Bonded structures for enhanced damage tolerant pressurized fuselages

Adhesive bonding provides solutions to realize cost effective and low weight aircraft fuselage structures, in particular where the Damage Tolerance (DT) is the design criterion. Bonded structures that combine Metal Laminates (MLs) and eventually Selective Reinforcements can guarantee slow crack propagation, crack arrest and large damage capability. To optimize the design exploiting the benefit of bonded structures incorporating selective reinforcement requires reliable analysis tools. The effect of bonded doublers / selective reinforcements is very difficult to be predicted numerically or analytically due to the complexity of the underlying mechanisms and failures modes acting. Reliable predictions of crack growth and residual strength can only be based on sound empirical and phenomenological considerations strictly related to the specific structural concept. Large flat stiffened panels that combine MLs and selective reinforcements have been tested with the purpose of investigating solutions applicable to pressurized fuselages. The large test campaign (for a total of 35 stiffened panels) has quantitatively investigated the role of the different metallic skin concepts (monolithic vs. MLs) of the aluminum, titanium and glass-fiber reinforcements, of the stringers material and cross sections and of the geometry and location of doublers / selective reinforcements. Bonded doublers and selective reinforcements confirmed to be outstanding tools to improve the DT properties of structural elements with a minor weight increase. However the choice of proper materials for the skin and the stringers must be not underestimated since they play an important role as well. A fuselage structural concept has been developed to exploit the benefit of a metal laminate design concept in terms of high Fatigue and Damage Tolerance (F&DT) performances. The structure used laminated skin (0.8mm thick), bonded stringers, two different splicing solutions and selective reinforcements (glass prepreg embedded in the laminate) under the circumferential frames. To validate the design concept a curved panel was manufactured and tested under loading conditions representative of a single aisle fuselage: cyclic internal pressurization plus longitudinal loads. The geometry of the panel, design and loading conditions were tailored for the requirements of the upper front fuselage. The curved panel has been fatigue tested for 60 000 cycles before the introduction of artificial damages (cracks in longitudinal and circumferential directions). The crack growth of the artificial damages has been investigated for about 85 000 cycles. At the end a residual strength test has been performed with a “2 bay over broken frame” longitudinal crack. The reparability of this innovative concept has been taken into account during design and demonstrated with the use of an external riveted repair. The F&DT curved panel test has confirmed that a long fatigue life and high damage tolerance can be achieved with a hybrid metal laminate low weight configuration. The superior fatigue life from metal laminates and the high damage tolerance characteristics provided by integrated selective reinforcements are the key concepts that provided the excellent performances. The weight comparison between the innovative bonded concept and a conventional monolithic riveted design solution showed a significant potential weight saving but the weight advantages shall be traded off with the additional costs.

Pyrochlore der Pegmatit-Provinz Nazareno, Brasilien

Zusammenfassung:Mit Hilfe einer neuen Formel für die Minerale der Pyrochlor-Gruppe werden sämtliche Endglieder der Na-Ca-Mikrolithe und der Ba-haltigen Mikrolithe aus der Pegmatit-Provinz Nazareno beschrieben: Die Na-reichsten Proben haben nahezu die Idealzusammensetzung eines idealen Pyrochlors, d.h. . Die Ca-reichsten Varietäten weisen maximal auf, wobei der Besetzungsanteil des Ca am A2+ ca. 93% beträgt. Die Ba-haltigen Mikrolithe sind durch eine Defektstruktur gekennzeichnet, wobei für das mögliche Endglied kein Beispiel in den Daten vorliegt. Das Endglied mit dem geringsten Defektcharakter hat folgende Stöchiometrie:

Evolution of the structural and fracture design of the ISS payloads due to the new launchers, specifically applied to Biolab IEC-2 projects

The relatively young discipline of astronautics represents one of the scientifically most fascinating and technologically advanced achievements of our time. The human exploration in space does not offer only extraordinary research possibilities but also demands high requirements from man and technology. The space environment provides a lot of attractive experimental tools towards the understanding of fundamental mechanism in natural sciences. It has been shown that especially reduced gravity and elevated radiation, two distinctive factors in space, influence the behavior of biological systems significantly. For this reason one of the key objectives on board of an earth orbiting laboratory is the research in the field of life sciences, covering the broad range from botany, human physiology and crew health up to biotechnology. The Columbus Module is the only European low gravity platform that allows researchers to perform ambitious experiments in a continuous time frame up to several months. Biolab is part of the initial outfitting of the Columbus Laboratory; it is a multi-user facility supporting research in the field of biology, e.g. effect of microgravity and space radiation on cell cultures, micro-organisms, small plants and small invertebrates. The Biolab IEC are projects designed to work in the automatic part of Biolab. In this moment in the TO-53 department of Airbus Defence & Space (formerly Astrium) there are two experiments that are in phase C/D of the development and they are the subject of this thesis: CELLRAD and CYTOSKELETON. They will be launched in soft configuration, that means packed inside a block of foam that has the task to reduce the launch loads on the payload. Until 10 years ago the payloads which were launched in soft configuration were supposed to be structural safe by themselves and a specific structural analysis could be waived on them; with the opening of the launchers market to private companies (that are not under the direct control of the international space agencies), the requirements on the verifications of payloads are changed and they have become much more conservative. In 2012 a new random environment has been introduced due to the new Space-X launch specification that results to be particularly challenging for the soft launched payloads. The last ESA specification requires to perform structural analysis on the payload for combined loads (random vibration, quasi-steady acceleration and pressure). The aim of this thesis is to create FEM models able to reproduce the launch configuration and to verify that all the margins of safety are positive and to show how they change because of the new Space-X random environment. In case the results are negative, improved design solution are implemented. Based on the FEM result a study of the joins has been carried out and, when needed, a crack growth analysis has been performed.

Measurement of LSP-induced residual stresses and fatigue life on thin-walled aluminium alloys specimens

This thesis work encloses activities carried out in the Laser Center of the Polytechnic University of Madrid and the laboratories of the University of Bologna in Forlì. This thesis focuses on the superficial mechanical treatment for metallic materials called Laser Shock Peening (LSP). This process is a surface enhancement treatment which induces a significant layer of beneficial compressive residual stresses underneath the surface of metal components in order to improve the detrimental effects of the crack growth behavior rate in it. The innovation aspect of this work is the LSP application to specimens with extremely low thickness. In particular, after a bibliographic study and comparison with the main treatments used for the same purposes, this work analyzes the physics of the operation of a laser, its interaction with the surface of the material and the generation of the surface residual stresses which are fundamentals to obtain the LSP benefits. In particular this thesis work regards the application of this treatment to some Al2024-T351 specimens with low thickness. Among the improvements that can be obtained performing this operation, the most important in the aeronautic field is the fatigue life improvement of the treated components. As demonstrated in this work, a well-done LSP treatment can slow down the progress of the defects in the material that could lead to sudden failure of the structure. A part of this thesis is the simulation of this phenomenon using the program AFGROW, with which have been analyzed different geometric configurations of the treatment, verifying which was better for large panels of typical aeronautical interest. The core of the LSP process are the residual stresses that are induced on the material by the interaction with the laser light, these can be simulated with the finite elements but it is essential to verify and measure them experimentally. In the thesis are introduced the main methods for the detection of those stresses, they can be mechanical or by diffraction. In particular, will be described the principles and the detailed realization method of the Hole Drilling measure and an introduction of the X-ray Diffraction; then will be presented the results I obtained with both techniques. In addition to these two measurement techniques will also be introduced Neutron Diffraction method. The last part refers to the experimental tests of the fatigue life of the specimens, with a detailed description of the apparatus and the procedure used from the initial specimen preparation to the fatigue test with the press. Then the obtained results are exposed and discussed.

The adaptive power of the present: Perceptions of past, present, and future life satisfaction across the life span

Despite remarkable stability of life satisfaction across the life span, it may be adaptive to perceive change in life satisfaction. We shed new light on this topic with data from 766 individuals from three age groups and past, present, and future life satisfaction perceptions across the life span. On average, participants were most satisfied with their current life. When looking back, satisfaction increased from past to present, and when looking ahead, satisfaction decreased into the future. Trajectories were best fitted with a curvilinear growth model. Neuroticism and extraversion predicted the level of trajectories, but none of the Big Five predicted the slope. We conclude that humans have an adaptive capacity to perceive the present life as being the best possible.

Analyzing diffuse scattering with supercomputers

Two new approaches to quantitatively analyze diffuse diffraction intensities from faulted layer stacking are reported. The parameters of a probability-based growth model are determined with two iterative global optimization methods: a genetic algorithm (GA) and particle swarm optimization (PSO). The results are compared with those from a third global optimization method, a differential evolution (DE) algorithm [Storn & Price (1997). J. Global Optim. 11, 341–359]. The algorithm efficiencies in the early and late stages of iteration are compared. The accuracy of the optimized parameters improves with increasing size of the simulated crystal volume. The wall clock time for computing quite large crystal volumes can be kept within reasonable limits by the parallel calculation of many crystals (clones) generated for each model parameter set on a super- or grid computer. The faulted layer stacking in single crystals of trigonal three-pointedstar- shaped tris(bicylco[2.1.1]hexeno)benzene molecules serves as an example for the numerical computations. Based on numerical values of seven model parameters (reference parameters), nearly noise-free reference intensities of 14 diffuse streaks were simulated from 1280 clones, each consisting of 96 000 layers (reference crystal). The parameters derived from the reference intensities with GA, PSO and DE were compared with the original reference parameters as a function of the simulated total crystal volume. The statistical distribution of structural motifs in the simulated crystals is in good agreement with that in the reference crystal. The results found with the growth model for layer stacking disorder are applicable to other disorder types and modeling techniques, Monte Carlo in particular.

Germania: l’indomabile trading state

Basato su interviste con i principali attori tedeschi e su un’analisi della letteratura, l’articolo analizza lo sviluppo recente dell’economia tedesca e la strategia tedesca nell’affrontare la crisi dell’eurozona. La Germania è uno stato commerciale (trading state), la cui crescita è fortemente trainata dalle esportazioni. Fino agli anni novanta, rigidità istituzionali forti, nel sistema di relazioni industriali e nel sistema di protezione sociale, contribuivano a conciliare lo sviluppo delle esportazioni con una crescita armonica dei consumi interni, contribuendo cosi a ingabbiare la «tigre» tedesca. A partire dagli anni novanta, sia le relazioni industriali sia la protezione sociale sono state fortemente liberalizzate, stimolando ulteriormente la competitività estera e indebolendo i consumi interni. Il modello economico tedesco, cosi come è venuto profilandosi negli ultimi dieci anni, è alla base delle politiche di austerità che la Germania impone all’Europa. Tali politiche sono fortemente condivise dai partiti politici, dagli attori sociali e dall’opinione pubblica, e le probabilità che la strategia tedesca cambi sono minime.

The Crisis and Germany: The Trading State Unleashed

Based on interviews with the main German actors and on secondary sources, the article examines the recent development of the German political economy, and the German strategy vis-à-vis the Euro zone. Germany is a trading state whose economic growth is strongly export-led. Until the years 1990s, strong institutional rigidities, both in industrial relations and in the welfare state, contributed to reconcile export growth with household consumption, thus keeping the German “tiger” on a leash. From the early 1990s on, however, both industrial relations and social protections have been strongly liberalized, thus further stimulating external competitiveness and reducing the role of consumption in the German growth model. The unleashed trading state shapes the German response to the Euro crisis and the austerity policies that Germany imposes to Europe. These policies are strongly supported by political parties, social actors, and public opinion in Germany, and the likelihood that they change in the near future is minimal.

A Single-blinded, Randomized Clinical Trial of How to Implement an Evidence-based Treatment for Generalized Anxiety Disorder [IMPLEMENT] — Effects of Three Different Strategies of Implementation

BACKGROUND: Despite long-standing calls to disseminate evidence-based treatments for generalized anxiety (GAD), modest progress has been made in the study of how such treatments should be implemented. The primary objective of this study was to test three competing strategies on how to implement a cognitive behavioral treatment (CBT) for out-patients with GAD (i.e., comparison of one compensation vs. two capitalization models). METHODS: For our three-arm, single-blinded, randomized controlled trial (implementation of CBT for GAD [IMPLEMENT]), we recruited adults with GAD using advertisements in high-circulation newspapers to participate in a 14-session cognitive behavioral treatment (Mastery of your Anxiety and Worry, MAW-packet). We randomly assigned eligible patients using a full randomization procedure (1:1:1) to three different conditions of implementation: adherence priming (compensation model), which had a systematized focus on patients' individual GAD symptoms and how to compensate for these symptoms within the MAW-packet, and resource priming and supportive resource priming (capitalization model), which had systematized focuses on patients' strengths and abilities and how these strengths can be capitalized within the same packet. In the intention-to-treat population an outcome composite of primary and secondary symptoms-related self-report questionnaires was analyzed based on a hierarchical linear growth model from intake to 6-month follow-up assessment. This trial is registered at ClinicalTrials.gov (identifier: NCT02039193) and is closed to new participants. FINDINGS: From June 2012 to Nov. 2014, from 411 participants that were screened, 57 eligible participants were recruited and randomly assigned to three conditions. Forty-nine patients (86%) provided outcome data at post-assessment (14% dropout rate). All three conditions showed a highly significant reduction of symptoms over time. However, compared with the adherence priming condition, both resource priming conditions indicated faster symptom reduction. The observer ratings of a sub-sample of recorded videos (n = 100) showed that the therapists in the resource priming conditions conducted more strength-oriented interventions in comparison with the adherence priming condition. No patients died or attempted suicide. INTERPRETATION: To our knowledge, this is the first trial that focuses on capitalization and compensation models during the implementation of one prescriptive treatment packet for GAD. We have shown that GAD related symptoms were significantly faster reduced by the resource priming conditions, although the limitations of our study included a well-educated population. If replicated, our results suggest that therapists who implement a mental health treatment for GAD might profit from a systematized focus on capitalization models. FUNDING: Swiss Science National Foundation (SNSF-Nr. PZ00P1_136937/1) awarded to CF. KEYWORDS: Cognitive behavioral therapy; Evidence-based treatment; Implementation strategies; Randomized controlled trial

Respuesta fotoperiódica en Origanum vulgare ssp. vulgare y ssp. hirtum Ietsw. : impacto sobre su desarrollo y crecimiento

La productividad del orégano (Origanum vulgare L.) está determinada por la conjunción entre cantidad de biomasa acumulada y contenido de aceite esencial hasta el momento de su cosecha. Numerosos autores han constatado que dicho contenido es máximo al momento de floración pero los procesos que determinan la ocurrencia de la misma son poco claros en esta especie. A través de la prolongación artificial del fotoperíodo, se evaluó la sensibilidad fotoperiódica de dos subespecies tradicionales de orégano (Compacto: Origanum vulgare ssp. vulgare y Criollo: Origanum vulgare ssp. hirtum Ietsw.) y su incidencia en el desarrollo, duración de fases fenológicas y en la dinámica de crecimiento. Se encontró que ambas responden al aumento del fotoperíodo reduciendo la longitud de su ciclo. Ante estas condiciones, las mismas difirieron en la magnitud de su respuesta, siendo la subespecie Criollo más sensible que Compacto. Esto sugiere que el umbral fotoperiódico de inducción a floración es menor en el orégano Criollo que en el orégano Compacto. El acortamiento de la fase de desarrollo vegetativo en ambas subespecies generó menor número de nudos y longitud de ramas finales (disminución más notoria en la subespecie Criollo). El fotoperíodo extendido generó un cambio en el modelo de crecimiento de la longitud de ramas de lineal a lineal con meseta o cuadrático.

Back to the future to revisit meanings

Tanto en los estudios sincrónicos como en los diacrónicos queda en evidencia que el español posee diferentes formas de expresar el tiempo futuro. Por ejemplo, la desinencia del futuro morfológico (-ré) alterna en el español actual con la perífrasis verbal ir+a+infinitivo tal y como se ve en los siguientes ejemplos de la variedad rioplatense: (1) CFK advirtió que "Vamos a sostener este modelo de crecimiento con todas las decisiones que haya que tomar" (Diario Digital 25-04-2012); (2) Rossi aseguró que votarán a favor de YPF unos doscientos diputados (La Nación 28-04-2012). Este hecho ha sido analizado por innumerables estudios y autores, muchos de los cuales se han aproximado a este tema desde la perspectiva variacionista que relaciona significados y contextos (Martínez 1987, Sedano 1994, Company 1999, Alaniz 2010); esta perspectiva explica dicha alternancia por medio de un continuum de factualidad el cual va desde la mayor factualidad de la perífrasis a la menor factualidad de la forma sintética. El análisis de los datos de acuerdo con dichos significados básicos postulados parecía confirmar la hipótesis, al menos en los contextos relacionados con la comunicación oral cotidiana (Martínez 1987). Sin embargo, un estudio más profundo sobre los usos de dichas formas en otros géneros discursivos (Mailhes 2010) nos lleva a replantearnos los significados básicos. En este sentido, la hipótesis que nos interesa confirmar es que las formas se encuentran vinculadas a la evaluación de los hechos por medio de la posibilidad de ejercer control sobre los mismos . Si existe control, se puede seleccionar la perífrasis; si no existe, la forma sintética será más apropiada. La ausencia de control puede dar lugar a una posibilidad más o menos remota así como a la profecía, dos esferas donde la variación es explotada

Balance del modelo agroexportador en América Latina al comenzar el siglo XXI

El propósito de este escrito es ofrecer un panorama del momento por el que atraviesa hoy la agricultura regional, revisando algunos de sus saldos agregados. Nos interesa debatir el tono optimista y acrítico con que se divulgan las cifras y poner en evidencia aspectos menos difundidos, pero de suma importancia para el presente y futuro de la región. Para comenzar nos referimos al contexto general en que se suscitan las transformaciones en el modelo de crecimiento de la región y sus pretensiones. Enseguida nos ocupamos de la agricultura, enfocados en el contenido común de los proyectos nacionales, para revisar luego algunas de sus secuelas. Concluimos con algunas reflexiones sobre el significado de estos cambios para la expansión del capital en tanto sistema y para la población rural involucrada.

Balance del modelo agroexportador en América Latina al comenzar el siglo XXI

El propósito de este escrito es ofrecer un panorama del momento por el que atraviesa hoy la agricultura regional, revisando algunos de sus saldos agregados. Nos interesa debatir el tono optimista y acrítico con que se divulgan las cifras y poner en evidencia aspectos menos difundidos, pero de suma importancia para el presente y futuro de la región. Para comenzar nos referimos al contexto general en que se suscitan las transformaciones en el modelo de crecimiento de la región y sus pretensiones. Enseguida nos ocupamos de la agricultura, enfocados en el contenido común de los proyectos nacionales, para revisar luego algunas de sus secuelas. Concluimos con algunas reflexiones sobre el significado de estos cambios para la expansión del capital en tanto sistema y para la población rural involucrada.

Back to the future to revisit meanings

Tanto en los estudios sincrónicos como en los diacrónicos queda en evidencia que el español posee diferentes formas de expresar el tiempo futuro. Por ejemplo, la desinencia del futuro morfológico (-ré) alterna en el español actual con la perífrasis verbal ir+a+infinitivo tal y como se ve en los siguientes ejemplos de la variedad rioplatense: (1) CFK advirtió que "Vamos a sostener este modelo de crecimiento con todas las decisiones que haya que tomar" (Diario Digital 25-04-2012); (2) Rossi aseguró que votarán a favor de YPF unos doscientos diputados (La Nación 28-04-2012). Este hecho ha sido analizado por innumerables estudios y autores, muchos de los cuales se han aproximado a este tema desde la perspectiva variacionista que relaciona significados y contextos (Martínez 1987, Sedano 1994, Company 1999, Alaniz 2010); esta perspectiva explica dicha alternancia por medio de un continuum de factualidad el cual va desde la mayor factualidad de la perífrasis a la menor factualidad de la forma sintética. El análisis de los datos de acuerdo con dichos significados básicos postulados parecía confirmar la hipótesis, al menos en los contextos relacionados con la comunicación oral cotidiana (Martínez 1987). Sin embargo, un estudio más profundo sobre los usos de dichas formas en otros géneros discursivos (Mailhes 2010) nos lleva a replantearnos los significados básicos. En este sentido, la hipótesis que nos interesa confirmar es que las formas se encuentran vinculadas a la evaluación de los hechos por medio de la posibilidad de ejercer control sobre los mismos . Si existe control, se puede seleccionar la perífrasis; si no existe, la forma sintética será más apropiada. La ausencia de control puede dar lugar a una posibilidad más o menos remota así como a la profecía, dos esferas donde la variación es explotada

Back to the future to revisit meanings

Tanto en los estudios sincrónicos como en los diacrónicos queda en evidencia que el español posee diferentes formas de expresar el tiempo futuro. Por ejemplo, la desinencia del futuro morfológico (-ré) alterna en el español actual con la perífrasis verbal ir+a+infinitivo tal y como se ve en los siguientes ejemplos de la variedad rioplatense: (1) CFK advirtió que "Vamos a sostener este modelo de crecimiento con todas las decisiones que haya que tomar" (Diario Digital 25-04-2012); (2) Rossi aseguró que votarán a favor de YPF unos doscientos diputados (La Nación 28-04-2012). Este hecho ha sido analizado por innumerables estudios y autores, muchos de los cuales se han aproximado a este tema desde la perspectiva variacionista que relaciona significados y contextos (Martínez 1987, Sedano 1994, Company 1999, Alaniz 2010); esta perspectiva explica dicha alternancia por medio de un continuum de factualidad el cual va desde la mayor factualidad de la perífrasis a la menor factualidad de la forma sintética. El análisis de los datos de acuerdo con dichos significados básicos postulados parecía confirmar la hipótesis, al menos en los contextos relacionados con la comunicación oral cotidiana (Martínez 1987). Sin embargo, un estudio más profundo sobre los usos de dichas formas en otros géneros discursivos (Mailhes 2010) nos lleva a replantearnos los significados básicos. En este sentido, la hipótesis que nos interesa confirmar es que las formas se encuentran vinculadas a la evaluación de los hechos por medio de la posibilidad de ejercer control sobre los mismos . Si existe control, se puede seleccionar la perífrasis; si no existe, la forma sintética será más apropiada. La ausencia de control puede dar lugar a una posibilidad más o menos remota así como a la profecía, dos esferas donde la variación es explotada