Parametric-adjoint approach for the efficient optimization of flow-exposed geometries

Today, the optimization of ship hulls and appendages, including energy-saving devices, is typically undertaken by means of coupling parametric modelling (variable geometry) and Computational Fluid Dynamics (CFD). A relatively new approach is based on parameter-free solutions, solving the adjoint RANS equations for selected objective functions (like drag and lift). Combining parametric and parameter-free solutions is an emerging technique that helps to effectively optimize shapes without leaving the CAD domain of the model, making it easier to integrate in the overall design process. On the basis of the Computer Aided Engineering (CAE) software CAESES, a parametric- adjoint approach will be presented. The approach is built on concatenating so-called “design velocities” and “adjoint shape sensitivities”. Design velocities yield regions of influence from a pure geometric point of view within a given parametric model. Meanwhile, adjoint shape sensitivities show where and how changes of the surface affect the objective. Overlaying the surface distributions of both the design velocities and the adjoint shape sensitivities result in so-called “parametric sensitivities.” These help to understand the importance of all parameters wi hin the chosen model. This approach will be demonstrated on a practical hull form optimization example

Seasonality in extra-pulmonary tuberculosis notifications in Germany 2004-2014- a time series analysis

Background Seasonality in tuberculosis (TB) has been found in different parts of the world, showing a peak in spring/summer and a trough in autumn/winter. The evidence is less clear which factors drive seasonality. It was our aim to identify and evaluate seasonality in the notifications of TB in Germany, additionally investigating the possible variance of seasonality by disease site, sex and age group. Methods We conducted an integer-valued time series analysis using national surveillance data. We analysed the reported monthly numbers of started treatments between 2004 and 2014 for all notified TB cases and stratified by disease site, sex and age group. Results We detected seasonality in the extra-pulmonary TB cases (N = 11,219), with peaks in late spring/summer and troughs in fall/winter. For all TB notifications together (N = 51,090) and for pulmonary TB only (N = 39,714) we did not find a distinct seasonality. Additional stratified analyses did not reveal any clear differences between age groups, the sexes, or between active and passive case finding. Conclusion We found seasonality in extra-pulmonary TB only, indicating that seasonality of disease onset might be specific to the disease site. This could point towards differences in disease progression between the different clinical disease manifestations. Sex appears not to be an important driver of seasonality, whereas the role of age remains unclear as this could not be sufficiently investigated.Peer Reviewe

Corrigendum: Calibrating spectrometers for measurements of the spectral irradiance caused by solar radiation (2020 Metrologia 57 065027)

We correct an error in equation (60) of the original publication

Calibrating spectrometers for measurements of the spectral irradiance caused by solar radiation

Measuring the spectral irradiance of solar radiation is required in many fields of science and technology. In this work, we present an in-depth discussion of the measuring procedure and required corrections for such measurements. We also describe our measurement uncertainty analysis, which is based on a Monte-Carlo procedure in accordance with the Guide to the expression of uncertainty in measurement (JCGM, Paris, 2008). For this purpose, fifteen uncertainty sources are identified, analyzed and described analytically. As a specific application example, we describe the instrumentation and procedure for determining the spectral irradiance of a solar simulator at the ISO/IEC 17 025 accredited solar cell calibration laboratory ISFH CalTeC and the corresponding measurement uncertainty analysis. Moreover, we provide a Python implementation for this calculation along with the paper. We show that for state-of-the-art instrumentation, significant uncertainty contributions arise from the reference lamp (primary calibration standard), stray light and signal-to-noise ratio. If sharp spectral features are present (which is common, e.g. for Xenon lamps), spectral bandwidth and wavelength uncertainty also contribute significantly to the overall uncertainty. © 2020 BIPM & IOP Publishing Lt

ON OPTICAL QUANTIFICATION OF CAVITATION PROPERTIES

SUMMARY This paper investigates quantitative cavitation characterization. In this context we propose shadow imaging to determine cavitation thickness and tip vortex volume. We propose a laser adjustment for absolute calibration and address cavitation extent by means of image processing. We present advantages and disadvantages of automatic processing with regard to our proposed techniques. Our main focus is on the novel cavitation thickness and tip vortex occurrence processing. Due to turbulent fluctuations all used techniques provide statistical results. The accuracy of single measurements mainly depends on camera resolution, aberrations in the optical path, illumination and optical access. INTRODUCTION In the framework of a joint research project between Hamburg Ship Model Basin (HSVA), Potsdam Model Basin (SVA), Technical University of Hamburg Harburg (TU-HH) and University of Rostock (URO), supported by the Federal Ministry of Economics and Technology (BMWI), quantitative measurements for determination of water quality and its influence on cavitation processes are performed. The goal of the project is a reliable prognosis of cavitation on ship propellers based on experiments in cavitation tunnels. We propose image processing techniques to quantify cavitation properties like cavitation thickness, cavitation extent and tip vortex volume. Conventionally, experts at the model basins use their experience to accurately describe cavitation by means of drawings. In addition, photos and high speed videos are provided to customers. However, the information derived from this data is mostly limited to the cavitation extent and the area of the tip vortex. To better describe the cavitation thickness, laser based techniques have been described in [1] and i

SARS-CoV-2 Omicron variants BA.1 and BA.2 both show similarly reduced disease severity of COVID-19 compared to Delta, Germany, 2021 to 2022

German national surveillance data analysis shows that hospitalisation odds associated with Omicron lineage BA.1 or BA.2 infections are up to 80% lower than with Delta infection, primarily in ≥ 35-year-olds. Hospitalised vaccinated Omicron cases’ proportions (2.3% for both lineages) seemed lower than those of the unvaccinated (4.4% for both lineages). Independent of vaccination status, the hospitalisation frequency among cases with Delta seemed nearly threefold higher (8.3%) than with Omicron (3.0% for both lineages), suggesting that Omicron inherently causes less severe disease.Peer Reviewe

Experimental Determination of the Uncertainty of the Absorption Coefficient of Crystalline Silicon

Based on a combined analysis of spectroscopic ellipsometry, reflectance and transmittance measurements as well as spectrally resolved luminescence measurements and spectral responsivity measurements, we present data of the coefficient of band-to-band absorption of crystalline silicon at 295 K in the wavelength range 250 - 1450 nm. A systematic measurement uncertainty analysis according to the "Guide to the Expression of Uncertainty in Measurements" (GUM) is carried out for each method, showing that the relative uncertainty of the absorption coefficient data so determined is of the order of 0.3% at 300 nm, 1% at 900 nm, 10% at 1200 nm and 180% at 1450 nm. The data are consolidated by comparison of measurements carried out independently at different institutions. The uncertainty of solar cell energy conversion predictions by means of simulations due to the uncertainty of the absorption coefficient data is shown to be of the order of 0.1% relative.Deutsche Bundesstiftung UmweltState of Lower Saxon