Development of numerical procedures for turbomachinery optimizaion

This Doctoral Thesis deals with high speed turbomachinery optimization and all those tools employed in the optimization process, mainly the optimization algorithm, the parameterization framework and the automatic CFD-based optimization loop. Optimization itself is not just a mean to improve the performance of a generic system, but can be a powerful instigator that helps gaining insight on the physic phenomena behind the observed improvements. As for the optimization engine, a novel surrogate-assisted (SA) genetic algorithm for multi-objective optimization problems, namely GeDEA-II-K, was developed. GeDEA-II-K is grounded on the cooperation between a genetic algorithm, namely GeDEA-II, and the Kriging methodology, with the aim at speeding up the optimization process by taking advantage of the surrogate model. The comparison over two- and three-objective test functions revealed the effectiveness of GeDEA-II-K approach. In order to carry out high speed turbomachinery optimizations, an automatic CFD-based optimization loop built around GeDEA-II-K was constructed. The loop was realized for a UNIX/Linux cluster environment in order to exploit the computational resources of parallel computing. Among the tools, a dedicated parameterization framework for 2D airfoils and 3D blades has been designed based on the displacement filed approach. The effectiveness of both the CFD-based automatic loop and the parameterization was verified on two real-life multi-objective optimization problems: the 2D shape optimization of a supersonic compressor cascade and the 3D shape optimization of the NASA Rotor 67. To better understand the outcomes of the optimization process, a wide section has been dedicated to supersonic flows and their behavior when forced to work throughout compressor cascades. The results obtained surely have demonstrated the effectiveness of the optimization approach, and even more have given deep insight on the physic of supersonic flows in the high speed turbomachinery applications that were studied

Birds of a Feather Flock Together: The Inclusive Effect of Similarity Patterns in Equity Crowdfunding

Crowdfunding is helping to drive financial inclusion by expanding the availability of funds to traditionally excluded and underserved groups of individuals, such as ethnic minority and female entrepreneurs. This study verifies how ethnic and gender similarity between investor and entrepreneur can affect the invested amount in an equity crowdfunding campaign. Using an integrated approach with linear regression and Shapley decomposition, we analyze 8600 investments made by 5996 unique personal shareholder investors in 81 equity crowdfunding campaigns. Results show that similarity patterns seem to significantly influence the amount invested in a campaign but their effects change according to investor’s gender and ethnic origin. In fact, even if female investors give a higher amount to men-led companies, their preference changes if the company is run by a female founder belonging to the same ethnic minority group. Results emphasize equity crowdfunding’s potential as a tool for the financial inclusion of ethnic minority groups of investors and entrepreneurs

The digitalization of sustainability reporting processes: A conceptual framework

Building on the contingency theory, the paper aims to shed light on the contribution provided by technological innovation on sustainability reporting quality. A fuzzy expert system (FES) was developed to evaluate the cumulative effects related to the adoption of digital devices in sustainability reporting practices. The analysis underlined the enabling role covered by Sustainable Enterprise Resources Planning (S-ERP) systems on sustainability reporting processes. In detail, we found that the disclosure of environmental information using technological platforms can lead analysts to a more accurate evaluation

Functionalized multiwalled carbon nanotubes as ultrasound contrast agents

Ultrasonography is a fundamental diagnostic imaging tool in everyday clinical practice. Here, we are unique in describing the use of functionalized multiwalled carbon nanotubes (MWCNTs) as hyperechogenic material, suggesting their potential application as ultrasound contrast agents. Initially, we carried out a thorough investigation to assess the echogenic property of the nanotubes in vitro. We demonstrated their long-lasting ultrasound contrast properties. We also showed that ultrasound signal of functionalized MWCNTs is higher than graphene oxide, pristine MWCNTs, and functionalized single-walled CNTs. Qualitatively, the ultrasound signal of CNTs was equal to that of sulfur hexafluoride (SonoVue), a commercially available contrast agent. Then, we found that MWCNTs were highly echogenic in liver and heart through ex vivo experiments using pig as an animal model. In contrast to the majority of ultrasound contrast agents, we observed in a phantom bladder that the tubes can be visualized within a wide variety of frequencies (i.e., 5.5–10 MHz) and 12.5 MHz using tissue harmonic imaging modality. Finally, we demonstrated in vivo in the pig bladder that MWCNTs can be observed at low frequencies, which are appropriate for abdominal organs. Importantly, we did not report any toxicity of CNTs after 7 d from the injection by animal autopsy, organ histology and immunostaining, blood count, and chemical profile. Our results reveal the enormous potential of CNTs as ultrasound contrast agents, giving support for their future applications as theranostic nanoparticles, combining diagnostic and therapeutic modalities

Group B Streptococcal Colonization in 160 Mother-Baby Pairs: A Prospective Cohort Study

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Adaptation of Pseudomonas aeruginosa to constant sub-inhibitory concentrations of quaternary ammonium compounds

Quaternary ammonium compounds (QACs) are widely used in consumer products for disinfection purposes. QACs are frequently detected in aquatic systems at sub-inhibitory concentrations and were found to affect the development of antimicrobial resistance if bacteria are exposed to increasing concentrations. However, the effect of a constant sub-inhibitory concentration on the development of bacterial resistance is unknown. A constant exposure to 88% of the minimum inhibitory concentration (MIC) of benzalkonium chloride (BAC) led to an increase of the MIC of P. aeruginosa. It increased from 80 mg l(-1) to 150 mg l(-1) after 10 cycles of exposure and remained stable after removal of BAC. When exposed to cetyltrimethyl ammonium chloride (CTMA), P. aeruginosa's MIC increased from 110 mg l(-1) to 160 mg l(-1) after 10 cycles of exposure and decreased to 120 mg l(-1) after removal of CTMA. Additionally, cross-resistance between the QACs was observed. When exposed to BAC, the MIC for CTMA increased from 110 mg l(-1) to 200 mg l(-1), and when exposed to CTMA, the MIC for BAC increased from 80 mg l(-1) to 160 mg l(-1). In contrast, the susceptibility to 16 antibiotics was not significantly affected by exposure to QACs. Finally, analyses of the membranes' nanomechanical properties of P. aeruginosa with atomic force microscopy (AFM) showed increases in cell roughness, adhesion and stiffness after treatment with CTMA. Since sub-inhibitory concentrations of QACs can be detected in (technical) aquatic systems including sediments, this may lead to a dissemination of bacteria with higher QAC resistance in the environmen

Serum fatty acids and risk of cutaneous melanoma: a population-based case-control study

Background. Some observational studies have suggested that excess dietary intake of polyunsaturated fatty acids such as linoleic acid increases cutaneous melanoma risk. We aimed at examining the association between serum fatty acids and melanoma risk by conducting a population-based case-control study in a northern Italy community. Methods. \ue062e percentage composition of 12 fatty acids was determined in 51 newly diagnosed melanoma patients and 51 age- and sex-matched population controls by extracting total lipids from serum samples using thin layer and gas chromatography. Conditional logistic regression was used to estimate the relative risk of melanoma associated with tertiles of percentage composition of each fatty acid as well as groupings including saturated, monounsaturated, and polyunsaturated fatty acids. Results. We found a slightly increased melanoma risk for stearic and arachidic acids proportion, with and without adjustment for potential confounders. For an n-3 polyunsaturated fatty acid, docosapentaenoic acid, we found a male-specic direct association with melanoma risk. o other associations emerged for the other saturated, monounsaturated, and polyunsaturated fatty acids, individually or grouped by type. Conclusions. These fndings do not suggest a major role of fatty acids, including linoleic acid, on risk of cutaneous melanoma, though their evaluation is limited by the small sample size

Design evaluation and performance assessment of rotorcraft technology by 2050

The extended Clean Sky Joint Technology Initiative (JTI) within the EU Horizon 2020 Framework Programme [Ref. 1] proposes to introduce a number of concept aircraft and rotorcraft to replace reference technology counterparts at different time scales (2020/2035/2050). This Clean Sky 2 (CS2) promotes the importance of those concept configurations and their application in the future. An increasing global demand within and outside the European Union (EU) for an efficient air mobility and transportation system (i.e. more flexible, resilient, effective and affordable), and future projected growth for its application, will lead to the requirement for development of highly optimised transportation solutions

The upgrade of the ASACUSA scintillating bar detector for antiproton annihilation measurements

Antiproton annihilations on matter nuclei are usually detected by tracking the charged pions emitted in the process. A detector made of plastic scintillating bars have been built and used in the ASACUSA experiment for the last 10 years. Ageing, movements and transports caused stress on the internal mechanical structure and impacted mostly on the optical readout system which was eventually upgraded: the so far used multi-anode photo-multiplier tubes (PMTs) have been replaced by silicon photomultipliers (SiPM) and the front-end electronics had to be adapted to cope with the new signal formation. This work describes the design and operations of the upgrade, as well as the validation tests with cosmic rays

Nanomotion Spectroscopy as a New Approach to Characterize Bacterial Virulence

Atomic force microscopy (AFM)-based nanomotion detection is a label-free technique that has been used to monitor the response of microorganisms to antibiotics in a time frame of minutes. The method consists of attaching living organisms onto an AFM cantilever and in monitoring its nanometric scale oscillations as a function of different physical-chemical stimuli. Up to now, we only used the cantilever oscillations variance signal to assess the viability of the attached organisms. In this contribution, we demonstrate that a more precise analysis of the motion pattern of the cantilever can unveil relevant medical information about bacterial phenotype. We used B. pertussis as the model organism, it is a slowly growing Gram-negative bacteria which is the agent of whooping cough. It was previously demonstrated that B. pertussis can expresses different phenotypes as a function of the physical-chemical properties of the environment. In this contribution, we highlight that B. pertussis generates a cantilever movement pattern that depends on its phenotype. More precisely, we noticed that nanometric scale oscillations of B. pertussis can be correlated with the virulence state of the bacteria. The results indicate a correlation between metabolic/virulent bacterial states and bacterial nanomotion pattern and paves the way to novel rapid and label-free pathogenic microorganism detection assays.Centro de Investigación y Desarrollo en Fermentaciones IndustrialesInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada