Internal rotor friction instability

The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations

Minimax estimation of the Wigner function in quantum homodyne tomography with ideal detectors

We estimate the quantum state of a light beam from results of quantum homodyne measurements performed on identically prepared pulses. The state is represented through the Wigner function, a ``quasi-probability density'' on $\mathbb{R}^{2}$ which may take negative values and must respect intrinsic positivity constraints imposed by quantum physics. The data consists of $n$ i.i.d. observations from a probability density equal to the Radon transform of the Wigner function. We construct an estimator for the Wigner function, and prove that it is minimax efficient for the pointwise risk over a class of infinitely differentiable functions. A similar result was previously derived by Cavalier in the context of positron emission tomography. Our work extends this result to the space of smooth Wigner functions, which is the relevant parameter space for quantum homodyne tomography.Comment: 15 page

Dual training in Europe: A policy fad or a policy turn?

History and International Relation

A double-layer Boussinesq-type model for highly nonlinear and dispersive waves

28 pages, 5 figures. Soumis à Proceedings of the Royal Society of London A.We derive and analyze in the framework of the mild-slope approximation a new double-layer Boussinesq-type model which is linearly and nonlinearly accurate up to deep water. Assuming the flow to be irrotational, we formulate the problem in terms of the velocity potential thereby lowering the number of unknowns. The model derivation combines two approaches, namely the method proposed by Agnon et al. (Agnon et al. 1999, J. Fluid Mech., 399 pp. 319-333) and enhanced by Madsen et al. (Madsen et al. 2003, Proc. R. Soc. Lond. A, 459 pp. 1075-1104) which consists in constructing infinite-series Taylor solutions to the Laplace equation, to truncate them at a finite order and to use Padé approximants, and the double-layer approach of Lynett & Liu (Lynett & Liu 2004, Proc. R. Soc. Lond. A, 460 pp. 2637-2669) allowing to lower the order of derivatives. We formulate the model in terms of a static Dirichlet-Neumann operator translated from the free surface to the still-water level, and we derive an approximate inverse of this operator that can be built once and for all. The final model consists of only four equations both in one and two horizontal dimensions, and includes only second-order derivatives, which is a major improvement in comparison with so-called high-order Boussinesq models. A linear analysis of the model is performed and its properties are optimized using a free parameter determining the position of the interface between the two layers. Excellent dispersion and shoaling properties are obtained, allowing the model to be applied up to deep water. Finally, numerical simulations are performed to quantify the nonlinear behaviour of the model, and the results exhibit a nonlinear range of validity reaching deep water areas

First detection in Europe of the metallo-β-lactamase IMP-15 in clinical strains of Pseudomonas putida and Pseudomonas aeruginosa

AbstractIn a prospective study (2009–2011) in healthcare institutions from the Canary Islands (Spain), 6 out of 298 carbapenem non-susceptible Pseudomonas aeruginosa isolates produced a metallo-β-lactamase: four IMP-15, two VIM-2 (including one IMP-15-positive isolate) and one VIM-1. Multilocus sequence typing identified the single VIM-1-producing isolate as clone ST111 and two IMP-15-producing isolates as ST606, but, strikingly, bacterial re-identification revealed that the other three isolates (producing IMP-15 and/or VIM-2) were actually Pseudomonas putida. Further retrospective analysis revealed a very high prevalence (close to 50%) of carbapenem resistance in this environmental species. Hence, we report the simultaneous emergence in hospitals on the Canary Islands of P. putida and P. aeruginosa strains producing IMP-15, a metallo-β-lactamase not previously detected in Europe, and suggest an underestimated role of P. putida as a nosocomial reservoir of worrying transferable resistance determinants

Blended Learning como complemento a la formación presencial en el proceso de enseñanza en la Educación Superior

The scientific-technical revolution has impacted the Pedagogy of Higher Education, specifically in the way that students can assimilate knowledge and in turn has generated a problem, which is how to use these technologies by teachers. That is why the present work presents an experience where a group of methodological procedures are presented to use the virtual classroom as a means of teaching, extensible to the different types of classes that teaching in universities requires. It is based on knowledge management through the use of new learning scenarios and the methodology of the forms of organization of the teaching-learning process of higher education. An analysis is offered on the experiences of the different careers that have built the virtual classrooms of their subject as a result of the different versions of the course.La revolución científico-técnica ha impactado la Pedagogía de la Educación Superior, específicamente en la forma en que los alumnos pueden asimilar el conocimiento y a su vez ha generado un problema, el cual consiste en cómo utilizar esas tecnologías por parte del profesorado. Es por ello que el presente trabajo presenta una experiencia donde se presentan un grupo de procederes metodológicos para utilizar el aula virtual como medio de enseñanza, extensible a los diferentes tipos de clases que exige la didáctica en las universidades. Se fundamenta en la gestión del conocimiento mediante el uso de los nuevos escenarios de aprendizajes y la metodología de las formas de organización del proceso de enseñanza aprendizaje de la Educación superior.  Se ofrece un análisis sobre las experiencias de las diferentes carreras que han montado las aulas virtuales de su asignatura como resultado de las diferentes versiones del curso

Case Report Eradication of Burkholderia cepacia Using Inhaled Aztreonam Lysine in Two Patients with Bronchiectasis

There are not many articles about the chronic bronchial infection/colonization in patients with underlying lung disease other than cystic fibrosis (CF), especially with non-CF bronchiectasis (NCFBQ). The prevalence of B. cepacia complex is not well known in NCFBQ. The vast majority of published clinical data on Burkholderia infection in individuals with CF is comprised of uncontrolled, anecdotal, and/or single center experiences, and no consensus has emerged regarding treatment. We present two cases diagnosed with bronchiectasis (BQ) of different etiology, with early pulmonary infection by B. cepacia complex, which was eradicated with inhaled aztreonam lysine

Optimal estimation of qubit states with continuous time measurements

We propose an adaptive, two steps strategy, for the estimation of mixed qubit states. We show that the strategy is optimal in a local minimax sense for the trace norm distance as well as other locally quadratic figures of merit. Local minimax optimality means that given $n$ identical qubits, there exists no estimator which can perform better than the proposed estimator on a neighborhood of size $n^{-1/2}$ of an arbitrary state. In particular, it is asymptotically Bayesian optimal for a large class of prior distributions. We present a physical implementation of the optimal estimation strategy based on continuous time measurements in a field that couples with the qubits. The crucial ingredient of the result is the concept of local asymptotic normality (or LAN) for qubits. This means that, for large $n$, the statistical model described by $n$ identically prepared qubits is locally equivalent to a model with only a classical Gaussian distribution and a Gaussian state of a quantum harmonic oscillator. The term `local' refers to a shrinking neighborhood around a fixed state $\rho_{0}$. An essential result is that the neighborhood radius can be chosen arbitrarily close to $n^{-1/4}$. This allows us to use a two steps procedure by which we first localize the state within a smaller neighborhood of radius $n^{-1/2+\epsilon}$, and then use LAN to perform optimal estimation.Comment: 32 pages, 3 figures, to appear in Commun. Math. Phy

Supporting Children with Disabilities in Low- and Middle- Income Countries: Promoting Inclusive Practice within Community-Based Childcare Centres in Malawi through a Bioecological Systems Perspective

RLOsGiven the narrow scope and conceptualisation of inclusion for young children with disabilities in research within low- and middle income countries (LMICs) contexts, we draw on a bioecological systems perspective to propose the parameters for a broader unit of analysis. This perspective situates human development within a specific cultural context in which family, peers and schooling are regarded as key in responding to young children with disabilities in a given setting. We outline a new bioecological model to illustrate the proximal and distal factors that can influence inclusive early development for children with disabilities within LMICs. To illustrate the relevance of this model to early child development research, we consider its application, as a conceptual framework, with reference to a research study in Malawi. The study was designed to promote greater inclusive practice for young children with disabilities in Community-Based Childcare Centres (CBCCs) with a particular focus on the role of the CBCC volunteer ‘caregiver’ in rural Malawi. It has significance for educators, service providers and researchers concerned with facilitating inclusive early development across national boundaries and contexts.ESRC-DFI

Contextual factors and prejudice at the beginning of the migrant influx: The Moroccan case in Seville, Spain

Studies addressing contextual factors associated with anti‐immigrant prejudice have focused on out‐group size and rapid demographic changes in receiving locations. However, the territorial concentration and distribution of ethnic minorities at a local and intraurban level has received little attention. We analyse the relationship between emerging territorial concentration points—alongside other contextual variables—by Moroccans and receiving society's growing prejudice towards them in a city experiencing the start of a migrant influx. We combine survey and census data from five Seville districts (southern Spain). Our results show how rapid changes in the general population's ethnic composition, coupled with Moroccan and economic migrants' territorial concentration, correlate strongly with negative attitudes towards Moroccans at this early stage. However, a weaker relationship between the immigrant percentage and degree of prejudice by the receiving group is observed. We also discuss guidelines for ensuring good, local diversity management to prevent socioterritorial fragmentation in multicultural cities.Ministerio de Economía, Industria y Competitividad de España CSO2014‐55780‐C3‐1‐PMinisterio de Economía, Industria y Competitividad de España SEJ2006-14470Junta de Andalucí