASÍ UNA SALIDA LABORAL A ESTOS COLECTIVOS, EN ESPECIAL, A LA POBLACIÓN EXTRANJERA, QUE ES LA MÁS PERJUDICADA, EN TÉRMINOS DE POBREZA Y EXCLUSIÓN SOCIAL