Noise Measurements of a Low-Noise Top-Mounted Propulsion Installation for a Supersonic Airliner

A model-scale exhaust system was tested to validate low-noise concepts and noise prediction methods. The tests involved far-field acoustics, translating phased array, and particle image velocimetry; this report covers the far-field acoustic measurements. Data were acquired for a series of nozzles with different chevron designs, both uninstalled and installed on a representative aircraft planform. The impact of the various chevron treatments on the far-field noise was documented, along with the impact of the pylon and planform. For the baseline nozzle, installation produced a 2EPNdB reduction, as assumed in system studies. Chevrons were used to shift noise sources upstream to maximize the installation benefits and to reduce unshielded sources downstream. These resulted in reductions of 4-5EPNdB relative to the uninstalled baseline nozzle. Detailed analysis of spectral directivities behind the integrated EPNL metric gave insight into how well these concepts actually work. When correlated with particle image velocimetry measurements and phased array measurements, reported in companion papers, the explanation of acoustic benefits from top-mounted propulsion is clear as is the path toward optimization of the concept

The control of near-wall turbulence through surface texturing

Certain surfaces that exhibit small textured features can interact with near-wall turbulence and reduce drag, which is of great interest to industries in the aerospace, naval, transport and energy sectors. This paper reviews and discusses the dynamic mechanisms at play in that interaction. General principles of application across different technologies are discussed, and the parameters of interest and relevance are identified. It is argued that the main effect of these surfaces can be expressed as an offset between the positions of the virtual, equivalent smooth walls perceived by different parts of the flow, namely by the mean velocity profile and by the background turbulence, which remains otherwise smooth-like. Individual technologies are also reviewed, including superhydrophobic surfaces, riblets and permeable substrates, with particular emphasis on physical mechanisms that are specific to each technology. We discuss the capillary waves that form in superhydrophobic surfaces and the spanwise-elongated rollers that form over riblets and permeable surfaces

The Cambrian of the Iberian Peninsula : an overview

This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups

Validity of the N\'{e}el-Arrhenius model for highly anisotropic Co_xFe_{3-x}O_4 nanoparticles

We report a systematic study on the structural and magnetic properties of Co_{x}Fe_{3-x}O_{4} magnetic nanoparticles with sizes between $5$ to $25$ nm, prepared by thermal decomposition of Fe(acac)_{3} and Co(acac)_{2}. The large magneto-crystalline anisotropy of the synthesized particles resulted in high blocking temperatures ($42$ K \leqq $T_B$ $\leqq 345$ K for $5 \leqq$ d $\leqq 13$ nm ) and large coercive fields ($H_C \approxeq 1600$ kA/m for $T = 5$ K). The smallest particles ($=5$ nm) revealed the existence of a magnetically hard, spin-disordered surface. The thermal dependence of static and dynamic magnetic properties of the whole series of samples could be explained within the N\'{e}el-Arrhenius relaxation framework without the need of ad-hoc corrections, by including the thermal dependence of the magnetocrystalline anisotropy constant $K_1(T)$ through the empirical Br\"{u}khatov-Kirensky relation. This approach provided $K_1(0)$ values very similar to the bulk material from either static or dynamic magnetic measurements, as well as realistic values for the response times ($\tau_0 \simeq 10^{-10}$ s). Deviations from the bulk anisotropy values found for the smallest particles could be qualitatively explained based on Zener\'{}s relation between $K_1(T)$ and M(T)

Brote de eritema infeccioso en un centro de salud urbano

ObjetivosAnalizar las características clínicas y serológicas de un brote de eritema infeccioso en pacientes que acudieron a las 2 consultas de pediatría del Centro de Salud de Soria Norte.DiseñoEstudio descriptivo, transversal.EmplazamientoConsultas de pediatría del Centro de Salud de Soria Norte.PacientesUna vez sospechado el brote, se estudiaron niños con clínica sugestiva de eritema infeccioso que acudieron sucesivamente a las 2 consultas de pediatría de Soria Norte durante los meses de abril a agosto de 1998 y consintieron en la práctica de analítica.IntervencionesSe realizó registro de síntomas clínicos, serología, hemograma y evolución de 25 pacientes.ResultadosSe estudiaron 25 pacientes del total de casos, confirmando nuestra sospecha diagnóstica en un 84% de los casos. No se observaron diferencias en ambos sexos, con una edad media de 6,1 años, y DE, 2,015. El signo clínico más constante fue el exantema en mejillas, presente en un 100% de los casos confirmados, seguido de exantema en tronco y extremidades en un 57,1%, adenopatías en un 9,5% y fiebre en un 4,7%. En ningún caso se objetivaron complicaciones.ConclusionesLos resultados de este trabajo permiten confirmar la existencia de un brote de eritema infeccioso en nuestro medio. Consideramos útil la confirmación serológica para constatar la presencia de un brote y poder realizar un enfoque terapéutico (frente a complicaciones posibles) y preventivo adecuado. Destacamos el carácter, en general, benigno de la enfermedad.ObjectivesTo analyse the clinical and serological characteristics of an outbreak of infectious erythema in patients attending the two paediatrics clinics at the Soria Norte Health Centre.DesignCross-sectional, descriptive study.SettingPaediatrics clinics of the Soria Norte Health Centre.PatientsOnce the outbreak was suspected, the study was conducted on children with a clinical picture suggesting infectious erythema who attended successively two Soria Norte paediatrics clinics between April and August 1998 and who consented to the analyses.InterventionsThe clinical symptoms, serology, haemogram and evolution of 25 patients were recorded.Results25 patients of the total were studied and diagnostic suspicion was confirmed in 84% of the cases. There were no differences between sexes, with an average age of 6.1, SD 2.015. The most constant clinical sign was exanthem on the cheeks, present in 100% of the cases confirmed, followed by 57% exanthem on the trunk and limbs, 9.5% adenopathies and 4.7% temperature. No complications were found in any case.ConclusionsThe results of this study confirm the existence of an outbreak of infectious erythema in our area. Serological confirmation of an outbreak is useful and can lay the basis for a proper therapeutic and preventive focus (against possible complications). We highlight the generally benign nature of the disease

Black holes and Hawking radiation in spacetime and its analogues

These notes introduce the fundamentals of black hole geometry, the thermality of the vacuum, and the Hawking effect, in spacetime and its analogues. Stimulated emission of Hawking radiation, the trans-Planckian question, short wavelength dispersion, and white hole radiation in the setting of analogue models are also discussed. No prior knowledge of differential geometry, general relativity, or quantum field theory in curved spacetime is assumed.Comment: 31 pages, 9 figures; to appear in the proceedings of the IX SIGRAV School on 'Analogue Gravity', Como (Italy), May 2011, eds. D. Faccio et. al. (Springer

IgE-Mediated Hypersensitivity Reactions to Cannabis in Laboratory Personnel

Background: There have been sporadic reports of hypersensitivity reactions to plants of the Cannabinaceae family (hemp and hops), but it has remained unclear whether these reactions are immunologic or nonimmunologic in nature. Objective: We examined the IgE-binding and histamine-releasing properties of hashish and marijuana extracts by CAP-FEIA and a basophil histamine release test. Methods: Two workers at a forensic laboratory suffered from nasal congestion, rbinitis, sneezing and asthmatic symptoms upon occupational contact with hashish or marijuana, which they had handled frequently for 25 and 16 years, respectively. Neither patient had a history of atopic disease. Serum was analyzed for specific IgE antibodies to hashish or marijuana extract by research prototype ImmunoCAP, and histamine release from basophils upon exposure to hashish or marijuana extracts was assessed. Results were matched to those of 4 nonatopic and 10 atopic control subjects with no known history of recreational or occupational exposure to marijuana or hashish. Results: Patient 1 had specific IgE to both hashish and marijuana (CAP class 2), and patient 2 to marijuana only (CAP class 2). Controls proved negative for specific IgE except for 2 atopic individuals with CAP class 1 to marijuana and 1 other atopic individual with CAP class 1 to hashish. Stimulation of basophils with hashish or marijuana extracts elicited histamine release from basophils of both patients and 4 atopic control subjects. Conclusions: Our results suggest an IgE-related pathomechanism for hypersensitivity reactions to marijuana or hashish. Copyright (C) 2011 S. Karger AG, Base

Exploring the Consistency of Data Collected in Archaeological Geophysics: A Case Study from the Iron Age Hillfort of Villasviejas del Tamuja (Extremadura, Spain)

Different geophysical methods applied at the settlement of Villasviejas del Tamuja (Botija, Spain) have identified robust anomalies located at the same position, but some anomalies are reflected by only one method. Furthermore, analysing the spatial correlation of these anomalies is of fundamental importance for obtaining a correct archaeological interpretation. In this work, we analysed the main results of electrical resistivity tomography (ERT), ground-penetrating radar (GPR) and magnetic gradiometry methods in a particular area of the archaeological site. In this analysis, we performed graphical and numerical spatial correlation analyses of the anomalies and observed strong agreement among the results provided by each method. Certain anomalies were reflected only in the magnetic and ERT studies. The results highlight the importance of applying several geophysical methods and performing spatial correlational analyses. Furthermore, the methodology that we have applied to evaluate the spatial correlation offers interesting results

Tuneable photoconductivity and mobility enhancement in printed MoS 2 /graphene composites

This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.With the aim of increasing carrier mobility in nanosheet-network devices, we have investigated MoS2–graphene composites as active regions in printed photodetectors. Combining liquid exfoliation and inkjet-printing, we fabricated all-printed photodetectors with graphene electrodes and MoS2–graphene composite channels with various graphene mass fractions (0  ≤  M f  ≤  16 wt%). The increase in channel dark conductivity with M f was consistent with percolation theory for composites below the percolation threshold. While the photoconductivity increased with graphene content, it did so more slowly than the dark conductivity, such that the fractional photoconductivity decayed rapidly with increasing M f. We propose that both mobility and dark carrier density increase with graphene content according to percolation-like scaling laws, while photo-induced carrier density is essentially independent of graphene loading. This leads to percolation-like scaling laws for both photoconductivity and fractional photoconductivity—in excellent agreement with the data. These results imply that channel mobility and carrier density increase up to 100-fold with the addition of 16 wt% graphene.We acknowledge the Science Foundation Ireland (SFI/12/RC/2278), the European Commission (n° 696656, Graphene Flagship) and the European Research Council (FUTURE-PRINT)